[deliverable/linux.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;
};

static DEFINE_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, 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");

	mutex_lock(&mtdblks_lock);
	if (mtdblk->count) {
		mtdblk->count++;
		mutex_unlock(&mtdblks_lock);
		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;
	}

	mutex_unlock(&mtdblks_lock);

	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(&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 cache, but only sync if
		 * opened for writing.
		 */
		if (mbd->file_mode & FMODE_WRITE)
			mtd_sync(mbd->mtd);
		vfree(mtdblk->cache_data);
	}

	mutex_unlock(&mtdblks_lock);

	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	47
7578ca92	48	static DEFINE_MUTEX(mtdblks_lock);
d676c117	49
1da177e4 LT	50	/*
1da177e4 LT	51	* Cache stuff...
97894cda	52	*
1da177e4 LT	53	* Since typical flash erasable sectors are much larger than what Linux's
	54	* buffer cache can handle, we must implement read-modify-write on flash
	55	* sectors for each block write requests. To avoid over-erasing flash sectors
	56	* and to speed things up, we locally cache a whole flash sector while it is
	57	* being written to until a different sector is required.
	58	*/
	59
	60	static void erase_callback(struct erase_info *done)
	61	{
	62	wait_queue_head_t wait_q = (wait_queue_head_t )done->priv;
	63	wake_up(wait_q);
	64	}
	65
97894cda	66	static int erase_write (struct mtd_info *mtd, unsigned long pos,
1da177e4 LT	67	int len, const char *buf)
	68	{
	69	struct erase_info erase;
	70	DECLARE_WAITQUEUE(wait, current);
	71	wait_queue_head_t wait_q;
	72	size_t retlen;
	73	int ret;
	74
	75	/*
	76	* First, let's erase the flash block.
	77	*/
	78
	79	init_waitqueue_head(&wait_q);
	80	erase.mtd = mtd;
	81	erase.callback = erase_callback;
	82	erase.addr = pos;
	83	erase.len = len;
	84	erase.priv = (u_long)&wait_q;
	85
	86	set_current_state(TASK_INTERRUPTIBLE);
	87	add_wait_queue(&wait_q, &wait);
	88
7e1f0dc0	89	ret = mtd_erase(mtd, &erase);
1da177e4 LT	90	if (ret) {
	91	set_current_state(TASK_RUNNING);
	92	remove_wait_queue(&wait_q, &wait);
	93	printk (KERN_WARNING "mtdblock: erase of region [0x%lx, 0x%x] "
	94	"on \"%s\" failed\n",
	95	pos, len, mtd->name);
	96	return ret;
	97	}
	98
	99	schedule(); /* Wait for erase to finish. */
	100	remove_wait_queue(&wait_q, &wait);
	101
	102	/*
dff15509	103	* Next, write the data to flash.
1da177e4 LT	104	*/
1da177e4 LT	105
eda95cbf	106	ret = mtd_write(mtd, pos, len, &retlen, buf);
1da177e4 LT	107	if (ret)
	108	return ret;
	109	if (retlen != len)
	110	return -EIO;
	111	return 0;
	112	}
	113
	114
	115	static int write_cached_data (struct mtdblk_dev *mtdblk)
	116	{
cbfe93e9	117	struct mtd_info *mtd = mtdblk->mbd.mtd;
1da177e4 LT	118	int ret;
	119
	120	if (mtdblk->cache_state != STATE_DIRTY)
	121	return 0;
	122
289c0522	123	pr_debug("mtdblock: writing cached data for \"%s\" "
97894cda	124	"at 0x%lx, size 0x%x\n", mtd->name,
1da177e4	125	mtdblk->cache_offset, mtdblk->cache_size);
97894cda TG	126
97894cda TG	127	ret = erase_write (mtd, mtdblk->cache_offset,
1da177e4 LT	128	mtdblk->cache_size, mtdblk->cache_data);
	129	if (ret)
	130	return ret;
	131
	132	/*
25985edc	133	* Here we could arguably set the cache state to STATE_CLEAN.
97894cda TG	134	* However this could lead to inconsistency since we will not
97894cda TG	135	* be notified if this content is altered on the flash by other
1da177e4 LT	136	* means. Let's declare it empty and leave buffering tasks to
	137	* the buffer cache instead.
	138	*/
	139	mtdblk->cache_state = STATE_EMPTY;
	140	return 0;
	141	}
	142
	143
97894cda	144	static int do_cached_write (struct mtdblk_dev *mtdblk, unsigned long pos,
1da177e4 LT	145	int len, const char *buf)
1da177e4 LT	146	{
cbfe93e9	147	struct mtd_info *mtd = mtdblk->mbd.mtd;
1da177e4 LT	148	unsigned int sect_size = mtdblk->cache_size;
	149	size_t retlen;
	150	int ret;
	151
289c0522	152	pr_debug("mtdblock: write on \"%s\" at 0x%lx, size 0x%x\n",
1da177e4	153	mtd->name, pos, len);
97894cda	154
1da177e4	155	if (!sect_size)
eda95cbf	156	return mtd_write(mtd, pos, len, &retlen, buf);
1da177e4 LT	157
	158	while (len > 0) {
	159	unsigned long sect_start = (pos/sect_size)*sect_size;
	160	unsigned int offset = pos - sect_start;
	161	unsigned int size = sect_size - offset;
97894cda	162	if( size > len )
1da177e4 LT	163	size = len;
	164
	165	if (size == sect_size) {
97894cda	166	/*
1da177e4 LT	167	* We are covering a whole sector. Thus there is no
	168	* need to bother with the cache while it may still be
	169	* useful for other partial writes.
	170	*/
	171	ret = erase_write (mtd, pos, size, buf);
	172	if (ret)
	173	return ret;
	174	} else {
	175	/* Partial sector: need to use the cache */
	176
	177	if (mtdblk->cache_state == STATE_DIRTY &&
	178	mtdblk->cache_offset != sect_start) {
	179	ret = write_cached_data(mtdblk);
97894cda	180	if (ret)
1da177e4 LT	181	return ret;
	182	}
	183
	184	if (mtdblk->cache_state == STATE_EMPTY \|\|
	185	mtdblk->cache_offset != sect_start) {
	186	/* fill the cache with the current sector */
	187	mtdblk->cache_state = STATE_EMPTY;
329ad399 AB	188	ret = mtd_read(mtd, sect_start, sect_size,
329ad399 AB	189	&retlen, mtdblk->cache_data);
1da177e4 LT	190	if (ret)
	191	return ret;
	192	if (retlen != sect_size)
	193	return -EIO;
	194
	195	mtdblk->cache_offset = sect_start;
	196	mtdblk->cache_size = sect_size;
	197	mtdblk->cache_state = STATE_CLEAN;
	198	}
	199
	200	/* write data to our local cache */
	201	memcpy (mtdblk->cache_data + offset, buf, size);
	202	mtdblk->cache_state = STATE_DIRTY;
	203	}
	204
	205	buf += size;
	206	pos += size;
	207	len -= size;
	208	}
	209
	210	return 0;
	211	}
	212
	213
97894cda	214	static int do_cached_read (struct mtdblk_dev *mtdblk, unsigned long pos,
1da177e4 LT	215	int len, char *buf)
1da177e4 LT	216	{
cbfe93e9	217	struct mtd_info *mtd = mtdblk->mbd.mtd;
1da177e4 LT	218	unsigned int sect_size = mtdblk->cache_size;
	219	size_t retlen;
	220	int ret;
	221
289c0522	222	pr_debug("mtdblock: read on \"%s\" at 0x%lx, size 0x%x\n",
1da177e4	223	mtd->name, pos, len);
97894cda	224
1da177e4	225	if (!sect_size)
329ad399	226	return mtd_read(mtd, pos, len, &retlen, buf);
1da177e4 LT	227
	228	while (len > 0) {
	229	unsigned long sect_start = (pos/sect_size)*sect_size;
	230	unsigned int offset = pos - sect_start;
	231	unsigned int size = sect_size - offset;
97894cda	232	if (size > len)
1da177e4 LT	233	size = len;
	234
	235	/*
	236	* Check if the requested data is already cached
	237	* Read the requested amount of data from our internal cache if it
	238	* contains what we want, otherwise we read the data directly
	239	* from flash.
	240	*/
	241	if (mtdblk->cache_state != STATE_EMPTY &&
	242	mtdblk->cache_offset == sect_start) {
	243	memcpy (buf, mtdblk->cache_data + offset, size);
	244	} else {
329ad399	245	ret = mtd_read(mtd, pos, size, &retlen, buf);
1da177e4 LT	246	if (ret)
	247	return ret;
	248	if (retlen != size)
	249	return -EIO;
	250	}
	251
	252	buf += size;
	253	pos += size;
	254	len -= size;
	255	}
	256
	257	return 0;
	258	}
	259
	260	static int mtdblock_readsect(struct mtd_blktrans_dev *dev,
	261	unsigned long block, char *buf)
	262	{
cbfe93e9	263	struct mtdblk_dev *mtdblk = container_of(dev, struct mtdblk_dev, mbd);
1da177e4 LT	264	return do_cached_read(mtdblk, block<<9, 512, buf);
	265	}
	266
	267	static int mtdblock_writesect(struct mtd_blktrans_dev *dev,
	268	unsigned long block, char *buf)
	269	{
cbfe93e9	270	struct mtdblk_dev *mtdblk = container_of(dev, struct mtdblk_dev, mbd);
1da177e4	271	if (unlikely(!mtdblk->cache_data && mtdblk->cache_size)) {
cbfe93e9	272	mtdblk->cache_data = vmalloc(mtdblk->mbd.mtd->erasesize);
1da177e4 LT	273	if (!mtdblk->cache_data)
	274	return -EINTR;
	275	/* -EINTR is not really correct, but it is the best match
	276	* documented in man 2 write for all cases. We could also
	277	* return -EAGAIN sometimes, but why bother?
	278	*/
	279	}
	280	return do_cached_write(mtdblk, block<<9, 512, buf);
	281	}
	282
	283	static int mtdblock_open(struct mtd_blktrans_dev *mbd)
	284	{
cbfe93e9	285	struct mtdblk_dev *mtdblk = container_of(mbd, struct mtdblk_dev, mbd);
1da177e4	286
289c0522	287	pr_debug("mtdblock_open\n");
97894cda	288
d676c117	289	mutex_lock(&mtdblks_lock);
cbfe93e9 BH	290	if (mtdblk->count) {
cbfe93e9 BH	291	mtdblk->count++;
d676c117	292	mutex_unlock(&mtdblks_lock);
1da177e4 LT	293	return 0;
1da177e4 LT	294	}
97894cda	295
1da177e4	296	/* OK, it's not open. Create cache info for it */
1da177e4	297	mtdblk->count = 1;
48b19268	298	mutex_init(&mtdblk->cache_mutex);
1da177e4	299	mtdblk->cache_state = STATE_EMPTY;
cbfe93e9 BH	300	if (!(mbd->mtd->flags & MTD_NO_ERASE) && mbd->mtd->erasesize) {
cbfe93e9 BH	301	mtdblk->cache_size = mbd->mtd->erasesize;
1da177e4 LT	302	mtdblk->cache_data = NULL;
	303	}
	304
d676c117	305	mutex_unlock(&mtdblks_lock);
97894cda	306
289c0522	307	pr_debug("ok\n");
1da177e4 LT	308
	309	return 0;
	310	}
	311
a8ca889e	312	static void mtdblock_release(struct mtd_blktrans_dev *mbd)
1da177e4	313	{
cbfe93e9	314	struct mtdblk_dev *mtdblk = container_of(mbd, struct mtdblk_dev, mbd);
1da177e4	315
289c0522	316	pr_debug("mtdblock_release\n");
1da177e4	317
d676c117 MK	318	mutex_lock(&mtdblks_lock);
d676c117 MK	319
48b19268	320	mutex_lock(&mtdblk->cache_mutex);
1da177e4	321	write_cached_data(mtdblk);
48b19268	322	mutex_unlock(&mtdblk->cache_mutex);
1da177e4 LT	323
1da177e4 LT	324	if (!--mtdblk->count) {
70d5098a AS	325	/*
	326	* It was the last usage. Free the cache, but only sync if
	327	* opened for writing.
	328	*/
	329	if (mbd->file_mode & FMODE_WRITE)
	330	mtd_sync(mbd->mtd);
1da177e4	331	vfree(mtdblk->cache_data);
1da177e4	332	}
d676c117 MK	333
	334	mutex_unlock(&mtdblks_lock);
	335
289c0522	336	pr_debug("ok\n");
97894cda	337	}
1da177e4 LT	338
	339	static int mtdblock_flush(struct mtd_blktrans_dev *dev)
	340	{
cbfe93e9	341	struct mtdblk_dev *mtdblk = container_of(dev, struct mtdblk_dev, mbd);
1da177e4	342
48b19268	343	mutex_lock(&mtdblk->cache_mutex);
1da177e4	344	write_cached_data(mtdblk);
48b19268	345	mutex_unlock(&mtdblk->cache_mutex);
327cf292	346	mtd_sync(dev->mtd);
1da177e4 LT	347	return 0;
	348	}
	349
	350	static void mtdblock_add_mtd(struct mtd_blktrans_ops tr, struct mtd_info mtd)
	351	{
cbfe93e9	352	struct mtdblk_dev dev = kzalloc(sizeof(dev), GFP_KERNEL);
1da177e4 LT	353
	354	if (!dev)
	355	return;
	356
cbfe93e9 BH	357	dev->mbd.mtd = mtd;
cbfe93e9 BH	358	dev->mbd.devnum = mtd->index;
19187672	359
cbfe93e9 BH	360	dev->mbd.size = mtd->size >> 9;
cbfe93e9 BH	361	dev->mbd.tr = tr;
1da177e4 LT	362
1da177e4 LT	363	if (!(mtd->flags & MTD_WRITEABLE))
cbfe93e9	364	dev->mbd.readonly = 1;
1da177e4	365
298304f1 ML	366	if (add_mtd_blktrans_dev(&dev->mbd))
298304f1 ML	367	kfree(dev);
1da177e4 LT	368	}
	369
	370	static void mtdblock_remove_dev(struct mtd_blktrans_dev *dev)
	371	{
	372	del_mtd_blktrans_dev(dev);
1da177e4 LT	373	}
	374
	375	static struct mtd_blktrans_ops mtdblock_tr = {
	376	.name = "mtdblock",
2aabeb20	377	.major = MTD_BLOCK_MAJOR,
1da177e4	378	.part_bits = 0,
19187672	379	.blksize = 512,
1da177e4 LT	380	.open = mtdblock_open,
	381	.flush = mtdblock_flush,
	382	.release = mtdblock_release,
	383	.readsect = mtdblock_readsect,
	384	.writesect = mtdblock_writesect,
	385	.add_mtd = mtdblock_add_mtd,
	386	.remove_dev = mtdblock_remove_dev,
	387	.owner = THIS_MODULE,
	388	};
	389
	390	static int __init init_mtdblock(void)
	391	{
	392	return register_mtd_blktrans(&mtdblock_tr);
	393	}
	394
	395	static void __exit cleanup_mtdblock(void)
	396	{
	397	deregister_mtd_blktrans(&mtdblock_tr);
	398	}
	399
	400	module_init(init_mtdblock);
	401	module_exit(cleanup_mtdblock);
	402
	403
	404	MODULE_LICENSE("GPL");
2f82af08	405	MODULE_AUTHOR("Nicolas Pitre <nico@fluxnic.net> et al.");
1da177e4	406	MODULE_DESCRIPTION("Caching read/erase/writeback block device emulation access to MTD devices");