/* scsi.c - scsi support.  */
/*
 *  GRUB  --  GRand Unified Bootloader
 *  Copyright (C) 2008,2009  Free Software Foundation, Inc.
 *
 *  GRUB is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation, either version 3 of the License, or
 *  (at your option) any later version.
 *
 *  GRUB is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with GRUB.  If not, see <http://www.gnu.org/licenses/>.
 */

#include <grub/disk.h>
#include <grub/dl.h>
#include <grub/kernel.h>
#include <grub/misc.h>
#include <grub/mm.h>
#include <grub/types.h>
#include <grub/scsi.h>
#include <grub/scsicmd.h>
#include <grub/time.h>

GRUB_MOD_LICENSE ("GPLv3+");


static grub_scsi_dev_t grub_scsi_dev_list;

const char grub_scsi_names[GRUB_SCSI_NUM_SUBSYSTEMS][5] = {
  [GRUB_SCSI_SUBSYSTEM_USBMS] = "usb",
  [GRUB_SCSI_SUBSYSTEM_PATA] = "ata",
  [GRUB_SCSI_SUBSYSTEM_AHCI] = "ahci"
};

void
grub_scsi_dev_register (grub_scsi_dev_t dev)
{
  dev->next = grub_scsi_dev_list;
  grub_scsi_dev_list = dev;
}

void
grub_scsi_dev_unregister (grub_scsi_dev_t dev)
{
  grub_scsi_dev_t *p, q;

  for (p = &grub_scsi_dev_list, q = *p; q; p = &(q->next), q = q->next)
    if (q == dev)
      {
        *p = q->next;
	break;
      }
}


/* Check result of previous operation.  */
static grub_err_t
grub_scsi_request_sense (grub_scsi_t scsi)
{
  struct grub_scsi_request_sense rs;
  struct grub_scsi_request_sense_data rsd;
  grub_err_t err;

  rs.opcode = grub_scsi_cmd_request_sense;
  rs.lun = scsi->lun << GRUB_SCSI_LUN_SHIFT;
  rs.reserved1 = 0;
  rs.reserved2 = 0;
  rs.alloc_length = 0x12; /* XXX: Hardcoded for now */
  rs.control = 0;
  grub_memset (rs.pad, 0, sizeof(rs.pad));

  err = scsi->dev->read (scsi, sizeof (rs), (char *) &rs,
			 sizeof (rsd), (char *) &rsd);
  if (err)
    return err;

  return GRUB_ERR_NONE;
}
/* Self commenting... */
static grub_err_t
grub_scsi_test_unit_ready (grub_scsi_t scsi)
{
  struct grub_scsi_test_unit_ready tur;
  grub_err_t err;
  grub_err_t err_sense;
  
  tur.opcode = grub_scsi_cmd_test_unit_ready;
  tur.lun = scsi->lun << GRUB_SCSI_LUN_SHIFT;
  tur.reserved1 = 0;
  tur.reserved2 = 0;
  tur.reserved3 = 0;
  tur.control = 0;
  grub_memset (tur.pad, 0, sizeof(tur.pad));

  err = scsi->dev->read (scsi, sizeof (tur), (char *) &tur,
			 0, NULL);

  /* Each SCSI command should be followed by Request Sense.
     If not so, many devices STALLs or definitely freezes. */
  err_sense = grub_scsi_request_sense (scsi);
  if (err_sense != GRUB_ERR_NONE)
  	grub_errno = err;
  /* err_sense is ignored for now and Request Sense Data also... */
  
  if (err)
    return err;

  return GRUB_ERR_NONE;
}

/* Determine if the device is removable and the type of the device
   SCSI.  */
static grub_err_t
grub_scsi_inquiry (grub_scsi_t scsi)
{
  struct grub_scsi_inquiry iq;
  struct grub_scsi_inquiry_data iqd;
  grub_err_t err;
  grub_err_t err_sense;

  iq.opcode = grub_scsi_cmd_inquiry;
  iq.lun = scsi->lun << GRUB_SCSI_LUN_SHIFT;
  iq.page = 0;
  iq.reserved = 0;
  iq.alloc_length = 0x24; /* XXX: Hardcoded for now */
  iq.control = 0;
  grub_memset (iq.pad, 0, sizeof(iq.pad));

  err = scsi->dev->read (scsi, sizeof (iq), (char *) &iq,
			 sizeof (iqd), (char *) &iqd);

  /* Each SCSI command should be followed by Request Sense.
     If not so, many devices STALLs or definitely freezes. */
  err_sense = grub_scsi_request_sense (scsi);
  if (err_sense != GRUB_ERR_NONE)
  	grub_errno = err;
  /* err_sense is ignored for now and Request Sense Data also... */

  if (err)
    return err;

  scsi->devtype = iqd.devtype & GRUB_SCSI_DEVTYPE_MASK;
  scsi->removable = iqd.rmb >> GRUB_SCSI_REMOVABLE_BIT;

  return GRUB_ERR_NONE;
}

/* Read the capacity and block size of SCSI.  */
static grub_err_t
grub_scsi_read_capacity (grub_scsi_t scsi)
{
  struct grub_scsi_read_capacity rc;
  struct grub_scsi_read_capacity_data rcd;
  grub_err_t err;
  grub_err_t err_sense;

  rc.opcode = grub_scsi_cmd_read_capacity;
  rc.lun = scsi->lun << GRUB_SCSI_LUN_SHIFT;
  rc.logical_block_addr = 0;
  rc.reserved1 = 0;
  rc.reserved2 = 0;
  rc.PMI = 0;
  rc.control = 0;
  rc.pad = 0;
	
  err = scsi->dev->read (scsi, sizeof (rc), (char *) &rc,
			 sizeof (rcd), (char *) &rcd);

  /* Each SCSI command should be followed by Request Sense.
     If not so, many devices STALLs or definitely freezes. */
  err_sense = grub_scsi_request_sense (scsi);
  if (err_sense != GRUB_ERR_NONE)
  	grub_errno = err;
/* err_sense is ignored for now and Request Sense Data also... */

  if (err)
    return err;

  scsi->size = grub_be_to_cpu32 (rcd.size);
  scsi->blocksize = grub_be_to_cpu32 (rcd.blocksize);

  return GRUB_ERR_NONE;
}

/* Send a SCSI request for DISK: read SIZE sectors starting with
   sector SECTOR to BUF.  */
static grub_err_t
grub_scsi_read10 (grub_disk_t disk, grub_disk_addr_t sector,
		  grub_size_t size, char *buf)
{
  grub_scsi_t scsi;
  struct grub_scsi_read10 rd;
  grub_err_t err;
  grub_err_t err_sense;

  scsi = disk->data;

  rd.opcode = grub_scsi_cmd_read10;
  rd.lun = scsi->lun << GRUB_SCSI_LUN_SHIFT;
  rd.lba = grub_cpu_to_be32 (sector);
  rd.reserved = 0;
  rd.size = grub_cpu_to_be16 (size);
  rd.reserved2 = 0;
  rd.pad = 0;

  err = scsi->dev->read (scsi, sizeof (rd), (char *) &rd, size * scsi->blocksize, buf);

  /* Each SCSI command should be followed by Request Sense.
     If not so, many devices STALLs or definitely freezes. */
  err_sense = grub_scsi_request_sense (scsi);
  if (err_sense != GRUB_ERR_NONE)
  	grub_errno = err;
  /* err_sense is ignored for now and Request Sense Data also... */

  return err;
}

/* Send a SCSI request for DISK: read SIZE sectors starting with
   sector SECTOR to BUF.  */
static grub_err_t
grub_scsi_read12 (grub_disk_t disk, grub_disk_addr_t sector,
		  grub_size_t size, char *buf)
{
  grub_scsi_t scsi;
  struct grub_scsi_read12 rd;
  grub_err_t err;
  grub_err_t err_sense;

  scsi = disk->data;

  rd.opcode = grub_scsi_cmd_read12;
  rd.lun = scsi->lun << GRUB_SCSI_LUN_SHIFT;
  rd.lba = grub_cpu_to_be32 (sector);
  rd.size = grub_cpu_to_be32 (size);
  rd.reserved = 0;
  rd.control = 0;

  err = scsi->dev->read (scsi, sizeof (rd), (char *) &rd, size * scsi->blocksize, buf);

  /* Each SCSI command should be followed by Request Sense.
     If not so, many devices STALLs or definitely freezes. */
  err_sense = grub_scsi_request_sense (scsi);
  if (err_sense != GRUB_ERR_NONE)
  	grub_errno = err;
  /* err_sense is ignored for now and Request Sense Data also... */

  return err;
}

#if 0
/* Send a SCSI request for DISK: write the data stored in BUF to SIZE
   sectors starting with SECTOR.  */
static grub_err_t
grub_scsi_write10 (grub_disk_t disk, grub_disk_addr_t sector,
		   grub_size_t size, char *buf)
{
  grub_scsi_t scsi;
  struct grub_scsi_write10 wr;
  grub_err_t err;
  grub_err_t err_sense;

  scsi = disk->data;

  wr.opcode = grub_scsi_cmd_write10;
  wr.lun = scsi->lun << GRUB_SCSI_LUN_SHIFT;
  wr.lba = grub_cpu_to_be32 (sector);
  wr.reserved = 0;
  wr.size = grub_cpu_to_be16 (size);
  wr.reserved2 = 0;
  wr.pad = 0;

  err = scsi->dev->write (scsi, sizeof (wr), (char *) &wr, size * scsi->blocksize, buf);

  /* Each SCSI command should be followed by Request Sense.
     If not so, many devices STALLs or definitely freezes. */
  err_sense = grub_scsi_request_sense (scsi);
  if (err_sense != GRUB_ERR_NONE)
  	grub_errno = err;
  /* err_sense is ignored for now and Request Sense Data also... */

  return err;
}

/* Send a SCSI request for DISK: write the data stored in BUF to SIZE
   sectors starting with SECTOR.  */
static grub_err_t
grub_scsi_write12 (grub_disk_t disk, grub_disk_addr_t sector,
		   grub_size_t size, char *buf)
{
  grub_scsi_t scsi;
  struct grub_scsi_write12 wr;
  grub_err_t err;
  grub_err_t err_sense;

  scsi = disk->data;

  wr.opcode = grub_scsi_cmd_write12;
  wr.lun = scsi->lun << GRUB_SCSI_LUN_SHIFT;
  wr.lba = grub_cpu_to_be32 (sector);
  wr.size = grub_cpu_to_be32 (size);
  wr.reserved = 0;
  wr.control = 0;

  err = scsi->dev->write (scsi, sizeof (wr), (char *) &wr, size * scsi->blocksize, buf);

  /* Each SCSI command should be followed by Request Sense.
     If not so, many devices STALLs or definitely freezes. */
  err_sense = grub_scsi_request_sense (scsi);
  if (err_sense != GRUB_ERR_NONE)
  	grub_errno = err;
  /* err_sense is ignored for now and Request Sense Data also... */

  return err;
}
#endif


static int
grub_scsi_iterate (int (*hook) (const char *name),
		   grub_disk_pull_t pull)
{
  grub_scsi_dev_t p;

  auto int NESTED_FUNC_ATTR scsi_iterate (int id, int bus, int luns);

  int NESTED_FUNC_ATTR scsi_iterate (int id, int bus, int luns)
    {
      int i;

      /* In case of a single LUN, just return `usbX'.  */
      if (luns == 1)
	{
	  char *sname;
	  int ret;
	  sname = grub_xasprintf ("%s%d", grub_scsi_names[id], bus);
	  if (!sname)
	    return 1;
	  ret = hook (sname);
	  grub_free (sname);
	  return ret;
	}

      /* In case of multiple LUNs, every LUN will get a prefix to
	 distinguish it.  */
      for (i = 0; i < luns; i++)
	{
	  char *sname;
	  int ret;
	  sname = grub_xasprintf ("%s%d%c", grub_scsi_names[id], bus, 'a' + i);
	  if (!sname)
	    return 1;
	  ret = hook (sname);
	  grub_free (sname);
	  if (ret)
	    return 1;
	}
      return 0;
    }

  for (p = grub_scsi_dev_list; p; p = p->next)
    if (p->iterate && (p->iterate) (scsi_iterate, pull))
      return 1;

  return 0;
}

static grub_err_t
grub_scsi_open (const char *name, grub_disk_t disk)
{
  grub_scsi_dev_t p;
  grub_scsi_t scsi;
  grub_err_t err;
  int lun, bus;
  grub_uint64_t maxtime;
  const char *nameend;
  unsigned id;

  nameend = name + grub_strlen (name) - 1;
  /* Try to detect a LUN ('a'-'z'), otherwise just use the first
     LUN.  */
  if (nameend >= name && *nameend >= 'a' && *nameend <= 'z')
    {
      lun = *nameend - 'a';
      nameend--;
    }
  else
    lun = 0;

  while (nameend >= name && grub_isdigit (*nameend))
    nameend--;

  if (!nameend[1] || !grub_isdigit (nameend[1]))
    return grub_error (GRUB_ERR_UNKNOWN_DEVICE, "not a SCSI disk");

  bus = grub_strtoul (nameend + 1, 0, 0);

  scsi = grub_malloc (sizeof (*scsi));
  if (! scsi)
    return grub_errno;

  for (id = 0; id < ARRAY_SIZE (grub_scsi_names); id++)
    if (grub_strncmp (grub_scsi_names[id], name, nameend - name) == 0)
      break;

  if (id == ARRAY_SIZE (grub_scsi_names))
    {
      grub_free (scsi);
      return grub_error (GRUB_ERR_UNKNOWN_DEVICE, "not a SCSI disk");
    }

  for (p = grub_scsi_dev_list; p; p = p->next)
    {
      if (p->open (id, bus, scsi))
	{
	  grub_errno = GRUB_ERR_NONE;
	  continue;
	}

      disk->id = grub_make_scsi_id (id, bus, lun);
      disk->data = scsi;
      scsi->dev = p;
      scsi->lun = lun;
      scsi->bus = bus;

      grub_dprintf ("scsi", "dev opened\n");

      err = grub_scsi_inquiry (scsi);
      if (err)
	{
	  grub_free (scsi);
	  grub_dprintf ("scsi", "inquiry failed\n");
	  return err;
	}

      grub_dprintf ("scsi", "inquiry: devtype=0x%02x removable=%d\n",
		    scsi->devtype, scsi->removable);

      /* Try to be conservative about the device types
	 supported.  */
      if (scsi->devtype != grub_scsi_devtype_direct
	  && scsi->devtype != grub_scsi_devtype_cdrom)
	{
	  grub_free (scsi);
	  return grub_error (GRUB_ERR_UNKNOWN_DEVICE,
			     "unknown SCSI device");
	}

      /* According to USB MS tests specification, issue Test Unit Ready
       * until OK */
      maxtime = grub_get_time_ms () + 5000; /* It is safer value */
      do
        {
	  /* Timeout is necessary - for example in case when we have
	   * universal card reader with more LUNs and we have only
	   * one card inserted (or none), so only one LUN (or none)
	   * will be ready - and we want not to hang... */
	  if (grub_get_time_ms () > maxtime)
            {
              err = GRUB_ERR_READ_ERROR;
              grub_free (scsi);
              grub_dprintf ("scsi", "LUN is not ready - timeout\n");
              return err;
            }
          err = grub_scsi_test_unit_ready (scsi);
        }
      while (err == GRUB_ERR_READ_ERROR);
      /* Reset grub_errno !
       * It is set to some error code in loop before... */
      grub_errno = GRUB_ERR_NONE;

      /* Read capacity of media */
      err = grub_scsi_read_capacity (scsi);
      if (err)
	{
	  grub_free (scsi);
	  grub_dprintf ("scsi", "READ CAPACITY failed\n");
	  return err;
	}

      disk->total_sectors = scsi->size;
      if (scsi->blocksize & (scsi->blocksize - 1) || !scsi->blocksize)
	{
	  grub_free (scsi);
	  return grub_error (GRUB_ERR_IO, "invalid sector size %d",
			     scsi->blocksize);
	}
      for (disk->log_sector_size = 0;
	   (1 << disk->log_sector_size) < scsi->blocksize;
	   disk->log_sector_size++);

      grub_dprintf ("scsi", "blocks=%u, blocksize=%u\n",
		    scsi->size, scsi->blocksize);
      grub_dprintf ("scsi", "Disk total sectors = %llu\n",
		    (unsigned long long) disk->total_sectors);

      return GRUB_ERR_NONE;
    }

  grub_free (scsi);
  return grub_error (GRUB_ERR_UNKNOWN_DEVICE, "not a SCSI disk");
}

static void
grub_scsi_close (grub_disk_t disk)
{
  grub_scsi_t scsi;

  scsi = disk->data;
  if (scsi->dev->close)
    scsi->dev->close (scsi);
  grub_free (scsi);
}

static grub_err_t
grub_scsi_read (grub_disk_t disk, grub_disk_addr_t sector,
		grub_size_t size, char *buf)
{
  grub_scsi_t scsi;

  scsi = disk->data;

  while (size)
    {
      /* PATA doesn't support more than 32K reads.
	 Not sure about AHCI and USB. If it's confirmed that either of
	 them can do bigger reads reliably this value can be moved to 'scsi'
	 structure.  */
      grub_size_t len = 32768 >> disk->log_sector_size;
      grub_err_t err;
      if (len > size)
	len = size;
      /* Depending on the type, select a read function.  */
      switch (scsi->devtype)
	{
	case grub_scsi_devtype_direct:
	  err = grub_scsi_read10 (disk, sector, len, buf);
	  if (err)
	    return err;
	  break;

	case grub_scsi_devtype_cdrom:
	  err = grub_scsi_read12 (disk, sector, len, buf);
	  if (err)
	    return err;
	  break;
	}
      size -= len;
      sector += len;
      buf += len << disk->log_sector_size;
    }

  return GRUB_ERR_NONE;

#if 0 /* Workaround - it works - but very slowly, from some reason
       * unknown to me (specially on OHCI). Do not use it. */
  /* Split transfer requests to device sector size because */
  /* some devices are not able to transfer more than 512-1024 bytes */
  grub_err_t err = GRUB_ERR_NONE;

  for ( ; size; size--)
    {
      /* Depending on the type, select a read function.  */
      switch (scsi->devtype)
        {
          case grub_scsi_devtype_direct:
            err = grub_scsi_read10 (disk, sector, 1, buf);
            break;

          case grub_scsi_devtype_cdrom:
            err = grub_scsi_read12 (disk, sector, 1, buf);
            break;

          default: /* This should not happen */
            return GRUB_ERR_READ_ERROR;
        }
      if (err)
        return err;
      sector++;
      buf += scsi->blocksize;
    }

  return err;
#endif
}

static grub_err_t
grub_scsi_write (grub_disk_t disk __attribute((unused)),
		 grub_disk_addr_t sector __attribute((unused)),
		 grub_size_t size __attribute((unused)),
		 const char *buf __attribute((unused)))
{
#if 0
  /* XXX: Not tested yet!  */

  /* XXX: This should depend on the device type?  */
  return grub_scsi_write10 (disk, sector, size, buf);
#endif
  return GRUB_ERR_NOT_IMPLEMENTED_YET;
}


static struct grub_disk_dev grub_scsi_dev =
  {
    .name = "scsi",
    .id = GRUB_DISK_DEVICE_SCSI_ID,
    .iterate = grub_scsi_iterate,
    .open = grub_scsi_open,
    .close = grub_scsi_close,
    .read = grub_scsi_read,
    .write = grub_scsi_write,
    .next = 0
  };

GRUB_MOD_INIT(scsi)
{
  grub_disk_dev_register (&grub_scsi_dev);
}

GRUB_MOD_FINI(scsi)
{
  grub_disk_dev_unregister (&grub_scsi_dev);
}
