[mirror_ubuntu-zesty-kernel.git] / drivers / mtd / mtdblock.c

/*
 * Direct MTD block device access
 *
 * Copyright © 1999-2010 David Woodhouse <dwmw2@infradead.org>
 * Copyright © 2000-2003 Nicolas Pitre <nico@fluxnic.net>
 *
 * This program 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 2 of the License, or
 * (at your option) any later version.
 *
 * This program 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 this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 *
 */

#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>
#include <linux/major.h>


struct mtdblk_dev {
	struct mtd_blktrans_dev mbd;
	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;
};

/*
 * 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, write the 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->mbd.mtd;
	int ret;

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

	pr_debug("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 arguably 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->mbd.mtd;
	unsigned int sect_size = mtdblk->cache_size;
	size_t retlen;
	int ret;

	pr_debug("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->mbd.mtd;
	unsigned int sect_size = mtdblk->cache_size;
	size_t retlen;
	int ret;

	pr_debug("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 = container_of(dev, struct mtdblk_dev, mbd);
	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 = container_of(dev, struct mtdblk_dev, mbd);
	if (unlikely(!mtdblk->cache_data && mtdblk->cache_size)) {
		mtdblk->cache_data = vmalloc(mtdblk->mbd.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 = container_of(mbd, struct mtdblk_dev, mbd);

	pr_debug("mtdblock_open\n");

	if (mtdblk->count) {
		mtdblk->count++;
		return 0;
	}

	/* OK, it's not open. Create cache info for it */
	mtdblk->count = 1;
	mutex_init(&mtdblk->cache_mutex);
	mtdblk->cache_state = STATE_EMPTY;
	if (!(mbd->mtd->flags & MTD_NO_ERASE) && mbd->mtd->erasesize) {
		mtdblk->cache_size = mbd->mtd->erasesize;
		mtdblk->cache_data = NULL;
	}

	pr_debug("ok\n");

	return 0;
}

static void mtdblock_release(struct mtd_blktrans_dev *mbd)
{
	struct mtdblk_dev *mtdblk = container_of(mbd, struct mtdblk_dev, mbd);

	pr_debug("mtdblock_release\n");

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

	if (!--mtdblk->count) {
		/*
		 * It was the last usage. Free the cache, but only sync if
		 * opened for writing.
		 */
		if (mbd->file_mode & FMODE_WRITE)
			mtd_sync(mbd->mtd);
		vfree(mtdblk->cache_data);
	}

	pr_debug("ok\n");
}

static int mtdblock_flush(struct mtd_blktrans_dev *dev)
{
	struct mtdblk_dev *mtdblk = container_of(dev, struct mtdblk_dev, mbd);

	mutex_lock(&mtdblk->cache_mutex);
	write_cached_data(mtdblk);
	mutex_unlock(&mtdblk->cache_mutex);
	mtd_sync(dev->mtd);
	return 0;
}

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

	if (!dev)
		return;

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

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

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

	if (add_mtd_blktrans_dev(&dev->mbd))
		kfree(dev);
}

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

static struct mtd_blktrans_ops mtdblock_tr = {
	.name		= "mtdblock",
	.major		= MTD_BLOCK_MAJOR,
	.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)
{
	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	*
a1452a37 DW	4	* Copyright © 1999-2010 David Woodhouse <dwmw2@infradead.org>
	5	* Copyright © 2000-2003 Nicolas Pitre <nico@fluxnic.net>
	6	*
	7	* This program is free software; you can redistribute it and/or modify
	8	* it under the terms of the GNU General Public License as published by
	9	* the Free Software Foundation; either version 2 of the License, or
	10	* (at your option) any later version.
	11	*
	12	* This program is distributed in the hope that it will be useful,
	13	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	14	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	15	* GNU General Public License for more details.
	16	*
	17	* You should have received a copy of the GNU General Public License
	18	* along with this program; if not, write to the Free Software
	19	* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
	20	*
1da177e4 LT	21	*/
1da177e4 LT	22
1da177e4 LT	23	#include <linux/fs.h>
1da177e4 LT	24	#include <linux/init.h>
15fdc52f TG	25	#include <linux/kernel.h>
	26	#include <linux/module.h>
	27	#include <linux/sched.h>
1da177e4	28	#include <linux/slab.h>
15fdc52f	29	#include <linux/types.h>
1da177e4	30	#include <linux/vmalloc.h>
15fdc52f	31
1da177e4 LT	32	#include <linux/mtd/mtd.h>
1da177e4 LT	33	#include <linux/mtd/blktrans.h>
48b19268	34	#include <linux/mutex.h>
f83c3838	35	#include <linux/major.h>
48b19268	36
1da177e4	37
cbfe93e9 BH	38	struct mtdblk_dev {
cbfe93e9 BH	39	struct mtd_blktrans_dev mbd;
1da177e4	40	int count;
48b19268	41	struct mutex cache_mutex;
1da177e4 LT	42	unsigned char *cache_data;
	43	unsigned long cache_offset;
	44	unsigned int cache_size;
	45	enum { STATE_EMPTY, STATE_CLEAN, STATE_DIRTY } cache_state;
cbfe93e9	46	};
1da177e4 LT	47
	48	/*
	49	* Cache stuff...
97894cda	50	*
1da177e4 LT	51	* Since typical flash erasable sectors are much larger than what Linux's
	52	* buffer cache can handle, we must implement read-modify-write on flash
	53	* sectors for each block write requests. To avoid over-erasing flash sectors
	54	* and to speed things up, we locally cache a whole flash sector while it is
	55	* being written to until a different sector is required.
	56	*/
	57
	58	static void erase_callback(struct erase_info *done)
	59	{
	60	wait_queue_head_t wait_q = (wait_queue_head_t )done->priv;
	61	wake_up(wait_q);
	62	}
	63
97894cda	64	static int erase_write (struct mtd_info *mtd, unsigned long pos,
1da177e4 LT	65	int len, const char *buf)
	66	{
	67	struct erase_info erase;
	68	DECLARE_WAITQUEUE(wait, current);
	69	wait_queue_head_t wait_q;
	70	size_t retlen;
	71	int ret;
	72
	73	/*
	74	* First, let's erase the flash block.
	75	*/
	76
	77	init_waitqueue_head(&wait_q);
	78	erase.mtd = mtd;
	79	erase.callback = erase_callback;
	80	erase.addr = pos;
	81	erase.len = len;
	82	erase.priv = (u_long)&wait_q;
	83
	84	set_current_state(TASK_INTERRUPTIBLE);
	85	add_wait_queue(&wait_q, &wait);
	86
7e1f0dc0	87	ret = mtd_erase(mtd, &erase);
1da177e4 LT	88	if (ret) {
	89	set_current_state(TASK_RUNNING);
	90	remove_wait_queue(&wait_q, &wait);
	91	printk (KERN_WARNING "mtdblock: erase of region [0x%lx, 0x%x] "
	92	"on \"%s\" failed\n",
	93	pos, len, mtd->name);
	94	return ret;
	95	}
	96
	97	schedule(); /* Wait for erase to finish. */
	98	remove_wait_queue(&wait_q, &wait);
	99
	100	/*
dff15509	101	* Next, write the data to flash.
1da177e4 LT	102	*/
1da177e4 LT	103
eda95cbf	104	ret = mtd_write(mtd, pos, len, &retlen, buf);
1da177e4 LT	105	if (ret)
	106	return ret;
	107	if (retlen != len)
	108	return -EIO;
	109	return 0;
	110	}
	111
	112
	113	static int write_cached_data (struct mtdblk_dev *mtdblk)
	114	{
cbfe93e9	115	struct mtd_info *mtd = mtdblk->mbd.mtd;
1da177e4 LT	116	int ret;
	117
	118	if (mtdblk->cache_state != STATE_DIRTY)
	119	return 0;
	120
289c0522	121	pr_debug("mtdblock: writing cached data for \"%s\" "
97894cda	122	"at 0x%lx, size 0x%x\n", mtd->name,
1da177e4	123	mtdblk->cache_offset, mtdblk->cache_size);
97894cda TG	124
97894cda TG	125	ret = erase_write (mtd, mtdblk->cache_offset,
1da177e4 LT	126	mtdblk->cache_size, mtdblk->cache_data);
	127	if (ret)
	128	return ret;
	129
	130	/*
25985edc	131	* Here we could arguably set the cache state to STATE_CLEAN.
97894cda TG	132	* However this could lead to inconsistency since we will not
97894cda TG	133	* be notified if this content is altered on the flash by other
1da177e4 LT	134	* means. Let's declare it empty and leave buffering tasks to
	135	* the buffer cache instead.
	136	*/
	137	mtdblk->cache_state = STATE_EMPTY;
	138	return 0;
	139	}
	140
	141
97894cda	142	static int do_cached_write (struct mtdblk_dev *mtdblk, unsigned long pos,
1da177e4 LT	143	int len, const char *buf)
1da177e4 LT	144	{
cbfe93e9	145	struct mtd_info *mtd = mtdblk->mbd.mtd;
1da177e4 LT	146	unsigned int sect_size = mtdblk->cache_size;
	147	size_t retlen;
	148	int ret;
	149
289c0522	150	pr_debug("mtdblock: write on \"%s\" at 0x%lx, size 0x%x\n",
1da177e4	151	mtd->name, pos, len);
97894cda	152
1da177e4	153	if (!sect_size)
eda95cbf	154	return mtd_write(mtd, pos, len, &retlen, buf);
1da177e4 LT	155
	156	while (len > 0) {
	157	unsigned long sect_start = (pos/sect_size)*sect_size;
	158	unsigned int offset = pos - sect_start;
	159	unsigned int size = sect_size - offset;
97894cda	160	if( size > len )
1da177e4 LT	161	size = len;
	162
	163	if (size == sect_size) {
97894cda	164	/*
1da177e4 LT	165	* We are covering a whole sector. Thus there is no
	166	* need to bother with the cache while it may still be
	167	* useful for other partial writes.
	168	*/
	169	ret = erase_write (mtd, pos, size, buf);
	170	if (ret)
	171	return ret;
	172	} else {
	173	/* Partial sector: need to use the cache */
	174
	175	if (mtdblk->cache_state == STATE_DIRTY &&
	176	mtdblk->cache_offset != sect_start) {
	177	ret = write_cached_data(mtdblk);
97894cda	178	if (ret)
1da177e4 LT	179	return ret;
	180	}
	181
	182	if (mtdblk->cache_state == STATE_EMPTY \|\|
	183	mtdblk->cache_offset != sect_start) {
	184	/* fill the cache with the current sector */
	185	mtdblk->cache_state = STATE_EMPTY;
329ad399 AB	186	ret = mtd_read(mtd, sect_start, sect_size,
329ad399 AB	187	&retlen, mtdblk->cache_data);
1da177e4 LT	188	if (ret)
	189	return ret;
	190	if (retlen != sect_size)
	191	return -EIO;
	192
	193	mtdblk->cache_offset = sect_start;
	194	mtdblk->cache_size = sect_size;
	195	mtdblk->cache_state = STATE_CLEAN;
	196	}
	197
	198	/* write data to our local cache */
	199	memcpy (mtdblk->cache_data + offset, buf, size);
	200	mtdblk->cache_state = STATE_DIRTY;
	201	}
	202
	203	buf += size;
	204	pos += size;
	205	len -= size;
	206	}
	207
	208	return 0;
	209	}
	210
	211
97894cda	212	static int do_cached_read (struct mtdblk_dev *mtdblk, unsigned long pos,
1da177e4 LT	213	int len, char *buf)
1da177e4 LT	214	{
cbfe93e9	215	struct mtd_info *mtd = mtdblk->mbd.mtd;
1da177e4 LT	216	unsigned int sect_size = mtdblk->cache_size;
	217	size_t retlen;
	218	int ret;
	219
289c0522	220	pr_debug("mtdblock: read on \"%s\" at 0x%lx, size 0x%x\n",
1da177e4	221	mtd->name, pos, len);
97894cda	222
1da177e4	223	if (!sect_size)
329ad399	224	return mtd_read(mtd, pos, len, &retlen, buf);
1da177e4 LT	225
	226	while (len > 0) {
	227	unsigned long sect_start = (pos/sect_size)*sect_size;
	228	unsigned int offset = pos - sect_start;
	229	unsigned int size = sect_size - offset;
97894cda	230	if (size > len)
1da177e4 LT	231	size = len;
	232
	233	/*
	234	* Check if the requested data is already cached
	235	* Read the requested amount of data from our internal cache if it
	236	* contains what we want, otherwise we read the data directly
	237	* from flash.
	238	*/
	239	if (mtdblk->cache_state != STATE_EMPTY &&
	240	mtdblk->cache_offset == sect_start) {
	241	memcpy (buf, mtdblk->cache_data + offset, size);
	242	} else {
329ad399	243	ret = mtd_read(mtd, pos, size, &retlen, buf);
1da177e4 LT	244	if (ret)
	245	return ret;
	246	if (retlen != size)
	247	return -EIO;
	248	}
	249
	250	buf += size;
	251	pos += size;
	252	len -= size;
	253	}
	254
	255	return 0;
	256	}
	257
	258	static int mtdblock_readsect(struct mtd_blktrans_dev *dev,
	259	unsigned long block, char *buf)
	260	{
cbfe93e9	261	struct mtdblk_dev *mtdblk = container_of(dev, struct mtdblk_dev, mbd);
1da177e4 LT	262	return do_cached_read(mtdblk, block<<9, 512, buf);
	263	}
	264
	265	static int mtdblock_writesect(struct mtd_blktrans_dev *dev,
	266	unsigned long block, char *buf)
	267	{
cbfe93e9	268	struct mtdblk_dev *mtdblk = container_of(dev, struct mtdblk_dev, mbd);
1da177e4	269	if (unlikely(!mtdblk->cache_data && mtdblk->cache_size)) {
cbfe93e9	270	mtdblk->cache_data = vmalloc(mtdblk->mbd.mtd->erasesize);
1da177e4 LT	271	if (!mtdblk->cache_data)
	272	return -EINTR;
	273	/* -EINTR is not really correct, but it is the best match
	274	* documented in man 2 write for all cases. We could also
	275	* return -EAGAIN sometimes, but why bother?
	276	*/
	277	}
	278	return do_cached_write(mtdblk, block<<9, 512, buf);
	279	}
	280
	281	static int mtdblock_open(struct mtd_blktrans_dev *mbd)
	282	{
cbfe93e9	283	struct mtdblk_dev *mtdblk = container_of(mbd, struct mtdblk_dev, mbd);
1da177e4	284
289c0522	285	pr_debug("mtdblock_open\n");
97894cda	286
cbfe93e9 BH	287	if (mtdblk->count) {
cbfe93e9 BH	288	mtdblk->count++;
1da177e4 LT	289	return 0;
1da177e4 LT	290	}
97894cda	291
1da177e4	292	/* OK, it's not open. Create cache info for it */
1da177e4	293	mtdblk->count = 1;
48b19268	294	mutex_init(&mtdblk->cache_mutex);
1da177e4	295	mtdblk->cache_state = STATE_EMPTY;
cbfe93e9 BH	296	if (!(mbd->mtd->flags & MTD_NO_ERASE) && mbd->mtd->erasesize) {
cbfe93e9 BH	297	mtdblk->cache_size = mbd->mtd->erasesize;
1da177e4 LT	298	mtdblk->cache_data = NULL;
	299	}
	300
289c0522	301	pr_debug("ok\n");
1da177e4 LT	302
	303	return 0;
	304	}
	305
a8ca889e	306	static void mtdblock_release(struct mtd_blktrans_dev *mbd)
1da177e4	307	{
cbfe93e9	308	struct mtdblk_dev *mtdblk = container_of(mbd, struct mtdblk_dev, mbd);
1da177e4	309
289c0522	310	pr_debug("mtdblock_release\n");
1da177e4	311
48b19268	312	mutex_lock(&mtdblk->cache_mutex);
1da177e4	313	write_cached_data(mtdblk);
48b19268	314	mutex_unlock(&mtdblk->cache_mutex);
1da177e4 LT	315
1da177e4 LT	316	if (!--mtdblk->count) {
70d5098a AS	317	/*
	318	* It was the last usage. Free the cache, but only sync if
	319	* opened for writing.
	320	*/
	321	if (mbd->file_mode & FMODE_WRITE)
	322	mtd_sync(mbd->mtd);
1da177e4	323	vfree(mtdblk->cache_data);
1da177e4	324	}
d676c117	325
289c0522	326	pr_debug("ok\n");
97894cda	327	}
1da177e4 LT	328
	329	static int mtdblock_flush(struct mtd_blktrans_dev *dev)
	330	{
cbfe93e9	331	struct mtdblk_dev *mtdblk = container_of(dev, struct mtdblk_dev, mbd);
1da177e4	332
48b19268	333	mutex_lock(&mtdblk->cache_mutex);
1da177e4	334	write_cached_data(mtdblk);
48b19268	335	mutex_unlock(&mtdblk->cache_mutex);
327cf292	336	mtd_sync(dev->mtd);
1da177e4 LT	337	return 0;
	338	}
	339
	340	static void mtdblock_add_mtd(struct mtd_blktrans_ops tr, struct mtd_info mtd)
	341	{
cbfe93e9	342	struct mtdblk_dev dev = kzalloc(sizeof(dev), GFP_KERNEL);
1da177e4 LT	343
	344	if (!dev)
	345	return;
	346
cbfe93e9 BH	347	dev->mbd.mtd = mtd;
cbfe93e9 BH	348	dev->mbd.devnum = mtd->index;
19187672	349
cbfe93e9 BH	350	dev->mbd.size = mtd->size >> 9;
cbfe93e9 BH	351	dev->mbd.tr = tr;
1da177e4 LT	352
1da177e4 LT	353	if (!(mtd->flags & MTD_WRITEABLE))
cbfe93e9	354	dev->mbd.readonly = 1;
1da177e4	355
298304f1 ML	356	if (add_mtd_blktrans_dev(&dev->mbd))
298304f1 ML	357	kfree(dev);
1da177e4 LT	358	}
	359
	360	static void mtdblock_remove_dev(struct mtd_blktrans_dev *dev)
	361	{
	362	del_mtd_blktrans_dev(dev);
1da177e4 LT	363	}
	364
	365	static struct mtd_blktrans_ops mtdblock_tr = {
	366	.name = "mtdblock",
2aabeb20	367	.major = MTD_BLOCK_MAJOR,
1da177e4	368	.part_bits = 0,
19187672	369	.blksize = 512,
1da177e4 LT	370	.open = mtdblock_open,
	371	.flush = mtdblock_flush,
	372	.release = mtdblock_release,
	373	.readsect = mtdblock_readsect,
	374	.writesect = mtdblock_writesect,
	375	.add_mtd = mtdblock_add_mtd,
	376	.remove_dev = mtdblock_remove_dev,
	377	.owner = THIS_MODULE,
	378	};
	379
	380	static int __init init_mtdblock(void)
	381	{
	382	return register_mtd_blktrans(&mtdblock_tr);
	383	}
	384
	385	static void __exit cleanup_mtdblock(void)
	386	{
	387	deregister_mtd_blktrans(&mtdblock_tr);
	388	}
	389
	390	module_init(init_mtdblock);
	391	module_exit(cleanup_mtdblock);
	392
	393
	394	MODULE_LICENSE("GPL");
2f82af08	395	MODULE_AUTHOR("Nicolas Pitre <nico@fluxnic.net> et al.");
1da177e4	396	MODULE_DESCRIPTION("Caching read/erase/writeback block device emulation access to MTD devices");