[net-next-2.6.git] / drivers / mtd / mtdblock.c

/*
 * Direct MTD block device access
 *
 * (C) 2000-2003 Nicolas Pitre <nico@fluxnic.net>
 * (C) 1999-2003 David Woodhouse <dwmw2@infradead.org>
 */

#include <linux/fs.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/types.h>
#include <linux/vmalloc.h>

#include <linux/mtd/mtd.h>
#include <linux/mtd/blktrans.h>
#include <linux/mutex.h>


static struct mtdblk_dev {
	struct mtd_info *mtd;
	int count;
	struct mutex cache_mutex;
	unsigned char *cache_data;
	unsigned long cache_offset;
	unsigned int cache_size;
	enum { STATE_EMPTY, STATE_CLEAN, STATE_DIRTY } cache_state;
} *mtdblks[MAX_MTD_DEVICES];

static struct mutex mtdblks_lock;

/*
 * Cache stuff...
 *
 * Since typical flash erasable sectors are much larger than what Linux's
 * buffer cache can handle, we must implement read-modify-write on flash
 * sectors for each block write requests.  To avoid over-erasing flash sectors
 * and to speed things up, we locally cache a whole flash sector while it is
 * being written to until a different sector is required.
 */

static void erase_callback(struct erase_info *done)
{
	wait_queue_head_t *wait_q = (wait_queue_head_t *)done->priv;
	wake_up(wait_q);
}

static int erase_write (struct mtd_info *mtd, unsigned long pos,
			int len, const char *buf)
{
	struct erase_info erase;
	DECLARE_WAITQUEUE(wait, current);
	wait_queue_head_t wait_q;
	size_t retlen;
	int ret;

	/*
	 * First, let's erase the flash block.
	 */

	init_waitqueue_head(&wait_q);
	erase.mtd = mtd;
	erase.callback = erase_callback;
	erase.addr = pos;
	erase.len = len;
	erase.priv = (u_long)&wait_q;

	set_current_state(TASK_INTERRUPTIBLE);
	add_wait_queue(&wait_q, &wait);

	ret = mtd->erase(mtd, &erase);
	if (ret) {
		set_current_state(TASK_RUNNING);
		remove_wait_queue(&wait_q, &wait);
		printk (KERN_WARNING "mtdblock: erase of region [0x%lx, 0x%x] "
				     "on \"%s\" failed\n",
			pos, len, mtd->name);
		return ret;
	}

	schedule();  /* Wait for erase to finish. */
	remove_wait_queue(&wait_q, &wait);

	/*
	 * Next, writhe data to flash.
	 */

	ret = mtd->write(mtd, pos, len, &retlen, buf);
	if (ret)
		return ret;
	if (retlen != len)
		return -EIO;
	return 0;
}


static int write_cached_data (struct mtdblk_dev *mtdblk)
{
	struct mtd_info *mtd = mtdblk->mtd;
	int ret;

	if (mtdblk->cache_state != STATE_DIRTY)
		return 0;

	DEBUG(MTD_DEBUG_LEVEL2, "mtdblock: writing cached data for \"%s\" "
			"at 0x%lx, size 0x%x\n", mtd->name,
			mtdblk->cache_offset, mtdblk->cache_size);

	ret = erase_write (mtd, mtdblk->cache_offset,
			   mtdblk->cache_size, mtdblk->cache_data);
	if (ret)
		return ret;

	/*
	 * Here we could argubly set the cache state to STATE_CLEAN.
	 * However this could lead to inconsistency since we will not
	 * be notified if this content is altered on the flash by other
	 * means.  Let's declare it empty and leave buffering tasks to
	 * the buffer cache instead.
	 */
	mtdblk->cache_state = STATE_EMPTY;
	return 0;
}


static int do_cached_write (struct mtdblk_dev *mtdblk, unsigned long pos,
			    int len, const char *buf)
{
	struct mtd_info *mtd = mtdblk->mtd;
	unsigned int sect_size = mtdblk->cache_size;
	size_t retlen;
	int ret;

	DEBUG(MTD_DEBUG_LEVEL2, "mtdblock: write on \"%s\" at 0x%lx, size 0x%x\n",
		mtd->name, pos, len);

	if (!sect_size)
		return mtd->write(mtd, pos, len, &retlen, buf);

	while (len > 0) {
		unsigned long sect_start = (pos/sect_size)*sect_size;
		unsigned int offset = pos - sect_start;
		unsigned int size = sect_size - offset;
		if( size > len )
			size = len;

		if (size == sect_size) {
			/*
			 * We are covering a whole sector.  Thus there is no
			 * need to bother with the cache while it may still be
			 * useful for other partial writes.
			 */
			ret = erase_write (mtd, pos, size, buf);
			if (ret)
				return ret;
		} else {
			/* Partial sector: need to use the cache */

			if (mtdblk->cache_state == STATE_DIRTY &&
			    mtdblk->cache_offset != sect_start) {
				ret = write_cached_data(mtdblk);
				if (ret)
					return ret;
			}

			if (mtdblk->cache_state == STATE_EMPTY ||
			    mtdblk->cache_offset != sect_start) {
				/* fill the cache with the current sector */
				mtdblk->cache_state = STATE_EMPTY;
				ret = mtd->read(mtd, sect_start, sect_size,
						&retlen, mtdblk->cache_data);
				if (ret)
					return ret;
				if (retlen != sect_size)
					return -EIO;

				mtdblk->cache_offset = sect_start;
				mtdblk->cache_size = sect_size;
				mtdblk->cache_state = STATE_CLEAN;
			}

			/* write data to our local cache */
			memcpy (mtdblk->cache_data + offset, buf, size);
			mtdblk->cache_state = STATE_DIRTY;
		}

		buf += size;
		pos += size;
		len -= size;
	}

	return 0;
}


static int do_cached_read (struct mtdblk_dev *mtdblk, unsigned long pos,
			   int len, char *buf)
{
	struct mtd_info *mtd = mtdblk->mtd;
	unsigned int sect_size = mtdblk->cache_size;
	size_t retlen;
	int ret;

	DEBUG(MTD_DEBUG_LEVEL2, "mtdblock: read on \"%s\" at 0x%lx, size 0x%x\n",
			mtd->name, pos, len);

	if (!sect_size)
		return mtd->read(mtd, pos, len, &retlen, buf);

	while (len > 0) {
		unsigned long sect_start = (pos/sect_size)*sect_size;
		unsigned int offset = pos - sect_start;
		unsigned int size = sect_size - offset;
		if (size > len)
			size = len;

		/*
		 * Check if the requested data is already cached
		 * Read the requested amount of data from our internal cache if it
		 * contains what we want, otherwise we read the data directly
		 * from flash.
		 */
		if (mtdblk->cache_state != STATE_EMPTY &&
		    mtdblk->cache_offset == sect_start) {
			memcpy (buf, mtdblk->cache_data + offset, size);
		} else {
			ret = mtd->read(mtd, pos, size, &retlen, buf);
			if (ret)
				return ret;
			if (retlen != size)
				return -EIO;
		}

		buf += size;
		pos += size;
		len -= size;
	}

	return 0;
}

static int mtdblock_readsect(struct mtd_blktrans_dev *dev,
			      unsigned long block, char *buf)
{
	struct mtdblk_dev *mtdblk = mtdblks[dev->devnum];
	return do_cached_read(mtdblk, block<<9, 512, buf);
}

static int mtdblock_writesect(struct mtd_blktrans_dev *dev,
			      unsigned long block, char *buf)
{
	struct mtdblk_dev *mtdblk = mtdblks[dev->devnum];
	if (unlikely(!mtdblk->cache_data && mtdblk->cache_size)) {
		mtdblk->cache_data = vmalloc(mtdblk->mtd->erasesize);
		if (!mtdblk->cache_data)
			return -EINTR;
		/* -EINTR is not really correct, but it is the best match
		 * documented in man 2 write for all cases.  We could also
		 * return -EAGAIN sometimes, but why bother?
		 */
	}
	return do_cached_write(mtdblk, block<<9, 512, buf);
}

static int mtdblock_open(struct mtd_blktrans_dev *mbd)
{
	struct mtdblk_dev *mtdblk;
	struct mtd_info *mtd = mbd->mtd;
	int dev = mbd->devnum;

	DEBUG(MTD_DEBUG_LEVEL1,"mtdblock_open\n");

	mutex_lock(&mtdblks_lock);
	if (mtdblks[dev]) {
		mtdblks[dev]->count++;
		mutex_unlock(&mtdblks_lock);
		return 0;
	}

	/* OK, it's not open. Create cache info for it */
	mtdblk = kzalloc(sizeof(struct mtdblk_dev), GFP_KERNEL);
	if (!mtdblk) {
		mutex_unlock(&mtdblks_lock);
		return -ENOMEM;
	}

	mtdblk->count = 1;
	mtdblk->mtd = mtd;

	mutex_init(&mtdblk->cache_mutex);
	mtdblk->cache_state = STATE_EMPTY;
	if ( !(mtdblk->mtd->flags & MTD_NO_ERASE) && mtdblk->mtd->erasesize) {
		mtdblk->cache_size = mtdblk->mtd->erasesize;
		mtdblk->cache_data = NULL;
	}

	mtdblks[dev] = mtdblk;
	mutex_unlock(&mtdblks_lock);

	DEBUG(MTD_DEBUG_LEVEL1, "ok\n");

	return 0;
}

static int mtdblock_release(struct mtd_blktrans_dev *mbd)
{
	int dev = mbd->devnum;
	struct mtdblk_dev *mtdblk = mtdblks[dev];

   	DEBUG(MTD_DEBUG_LEVEL1, "mtdblock_release\n");

	mutex_lock(&mtdblks_lock);

	mutex_lock(&mtdblk->cache_mutex);
	write_cached_data(mtdblk);
	mutex_unlock(&mtdblk->cache_mutex);

	if (!--mtdblk->count) {
		/* It was the last usage. Free the device */
		mtdblks[dev] = NULL;
		if (mtdblk->mtd->sync)
			mtdblk->mtd->sync(mtdblk->mtd);
		vfree(mtdblk->cache_data);
		kfree(mtdblk);
	}

	mutex_unlock(&mtdblks_lock);

	DEBUG(MTD_DEBUG_LEVEL1, "ok\n");

	return 0;
}

static int mtdblock_flush(struct mtd_blktrans_dev *dev)
{
	struct mtdblk_dev *mtdblk = mtdblks[dev->devnum];

	mutex_lock(&mtdblk->cache_mutex);
	write_cached_data(mtdblk);
	mutex_unlock(&mtdblk->cache_mutex);

	if (mtdblk->mtd->sync)
		mtdblk->mtd->sync(mtdblk->mtd);
	return 0;
}

static void mtdblock_add_mtd(struct mtd_blktrans_ops *tr, struct mtd_info *mtd)
{
	struct mtd_blktrans_dev *dev = kzalloc(sizeof(*dev), GFP_KERNEL);

	if (!dev)
		return;

	dev->mtd = mtd;
	dev->devnum = mtd->index;

	dev->size = mtd->size >> 9;
	dev->tr = tr;

	if (!(mtd->flags & MTD_WRITEABLE))
		dev->readonly = 1;

	add_mtd_blktrans_dev(dev);
}

static void mtdblock_remove_dev(struct mtd_blktrans_dev *dev)
{
	del_mtd_blktrans_dev(dev);
	kfree(dev);
}

static struct mtd_blktrans_ops mtdblock_tr = {
	.name		= "mtdblock",
	.major		= 31,
	.part_bits	= 0,
	.blksize 	= 512,
	.open		= mtdblock_open,
	.flush		= mtdblock_flush,
	.release	= mtdblock_release,
	.readsect	= mtdblock_readsect,
	.writesect	= mtdblock_writesect,
	.add_mtd	= mtdblock_add_mtd,
	.remove_dev	= mtdblock_remove_dev,
	.owner		= THIS_MODULE,
};

static int __init init_mtdblock(void)
{
	mutex_init(&mtdblks_lock);

	return register_mtd_blktrans(&mtdblock_tr);
}

static void __exit cleanup_mtdblock(void)
{
	deregister_mtd_blktrans(&mtdblock_tr);
}

module_init(init_mtdblock);
module_exit(cleanup_mtdblock);


MODULE_LICENSE("GPL");
MODULE_AUTHOR("Nicolas Pitre <nico@fluxnic.net> et al.");
MODULE_DESCRIPTION("Caching read/erase/writeback block device emulation access to MTD devices");
Commit	Line	Data
97894cda	1	/*
1da177e4 LT	2	* Direct MTD block device access
1da177e4 LT	3	*
2f82af08	4	* (C) 2000-2003 Nicolas Pitre <nico@fluxnic.net>
1da177e4 LT	5	* (C) 1999-2003 David Woodhouse <dwmw2@infradead.org>
	6	*/
	7
1da177e4 LT	8	#include <linux/fs.h>
1da177e4 LT	9	#include <linux/init.h>
15fdc52f TG	10	#include <linux/kernel.h>
	11	#include <linux/module.h>
	12	#include <linux/sched.h>
1da177e4	13	#include <linux/slab.h>
15fdc52f	14	#include <linux/types.h>
1da177e4	15	#include <linux/vmalloc.h>
15fdc52f	16
1da177e4 LT	17	#include <linux/mtd/mtd.h>
1da177e4 LT	18	#include <linux/mtd/blktrans.h>
48b19268 IM	19	#include <linux/mutex.h>
48b19268 IM	20
1da177e4 LT	21
	22	static struct mtdblk_dev {
	23	struct mtd_info *mtd;
	24	int count;
48b19268	25	struct mutex cache_mutex;
1da177e4 LT	26	unsigned char *cache_data;
	27	unsigned long cache_offset;
	28	unsigned int cache_size;
	29	enum { STATE_EMPTY, STATE_CLEAN, STATE_DIRTY } cache_state;
	30	} *mtdblks[MAX_MTD_DEVICES];
	31
d676c117 MK	32	static struct mutex mtdblks_lock;
d676c117 MK	33
1da177e4 LT	34	/*
1da177e4 LT	35	* Cache stuff...
97894cda	36	*
1da177e4 LT	37	* Since typical flash erasable sectors are much larger than what Linux's
	38	* buffer cache can handle, we must implement read-modify-write on flash
	39	* sectors for each block write requests. To avoid over-erasing flash sectors
	40	* and to speed things up, we locally cache a whole flash sector while it is
	41	* being written to until a different sector is required.
	42	*/
	43
	44	static void erase_callback(struct erase_info *done)
	45	{
	46	wait_queue_head_t wait_q = (wait_queue_head_t )done->priv;
	47	wake_up(wait_q);
	48	}
	49
97894cda	50	static int erase_write (struct mtd_info *mtd, unsigned long pos,
1da177e4 LT	51	int len, const char *buf)
	52	{
	53	struct erase_info erase;
	54	DECLARE_WAITQUEUE(wait, current);
	55	wait_queue_head_t wait_q;
	56	size_t retlen;
	57	int ret;
	58
	59	/*
	60	* First, let's erase the flash block.
	61	*/
	62
	63	init_waitqueue_head(&wait_q);
	64	erase.mtd = mtd;
	65	erase.callback = erase_callback;
	66	erase.addr = pos;
	67	erase.len = len;
	68	erase.priv = (u_long)&wait_q;
	69
	70	set_current_state(TASK_INTERRUPTIBLE);
	71	add_wait_queue(&wait_q, &wait);
	72
f4a43cfc	73	ret = mtd->erase(mtd, &erase);
1da177e4 LT	74	if (ret) {
	75	set_current_state(TASK_RUNNING);
	76	remove_wait_queue(&wait_q, &wait);
	77	printk (KERN_WARNING "mtdblock: erase of region [0x%lx, 0x%x] "
	78	"on \"%s\" failed\n",
	79	pos, len, mtd->name);
	80	return ret;
	81	}
	82
	83	schedule(); /* Wait for erase to finish. */
	84	remove_wait_queue(&wait_q, &wait);
	85
	86	/*
	87	* Next, writhe data to flash.
	88	*/
	89
f4a43cfc	90	ret = mtd->write(mtd, pos, len, &retlen, buf);
1da177e4 LT	91	if (ret)
	92	return ret;
	93	if (retlen != len)
	94	return -EIO;
	95	return 0;
	96	}
	97
	98
	99	static int write_cached_data (struct mtdblk_dev *mtdblk)
	100	{
	101	struct mtd_info *mtd = mtdblk->mtd;
	102	int ret;
	103
	104	if (mtdblk->cache_state != STATE_DIRTY)
	105	return 0;
	106
	107	DEBUG(MTD_DEBUG_LEVEL2, "mtdblock: writing cached data for \"%s\" "
97894cda	108	"at 0x%lx, size 0x%x\n", mtd->name,
1da177e4	109	mtdblk->cache_offset, mtdblk->cache_size);
97894cda TG	110
97894cda TG	111	ret = erase_write (mtd, mtdblk->cache_offset,
1da177e4 LT	112	mtdblk->cache_size, mtdblk->cache_data);
	113	if (ret)
	114	return ret;
	115
	116	/*
	117	* Here we could argubly set the cache state to STATE_CLEAN.
97894cda TG	118	* However this could lead to inconsistency since we will not
97894cda TG	119	* be notified if this content is altered on the flash by other
1da177e4 LT	120	* means. Let's declare it empty and leave buffering tasks to
	121	* the buffer cache instead.
	122	*/
	123	mtdblk->cache_state = STATE_EMPTY;
	124	return 0;
	125	}
	126
	127
97894cda	128	static int do_cached_write (struct mtdblk_dev *mtdblk, unsigned long pos,
1da177e4 LT	129	int len, const char *buf)
	130	{
	131	struct mtd_info *mtd = mtdblk->mtd;
	132	unsigned int sect_size = mtdblk->cache_size;
	133	size_t retlen;
	134	int ret;
	135
	136	DEBUG(MTD_DEBUG_LEVEL2, "mtdblock: write on \"%s\" at 0x%lx, size 0x%x\n",
	137	mtd->name, pos, len);
97894cda	138
1da177e4	139	if (!sect_size)
f4a43cfc	140	return mtd->write(mtd, pos, len, &retlen, buf);
1da177e4 LT	141
	142	while (len > 0) {
	143	unsigned long sect_start = (pos/sect_size)*sect_size;
	144	unsigned int offset = pos - sect_start;
	145	unsigned int size = sect_size - offset;
97894cda	146	if( size > len )
1da177e4 LT	147	size = len;
	148
	149	if (size == sect_size) {
97894cda	150	/*
1da177e4 LT	151	* We are covering a whole sector. Thus there is no
	152	* need to bother with the cache while it may still be
	153	* useful for other partial writes.
	154	*/
	155	ret = erase_write (mtd, pos, size, buf);
	156	if (ret)
	157	return ret;
	158	} else {
	159	/* Partial sector: need to use the cache */
	160
	161	if (mtdblk->cache_state == STATE_DIRTY &&
	162	mtdblk->cache_offset != sect_start) {
	163	ret = write_cached_data(mtdblk);
97894cda	164	if (ret)
1da177e4 LT	165	return ret;
	166	}
	167
	168	if (mtdblk->cache_state == STATE_EMPTY \|\|
	169	mtdblk->cache_offset != sect_start) {
	170	/* fill the cache with the current sector */
	171	mtdblk->cache_state = STATE_EMPTY;
f4a43cfc TG	172	ret = mtd->read(mtd, sect_start, sect_size,
f4a43cfc TG	173	&retlen, mtdblk->cache_data);
1da177e4 LT	174	if (ret)
	175	return ret;
	176	if (retlen != sect_size)
	177	return -EIO;
	178
	179	mtdblk->cache_offset = sect_start;
	180	mtdblk->cache_size = sect_size;
	181	mtdblk->cache_state = STATE_CLEAN;
	182	}
	183
	184	/* write data to our local cache */
	185	memcpy (mtdblk->cache_data + offset, buf, size);
	186	mtdblk->cache_state = STATE_DIRTY;
	187	}
	188
	189	buf += size;
	190	pos += size;
	191	len -= size;
	192	}
	193
	194	return 0;
	195	}
	196
	197
97894cda	198	static int do_cached_read (struct mtdblk_dev *mtdblk, unsigned long pos,
1da177e4 LT	199	int len, char *buf)
	200	{
	201	struct mtd_info *mtd = mtdblk->mtd;
	202	unsigned int sect_size = mtdblk->cache_size;
	203	size_t retlen;
	204	int ret;
	205
97894cda	206	DEBUG(MTD_DEBUG_LEVEL2, "mtdblock: read on \"%s\" at 0x%lx, size 0x%x\n",
1da177e4	207	mtd->name, pos, len);
97894cda	208
1da177e4	209	if (!sect_size)
f4a43cfc	210	return mtd->read(mtd, pos, len, &retlen, buf);
1da177e4 LT	211
	212	while (len > 0) {
	213	unsigned long sect_start = (pos/sect_size)*sect_size;
	214	unsigned int offset = pos - sect_start;
	215	unsigned int size = sect_size - offset;
97894cda	216	if (size > len)
1da177e4 LT	217	size = len;
	218
	219	/*
	220	* Check if the requested data is already cached
	221	* Read the requested amount of data from our internal cache if it
	222	* contains what we want, otherwise we read the data directly
	223	* from flash.
	224	*/
	225	if (mtdblk->cache_state != STATE_EMPTY &&
	226	mtdblk->cache_offset == sect_start) {
	227	memcpy (buf, mtdblk->cache_data + offset, size);
	228	} else {
f4a43cfc	229	ret = mtd->read(mtd, pos, size, &retlen, buf);
1da177e4 LT	230	if (ret)
	231	return ret;
	232	if (retlen != size)
	233	return -EIO;
	234	}
	235
	236	buf += size;
	237	pos += size;
	238	len -= size;
	239	}
	240
	241	return 0;
	242	}
	243
	244	static int mtdblock_readsect(struct mtd_blktrans_dev *dev,
	245	unsigned long block, char *buf)
	246	{
	247	struct mtdblk_dev *mtdblk = mtdblks[dev->devnum];
	248	return do_cached_read(mtdblk, block<<9, 512, buf);
	249	}
	250
	251	static int mtdblock_writesect(struct mtd_blktrans_dev *dev,
	252	unsigned long block, char *buf)
	253	{
	254	struct mtdblk_dev *mtdblk = mtdblks[dev->devnum];
	255	if (unlikely(!mtdblk->cache_data && mtdblk->cache_size)) {
	256	mtdblk->cache_data = vmalloc(mtdblk->mtd->erasesize);
	257	if (!mtdblk->cache_data)
	258	return -EINTR;
	259	/* -EINTR is not really correct, but it is the best match
	260	* documented in man 2 write for all cases. We could also
	261	* return -EAGAIN sometimes, but why bother?
	262	*/
	263	}
	264	return do_cached_write(mtdblk, block<<9, 512, buf);
	265	}
	266
	267	static int mtdblock_open(struct mtd_blktrans_dev *mbd)
	268	{
	269	struct mtdblk_dev *mtdblk;
	270	struct mtd_info *mtd = mbd->mtd;
	271	int dev = mbd->devnum;
	272
	273	DEBUG(MTD_DEBUG_LEVEL1,"mtdblock_open\n");
97894cda	274
d676c117	275	mutex_lock(&mtdblks_lock);
1da177e4 LT	276	if (mtdblks[dev]) {
1da177e4 LT	277	mtdblks[dev]->count++;
d676c117	278	mutex_unlock(&mtdblks_lock);
1da177e4 LT	279	return 0;
1da177e4 LT	280	}
97894cda	281
1da177e4	282	/* OK, it's not open. Create cache info for it */
95b93a0c	283	mtdblk = kzalloc(sizeof(struct mtdblk_dev), GFP_KERNEL);
d676c117 MK	284	if (!mtdblk) {
d676c117 MK	285	mutex_unlock(&mtdblks_lock);
1da177e4	286	return -ENOMEM;
d676c117	287	}
1da177e4	288
1da177e4 LT	289	mtdblk->count = 1;
	290	mtdblk->mtd = mtd;
	291
48b19268	292	mutex_init(&mtdblk->cache_mutex);
1da177e4	293	mtdblk->cache_state = STATE_EMPTY;
92cbfdcc	294	if ( !(mtdblk->mtd->flags & MTD_NO_ERASE) && mtdblk->mtd->erasesize) {
1da177e4 LT	295	mtdblk->cache_size = mtdblk->mtd->erasesize;
	296	mtdblk->cache_data = NULL;
	297	}
	298
	299	mtdblks[dev] = mtdblk;
d676c117	300	mutex_unlock(&mtdblks_lock);
97894cda	301
1da177e4 LT	302	DEBUG(MTD_DEBUG_LEVEL1, "ok\n");
	303
	304	return 0;
	305	}
	306
	307	static int mtdblock_release(struct mtd_blktrans_dev *mbd)
	308	{
	309	int dev = mbd->devnum;
	310	struct mtdblk_dev *mtdblk = mtdblks[dev];
	311
	312	DEBUG(MTD_DEBUG_LEVEL1, "mtdblock_release\n");
	313
d676c117 MK	314	mutex_lock(&mtdblks_lock);
d676c117 MK	315
48b19268	316	mutex_lock(&mtdblk->cache_mutex);
1da177e4	317	write_cached_data(mtdblk);
48b19268	318	mutex_unlock(&mtdblk->cache_mutex);
1da177e4 LT	319
	320	if (!--mtdblk->count) {
	321	/* It was the last usage. Free the device */
	322	mtdblks[dev] = NULL;
	323	if (mtdblk->mtd->sync)
	324	mtdblk->mtd->sync(mtdblk->mtd);
	325	vfree(mtdblk->cache_data);
	326	kfree(mtdblk);
	327	}
d676c117 MK	328
	329	mutex_unlock(&mtdblks_lock);
	330
1da177e4 LT	331	DEBUG(MTD_DEBUG_LEVEL1, "ok\n");
	332
	333	return 0;
97894cda	334	}
1da177e4 LT	335
	336	static int mtdblock_flush(struct mtd_blktrans_dev *dev)
	337	{
	338	struct mtdblk_dev *mtdblk = mtdblks[dev->devnum];
	339
48b19268	340	mutex_lock(&mtdblk->cache_mutex);
1da177e4	341	write_cached_data(mtdblk);
48b19268	342	mutex_unlock(&mtdblk->cache_mutex);
1da177e4 LT	343
	344	if (mtdblk->mtd->sync)
	345	mtdblk->mtd->sync(mtdblk->mtd);
	346	return 0;
	347	}
	348
	349	static void mtdblock_add_mtd(struct mtd_blktrans_ops tr, struct mtd_info mtd)
	350	{
95b93a0c	351	struct mtd_blktrans_dev dev = kzalloc(sizeof(dev), GFP_KERNEL);
1da177e4 LT	352
	353	if (!dev)
	354	return;
	355
1da177e4 LT	356	dev->mtd = mtd;
1da177e4 LT	357	dev->devnum = mtd->index;
19187672	358
1da177e4 LT	359	dev->size = mtd->size >> 9;
	360	dev->tr = tr;
	361
	362	if (!(mtd->flags & MTD_WRITEABLE))
	363	dev->readonly = 1;
	364
	365	add_mtd_blktrans_dev(dev);
	366	}
	367
	368	static void mtdblock_remove_dev(struct mtd_blktrans_dev *dev)
	369	{
	370	del_mtd_blktrans_dev(dev);
	371	kfree(dev);
	372	}
	373
	374	static struct mtd_blktrans_ops mtdblock_tr = {
	375	.name = "mtdblock",
	376	.major = 31,
	377	.part_bits = 0,
19187672	378	.blksize = 512,
1da177e4 LT	379	.open = mtdblock_open,
	380	.flush = mtdblock_flush,
	381	.release = mtdblock_release,
	382	.readsect = mtdblock_readsect,
	383	.writesect = mtdblock_writesect,
	384	.add_mtd = mtdblock_add_mtd,
	385	.remove_dev = mtdblock_remove_dev,
	386	.owner = THIS_MODULE,
	387	};
	388
	389	static int __init init_mtdblock(void)
	390	{
d676c117 MK	391	mutex_init(&mtdblks_lock);
d676c117 MK	392
1da177e4 LT	393	return register_mtd_blktrans(&mtdblock_tr);
	394	}
	395
	396	static void __exit cleanup_mtdblock(void)
	397	{
	398	deregister_mtd_blktrans(&mtdblock_tr);
	399	}
	400
	401	module_init(init_mtdblock);
	402	module_exit(cleanup_mtdblock);
	403
	404
	405	MODULE_LICENSE("GPL");
2f82af08	406	MODULE_AUTHOR("Nicolas Pitre <nico@fluxnic.net> et al.");
1da177e4	407	MODULE_DESCRIPTION("Caching read/erase/writeback block device emulation access to MTD devices");