// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Driver for OHCI 1394 controllers
 *
 * Copyright (C) 2003-2006 Kristian Hoegsberg <krh@bitplanet.net>
 */

#include <linux/bitops.h>
#include <linux/bug.h>
#include <linux/compiler.h>
#include <linux/delay.h>
#include <linux/device.h>
#include <linux/dma-mapping.h>
#include <linux/firewire.h>
#include <linux/firewire-constants.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/list.h>
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/mutex.h>
#include <linux/pci.h>
#include <linux/pci_ids.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/string.h>
#include <linux/time.h>
#include <linux/vmalloc.h>
#include <linux/workqueue.h>

#include <asm/byteorder.h>
#include <asm/page.h>

#ifdef CONFIG_PPC_PMAC
#include <asm/pmac_feature.h>
#endif

#include "core.h"
#include "ohci.h"
#include "packet-header-definitions.h"
#include "phy-packet-definitions.h"

#include <trace/events/firewire.h>

static u32 cond_le32_to_cpu(__le32 value, bool has_be_header_quirk);

#define CREATE_TRACE_POINTS
#include <trace/events/firewire_ohci.h>

#define ohci_notice(ohci, f, args...)   dev_notice(ohci->card.device, f, ##args)
#define ohci_err(ohci, f, args...)      dev_err(ohci->card.device, f, ##args)

#define DESCRIPTOR_OUTPUT_MORE          0
#define DESCRIPTOR_OUTPUT_LAST          (1 << 12)
#define DESCRIPTOR_INPUT_MORE           (2 << 12)
#define DESCRIPTOR_INPUT_LAST           (3 << 12)
#define DESCRIPTOR_STATUS               (1 << 11)
#define DESCRIPTOR_KEY_IMMEDIATE        (2 << 8)
#define DESCRIPTOR_PING                 (1 << 7)
#define DESCRIPTOR_YY                   (1 << 6)
#define DESCRIPTOR_NO_IRQ               (0 << 4)
#define DESCRIPTOR_IRQ_ERROR            (1 << 4)
#define DESCRIPTOR_IRQ_ALWAYS           (3 << 4)
#define DESCRIPTOR_BRANCH_ALWAYS        (3 << 2)
#define DESCRIPTOR_WAIT                 (3 << 0)

#define DESCRIPTOR_CMD                  (0xf << 12)

struct descriptor {
        __le16 req_count;
        __le16 control;
        __le32 data_address;
        __le32 branch_address;
        __le16 res_count;
        __le16 transfer_status;
} __aligned(16);

#define CONTROL_SET(regs)       (regs)
#define CONTROL_CLEAR(regs)     ((regs) + 4)
#define COMMAND_PTR(regs)       ((regs) + 12)
#define CONTEXT_MATCH(regs)     ((regs) + 16)

#define AR_BUFFER_SIZE  (32*1024)
#define AR_BUFFERS_MIN  DIV_ROUND_UP(AR_BUFFER_SIZE, PAGE_SIZE)
/* we need at least two pages for proper list management */
#define AR_BUFFERS      MAX(2, AR_BUFFERS_MIN)

#define MAX_ASYNC_PAYLOAD       4096
#define MAX_AR_PACKET_SIZE      (16 + MAX_ASYNC_PAYLOAD + 4)
#define AR_WRAPAROUND_PAGES     DIV_ROUND_UP(MAX_AR_PACKET_SIZE, PAGE_SIZE)

struct ar_context {
        struct fw_ohci *ohci;
        struct page *pages[AR_BUFFERS];
        void *buffer;
        dma_addr_t dma_addrs[AR_BUFFERS];
        struct descriptor *descriptors;
        dma_addr_t descriptors_bus;
        void *pointer;
        unsigned int last_buffer_index;
        u32 regs;
        struct work_struct work;
};

struct context;

typedef int (*descriptor_callback_t)(struct context *ctx,
                                     struct descriptor *d,
                                     struct descriptor *last);

/*
 * A buffer that contains a block of DMA-able coherent memory used for
 * storing a portion of a DMA descriptor program.
 */
struct descriptor_buffer {
        struct list_head list;
        dma_addr_t buffer_bus;
        size_t buffer_size;
        size_t used;
        struct descriptor buffer[];
};

struct context {
        struct fw_ohci *ohci;
        u32 regs;
        int total_allocation;
        u32 current_bus;
        bool running;

        /*
         * List of page-sized buffers for storing DMA descriptors.
         * Head of list contains buffers in use and tail of list contains
         * free buffers.
         */
        struct list_head buffer_list;

        /*
         * Pointer to a buffer inside buffer_list that contains the tail
         * end of the current DMA program.
         */
        struct descriptor_buffer *buffer_tail;

        /*
         * The descriptor containing the branch address of the first
         * descriptor that has not yet been filled by the device.
         */
        struct descriptor *last;

        /*
         * The last descriptor block in the DMA program. It contains the branch
         * address that must be updated upon appending a new descriptor.
         */
        struct descriptor *prev;
        int prev_z;

        descriptor_callback_t callback;
};

struct at_context {
        struct context context;
        struct work_struct work;
        bool flushing;
};

struct iso_context {
        struct fw_iso_context base;
        struct context context;
        unsigned long flushing_completions;
        u8 sync;
        u8 tags;
        union {
                struct {
                        u16 last_timestamp;
                        size_t header_length;
                        void *header;
                } sc;
                struct {
                        u32 buffer_bus;
                        u16 completed;
                } mc;
        };
};

#define CONFIG_ROM_SIZE         (CSR_CONFIG_ROM_END - CSR_CONFIG_ROM)

struct fw_ohci {
        struct fw_card card;

        __iomem char *registers;
        int node_id;
        int generation;
        int request_generation; /* for timestamping incoming requests */
        unsigned quirks;
        unsigned int pri_req_max;
        u32 bus_time;
        bool bus_time_running;
        bool is_root;
        bool csr_state_setclear_abdicate;
        int n_ir;
        int n_it;
        /*
         * Spinlock for accessing fw_ohci data.  Never call out of
         * this driver with this lock held.
         */
        spinlock_t lock;

        struct mutex phy_reg_mutex;

        void *misc_buffer;
        dma_addr_t misc_buffer_bus;

        struct ar_context ar_request_ctx;
        struct ar_context ar_response_ctx;
        struct at_context at_request_ctx;
        struct at_context at_response_ctx;

        u32 it_context_support;
        u32 it_context_mask;     /* unoccupied IT contexts */
        struct iso_context *it_context_list;
        u64 ir_context_channels; /* unoccupied channels */
        u32 ir_context_support;
        u32 ir_context_mask;     /* unoccupied IR contexts */
        struct iso_context *ir_context_list;
        u64 mc_channels; /* channels in use by the multichannel IR context */
        bool mc_allocated;

        __be32    *config_rom;
        dma_addr_t config_rom_bus;
        __be32    *next_config_rom;
        dma_addr_t next_config_rom_bus;
        __be32     next_header;

        __le32    *self_id;
        dma_addr_t self_id_bus;

        u32 self_id_buffer[512];
};

static inline struct fw_ohci *fw_ohci(struct fw_card *card)
{
        return container_of(card, struct fw_ohci, card);
}

#define IT_CONTEXT_CYCLE_MATCH_ENABLE   0x80000000
#define IR_CONTEXT_BUFFER_FILL          0x80000000
#define IR_CONTEXT_ISOCH_HEADER         0x40000000
#define IR_CONTEXT_CYCLE_MATCH_ENABLE   0x20000000
#define IR_CONTEXT_MULTI_CHANNEL_MODE   0x10000000
#define IR_CONTEXT_DUAL_BUFFER_MODE     0x08000000

#define CONTEXT_RUN     0x8000
#define CONTEXT_WAKE    0x1000
#define CONTEXT_DEAD    0x0800
#define CONTEXT_ACTIVE  0x0400

#define OHCI1394_MAX_AT_REQ_RETRIES     0xf
#define OHCI1394_MAX_AT_RESP_RETRIES    0x2
#define OHCI1394_MAX_PHYS_RESP_RETRIES  0x8

#define OHCI1394_REGISTER_SIZE          0x800
#define OHCI1394_PCI_HCI_Control        0x40
#define SELF_ID_BUF_SIZE                0x800
#define OHCI_VERSION_1_1                0x010010

static char ohci_driver_name[] = KBUILD_MODNAME;

#define PCI_VENDOR_ID_PINNACLE_SYSTEMS  0x11bd
#define PCI_DEVICE_ID_AGERE_FW643       0x5901
#define PCI_DEVICE_ID_CREATIVE_SB1394   0x4001
#define PCI_DEVICE_ID_JMICRON_JMB38X_FW 0x2380
#define PCI_DEVICE_ID_TI_TSB12LV22      0x8009
#define PCI_DEVICE_ID_TI_TSB12LV26      0x8020
#define PCI_DEVICE_ID_TI_TSB82AA2       0x8025
#define PCI_DEVICE_ID_VIA_VT630X        0x3044
#define PCI_REV_ID_VIA_VT6306           0x46
#define PCI_DEVICE_ID_VIA_VT6315        0x3403

#define QUIRK_CYCLE_TIMER               0x1
#define QUIRK_RESET_PACKET              0x2
#define QUIRK_BE_HEADERS                0x4
#define QUIRK_NO_1394A                  0x8
#define QUIRK_NO_MSI                    0x10
#define QUIRK_TI_SLLZ059                0x20
#define QUIRK_IR_WAKE                   0x40

// On PCI Express Root Complex in any type of AMD Ryzen machine, VIA VT6306/6307/6308 with Asmedia
// ASM1083/1085 brings an inconvenience that the read accesses to 'Isochronous Cycle Timer' register
// (at offset 0xf0 in PCI I/O space) often causes unexpected system reboot. The mechanism is not
// clear, since the read access to the other registers is enough safe; e.g. 'Node ID' register,
// while it is probable due to detection of any type of PCIe error.
#define QUIRK_REBOOT_BY_CYCLE_TIMER_READ        0x80000000

#if IS_ENABLED(CONFIG_X86)

static bool has_reboot_by_cycle_timer_read_quirk(const struct fw_ohci *ohci)
{
        return !!(ohci->quirks & QUIRK_REBOOT_BY_CYCLE_TIMER_READ);
}

#define PCI_DEVICE_ID_ASMEDIA_ASM108X   0x1080

static bool detect_vt630x_with_asm1083_on_amd_ryzen_machine(const struct pci_dev *pdev)
{
        const struct pci_dev *pcie_to_pci_bridge;

        // Detect any type of AMD Ryzen machine.
        if (!static_cpu_has(X86_FEATURE_ZEN))
                return false;

        // Detect VIA VT6306/6307/6308.
        if (pdev->vendor != PCI_VENDOR_ID_VIA)
                return false;
        if (pdev->device != PCI_DEVICE_ID_VIA_VT630X)
                return false;

        // Detect Asmedia ASM1083/1085.
        pcie_to_pci_bridge = pdev->bus->self;
        if (pcie_to_pci_bridge->vendor != PCI_VENDOR_ID_ASMEDIA)
                return false;
        if (pcie_to_pci_bridge->device != PCI_DEVICE_ID_ASMEDIA_ASM108X)
                return false;

        return true;
}

#else
#define has_reboot_by_cycle_timer_read_quirk(ohci) false
#define detect_vt630x_with_asm1083_on_amd_ryzen_machine(pdev)   false
#endif

/* In case of multiple matches in ohci_quirks[], only the first one is used. */
static const struct {
        unsigned short vendor, device, revision, flags;
} ohci_quirks[] = {
        {PCI_VENDOR_ID_AL, PCI_ANY_ID, PCI_ANY_ID,
                QUIRK_CYCLE_TIMER},

        {PCI_VENDOR_ID_APPLE, PCI_DEVICE_ID_APPLE_UNI_N_FW, PCI_ANY_ID,
                QUIRK_BE_HEADERS},

        {PCI_VENDOR_ID_ATT, PCI_DEVICE_ID_AGERE_FW643, 6,
                QUIRK_NO_MSI},

        {PCI_VENDOR_ID_CREATIVE, PCI_DEVICE_ID_CREATIVE_SB1394, PCI_ANY_ID,
                QUIRK_RESET_PACKET},

        {PCI_VENDOR_ID_JMICRON, PCI_DEVICE_ID_JMICRON_JMB38X_FW, PCI_ANY_ID,
                QUIRK_NO_MSI},

        {PCI_VENDOR_ID_NEC, PCI_ANY_ID, PCI_ANY_ID,
                QUIRK_CYCLE_TIMER},

        {PCI_VENDOR_ID_O2, PCI_ANY_ID, PCI_ANY_ID,
                QUIRK_NO_MSI},

        {PCI_VENDOR_ID_RICOH, PCI_ANY_ID, PCI_ANY_ID,
                QUIRK_CYCLE_TIMER | QUIRK_NO_MSI},

        {PCI_VENDOR_ID_TI, PCI_DEVICE_ID_TI_TSB12LV22, PCI_ANY_ID,
                QUIRK_CYCLE_TIMER | QUIRK_RESET_PACKET | QUIRK_NO_1394A},

        {PCI_VENDOR_ID_TI, PCI_DEVICE_ID_TI_TSB12LV26, PCI_ANY_ID,
                QUIRK_RESET_PACKET | QUIRK_TI_SLLZ059},

        {PCI_VENDOR_ID_TI, PCI_DEVICE_ID_TI_TSB82AA2, PCI_ANY_ID,
                QUIRK_RESET_PACKET | QUIRK_TI_SLLZ059},

        {PCI_VENDOR_ID_TI, PCI_ANY_ID, PCI_ANY_ID,
                QUIRK_RESET_PACKET},

        {PCI_VENDOR_ID_VIA, PCI_DEVICE_ID_VIA_VT630X, PCI_REV_ID_VIA_VT6306,
                QUIRK_CYCLE_TIMER | QUIRK_IR_WAKE},

        {PCI_VENDOR_ID_VIA, PCI_DEVICE_ID_VIA_VT6315, 0,
                QUIRK_CYCLE_TIMER /* FIXME: necessary? */ | QUIRK_NO_MSI},

        {PCI_VENDOR_ID_VIA, PCI_DEVICE_ID_VIA_VT6315, PCI_ANY_ID,
                QUIRK_NO_MSI},

        {PCI_VENDOR_ID_VIA, PCI_ANY_ID, PCI_ANY_ID,
                QUIRK_CYCLE_TIMER | QUIRK_NO_MSI},
};

/* This overrides anything that was found in ohci_quirks[]. */
static int param_quirks;
module_param_named(quirks, param_quirks, int, 0644);
MODULE_PARM_DESC(quirks, "Chip quirks (default = 0"
        ", nonatomic cycle timer = "    __stringify(QUIRK_CYCLE_TIMER)
        ", reset packet generation = "  __stringify(QUIRK_RESET_PACKET)
        ", AR/selfID endianness = "     __stringify(QUIRK_BE_HEADERS)
        ", no 1394a enhancements = "    __stringify(QUIRK_NO_1394A)
        ", disable MSI = "              __stringify(QUIRK_NO_MSI)
        ", TI SLLZ059 erratum = "       __stringify(QUIRK_TI_SLLZ059)
        ", IR wake unreliable = "       __stringify(QUIRK_IR_WAKE)
        ")");

static bool param_remote_dma;
module_param_named(remote_dma, param_remote_dma, bool, 0444);
MODULE_PARM_DESC(remote_dma, "Enable unfiltered remote DMA (default = N)");

static inline void reg_write(const struct fw_ohci *ohci, int offset, u32 data)
{
        writel(data, ohci->registers + offset);
}

static inline u32 reg_read(const struct fw_ohci *ohci, int offset)
{
        return readl(ohci->registers + offset);
}

static inline void flush_writes(const struct fw_ohci *ohci)
{
        /* Do a dummy read to flush writes. */
        reg_read(ohci, OHCI1394_Version);
}

/*
 * Beware!  read_phy_reg(), write_phy_reg(), update_phy_reg(), and
 * read_paged_phy_reg() require the caller to hold ohci->phy_reg_mutex.
 * In other words, only use ohci_read_phy_reg() and ohci_update_phy_reg()
 * directly.  Exceptions are intrinsically serialized contexts like pci_probe.
 */
static int read_phy_reg(struct fw_ohci *ohci, int addr)
{
        u32 val;
        int i;

        reg_write(ohci, OHCI1394_PhyControl, OHCI1394_PhyControl_Read(addr));
        for (i = 0; i < 3 + 100; i++) {
                val = reg_read(ohci, OHCI1394_PhyControl);
                if (!~val)
                        return -ENODEV; /* Card was ejected. */

                if (val & OHCI1394_PhyControl_ReadDone)
                        return OHCI1394_PhyControl_ReadData(val);

                /*
                 * Try a few times without waiting.  Sleeping is necessary
                 * only when the link/PHY interface is busy.
                 */
                if (i >= 3)
                        msleep(1);
        }
        ohci_err(ohci, "failed to read phy reg %d\n", addr);
        dump_stack();

        return -EBUSY;
}

static int write_phy_reg(const struct fw_ohci *ohci, int addr, u32 val)
{
        int i;

        reg_write(ohci, OHCI1394_PhyControl,
                  OHCI1394_PhyControl_Write(addr, val));
        for (i = 0; i < 3 + 100; i++) {
                val = reg_read(ohci, OHCI1394_PhyControl);
                if (!~val)
                        return -ENODEV; /* Card was ejected. */

                if (!(val & OHCI1394_PhyControl_WritePending))
                        return 0;

                if (i >= 3)
                        msleep(1);
        }
        ohci_err(ohci, "failed to write phy reg %d, val %u\n", addr, val);
        dump_stack();

        return -EBUSY;
}

static int update_phy_reg(struct fw_ohci *ohci, int addr,
                          int clear_bits, int set_bits)
{
        int ret = read_phy_reg(ohci, addr);
        if (ret < 0)
                return ret;

        /*
         * The interrupt status bits are cleared by writing a one bit.
         * Avoid clearing them unless explicitly requested in set_bits.
         */
        if (addr == 5)
                clear_bits |= PHY_INT_STATUS_BITS;

        return write_phy_reg(ohci, addr, (ret & ~clear_bits) | set_bits);
}

static int read_paged_phy_reg(struct fw_ohci *ohci, int page, int addr)
{
        int ret;

        ret = update_phy_reg(ohci, 7, PHY_PAGE_SELECT, page << 5);
        if (ret < 0)
                return ret;

        return read_phy_reg(ohci, addr);
}

static int ohci_read_phy_reg(struct fw_card *card, int addr)
{
        struct fw_ohci *ohci = fw_ohci(card);

        guard(mutex)(&ohci->phy_reg_mutex);

        return read_phy_reg(ohci, addr);
}

static int ohci_update_phy_reg(struct fw_card *card, int addr,
                               int clear_bits, int set_bits)
{
        struct fw_ohci *ohci = fw_ohci(card);

        guard(mutex)(&ohci->phy_reg_mutex);

        return update_phy_reg(ohci, addr, clear_bits, set_bits);
}

static void ar_context_link_page(struct ar_context *ctx, unsigned int index)
{
        struct descriptor *d;

        d = &ctx->descriptors[index];
        d->branch_address  &= cpu_to_le32(~0xf);
        d->res_count       =  cpu_to_le16(PAGE_SIZE);
        d->transfer_status =  0;

        wmb(); /* finish init of new descriptors before branch_address update */
        d = &ctx->descriptors[ctx->last_buffer_index];
        d->branch_address  |= cpu_to_le32(1);

        ctx->last_buffer_index = index;

        reg_write(ctx->ohci, CONTROL_SET(ctx->regs), CONTEXT_WAKE);
}

static void ar_context_release(struct ar_context *ctx)
{
        struct device *dev = ctx->ohci->card.device;

        if (!ctx->buffer)
                return;

        for (int i = 0; i < AR_BUFFERS; ++i) {
                dma_addr_t dma_addr = ctx->dma_addrs[i];
                if (dma_addr)
                        dma_unmap_page(dev, dma_addr, PAGE_SIZE, DMA_FROM_DEVICE);
        }
        memset(ctx->dma_addrs, 0, sizeof(ctx->dma_addrs));

        vunmap(ctx->buffer);
        ctx->buffer = NULL;

        release_pages(ctx->pages, AR_BUFFERS);
        memset(ctx->pages, 0, sizeof(ctx->pages));
}

static void ar_context_abort(struct ar_context *ctx, const char *error_msg)
{
        struct fw_ohci *ohci = ctx->ohci;

        if (reg_read(ohci, CONTROL_CLEAR(ctx->regs)) & CONTEXT_RUN) {
                reg_write(ohci, CONTROL_CLEAR(ctx->regs), CONTEXT_RUN);
                flush_writes(ohci);

                ohci_err(ohci, "AR error: %s; DMA stopped\n", error_msg);
        }
        /* FIXME: restart? */
}

static inline unsigned int ar_next_buffer_index(unsigned int index)
{
        return (index + 1) % AR_BUFFERS;
}

static inline unsigned int ar_first_buffer_index(struct ar_context *ctx)
{
        return ar_next_buffer_index(ctx->last_buffer_index);
}

/*
 * We search for the buffer that contains the last AR packet DMA data written
 * by the controller.
 */
static unsigned int ar_search_last_active_buffer(struct ar_context *ctx,
                                                 unsigned int *buffer_offset)
{
        unsigned int i, next_i, last = ctx->last_buffer_index;
        __le16 res_count, next_res_count;

        i = ar_first_buffer_index(ctx);
        res_count = READ_ONCE(ctx->descriptors[i].res_count);

        /* A buffer that is not yet completely filled must be the last one. */
        while (i != last && res_count == 0) {

                /* Peek at the next descriptor. */
                next_i = ar_next_buffer_index(i);
                rmb(); /* read descriptors in order */
                next_res_count = READ_ONCE(ctx->descriptors[next_i].res_count);
                /*
                 * If the next descriptor is still empty, we must stop at this
                 * descriptor.
                 */
                if (next_res_count == cpu_to_le16(PAGE_SIZE)) {
                        /*
                         * The exception is when the DMA data for one packet is
                         * split over three buffers; in this case, the middle
                         * buffer's descriptor might be never updated by the
                         * controller and look still empty, and we have to peek
                         * at the third one.
                         */
                        if (MAX_AR_PACKET_SIZE > PAGE_SIZE && i != last) {
                                next_i = ar_next_buffer_index(next_i);
                                rmb();
                                next_res_count = READ_ONCE(ctx->descriptors[next_i].res_count);
                                if (next_res_count != cpu_to_le16(PAGE_SIZE))
                                        goto next_buffer_is_active;
                        }

                        break;
                }

next_buffer_is_active:
                i = next_i;
                res_count = next_res_count;
        }

        rmb(); /* read res_count before the DMA data */

        *buffer_offset = PAGE_SIZE - le16_to_cpu(res_count);
        if (*buffer_offset > PAGE_SIZE) {
                *buffer_offset = 0;
                ar_context_abort(ctx, "corrupted descriptor");
        }

        return i;
}

static void ar_sync_buffers_for_cpu(struct ar_context *ctx,
                                    unsigned int end_buffer_index,
                                    unsigned int end_buffer_offset)
{
        unsigned int i;

        i = ar_first_buffer_index(ctx);
        while (i != end_buffer_index) {
                dma_sync_single_for_cpu(ctx->ohci->card.device, ctx->dma_addrs[i], PAGE_SIZE,
                                        DMA_FROM_DEVICE);
                i = ar_next_buffer_index(i);
        }
        if (end_buffer_offset > 0)
                dma_sync_single_for_cpu(ctx->ohci->card.device, ctx->dma_addrs[i],
                                        end_buffer_offset, DMA_FROM_DEVICE);
}

#if defined(CONFIG_PPC_PMAC) && defined(CONFIG_PPC32)
static u32 cond_le32_to_cpu(__le32 value, bool has_be_header_quirk)
{
        return has_be_header_quirk ? (__force __u32)value : le32_to_cpu(value);
}

static bool has_be_header_quirk(const struct fw_ohci *ohci)
{
        return !!(ohci->quirks & QUIRK_BE_HEADERS);
}
#else
static u32 cond_le32_to_cpu(__le32 value, bool has_be_header_quirk __maybe_unused)
{
        return le32_to_cpu(value);
}

static bool has_be_header_quirk(const struct fw_ohci *ohci)
{
        return false;
}
#endif

static __le32 *handle_ar_packet(struct ar_context *ctx, __le32 *buffer)
{
        struct fw_ohci *ohci = ctx->ohci;
        struct fw_packet p;
        u32 status, length, tcode;
        int evt;

        p.header[0] = cond_le32_to_cpu(buffer[0], has_be_header_quirk(ohci));
        p.header[1] = cond_le32_to_cpu(buffer[1], has_be_header_quirk(ohci));
        p.header[2] = cond_le32_to_cpu(buffer[2], has_be_header_quirk(ohci));

        tcode = async_header_get_tcode(p.header);
        switch (tcode) {
        case TCODE_WRITE_QUADLET_REQUEST:
        case TCODE_READ_QUADLET_RESPONSE:
                p.header[3] = (__force __u32) buffer[3];
                p.header_length = 16;
                p.payload_length = 0;
                break;

        case TCODE_READ_BLOCK_REQUEST :
                p.header[3] = cond_le32_to_cpu(buffer[3], has_be_header_quirk(ohci));
                p.header_length = 16;
                p.payload_length = 0;
                break;

        case TCODE_WRITE_BLOCK_REQUEST:
        case TCODE_READ_BLOCK_RESPONSE:
        case TCODE_LOCK_REQUEST:
        case TCODE_LOCK_RESPONSE:
                p.header[3] = cond_le32_to_cpu(buffer[3], has_be_header_quirk(ohci));
                p.header_length = 16;
                p.payload_length = async_header_get_data_length(p.header);
                if (p.payload_length > MAX_ASYNC_PAYLOAD) {
                        ar_context_abort(ctx, "invalid packet length");
                        return NULL;
                }
                break;

        case TCODE_WRITE_RESPONSE:
        case TCODE_READ_QUADLET_REQUEST:
        case TCODE_LINK_INTERNAL:
                p.header_length = 12;
                p.payload_length = 0;
                break;

        default:
                ar_context_abort(ctx, "invalid tcode");
                return NULL;
        }

        p.payload = (void *) buffer + p.header_length;

        /* FIXME: What to do about evt_* errors? */
        length = (p.header_length + p.payload_length + 3) / 4;
        status = cond_le32_to_cpu(buffer[length], has_be_header_quirk(ohci));
        evt    = (status >> 16) & 0x1f;

        p.ack        = evt - 16;
        p.speed      = (status >> 21) & 0x7;
        p.timestamp  = status & 0xffff;
        p.generation = ohci->request_generation;

        /*
         * Several controllers, notably from NEC and VIA, forget to
         * write ack_complete status at PHY packet reception.
         */
        if (evt == OHCI1394_evt_no_status && tcode == TCODE_LINK_INTERNAL)
                p.ack = ACK_COMPLETE;

        /*
         * The OHCI bus reset handler synthesizes a PHY packet with
         * the new generation number when a bus reset happens (see
         * section 8.4.2.3).  This helps us determine when a request
         * was received and make sure we send the response in the same
         * generation.  We only need this for requests; for responses
         * we use the unique tlabel for finding the matching
         * request.
         *
         * Alas some chips sometimes emit bus reset packets with a
         * wrong generation.  We set the correct generation for these
         * at a slightly incorrect time (in handle_selfid_complete_event).
         */
        if (evt == OHCI1394_evt_bus_reset) {
                if (!(ohci->quirks & QUIRK_RESET_PACKET))
                        ohci->request_generation = (p.header[2] >> 16) & 0xff;
        } else if (ctx == &ohci->ar_request_ctx) {
                fw_core_handle_request(&ohci->card, &p);
        } else {
                fw_core_handle_response(&ohci->card, &p);
        }

        return buffer + length + 1;
}

static void *handle_ar_packets(struct ar_context *ctx, void *p, void *end)
{
        void *next;

        while (p < end) {
                next = handle_ar_packet(ctx, p);
                if (!next)
                        return p;
                p = next;
        }

        return p;
}

static void ar_recycle_buffers(struct ar_context *ctx, unsigned int end_buffer)
{
        unsigned int i;

        i = ar_first_buffer_index(ctx);
        while (i != end_buffer) {
                dma_sync_single_for_device(ctx->ohci->card.device, ctx->dma_addrs[i], PAGE_SIZE,
                                           DMA_FROM_DEVICE);
                ar_context_link_page(ctx, i);
                i = ar_next_buffer_index(i);
        }
}

static void ohci_ar_context_work(struct work_struct *work)
{
        struct ar_context *ctx = from_work(ctx, work, work);
        unsigned int end_buffer_index, end_buffer_offset;
        void *p, *end;

        p = ctx->pointer;
        if (!p)
                return;

        end_buffer_index = ar_search_last_active_buffer(ctx, &end_buffer_offset);
        ar_sync_buffers_for_cpu(ctx, end_buffer_index, end_buffer_offset);
        end = ctx->buffer + end_buffer_index * PAGE_SIZE + end_buffer_offset;

        if (end_buffer_index < ar_first_buffer_index(ctx)) {
                // The filled part of the overall buffer wraps around; handle all packets up to the
                // buffer end here.  If the last packet wraps around, its tail will be visible after
                // the buffer end because the buffer start pages are mapped there again.
                void *buffer_end = ctx->buffer + AR_BUFFERS * PAGE_SIZE;
                p = handle_ar_packets(ctx, p, buffer_end);
                if (p < buffer_end)
                        goto error;
                // adjust p to point back into the actual buffer
                p -= AR_BUFFERS * PAGE_SIZE;
        }

        p = handle_ar_packets(ctx, p, end);
        if (p != end) {
                if (p > end)
                        ar_context_abort(ctx, "inconsistent descriptor");
                goto error;
        }

        ctx->pointer = p;
        ar_recycle_buffers(ctx, end_buffer_index);

        return;
error:
        ctx->pointer = NULL;
}

static int ar_context_init(struct ar_context *ctx, struct fw_ohci *ohci,
                           unsigned int descriptors_offset, u32 regs)
{
        struct device *dev = ohci->card.device;
        unsigned int i;
        struct page *pages[AR_BUFFERS + AR_WRAPAROUND_PAGES] = { NULL };
        dma_addr_t dma_addrs[AR_BUFFERS];
        void *vaddr;
        struct descriptor *d;

        ctx->regs        = regs;
        ctx->ohci        = ohci;
        INIT_WORK(&ctx->work, ohci_ar_context_work);

        // Retrieve noncontiguous pages. The descriptors for 1394 OHCI AR DMA contexts have a set
        // of address and length per each. The reason to use pages is to construct contiguous
        // address range in kernel virtual address space.
        unsigned long nr_populated = alloc_pages_bulk(GFP_KERNEL | GFP_DMA32, AR_BUFFERS, pages);

        if (nr_populated != AR_BUFFERS) {
                release_pages(pages, nr_populated);
                return -ENOMEM;
        }

        // Map the pages into contiguous kernel virtual addresses so that the packet data
        // across the pages can be referred as being contiguous, especially across the last
        // and first pages.
        for (i = 0; i < AR_WRAPAROUND_PAGES; i++)
                pages[AR_BUFFERS + i] = pages[i];
        vaddr = vmap(pages, ARRAY_SIZE(pages), VM_MAP, PAGE_KERNEL);
        if (!vaddr) {
                release_pages(pages, nr_populated);
                return -ENOMEM;
        }

        // Retrieve DMA mapping addresses for the pages. They are not contiguous. Maintain the cache
        // coherency for the pages by hand.
        for (i = 0; i < AR_BUFFERS; i++) {
                // The dma_map_phys() with a physical address per page is available here, instead.
                dma_addr_t dma_addr = dma_map_page(dev, pages[i], 0, PAGE_SIZE, DMA_FROM_DEVICE);
                if (dma_mapping_error(dev, dma_addr))
                        break;
                dma_addrs[i] = dma_addr;
                dma_sync_single_for_device(dev, dma_addr, PAGE_SIZE, DMA_FROM_DEVICE);
        }
        if (i < AR_BUFFERS) {
                while (i-- > 0)
                        dma_unmap_page(dev, dma_addrs[i], PAGE_SIZE, DMA_FROM_DEVICE);
                vunmap(vaddr);
                release_pages(pages, nr_populated);
                return -ENOMEM;
        }

        memcpy(ctx->dma_addrs, dma_addrs, sizeof(ctx->dma_addrs));
        ctx->buffer = vaddr;
        memcpy(ctx->pages, pages, sizeof(ctx->pages));

        ctx->descriptors     = ohci->misc_buffer     + descriptors_offset;
        ctx->descriptors_bus = ohci->misc_buffer_bus + descriptors_offset;

        for (i = 0; i < AR_BUFFERS; i++) {
                d = &ctx->descriptors[i];
                d->req_count      = cpu_to_le16(PAGE_SIZE);
                d->control        = cpu_to_le16(DESCRIPTOR_INPUT_MORE |
                                                DESCRIPTOR_STATUS |
                                                DESCRIPTOR_BRANCH_ALWAYS);
                d->data_address   = cpu_to_le32(ctx->dma_addrs[i]);
                d->branch_address = cpu_to_le32(ctx->descriptors_bus +
                        ar_next_buffer_index(i) * sizeof(struct descriptor));
        }

        return 0;
}

static void ar_context_run(struct ar_context *ctx)
{
        unsigned int i;

        for (i = 0; i < AR_BUFFERS; i++)
                ar_context_link_page(ctx, i);

        ctx->pointer = ctx->buffer;

        reg_write(ctx->ohci, COMMAND_PTR(ctx->regs), ctx->descriptors_bus | 1);
        reg_write(ctx->ohci, CONTROL_SET(ctx->regs), CONTEXT_RUN);
}

static struct descriptor *find_branch_descriptor(struct descriptor *d, int z)
{
        __le16 branch;

        branch = d->control & cpu_to_le16(DESCRIPTOR_BRANCH_ALWAYS);

        /* figure out which descriptor the branch address goes in */
        if (z == 2 && branch == cpu_to_le16(DESCRIPTOR_BRANCH_ALWAYS))
                return d;
        else
                return d + z - 1;
}

static void context_retire_descriptors(struct context *ctx)
{
        struct descriptor *d, *last;
        u32 address;
        int z;
        struct descriptor_buffer *desc;

        desc = list_entry(ctx->buffer_list.next,
                        struct descriptor_buffer, list);
        last = ctx->last;
        while (last->branch_address != 0) {
                struct descriptor_buffer *old_desc = desc;
                address = le32_to_cpu(last->branch_address);
                z = address & 0xf;
                address &= ~0xf;
                ctx->current_bus = address;

                /* If the branch address points to a buffer outside of the
                 * current buffer, advance to the next buffer. */
                if (address < desc->buffer_bus ||
                                address >= desc->buffer_bus + desc->used)
                        desc = list_entry(desc->list.next,
                                        struct descriptor_buffer, list);
                d = desc->buffer + (address - desc->buffer_bus) / sizeof(*d);
                last = find_branch_descriptor(d, z);

                if (!ctx->callback(ctx, d, last))
                        break;

                if (old_desc != desc) {
                        // If we've advanced to the next buffer, move the previous buffer to the
                        // free list.
                        old_desc->used = 0;
                        guard(spinlock_irqsave)(&ctx->ohci->lock);
                        list_move_tail(&old_desc->list, &ctx->buffer_list);
                }
                ctx->last = last;
        }
}

static void ohci_at_context_work(struct work_struct *work)
{
        struct at_context *ctx = from_work(ctx, work, work);

        context_retire_descriptors(&ctx->context);
}

static void ohci_isoc_context_work(struct work_struct *work)
{
        struct fw_iso_context *base = from_work(base, work, work);
        struct iso_context *isoc_ctx = container_of(base, struct iso_context, base);

        context_retire_descriptors(&isoc_ctx->context);
}

/*
 * Allocate a new buffer and add it to the list of free buffers for this
 * context.  Must be called with ohci->lock held.
 */
static int context_add_buffer(struct context *ctx)
{
        struct descriptor_buffer *desc;
        dma_addr_t bus_addr;
        int offset;

        /*
         * 16MB of descriptors should be far more than enough for any DMA
         * program.  This will catch run-away userspace or DoS attacks.
         */
        if (ctx->total_allocation >= 16*1024*1024)
                return -ENOMEM;

        desc = dmam_alloc_coherent(ctx->ohci->card.device, PAGE_SIZE, &bus_addr, GFP_ATOMIC);
        if (!desc)
                return -ENOMEM;

        offset = (void *)&desc->buffer - (void *)desc;
        /*
         * Some controllers, like JMicron ones, always issue 0x20-byte DMA reads
         * for descriptors, even 0x10-byte ones. This can cause page faults when
         * an IOMMU is in use and the oversized read crosses a page boundary.
         * Work around this by always leaving at least 0x10 bytes of padding.
         */
        desc->buffer_size = PAGE_SIZE - offset - 0x10;
        desc->buffer_bus = bus_addr + offset;
        desc->used = 0;

        list_add_tail(&desc->list, &ctx->buffer_list);
        ctx->total_allocation += PAGE_SIZE;

        return 0;
}

static int context_init(struct context *ctx, struct fw_ohci *ohci,
                        u32 regs, descriptor_callback_t callback)
{
        ctx->ohci = ohci;
        ctx->regs = regs;
        ctx->total_allocation = 0;

        INIT_LIST_HEAD(&ctx->buffer_list);
        if (context_add_buffer(ctx) < 0)
                return -ENOMEM;

        ctx->buffer_tail = list_entry(ctx->buffer_list.next,
                        struct descriptor_buffer, list);

        ctx->callback = callback;

        /*
         * We put a dummy descriptor in the buffer that has a NULL
         * branch address and looks like it's been sent.  That way we
         * have a descriptor to append DMA programs to.
         */
        memset(ctx->buffer_tail->buffer, 0, sizeof(*ctx->buffer_tail->buffer));
        ctx->buffer_tail->buffer->control = cpu_to_le16(DESCRIPTOR_OUTPUT_LAST);
        ctx->buffer_tail->buffer->transfer_status = cpu_to_le16(0x8011);
        ctx->buffer_tail->used += sizeof(*ctx->buffer_tail->buffer);
        ctx->last = ctx->buffer_tail->buffer;
        ctx->prev = ctx->buffer_tail->buffer;
        ctx->prev_z = 1;

        return 0;
}

static void context_release(struct context *ctx)
{
        struct fw_card *card = &ctx->ohci->card;
        struct descriptor_buffer *desc, *tmp;

        list_for_each_entry_safe(desc, tmp, &ctx->buffer_list, list) {
                dmam_free_coherent(card->device, PAGE_SIZE, desc,
                                   desc->buffer_bus - ((void *)&desc->buffer - (void *)desc));
        }
}

/* Must be called with ohci->lock held */
static struct descriptor *context_get_descriptors(struct context *ctx,
                                                  int z, dma_addr_t *d_bus)
{
        struct descriptor *d = NULL;
        struct descriptor_buffer *desc = ctx->buffer_tail;

        if (z * sizeof(*d) > desc->buffer_size)
                return NULL;

        if (z * sizeof(*d) > desc->buffer_size - desc->used) {
                /* No room for the descriptor in this buffer, so advance to the
                 * next one. */

                if (desc->list.next == &ctx->buffer_list) {
                        /* If there is no free buffer next in the list,
                         * allocate one. */
                        if (context_add_buffer(ctx) < 0)
                                return NULL;
                }
                desc = list_entry(desc->list.next,
                                struct descriptor_buffer, list);
                ctx->buffer_tail = desc;
        }

        d = desc->buffer + desc->used / sizeof(*d);
        memset(d, 0, z * sizeof(*d));
        *d_bus = desc->buffer_bus + desc->used;

        return d;
}

static void context_run(struct context *ctx, u32 extra)
{
        struct fw_ohci *ohci = ctx->ohci;

        reg_write(ohci, COMMAND_PTR(ctx->regs),
                  le32_to_cpu(ctx->last->branch_address));
        reg_write(ohci, CONTROL_CLEAR(ctx->regs), ~0);
        reg_write(ohci, CONTROL_SET(ctx->regs), CONTEXT_RUN | extra);
        ctx->running = true;
        flush_writes(ohci);
}

static void context_append(struct context *ctx,
                           struct descriptor *d, int z, int extra)
{
        dma_addr_t d_bus;
        struct descriptor_buffer *desc = ctx->buffer_tail;
        struct descriptor *d_branch;

        d_bus = desc->buffer_bus + (d - desc->buffer) * sizeof(*d);

        desc->used += (z + extra) * sizeof(*d);

        wmb(); /* finish init of new descriptors before branch_address update */

        d_branch = find_branch_descriptor(ctx->prev, ctx->prev_z);
        d_branch->branch_address = cpu_to_le32(d_bus | z);

        /*
         * VT6306 incorrectly checks only the single descriptor at the
         * CommandPtr when the wake bit is written, so if it's a
         * multi-descriptor block starting with an INPUT_MORE, put a copy of
         * the branch address in the first descriptor.
         *
         * Not doing this for transmit contexts since not sure how it interacts
         * with skip addresses.
         */
        if (unlikely(ctx->ohci->quirks & QUIRK_IR_WAKE) &&
            d_branch != ctx->prev &&
            (ctx->prev->control & cpu_to_le16(DESCRIPTOR_CMD)) ==
             cpu_to_le16(DESCRIPTOR_INPUT_MORE)) {
                ctx->prev->branch_address = cpu_to_le32(d_bus | z);
        }

        ctx->prev = d;
        ctx->prev_z = z;
}

static void context_stop(struct context *ctx)
{
        struct fw_ohci *ohci = ctx->ohci;
        u32 reg;
        int i;

        reg_write(ohci, CONTROL_CLEAR(ctx->regs), CONTEXT_RUN);
        ctx->running = false;

        for (i = 0; i < 1000; i++) {
                reg = reg_read(ohci, CONTROL_SET(ctx->regs));
                if ((reg & CONTEXT_ACTIVE) == 0)
                        return;

                if (i)
                        udelay(10);
        }
        ohci_err(ohci, "DMA context still active (0x%08x)\n", reg);
}

struct driver_data {
        u8 inline_data[8];
        struct fw_packet *packet;
};

/*
 * This function appends a packet to the DMA queue for transmission.
 * Must always be called with the ochi->lock held to ensure proper
 * generation handling and locking around packet queue manipulation.
 */
static int at_context_queue_packet(struct at_context *ctx, struct fw_packet *packet)
{
        struct context *context = &ctx->context;
        struct fw_ohci *ohci = context->ohci;
        dma_addr_t d_bus, payload_bus;
        struct driver_data *driver_data;
        struct descriptor *d, *last;
        __le32 *header;
        int z, tcode;

        d = context_get_descriptors(context, 4, &d_bus);
        if (d == NULL) {
                packet->ack = RCODE_SEND_ERROR;
                return -1;
        }

        d[0].control   = cpu_to_le16(DESCRIPTOR_KEY_IMMEDIATE);
        d[0].res_count = cpu_to_le16(packet->timestamp);

        tcode = async_header_get_tcode(packet->header);
        header = (__le32 *) &d[1];
        switch (tcode) {
        case TCODE_WRITE_QUADLET_REQUEST:
        case TCODE_WRITE_BLOCK_REQUEST:
        case TCODE_WRITE_RESPONSE:
        case TCODE_READ_QUADLET_REQUEST:
        case TCODE_READ_BLOCK_REQUEST:
        case TCODE_READ_QUADLET_RESPONSE:
        case TCODE_READ_BLOCK_RESPONSE:
        case TCODE_LOCK_REQUEST:
        case TCODE_LOCK_RESPONSE:
                ohci1394_at_data_set_src_bus_id(header, false);
                ohci1394_at_data_set_speed(header, packet->speed);
                ohci1394_at_data_set_tlabel(header, async_header_get_tlabel(packet->header));
                ohci1394_at_data_set_retry(header, async_header_get_retry(packet->header));
                ohci1394_at_data_set_tcode(header, tcode);

                ohci1394_at_data_set_destination_id(header,
                                                    async_header_get_destination(packet->header));

                if (ctx == &ohci->at_response_ctx) {
                        ohci1394_at_data_set_rcode(header, async_header_get_rcode(packet->header));
                } else {
                        ohci1394_at_data_set_destination_offset(header,
                                                        async_header_get_offset(packet->header));
                }

                if (tcode_is_block_packet(tcode))
                        header[3] = cpu_to_le32(packet->header[3]);
                else
                        header[3] = (__force __le32) packet->header[3];

                d[0].req_count = cpu_to_le16(packet->header_length);
                break;
        case TCODE_LINK_INTERNAL:
                ohci1394_at_data_set_speed(header, packet->speed);
                ohci1394_at_data_set_tcode(header, TCODE_LINK_INTERNAL);

                header[1] = cpu_to_le32(packet->header[1]);
                header[2] = cpu_to_le32(packet->header[2]);
                d[0].req_count = cpu_to_le16(12);

                if (is_ping_packet(&packet->header[1]))
                        d[0].control |= cpu_to_le16(DESCRIPTOR_PING);
                break;

        case TCODE_STREAM_DATA:
                ohci1394_it_data_set_speed(header, packet->speed);
                ohci1394_it_data_set_tag(header, isoc_header_get_tag(packet->header[0]));
                ohci1394_it_data_set_channel(header, isoc_header_get_channel(packet->header[0]));
                ohci1394_it_data_set_tcode(header, TCODE_STREAM_DATA);
                ohci1394_it_data_set_sync(header, isoc_header_get_sy(packet->header[0]));

                ohci1394_it_data_set_data_length(header, isoc_header_get_data_length(packet->header[0]));

                d[0].req_count = cpu_to_le16(8);
                break;

        default:
                /* BUG(); */
                packet->ack = RCODE_SEND_ERROR;
                return -1;
        }

        BUILD_BUG_ON(sizeof(struct driver_data) > sizeof(struct descriptor));
        driver_data = (struct driver_data *) &d[3];
        driver_data->packet = packet;
        packet->driver_data = driver_data;

        if (packet->payload_length > 0) {
                if (packet->payload_length > sizeof(driver_data->inline_data)) {
                        payload_bus = dma_map_single(ohci->card.device,
                                                     packet->payload,
                                                     packet->payload_length,
                                                     DMA_TO_DEVICE);
                        if (dma_mapping_error(ohci->card.device, payload_bus)) {
                                packet->ack = RCODE_SEND_ERROR;
                                return -1;
                        }
                        packet->payload_bus     = payload_bus;
                        packet->payload_mapped  = true;
                } else {
                        memcpy(driver_data->inline_data, packet->payload,
                               packet->payload_length);
                        payload_bus = d_bus + 3 * sizeof(*d);
                }

                d[2].req_count    = cpu_to_le16(packet->payload_length);
                d[2].data_address = cpu_to_le32(payload_bus);
                last = &d[2];
                z = 3;
        } else {
                last = &d[0];
                z = 2;
        }

        last->control |= cpu_to_le16(DESCRIPTOR_OUTPUT_LAST |
                                     DESCRIPTOR_IRQ_ALWAYS |
                                     DESCRIPTOR_BRANCH_ALWAYS);

        /* FIXME: Document how the locking works. */
        if (ohci->generation != packet->generation) {
                if (packet->payload_mapped)
                        dma_unmap_single(ohci->card.device, payload_bus,
                                         packet->payload_length, DMA_TO_DEVICE);
                packet->ack = RCODE_GENERATION;
                return -1;
        }

        context_append(context, d, z, 4 - z);

        if (context->running)
                reg_write(ohci, CONTROL_SET(context->regs), CONTEXT_WAKE);
        else
                context_run(context, 0);

        return 0;
}

static void at_context_flush(struct at_context *ctx)
{
        // Avoid dead lock due to programming mistake.
        if (WARN_ON_ONCE(current_work() == &ctx->work))
                return;

        disable_work_sync(&ctx->work);

        WRITE_ONCE(ctx->flushing, true);
        ohci_at_context_work(&ctx->work);
        WRITE_ONCE(ctx->flushing, false);

        enable_work(&ctx->work);
}

static int find_fw_device(struct device *dev, const void *data)
{
        struct fw_device *device = fw_device(dev);
        const u32 *params = data;

        return (device->generation == params[0]) && (device->node_id == params[1]);
}

static int handle_at_packet(struct context *context,
                            struct descriptor *d,
                            struct descriptor *last)
{
        struct at_context *ctx = container_of(context, struct at_context, context);
        struct fw_ohci *ohci = ctx->context.ohci;
        struct driver_data *driver_data;
        struct fw_packet *packet;
        int evt;

        if (last->transfer_status == 0 && !READ_ONCE(ctx->flushing))
                /* This descriptor isn't done yet, stop iteration. */
                return 0;

        driver_data = (struct driver_data *) &d[3];
        packet = driver_data->packet;
        if (packet == NULL)
                /* This packet was cancelled, just continue. */
                return 1;

        if (packet->payload_mapped)
                dma_unmap_single(ohci->card.device, packet->payload_bus,
                                 packet->payload_length, DMA_TO_DEVICE);

        evt = le16_to_cpu(last->transfer_status) & 0x1f;
        packet->timestamp = le16_to_cpu(last->res_count);

        switch (evt) {
        case OHCI1394_evt_timeout:
                /* Async response transmit timed out. */
                packet->ack = RCODE_CANCELLED;
                break;

        case OHCI1394_evt_flushed:
                /*
                 * The packet was flushed should give same error as
                 * when we try to use a stale generation count.
                 */
                packet->ack = RCODE_GENERATION;
                break;

        case OHCI1394_evt_missing_ack:
                if (READ_ONCE(ctx->flushing))
                        packet->ack = RCODE_GENERATION;
                else {
                        /*
                         * Using a valid (current) generation count, but the
                         * node is not on the bus or not sending acks.
                         */
                        packet->ack = RCODE_NO_ACK;
                }
                break;

        case ACK_COMPLETE + 0x10:
        case ACK_PENDING + 0x10:
        case ACK_BUSY_X + 0x10:
        case ACK_BUSY_A + 0x10:
        case ACK_BUSY_B + 0x10:
        case ACK_DATA_ERROR + 0x10:
        case ACK_TYPE_ERROR + 0x10:
                packet->ack = evt - 0x10;
                break;

        case OHCI1394_evt_no_status:
                if (READ_ONCE(ctx->flushing)) {
                        packet->ack = RCODE_GENERATION;
                        break;
                }
                fallthrough;

        default:
                if (unlikely(evt == 0x10)) {
                        u32 params[2] = {
                                packet->generation,
                                async_header_get_destination(packet->header),
                        };
                        struct device *dev;

                        fw_card_get(&ohci->card);
                        dev = device_find_child(ohci->card.device, (const void *)params, find_fw_device);
                        fw_card_put(&ohci->card);
                        if (dev) {
                                struct fw_device *device = fw_device(dev);
                                int quirks = READ_ONCE(device->quirks);

                                put_device(dev);
                                if (quirks & FW_DEVICE_QUIRK_ACK_PACKET_WITH_INVALID_PENDING_CODE) {
                                        packet->ack = ACK_PENDING;
                                        break;
                                }
                        }
                }
                packet->ack = RCODE_SEND_ERROR;
                break;
        }

        packet->callback(packet, &ohci->card, packet->ack);

        return 1;
}

static u32 get_cycle_time(struct fw_ohci *ohci);

static void handle_local_rom(struct fw_ohci *ohci,
                             struct fw_packet *packet, u32 csr)
{
        struct fw_packet response;
        int tcode, length, i;

        tcode = async_header_get_tcode(packet->header);
        if (tcode_is_block_packet(tcode))
                length = async_header_get_data_length(packet->header);
        else
                length = 4;

        i = csr - CSR_CONFIG_ROM;
        if (i + length > CONFIG_ROM_SIZE) {
                fw_fill_response(&response, packet->header,
                                 RCODE_ADDRESS_ERROR, NULL, 0);
        } else if (!tcode_is_read_request(tcode)) {
                fw_fill_response(&response, packet->header,
                                 RCODE_TYPE_ERROR, NULL, 0);
        } else {
                fw_fill_response(&response, packet->header, RCODE_COMPLETE,
                                 (void *) ohci->config_rom + i, length);
        }

        // Timestamping on behalf of the hardware.
        response.timestamp = cycle_time_to_ohci_tstamp(get_cycle_time(ohci));
        fw_core_handle_response(&ohci->card, &response);
}

static void handle_local_lock(struct fw_ohci *ohci,
                              struct fw_packet *packet, u32 csr)
{
        struct fw_packet response;
        int tcode, length, ext_tcode, sel, try;
        __be32 *payload, lock_old;
        u32 lock_arg, lock_data;

        tcode = async_header_get_tcode(packet->header);
        length = async_header_get_data_length(packet->header);
        payload = packet->payload;
        ext_tcode = async_header_get_extended_tcode(packet->header);

        if (tcode == TCODE_LOCK_REQUEST &&
            ext_tcode == EXTCODE_COMPARE_SWAP && length == 8) {
                lock_arg = be32_to_cpu(payload[0]);
                lock_data = be32_to_cpu(payload[1]);
        } else if (tcode == TCODE_READ_QUADLET_REQUEST) {
                lock_arg = 0;
                lock_data = 0;
        } else {
                fw_fill_response(&response, packet->header,
                                 RCODE_TYPE_ERROR, NULL, 0);
                goto out;
        }

        sel = (csr - CSR_BUS_MANAGER_ID) / 4;
        reg_write(ohci, OHCI1394_CSRData, lock_data);
        reg_write(ohci, OHCI1394_CSRCompareData, lock_arg);
        reg_write(ohci, OHCI1394_CSRControl, sel);

        for (try = 0; try < 20; try++)
                if (reg_read(ohci, OHCI1394_CSRControl) & 0x80000000) {
                        lock_old = cpu_to_be32(reg_read(ohci,
                                                        OHCI1394_CSRData));
                        fw_fill_response(&response, packet->header,
                                         RCODE_COMPLETE,
                                         &lock_old, sizeof(lock_old));
                        goto out;
                }

        ohci_err(ohci, "swap not done (CSR lock timeout)\n");
        fw_fill_response(&response, packet->header, RCODE_BUSY, NULL, 0);

 out:
        // Timestamping on behalf of the hardware.
        response.timestamp = cycle_time_to_ohci_tstamp(get_cycle_time(ohci));
        fw_core_handle_response(&ohci->card, &response);
}

static void handle_local_request(struct at_context *ctx, struct fw_packet *packet)
{
        struct fw_ohci *ohci = ctx->context.ohci;
        u64 offset, csr;

        if (ctx == &ohci->at_request_ctx) {
                packet->ack = ACK_PENDING;
                packet->callback(packet, &ohci->card, packet->ack);
        }

        offset = async_header_get_offset(packet->header);
        csr = offset - CSR_REGISTER_BASE;

        /* Handle config rom reads. */
        if (csr >= CSR_CONFIG_ROM && csr < CSR_CONFIG_ROM_END)
                handle_local_rom(ohci, packet, csr);
        else switch (csr) {
        case CSR_BUS_MANAGER_ID:
        case CSR_BANDWIDTH_AVAILABLE:
        case CSR_CHANNELS_AVAILABLE_HI:
        case CSR_CHANNELS_AVAILABLE_LO:
                handle_local_lock(ohci, packet, csr);
                break;
        default:
                if (ctx == &ohci->at_request_ctx)
                        fw_core_handle_request(&ohci->card, packet);
                else
                        fw_core_handle_response(&ohci->card, packet);
                break;
        }

        if (ctx == &ohci->at_response_ctx) {
                packet->ack = ACK_COMPLETE;
                packet->callback(packet, &ohci->card, packet->ack);
        }
}

static void at_context_transmit(struct at_context *ctx, struct fw_packet *packet)
{
        struct fw_ohci *ohci = ctx->context.ohci;
        unsigned long flags;
        int ret;

        spin_lock_irqsave(&ohci->lock, flags);

        if (async_header_get_destination(packet->header) == ohci->node_id &&
            ohci->generation == packet->generation) {
                spin_unlock_irqrestore(&ohci->lock, flags);

                // Timestamping on behalf of the hardware.
                packet->timestamp = cycle_time_to_ohci_tstamp(get_cycle_time(ohci));

                handle_local_request(ctx, packet);
                return;
        }

        ret = at_context_queue_packet(ctx, packet);
        spin_unlock_irqrestore(&ohci->lock, flags);

        if (ret < 0) {
                // Timestamping on behalf of the hardware.
                packet->timestamp = cycle_time_to_ohci_tstamp(get_cycle_time(ohci));

                packet->callback(packet, &ohci->card, packet->ack);
        }
}

static void detect_dead_context(struct fw_ohci *ohci,
                                const char *name, unsigned int regs)
{
        static const char *const evts[] = {
                [0x00] = "evt_no_status",       [0x01] = "-reserved-",
                [0x02] = "evt_long_packet",     [0x03] = "evt_missing_ack",
                [0x04] = "evt_underrun",        [0x05] = "evt_overrun",
                [0x06] = "evt_descriptor_read", [0x07] = "evt_data_read",
                [0x08] = "evt_data_write",      [0x09] = "evt_bus_reset",
                [0x0a] = "evt_timeout",         [0x0b] = "evt_tcode_err",
                [0x0c] = "-reserved-",          [0x0d] = "-reserved-",
                [0x0e] = "evt_unknown",         [0x0f] = "evt_flushed",
                [0x10] = "-reserved-",          [0x11] = "ack_complete",
                [0x12] = "ack_pending ",        [0x13] = "-reserved-",
                [0x14] = "ack_busy_X",          [0x15] = "ack_busy_A",
                [0x16] = "ack_busy_B",          [0x17] = "-reserved-",
                [0x18] = "-reserved-",          [0x19] = "-reserved-",
                [0x1a] = "-reserved-",          [0x1b] = "ack_tardy",
                [0x1c] = "-reserved-",          [0x1d] = "ack_data_error",
                [0x1e] = "ack_type_error",      [0x1f] = "-reserved-",
                [0x20] = "pending/cancelled",
        };
        u32 ctl;

        ctl = reg_read(ohci, CONTROL_SET(regs));
        if (ctl & CONTEXT_DEAD)
                ohci_err(ohci, "DMA context %s has stopped, error code: %s\n",
                        name, evts[ctl & 0x1f]);
}

static void handle_dead_contexts(struct fw_ohci *ohci)
{
        unsigned int i;
        char name[8];

        detect_dead_context(ohci, "ATReq", OHCI1394_AsReqTrContextBase);
        detect_dead_context(ohci, "ATRsp", OHCI1394_AsRspTrContextBase);
        detect_dead_context(ohci, "ARReq", OHCI1394_AsReqRcvContextBase);
        detect_dead_context(ohci, "ARRsp", OHCI1394_AsRspRcvContextBase);
        for (i = 0; i < 32; ++i) {
                if (!(ohci->it_context_support & (1 << i)))
                        continue;
                sprintf(name, "IT%u", i);
                detect_dead_context(ohci, name, OHCI1394_IsoXmitContextBase(i));
        }
        for (i = 0; i < 32; ++i) {
                if (!(ohci->ir_context_support & (1 << i)))
                        continue;
                sprintf(name, "IR%u", i);
                detect_dead_context(ohci, name, OHCI1394_IsoRcvContextBase(i));
        }
        /* TODO: maybe try to flush and restart the dead contexts */
}

static u32 cycle_timer_ticks(u32 cycle_timer)
{
        u32 ticks;

        ticks = cycle_timer & 0xfff;
        ticks += 3072 * ((cycle_timer >> 12) & 0x1fff);
        ticks += (3072 * 8000) * (cycle_timer >> 25);

        return ticks;
}

/*
 * Some controllers exhibit one or more of the following bugs when updating the
 * iso cycle timer register:
 *  - When the lowest six bits are wrapping around to zero, a read that happens
 *    at the same time will return garbage in the lowest ten bits.
 *  - When the cycleOffset field wraps around to zero, the cycleCount field is
 *    not incremented for about 60 ns.
 *  - Occasionally, the entire register reads zero.
 *
 * To catch these, we read the register three times and ensure that the
 * difference between each two consecutive reads is approximately the same, i.e.
 * less than twice the other.  Furthermore, any negative difference indicates an
 * error.  (A PCI read should take at least 20 ticks of the 24.576 MHz timer to
 * execute, so we have enough precision to compute the ratio of the differences.)
 */
static u32 get_cycle_time(struct fw_ohci *ohci)
{
        u32 c0, c1, c2;
        u32 t0, t1, t2;
        s32 diff01, diff12;
        int i;

        if (has_reboot_by_cycle_timer_read_quirk(ohci))
                return 0;

        c2 = reg_read(ohci, OHCI1394_IsochronousCycleTimer);

        if (ohci->quirks & QUIRK_CYCLE_TIMER) {
                i = 0;
                c1 = c2;
                c2 = reg_read(ohci, OHCI1394_IsochronousCycleTimer);
                do {
                        c0 = c1;
                        c1 = c2;
                        c2 = reg_read(ohci, OHCI1394_IsochronousCycleTimer);
                        t0 = cycle_timer_ticks(c0);
                        t1 = cycle_timer_ticks(c1);
                        t2 = cycle_timer_ticks(c2);
                        diff01 = t1 - t0;
                        diff12 = t2 - t1;
                } while ((diff01 <= 0 || diff12 <= 0 ||
                          diff01 / diff12 >= 2 || diff12 / diff01 >= 2)
                         && i++ < 20);
        }

        return c2;
}

/*
 * This function has to be called at least every 64 seconds.  The bus_time
 * field stores not only the upper 25 bits of the BUS_TIME register but also
 * the most significant bit of the cycle timer in bit 6 so that we can detect
 * changes in this bit.
 */
static u32 update_bus_time(struct fw_ohci *ohci)
{
        u32 cycle_time_seconds = get_cycle_time(ohci) >> 25;

        if (unlikely(!ohci->bus_time_running)) {
                reg_write(ohci, OHCI1394_IntMaskSet, OHCI1394_cycle64Seconds);
                ohci->bus_time = (lower_32_bits(ktime_get_seconds()) & ~0x7f) |
                                 (cycle_time_seconds & 0x40);
                ohci->bus_time_running = true;
        }

        if ((ohci->bus_time & 0x40) != (cycle_time_seconds & 0x40))
                ohci->bus_time += 0x40;

        return ohci->bus_time | cycle_time_seconds;
}

static int get_status_for_port(struct fw_ohci *ohci, int port_index,
                               enum phy_packet_self_id_port_status *status)
{
        int reg;

        scoped_guard(mutex, &ohci->phy_reg_mutex) {
                reg = write_phy_reg(ohci, 7, port_index);
                if (reg < 0)
                        return reg;

                reg = read_phy_reg(ohci, 8);
                if (reg < 0)
                        return reg;
        }

        switch (reg & 0x0f) {
        case 0x06:
                // is child node (connected to parent node)
                *status = PHY_PACKET_SELF_ID_PORT_STATUS_PARENT;
                break;
        case 0x0e:
                // is parent node (connected to child node)
                *status = PHY_PACKET_SELF_ID_PORT_STATUS_CHILD;
                break;
        default:
                // not connected
                *status = PHY_PACKET_SELF_ID_PORT_STATUS_NCONN;
                break;
        }

        return 0;
}

static int get_self_id_pos(struct fw_ohci *ohci, u32 self_id,
        int self_id_count)
{
        unsigned int left_phy_id = phy_packet_self_id_get_phy_id(self_id);
        int i;

        for (i = 0; i < self_id_count; i++) {
                u32 entry = ohci->self_id_buffer[i];
                unsigned int right_phy_id = phy_packet_self_id_get_phy_id(entry);

                if (left_phy_id == right_phy_id)
                        return -1;
                if (left_phy_id < right_phy_id)
                        return i;
        }
        return i;
}

static int detect_initiated_reset(struct fw_ohci *ohci, bool *is_initiated_reset)
{
        int reg;

        guard(mutex)(&ohci->phy_reg_mutex);

        // Select page 7
        reg = write_phy_reg(ohci, 7, 0xe0);
        if (reg < 0)
                return reg;

        reg = read_phy_reg(ohci, 8);
        if (reg < 0)
                return reg;

        // set PMODE bit
        reg |= 0x40;
        reg = write_phy_reg(ohci, 8, reg);
        if (reg < 0)
                return reg;

        // read register 12
        reg = read_phy_reg(ohci, 12);
        if (reg < 0)
                return reg;

        // bit 3 indicates "initiated reset"
        *is_initiated_reset = !!((reg & 0x08) == 0x08);

        return 0;
}

/*
 * TI TSB82AA2B and TSB12LV26 do not receive the selfID of a locally
 * attached TSB41BA3D phy; see http://www.ti.com/litv/pdf/sllz059.
 * Construct the selfID from phy register contents.
 */
static int find_and_insert_self_id(struct fw_ohci *ohci, int self_id_count)
{
        int reg, i, pos, err;
        bool is_initiated_reset;
        u32 self_id = 0;

        // link active 1, speed 3, bridge 0, contender 1, more packets 0.
        phy_packet_set_packet_identifier(&self_id, PHY_PACKET_PACKET_IDENTIFIER_SELF_ID);
        phy_packet_self_id_zero_set_link_active(&self_id, true);
        phy_packet_self_id_zero_set_scode(&self_id, SCODE_800);
        phy_packet_self_id_zero_set_contender(&self_id, true);

        reg = reg_read(ohci, OHCI1394_NodeID);
        if (!(reg & OHCI1394_NodeID_idValid)) {
                ohci_notice(ohci,
                            "node ID not valid, new bus reset in progress\n");
                return -EBUSY;
        }
        phy_packet_self_id_set_phy_id(&self_id, reg & 0x3f);

        reg = ohci_read_phy_reg(&ohci->card, 4);
        if (reg < 0)
                return reg;
        phy_packet_self_id_zero_set_power_class(&self_id, reg & 0x07);

        reg = ohci_read_phy_reg(&ohci->card, 1);
        if (reg < 0)
                return reg;
        phy_packet_self_id_zero_set_gap_count(&self_id, reg & 0x3f);

        for (i = 0; i < 3; i++) {
                enum phy_packet_self_id_port_status status;

                err = get_status_for_port(ohci, i, &status);
                if (err < 0)
                        return err;

                self_id_sequence_set_port_status(&self_id, 1, i, status);
        }

        err = detect_initiated_reset(ohci, &is_initiated_reset);
        if (err < 0)
                return err;
        phy_packet_self_id_zero_set_initiated_reset(&self_id, is_initiated_reset);

        pos = get_self_id_pos(ohci, self_id, self_id_count);
        if (pos >= 0) {
                memmove(&(ohci->self_id_buffer[pos+1]),
                        &(ohci->self_id_buffer[pos]),
                        (self_id_count - pos) * sizeof(*ohci->self_id_buffer));
                ohci->self_id_buffer[pos] = self_id;
                self_id_count++;
        }
        return self_id_count;
}

static irqreturn_t handle_selfid_complete_event(int irq, void *data)
{
        struct fw_ohci *ohci = data;
        int self_id_count, generation, new_generation, i, j;
        u32 reg, quadlet;
        void *free_rom = NULL;
        dma_addr_t free_rom_bus = 0;
        bool is_new_root;

        reg = reg_read(ohci, OHCI1394_NodeID);
        if (!(reg & OHCI1394_NodeID_idValid)) {
                ohci_notice(ohci,
                            "node ID not valid, new bus reset in progress\n");
                goto end;
        }
        if ((reg & OHCI1394_NodeID_nodeNumber) == 63) {
                ohci_notice(ohci, "malconfigured bus\n");
                goto end;
        }
        ohci->node_id = reg & (OHCI1394_NodeID_busNumber |
                               OHCI1394_NodeID_nodeNumber);

        is_new_root = (reg & OHCI1394_NodeID_root) != 0;
        if (!(ohci->is_root && is_new_root))
                reg_write(ohci, OHCI1394_LinkControlSet,
                          OHCI1394_LinkControl_cycleMaster);
        ohci->is_root = is_new_root;

        reg = reg_read(ohci, OHCI1394_SelfIDCount);
        if (ohci1394_self_id_count_is_error(reg)) {
                ohci_notice(ohci, "self ID receive error\n");
                goto end;
        }

        trace_self_id_complete(ohci->card.index, reg, ohci->self_id, has_be_header_quirk(ohci));

        /*
         * The count in the SelfIDCount register is the number of
         * bytes in the self ID receive buffer.  Since we also receive
         * the inverted quadlets and a header quadlet, we shift one
         * bit extra to get the actual number of self IDs.
         */
        self_id_count = ohci1394_self_id_count_get_size(reg) >> 1;

        if (self_id_count > 252) {
                ohci_notice(ohci, "bad selfIDSize (%08x)\n", reg);
                goto end;
        }

        quadlet = cond_le32_to_cpu(ohci->self_id[0], has_be_header_quirk(ohci));
        generation = ohci1394_self_id_receive_q0_get_generation(quadlet);
        rmb();

        for (i = 1, j = 0; j < self_id_count; i += 2, j++) {
                u32 id  = cond_le32_to_cpu(ohci->self_id[i], has_be_header_quirk(ohci));
                u32 id2 = cond_le32_to_cpu(ohci->self_id[i + 1], has_be_header_quirk(ohci));

                if (id != ~id2) {
                        /*
                         * If the invalid data looks like a cycle start packet,
                         * it's likely to be the result of the cycle master
                         * having a wrong gap count.  In this case, the self IDs
                         * so far are valid and should be processed so that the
                         * bus manager can then correct the gap count.
                         */
                        if (id == 0xffff008f) {
                                ohci_notice(ohci, "ignoring spurious self IDs\n");
                                self_id_count = j;
                                break;
                        }

                        ohci_notice(ohci, "bad self ID %d/%d (%08x != ~%08x)\n",
                                    j, self_id_count, id, id2);
                        goto end;
                }
                ohci->self_id_buffer[j] = id;
        }

        if (ohci->quirks & QUIRK_TI_SLLZ059) {
                self_id_count = find_and_insert_self_id(ohci, self_id_count);
                if (self_id_count < 0) {
                        ohci_notice(ohci,
                                    "could not construct local self ID\n");
                        goto end;
                }
        }

        if (self_id_count == 0) {
                ohci_notice(ohci, "no self IDs\n");
                goto end;
        }
        rmb();

        /*
         * Check the consistency of the self IDs we just read.  The
         * problem we face is that a new bus reset can start while we
         * read out the self IDs from the DMA buffer. If this happens,
         * the DMA buffer will be overwritten with new self IDs and we
         * will read out inconsistent data.  The OHCI specification
         * (section 11.2) recommends a technique similar to
         * linux/seqlock.h, where we remember the generation of the
         * self IDs in the buffer before reading them out and compare
         * it to the current generation after reading them out.  If
         * the two generations match we know we have a consistent set
         * of self IDs.
         */

        reg = reg_read(ohci, OHCI1394_SelfIDCount);
        new_generation = ohci1394_self_id_count_get_generation(reg);
        if (new_generation != generation) {
                ohci_notice(ohci, "new bus reset, discarding self ids\n");
                goto end;
        }

        // FIXME: Document how the locking works.
        scoped_guard(spinlock_irq, &ohci->lock) {
                ohci->generation = -1; // prevent AT packet queueing
                context_stop(&ohci->at_request_ctx.context);
                context_stop(&ohci->at_response_ctx.context);
        }

        /*
         * Per OHCI 1.2 draft, clause 7.2.3.3, hardware may leave unsent
         * packets in the AT queues and software needs to drain them.
         * Some OHCI 1.1 controllers (JMicron) apparently require this too.
         */
        at_context_flush(&ohci->at_request_ctx);
        at_context_flush(&ohci->at_response_ctx);

        scoped_guard(spinlock_irq, &ohci->lock) {
                ohci->generation = generation;
                reg_write(ohci, OHCI1394_IntEventClear, OHCI1394_busReset);
                reg_write(ohci, OHCI1394_IntMaskSet, OHCI1394_busReset);

                if (ohci->quirks & QUIRK_RESET_PACKET)
                        ohci->request_generation = generation;

                // This next bit is unrelated to the AT context stuff but we have to do it under the
                // spinlock also. If a new config rom was set up before this reset, the old one is
                // now no longer in use and we can free it. Update the config rom pointers to point
                // to the current config rom and clear the next_config_rom pointer so a new update
                // can take place.
                if (ohci->next_config_rom != NULL) {
                        if (ohci->next_config_rom != ohci->config_rom) {
                                free_rom      = ohci->config_rom;
                                free_rom_bus  = ohci->config_rom_bus;
                        }
                        ohci->config_rom      = ohci->next_config_rom;
                        ohci->config_rom_bus  = ohci->next_config_rom_bus;
                        ohci->next_config_rom = NULL;

                        // Restore config_rom image and manually update config_rom registers.
                        // Writing the header quadlet will indicate that the config rom is ready,
                        // so we do that last.
                        reg_write(ohci, OHCI1394_BusOptions, be32_to_cpu(ohci->config_rom[2]));
                        ohci->config_rom[0] = ohci->next_header;
                        reg_write(ohci, OHCI1394_ConfigROMhdr, be32_to_cpu(ohci->next_header));
                }

                if (param_remote_dma) {
                        reg_write(ohci, OHCI1394_PhyReqFilterHiSet, ~0);
                        reg_write(ohci, OHCI1394_PhyReqFilterLoSet, ~0);
                }
        }

        if (free_rom)
                dmam_free_coherent(ohci->card.device, CONFIG_ROM_SIZE, free_rom, free_rom_bus);

        fw_core_handle_bus_reset(&ohci->card, ohci->node_id, generation,
                                 self_id_count, ohci->self_id_buffer,
                                 ohci->csr_state_setclear_abdicate);
        ohci->csr_state_setclear_abdicate = false;
end:
        return IRQ_HANDLED;
}

static irqreturn_t irq_handler(int irq, void *data)
{
        struct fw_ohci *ohci = data;
        u32 event, iso_event;
        int i;

        event = reg_read(ohci, OHCI1394_IntEventClear);

        if (!event || !~event)
                return IRQ_NONE;

        /*
         * busReset and postedWriteErr events must not be cleared yet
         * (OHCI 1.1 clauses 7.2.3.2 and 13.2.8.1)
         */
        reg_write(ohci, OHCI1394_IntEventClear,
                  event & ~(OHCI1394_busReset | OHCI1394_postedWriteErr));
        trace_irqs(ohci->card.index, event);

        // The flag is masked again at handle_selfid_complete_event() scheduled by selfID event.
        if (event & OHCI1394_busReset)
                reg_write(ohci, OHCI1394_IntMaskClear, OHCI1394_busReset);

        if (event & OHCI1394_RQPkt)
                queue_work(ohci->card.async_wq, &ohci->ar_request_ctx.work);

        if (event & OHCI1394_RSPkt)
                queue_work(ohci->card.async_wq, &ohci->ar_response_ctx.work);

        if (event & OHCI1394_reqTxComplete)
                queue_work(ohci->card.async_wq, &ohci->at_request_ctx.work);

        if (event & OHCI1394_respTxComplete)
                queue_work(ohci->card.async_wq, &ohci->at_response_ctx.work);

        if (event & OHCI1394_isochRx) {
                iso_event = reg_read(ohci, OHCI1394_IsoRecvIntEventClear);
                reg_write(ohci, OHCI1394_IsoRecvIntEventClear, iso_event);

                while (iso_event) {
                        i = ffs(iso_event) - 1;
                        fw_iso_context_schedule_flush_completions(&ohci->ir_context_list[i].base);
                        iso_event &= ~(1 << i);
                }
        }

        if (event & OHCI1394_isochTx) {
                iso_event = reg_read(ohci, OHCI1394_IsoXmitIntEventClear);
                reg_write(ohci, OHCI1394_IsoXmitIntEventClear, iso_event);

                while (iso_event) {
                        i = ffs(iso_event) - 1;
                        fw_iso_context_schedule_flush_completions(&ohci->it_context_list[i].base);
                        iso_event &= ~(1 << i);
                }
        }

        if (unlikely(event & OHCI1394_regAccessFail))
                ohci_err(ohci, "register access failure\n");

        if (unlikely(event & OHCI1394_postedWriteErr)) {
                reg_read(ohci, OHCI1394_PostedWriteAddressHi);
                reg_read(ohci, OHCI1394_PostedWriteAddressLo);
                reg_write(ohci, OHCI1394_IntEventClear,
                          OHCI1394_postedWriteErr);
                dev_err_ratelimited(ohci->card.device, "PCI posted write error\n");
        }

        if (unlikely(event & OHCI1394_cycleTooLong)) {
                dev_notice_ratelimited(ohci->card.device, "isochronous cycle too long\n");
                reg_write(ohci, OHCI1394_LinkControlSet,
                          OHCI1394_LinkControl_cycleMaster);
        }

        if (unlikely(event & OHCI1394_cycleInconsistent)) {
                /*
                 * We need to clear this event bit in order to make
                 * cycleMatch isochronous I/O work.  In theory we should
                 * stop active cycleMatch iso contexts now and restart
                 * them at least two cycles later.  (FIXME?)
                 */
                dev_notice_ratelimited(ohci->card.device, "isochronous cycle inconsistent\n");
        }

        if (unlikely(event & OHCI1394_unrecoverableError))
                handle_dead_contexts(ohci);

        if (event & OHCI1394_cycle64Seconds) {
                guard(spinlock)(&ohci->lock);
                update_bus_time(ohci);
        } else
                flush_writes(ohci);

        if (event & OHCI1394_selfIDComplete)
                return IRQ_WAKE_THREAD;
        else
                return IRQ_HANDLED;
}

static int software_reset(struct fw_ohci *ohci)
{
        u32 val;
        int i;

        reg_write(ohci, OHCI1394_HCControlSet, OHCI1394_HCControl_softReset);
        for (i = 0; i < 500; i++) {
                val = reg_read(ohci, OHCI1394_HCControlSet);
                if (!~val)
                        return -ENODEV; /* Card was ejected. */

                if (!(val & OHCI1394_HCControl_softReset))
                        return 0;

                msleep(1);
        }

        return -EBUSY;
}

static void copy_config_rom(__be32 *dest, const __be32 *src, size_t length)
{
        size_t size = length * 4;

        memcpy(dest, src, size);
        if (size < CONFIG_ROM_SIZE)
                memset(&dest[length], 0, CONFIG_ROM_SIZE - size);
}

static int configure_1394a_enhancements(struct fw_ohci *ohci)
{
        bool enable_1394a;
        int ret, clear, set, offset;

        /* Check if the driver should configure link and PHY. */
        if (!(reg_read(ohci, OHCI1394_HCControlSet) &
              OHCI1394_HCControl_programPhyEnable))
                return 0;

        /* Paranoia: check whether the PHY supports 1394a, too. */
        enable_1394a = false;
        ret = read_phy_reg(ohci, 2);
        if (ret < 0)
                return ret;
        if ((ret & PHY_EXTENDED_REGISTERS) == PHY_EXTENDED_REGISTERS) {
                ret = read_paged_phy_reg(ohci, 1, 8);
                if (ret < 0)
                        return ret;
                if (ret >= 1)
                        enable_1394a = true;
        }

        if (ohci->quirks & QUIRK_NO_1394A)
                enable_1394a = false;

        /* Configure PHY and link consistently. */
        if (enable_1394a) {
                clear = 0;
                set = PHY_ENABLE_ACCEL | PHY_ENABLE_MULTI;
        } else {
                clear = PHY_ENABLE_ACCEL | PHY_ENABLE_MULTI;
                set = 0;
        }
        ret = update_phy_reg(ohci, 5, clear, set);
        if (ret < 0)
                return ret;

        if (enable_1394a)
                offset = OHCI1394_HCControlSet;
        else
                offset = OHCI1394_HCControlClear;
        reg_write(ohci, offset, OHCI1394_HCControl_aPhyEnhanceEnable);

        /* Clean up: configuration has been taken care of. */
        reg_write(ohci, OHCI1394_HCControlClear,
                  OHCI1394_HCControl_programPhyEnable);

        return 0;
}

static int probe_tsb41ba3d(struct fw_ohci *ohci)
{
        /* TI vendor ID = 0x080028, TSB41BA3D product ID = 0x833005 (sic) */
        static const u8 id[] = { 0x08, 0x00, 0x28, 0x83, 0x30, 0x05, };
        int reg, i;

        reg = read_phy_reg(ohci, 2);
        if (reg < 0)
                return reg;
        if ((reg & PHY_EXTENDED_REGISTERS) != PHY_EXTENDED_REGISTERS)
                return 0;

        for (i = ARRAY_SIZE(id) - 1; i >= 0; i--) {
                reg = read_paged_phy_reg(ohci, 1, i + 10);
                if (reg < 0)
                        return reg;
                if (reg != id[i])
                        return 0;
        }
        return 1;
}

static int ohci_enable(struct fw_card *card,
                       const __be32 *config_rom, size_t length)
{
        struct fw_ohci *ohci = fw_ohci(card);
        u32 lps, version, irqs;
        int i, ret;

        ret = software_reset(ohci);
        if (ret < 0) {
                ohci_err(ohci, "failed to reset ohci card\n");
                return ret;
        }

        /*
         * Now enable LPS, which we need in order to start accessing
         * most of the registers.  In fact, on some cards (ALI M5251),
         * accessing registers in the SClk domain without LPS enabled
         * will lock up the machine.  Wait 50msec to make sure we have
         * full link enabled.  However, with some cards (well, at least
         * a JMicron PCIe card), we have to try again sometimes.
         *
         * TI TSB82AA2 + TSB81BA3(A) cards signal LPS enabled early but
         * cannot actually use the phy at that time.  These need tens of
         * millisecods pause between LPS write and first phy access too.
         */

        reg_write(ohci, OHCI1394_HCControlSet,
                  OHCI1394_HCControl_LPS |
                  OHCI1394_HCControl_postedWriteEnable);
        flush_writes(ohci);

        for (lps = 0, i = 0; !lps && i < 3; i++) {
                msleep(50);
                lps = reg_read(ohci, OHCI1394_HCControlSet) &
                      OHCI1394_HCControl_LPS;
        }

        if (!lps) {
                ohci_err(ohci, "failed to set Link Power Status\n");
                return -EIO;
        }

        if (ohci->quirks & QUIRK_TI_SLLZ059) {
                ret = probe_tsb41ba3d(ohci);
                if (ret < 0)
                        return ret;
                if (ret)
                        ohci_notice(ohci, "local TSB41BA3D phy\n");
                else
                        ohci->quirks &= ~QUIRK_TI_SLLZ059;
        }

        reg_write(ohci, OHCI1394_HCControlClear,
                  OHCI1394_HCControl_noByteSwapData);

        reg_write(ohci, OHCI1394_SelfIDBuffer, ohci->self_id_bus);
        reg_write(ohci, OHCI1394_LinkControlSet,
                  OHCI1394_LinkControl_cycleTimerEnable |
                  OHCI1394_LinkControl_cycleMaster);

        reg_write(ohci, OHCI1394_ATRetries,
                  OHCI1394_MAX_AT_REQ_RETRIES |
                  (OHCI1394_MAX_AT_RESP_RETRIES << 4) |
                  (OHCI1394_MAX_PHYS_RESP_RETRIES << 8) |
                  (200 << 16));

        ohci->bus_time_running = false;

        for (i = 0; i < 32; i++)
                if (ohci->ir_context_support & (1 << i))
                        reg_write(ohci, OHCI1394_IsoRcvContextControlClear(i),
                                  IR_CONTEXT_MULTI_CHANNEL_MODE);

        version = reg_read(ohci, OHCI1394_Version) & 0x00ff00ff;
        if (version >= OHCI_VERSION_1_1) {
                reg_write(ohci, OHCI1394_InitialChannelsAvailableHi,
                          0xfffffffe);
                card->broadcast_channel_auto_allocated = true;
        }

        /* Get implemented bits of the priority arbitration request counter. */
        reg_write(ohci, OHCI1394_FairnessControl, 0x3f);
        ohci->pri_req_max = reg_read(ohci, OHCI1394_FairnessControl) & 0x3f;
        reg_write(ohci, OHCI1394_FairnessControl, 0);
        card->priority_budget_implemented = ohci->pri_req_max != 0;

        reg_write(ohci, OHCI1394_PhyUpperBound, FW_MAX_PHYSICAL_RANGE >> 16);
        reg_write(ohci, OHCI1394_IntEventClear, ~0);
        reg_write(ohci, OHCI1394_IntMaskClear, ~0);

        ret = configure_1394a_enhancements(ohci);
        if (ret < 0)
                return ret;

        /* Activate link_on bit and contender bit in our self ID packets.*/
        ret = ohci_update_phy_reg(card, 4, 0, PHY_LINK_ACTIVE | PHY_CONTENDER);
        if (ret < 0)
                return ret;

        /*
         * When the link is not yet enabled, the atomic config rom
         * update mechanism described below in ohci_set_config_rom()
         * is not active.  We have to update ConfigRomHeader and
         * BusOptions manually, and the write to ConfigROMmap takes
         * effect immediately.  We tie this to the enabling of the
         * link, so we have a valid config rom before enabling - the
         * OHCI requires that ConfigROMhdr and BusOptions have valid
         * values before enabling.
         *
         * However, when the ConfigROMmap is written, some controllers
         * always read back quadlets 0 and 2 from the config rom to
         * the ConfigRomHeader and BusOptions registers on bus reset.
         * They shouldn't do that in this initial case where the link
         * isn't enabled.  This means we have to use the same
         * workaround here, setting the bus header to 0 and then write
         * the right values in the bus reset work item.
         */

        if (config_rom) {
                ohci->next_config_rom = dmam_alloc_coherent(ohci->card.device, CONFIG_ROM_SIZE,
                                                            &ohci->next_config_rom_bus, GFP_KERNEL);
                if (ohci->next_config_rom == NULL)
                        return -ENOMEM;

                copy_config_rom(ohci->next_config_rom, config_rom, length);
        } else {
                /*
                 * In the suspend case, config_rom is NULL, which
                 * means that we just reuse the old config rom.
                 */
                ohci->next_config_rom = ohci->config_rom;
                ohci->next_config_rom_bus = ohci->config_rom_bus;
        }

        ohci->next_header = ohci->next_config_rom[0];
        ohci->next_config_rom[0] = 0;
        reg_write(ohci, OHCI1394_ConfigROMhdr, 0);
        reg_write(ohci, OHCI1394_BusOptions,
                  be32_to_cpu(ohci->next_config_rom[2]));
        reg_write(ohci, OHCI1394_ConfigROMmap, ohci->next_config_rom_bus);

        reg_write(ohci, OHCI1394_AsReqFilterHiSet, 0x80000000);

        irqs =  OHCI1394_reqTxComplete | OHCI1394_respTxComplete |
                OHCI1394_RQPkt | OHCI1394_RSPkt |
                OHCI1394_isochTx | OHCI1394_isochRx |
                OHCI1394_postedWriteErr |
                OHCI1394_selfIDComplete |
                OHCI1394_regAccessFail |
                OHCI1394_cycleInconsistent |
                OHCI1394_unrecoverableError |
                OHCI1394_cycleTooLong |
                OHCI1394_masterIntEnable |
                OHCI1394_busReset;
        reg_write(ohci, OHCI1394_IntMaskSet, irqs);

        reg_write(ohci, OHCI1394_HCControlSet,
                  OHCI1394_HCControl_linkEnable |
                  OHCI1394_HCControl_BIBimageValid);

        reg_write(ohci, OHCI1394_LinkControlSet,
                  OHCI1394_LinkControl_rcvSelfID |
                  OHCI1394_LinkControl_rcvPhyPkt);

        ar_context_run(&ohci->ar_request_ctx);
        ar_context_run(&ohci->ar_response_ctx);

        flush_writes(ohci);

        /* We are ready to go, reset bus to finish initialization. */
        fw_schedule_bus_reset(&ohci->card, false, true);

        return 0;
}

static void ohci_disable(struct fw_card *card)
{
        struct pci_dev *pdev = to_pci_dev(card->device);
        struct fw_ohci *ohci = pci_get_drvdata(pdev);
        int i, irq = pci_irq_vector(pdev, 0);

        // If the removal is happening from the suspend state, LPS won't be enabled and host
        // registers (eg., IntMaskClear) won't be accessible.
        if (!(reg_read(ohci, OHCI1394_HCControlSet) & OHCI1394_HCControl_LPS))
                return;

        reg_write(ohci, OHCI1394_IntMaskClear, ~0);
        flush_writes(ohci);

        if (irq >= 0)
                synchronize_irq(irq);

        flush_work(&ohci->ar_request_ctx.work);
        flush_work(&ohci->ar_response_ctx.work);
        flush_work(&ohci->at_request_ctx.work);
        flush_work(&ohci->at_response_ctx.work);

        for (i = 0; i < ohci->n_ir; ++i) {
                if (!(ohci->ir_context_mask & BIT(i)))
                        flush_work(&ohci->ir_context_list[i].base.work);
        }
        for (i = 0; i < ohci->n_it; ++i) {
                if (!(ohci->it_context_mask & BIT(i)))
                        flush_work(&ohci->it_context_list[i].base.work);
        }

        at_context_flush(&ohci->at_request_ctx);
        at_context_flush(&ohci->at_response_ctx);
}

static int ohci_set_config_rom(struct fw_card *card,
                               const __be32 *config_rom, size_t length)
{
        struct fw_ohci *ohci;
        __be32 *next_config_rom;
        dma_addr_t next_config_rom_bus;

        ohci = fw_ohci(card);

        /*
         * When the OHCI controller is enabled, the config rom update
         * mechanism is a bit tricky, but easy enough to use.  See
         * section 5.5.6 in the OHCI specification.
         *
         * The OHCI controller caches the new config rom address in a
         * shadow register (ConfigROMmapNext) and needs a bus reset
         * for the changes to take place.  When the bus reset is
         * detected, the controller loads the new values for the
         * ConfigRomHeader and BusOptions registers from the specified
         * config rom and loads ConfigROMmap from the ConfigROMmapNext
         * shadow register. All automatically and atomically.
         *
         * Now, there's a twist to this story.  The automatic load of
         * ConfigRomHeader and BusOptions doesn't honor the
         * noByteSwapData bit, so with a be32 config rom, the
         * controller will load be32 values in to these registers
         * during the atomic update, even on little endian
         * architectures.  The workaround we use is to put a 0 in the
         * header quadlet; 0 is endian agnostic and means that the
         * config rom isn't ready yet.  In the bus reset work item we
         * then set up the real values for the two registers.
         *
         * We use ohci->lock to avoid racing with the code that sets
         * ohci->next_config_rom to NULL (see handle_selfid_complete_event).
         */

        next_config_rom = dmam_alloc_coherent(ohci->card.device, CONFIG_ROM_SIZE,
                                              &next_config_rom_bus, GFP_KERNEL);
        if (next_config_rom == NULL)
                return -ENOMEM;

        scoped_guard(spinlock_irq, &ohci->lock) {
                // If there is not an already pending config_rom update, push our new allocation
                // into the ohci->next_config_rom and then mark the local variable as null so that
                // we won't deallocate the new buffer.
                //
                // OTOH, if there is a pending config_rom update, just use that buffer with the new
                // config_rom data, and let this routine free the unused DMA allocation.
                if (ohci->next_config_rom == NULL) {
                        ohci->next_config_rom = next_config_rom;
                        ohci->next_config_rom_bus = next_config_rom_bus;
                        next_config_rom = NULL;
                }

                copy_config_rom(ohci->next_config_rom, config_rom, length);

                ohci->next_header = config_rom[0];
                ohci->next_config_rom[0] = 0;

                reg_write(ohci, OHCI1394_ConfigROMmap, ohci->next_config_rom_bus);
        }

        /* If we didn't use the DMA allocation, delete it. */
        if (next_config_rom != NULL) {
                dmam_free_coherent(ohci->card.device, CONFIG_ROM_SIZE, next_config_rom,
                                   next_config_rom_bus);
        }

        /*
         * Now initiate a bus reset to have the changes take
         * effect. We clean up the old config rom memory and DMA
         * mappings in the bus reset work item, since the OHCI
         * controller could need to access it before the bus reset
         * takes effect.
         */

        fw_schedule_bus_reset(&ohci->card, true, true);

        return 0;
}

static void ohci_send_request(struct fw_card *card, struct fw_packet *packet)
{
        struct fw_ohci *ohci = fw_ohci(card);

        at_context_transmit(&ohci->at_request_ctx, packet);
}

static void ohci_send_response(struct fw_card *card, struct fw_packet *packet)
{
        struct fw_ohci *ohci = fw_ohci(card);

        at_context_transmit(&ohci->at_response_ctx, packet);
}

static int ohci_cancel_packet(struct fw_card *card, struct fw_packet *packet)
{
        struct fw_ohci *ohci = fw_ohci(card);
        struct at_context *ctx = &ohci->at_request_ctx;
        struct driver_data *driver_data = packet->driver_data;
        int ret = -ENOENT;

        // Avoid dead lock due to programming mistake.
        if (WARN_ON_ONCE(current_work() == &ctx->work))
                return 0;
        disable_work_sync(&ctx->work);

        if (packet->ack != 0)
                goto out;

        if (packet->payload_mapped)
                dma_unmap_single(ohci->card.device, packet->payload_bus,
                                 packet->payload_length, DMA_TO_DEVICE);

        driver_data->packet = NULL;
        packet->ack = RCODE_CANCELLED;

        // Timestamping on behalf of the hardware.
        packet->timestamp = cycle_time_to_ohci_tstamp(get_cycle_time(ohci));

        packet->callback(packet, &ohci->card, packet->ack);
        ret = 0;
 out:
        enable_work(&ctx->work);

        return ret;
}

static int ohci_enable_phys_dma(struct fw_card *card,
                                int node_id, int generation)
{
        struct fw_ohci *ohci = fw_ohci(card);
        int n, ret = 0;

        if (param_remote_dma)
                return 0;

        /*
         * FIXME:  Make sure this bitmask is cleared when we clear the busReset
         * interrupt bit.  Clear physReqResourceAllBuses on bus reset.
         */

        guard(spinlock_irqsave)(&ohci->lock);

        if (ohci->generation != generation)
                return -ESTALE;

        /*
         * Note, if the node ID contains a non-local bus ID, physical DMA is
         * enabled for _all_ nodes on remote buses.
         */

        n = (node_id & 0xffc0) == LOCAL_BUS ? node_id & 0x3f : 63;
        if (n < 32)
                reg_write(ohci, OHCI1394_PhyReqFilterLoSet, 1 << n);
        else
                reg_write(ohci, OHCI1394_PhyReqFilterHiSet, 1 << (n - 32));

        flush_writes(ohci);

        return ret;
}

static u32 ohci_read_csr(struct fw_card *card, int csr_offset)
{
        struct fw_ohci *ohci = fw_ohci(card);
        u32 value;

        switch (csr_offset) {
        case CSR_STATE_CLEAR:
        case CSR_STATE_SET:
                if (ohci->is_root &&
                    (reg_read(ohci, OHCI1394_LinkControlSet) &
                     OHCI1394_LinkControl_cycleMaster))
                        value = CSR_STATE_BIT_CMSTR;
                else
                        value = 0;
                if (ohci->csr_state_setclear_abdicate)
                        value |= CSR_STATE_BIT_ABDICATE;

                return value;

        case CSR_NODE_IDS:
                return reg_read(ohci, OHCI1394_NodeID) << 16;

        case CSR_CYCLE_TIME:
                return get_cycle_time(ohci);

        case CSR_BUS_TIME:
        {
                // We might be called just after the cycle timer has wrapped around but just before
                // the cycle64Seconds handler, so we better check here, too, if the bus time needs
                // to be updated.

                guard(spinlock_irqsave)(&ohci->lock);
                return update_bus_time(ohci);
        }
        case CSR_BUSY_TIMEOUT:
                value = reg_read(ohci, OHCI1394_ATRetries);
                return (value >> 4) & 0x0ffff00f;

        case CSR_PRIORITY_BUDGET:
                return (reg_read(ohci, OHCI1394_FairnessControl) & 0x3f) |
                        (ohci->pri_req_max << 8);

        default:
                WARN_ON(1);
                return 0;
        }
}

static void ohci_write_csr(struct fw_card *card, int csr_offset, u32 value)
{
        struct fw_ohci *ohci = fw_ohci(card);

        switch (csr_offset) {
        case CSR_STATE_CLEAR:
                if ((value & CSR_STATE_BIT_CMSTR) && ohci->is_root) {
                        reg_write(ohci, OHCI1394_LinkControlClear,
                                  OHCI1394_LinkControl_cycleMaster);
                        flush_writes(ohci);
                }
                if (value & CSR_STATE_BIT_ABDICATE)
                        ohci->csr_state_setclear_abdicate = false;
                break;

        case CSR_STATE_SET:
                if ((value & CSR_STATE_BIT_CMSTR) && ohci->is_root) {
                        reg_write(ohci, OHCI1394_LinkControlSet,
                                  OHCI1394_LinkControl_cycleMaster);
                        flush_writes(ohci);
                }
                if (value & CSR_STATE_BIT_ABDICATE)
                        ohci->csr_state_setclear_abdicate = true;
                break;

        case CSR_NODE_IDS:
                reg_write(ohci, OHCI1394_NodeID, value >> 16);
                flush_writes(ohci);
                break;

        case CSR_CYCLE_TIME:
                reg_write(ohci, OHCI1394_IsochronousCycleTimer, value);
                reg_write(ohci, OHCI1394_IntEventSet,
                          OHCI1394_cycleInconsistent);
                flush_writes(ohci);
                break;

        case CSR_BUS_TIME:
        {
                guard(spinlock_irqsave)(&ohci->lock);
                ohci->bus_time = (update_bus_time(ohci) & 0x40) | (value & ~0x7f);
                break;
        }
        case CSR_BUSY_TIMEOUT:
                value = (value & 0xf) | ((value & 0xf) << 4) |
                        ((value & 0xf) << 8) | ((value & 0x0ffff000) << 4);
                reg_write(ohci, OHCI1394_ATRetries, value);
                flush_writes(ohci);
                break;

        case CSR_PRIORITY_BUDGET:
                reg_write(ohci, OHCI1394_FairnessControl, value & 0x3f);
                flush_writes(ohci);
                break;

        default:
                WARN_ON(1);
                break;
        }
}

static void flush_iso_completions(struct iso_context *ctx, enum fw_iso_context_completions_cause cause)
{
        trace_isoc_inbound_single_completions(&ctx->base, ctx->sc.last_timestamp, cause,
                                              ctx->sc.header, ctx->sc.header_length);
        trace_isoc_outbound_completions(&ctx->base, ctx->sc.last_timestamp, cause, ctx->sc.header,
                                        ctx->sc.header_length);

        ctx->base.callback.sc(&ctx->base, ctx->sc.last_timestamp, ctx->sc.header_length,
                              ctx->sc.header, ctx->base.callback_data);
        ctx->sc.header_length = 0;
}

static void copy_iso_headers(struct iso_context *ctx, const u32 *dma_hdr)
{
        u32 *ctx_hdr;

        if (ctx->sc.header_length + ctx->base.header_size > ctx->base.header_storage_size) {
                if (ctx->base.flags & FW_ISO_CONTEXT_FLAG_DROP_OVERFLOW_HEADERS)
                        return;
                flush_iso_completions(ctx, FW_ISO_CONTEXT_COMPLETIONS_CAUSE_HEADER_OVERFLOW);
        }

        ctx_hdr = ctx->sc.header + ctx->sc.header_length;
        ctx->sc.last_timestamp = (u16)le32_to_cpu((__force __le32)dma_hdr[0]);

        /*
         * The two iso header quadlets are byteswapped to little
         * endian by the controller, but we want to present them
         * as big endian for consistency with the bus endianness.
         */
        if (ctx->base.header_size > 0)
                ctx_hdr[0] = swab32(dma_hdr[1]); /* iso packet header */
        if (ctx->base.header_size > 4)
                ctx_hdr[1] = swab32(dma_hdr[0]); /* timestamp */
        if (ctx->base.header_size > 8)
                memcpy(&ctx_hdr[2], &dma_hdr[2], ctx->base.header_size - 8);
        ctx->sc.header_length += ctx->base.header_size;
}

static int handle_ir_packet_per_buffer(struct context *context,
                                       struct descriptor *d,
                                       struct descriptor *last)
{
        struct iso_context *ctx =
                container_of(context, struct iso_context, context);
        struct descriptor *pd;
        u32 buffer_dma;

        for (pd = d; pd <= last; pd++)
                if (pd->transfer_status)
                        break;
        if (pd > last)
                /* Descriptor(s) not done yet, stop iteration */
                return 0;

        while (!(d->control & cpu_to_le16(DESCRIPTOR_BRANCH_ALWAYS))) {
                d++;
                buffer_dma = le32_to_cpu(d->data_address);
                dma_sync_single_range_for_cpu(context->ohci->card.device,
                                              buffer_dma & PAGE_MASK,
                                              buffer_dma & ~PAGE_MASK,
                                              le16_to_cpu(d->req_count),
                                              DMA_FROM_DEVICE);
        }

        copy_iso_headers(ctx, (u32 *) (last + 1));

        if (last->control & cpu_to_le16(DESCRIPTOR_IRQ_ALWAYS))
                flush_iso_completions(ctx, FW_ISO_CONTEXT_COMPLETIONS_CAUSE_INTERRUPT);

        return 1;
}

/* d == last because each descriptor block is only a single descriptor. */
static int handle_ir_buffer_fill(struct context *context,
                                 struct descriptor *d,
                                 struct descriptor *last)
{
        struct iso_context *ctx =
                container_of(context, struct iso_context, context);
        unsigned int req_count, res_count, completed;
        u32 buffer_dma;

        req_count = le16_to_cpu(last->req_count);
        res_count = le16_to_cpu(READ_ONCE(last->res_count));
        completed = req_count - res_count;
        buffer_dma = le32_to_cpu(last->data_address);

        if (completed > 0) {
                ctx->mc.buffer_bus = buffer_dma;
                ctx->mc.completed = completed;
        }

        if (res_count != 0)
                /* Descriptor(s) not done yet, stop iteration */
                return 0;

        dma_sync_single_range_for_cpu(context->ohci->card.device,
                                      buffer_dma & PAGE_MASK,
                                      buffer_dma & ~PAGE_MASK,
                                      completed, DMA_FROM_DEVICE);

        if (last->control & cpu_to_le16(DESCRIPTOR_IRQ_ALWAYS)) {
                trace_isoc_inbound_multiple_completions(&ctx->base, completed,
                                                        FW_ISO_CONTEXT_COMPLETIONS_CAUSE_INTERRUPT);

                ctx->base.callback.mc(&ctx->base,
                                      buffer_dma + completed,
                                      ctx->base.callback_data);
                ctx->mc.completed = 0;
        }

        return 1;
}

static void flush_ir_buffer_fill(struct iso_context *ctx)
{
        dma_sync_single_range_for_cpu(ctx->context.ohci->card.device,
                                      ctx->mc.buffer_bus & PAGE_MASK,
                                      ctx->mc.buffer_bus & ~PAGE_MASK,
                                      ctx->mc.completed, DMA_FROM_DEVICE);

        trace_isoc_inbound_multiple_completions(&ctx->base, ctx->mc.completed,
                                                FW_ISO_CONTEXT_COMPLETIONS_CAUSE_FLUSH);

        ctx->base.callback.mc(&ctx->base, ctx->mc.buffer_bus + ctx->mc.completed,
                              ctx->base.callback_data);
        ctx->mc.completed = 0;
}

static inline void sync_it_packet_for_cpu(struct context *context,
                                          struct descriptor *pd)
{
        __le16 control;
        u32 buffer_dma;

        /* only packets beginning with OUTPUT_MORE* have data buffers */
        if (pd->control & cpu_to_le16(DESCRIPTOR_BRANCH_ALWAYS))
                return;

        /* skip over the OUTPUT_MORE_IMMEDIATE descriptor */
        pd += 2;

        /*
         * If the packet has a header, the first OUTPUT_MORE/LAST descriptor's
         * data buffer is in the context program's coherent page and must not
         * be synced.
         */
        if ((le32_to_cpu(pd->data_address) & PAGE_MASK) ==
            (context->current_bus          & PAGE_MASK)) {
                if (pd->control & cpu_to_le16(DESCRIPTOR_BRANCH_ALWAYS))
                        return;
                pd++;
        }

        do {
                buffer_dma = le32_to_cpu(pd->data_address);
                dma_sync_single_range_for_cpu(context->ohci->card.device,
                                              buffer_dma & PAGE_MASK,
                                              buffer_dma & ~PAGE_MASK,
                                              le16_to_cpu(pd->req_count),
                                              DMA_TO_DEVICE);
                control = pd->control;
                pd++;
        } while (!(control & cpu_to_le16(DESCRIPTOR_BRANCH_ALWAYS)));
}

static int handle_it_packet(struct context *context,
                            struct descriptor *d,
                            struct descriptor *last)
{
        struct iso_context *ctx =
                container_of(context, struct iso_context, context);
        struct descriptor *pd;
        __be32 *ctx_hdr;

        for (pd = d; pd <= last; pd++)
                if (pd->transfer_status)
                        break;
        if (pd > last)
                /* Descriptor(s) not done yet, stop iteration */
                return 0;

        sync_it_packet_for_cpu(context, d);

        if (ctx->sc.header_length + 4 > ctx->base.header_storage_size) {
                if (ctx->base.flags & FW_ISO_CONTEXT_FLAG_DROP_OVERFLOW_HEADERS)
                        return 1;
                flush_iso_completions(ctx, FW_ISO_CONTEXT_COMPLETIONS_CAUSE_HEADER_OVERFLOW);
        }

        ctx_hdr = ctx->sc.header + ctx->sc.header_length;
        ctx->sc.last_timestamp = le16_to_cpu(last->res_count);
        /* Present this value as big-endian to match the receive code */
        *ctx_hdr = cpu_to_be32((le16_to_cpu(pd->transfer_status) << 16) |
                               le16_to_cpu(pd->res_count));
        ctx->sc.header_length += 4;

        if (last->control & cpu_to_le16(DESCRIPTOR_IRQ_ALWAYS))
                flush_iso_completions(ctx, FW_ISO_CONTEXT_COMPLETIONS_CAUSE_INTERRUPT);

        return 1;
}

static void set_multichannel_mask(struct fw_ohci *ohci, u64 channels)
{
        u32 hi = channels >> 32, lo = channels;

        reg_write(ohci, OHCI1394_IRMultiChanMaskHiClear, ~hi);
        reg_write(ohci, OHCI1394_IRMultiChanMaskLoClear, ~lo);
        reg_write(ohci, OHCI1394_IRMultiChanMaskHiSet, hi);
        reg_write(ohci, OHCI1394_IRMultiChanMaskLoSet, lo);
        ohci->mc_channels = channels;
}

static struct fw_iso_context *ohci_allocate_iso_context(struct fw_card *card, int type, int channel,
                size_t header_size, size_t header_storage_size)
{
        struct fw_ohci *ohci = fw_ohci(card);
        void *header __free(kvfree) = NULL;
        struct iso_context *ctx;
        descriptor_callback_t callback;
        u64 *channels;
        u32 *mask, regs;
        int index, ret = -EBUSY;

        scoped_guard(spinlock_irq, &ohci->lock) {
                switch (type) {
                case FW_ISO_CONTEXT_TRANSMIT:
                        mask     = &ohci->it_context_mask;
                        callback = handle_it_packet;
                        index    = ffs(*mask) - 1;
                        if (index >= 0) {
                                *mask &= ~(1 << index);
                                regs = OHCI1394_IsoXmitContextBase(index);
                                ctx  = &ohci->it_context_list[index];
                        }
                        break;

                case FW_ISO_CONTEXT_RECEIVE:
                        channels = &ohci->ir_context_channels;
                        mask     = &ohci->ir_context_mask;
                        callback = handle_ir_packet_per_buffer;
                        index    = *channels & 1ULL << channel ? ffs(*mask) - 1 : -1;
                        if (index >= 0) {
                                *channels &= ~(1ULL << channel);
                                *mask     &= ~(1 << index);
                                regs = OHCI1394_IsoRcvContextBase(index);
                                ctx  = &ohci->ir_context_list[index];
                        }
                        break;

                case FW_ISO_CONTEXT_RECEIVE_MULTICHANNEL:
                        mask     = &ohci->ir_context_mask;
                        callback = handle_ir_buffer_fill;
                        index    = !ohci->mc_allocated ? ffs(*mask) - 1 : -1;
                        if (index >= 0) {
                                ohci->mc_allocated = true;
                                *mask &= ~(1 << index);
                                regs = OHCI1394_IsoRcvContextBase(index);
                                ctx  = &ohci->ir_context_list[index];
                        }
                        break;

                default:
                        index = -1;
                        ret = -ENOSYS;
                }

                if (index < 0)
                        return ERR_PTR(ret);
        }

        memset(ctx, 0, sizeof(*ctx));

        if (type != FW_ISO_CONTEXT_RECEIVE_MULTICHANNEL) {
                ctx->sc.header_length = 0;
                header = kvmalloc(header_storage_size, GFP_KERNEL);
                if (!header) {
                        ret = -ENOMEM;
                        goto out;
                }
        }

        ret = context_init(&ctx->context, ohci, regs, callback);
        if (ret < 0)
                goto out;
        fw_iso_context_init_work(&ctx->base, ohci_isoc_context_work);

        if (type != FW_ISO_CONTEXT_RECEIVE_MULTICHANNEL) {
                ctx->sc.header = no_free_ptr(header);
        } else {
                set_multichannel_mask(ohci, 0);
                ctx->mc.completed = 0;
        }

        return &ctx->base;
 out:
        scoped_guard(spinlock_irq, &ohci->lock) {
                switch (type) {
                case FW_ISO_CONTEXT_RECEIVE:
                        *channels |= 1ULL << channel;
                        break;

                case FW_ISO_CONTEXT_RECEIVE_MULTICHANNEL:
                        ohci->mc_allocated = false;
                        break;
                }
                *mask |= 1 << index;
        }

        return ERR_PTR(ret);
}

static int ohci_start_iso(struct fw_iso_context *base,
                          s32 cycle, u32 sync, u32 tags)
{
        struct iso_context *ctx = container_of(base, struct iso_context, base);
        struct fw_ohci *ohci = ctx->context.ohci;
        u32 control = IR_CONTEXT_ISOCH_HEADER, match;
        int index;

        /* the controller cannot start without any queued packets */
        if (ctx->context.last->branch_address == 0)
                return -ENODATA;

        switch (ctx->base.type) {
        case FW_ISO_CONTEXT_TRANSMIT:
                index = ctx - ohci->it_context_list;
                match = 0;
                if (cycle >= 0)
                        match = IT_CONTEXT_CYCLE_MATCH_ENABLE |
                                (cycle & 0x7fff) << 16;

                reg_write(ohci, OHCI1394_IsoXmitIntEventClear, 1 << index);
                reg_write(ohci, OHCI1394_IsoXmitIntMaskSet, 1 << index);
                context_run(&ctx->context, match);
                break;

        case FW_ISO_CONTEXT_RECEIVE_MULTICHANNEL:
                control |= IR_CONTEXT_BUFFER_FILL|IR_CONTEXT_MULTI_CHANNEL_MODE;
                fallthrough;
        case FW_ISO_CONTEXT_RECEIVE:
                index = ctx - ohci->ir_context_list;
                match = (tags << 28) | (sync << 8) | ctx->base.channel;
                if (cycle >= 0) {
                        match |= (cycle & 0x07fff) << 12;
                        control |= IR_CONTEXT_CYCLE_MATCH_ENABLE;
                }

                reg_write(ohci, OHCI1394_IsoRecvIntEventClear, 1 << index);
                reg_write(ohci, OHCI1394_IsoRecvIntMaskSet, 1 << index);
                reg_write(ohci, CONTEXT_MATCH(ctx->context.regs), match);
                context_run(&ctx->context, control);

                ctx->sync = sync;
                ctx->tags = tags;

                break;
        }

        return 0;
}

static int ohci_stop_iso(struct fw_iso_context *base)
{
        struct fw_ohci *ohci = fw_ohci(base->card);
        struct iso_context *ctx = container_of(base, struct iso_context, base);
        int index;

        switch (ctx->base.type) {
        case FW_ISO_CONTEXT_TRANSMIT:
                index = ctx - ohci->it_context_list;
                reg_write(ohci, OHCI1394_IsoXmitIntMaskClear, 1 << index);
                break;

        case FW_ISO_CONTEXT_RECEIVE:
        case FW_ISO_CONTEXT_RECEIVE_MULTICHANNEL:
                index = ctx - ohci->ir_context_list;
                reg_write(ohci, OHCI1394_IsoRecvIntMaskClear, 1 << index);
                break;
        }
        flush_writes(ohci);
        context_stop(&ctx->context);

        return 0;
}

static void ohci_free_iso_context(struct fw_iso_context *base)
{
        struct fw_ohci *ohci = fw_ohci(base->card);
        struct iso_context *ctx = container_of(base, struct iso_context, base);
        int index;

        ohci_stop_iso(base);
        context_release(&ctx->context);

        if (base->type != FW_ISO_CONTEXT_RECEIVE_MULTICHANNEL) {
                kvfree(ctx->sc.header);
                ctx->sc.header = NULL;
        }

        guard(spinlock_irqsave)(&ohci->lock);

        switch (base->type) {
        case FW_ISO_CONTEXT_TRANSMIT:
                index = ctx - ohci->it_context_list;
                ohci->it_context_mask |= 1 << index;
                break;

        case FW_ISO_CONTEXT_RECEIVE:
                index = ctx - ohci->ir_context_list;
                ohci->ir_context_mask |= 1 << index;
                ohci->ir_context_channels |= 1ULL << base->channel;
                break;

        case FW_ISO_CONTEXT_RECEIVE_MULTICHANNEL:
                index = ctx - ohci->ir_context_list;
                ohci->ir_context_mask |= 1 << index;
                ohci->ir_context_channels |= ohci->mc_channels;
                ohci->mc_channels = 0;
                ohci->mc_allocated = false;
                break;
        }
}

static int ohci_set_iso_channels(struct fw_iso_context *base, u64 *channels)
{
        struct fw_ohci *ohci = fw_ohci(base->card);

        switch (base->type) {
        case FW_ISO_CONTEXT_RECEIVE_MULTICHANNEL:
        {
                guard(spinlock_irqsave)(&ohci->lock);

                // Don't allow multichannel to grab other contexts' channels.
                if (~ohci->ir_context_channels & ~ohci->mc_channels & *channels) {
                        *channels = ohci->ir_context_channels;
                        return -EBUSY;
                } else {
                        set_multichannel_mask(ohci, *channels);
                        return 0;
                }
        }
        default:
                return -EINVAL;
        }
}

static void __maybe_unused ohci_resume_iso_dma(struct fw_ohci *ohci)
{
        int i;
        struct iso_context *ctx;

        for (i = 0 ; i < ohci->n_ir ; i++) {
                ctx = &ohci->ir_context_list[i];
                if (ctx->context.running)
                        ohci_start_iso(&ctx->base, 0, ctx->sync, ctx->tags);
        }

        for (i = 0 ; i < ohci->n_it ; i++) {
                ctx = &ohci->it_context_list[i];
                if (ctx->context.running)
                        ohci_start_iso(&ctx->base, 0, ctx->sync, ctx->tags);
        }
}

static int queue_iso_transmit(struct iso_context *ctx,
                              struct fw_iso_packet *packet,
                              struct fw_iso_buffer *buffer,
                              unsigned long payload)
{
        struct descriptor *d, *last, *pd;
        struct fw_iso_packet *p;
        __le32 *header;
        dma_addr_t d_bus;
        u32 z, header_z, payload_z, irq;
        u32 payload_index, payload_end_index, next_page_index;
        int page, end_page, i, length, offset;

        p = packet;
        payload_index = payload;

        if (p->skip)
                z = 1;
        else
                z = 2;
        if (p->header_length > 0)
                z++;

        /* Determine the first page the payload isn't contained in. */
        end_page = PAGE_ALIGN(payload_index + p->payload_length) >> PAGE_SHIFT;
        if (p->payload_length > 0)
                payload_z = end_page - (payload_index >> PAGE_SHIFT);
        else
                payload_z = 0;

        z += payload_z;

        /* Get header size in number of descriptors. */
        header_z = DIV_ROUND_UP(p->header_length, sizeof(*d));

        d = context_get_descriptors(&ctx->context, z + header_z, &d_bus);
        if (d == NULL)
                return -ENOMEM;

        if (!p->skip) {
                d[0].control   = cpu_to_le16(DESCRIPTOR_KEY_IMMEDIATE);
                d[0].req_count = cpu_to_le16(8);
                /*
                 * Link the skip address to this descriptor itself.  This causes
                 * a context to skip a cycle whenever lost cycles or FIFO
                 * overruns occur, without dropping the data.  The application
                 * should then decide whether this is an error condition or not.
                 * FIXME:  Make the context's cycle-lost behaviour configurable?
                 */
                d[0].branch_address = cpu_to_le32(d_bus | z);

                header = (__le32 *) &d[1];

                ohci1394_it_data_set_speed(header, ctx->base.speed);
                ohci1394_it_data_set_tag(header, p->tag);
                ohci1394_it_data_set_channel(header, ctx->base.channel);
                ohci1394_it_data_set_tcode(header, TCODE_STREAM_DATA);
                ohci1394_it_data_set_sync(header, p->sy);

                ohci1394_it_data_set_data_length(header, p->header_length + p->payload_length);
        }

        if (p->header_length > 0) {
                d[2].req_count    = cpu_to_le16(p->header_length);
                d[2].data_address = cpu_to_le32(d_bus + z * sizeof(*d));
                memcpy(&d[z], p->header, p->header_length);
        }

        pd = d + z - payload_z;
        payload_end_index = payload_index + p->payload_length;
        for (i = 0; i < payload_z; i++) {
                page               = payload_index >> PAGE_SHIFT;
                offset             = payload_index & ~PAGE_MASK;
                next_page_index    = (page + 1) << PAGE_SHIFT;
                length             =
                        min(next_page_index, payload_end_index) - payload_index;
                pd[i].req_count    = cpu_to_le16(length);

                dma_addr_t dma_addr = buffer->dma_addrs[page];
                pd[i].data_address = cpu_to_le32(dma_addr + offset);

                dma_sync_single_range_for_device(ctx->context.ohci->card.device,
                                                 dma_addr, offset, length,
                                                 DMA_TO_DEVICE);

                payload_index += length;
        }

        if (p->interrupt)
                irq = DESCRIPTOR_IRQ_ALWAYS;
        else
                irq = DESCRIPTOR_NO_IRQ;

        last = z == 2 ? d : d + z - 1;
        last->control |= cpu_to_le16(DESCRIPTOR_OUTPUT_LAST |
                                     DESCRIPTOR_STATUS |
                                     DESCRIPTOR_BRANCH_ALWAYS |
                                     irq);

        context_append(&ctx->context, d, z, header_z);

        return 0;
}

static int queue_iso_packet_per_buffer(struct iso_context *ctx,
                                       struct fw_iso_packet *packet,
                                       struct fw_iso_buffer *buffer,
                                       unsigned long payload)
{
        struct device *device = ctx->context.ohci->card.device;
        struct descriptor *d, *pd;
        dma_addr_t d_bus;
        u32 z, header_z, rest;
        int i, j, length;
        int page, offset, packet_count, header_size, payload_per_buffer;

        /*
         * The OHCI controller puts the isochronous header and trailer in the
         * buffer, so we need at least 8 bytes.
         */
        packet_count = packet->header_length / ctx->base.header_size;
        header_size  = max(ctx->base.header_size, (size_t)8);

        /* Get header size in number of descriptors. */
        header_z = DIV_ROUND_UP(header_size, sizeof(*d));
        page     = payload >> PAGE_SHIFT;
        offset   = payload & ~PAGE_MASK;
        payload_per_buffer = packet->payload_length / packet_count;

        for (i = 0; i < packet_count; i++) {
                /* d points to the header descriptor */
                z = DIV_ROUND_UP(payload_per_buffer + offset, PAGE_SIZE) + 1;
                d = context_get_descriptors(&ctx->context,
                                z + header_z, &d_bus);
                if (d == NULL)
                        return -ENOMEM;

                d->control      = cpu_to_le16(DESCRIPTOR_STATUS |
                                              DESCRIPTOR_INPUT_MORE);
                if (packet->skip && i == 0)
                        d->control |= cpu_to_le16(DESCRIPTOR_WAIT);
                d->req_count    = cpu_to_le16(header_size);
                d->res_count    = d->req_count;
                d->transfer_status = 0;
                d->data_address = cpu_to_le32(d_bus + (z * sizeof(*d)));

                rest = payload_per_buffer;
                pd = d;
                for (j = 1; j < z; j++) {
                        pd++;
                        pd->control = cpu_to_le16(DESCRIPTOR_STATUS |
                                                  DESCRIPTOR_INPUT_MORE);

                        if (offset + rest < PAGE_SIZE)
                                length = rest;
                        else
                                length = PAGE_SIZE - offset;
                        pd->req_count = cpu_to_le16(length);
                        pd->res_count = pd->req_count;
                        pd->transfer_status = 0;

                        dma_addr_t dma_addr = buffer->dma_addrs[page];
                        pd->data_address = cpu_to_le32(dma_addr + offset);

                        dma_sync_single_range_for_device(device, dma_addr,
                                                         offset, length,
                                                         DMA_FROM_DEVICE);

                        offset = (offset + length) & ~PAGE_MASK;
                        rest -= length;
                        if (offset == 0)
                                page++;
                }
                pd->control = cpu_to_le16(DESCRIPTOR_STATUS |
                                          DESCRIPTOR_INPUT_LAST |
                                          DESCRIPTOR_BRANCH_ALWAYS);
                if (packet->interrupt && i == packet_count - 1)
                        pd->control |= cpu_to_le16(DESCRIPTOR_IRQ_ALWAYS);

                context_append(&ctx->context, d, z, header_z);
        }

        return 0;
}

static int queue_iso_buffer_fill(struct iso_context *ctx,
                                 struct fw_iso_packet *packet,
                                 struct fw_iso_buffer *buffer,
                                 unsigned long payload)
{
        struct descriptor *d;
        dma_addr_t d_bus;
        int page, offset, rest, z, i, length;

        page   = payload >> PAGE_SHIFT;
        offset = payload & ~PAGE_MASK;
        rest   = packet->payload_length;

        /* We need one descriptor for each page in the buffer. */
        z = DIV_ROUND_UP(offset + rest, PAGE_SIZE);

        if (WARN_ON(offset & 3 || rest & 3 || page + z > buffer->page_count))
                return -EFAULT;

        for (i = 0; i < z; i++) {
                d = context_get_descriptors(&ctx->context, 1, &d_bus);
                if (d == NULL)
                        return -ENOMEM;

                d->control = cpu_to_le16(DESCRIPTOR_INPUT_MORE |
                                         DESCRIPTOR_BRANCH_ALWAYS);
                if (packet->skip && i == 0)
                        d->control |= cpu_to_le16(DESCRIPTOR_WAIT);
                if (packet->interrupt && i == z - 1)
                        d->control |= cpu_to_le16(DESCRIPTOR_IRQ_ALWAYS);

                if (offset + rest < PAGE_SIZE)
                        length = rest;
                else
                        length = PAGE_SIZE - offset;
                d->req_count = cpu_to_le16(length);
                d->res_count = d->req_count;
                d->transfer_status = 0;

                dma_addr_t dma_addr = buffer->dma_addrs[page];
                d->data_address = cpu_to_le32(dma_addr + offset);

                dma_sync_single_range_for_device(ctx->context.ohci->card.device,
                                                 dma_addr, offset, length,
                                                 DMA_FROM_DEVICE);

                rest -= length;
                offset = 0;
                page++;

                context_append(&ctx->context, d, 1, 0);
        }

        return 0;
}

static int ohci_queue_iso(struct fw_iso_context *base,
                          struct fw_iso_packet *packet,
                          struct fw_iso_buffer *buffer,
                          unsigned long payload)
{
        struct iso_context *ctx = container_of(base, struct iso_context, base);

        guard(spinlock_irqsave)(&ctx->context.ohci->lock);

        switch (base->type) {
        case FW_ISO_CONTEXT_TRANSMIT:
                return queue_iso_transmit(ctx, packet, buffer, payload);
        case FW_ISO_CONTEXT_RECEIVE:
                return queue_iso_packet_per_buffer(ctx, packet, buffer, payload);
        case FW_ISO_CONTEXT_RECEIVE_MULTICHANNEL:
                return queue_iso_buffer_fill(ctx, packet, buffer, payload);
        default:
                return -ENOSYS;
        }
}

static void ohci_flush_queue_iso(struct fw_iso_context *base)
{
        struct context *ctx =
                        &container_of(base, struct iso_context, base)->context;

        reg_write(ctx->ohci, CONTROL_SET(ctx->regs), CONTEXT_WAKE);
}

static int ohci_flush_iso_completions(struct fw_iso_context *base)
{
        struct iso_context *ctx = container_of(base, struct iso_context, base);
        int ret = 0;

        if (!test_and_set_bit_lock(0, &ctx->flushing_completions)) {
                ohci_isoc_context_work(&base->work);

                switch (base->type) {
                case FW_ISO_CONTEXT_TRANSMIT:
                case FW_ISO_CONTEXT_RECEIVE:
                        if (ctx->sc.header_length != 0)
                                flush_iso_completions(ctx, FW_ISO_CONTEXT_COMPLETIONS_CAUSE_FLUSH);
                        break;
                case FW_ISO_CONTEXT_RECEIVE_MULTICHANNEL:
                        if (ctx->mc.completed != 0)
                                flush_ir_buffer_fill(ctx);
                        break;
                default:
                        ret = -ENOSYS;
                }

                clear_bit_unlock(0, &ctx->flushing_completions);
                smp_mb__after_atomic();
        }

        return ret;
}

static const struct fw_card_driver ohci_driver = {
        .enable                 = ohci_enable,
        .disable                = ohci_disable,
        .read_phy_reg           = ohci_read_phy_reg,
        .update_phy_reg         = ohci_update_phy_reg,
        .set_config_rom         = ohci_set_config_rom,
        .send_request           = ohci_send_request,
        .send_response          = ohci_send_response,
        .cancel_packet          = ohci_cancel_packet,
        .enable_phys_dma        = ohci_enable_phys_dma,
        .read_csr               = ohci_read_csr,
        .write_csr              = ohci_write_csr,

        .allocate_iso_context   = ohci_allocate_iso_context,
        .free_iso_context       = ohci_free_iso_context,
        .set_iso_channels       = ohci_set_iso_channels,
        .queue_iso              = ohci_queue_iso,
        .flush_queue_iso        = ohci_flush_queue_iso,
        .flush_iso_completions  = ohci_flush_iso_completions,
        .start_iso              = ohci_start_iso,
        .stop_iso               = ohci_stop_iso,
};

#ifdef CONFIG_PPC_PMAC
static void pmac_ohci_on(struct pci_dev *dev)
{
        if (machine_is(powermac)) {
                struct device_node *ofn = pci_device_to_OF_node(dev);

                if (ofn) {
                        pmac_call_feature(PMAC_FTR_1394_CABLE_POWER, ofn, 0, 1);
                        pmac_call_feature(PMAC_FTR_1394_ENABLE, ofn, 0, 1);
                }
        }
}

static void pmac_ohci_off(struct pci_dev *dev)
{
        if (machine_is(powermac)) {
                struct device_node *ofn = pci_device_to_OF_node(dev);

                if (ofn) {
                        pmac_call_feature(PMAC_FTR_1394_ENABLE, ofn, 0, 0);
                        pmac_call_feature(PMAC_FTR_1394_CABLE_POWER, ofn, 0, 0);
                }
        }
}
#else
static inline void pmac_ohci_on(struct pci_dev *dev) {}
static inline void pmac_ohci_off(struct pci_dev *dev) {}
#endif /* CONFIG_PPC_PMAC */

static void release_ohci(struct device *dev, void *data)
{
        struct pci_dev *pdev = to_pci_dev(dev);
        struct fw_ohci *ohci = pci_get_drvdata(pdev);

        pmac_ohci_off(pdev);

        ar_context_release(&ohci->ar_response_ctx);
        ar_context_release(&ohci->ar_request_ctx);

        dev_notice(dev, "removed fw-ohci device\n");
}

static int pci_probe(struct pci_dev *dev,
                               const struct pci_device_id *ent)
{
        struct fw_ohci *ohci;
        u32 bus_options, max_receive, link_speed, version;
        u64 guid;
        int i, flags, irq, err;

        if (dev->vendor == PCI_VENDOR_ID_PINNACLE_SYSTEMS) {
                dev_err(&dev->dev, "Pinnacle MovieBoard is not yet supported\n");
                return -ENOSYS;
        }

        ohci = devres_alloc(release_ohci, sizeof(*ohci), GFP_KERNEL);
        if (ohci == NULL)
                return -ENOMEM;
        fw_card_initialize(&ohci->card, &ohci_driver, &dev->dev);
        pci_set_drvdata(dev, ohci);
        pmac_ohci_on(dev);
        devres_add(&dev->dev, ohci);

        err = pcim_enable_device(dev);
        if (err) {
                dev_err(&dev->dev, "failed to enable OHCI hardware\n");
                return err;
        }

        pci_set_master(dev);
        pci_write_config_dword(dev, OHCI1394_PCI_HCI_Control, 0);

        spin_lock_init(&ohci->lock);
        mutex_init(&ohci->phy_reg_mutex);

        if (!(pci_resource_flags(dev, 0) & IORESOURCE_MEM) ||
            pci_resource_len(dev, 0) < OHCI1394_REGISTER_SIZE) {
                ohci_err(ohci, "invalid MMIO resource\n");
                return -ENXIO;
        }

        ohci->registers = pcim_iomap_region(dev, 0, ohci_driver_name);
        if (IS_ERR(ohci->registers)) {
                ohci_err(ohci, "request and map MMIO resource unavailable\n");
                return -ENXIO;
        }

        for (i = 0; i < ARRAY_SIZE(ohci_quirks); i++)
                if ((ohci_quirks[i].vendor == dev->vendor) &&
                    (ohci_quirks[i].device == (unsigned short)PCI_ANY_ID ||
                     ohci_quirks[i].device == dev->device) &&
                    (ohci_quirks[i].revision == (unsigned short)PCI_ANY_ID ||
                     ohci_quirks[i].revision >= dev->revision)) {
                        ohci->quirks = ohci_quirks[i].flags;
                        break;
                }
        if (param_quirks)
                ohci->quirks = param_quirks;

        if (detect_vt630x_with_asm1083_on_amd_ryzen_machine(dev))
                ohci->quirks |= QUIRK_REBOOT_BY_CYCLE_TIMER_READ;

        /*
         * Because dma_alloc_coherent() allocates at least one page,
         * we save space by using a common buffer for the AR request/
         * response descriptors and the self IDs buffer.
         */
        BUILD_BUG_ON(AR_BUFFERS * sizeof(struct descriptor) > PAGE_SIZE/4);
        BUILD_BUG_ON(SELF_ID_BUF_SIZE > PAGE_SIZE/2);
        ohci->misc_buffer = dmam_alloc_coherent(&dev->dev, PAGE_SIZE, &ohci->misc_buffer_bus,
                                                GFP_KERNEL);
        if (!ohci->misc_buffer)
                return -ENOMEM;

        err = ar_context_init(&ohci->ar_request_ctx, ohci, 0,
                              OHCI1394_AsReqRcvContextControlSet);
        if (err < 0)
                return err;

        err = ar_context_init(&ohci->ar_response_ctx, ohci, PAGE_SIZE/4,
                              OHCI1394_AsRspRcvContextControlSet);
        if (err < 0)
                return err;

        err = context_init(&ohci->at_request_ctx.context, ohci,
                           OHCI1394_AsReqTrContextControlSet, handle_at_packet);
        if (err < 0)
                return err;
        INIT_WORK(&ohci->at_request_ctx.work, ohci_at_context_work);

        err = context_init(&ohci->at_response_ctx.context, ohci,
                           OHCI1394_AsRspTrContextControlSet, handle_at_packet);
        if (err < 0)
                return err;
        INIT_WORK(&ohci->at_response_ctx.work, ohci_at_context_work);

        reg_write(ohci, OHCI1394_IsoRecvIntMaskSet, ~0);
        ohci->ir_context_channels = ~0ULL;
        ohci->ir_context_support = reg_read(ohci, OHCI1394_IsoRecvIntMaskSet);
        reg_write(ohci, OHCI1394_IsoRecvIntMaskClear, ~0);
        ohci->ir_context_mask = ohci->ir_context_support;
        ohci->n_ir = hweight32(ohci->ir_context_mask);
        ohci->ir_context_list = devm_kcalloc(&dev->dev, ohci->n_ir, sizeof(struct iso_context), GFP_KERNEL);
        if (!ohci->ir_context_list)
                return -ENOMEM;

        reg_write(ohci, OHCI1394_IsoXmitIntMaskSet, ~0);
        ohci->it_context_support = reg_read(ohci, OHCI1394_IsoXmitIntMaskSet);
        /* JMicron JMB38x often shows 0 at first read, just ignore it */
        if (!ohci->it_context_support) {
                ohci_notice(ohci, "overriding IsoXmitIntMask\n");
                ohci->it_context_support = 0xf;
        }
        reg_write(ohci, OHCI1394_IsoXmitIntMaskClear, ~0);
        ohci->it_context_mask = ohci->it_context_support;
        ohci->n_it = hweight32(ohci->it_context_mask);
        ohci->it_context_list = devm_kcalloc(&dev->dev, ohci->n_it, sizeof(struct iso_context), GFP_KERNEL);
        if (!ohci->it_context_list)
                return -ENOMEM;

        ohci->self_id     = ohci->misc_buffer     + PAGE_SIZE/2;
        ohci->self_id_bus = ohci->misc_buffer_bus + PAGE_SIZE/2;

        bus_options = reg_read(ohci, OHCI1394_BusOptions);
        max_receive = (bus_options >> 12) & 0xf;
        link_speed = bus_options & 0x7;
        guid = ((u64) reg_read(ohci, OHCI1394_GUIDHi) << 32) |
                reg_read(ohci, OHCI1394_GUIDLo);

        flags = PCI_IRQ_INTX;
        if (!(ohci->quirks & QUIRK_NO_MSI))
                flags |= PCI_IRQ_MSI;
        err = pci_alloc_irq_vectors(dev, 1, 1, flags);
        if (err < 0)
                return err;
        irq = pci_irq_vector(dev, 0);
        if (irq < 0) {
                err = irq;
                goto fail_msi;
        }

        // IRQF_ONESHOT is not applied so that any events are handled in the hardIRQ handler during
        // invoking the threaded IRQ handler for SelfIDComplete event.
        err = request_threaded_irq(irq, irq_handler, handle_selfid_complete_event,
                                   pci_dev_msi_enabled(dev) ? 0 : IRQF_SHARED, ohci_driver_name,
                                   ohci);
        if (err < 0) {
                ohci_err(ohci, "failed to allocate interrupt %d\n", irq);
                goto fail_msi;
        }

        err = fw_card_add(&ohci->card, max_receive, link_speed, guid, ohci->n_it + ohci->n_ir);
        if (err)
                goto fail_irq;

        version = reg_read(ohci, OHCI1394_Version) & 0x00ff00ff;
        ohci_notice(ohci,
                    "added OHCI v%x.%x device as card %d, "
                    "%d IR + %d IT contexts, quirks 0x%x%s\n",
                    version >> 16, version & 0xff, ohci->card.index,
                    ohci->n_ir, ohci->n_it, ohci->quirks,
                    reg_read(ohci, OHCI1394_PhyUpperBound) ?
                        ", physUB" : "");

        return 0;

 fail_irq:
        free_irq(irq, ohci);
 fail_msi:
        pci_free_irq_vectors(dev);

        return err;
}

static void pci_remove(struct pci_dev *dev)
{
        struct fw_ohci *ohci = pci_get_drvdata(dev);
        int irq;

        fw_core_remove_card(&ohci->card);

        software_reset(ohci);

        irq = pci_irq_vector(dev, 0);
        if (irq >= 0)
                free_irq(irq, ohci);
        pci_free_irq_vectors(dev);

        dev_notice(&dev->dev, "removing fw-ohci device\n");
}

static int __maybe_unused pci_suspend(struct device *dev)
{
        struct pci_dev *pdev = to_pci_dev(dev);
        struct fw_ohci *ohci = pci_get_drvdata(pdev);

        software_reset(ohci);
        pmac_ohci_off(pdev);

        return 0;
}


static int __maybe_unused pci_resume(struct device *dev)
{
        struct pci_dev *pdev = to_pci_dev(dev);
        struct fw_ohci *ohci = pci_get_drvdata(pdev);
        int err;

        pmac_ohci_on(pdev);

        /* Some systems don't setup GUID register on resume from ram  */
        if (!reg_read(ohci, OHCI1394_GUIDLo) &&
                                        !reg_read(ohci, OHCI1394_GUIDHi)) {
                reg_write(ohci, OHCI1394_GUIDLo, (u32)ohci->card.guid);
                reg_write(ohci, OHCI1394_GUIDHi, (u32)(ohci->card.guid >> 32));
        }

        err = ohci_enable(&ohci->card, NULL, 0);
        if (err)
                return err;

        ohci_resume_iso_dma(ohci);

        return 0;
}

static const struct pci_device_id pci_table[] = {
        { PCI_DEVICE_CLASS(PCI_CLASS_SERIAL_FIREWIRE_OHCI, ~0) },
        { }
};

MODULE_DEVICE_TABLE(pci, pci_table);

static SIMPLE_DEV_PM_OPS(pci_pm_ops, pci_suspend, pci_resume);

static struct pci_driver fw_ohci_pci_driver = {
        .name           = ohci_driver_name,
        .id_table       = pci_table,
        .probe          = pci_probe,
        .remove         = pci_remove,
        .driver.pm      = &pci_pm_ops,
};

static int __init fw_ohci_init(void)
{
        return pci_register_driver(&fw_ohci_pci_driver);
}

static void __exit fw_ohci_cleanup(void)
{
        pci_unregister_driver(&fw_ohci_pci_driver);
}

module_init(fw_ohci_init);
module_exit(fw_ohci_cleanup);

MODULE_AUTHOR("Kristian Hoegsberg <krh@bitplanet.net>");
MODULE_DESCRIPTION("Driver for PCI OHCI IEEE1394 controllers");
MODULE_LICENSE("GPL");

/* Provide a module alias so root-on-sbp2 initrds don't break. */
MODULE_ALIAS("ohci1394");