/*
 *  The PCI Library -- Direct Configuration access via RT-Thread Smart DM Ports
 *
 *  Copyright (c) 2024 RT-Thread Development Team
 *
 *  Can be freely distributed and used under the terms of the GNU GPL v2+.
 *
 *  SPDX-License-Identifier: GPL-2.0-or-later
 */

#include <ctype.h>
#include <errno.h>
#include <fcntl.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <stdint.h>

#include "internal.h"

static void
rt_thread_smart_dm_config(struct pci_access *a)
{
  pci_define_param(a, "rt-thread-smart-dm.path", PCI_PATH_RT_THREAD_SMART_DM,
    "Path to the RT-Thread Smart PCI device");
}

static int
rt_thread_smart_dm_detect(struct pci_access *a)
{
  char *name = pci_get_param(a, "rt-thread-smart-dm.path");

  if (access(name, R_OK))
    {
      a->warning("Cannot open %s", name);
      return 0;
    }

  a->debug("...using %s", name);
  return 1;
}

static void
rt_thread_smart_dm_init(struct pci_access *a)
{
  a->fd = -1;
}

static void
rt_thread_smart_dm_cleanup(struct pci_access *a UNUSED)
{
  if (a->fd >= 0)
    {
      close(a->fd);
      a->fd = -1;
    }
}

static void
rt_thread_smart_dm_scan(struct pci_access *a)
{
  FILE *f;
  char buf[512];

  if (snprintf(buf, sizeof(buf), "%s/devices", pci_get_param(a, "rt-thread-smart-dm.path")) == sizeof(buf))
    a->error("File name too long");

  f = fopen(buf, "r");
  if (!f)
    a->error("Cannot open %s", buf);

  while (fgets(buf, sizeof(buf)-1, f))
    {
      struct pci_dev *d = pci_alloc_dev(a);
      unsigned int dfn, vend, cnt, known;
      char *driver;
      int offset;

#define F " %016" PCI_U64_FMT_X
      cnt = sscanf(buf, "%x %x %x" F F F F F F F F F F F F F F "%n",
             &dfn,
             &vend,
             &d->irq,
             &d->base_addr[0],
             &d->base_addr[1],
             &d->base_addr[2],
             &d->base_addr[3],
             &d->base_addr[4],
             &d->base_addr[5],
             &d->rom_base_addr,
             &d->size[0],
             &d->size[1],
             &d->size[2],
             &d->size[3],
             &d->size[4],
             &d->size[5],
             &d->rom_size,
             &offset);
#undef F
      if (cnt != 9 && cnt != 10 && cnt != 17)
        a->error("proc: parse error (read only %d items)", cnt);
      d->bus = dfn >> 8U;
      d->dev = PCI_SLOT(dfn & 0xff);
      d->func = PCI_FUNC(dfn & 0xff);
      d->vendor_id = vend >> 16U;
      d->device_id = vend & 0xffff;
      known = 0;
      if (!a->buscentric)
        {
          known |= PCI_FILL_IDENT | PCI_FILL_IRQ | PCI_FILL_BASES;
          if (cnt >= 10)
            known |= PCI_FILL_ROM_BASE;
          if (cnt >= 17)
            known |= PCI_FILL_SIZES;
        }
      if (cnt >= 17)
        {
          while (buf[offset] && isspace(buf[offset]))
            ++offset;
          driver = &buf[offset];
          while (buf[offset] && !isspace(buf[offset]))
            ++offset;
          buf[offset] = '\0';
          if (driver[0])
            {
              pci_set_property(d, PCI_FILL_DRIVER, driver);
              known |= PCI_FILL_DRIVER;
            }
        }
      d->known_fields = known;
      pci_link_dev(a, d);
    }

  fclose(f);
}

static int
rt_thread_smart_dm_setup(struct pci_dev *d, int rw)
{
  struct pci_access *a = d->access;

  if (a->cached_dev != d || a->fd_rw < rw)
    {
      char buf[1024];
      int e;
      if (a->fd >= 0)
        close(a->fd);
      e = snprintf(buf, sizeof(buf), "%s/%04x:%02x:%02x.%u",
                   pci_get_param(a, "rt-thread-smart-dm.path"),
                   d->domain, d->bus, d->dev, d->func);
      if (e < 0 || e >= (int) sizeof(buf))
        a->error("File name too long");
      a->fd_rw = a->writeable || rw;
      a->fd = open(buf, a->fd_rw ? O_RDWR : O_RDONLY);
      if (a->fd < 0)
        a->warning("Cannot open %s", buf);
      a->cached_dev = d;
    }
  return a->fd;
}

static int
rt_thread_smart_dm_read(struct pci_dev *d, int pos, byte *buf, int len)
{
  int fd = rt_thread_smart_dm_setup(d, 0);
  int res;

  if (fd < 0)
    return 0;
  res = pread(fd, buf, len, pos);
  if (res < 0)
    {
      d->access->warning("%s: read failed: %s", __func__, strerror(errno));
      return 0;
    }
  else if (res != len)
    return 0;
  return 1;
}

static int
rt_thread_smart_dm_write(struct pci_dev *d, int pos, byte *buf, int len)
{
  int fd = rt_thread_smart_dm_setup(d, 1);
  int res;

  if (fd < 0)
    return 0;
  res = pwrite(fd, buf, len, pos);
  if (res < 0)
    {
      d->access->warning("%s: write failed: %s", __func__, strerror(errno));
      return 0;
    }
  else if (res != len)
    {
      d->access->warning("%s: tried to write %d bytes at %d, but only %d succeeded", __func__, len, pos, res);
      return 0;
    }
  return 1;
}

static void
rt_thread_smart_dm_cleanup_dev(struct pci_dev *d)
{
  if (d->access->cached_dev == d)
    d->access->cached_dev = NULL;
}

struct pci_methods pm_rt_thread_smart_dm = {
  .name = "rt-thread-smart-dm",
  .help = "RT-Thrad Smart /proc/pci device",
  .config = rt_thread_smart_dm_config,
  .detect = rt_thread_smart_dm_detect,
  .init = rt_thread_smart_dm_init,
  .cleanup = rt_thread_smart_dm_cleanup,
  .scan = rt_thread_smart_dm_scan,
  .fill_info = pci_generic_fill_info,
  .read = rt_thread_smart_dm_read,
  .write = rt_thread_smart_dm_write,
  .cleanup_dev = rt_thread_smart_dm_cleanup_dev,
};