incubator-nuttx/drivers/bch/bchdev_driver.c

/****************************************************************************
 * drivers/bch/bchdev_driver.c
 *
 *   Copyright (C) 2008-2009, 2014-2015 Gregory Nutt. All rights reserved.
 *   Author: Gregory Nutt <gnutt@nuttx.org>
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 * 3. Neither the name NuttX nor the names of its contributors may be
 *    used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 *
 ****************************************************************************/

/****************************************************************************
 * Compilation Switches
 ****************************************************************************/

/****************************************************************************
 * Included Files
 ****************************************************************************/

#include <nuttx/config.h>

#include <sys/types.h>
#include <sys/stat.h>
#include <sys/ioctl.h>

#include <unistd.h>
#include <string.h>
#include <fcntl.h>
#include <sched.h>
#include <errno.h>
#include <assert.h>
#include <debug.h>

#include <nuttx/fs/fs.h>
#include <nuttx/fs/ioctl.h>

#include "bch.h"

/****************************************************************************
 * Pre-processor Definitions
 ****************************************************************************/

/****************************************************************************
 * Private Function Prototypes
 ****************************************************************************/

static int     bch_open(FAR struct file *filep);
static int     bch_close(FAR struct file *filep);
static off_t   bch_seek(FAR struct file *filep, off_t offset, int whence);
static ssize_t bch_read(FAR struct file *filep, FAR char *buffer,
                 size_t buflen);
static ssize_t bch_write(FAR struct file *filep, FAR const char *buffer,
                 size_t buflen);
static int     bch_ioctl(FAR struct file *filep, int cmd,
                 unsigned long arg);
#ifndef CONFIG_DISABLE_PSEUDOFS_OPERATIONS
static int     bch_unlink(FAR struct inode *inode);
#endif

/****************************************************************************
 * Public Data
 ****************************************************************************/

const struct file_operations bch_fops =
{
  bch_open,    /* open */
  bch_close,   /* close */
  bch_read,    /* read */
  bch_write,   /* write */
  bch_seek,    /* seek */
  bch_ioctl    /* ioctl */
#ifndef CONFIG_DISABLE_POLL
  , 0          /* poll */
#endif
#ifndef CONFIG_DISABLE_PSEUDOFS_OPERATIONS
  , bch_unlink /* unlink */
#endif
};

/****************************************************************************
 * Private Functions
 ****************************************************************************/

/****************************************************************************
 * Name: bch_open
 *
 * Description: Open the block device
 *
 ****************************************************************************/

static int bch_open(FAR struct file *filep)
{
  FAR struct inode *inode = filep->f_inode;
  FAR struct bchlib_s *bch;

  DEBUGASSERT(inode && inode->i_private);
  bch = (FAR struct bchlib_s *)inode->i_private;

  /* Increment the reference count */

  bchlib_semtake(bch);
  if (bch->refs == MAX_OPENCNT)
    {
      return -EMFILE;
    }
  else
    {
      bch->refs++;
    }

  bchlib_semgive(bch);
  return OK;
}

/****************************************************************************
 * Name: bch_close
 *
 * Description: close the block device
 *
 ****************************************************************************/

static int bch_close(FAR struct file *filep)
{
  FAR struct inode *inode = filep->f_inode;
  FAR struct bchlib_s *bch;
  int ret = OK;

  DEBUGASSERT(inode && inode->i_private);
  bch = (FAR struct bchlib_s *)inode->i_private;

  /* Flush any dirty pages remaining in the cache */

  bchlib_semtake(bch);
  (void)bchlib_flushsector(bch);

  /* Decrement the reference count (I don't use bchlib_decref() because I
   * want the entire close operation to be atomic wrt other driver
   * operations.
   */

  if (bch->refs == 0)
    {
      ret = -EIO;
    }
  else
    {
      bch->refs--;

      /* If the reference count decremented to zero AND if the character
       * driver has been unlinked, then teardown the BCH device now.
       */

      if (bch->refs == 0 && bch->unlinked)
        {
           /* Tear the driver down now. */

           ret = bchlib_teardown((FAR void *)bch);

           /* bchlib_teardown() would only fail if there are outstanding
            * references on the device.  Since we know that is not true, it
            * should not fail at all.
            */

           DEBUGASSERT(ret >= 0);
           if (ret >= 0)
             {
                /* Return without releasing the stale semaphore */

                return OK;
             }
        }
    }

  bchlib_semgive(bch);
  return ret;
}

/****************************************************************************
 * Name: bch_seek
 ****************************************************************************/

static off_t bch_seek(FAR struct file *filep, off_t offset, int whence)
{
  FAR struct inode *inode = filep->f_inode;
  FAR struct bchlib_s *bch;
  off_t newpos;
  int ret;

  DEBUGASSERT(inode && inode->i_private);

  bch = (FAR struct bchlib_s *)inode->i_private;
  bchlib_semtake(bch);

  /* Determine the new, requested file position */

  switch (whence)
    {
    case SEEK_CUR:
      newpos = filep->f_pos + offset;
      break;

    case SEEK_SET:
      newpos = offset;
      break;

    case SEEK_END:
      newpos = bch->sectsize * bch->nsectors + offset;
      break;

    default:
      /* Return EINVAL if the whence argument is invalid */

      bchlib_semgive(bch);
      return -EINVAL;
    }

  /* Opengroup.org:
   *
   *  "The lseek() function shall allow the file offset to be set beyond the end
   *   of the existing data in the file. If data is later written at this point,
   *   subsequent reads of data in the gap shall return bytes with the value 0
   *   until data is actually written into the gap."
   *
   * We can conform to the first part, but not the second.  But return EINVAL if
   *
   *  "...the resulting file offset would be negative for a regular file, block
   *   special file, or directory."
   */

  if (newpos >= 0)
    {
      filep->f_pos = newpos;
      ret = newpos;
    }
  else
    {
      ret = -EINVAL;
    }

  bchlib_semgive(bch);
  return ret;
}

/****************************************************************************
 * Name: bch_read
 ****************************************************************************/

static ssize_t bch_read(FAR struct file *filep, FAR char *buffer, size_t len)
{
  FAR struct inode *inode = filep->f_inode;
  FAR struct bchlib_s *bch;
  int ret;

  DEBUGASSERT(inode && inode->i_private);
  bch = (FAR struct bchlib_s *)inode->i_private;

  bchlib_semtake(bch);
  ret = bchlib_read(bch, buffer, filep->f_pos, len);
  if (ret > 0)
    {
      filep->f_pos += len;
    }

  bchlib_semgive(bch);
  return ret;
}

/****************************************************************************
 * Name:bch_write
 ****************************************************************************/

static ssize_t bch_write(FAR struct file *filep, FAR const char *buffer, size_t len)
{
  FAR struct inode *inode = filep->f_inode;
  FAR struct bchlib_s *bch;
  int ret = -EACCES;

  DEBUGASSERT(inode && inode->i_private);
  bch = (FAR struct bchlib_s *)inode->i_private;

  if (!bch->readonly)
    {
      bchlib_semtake(bch);
      ret = bchlib_write(bch, buffer, filep->f_pos, len);
      if (ret > 0)
        {
          filep->f_pos += len;
        }

      bchlib_semgive(bch);
    }

  return ret;
}

/****************************************************************************
 * Name: bch_ioctl
 *
 * Description: Return device geometry
 *
 ****************************************************************************/

static int bch_ioctl(FAR struct file *filep, int cmd, unsigned long arg)
{
  FAR struct inode *inode = filep->f_inode;
  FAR struct bchlib_s *bch;
  int ret = -ENOTTY;

  DEBUGASSERT(inode && inode->i_private);
  bch = (FAR struct bchlib_s *)inode->i_private;

  /* Is this a request to get the private data structure */

  if (cmd == DIOC_GETPRIV)
    {
      FAR struct bchlib_s **bchr = (FAR struct bchlib_s **)((uintptr_t)arg);

      bchlib_semtake(bch);
      if (!bchr || bch->refs == MAX_OPENCNT)
        {
          ret = -EINVAL;
        }
      else
        {
          bch->refs++;
          *bchr = bch;
        }

      bchlib_semgive(bch);
    }

#ifdef CONFIG_BCH_ENCRYPTION
  /* Is this a request to set the encryption key? */

  else if (cmd == DIOC_SETKEY)
    {
      memcpy(bch->key, (FAR void *)arg, CONFIG_BCH_ENCRYPTION_KEY_SIZE);
      ret = OK;
    }
#endif

  /* Otherwise, pass the IOCTL command on to the contained block driver */

  else
    {
      FAR struct inode *bchinode = bch->inode;

      /* Does the block driver support the ioctl method? */

      if (bchinode->u.i_bops->ioctl != NULL)
        {
          ret = bchinode->u.i_bops->ioctl(bchinode, cmd, arg);
        }
    }

  return ret;
}

/****************************************************************************
 * Name: bch_unlink
 *
 * Handle unlinking of the BCH device
 *
 ****************************************************************************/

#ifndef CONFIG_DISABLE_PSEUDOFS_OPERATIONS
static int bch_unlink(FAR struct inode *inode)
{
  FAR struct bchlib_s *bch;
  int ret = OK;

  DEBUGASSERT(inode && inode->i_private);
  bch = (FAR struct bchlib_s *)inode->i_private;

  /* Get exclusive access to the BCH device */

  bchlib_semtake(bch);

  /* Indicate that the driver has been unlinked */

  bch->unlinked = true;

  /* If there are no open references to the drvier then teardown the BCH
   * device now.
   */

  if (bch->refs == 0)
    {
      /* Tear the driver down now. */

      ret = bchlib_teardown((FAR void *)bch);

      /* bchlib_teardown() would only fail if there are outstanding
       * references on the device.  Since we know that is not true, it
       * should not fail at all.
       */

      DEBUGASSERT(ret >= 0);
      if (ret >= 0)
        {
          /* Return without releasing the stale semaphore */

          return OK;
        }
    }

  bchlib_semgive(bch);
  return ret;
}
#endif

/****************************************************************************
 * Public Functions
 ****************************************************************************/