// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * nosy - Snoop mode driver for TI PCILynx 1394 controllers
 * Copyright (C) 2002-2007 Kristian Høgsberg
 */

#include <linux/device.h>
#include <linux/errno.h>
#include <linux/fs.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/kref.h>
#include <linux/miscdevice.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/pci.h>
#include <linux/poll.h>
#include <linux/sched.h> /* required for linux/wait.h */
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/time64.h>
#include <linux/timex.h>
#include <linux/uaccess.h>
#include <linux/wait.h>
#include <linux/dma-mapping.h>
#include <linux/atomic.h>
#include <asm/byteorder.h>

#include "nosy.h"
#include "nosy-user.h"

#define TCODE_PHY_PACKET                0x10
#define PCI_DEVICE_ID_TI_PCILYNX        0x8000

static char driver_name[] = KBUILD_MODNAME;

#define RCV_BUFFER_SIZE (16 * 1024)

/* this is the physical layout of a PCL, its size is 128 bytes */
struct pcl {
        __le32 next;
        __le32 async_error_next;
        u32 user_data;
        __le32 pcl_status;
        __le32 remaining_transfer_count;
        __le32 next_data_buffer;
        struct {
                __le32 control;
                __le32 pointer;
        } buffer[13];
};

struct packet {
        unsigned int length;
        char data[];
};

struct packet_buffer {
        char *data;
        size_t capacity;
        long total_packet_count, lost_packet_count;
        atomic_t size;
        struct packet *head, *tail;
        wait_queue_head_t wait;
};

struct pcilynx {
        struct pci_dev *pci_device;
        __iomem char *registers;

        struct pcl *rcv_start_pcl, *rcv_pcl;
        __le32 *rcv_buffer;

        dma_addr_t rcv_start_pcl_bus, rcv_pcl_bus, rcv_buffer_bus;

        spinlock_t client_list_lock;
        struct list_head client_list;

        struct miscdevice misc;
        struct list_head link;
        struct kref kref;
};

static inline struct pcilynx *
lynx_get(struct pcilynx *lynx)
{
        kref_get(&lynx->kref);

        return lynx;
}

static void
lynx_release(struct kref *kref)
{
        kfree(container_of(kref, struct pcilynx, kref));
}

static inline void
lynx_put(struct pcilynx *lynx)
{
        kref_put(&lynx->kref, lynx_release);
}

struct client {
        struct pcilynx *lynx;
        u32 tcode_mask;
        struct packet_buffer buffer;
        struct list_head link;
};

static DEFINE_MUTEX(card_mutex);
static LIST_HEAD(card_list);

static int
packet_buffer_init(struct packet_buffer *buffer, size_t capacity)
{
        buffer->data = kmalloc(capacity, GFP_KERNEL);
        if (buffer->data == NULL)
                return -ENOMEM;
        buffer->head = (struct packet *) buffer->data;
        buffer->tail = (struct packet *) buffer->data;
        buffer->capacity = capacity;
        buffer->lost_packet_count = 0;
        atomic_set(&buffer->size, 0);
        init_waitqueue_head(&buffer->wait);

        return 0;
}

static void
packet_buffer_destroy(struct packet_buffer *buffer)
{
        kfree(buffer->data);
}

static int
packet_buffer_get(struct client *client, char __user *data, size_t user_length)
{
        struct packet_buffer *buffer = &client->buffer;
        size_t length;
        char *end;

        if (wait_event_interruptible(buffer->wait,
                                     atomic_read(&buffer->size) > 0) ||
                                     list_empty(&client->lynx->link))
                return -ERESTARTSYS;

        if (atomic_read(&buffer->size) == 0)
                return -ENODEV;

        length = buffer->head->length;

        if (length > user_length)
                return 0;

        end = buffer->data + buffer->capacity;

        if (&buffer->head->data[length] < end) {
                if (copy_to_user(data, buffer->head->data, length))
                        return -EFAULT;
                buffer->head = (struct packet *) &buffer->head->data[length];
        } else {
                size_t split = end - buffer->head->data;

                if (copy_to_user(data, buffer->head->data, split))
                        return -EFAULT;
                if (copy_to_user(data + split, buffer->data, length - split))
                        return -EFAULT;
                buffer->head = (struct packet *) &buffer->data[length - split];
        }

        /*
         * Decrease buffer->size as the last thing, since this is what
         * keeps the interrupt from overwriting the packet we are
         * retrieving from the buffer.
         */
        atomic_sub(sizeof(struct packet) + length, &buffer->size);

        return length;
}

static void
packet_buffer_put(struct packet_buffer *buffer, void *data, size_t length)
{
        char *end;

        buffer->total_packet_count++;

        if (buffer->capacity <
            atomic_read(&buffer->size) + sizeof(struct packet) + length) {
                buffer->lost_packet_count++;
                return;
        }

        end = buffer->data + buffer->capacity;
        buffer->tail->length = length;

        if (&buffer->tail->data[length] < end) {
                memcpy(buffer->tail->data, data, length);
                buffer->tail = (struct packet *) &buffer->tail->data[length];
        } else {
                size_t split = end - buffer->tail->data;

                memcpy(buffer->tail->data, data, split);
                memcpy(buffer->data, data + split, length - split);
                buffer->tail = (struct packet *) &buffer->data[length - split];
        }

        /* Finally, adjust buffer size and wake up userspace reader. */

        atomic_add(sizeof(struct packet) + length, &buffer->size);
        wake_up_interruptible(&buffer->wait);
}

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

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

static inline void
reg_set_bits(struct pcilynx *lynx, int offset, u32 mask)
{
        reg_write(lynx, offset, (reg_read(lynx, offset) | mask));
}

/*
 * Maybe the pcl programs could be set up to just append data instead
 * of using a whole packet.
 */
static inline void
run_pcl(struct pcilynx *lynx, dma_addr_t pcl_bus,
                           int dmachan)
{
        reg_write(lynx, DMA0_CURRENT_PCL + dmachan * 0x20, pcl_bus);
        reg_write(lynx, DMA0_CHAN_CTRL + dmachan * 0x20,
                  DMA_CHAN_CTRL_ENABLE | DMA_CHAN_CTRL_LINK);
}

static int
set_phy_reg(struct pcilynx *lynx, int addr, int val)
{
        if (addr > 15) {
                dev_err(&lynx->pci_device->dev,
                        "PHY register address %d out of range\n", addr);
                return -1;
        }
        if (val > 0xff) {
                dev_err(&lynx->pci_device->dev,
                        "PHY register value %d out of range\n", val);
                return -1;
        }
        reg_write(lynx, LINK_PHY, LINK_PHY_WRITE |
                  LINK_PHY_ADDR(addr) | LINK_PHY_WDATA(val));

        return 0;
}

static int
nosy_open(struct inode *inode, struct file *file)
{
        int minor = iminor(inode);
        struct client *client;
        struct pcilynx *tmp, *lynx = NULL;

        mutex_lock(&card_mutex);
        list_for_each_entry(tmp, &card_list, link)
                if (tmp->misc.minor == minor) {
                        lynx = lynx_get(tmp);
                        break;
                }
        mutex_unlock(&card_mutex);
        if (lynx == NULL)
                return -ENODEV;

        client = kmalloc_obj(*client);
        if (client == NULL)
                goto fail;

        client->tcode_mask = ~0;
        client->lynx = lynx;
        INIT_LIST_HEAD(&client->link);

        if (packet_buffer_init(&client->buffer, 128 * 1024) < 0)
                goto fail;

        file->private_data = client;

        return stream_open(inode, file);
fail:
        kfree(client);
        lynx_put(lynx);

        return -ENOMEM;
}

static int
nosy_release(struct inode *inode, struct file *file)
{
        struct client *client = file->private_data;
        struct pcilynx *lynx = client->lynx;

        spin_lock_irq(&lynx->client_list_lock);
        list_del_init(&client->link);
        spin_unlock_irq(&lynx->client_list_lock);

        packet_buffer_destroy(&client->buffer);
        kfree(client);
        lynx_put(lynx);

        return 0;
}

static __poll_t
nosy_poll(struct file *file, poll_table *pt)
{
        struct client *client = file->private_data;
        __poll_t ret = 0;

        poll_wait(file, &client->buffer.wait, pt);

        if (atomic_read(&client->buffer.size) > 0)
                ret = EPOLLIN | EPOLLRDNORM;

        if (list_empty(&client->lynx->link))
                ret |= EPOLLHUP;

        return ret;
}

static ssize_t
nosy_read(struct file *file, char __user *buffer, size_t count, loff_t *offset)
{
        struct client *client = file->private_data;

        return packet_buffer_get(client, buffer, count);
}

static long
nosy_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
        struct client *client = file->private_data;
        spinlock_t *client_list_lock = &client->lynx->client_list_lock;
        struct nosy_stats stats;
        int ret;

        switch (cmd) {
        case NOSY_IOC_GET_STATS:
                spin_lock_irq(client_list_lock);
                stats.total_packet_count = client->buffer.total_packet_count;
                stats.lost_packet_count  = client->buffer.lost_packet_count;
                spin_unlock_irq(client_list_lock);

                if (copy_to_user((void __user *) arg, &stats, sizeof stats))
                        return -EFAULT;
                else
                        return 0;

        case NOSY_IOC_START:
                ret = -EBUSY;
                spin_lock_irq(client_list_lock);
                if (list_empty(&client->link)) {
                        list_add_tail(&client->link, &client->lynx->client_list);
                        ret = 0;
                }
                spin_unlock_irq(client_list_lock);

                return ret;

        case NOSY_IOC_STOP:
                spin_lock_irq(client_list_lock);
                list_del_init(&client->link);
                spin_unlock_irq(client_list_lock);

                return 0;

        case NOSY_IOC_FILTER:
                spin_lock_irq(client_list_lock);
                client->tcode_mask = arg;
                spin_unlock_irq(client_list_lock);

                return 0;

        default:
                return -EINVAL;
                /* Flush buffer, configure filter. */
        }
}

static const struct file_operations nosy_ops = {
        .owner =                THIS_MODULE,
        .read =                 nosy_read,
        .unlocked_ioctl =       nosy_ioctl,
        .poll =                 nosy_poll,
        .open =                 nosy_open,
        .release =              nosy_release,
};

#define PHY_PACKET_SIZE 12 /* 1 payload, 1 inverse, 1 ack = 3 quadlets */

static void
packet_irq_handler(struct pcilynx *lynx)
{
        struct client *client;
        u32 tcode_mask, tcode, timestamp;
        size_t length;
        struct timespec64 ts64;

        /* FIXME: Also report rcv_speed. */

        length = __le32_to_cpu(lynx->rcv_pcl->pcl_status) & 0x00001fff;
        tcode  = __le32_to_cpu(lynx->rcv_buffer[1]) >> 4 & 0xf;

        ktime_get_real_ts64(&ts64);
        timestamp = ts64.tv_nsec / NSEC_PER_USEC;
        lynx->rcv_buffer[0] = (__force __le32)timestamp;

        if (length == PHY_PACKET_SIZE)
                tcode_mask = 1 << TCODE_PHY_PACKET;
        else
                tcode_mask = 1 << tcode;

        spin_lock(&lynx->client_list_lock);

        list_for_each_entry(client, &lynx->client_list, link)
                if (client->tcode_mask & tcode_mask)
                        packet_buffer_put(&client->buffer,
                                          lynx->rcv_buffer, length + 4);

        spin_unlock(&lynx->client_list_lock);
}

static void
bus_reset_irq_handler(struct pcilynx *lynx)
{
        struct client *client;
        struct timespec64 ts64;
        u32    timestamp;

        ktime_get_real_ts64(&ts64);
        timestamp = ts64.tv_nsec / NSEC_PER_USEC;

        spin_lock(&lynx->client_list_lock);

        list_for_each_entry(client, &lynx->client_list, link)
                packet_buffer_put(&client->buffer, &timestamp, 4);

        spin_unlock(&lynx->client_list_lock);
}

static irqreturn_t
irq_handler(int irq, void *device)
{
        struct pcilynx *lynx = device;
        u32 pci_int_status;

        pci_int_status = reg_read(lynx, PCI_INT_STATUS);

        if (pci_int_status == ~0)
                /* Card was ejected. */
                return IRQ_NONE;

        if ((pci_int_status & PCI_INT_INT_PEND) == 0)
                /* Not our interrupt, bail out quickly. */
                return IRQ_NONE;

        if ((pci_int_status & PCI_INT_P1394_INT) != 0) {
                u32 link_int_status;

                link_int_status = reg_read(lynx, LINK_INT_STATUS);
                reg_write(lynx, LINK_INT_STATUS, link_int_status);

                if ((link_int_status & LINK_INT_PHY_BUSRESET) > 0)
                        bus_reset_irq_handler(lynx);
        }

        /* Clear the PCI_INT_STATUS register only after clearing the
         * LINK_INT_STATUS register; otherwise the PCI_INT_P1394 will
         * be set again immediately. */

        reg_write(lynx, PCI_INT_STATUS, pci_int_status);

        if ((pci_int_status & PCI_INT_DMA0_HLT) > 0) {
                packet_irq_handler(lynx);
                run_pcl(lynx, lynx->rcv_start_pcl_bus, 0);
        }

        return IRQ_HANDLED;
}

static void
remove_card(struct pci_dev *dev)
{
        struct pcilynx *lynx = pci_get_drvdata(dev);
        struct client *client;

        mutex_lock(&card_mutex);
        list_del_init(&lynx->link);
        misc_deregister(&lynx->misc);
        mutex_unlock(&card_mutex);

        reg_write(lynx, PCI_INT_ENABLE, 0);
        free_irq(lynx->pci_device->irq, lynx);

        spin_lock_irq(&lynx->client_list_lock);
        list_for_each_entry(client, &lynx->client_list, link)
                wake_up_interruptible(&client->buffer.wait);
        spin_unlock_irq(&lynx->client_list_lock);

        dma_free_coherent(&lynx->pci_device->dev, sizeof(struct pcl),
                          lynx->rcv_start_pcl, lynx->rcv_start_pcl_bus);
        dma_free_coherent(&lynx->pci_device->dev, sizeof(struct pcl),
                          lynx->rcv_pcl, lynx->rcv_pcl_bus);
        dma_free_coherent(&lynx->pci_device->dev, RCV_BUFFER_SIZE,
                          lynx->rcv_buffer, lynx->rcv_buffer_bus);

        iounmap(lynx->registers);
        pci_disable_device(dev);
        lynx_put(lynx);
}

static int
add_card(struct pci_dev *dev, const struct pci_device_id *unused)
{
        struct pcilynx *lynx;
        u32 p, end;
        int ret, i;

        if (dma_set_mask(&dev->dev, DMA_BIT_MASK(32))) {
                dev_err(&dev->dev,
                    "DMA address limits not supported for PCILynx hardware\n");
                return -ENXIO;
        }
        if (pci_enable_device(dev)) {
                dev_err(&dev->dev, "Failed to enable PCILynx hardware\n");
                return -ENXIO;
        }
        pci_set_master(dev);

        lynx = kzalloc_obj(*lynx);
        if (lynx == NULL) {
                dev_err(&dev->dev, "Failed to allocate control structure\n");
                ret = -ENOMEM;
                goto fail_disable;
        }
        lynx->pci_device = dev;
        pci_set_drvdata(dev, lynx);

        spin_lock_init(&lynx->client_list_lock);
        INIT_LIST_HEAD(&lynx->client_list);
        kref_init(&lynx->kref);

        lynx->registers = ioremap(pci_resource_start(dev, 0),
                                          PCILYNX_MAX_REGISTER);
        if (lynx->registers == NULL) {
                dev_err(&dev->dev, "Failed to map registers\n");
                ret = -ENOMEM;
                goto fail_deallocate_lynx;
        }

        lynx->rcv_start_pcl = dma_alloc_coherent(&lynx->pci_device->dev,
                                                 sizeof(struct pcl),
                                                 &lynx->rcv_start_pcl_bus,
                                                 GFP_KERNEL);
        lynx->rcv_pcl = dma_alloc_coherent(&lynx->pci_device->dev,
                                           sizeof(struct pcl),
                                           &lynx->rcv_pcl_bus, GFP_KERNEL);
        lynx->rcv_buffer = dma_alloc_coherent(&lynx->pci_device->dev,
                                              RCV_BUFFER_SIZE,
                                              &lynx->rcv_buffer_bus, GFP_KERNEL);
        if (lynx->rcv_start_pcl == NULL ||
            lynx->rcv_pcl == NULL ||
            lynx->rcv_buffer == NULL) {
                dev_err(&dev->dev, "Failed to allocate receive buffer\n");
                ret = -ENOMEM;
                goto fail_deallocate_buffers;
        }
        lynx->rcv_start_pcl->next       = cpu_to_le32(lynx->rcv_pcl_bus);
        lynx->rcv_pcl->next             = cpu_to_le32(PCL_NEXT_INVALID);
        lynx->rcv_pcl->async_error_next = cpu_to_le32(PCL_NEXT_INVALID);

        lynx->rcv_pcl->buffer[0].control =
                        cpu_to_le32(PCL_CMD_RCV | PCL_BIGENDIAN | 2044);
        lynx->rcv_pcl->buffer[0].pointer =
                        cpu_to_le32(lynx->rcv_buffer_bus + 4);
        p = lynx->rcv_buffer_bus + 2048;
        end = lynx->rcv_buffer_bus + RCV_BUFFER_SIZE;
        for (i = 1; p < end; i++, p += 2048) {
                lynx->rcv_pcl->buffer[i].control =
                        cpu_to_le32(PCL_CMD_RCV | PCL_BIGENDIAN | 2048);
                lynx->rcv_pcl->buffer[i].pointer = cpu_to_le32(p);
        }
        lynx->rcv_pcl->buffer[i - 1].control |= cpu_to_le32(PCL_LAST_BUFF);

        reg_set_bits(lynx, MISC_CONTROL, MISC_CONTROL_SWRESET);
        /* Fix buggy cards with autoboot pin not tied low: */
        reg_write(lynx, DMA0_CHAN_CTRL, 0);
        reg_write(lynx, DMA_GLOBAL_REGISTER, 0x00 << 24);

#if 0
        /* now, looking for PHY register set */
        if ((get_phy_reg(lynx, 2) & 0xe0) == 0xe0) {
                lynx->phyic.reg_1394a = 1;
                PRINT(KERN_INFO, lynx->id,
                      "found 1394a conform PHY (using extended register set)");
                lynx->phyic.vendor = get_phy_vendorid(lynx);
                lynx->phyic.product = get_phy_productid(lynx);
        } else {
                lynx->phyic.reg_1394a = 0;
                PRINT(KERN_INFO, lynx->id, "found old 1394 PHY");
        }
#endif

        /* Setup the general receive FIFO max size. */
        reg_write(lynx, FIFO_SIZES, 255);

        reg_set_bits(lynx, PCI_INT_ENABLE, PCI_INT_DMA_ALL);

        reg_write(lynx, LINK_INT_ENABLE,
                  LINK_INT_PHY_TIME_OUT | LINK_INT_PHY_REG_RCVD |
                  LINK_INT_PHY_BUSRESET | LINK_INT_IT_STUCK |
                  LINK_INT_AT_STUCK | LINK_INT_SNTRJ |
                  LINK_INT_TC_ERR | LINK_INT_GRF_OVER_FLOW |
                  LINK_INT_ITF_UNDER_FLOW | LINK_INT_ATF_UNDER_FLOW);

        /* Disable the L flag in self ID packets. */
        set_phy_reg(lynx, 4, 0);

        /* Put this baby into snoop mode */
        reg_set_bits(lynx, LINK_CONTROL, LINK_CONTROL_SNOOP_ENABLE);

        run_pcl(lynx, lynx->rcv_start_pcl_bus, 0);

        if (request_irq(dev->irq, irq_handler, IRQF_SHARED,
                        driver_name, lynx)) {
                dev_err(&dev->dev,
                        "Failed to allocate shared interrupt %d\n", dev->irq);
                ret = -EIO;
                goto fail_deallocate_buffers;
        }

        lynx->misc.parent = &dev->dev;
        lynx->misc.minor = MISC_DYNAMIC_MINOR;
        lynx->misc.name = "nosy";
        lynx->misc.fops = &nosy_ops;

        mutex_lock(&card_mutex);
        ret = misc_register(&lynx->misc);
        if (ret) {
                dev_err(&dev->dev, "Failed to register misc char device\n");
                mutex_unlock(&card_mutex);
                goto fail_free_irq;
        }
        list_add_tail(&lynx->link, &card_list);
        mutex_unlock(&card_mutex);

        dev_info(&dev->dev,
                 "Initialized PCILynx IEEE1394 card, irq=%d\n", dev->irq);

        return 0;

fail_free_irq:
        reg_write(lynx, PCI_INT_ENABLE, 0);
        free_irq(lynx->pci_device->irq, lynx);

fail_deallocate_buffers:
        if (lynx->rcv_start_pcl)
                dma_free_coherent(&lynx->pci_device->dev, sizeof(struct pcl),
                                  lynx->rcv_start_pcl,
                                  lynx->rcv_start_pcl_bus);
        if (lynx->rcv_pcl)
                dma_free_coherent(&lynx->pci_device->dev, sizeof(struct pcl),
                                  lynx->rcv_pcl, lynx->rcv_pcl_bus);
        if (lynx->rcv_buffer)
                dma_free_coherent(&lynx->pci_device->dev, RCV_BUFFER_SIZE,
                                  lynx->rcv_buffer, lynx->rcv_buffer_bus);
        iounmap(lynx->registers);

fail_deallocate_lynx:
        kfree(lynx);

fail_disable:
        pci_disable_device(dev);

        return ret;
}

static struct pci_device_id pci_table[] = {
        {
                .vendor =    PCI_VENDOR_ID_TI,
                .device =    PCI_DEVICE_ID_TI_PCILYNX,
                .subvendor = PCI_ANY_ID,
                .subdevice = PCI_ANY_ID,
        },
        { }     /* Terminating entry */
};

MODULE_DEVICE_TABLE(pci, pci_table);

static struct pci_driver lynx_pci_driver = {
        .name =         driver_name,
        .id_table =     pci_table,
        .probe =        add_card,
        .remove =       remove_card,
};

module_pci_driver(lynx_pci_driver);

MODULE_AUTHOR("Kristian Hoegsberg");
MODULE_DESCRIPTION("Snoop mode driver for TI pcilynx 1394 controllers");
MODULE_LICENSE("GPL");