diskdevs.c

RTEMS (Real-Time Executive for Multiprocessor Systems) is a free open source real-time operating sys

    disk_device *pdd;
    rtems_status_code rc;
    rtems_device_major_number major;
    rtems_device_minor_number minor;

    rtems_filesystem_split_dev_t (dev, major, minor);

    rc = rtems_semaphore_obtain(diskdevs_mutex, RTEMS_WAIT, RTEMS_NO_TIMEOUT);
    if (rc != RTEMS_SUCCESSFUL)
        return rc;
    diskdevs_protected = TRUE;

    pdd = get_disk_entry(phys);
    if (pdd == NULL)
    {
        diskdevs_protected = FALSE;
        rtems_semaphore_release(diskdevs_mutex);
        return RTEMS_INVALID_NUMBER;
    }
    
    rc = create_disk(dev, name, &dd);
    if (rc != RTEMS_SUCCESSFUL)
    {
        diskdevs_protected = FALSE;
        rtems_semaphore_release(diskdevs_mutex);
        return rc;
    }
    
    dd->phys_dev = pdd;
    dd->uses = 0;
    dd->start = start;
    dd->size = size;
    dd->block_size = pdd->block_size;
    dd->block_size_log2 = pdd->block_size_log2;
    dd->ioctl = pdd->ioctl;

    rc = rtems_io_register_name(name, major, minor);

    diskdevs_protected = FALSE;
    rc = rtems_semaphore_release(diskdevs_mutex);
    
    return rc;
}

/* rtems_disk_delete --
 *     Delete physical or logical disk device. Device may be deleted if its
 *     use counter (and use counters of all logical devices - if it is
 *     physical device) equal to 0. When physical device deleted,
 *     all logical devices deleted inherently. Appropriate devices removed
 *     from "/dev" filesystem.
 *
 * PARAMETERS:
 *     dev - device identifier (major, minor numbers)
 *
 * RETURNS:
 *     RTEMS_SUCCESSFUL if block device successfully deleted, or error code
 *     if error occured (device is not defined, device is in use).
 */
rtems_status_code
rtems_disk_delete(dev_t dev)
{
    rtems_status_code rc;
    int used;
    rtems_device_major_number maj;
    rtems_device_minor_number min;
    
    rc = rtems_semaphore_obtain(diskdevs_mutex, RTEMS_WAIT, RTEMS_NO_TIMEOUT);
    if (rc != RTEMS_SUCCESSFUL)
        return rc;
    diskdevs_protected = TRUE;

    /* Check if this device is in use -- calculate usage counter */
    used = 0;
    for (maj = 0; maj < disktab_size; maj++)
    {
        struct disk_device_table *dtab = disktab + maj;
        if (dtab != NULL)
        {
            for (min = 0; min < dtab->size; min++)
            {
                disk_device *dd = dtab->minor[min];
                if ((dd != NULL) && (dd->phys_dev->dev == dev))
                    used += dd->uses;
            }
        }
    }
    
    if (used != 0)
    {
        diskdevs_protected = FALSE;
        rtems_semaphore_release(diskdevs_mutex);
        return RTEMS_RESOURCE_IN_USE;
    }

    /* Delete this device and all of its logical devices */
    for (maj = 0; maj < disktab_size; maj++)
    {
        struct disk_device_table *dtab = disktab +maj;
        if (dtab != NULL)
        {
            for (min = 0; min < dtab->size; min++)
            {
                disk_device *dd = dtab->minor[min];
                if ((dd != NULL) && (dd->phys_dev->dev == dev))
                {
                    unlink(dd->name);
                    free(dd->name);
                    free(dd);
                    dtab->minor[min] = NULL;
                }
            }
        }
    }
    
    diskdevs_protected = FALSE;
    rc = rtems_semaphore_release(diskdevs_mutex);
    return rc;
}

/* rtems_disk_lookup --
 *     Find block device descriptor by its device identifier.
 *
 * PARAMETERS:
 *     dev - device identifier (major, minor numbers)
 *
 * RETURNS:
 *     pointer to the block device descriptor, or NULL if no such device
 *     exists.
 */
disk_device *
rtems_disk_lookup(dev_t dev)
{
    rtems_interrupt_level level;
    disk_device *dd;
    rtems_status_code rc;
    
    rtems_interrupt_disable(level);
    if (diskdevs_protected)
    {
        rtems_interrupt_enable(level);
        rc = rtems_semaphore_obtain(diskdevs_mutex, RTEMS_WAIT, 
                                    RTEMS_NO_TIMEOUT);
        if (rc != RTEMS_SUCCESSFUL)
            return NULL;
        diskdevs_protected = TRUE;
        dd = get_disk_entry(dev);
        dd->uses++;
        diskdevs_protected = FALSE;
        rtems_semaphore_release(diskdevs_mutex);
        return dd;
    }
    else
    {
        /* Frequent and quickest case */
        dd = get_disk_entry(dev);
        dd->uses++;
        rtems_interrupt_enable(level);
        return dd;
    }
}

/* rtems_disk_release --
 *     Release disk_device structure (decrement usage counter to 1).
 *
 * PARAMETERS:
 *     dd - pointer to disk device structure
 *
 * RETURNS:
 *     RTEMS_SUCCESSFUL
 */
rtems_status_code
rtems_disk_release(disk_device *dd)
{
    rtems_interrupt_level level;
    rtems_interrupt_disable(level);
    dd->uses--;
    rtems_interrupt_enable(level);
    return RTEMS_SUCCESSFUL;
}

/* rtems_disk_next --
 *     Disk device enumerator. Looking for device having device number larger
 *     than dev and return disk device descriptor for it. If there are no
 *     such device, NULL value returned.
 *
 * PARAMETERS:
 *     dev - device number (use -1 to start search)
 *
 * RETURNS:
 *     Pointer to the disk descriptor for next disk device, or NULL if all
 *     devices enumerated.
 */
disk_device *
rtems_disk_next(dev_t dev)
{
    rtems_device_major_number major;
    rtems_device_minor_number minor;
    struct disk_device_table *dtab;

    dev++;
    rtems_filesystem_split_dev_t (dev, major, minor);

    if (major >= disktab_size)
        return NULL;
    
    dtab = disktab + major;
    while (TRUE) 
    {
        if ((dtab == NULL) || (minor > dtab->size))
        {
             major++; minor = 0;
             if (major >= disktab_size)
                 return NULL;
             dtab = disktab + major;
        }
        else if (dtab->minor[minor] == NULL)
        {
            minor++;
        }
        else
            return dtab->minor[minor];
    }
}

/* rtems_disk_initialize --
 *     Initialization of disk device library (initialize all data structures,
 *     etc.)
 *
 * PARAMETERS:
 *     none
 *
 * RETURNS:
 *     RTEMS_SUCCESSFUL if library initialized, or error code if error 
 *     occured.
 */
rtems_status_code
rtems_disk_io_initialize(void)
{
    rtems_status_code rc;

    if (disk_io_initialized)
        return RTEMS_SUCCESSFUL;
    
    disktab_size = DISKTAB_INITIAL_SIZE;
    disktab = calloc(disktab_size, sizeof(struct disk_device_table));
    if (disktab == NULL)
        return RTEMS_NO_MEMORY;

    diskdevs_protected = FALSE;
    rc = rtems_semaphore_create(
        rtems_build_name('D', 'D', 'E', 'V'), 1,
        RTEMS_FIFO | RTEMS_BINARY_SEMAPHORE | RTEMS_NO_INHERIT_PRIORITY | 
        RTEMS_NO_PRIORITY_CEILING | RTEMS_LOCAL, 0, &diskdevs_mutex);
    
    if (rc != RTEMS_SUCCESSFUL)
    {
        free(disktab);
        return rc;
    }
    
    rc = rtems_bdbuf_init(rtems_bdbuf_configuration,
                          rtems_bdbuf_configuration_size);
    
    if (rc != RTEMS_SUCCESSFUL)
    {
        rtems_semaphore_delete(diskdevs_mutex);
        free(disktab);
        return rc;
    }
    
    disk_io_initialized = 1;
    return RTEMS_SUCCESSFUL;
}

/* rtems_disk_io_done --
 *     Release all resources allocated for disk device interface.
 *
 * PARAMETERS:
 *     none
 *
 * RETURNS:
 *     RTEMS_SUCCESSFUL if all resources released, or error code if error 
 *     occured.
 */
rtems_status_code
rtems_disk_io_done(void)
{
    rtems_device_major_number maj;
    rtems_device_minor_number min;
    rtems_status_code rc;

    /* Free data structures */    
    for (maj = 0; maj < disktab_size; maj++)
    {
        struct disk_device_table *dtab = disktab + maj;
        if (dtab != NULL)
        {
            for (min = 0; min < dtab->size; min++)
            {
                disk_device *dd = dtab->minor[min];
                unlink(dd->name);
                free(dd->name);
                free(dd);
            }
            free(dtab);
        }
    }
    free(disktab);

    rc = rtems_semaphore_release(diskdevs_mutex);
    
    /* XXX bdbuf should be released too! */
    disk_io_initialized = 0;
    return rc;
}