// SPDX-License-Identifier: GPL-2.0
/*
 * Endpoint Function Driver to implement Non-Transparent Bridge functionality
 * Between PCI RC and EP
 *
 * Copyright (C) 2020 Texas Instruments
 * Copyright (C) 2022 NXP
 *
 * Based on pci-epf-ntb.c
 * Author: Frank Li <Frank.Li@nxp.com>
 * Author: Kishon Vijay Abraham I <kishon@ti.com>
 */

/*
 * +------------+         +---------------------------------------+
 * |            |         |                                       |
 * +------------+         |                        +--------------+
 * | NTB        |         |                        | NTB          |
 * | NetDev     |         |                        | NetDev       |
 * +------------+         |                        +--------------+
 * | NTB        |         |                        | NTB          |
 * | Transfer   |         |                        | Transfer     |
 * +------------+         |                        +--------------+
 * |            |         |                        |              |
 * |  PCI NTB   |         |                        |              |
 * |    EPF     |         |                        |              |
 * |   Driver   |         |                        | PCI Virtual  |
 * |            |         +---------------+        | NTB Driver   |
 * |            |         | PCI EP NTB    |<------>|              |
 * |            |         |  FN Driver    |        |              |
 * +------------+         +---------------+        +--------------+
 * |            |         |               |        |              |
 * |  PCI Bus   | <-----> |  PCI EP Bus   |        |  Virtual PCI |
 * |            |  PCI    |               |        |     Bus      |
 * +------------+         +---------------+--------+--------------+
 * PCIe Root Port                        PCI EP
 */

#include <linux/atomic.h>
#include <linux/delay.h>
#include <linux/io.h>
#include <linux/module.h>
#include <linux/slab.h>

#include <linux/pci-ep-msi.h>
#include <linux/pci-epc.h>
#include <linux/pci-epf.h>
#include <linux/ntb.h>

static struct workqueue_struct *kpcintb_workqueue;

#define COMMAND_CONFIGURE_DOORBELL      1
#define COMMAND_TEARDOWN_DOORBELL       2
#define COMMAND_CONFIGURE_MW            3
#define COMMAND_TEARDOWN_MW             4
#define COMMAND_LINK_UP                 5
#define COMMAND_LINK_DOWN               6

#define COMMAND_STATUS_OK               1
#define COMMAND_STATUS_ERROR            2

#define LINK_STATUS_UP                  BIT(0)

#define SPAD_COUNT                      64
#define DB_COUNT                        4
#define NTB_MW_OFFSET                   2
#define DB_COUNT_MASK                   GENMASK(15, 0)
#define MSIX_ENABLE                     BIT(16)
#define MAX_DB_COUNT                    32
#define MAX_MW                          4

enum epf_ntb_bar {
        BAR_CONFIG,
        BAR_DB,
        BAR_MW1,
        BAR_MW2,
        BAR_MW3,
        BAR_MW4,
        VNTB_BAR_NUM,
};

/*
 * +--------------------------------------------------+ Base
 * |                                                  |
 * |                                                  |
 * |                                                  |
 * |          Common Control Register                 |
 * |                                                  |
 * |                                                  |
 * |                                                  |
 * +-----------------------+--------------------------+ Base+spad_offset
 * |                       |                          |
 * |    Peer Spad Space    |    Spad Space            |
 * |                       |                          |
 * |                       |                          |
 * +-----------------------+--------------------------+ Base+spad_offset
 * |                       |                          |     +spad_count * 4
 * |                       |                          |
 * |     Spad Space        |   Peer Spad Space        |
 * |                       |                          |
 * +-----------------------+--------------------------+
 *       Virtual PCI             PCIe Endpoint
 *       NTB Driver               NTB Driver
 */
struct epf_ntb_ctrl {
        u32 command;
        u32 argument;
        u16 command_status;
        u16 link_status;
        u32 topology;
        u64 addr;
        u64 size;
        u32 num_mws;
        u32 reserved;
        u32 spad_offset;
        u32 spad_count;
        u32 db_entry_size;
        u32 db_data[MAX_DB_COUNT];
        u32 db_offset[MAX_DB_COUNT];
} __packed;

struct epf_ntb {
        struct ntb_dev ntb;
        struct pci_epf *epf;
        struct config_group group;

        u32 num_mws;
        u32 db_count;
        u32 spad_count;
        u64 mws_size[MAX_MW];
        atomic64_t db;
        u32 vbus_number;
        u16 vntb_pid;
        u16 vntb_vid;

        bool linkup;
        bool msi_doorbell;
        u32 spad_size;

        enum pci_barno epf_ntb_bar[VNTB_BAR_NUM];

        struct epf_ntb_ctrl *reg;

        u32 *epf_db;

        phys_addr_t vpci_mw_phy[MAX_MW];
        void __iomem *vpci_mw_addr[MAX_MW];

        struct delayed_work cmd_handler;
};

#define to_epf_ntb(epf_group) container_of((epf_group), struct epf_ntb, group)
#define ntb_ndev(__ntb) container_of(__ntb, struct epf_ntb, ntb)

static struct pci_epf_header epf_ntb_header = {
        .vendorid       = PCI_ANY_ID,
        .deviceid       = PCI_ANY_ID,
        .baseclass_code = PCI_BASE_CLASS_MEMORY,
        .interrupt_pin  = PCI_INTERRUPT_INTA,
};

/**
 * epf_ntb_link_up() - Raise link_up interrupt to Virtual Host (VHOST)
 * @ntb: NTB device that facilitates communication between HOST and VHOST
 * @link_up: true or false indicating Link is UP or Down
 *
 * Once NTB function in HOST invoke ntb_link_enable(),
 * this NTB function driver will trigger a link event to VHOST.
 *
 * Returns: Zero for success, or an error code in case of failure
 */
static int epf_ntb_link_up(struct epf_ntb *ntb, bool link_up)
{
        if (link_up)
                ntb->reg->link_status |= LINK_STATUS_UP;
        else
                ntb->reg->link_status &= ~LINK_STATUS_UP;

        ntb_link_event(&ntb->ntb);
        return 0;
}

/**
 * epf_ntb_configure_mw() - Configure the Outbound Address Space for VHOST
 *   to access the memory window of HOST
 * @ntb: NTB device that facilitates communication between HOST and VHOST
 * @mw: Index of the memory window (either 0, 1, 2 or 3)
 *
 *                          EP Outbound Window
 * +--------+              +-----------+
 * |        |              |           |
 * |        |              |           |
 * |        |              |           |
 * |        |              |           |
 * |        |              +-----------+
 * | Virtual|              | Memory Win|
 * | NTB    | -----------> |           |
 * | Driver |              |           |
 * |        |              +-----------+
 * |        |              |           |
 * |        |              |           |
 * +--------+              +-----------+
 *  VHOST                   PCI EP
 *
 * Returns: Zero for success, or an error code in case of failure
 */
static int epf_ntb_configure_mw(struct epf_ntb *ntb, u32 mw)
{
        phys_addr_t phys_addr;
        u8 func_no, vfunc_no;
        u64 addr, size;
        int ret = 0;

        phys_addr = ntb->vpci_mw_phy[mw];
        addr = ntb->reg->addr;
        size = ntb->reg->size;

        func_no = ntb->epf->func_no;
        vfunc_no = ntb->epf->vfunc_no;

        ret = pci_epc_map_addr(ntb->epf->epc, func_no, vfunc_no, phys_addr, addr, size);
        if (ret)
                dev_err(&ntb->epf->epc->dev,
                        "Failed to map memory window %d address\n", mw);
        return ret;
}

/**
 * epf_ntb_teardown_mw() - Teardown the configured OB ATU
 * @ntb: NTB device that facilitates communication between HOST and VHOST
 * @mw: Index of the memory window (either 0, 1, 2 or 3)
 *
 * Teardown the configured OB ATU configured in epf_ntb_configure_mw() using
 * pci_epc_unmap_addr()
 */
static void epf_ntb_teardown_mw(struct epf_ntb *ntb, u32 mw)
{
        pci_epc_unmap_addr(ntb->epf->epc,
                           ntb->epf->func_no,
                           ntb->epf->vfunc_no,
                           ntb->vpci_mw_phy[mw]);
}

/**
 * epf_ntb_cmd_handler() - Handle commands provided by the NTB HOST
 * @work: work_struct for the epf_ntb_epc
 *
 * Workqueue function that gets invoked for the two epf_ntb_epc
 * periodically (once every 5ms) to see if it has received any commands
 * from NTB HOST. The HOST can send commands to configure doorbell or
 * configure memory window or to update link status.
 */
static void epf_ntb_cmd_handler(struct work_struct *work)
{
        struct epf_ntb_ctrl *ctrl;
        u32 command, argument;
        struct epf_ntb *ntb;
        struct device *dev;
        int ret;
        int i;

        ntb = container_of(work, struct epf_ntb, cmd_handler.work);

        for (i = 1; i < ntb->db_count && !ntb->msi_doorbell; i++) {
                if (ntb->epf_db[i]) {
                        atomic64_or(1 << (i - 1), &ntb->db);
                        ntb_db_event(&ntb->ntb, i);
                        ntb->epf_db[i] = 0;
                }
        }

        ctrl = ntb->reg;
        command = ctrl->command;
        if (!command)
                goto reset_handler;
        argument = ctrl->argument;

        ctrl->command = 0;
        ctrl->argument = 0;

        ctrl = ntb->reg;
        dev = &ntb->epf->dev;

        switch (command) {
        case COMMAND_CONFIGURE_DOORBELL:
                ctrl->command_status = COMMAND_STATUS_OK;
                break;
        case COMMAND_TEARDOWN_DOORBELL:
                ctrl->command_status = COMMAND_STATUS_OK;
                break;
        case COMMAND_CONFIGURE_MW:
                ret = epf_ntb_configure_mw(ntb, argument);
                if (ret < 0)
                        ctrl->command_status = COMMAND_STATUS_ERROR;
                else
                        ctrl->command_status = COMMAND_STATUS_OK;
                break;
        case COMMAND_TEARDOWN_MW:
                epf_ntb_teardown_mw(ntb, argument);
                ctrl->command_status = COMMAND_STATUS_OK;
                break;
        case COMMAND_LINK_UP:
                ntb->linkup = true;
                ret = epf_ntb_link_up(ntb, true);
                if (ret < 0)
                        ctrl->command_status = COMMAND_STATUS_ERROR;
                else
                        ctrl->command_status = COMMAND_STATUS_OK;
                goto reset_handler;
        case COMMAND_LINK_DOWN:
                ntb->linkup = false;
                ret = epf_ntb_link_up(ntb, false);
                if (ret < 0)
                        ctrl->command_status = COMMAND_STATUS_ERROR;
                else
                        ctrl->command_status = COMMAND_STATUS_OK;
                break;
        default:
                dev_err(dev, "UNKNOWN command: %d\n", command);
                break;
        }

reset_handler:
        queue_delayed_work(kpcintb_workqueue, &ntb->cmd_handler,
                           ntb->msi_doorbell ? msecs_to_jiffies(500) : msecs_to_jiffies(5));
}

static irqreturn_t epf_ntb_doorbell_handler(int irq, void *data)
{
        struct epf_ntb *ntb = data;
        int i;

        for (i = 1; i < ntb->db_count; i++)
                if (irq == ntb->epf->db_msg[i].virq) {
                        atomic64_or(1 << (i - 1), &ntb->db);
                        ntb_db_event(&ntb->ntb, i);
                }

        return IRQ_HANDLED;
}

/**
 * epf_ntb_config_sspad_bar_clear() - Clear Config + Self scratchpad BAR
 * @ntb: EPC associated with one of the HOST which holds peer's outbound
 *       address.
 *
 * Clear BAR0 of EP CONTROLLER 1 which contains the HOST1's config and
 * self scratchpad region (removes inbound ATU configuration). While BAR0 is
 * the default self scratchpad BAR, an NTB could have other BARs for self
 * scratchpad (because of reserved BARs). This function can get the exact BAR
 * used for self scratchpad from epf_ntb_bar[BAR_CONFIG].
 *
 * Please note the self scratchpad region and config region is combined to
 * a single region and mapped using the same BAR. Also note VHOST's peer
 * scratchpad is HOST's self scratchpad.
 *
 * Returns: void
 */
static void epf_ntb_config_sspad_bar_clear(struct epf_ntb *ntb)
{
        struct pci_epf_bar *epf_bar;
        enum pci_barno barno;

        barno = ntb->epf_ntb_bar[BAR_CONFIG];
        epf_bar = &ntb->epf->bar[barno];

        pci_epc_clear_bar(ntb->epf->epc, ntb->epf->func_no, ntb->epf->vfunc_no, epf_bar);
}

/**
 * epf_ntb_config_sspad_bar_set() - Set Config + Self scratchpad BAR
 * @ntb: NTB device that facilitates communication between HOST and VHOST
 *
 * Map BAR0 of EP CONTROLLER which contains the VHOST's config and
 * self scratchpad region.
 *
 * Please note the self scratchpad region and config region is combined to
 * a single region and mapped using the same BAR.
 *
 * Returns: Zero for success, or an error code in case of failure
 */
static int epf_ntb_config_sspad_bar_set(struct epf_ntb *ntb)
{
        struct pci_epf_bar *epf_bar;
        enum pci_barno barno;
        u8 func_no, vfunc_no;
        struct device *dev;
        int ret;

        dev = &ntb->epf->dev;
        func_no = ntb->epf->func_no;
        vfunc_no = ntb->epf->vfunc_no;
        barno = ntb->epf_ntb_bar[BAR_CONFIG];
        epf_bar = &ntb->epf->bar[barno];

        ret = pci_epc_set_bar(ntb->epf->epc, func_no, vfunc_no, epf_bar);
        if (ret) {
                dev_err(dev, "inft: Config/Status/SPAD BAR set failed\n");
                return ret;
        }
        return 0;
}

/**
 * epf_ntb_config_spad_bar_free() - Free the physical memory associated with
 *   config + scratchpad region
 * @ntb: NTB device that facilitates communication between HOST and VHOST
 */
static void epf_ntb_config_spad_bar_free(struct epf_ntb *ntb)
{
        enum pci_barno barno;

        barno = ntb->epf_ntb_bar[BAR_CONFIG];
        pci_epf_free_space(ntb->epf, ntb->reg, barno, 0);
}

/**
 * epf_ntb_config_spad_bar_alloc() - Allocate memory for config + scratchpad
 *   region
 * @ntb: NTB device that facilitates communication between HOST and VHOST
 *
 * Allocate the Local Memory mentioned in the above diagram. The size of
 * CONFIG REGION is sizeof(struct epf_ntb_ctrl) and size of SCRATCHPAD REGION
 * is obtained from "spad-count" configfs entry.
 *
 * Returns: Zero for success, or an error code in case of failure
 */
static int epf_ntb_config_spad_bar_alloc(struct epf_ntb *ntb)
{
        enum pci_barno barno;
        struct epf_ntb_ctrl *ctrl;
        u32 spad_size, ctrl_size;
        struct pci_epf *epf = ntb->epf;
        struct device *dev = &epf->dev;
        u32 spad_count;
        void *base;
        int i;
        const struct pci_epc_features *epc_features = pci_epc_get_features(epf->epc,
                                                                epf->func_no,
                                                                epf->vfunc_no);
        barno = ntb->epf_ntb_bar[BAR_CONFIG];
        spad_count = ntb->spad_count;

        ctrl_size = ALIGN(sizeof(struct epf_ntb_ctrl), sizeof(u32));
        spad_size = 2 * spad_count * sizeof(u32);

        base = pci_epf_alloc_space(epf, ctrl_size + spad_size,
                                   barno, epc_features, 0);
        if (!base) {
                dev_err(dev, "Config/Status/SPAD alloc region fail\n");
                return -ENOMEM;
        }

        ntb->reg = base;

        ctrl = ntb->reg;
        ctrl->spad_offset = ctrl_size;

        ctrl->spad_count = spad_count;
        ctrl->num_mws = ntb->num_mws;
        ntb->spad_size = spad_size;

        ctrl->db_entry_size = sizeof(u32);

        for (i = 0; i < ntb->db_count; i++) {
                ntb->reg->db_data[i] = 1 + i;
                ntb->reg->db_offset[i] = 0;
        }

        return 0;
}

/**
 * epf_ntb_configure_interrupt() - Configure MSI/MSI-X capability
 * @ntb: NTB device that facilitates communication between HOST and VHOST
 *
 * Configure MSI/MSI-X capability for each interface with number of
 * interrupts equal to "db_count" configfs entry.
 *
 * Returns: Zero for success, or an error code in case of failure
 */
static int epf_ntb_configure_interrupt(struct epf_ntb *ntb)
{
        const struct pci_epc_features *epc_features;
        struct device *dev;
        u32 db_count;
        int ret;

        dev = &ntb->epf->dev;

        epc_features = pci_epc_get_features(ntb->epf->epc, ntb->epf->func_no, ntb->epf->vfunc_no);

        if (!(epc_features->msix_capable || epc_features->msi_capable)) {
                dev_err(dev, "MSI or MSI-X is required for doorbell\n");
                return -EINVAL;
        }

        db_count = ntb->db_count;
        if (db_count > MAX_DB_COUNT) {
                dev_err(dev, "DB count cannot be more than %d\n", MAX_DB_COUNT);
                return -EINVAL;
        }

        ntb->db_count = db_count;

        if (epc_features->msi_capable) {
                ret = pci_epc_set_msi(ntb->epf->epc,
                                      ntb->epf->func_no,
                                      ntb->epf->vfunc_no,
                                      16);
                if (ret) {
                        dev_err(dev, "MSI configuration failed\n");
                        return ret;
                }
        }

        return 0;
}

static int epf_ntb_db_bar_init_msi_doorbell(struct epf_ntb *ntb,
                                            struct pci_epf_bar *db_bar,
                                            const struct pci_epc_features *epc_features,
                                            enum pci_barno barno)
{
        struct pci_epf *epf = ntb->epf;
        dma_addr_t low, high;
        struct msi_msg *msg;
        size_t sz;
        int ret;
        int i;

        ret = pci_epf_alloc_doorbell(epf,  ntb->db_count);
        if (ret)
                return ret;

        for (i = 0; i < ntb->db_count; i++) {
                ret = request_irq(epf->db_msg[i].virq, epf_ntb_doorbell_handler,
                                  0, "pci_epf_vntb_db", ntb);

                if (ret) {
                        dev_err(&epf->dev,
                                "Failed to request doorbell IRQ: %d\n",
                                epf->db_msg[i].virq);
                        goto err_free_irq;
                }
        }

        msg = &epf->db_msg[0].msg;

        high = 0;
        low = (u64)msg->address_hi << 32 | msg->address_lo;

        for (i = 0; i < ntb->db_count; i++) {
                struct msi_msg *msg = &epf->db_msg[i].msg;
                dma_addr_t addr = (u64)msg->address_hi << 32 | msg->address_lo;

                low = min(low, addr);
                high = max(high, addr);
        }

        sz = high - low + sizeof(u32);

        ret = pci_epf_assign_bar_space(epf, sz, barno, epc_features, 0, low);
        if (ret) {
                dev_err(&epf->dev, "Failed to assign Doorbell BAR space\n");
                goto err_free_irq;
        }

        ret = pci_epc_set_bar(ntb->epf->epc, ntb->epf->func_no,
                              ntb->epf->vfunc_no, db_bar);
        if (ret) {
                dev_err(&epf->dev, "Failed to set Doorbell BAR\n");
                goto err_free_irq;
        }

        for (i = 0; i < ntb->db_count; i++) {
                struct msi_msg *msg = &epf->db_msg[i].msg;
                dma_addr_t addr;
                size_t offset;

                ret = pci_epf_align_inbound_addr(epf, db_bar->barno,
                                ((u64)msg->address_hi << 32) | msg->address_lo,
                                &addr, &offset);

                if (ret) {
                        ntb->msi_doorbell = false;
                        goto err_free_irq;
                }

                ntb->reg->db_data[i] = msg->data;
                ntb->reg->db_offset[i] = offset;
        }

        ntb->reg->db_entry_size = 0;

        ntb->msi_doorbell = true;

        return 0;

err_free_irq:
        for (i--; i >= 0; i--)
                free_irq(epf->db_msg[i].virq, ntb);

        pci_epf_free_doorbell(ntb->epf);
        return ret;
}

/**
 * epf_ntb_db_bar_init() - Configure Doorbell window BARs
 * @ntb: NTB device that facilitates communication between HOST and VHOST
 *
 * Returns: Zero for success, or an error code in case of failure
 */
static int epf_ntb_db_bar_init(struct epf_ntb *ntb)
{
        const struct pci_epc_features *epc_features;
        struct device *dev = &ntb->epf->dev;
        int ret;
        struct pci_epf_bar *epf_bar;
        void *mw_addr;
        enum pci_barno barno;
        size_t size = sizeof(u32) * ntb->db_count;

        epc_features = pci_epc_get_features(ntb->epf->epc,
                                            ntb->epf->func_no,
                                            ntb->epf->vfunc_no);
        barno = ntb->epf_ntb_bar[BAR_DB];
        epf_bar = &ntb->epf->bar[barno];

        ret = epf_ntb_db_bar_init_msi_doorbell(ntb, epf_bar, epc_features, barno);
        if (ret) {
                /* fall back to polling mode */
                mw_addr = pci_epf_alloc_space(ntb->epf, size, barno, epc_features, 0);
                if (!mw_addr) {
                        dev_err(dev, "Failed to allocate OB address\n");
                        return -ENOMEM;
                }

                ntb->epf_db = mw_addr;

                ret = pci_epc_set_bar(ntb->epf->epc, ntb->epf->func_no,
                                      ntb->epf->vfunc_no, epf_bar);
                if (ret) {
                        dev_err(dev, "Doorbell BAR set failed\n");
                        goto err_alloc_peer_mem;
                }
        }
        return ret;

err_alloc_peer_mem:
        pci_epf_free_space(ntb->epf, mw_addr, barno, 0);
        return -1;
}

static void epf_ntb_mw_bar_clear(struct epf_ntb *ntb, int num_mws);

/**
 * epf_ntb_db_bar_clear() - Clear doorbell BAR and free memory
 *   allocated in peer's outbound address space
 * @ntb: NTB device that facilitates communication between HOST and VHOST
 */
static void epf_ntb_db_bar_clear(struct epf_ntb *ntb)
{
        enum pci_barno barno;

        if (ntb->msi_doorbell) {
                int i;

                for (i = 0; i < ntb->db_count; i++)
                        free_irq(ntb->epf->db_msg[i].virq, ntb);
        }

        if (ntb->epf->db_msg)
                pci_epf_free_doorbell(ntb->epf);

        barno = ntb->epf_ntb_bar[BAR_DB];
        pci_epf_free_space(ntb->epf, ntb->epf_db, barno, 0);
        pci_epc_clear_bar(ntb->epf->epc,
                          ntb->epf->func_no,
                          ntb->epf->vfunc_no,
                          &ntb->epf->bar[barno]);
}

/**
 * epf_ntb_mw_bar_init() - Configure Memory window BARs
 * @ntb: NTB device that facilitates communication between HOST and VHOST
 *
 * Returns: Zero for success, or an error code in case of failure
 */
static int epf_ntb_mw_bar_init(struct epf_ntb *ntb)
{
        int ret = 0;
        int i;
        u64 size;
        enum pci_barno barno;
        struct device *dev = &ntb->epf->dev;

        for (i = 0; i < ntb->num_mws; i++) {
                size = ntb->mws_size[i];
                barno = ntb->epf_ntb_bar[BAR_MW1 + i];

                ntb->epf->bar[barno].barno = barno;
                ntb->epf->bar[barno].size = size;
                ntb->epf->bar[barno].addr = NULL;
                ntb->epf->bar[barno].phys_addr = 0;
                ntb->epf->bar[barno].flags |= upper_32_bits(size) ?
                                PCI_BASE_ADDRESS_MEM_TYPE_64 :
                                PCI_BASE_ADDRESS_MEM_TYPE_32;

                ret = pci_epc_set_bar(ntb->epf->epc,
                                      ntb->epf->func_no,
                                      ntb->epf->vfunc_no,
                                      &ntb->epf->bar[barno]);
                if (ret) {
                        dev_err(dev, "MW set failed\n");
                        goto err_alloc_mem;
                }

                /* Allocate EPC outbound memory windows to vpci vntb device */
                ntb->vpci_mw_addr[i] = pci_epc_mem_alloc_addr(ntb->epf->epc,
                                                              &ntb->vpci_mw_phy[i],
                                                              size);
                if (!ntb->vpci_mw_addr[i]) {
                        ret = -ENOMEM;
                        dev_err(dev, "Failed to allocate source address\n");
                        goto err_set_bar;
                }
        }

        return ret;

err_set_bar:
        pci_epc_clear_bar(ntb->epf->epc,
                          ntb->epf->func_no,
                          ntb->epf->vfunc_no,
                          &ntb->epf->bar[barno]);
err_alloc_mem:
        epf_ntb_mw_bar_clear(ntb, i);
        return ret;
}

/**
 * epf_ntb_mw_bar_clear() - Clear Memory window BARs
 * @ntb: NTB device that facilitates communication between HOST and VHOST
 * @num_mws: the number of Memory window BARs that to be cleared
 */
static void epf_ntb_mw_bar_clear(struct epf_ntb *ntb, int num_mws)
{
        enum pci_barno barno;
        int i;

        for (i = 0; i < num_mws; i++) {
                barno = ntb->epf_ntb_bar[BAR_MW1 + i];
                pci_epc_clear_bar(ntb->epf->epc,
                                  ntb->epf->func_no,
                                  ntb->epf->vfunc_no,
                                  &ntb->epf->bar[barno]);

                pci_epc_mem_free_addr(ntb->epf->epc,
                                      ntb->vpci_mw_phy[i],
                                      ntb->vpci_mw_addr[i],
                                      ntb->mws_size[i]);
        }
}

/**
 * epf_ntb_epc_destroy() - Cleanup NTB EPC interface
 * @ntb: NTB device that facilitates communication between HOST and VHOST
 *
 * Wrapper for epf_ntb_epc_destroy_interface() to cleanup all the NTB interfaces
 */
static void epf_ntb_epc_destroy(struct epf_ntb *ntb)
{
        pci_epc_remove_epf(ntb->epf->epc, ntb->epf, 0);
        pci_epc_put(ntb->epf->epc);
}


/**
 * epf_ntb_is_bar_used() - Check if a bar is used in the ntb configuration
 * @ntb: NTB device that facilitates communication between HOST and VHOST
 * @barno: Checked bar number
 *
 * Returns: true if used, false if free.
 */
static bool epf_ntb_is_bar_used(struct epf_ntb *ntb,
                                enum pci_barno barno)
{
        int i;

        for (i = 0; i < VNTB_BAR_NUM; i++) {
                if (ntb->epf_ntb_bar[i] == barno)
                        return true;
        }

        return false;
}

/**
 * epf_ntb_find_bar() - Assign BAR number when no configuration is provided
 * @ntb: NTB device that facilitates communication between HOST and VHOST
 * @epc_features: The features provided by the EPC specific to this EPF
 * @bar: NTB BAR index
 * @barno: Bar start index
 *
 * When the BAR configuration was not provided through the userspace
 * configuration, automatically assign BAR as it has been historically
 * done by this endpoint function.
 *
 * Returns: the BAR number found, if any. -1 otherwise
 */
static int epf_ntb_find_bar(struct epf_ntb *ntb,
                            const struct pci_epc_features *epc_features,
                            enum epf_ntb_bar bar,
                            enum pci_barno barno)
{
        while (ntb->epf_ntb_bar[bar] < 0) {
                barno = pci_epc_get_next_free_bar(epc_features, barno);
                if (barno < 0)
                        break; /* No more BAR available */

                /*
                 * Verify if the BAR found is not already assigned
                 * through the provided configuration
                 */
                if (!epf_ntb_is_bar_used(ntb, barno))
                        ntb->epf_ntb_bar[bar] = barno;

                barno += 1;
        }

        return barno;
}

/**
 * epf_ntb_init_epc_bar() - Identify BARs to be used for each of the NTB
 * constructs (scratchpad region, doorbell, memorywindow)
 * @ntb: NTB device that facilitates communication between HOST and VHOST
 *
 * Returns: Zero for success, or an error code in case of failure
 */
static int epf_ntb_init_epc_bar(struct epf_ntb *ntb)
{
        const struct pci_epc_features *epc_features;
        enum pci_barno barno;
        enum epf_ntb_bar bar;
        struct device *dev;
        u32 num_mws;
        int i;

        barno = BAR_0;
        num_mws = ntb->num_mws;
        dev = &ntb->epf->dev;
        epc_features = pci_epc_get_features(ntb->epf->epc, ntb->epf->func_no, ntb->epf->vfunc_no);

        /* These are required BARs which are mandatory for NTB functionality */
        for (bar = BAR_CONFIG; bar <= BAR_MW1; bar++) {
                barno = epf_ntb_find_bar(ntb, epc_features, bar, barno);
                if (barno < 0) {
                        dev_err(dev, "Fail to get NTB function BAR\n");
                        return -ENOENT;
                }
        }

        /* These are optional BARs which don't impact NTB functionality */
        for (bar = BAR_MW1, i = 1; i < num_mws; bar++, i++) {
                barno = epf_ntb_find_bar(ntb, epc_features, bar, barno);
                if (barno < 0) {
                        ntb->num_mws = i;
                        dev_dbg(dev, "BAR not available for > MW%d\n", i + 1);
                }
        }

        return 0;
}

/**
 * epf_ntb_epc_init() - Initialize NTB interface
 * @ntb: NTB device that facilitates communication between HOST and VHOST
 *
 * Wrapper to initialize a particular EPC interface and start the workqueue
 * to check for commands from HOST. This function will write to the
 * EP controller HW for configuring it.
 *
 * Returns: Zero for success, or an error code in case of failure
 */
static int epf_ntb_epc_init(struct epf_ntb *ntb)
{
        u8 func_no, vfunc_no;
        struct pci_epc *epc;
        struct pci_epf *epf;
        struct device *dev;
        int ret;

        epf = ntb->epf;
        dev = &epf->dev;
        epc = epf->epc;
        func_no = ntb->epf->func_no;
        vfunc_no = ntb->epf->vfunc_no;

        ret = epf_ntb_config_sspad_bar_set(ntb);
        if (ret) {
                dev_err(dev, "Config/self SPAD BAR init failed");
                return ret;
        }

        ret = epf_ntb_configure_interrupt(ntb);
        if (ret) {
                dev_err(dev, "Interrupt configuration failed\n");
                goto err_config_interrupt;
        }

        ret = epf_ntb_db_bar_init(ntb);
        if (ret) {
                dev_err(dev, "DB BAR init failed\n");
                goto err_db_bar_init;
        }

        ret = epf_ntb_mw_bar_init(ntb);
        if (ret) {
                dev_err(dev, "MW BAR init failed\n");
                goto err_mw_bar_init;
        }

        if (vfunc_no <= 1) {
                ret = pci_epc_write_header(epc, func_no, vfunc_no, epf->header);
                if (ret) {
                        dev_err(dev, "Configuration header write failed\n");
                        goto err_write_header;
                }
        }

        INIT_DELAYED_WORK(&ntb->cmd_handler, epf_ntb_cmd_handler);
        queue_work(kpcintb_workqueue, &ntb->cmd_handler.work);

        return 0;

err_write_header:
        epf_ntb_mw_bar_clear(ntb, ntb->num_mws);
err_mw_bar_init:
        epf_ntb_db_bar_clear(ntb);
err_db_bar_init:
err_config_interrupt:
        epf_ntb_config_sspad_bar_clear(ntb);

        return ret;
}


/**
 * epf_ntb_epc_cleanup() - Cleanup all NTB interfaces
 * @ntb: NTB device that facilitates communication between HOST and VHOST
 *
 * Wrapper to cleanup all NTB interfaces.
 */
static void epf_ntb_epc_cleanup(struct epf_ntb *ntb)
{
        epf_ntb_mw_bar_clear(ntb, ntb->num_mws);
        epf_ntb_db_bar_clear(ntb);
        epf_ntb_config_sspad_bar_clear(ntb);
}

#define EPF_NTB_R(_name)                                                \
static ssize_t epf_ntb_##_name##_show(struct config_item *item,         \
                                      char *page)                       \
{                                                                       \
        struct config_group *group = to_config_group(item);             \
        struct epf_ntb *ntb = to_epf_ntb(group);                        \
                                                                        \
        return sprintf(page, "%d\n", ntb->_name);                       \
}

#define EPF_NTB_W(_name)                                                \
static ssize_t epf_ntb_##_name##_store(struct config_item *item,        \
                                       const char *page, size_t len)    \
{                                                                       \
        struct config_group *group = to_config_group(item);             \
        struct epf_ntb *ntb = to_epf_ntb(group);                        \
        u32 val;                                                        \
        int ret;                                                        \
                                                                        \
        ret = kstrtou32(page, 0, &val);                                 \
        if (ret)                                                        \
                return ret;                                             \
                                                                        \
        ntb->_name = val;                                               \
                                                                        \
        return len;                                                     \
}

#define EPF_NTB_MW_R(_name)                                             \
static ssize_t epf_ntb_##_name##_show(struct config_item *item,         \
                                      char *page)                       \
{                                                                       \
        struct config_group *group = to_config_group(item);             \
        struct epf_ntb *ntb = to_epf_ntb(group);                        \
        struct device *dev = &ntb->epf->dev;                            \
        int win_no;                                                     \
                                                                        \
        if (sscanf(#_name, "mw%d", &win_no) != 1)                       \
                return -EINVAL;                                         \
                                                                        \
        if (win_no <= 0 || win_no > ntb->num_mws) {                     \
                dev_err(dev, "Invalid num_nws: %d value\n", ntb->num_mws); \
                return -EINVAL;                                         \
        }                                                               \
                                                                        \
        return sprintf(page, "%lld\n", ntb->mws_size[win_no - 1]);      \
}

#define EPF_NTB_MW_W(_name)                                             \
static ssize_t epf_ntb_##_name##_store(struct config_item *item,        \
                                       const char *page, size_t len)    \
{                                                                       \
        struct config_group *group = to_config_group(item);             \
        struct epf_ntb *ntb = to_epf_ntb(group);                        \
        struct device *dev = &ntb->epf->dev;                            \
        int win_no;                                                     \
        u64 val;                                                        \
        int ret;                                                        \
                                                                        \
        ret = kstrtou64(page, 0, &val);                                 \
        if (ret)                                                        \
                return ret;                                             \
                                                                        \
        if (sscanf(#_name, "mw%d", &win_no) != 1)                       \
                return -EINVAL;                                         \
                                                                        \
        if (win_no <= 0 || win_no > ntb->num_mws) {                     \
                dev_err(dev, "Invalid num_nws: %d value\n", ntb->num_mws); \
                return -EINVAL;                                         \
        }                                                               \
                                                                        \
        ntb->mws_size[win_no - 1] = val;                                \
                                                                        \
        return len;                                                     \
}

#define EPF_NTB_BAR_R(_name, _id)                                       \
        static ssize_t epf_ntb_##_name##_show(struct config_item *item, \
                                              char *page)               \
        {                                                               \
                struct config_group *group = to_config_group(item);     \
                struct epf_ntb *ntb = to_epf_ntb(group);                \
                                                                        \
                return sprintf(page, "%d\n", ntb->epf_ntb_bar[_id]);    \
        }

#define EPF_NTB_BAR_W(_name, _id)                                       \
        static ssize_t epf_ntb_##_name##_store(struct config_item *item, \
                                               const char *page, size_t len) \
        {                                                               \
                struct config_group *group = to_config_group(item);     \
                struct epf_ntb *ntb = to_epf_ntb(group);                \
                int val;                                                \
                int ret;                                                \
                                                                        \
                ret = kstrtoint(page, 0, &val);                         \
                if (ret)                                                \
                        return ret;                                     \
                                                                        \
                if (val < NO_BAR || val > BAR_5)                        \
                        return -EINVAL;                                 \
                                                                        \
                ntb->epf_ntb_bar[_id] = val;                            \
                                                                        \
                return len;                                             \
        }

static ssize_t epf_ntb_num_mws_store(struct config_item *item,
                                     const char *page, size_t len)
{
        struct config_group *group = to_config_group(item);
        struct epf_ntb *ntb = to_epf_ntb(group);
        u32 val;
        int ret;

        ret = kstrtou32(page, 0, &val);
        if (ret)
                return ret;

        if (val > MAX_MW)
                return -EINVAL;

        ntb->num_mws = val;

        return len;
}

EPF_NTB_R(spad_count)
EPF_NTB_W(spad_count)
EPF_NTB_R(db_count)
EPF_NTB_W(db_count)
EPF_NTB_R(num_mws)
EPF_NTB_R(vbus_number)
EPF_NTB_W(vbus_number)
EPF_NTB_R(vntb_pid)
EPF_NTB_W(vntb_pid)
EPF_NTB_R(vntb_vid)
EPF_NTB_W(vntb_vid)
EPF_NTB_MW_R(mw1)
EPF_NTB_MW_W(mw1)
EPF_NTB_MW_R(mw2)
EPF_NTB_MW_W(mw2)
EPF_NTB_MW_R(mw3)
EPF_NTB_MW_W(mw3)
EPF_NTB_MW_R(mw4)
EPF_NTB_MW_W(mw4)
EPF_NTB_BAR_R(ctrl_bar, BAR_CONFIG)
EPF_NTB_BAR_W(ctrl_bar, BAR_CONFIG)
EPF_NTB_BAR_R(db_bar, BAR_DB)
EPF_NTB_BAR_W(db_bar, BAR_DB)
EPF_NTB_BAR_R(mw1_bar, BAR_MW1)
EPF_NTB_BAR_W(mw1_bar, BAR_MW1)
EPF_NTB_BAR_R(mw2_bar, BAR_MW2)
EPF_NTB_BAR_W(mw2_bar, BAR_MW2)
EPF_NTB_BAR_R(mw3_bar, BAR_MW3)
EPF_NTB_BAR_W(mw3_bar, BAR_MW3)
EPF_NTB_BAR_R(mw4_bar, BAR_MW4)
EPF_NTB_BAR_W(mw4_bar, BAR_MW4)

CONFIGFS_ATTR(epf_ntb_, spad_count);
CONFIGFS_ATTR(epf_ntb_, db_count);
CONFIGFS_ATTR(epf_ntb_, num_mws);
CONFIGFS_ATTR(epf_ntb_, mw1);
CONFIGFS_ATTR(epf_ntb_, mw2);
CONFIGFS_ATTR(epf_ntb_, mw3);
CONFIGFS_ATTR(epf_ntb_, mw4);
CONFIGFS_ATTR(epf_ntb_, vbus_number);
CONFIGFS_ATTR(epf_ntb_, vntb_pid);
CONFIGFS_ATTR(epf_ntb_, vntb_vid);
CONFIGFS_ATTR(epf_ntb_, ctrl_bar);
CONFIGFS_ATTR(epf_ntb_, db_bar);
CONFIGFS_ATTR(epf_ntb_, mw1_bar);
CONFIGFS_ATTR(epf_ntb_, mw2_bar);
CONFIGFS_ATTR(epf_ntb_, mw3_bar);
CONFIGFS_ATTR(epf_ntb_, mw4_bar);

static struct configfs_attribute *epf_ntb_attrs[] = {
        &epf_ntb_attr_spad_count,
        &epf_ntb_attr_db_count,
        &epf_ntb_attr_num_mws,
        &epf_ntb_attr_mw1,
        &epf_ntb_attr_mw2,
        &epf_ntb_attr_mw3,
        &epf_ntb_attr_mw4,
        &epf_ntb_attr_vbus_number,
        &epf_ntb_attr_vntb_pid,
        &epf_ntb_attr_vntb_vid,
        &epf_ntb_attr_ctrl_bar,
        &epf_ntb_attr_db_bar,
        &epf_ntb_attr_mw1_bar,
        &epf_ntb_attr_mw2_bar,
        &epf_ntb_attr_mw3_bar,
        &epf_ntb_attr_mw4_bar,
        NULL,
};

static const struct config_item_type ntb_group_type = {
        .ct_attrs       = epf_ntb_attrs,
        .ct_owner       = THIS_MODULE,
};

/**
 * epf_ntb_add_cfs() - Add configfs directory specific to NTB
 * @epf: NTB endpoint function device
 * @group: A pointer to the config_group structure referencing a group of
 *         config_items of a specific type that belong to a specific sub-system.
 *
 * Add configfs directory specific to NTB. This directory will hold
 * NTB specific properties like db_count, spad_count, num_mws etc.,
 *
 * Returns: Pointer to config_group
 */
static struct config_group *epf_ntb_add_cfs(struct pci_epf *epf,
                                            struct config_group *group)
{
        struct epf_ntb *ntb = epf_get_drvdata(epf);
        struct config_group *ntb_group = &ntb->group;
        struct device *dev = &epf->dev;

        config_group_init_type_name(ntb_group, dev_name(dev), &ntb_group_type);

        return ntb_group;
}

/*==== virtual PCI bus driver, which only load virtual NTB PCI driver ====*/

static u32 pci_space[] = {
        0xffffffff,     /* Device ID, Vendor ID */
        0,              /* Status, Command */
        0xffffffff,     /* Base Class, Subclass, Prog Intf, Revision ID */
        0x40,           /* BIST, Header Type, Latency Timer, Cache Line Size */
        0,              /* BAR 0 */
        0,              /* BAR 1 */
        0,              /* BAR 2 */
        0,              /* BAR 3 */
        0,              /* BAR 4 */
        0,              /* BAR 5 */
        0,              /* Cardbus CIS Pointer */
        0,              /* Subsystem ID, Subsystem Vendor ID */
        0,              /* ROM Base Address */
        0,              /* Reserved, Capabilities Pointer */
        0,              /* Reserved */
        0,              /* Max_Lat, Min_Gnt, Interrupt Pin, Interrupt Line */
};

static int pci_read(struct pci_bus *bus, unsigned int devfn, int where, int size, u32 *val)
{
        if (devfn == 0) {
                memcpy(val, ((u8 *)pci_space) + where, size);
                return PCIBIOS_SUCCESSFUL;
        }
        return PCIBIOS_DEVICE_NOT_FOUND;
}

static int pci_write(struct pci_bus *bus, unsigned int devfn, int where, int size, u32 val)
{
        return 0;
}

static struct pci_ops vpci_ops = {
        .read = pci_read,
        .write = pci_write,
};

static int vpci_scan_bus(void *sysdata)
{
        struct pci_bus *vpci_bus;
        struct epf_ntb *ndev = sysdata;

        vpci_bus = pci_scan_bus(ndev->vbus_number, &vpci_ops, sysdata);
        if (!vpci_bus) {
                pr_err("create pci bus failed\n");
                return -EINVAL;
        }

        pci_bus_add_devices(vpci_bus);

        return 0;
}

/*==================== Virtual PCIe NTB driver ==========================*/

static int vntb_epf_mw_count(struct ntb_dev *ntb, int pidx)
{
        struct epf_ntb *ndev = ntb_ndev(ntb);

        return ndev->num_mws;
}

static int vntb_epf_spad_count(struct ntb_dev *ntb)
{
        return ntb_ndev(ntb)->spad_count;
}

static int vntb_epf_peer_mw_count(struct ntb_dev *ntb)
{
        return ntb_ndev(ntb)->num_mws;
}

static u64 vntb_epf_db_valid_mask(struct ntb_dev *ntb)
{
        return BIT_ULL(ntb_ndev(ntb)->db_count) - 1;
}

static int vntb_epf_db_set_mask(struct ntb_dev *ntb, u64 db_bits)
{
        return 0;
}

static int vntb_epf_mw_set_trans(struct ntb_dev *ndev, int pidx, int idx,
                dma_addr_t addr, resource_size_t size)
{
        struct epf_ntb *ntb = ntb_ndev(ndev);
        struct pci_epf_bar *epf_bar;
        enum pci_barno barno;
        int ret;
        struct device *dev;

        dev = &ntb->ntb.dev;
        barno = ntb->epf_ntb_bar[BAR_MW1 + idx];
        epf_bar = &ntb->epf->bar[barno];
        epf_bar->phys_addr = addr;
        epf_bar->barno = barno;
        epf_bar->size = size;

        ret = pci_epc_set_bar(ntb->epf->epc, 0, 0, epf_bar);
        if (ret) {
                dev_err(dev, "failure set mw trans\n");
                return ret;
        }
        return 0;
}

static int vntb_epf_mw_clear_trans(struct ntb_dev *ntb, int pidx, int idx)
{
        return 0;
}

static int vntb_epf_peer_mw_get_addr(struct ntb_dev *ndev, int idx,
                                phys_addr_t *base, resource_size_t *size)
{

        struct epf_ntb *ntb = ntb_ndev(ndev);

        if (base)
                *base = ntb->vpci_mw_phy[idx];

        if (size)
                *size = ntb->mws_size[idx];

        return 0;
}

static int vntb_epf_link_enable(struct ntb_dev *ntb,
                        enum ntb_speed max_speed,
                        enum ntb_width max_width)
{
        return 0;
}

static u32 vntb_epf_spad_read(struct ntb_dev *ndev, int idx)
{
        struct epf_ntb *ntb = ntb_ndev(ndev);
        int off = ntb->reg->spad_offset, ct = ntb->reg->spad_count * sizeof(u32);
        u32 val;
        void __iomem *base = (void __iomem *)ntb->reg;

        val = readl(base + off + ct + idx * sizeof(u32));
        return val;
}

static int vntb_epf_spad_write(struct ntb_dev *ndev, int idx, u32 val)
{
        struct epf_ntb *ntb = ntb_ndev(ndev);
        struct epf_ntb_ctrl *ctrl = ntb->reg;
        int off = ctrl->spad_offset, ct = ctrl->spad_count * sizeof(u32);
        void __iomem *base = (void __iomem *)ntb->reg;

        writel(val, base + off + ct + idx * sizeof(u32));
        return 0;
}

static u32 vntb_epf_peer_spad_read(struct ntb_dev *ndev, int pidx, int idx)
{
        struct epf_ntb *ntb = ntb_ndev(ndev);
        struct epf_ntb_ctrl *ctrl = ntb->reg;
        int off = ctrl->spad_offset;
        void __iomem *base = (void __iomem *)ntb->reg;
        u32 val;

        val = readl(base + off + idx * sizeof(u32));
        return val;
}

static int vntb_epf_peer_spad_write(struct ntb_dev *ndev, int pidx, int idx, u32 val)
{
        struct epf_ntb *ntb = ntb_ndev(ndev);
        struct epf_ntb_ctrl *ctrl = ntb->reg;
        int off = ctrl->spad_offset;
        void __iomem *base = (void __iomem *)ntb->reg;

        writel(val, base + off + idx * sizeof(u32));
        return 0;
}

static int vntb_epf_peer_db_set(struct ntb_dev *ndev, u64 db_bits)
{
        u32 interrupt_num = ffs(db_bits) + 1;
        struct epf_ntb *ntb = ntb_ndev(ndev);
        u8 func_no, vfunc_no;
        int ret;

        func_no = ntb->epf->func_no;
        vfunc_no = ntb->epf->vfunc_no;

        ret = pci_epc_raise_irq(ntb->epf->epc, func_no, vfunc_no,
                                PCI_IRQ_MSI, interrupt_num + 1);
        if (ret)
                dev_err(&ntb->ntb.dev, "Failed to raise IRQ\n");

        return ret;
}

static u64 vntb_epf_db_read(struct ntb_dev *ndev)
{
        struct epf_ntb *ntb = ntb_ndev(ndev);

        return atomic64_read(&ntb->db);
}

static int vntb_epf_mw_get_align(struct ntb_dev *ndev, int pidx, int idx,
                        resource_size_t *addr_align,
                        resource_size_t *size_align,
                        resource_size_t *size_max)
{
        struct epf_ntb *ntb = ntb_ndev(ndev);

        if (addr_align)
                *addr_align = SZ_4K;

        if (size_align)
                *size_align = 1;

        if (size_max)
                *size_max = ntb->mws_size[idx];

        return 0;
}

static u64 vntb_epf_link_is_up(struct ntb_dev *ndev,
                        enum ntb_speed *speed,
                        enum ntb_width *width)
{
        struct epf_ntb *ntb = ntb_ndev(ndev);

        return ntb->reg->link_status;
}

static int vntb_epf_db_clear_mask(struct ntb_dev *ndev, u64 db_bits)
{
        return 0;
}

static int vntb_epf_db_clear(struct ntb_dev *ndev, u64 db_bits)
{
        struct epf_ntb *ntb = ntb_ndev(ndev);

        atomic64_and(~db_bits, &ntb->db);
        return 0;
}

static int vntb_epf_link_disable(struct ntb_dev *ntb)
{
        return 0;
}

static const struct ntb_dev_ops vntb_epf_ops = {
        .mw_count               = vntb_epf_mw_count,
        .spad_count             = vntb_epf_spad_count,
        .peer_mw_count          = vntb_epf_peer_mw_count,
        .db_valid_mask          = vntb_epf_db_valid_mask,
        .db_set_mask            = vntb_epf_db_set_mask,
        .mw_set_trans           = vntb_epf_mw_set_trans,
        .mw_clear_trans         = vntb_epf_mw_clear_trans,
        .peer_mw_get_addr       = vntb_epf_peer_mw_get_addr,
        .link_enable            = vntb_epf_link_enable,
        .spad_read              = vntb_epf_spad_read,
        .spad_write             = vntb_epf_spad_write,
        .peer_spad_read         = vntb_epf_peer_spad_read,
        .peer_spad_write        = vntb_epf_peer_spad_write,
        .peer_db_set            = vntb_epf_peer_db_set,
        .db_read                = vntb_epf_db_read,
        .mw_get_align           = vntb_epf_mw_get_align,
        .link_is_up             = vntb_epf_link_is_up,
        .db_clear_mask          = vntb_epf_db_clear_mask,
        .db_clear               = vntb_epf_db_clear,
        .link_disable           = vntb_epf_link_disable,
};

static int pci_vntb_probe(struct pci_dev *pdev, const struct pci_device_id *id)
{
        int ret;
        struct epf_ntb *ndev = (struct epf_ntb *)pdev->sysdata;
        struct device *dev = &pdev->dev;

        ndev->ntb.pdev = pdev;
        ndev->ntb.topo = NTB_TOPO_NONE;
        ndev->ntb.ops =  &vntb_epf_ops;

        ret = dma_set_mask_and_coherent(dev, DMA_BIT_MASK(32));
        if (ret) {
                dev_err(dev, "Cannot set DMA mask\n");
                return ret;
        }

        ret = ntb_register_device(&ndev->ntb);
        if (ret) {
                dev_err(dev, "Failed to register NTB device\n");
                return ret;
        }

        dev_dbg(dev, "PCI Virtual NTB driver loaded\n");
        return 0;
}

static struct pci_device_id pci_vntb_table[] = {
        {
                PCI_DEVICE(0xffff, 0xffff),
        },
        {},
};

static struct pci_driver vntb_pci_driver = {
        .name           = "pci-vntb",
        .id_table       = pci_vntb_table,
        .probe          = pci_vntb_probe,
};

/* ============ PCIe EPF Driver Bind ====================*/

/**
 * epf_ntb_bind() - Initialize endpoint controller to provide NTB functionality
 * @epf: NTB endpoint function device
 *
 * Initialize both the endpoint controllers associated with NTB function device.
 * Invoked when a primary interface or secondary interface is bound to EPC
 * device. This function will succeed only when EPC is bound to both the
 * interfaces.
 *
 * Returns: Zero for success, or an error code in case of failure
 */
static int epf_ntb_bind(struct pci_epf *epf)
{
        struct epf_ntb *ntb = epf_get_drvdata(epf);
        struct device *dev = &epf->dev;
        int ret;

        if (!epf->epc) {
                dev_dbg(dev, "PRIMARY EPC interface not yet bound\n");
                return 0;
        }

        ret = epf_ntb_init_epc_bar(ntb);
        if (ret) {
                dev_err(dev, "Failed to create NTB EPC\n");
                goto err_bar_init;
        }

        ret = epf_ntb_config_spad_bar_alloc(ntb);
        if (ret) {
                dev_err(dev, "Failed to allocate BAR memory\n");
                goto err_bar_alloc;
        }

        ret = epf_ntb_epc_init(ntb);
        if (ret) {
                dev_err(dev, "Failed to initialize EPC\n");
                goto err_bar_alloc;
        }

        epf_set_drvdata(epf, ntb);

        pci_space[0] = (ntb->vntb_pid << 16) | ntb->vntb_vid;
        pci_vntb_table[0].vendor = ntb->vntb_vid;
        pci_vntb_table[0].device = ntb->vntb_pid;

        ret = pci_register_driver(&vntb_pci_driver);
        if (ret) {
                dev_err(dev, "failure register vntb pci driver\n");
                goto err_epc_cleanup;
        }

        ret = vpci_scan_bus(ntb);
        if (ret)
                goto err_unregister;

        return 0;

err_unregister:
        pci_unregister_driver(&vntb_pci_driver);
err_epc_cleanup:
        epf_ntb_epc_cleanup(ntb);
err_bar_alloc:
        epf_ntb_config_spad_bar_free(ntb);

err_bar_init:
        epf_ntb_epc_destroy(ntb);

        return ret;
}

/**
 * epf_ntb_unbind() - Cleanup the initialization from epf_ntb_bind()
 * @epf: NTB endpoint function device
 *
 * Cleanup the initialization from epf_ntb_bind()
 */
static void epf_ntb_unbind(struct pci_epf *epf)
{
        struct epf_ntb *ntb = epf_get_drvdata(epf);

        epf_ntb_epc_cleanup(ntb);
        epf_ntb_config_spad_bar_free(ntb);
        epf_ntb_epc_destroy(ntb);

        pci_unregister_driver(&vntb_pci_driver);
}

// EPF driver probe
static const struct pci_epf_ops epf_ntb_ops = {
        .bind   = epf_ntb_bind,
        .unbind = epf_ntb_unbind,
        .add_cfs = epf_ntb_add_cfs,
};

/**
 * epf_ntb_probe() - Probe NTB function driver
 * @epf: NTB endpoint function device
 * @id: NTB endpoint function device ID
 *
 * Probe NTB function driver when endpoint function bus detects a NTB
 * endpoint function.
 *
 * Returns: Zero for success, or an error code in case of failure
 */
static int epf_ntb_probe(struct pci_epf *epf,
                         const struct pci_epf_device_id *id)
{
        struct epf_ntb *ntb;
        struct device *dev;
        int i;

        dev = &epf->dev;

        ntb = devm_kzalloc(dev, sizeof(*ntb), GFP_KERNEL);
        if (!ntb)
                return -ENOMEM;

        epf->header = &epf_ntb_header;
        ntb->epf = epf;
        ntb->vbus_number = 0xff;

        /* Initially, no bar is assigned */
        for (i = 0; i < VNTB_BAR_NUM; i++)
                ntb->epf_ntb_bar[i] = NO_BAR;

        epf_set_drvdata(epf, ntb);

        dev_info(dev, "pci-ep epf driver loaded\n");
        return 0;
}

static const struct pci_epf_device_id epf_ntb_ids[] = {
        {
                .name = "pci_epf_vntb",
        },
        {},
};

static struct pci_epf_driver epf_ntb_driver = {
        .driver.name    = "pci_epf_vntb",
        .probe          = epf_ntb_probe,
        .id_table       = epf_ntb_ids,
        .ops            = &epf_ntb_ops,
        .owner          = THIS_MODULE,
};

static int __init epf_ntb_init(void)
{
        int ret;

        kpcintb_workqueue = alloc_workqueue("kpcintb",
                                    WQ_MEM_RECLAIM | WQ_HIGHPRI | WQ_PERCPU, 0);
        if (!kpcintb_workqueue) {
                pr_err("Failed to allocate kpcintb workqueue\n");
                return -ENOMEM;
        }

        ret = pci_epf_register_driver(&epf_ntb_driver);
        if (ret) {
                destroy_workqueue(kpcintb_workqueue);
                pr_err("Failed to register pci epf ntb driver --> %d\n", ret);
                return ret;
        }

        return 0;
}
module_init(epf_ntb_init);

static void __exit epf_ntb_exit(void)
{
        pci_epf_unregister_driver(&epf_ntb_driver);
        destroy_workqueue(kpcintb_workqueue);
}
module_exit(epf_ntb_exit);

MODULE_DESCRIPTION("PCI EPF NTB DRIVER");
MODULE_AUTHOR("Frank Li <Frank.li@nxp.com>");
MODULE_LICENSE("GPL v2");