source: rtems/cpukit/libblock/include/rtems/diskdevs.h @ d8602eb

/**
 * @file
 *
 * Block device disk management.
 */
 
/*
 * Copyright (C) 2001 OKTET Ltd., St.-Petersburg, Russia
 * Author: Victor V. Vengerov <vvv@oktet.ru>
 *
 * @(#) $Id$
 */

#ifndef _RTEMS_DISKDEVS_H
#define _RTEMS_DISKDEVS_H

#include <rtems.h>
#include <rtems/libio.h>
#include <stdlib.h>

/**
 * @ingroup rtems_bdbuf
 *
 * Buffer pool identifier.
 */
typedef int rtems_bdpool_id;

#include <rtems/blkdev.h>

#ifdef __cplusplus
extern "C" {
#endif

/**
 * @defgroup rtems_disk Block Device Disk Management
 *
 * @ingroup rtems_libblock
 *
 * This module provides functions to manage disk devices.
 *
 * A disk is a set of blocks which are identified by a consecutive set of
 * non-negative integers starting at zero.  There are also logical disks which
 * contain a subset of consecutive disk blocks.  The logical disks are used to
 * represent the partitions of a disk.  The disk devices are accessed via the
 * @ref rtems_bdbuf "block device buffer module". 
 *
 * @{
 */

/**
 * Block device IO control handler type.
 */
typedef int (*rtems_block_device_ioctl)( dev_t dev, uint32_t req, void *argp);

/**
 * Description of a disk device (logical and physical disks).
 *
 * An array of pointer tables to rtems_disk_device structures is maintained.
 * The first table will be indexed by the major number and the second table
 * will be indexed by the minor number.  This allows quick lookup using a data
 * structure of moderated size.
 */
typedef struct rtems_disk_device {
  /**
   * Device identifier (concatenation of major and minor number).
   */
  dev_t dev;

  /**
   * Physical device identifier (equals the @c dev entry if it specifies a
   * physical device).
   */
  struct rtems_disk_device *phys_dev;

  /**
   * Driver capabilities.
   */
  uint32_t capabilities;

  /**
   * Disk device name.
   */
  char *name;

  /**
   * Usage counter.
   *
   * Devices cannot be removed if they are in use.
   */
  unsigned uses;

  /**
   * Start block number.
   *
   * Equals zero for physical devices.  It is a block offset to the related
   * physical device for logical device.
   */
  rtems_blkdev_bnum start;

  /**
   * Size of the physical or logical disk in blocks.
   */
  rtems_blkdev_bnum size;

  /**
   * Device block size in bytes.
   *
   * This is the minimum transfer unit and must be power of two.
   */
  uint32_t block_size;

  /**
   * Binary logarithm of the block size.
   */
  uint32_t block_size_log2;

  /**
   * Buffer pool assigned to this disk.
   */
  rtems_bdpool_id pool;

  /**
   * IO control handler for this disk.
   */
  rtems_block_device_ioctl ioctl;
} rtems_disk_device;

/**
 * Creates a physical disk with device identifier @a dev.
 *
 * The block size @a block_size must be a power of two.  The disk size @a
 * disk_size is the number of blocks provided by this disk.  The block index
 * starts with zero.  The associated disk device driver will be invoked via the
 * IO control handler @a handler.  A device node will be registered in the file
 * system with absolute path @a name.  This function is usually invoked from a
 * block device driver during initialization when a physical device is detected
 * in the system.  The device driver provides an IO control handler to allow
 * block device operations.
 */
rtems_status_code rtems_disk_create_phys(
  dev_t dev,
  uint32_t block_size,
  rtems_blkdev_bnum disk_size,
  rtems_block_device_ioctl handler,
  const char *name
);

/**
 * Creates a logical disk with device identifier @a dev.
 *
 * A logical disk manages a subset of consecutive blocks containd in the
 * physical disk with identifier @a phys.  The start block index of the logical
 * disk device is @a start.  The block number of the logcal disk will be @a
 * size.  The blocks must be within the range of blocks managed by the
 * associated physical disk device.  A device node will be registered in the
 * file system with absolute path @a name.  The block size and IO control
 * handler are inherited by the physical disk.
 */
rtems_status_code rtems_disk_create_log(
  dev_t dev,
  dev_t phys,
  rtems_blkdev_bnum start,
  rtems_blkdev_bnum size,
  const char *name
);

/**
 * Deletes a physical or logical disk device with identifier @a dev.
 *
 * Disk devices may be deleted if there usage counter (and the usage counters
 * of all contained logical disks devices) equals zero.  When a physical disk
 * device is deleted, all logical disk devices will deleted too.  The
 * corresponding device nodes will be removed from the file system.
 */
rtems_status_code rtems_disk_delete(dev_t dev);

/**
 * Returns the disk device descriptor for the device identifier @a dev.
 *
 * Increments usage counter by one.  You should release the disk device
 * descriptor with rtems_disk_release().  Returns @c NULL if no corresponding
 * disk exists.
 */
rtems_disk_device *rtems_disk_obtain(dev_t dev);

/**
 * Releases the disk device description @a dd.
 *
 * Decrements usage counter by one.
 */
rtems_status_code rtems_disk_release(rtems_disk_device *dd);

/**
 * Disk device iterator.
 *
 * Returns the next disk device descriptor with a device identifier larger than
 * @a dev.  If there is no such device, @c NULL will be returned.  Use minus
 * one to start the search.
 *
 * @code
 * rtems_disk_device *dd = rtems_disk_next((dev_t) -1);
 *
 * while (dd != NULL) {
 *   dd = rtems_disk_next(dd->dev);
 * }
 * @endcode
 */
rtems_disk_device *rtems_disk_next(dev_t dev);

/**
 * Initializes the disk device management.
 *
 * This functions returns successful if the disk device management is already
 * initialized.  There is no protection against concurrent access.
 */
rtems_status_code rtems_disk_io_initialize(void);

/**
 * Releases all resources allocated for disk device management.
 */
rtems_status_code rtems_disk_io_done(void);

/** @} */

#ifdef __cplusplus
}
#endif

#endif