[linux-2.6-block.git] / drivers / mtd / mtdblock.c

/*
 * Direct MTD block device access
 *
 * $Id: mtdblock.c,v 1.68 2005/11/07 11:14:20 gleixner Exp $
 *
 * (C) 2000-2003 Nicolas Pitre <nico@cam.org>
 * (C) 1999-2003 David Woodhouse <dwmw2@infradead.org>
 */

#include <linux/config.h>
#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>

static struct mtdblk_dev {
	struct mtd_info *mtd;
	int count;
	struct semaphore cache_sem;
	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];

/*
 * 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");

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

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

	memset(mtdblk, 0, sizeof(*mtdblk));
	mtdblk->count = 1;
	mtdblk->mtd = mtd;

	init_MUTEX (&mtdblk->cache_sem);
	mtdblk->cache_state = STATE_EMPTY;
	if ((mtdblk->mtd->flags & MTD_CAP_RAM) != MTD_CAP_RAM &&
	    mtdblk->mtd->erasesize) {
		mtdblk->cache_size = mtdblk->mtd->erasesize;
		mtdblk->cache_data = NULL;
	}

	mtdblks[dev] = mtdblk;

	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");

	down(&mtdblk->cache_sem);
	write_cached_data(mtdblk);
	up(&mtdblk->cache_sem);

	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);
	}
	DEBUG(MTD_DEBUG_LEVEL1, "ok\n");

	return 0;
}

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

	down(&mtdblk->cache_sem);
	write_cached_data(mtdblk);
	up(&mtdblk->cache_sem);

	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 = kmalloc(sizeof(*dev), GFP_KERNEL);

	if (!dev)
		return;

	memset(dev, 0, sizeof(*dev));

	dev->mtd = mtd;
	dev->devnum = mtd->index;
	dev->blksize = 512;
	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,
	.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@cam.org> 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	*
97894cda	4	* $Id: mtdblock.c,v 1.68 2005/11/07 11:14:20 gleixner Exp $
1da177e4 LT	5	*
	6	* (C) 2000-2003 Nicolas Pitre <nico@cam.org>
	7	* (C) 1999-2003 David Woodhouse <dwmw2@infradead.org>
	8	*/
	9
	10	#include <linux/config.h>
1da177e4 LT	11	#include <linux/fs.h>
1da177e4 LT	12	#include <linux/init.h>
15fdc52f TG	13	#include <linux/kernel.h>
	14	#include <linux/module.h>
	15	#include <linux/sched.h>
1da177e4	16	#include <linux/slab.h>
15fdc52f	17	#include <linux/types.h>
1da177e4	18	#include <linux/vmalloc.h>
15fdc52f	19
1da177e4 LT	20	#include <linux/mtd/mtd.h>
	21	#include <linux/mtd/blktrans.h>
	22
	23	static struct mtdblk_dev {
	24	struct mtd_info *mtd;
	25	int count;
	26	struct semaphore cache_sem;
	27	unsigned char *cache_data;
	28	unsigned long cache_offset;
	29	unsigned int cache_size;
	30	enum { STATE_EMPTY, STATE_CLEAN, STATE_DIRTY } cache_state;
	31	} *mtdblks[MAX_MTD_DEVICES];
	32
	33	/*
	34	* Cache stuff...
97894cda	35	*
1da177e4 LT	36	* Since typical flash erasable sectors are much larger than what Linux's
	37	* buffer cache can handle, we must implement read-modify-write on flash
	38	* sectors for each block write requests. To avoid over-erasing flash sectors
	39	* and to speed things up, we locally cache a whole flash sector while it is
	40	* being written to until a different sector is required.
	41	*/
	42
	43	static void erase_callback(struct erase_info *done)
	44	{
	45	wait_queue_head_t wait_q = (wait_queue_head_t )done->priv;
	46	wake_up(wait_q);
	47	}
	48
97894cda	49	static int erase_write (struct mtd_info *mtd, unsigned long pos,
1da177e4 LT	50	int len, const char *buf)
	51	{
	52	struct erase_info erase;
	53	DECLARE_WAITQUEUE(wait, current);
	54	wait_queue_head_t wait_q;
	55	size_t retlen;
	56	int ret;
	57
	58	/*
	59	* First, let's erase the flash block.
	60	*/
	61
	62	init_waitqueue_head(&wait_q);
	63	erase.mtd = mtd;
	64	erase.callback = erase_callback;
	65	erase.addr = pos;
	66	erase.len = len;
	67	erase.priv = (u_long)&wait_q;
	68
	69	set_current_state(TASK_INTERRUPTIBLE);
	70	add_wait_queue(&wait_q, &wait);
	71
	72	ret = MTD_ERASE(mtd, &erase);
	73	if (ret) {
	74	set_current_state(TASK_RUNNING);
	75	remove_wait_queue(&wait_q, &wait);
	76	printk (KERN_WARNING "mtdblock: erase of region [0x%lx, 0x%x] "
	77	"on \"%s\" failed\n",
	78	pos, len, mtd->name);
	79	return ret;
	80	}
	81
	82	schedule(); /* Wait for erase to finish. */
	83	remove_wait_queue(&wait_q, &wait);
	84
	85	/*
	86	* Next, writhe data to flash.
	87	*/
	88
	89	ret = MTD_WRITE (mtd, pos, len, &retlen, buf);
	90	if (ret)
	91	return ret;
	92	if (retlen != len)
	93	return -EIO;
	94	return 0;
	95	}
	96
	97
	98	static int write_cached_data (struct mtdblk_dev *mtdblk)
	99	{
	100	struct mtd_info *mtd = mtdblk->mtd;
	101	int ret;
	102
	103	if (mtdblk->cache_state != STATE_DIRTY)
	104	return 0;
	105
	106	DEBUG(MTD_DEBUG_LEVEL2, "mtdblock: writing cached data for \"%s\" "
97894cda	107	"at 0x%lx, size 0x%x\n", mtd->name,
1da177e4	108	mtdblk->cache_offset, mtdblk->cache_size);
97894cda TG	109
97894cda TG	110	ret = erase_write (mtd, mtdblk->cache_offset,
1da177e4 LT	111	mtdblk->cache_size, mtdblk->cache_data);
	112	if (ret)
	113	return ret;
	114
	115	/*
	116	* Here we could argubly set the cache state to STATE_CLEAN.
97894cda TG	117	* However this could lead to inconsistency since we will not
97894cda TG	118	* be notified if this content is altered on the flash by other
1da177e4 LT	119	* means. Let's declare it empty and leave buffering tasks to
	120	* the buffer cache instead.
	121	*/
	122	mtdblk->cache_state = STATE_EMPTY;
	123	return 0;
	124	}
	125
	126
97894cda	127	static int do_cached_write (struct mtdblk_dev *mtdblk, unsigned long pos,
1da177e4 LT	128	int len, const char *buf)
	129	{
	130	struct mtd_info *mtd = mtdblk->mtd;
	131	unsigned int sect_size = mtdblk->cache_size;
	132	size_t retlen;
	133	int ret;
	134
	135	DEBUG(MTD_DEBUG_LEVEL2, "mtdblock: write on \"%s\" at 0x%lx, size 0x%x\n",
	136	mtd->name, pos, len);
97894cda	137
1da177e4 LT	138	if (!sect_size)
	139	return MTD_WRITE (mtd, pos, len, &retlen, buf);
	140
	141	while (len > 0) {
	142	unsigned long sect_start = (pos/sect_size)*sect_size;
	143	unsigned int offset = pos - sect_start;
	144	unsigned int size = sect_size - offset;
97894cda	145	if( size > len )
1da177e4 LT	146	size = len;
	147
	148	if (size == sect_size) {
97894cda	149	/*
1da177e4 LT	150	* We are covering a whole sector. Thus there is no
	151	* need to bother with the cache while it may still be
	152	* useful for other partial writes.
	153	*/
	154	ret = erase_write (mtd, pos, size, buf);
	155	if (ret)
	156	return ret;
	157	} else {
	158	/* Partial sector: need to use the cache */
	159
	160	if (mtdblk->cache_state == STATE_DIRTY &&
	161	mtdblk->cache_offset != sect_start) {
	162	ret = write_cached_data(mtdblk);
97894cda	163	if (ret)
1da177e4 LT	164	return ret;
	165	}
	166
	167	if (mtdblk->cache_state == STATE_EMPTY \|\|
	168	mtdblk->cache_offset != sect_start) {
	169	/* fill the cache with the current sector */
	170	mtdblk->cache_state = STATE_EMPTY;
	171	ret = MTD_READ(mtd, sect_start, sect_size, &retlen, mtdblk->cache_data);
	172	if (ret)
	173	return ret;
	174	if (retlen != sect_size)
	175	return -EIO;
	176
	177	mtdblk->cache_offset = sect_start;
	178	mtdblk->cache_size = sect_size;
	179	mtdblk->cache_state = STATE_CLEAN;
	180	}
	181
	182	/* write data to our local cache */
	183	memcpy (mtdblk->cache_data + offset, buf, size);
	184	mtdblk->cache_state = STATE_DIRTY;
	185	}
	186
	187	buf += size;
	188	pos += size;
	189	len -= size;
	190	}
	191
	192	return 0;
	193	}
	194
	195
97894cda	196	static int do_cached_read (struct mtdblk_dev *mtdblk, unsigned long pos,
1da177e4 LT	197	int len, char *buf)
	198	{
	199	struct mtd_info *mtd = mtdblk->mtd;
	200	unsigned int sect_size = mtdblk->cache_size;
	201	size_t retlen;
	202	int ret;
	203
97894cda	204	DEBUG(MTD_DEBUG_LEVEL2, "mtdblock: read on \"%s\" at 0x%lx, size 0x%x\n",
1da177e4	205	mtd->name, pos, len);
97894cda	206
1da177e4 LT	207	if (!sect_size)
	208	return MTD_READ (mtd, pos, len, &retlen, buf);
	209
	210	while (len > 0) {
	211	unsigned long sect_start = (pos/sect_size)*sect_size;
	212	unsigned int offset = pos - sect_start;
	213	unsigned int size = sect_size - offset;
97894cda	214	if (size > len)
1da177e4 LT	215	size = len;
	216
	217	/*
	218	* Check if the requested data is already cached
	219	* Read the requested amount of data from our internal cache if it
	220	* contains what we want, otherwise we read the data directly
	221	* from flash.
	222	*/
	223	if (mtdblk->cache_state != STATE_EMPTY &&
	224	mtdblk->cache_offset == sect_start) {
	225	memcpy (buf, mtdblk->cache_data + offset, size);
	226	} else {
	227	ret = MTD_READ (mtd, pos, size, &retlen, buf);
	228	if (ret)
	229	return ret;
	230	if (retlen != size)
	231	return -EIO;
	232	}
	233
	234	buf += size;
	235	pos += size;
	236	len -= size;
	237	}
	238
	239	return 0;
	240	}
	241
	242	static int mtdblock_readsect(struct mtd_blktrans_dev *dev,
	243	unsigned long block, char *buf)
	244	{
	245	struct mtdblk_dev *mtdblk = mtdblks[dev->devnum];
	246	return do_cached_read(mtdblk, block<<9, 512, buf);
	247	}
	248
	249	static int mtdblock_writesect(struct mtd_blktrans_dev *dev,
	250	unsigned long block, char *buf)
	251	{
	252	struct mtdblk_dev *mtdblk = mtdblks[dev->devnum];
	253	if (unlikely(!mtdblk->cache_data && mtdblk->cache_size)) {
	254	mtdblk->cache_data = vmalloc(mtdblk->mtd->erasesize);
	255	if (!mtdblk->cache_data)
	256	return -EINTR;
	257	/* -EINTR is not really correct, but it is the best match
	258	* documented in man 2 write for all cases. We could also
	259	* return -EAGAIN sometimes, but why bother?
	260	*/
	261	}
	262	return do_cached_write(mtdblk, block<<9, 512, buf);
	263	}
	264
	265	static int mtdblock_open(struct mtd_blktrans_dev *mbd)
	266	{
	267	struct mtdblk_dev *mtdblk;
	268	struct mtd_info *mtd = mbd->mtd;
	269	int dev = mbd->devnum;
	270
	271	DEBUG(MTD_DEBUG_LEVEL1,"mtdblock_open\n");
97894cda	272
1da177e4 LT	273	if (mtdblks[dev]) {
	274	mtdblks[dev]->count++;
	275	return 0;
	276	}
97894cda	277
1da177e4 LT	278	/* OK, it's not open. Create cache info for it */
	279	mtdblk = kmalloc(sizeof(struct mtdblk_dev), GFP_KERNEL);
	280	if (!mtdblk)
	281	return -ENOMEM;
	282
	283	memset(mtdblk, 0, sizeof(*mtdblk));
	284	mtdblk->count = 1;
	285	mtdblk->mtd = mtd;
	286
	287	init_MUTEX (&mtdblk->cache_sem);
	288	mtdblk->cache_state = STATE_EMPTY;
	289	if ((mtdblk->mtd->flags & MTD_CAP_RAM) != MTD_CAP_RAM &&
	290	mtdblk->mtd->erasesize) {
	291	mtdblk->cache_size = mtdblk->mtd->erasesize;
	292	mtdblk->cache_data = NULL;
	293	}
	294
	295	mtdblks[dev] = mtdblk;
97894cda	296
1da177e4 LT	297	DEBUG(MTD_DEBUG_LEVEL1, "ok\n");
	298
	299	return 0;
	300	}
	301
	302	static int mtdblock_release(struct mtd_blktrans_dev *mbd)
	303	{
	304	int dev = mbd->devnum;
	305	struct mtdblk_dev *mtdblk = mtdblks[dev];
	306
	307	DEBUG(MTD_DEBUG_LEVEL1, "mtdblock_release\n");
	308
	309	down(&mtdblk->cache_sem);
	310	write_cached_data(mtdblk);
	311	up(&mtdblk->cache_sem);
	312
	313	if (!--mtdblk->count) {
	314	/* It was the last usage. Free the device */
	315	mtdblks[dev] = NULL;
	316	if (mtdblk->mtd->sync)
	317	mtdblk->mtd->sync(mtdblk->mtd);
	318	vfree(mtdblk->cache_data);
	319	kfree(mtdblk);
	320	}
	321	DEBUG(MTD_DEBUG_LEVEL1, "ok\n");
	322
	323	return 0;
97894cda	324	}
1da177e4 LT	325
	326	static int mtdblock_flush(struct mtd_blktrans_dev *dev)
	327	{
	328	struct mtdblk_dev *mtdblk = mtdblks[dev->devnum];
	329
	330	down(&mtdblk->cache_sem);
	331	write_cached_data(mtdblk);
	332	up(&mtdblk->cache_sem);
	333
	334	if (mtdblk->mtd->sync)
	335	mtdblk->mtd->sync(mtdblk->mtd);
	336	return 0;
	337	}
	338
	339	static void mtdblock_add_mtd(struct mtd_blktrans_ops tr, struct mtd_info mtd)
	340	{
	341	struct mtd_blktrans_dev dev = kmalloc(sizeof(dev), GFP_KERNEL);
	342
	343	if (!dev)
	344	return;
	345
	346	memset(dev, 0, sizeof(*dev));
	347
	348	dev->mtd = mtd;
	349	dev->devnum = mtd->index;
	350	dev->blksize = 512;
	351	dev->size = mtd->size >> 9;
	352	dev->tr = tr;
	353
	354	if (!(mtd->flags & MTD_WRITEABLE))
	355	dev->readonly = 1;
	356
	357	add_mtd_blktrans_dev(dev);
	358	}
	359
	360	static void mtdblock_remove_dev(struct mtd_blktrans_dev *dev)
	361	{
	362	del_mtd_blktrans_dev(dev);
	363	kfree(dev);
	364	}
	365
	366	static struct mtd_blktrans_ops mtdblock_tr = {
	367	.name = "mtdblock",
	368	.major = 31,
	369	.part_bits = 0,
	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");
395	MODULE_AUTHOR("Nicolas Pitre <nico@cam.org> et al.");
396	MODULE_DESCRIPTION("Caching read/erase/writeback block device emulation access to MTD devices");