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Thomas Gleixner97894cd2005-11-07 11:15:26 +00001/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07002 * Direct MTD block device access
3 *
David Woodhousea1452a32010-08-08 20:58:20 +01004 * 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 *
Linus Torvalds1da177e2005-04-16 15:20:36 -070021 */
22
Linus Torvalds1da177e2005-04-16 15:20:36 -070023#include <linux/fs.h>
24#include <linux/init.h>
Thomas Gleixner15fdc522005-11-07 00:14:42 +010025#include <linux/kernel.h>
26#include <linux/module.h>
27#include <linux/sched.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070028#include <linux/slab.h>
Thomas Gleixner15fdc522005-11-07 00:14:42 +010029#include <linux/types.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070030#include <linux/vmalloc.h>
Thomas Gleixner15fdc522005-11-07 00:14:42 +010031
Linus Torvalds1da177e2005-04-16 15:20:36 -070032#include <linux/mtd/mtd.h>
33#include <linux/mtd/blktrans.h>
Ingo Molnar48b19262006-03-31 02:29:41 -080034#include <linux/mutex.h>
35
Linus Torvalds1da177e2005-04-16 15:20:36 -070036
Ben Hutchingscbfe93e2010-01-29 20:58:37 +000037struct mtdblk_dev {
38 struct mtd_blktrans_dev mbd;
Linus Torvalds1da177e2005-04-16 15:20:36 -070039 int count;
Ingo Molnar48b19262006-03-31 02:29:41 -080040 struct mutex cache_mutex;
Linus Torvalds1da177e2005-04-16 15:20:36 -070041 unsigned char *cache_data;
42 unsigned long cache_offset;
43 unsigned int cache_size;
44 enum { STATE_EMPTY, STATE_CLEAN, STATE_DIRTY } cache_state;
Ben Hutchingscbfe93e2010-01-29 20:58:37 +000045};
Linus Torvalds1da177e2005-04-16 15:20:36 -070046
Axel Lin7578ca92011-06-03 14:10:22 +080047static DEFINE_MUTEX(mtdblks_lock);
Matthias Kaehlcked676c112009-07-14 22:04:29 +020048
Linus Torvalds1da177e2005-04-16 15:20:36 -070049/*
50 * Cache stuff...
Thomas Gleixner97894cd2005-11-07 11:15:26 +000051 *
Linus Torvalds1da177e2005-04-16 15:20:36 -070052 * Since typical flash erasable sectors are much larger than what Linux's
53 * buffer cache can handle, we must implement read-modify-write on flash
54 * sectors for each block write requests. To avoid over-erasing flash sectors
55 * and to speed things up, we locally cache a whole flash sector while it is
56 * being written to until a different sector is required.
57 */
58
59static void erase_callback(struct erase_info *done)
60{
61 wait_queue_head_t *wait_q = (wait_queue_head_t *)done->priv;
62 wake_up(wait_q);
63}
64
Thomas Gleixner97894cd2005-11-07 11:15:26 +000065static int erase_write (struct mtd_info *mtd, unsigned long pos,
Linus Torvalds1da177e2005-04-16 15:20:36 -070066 int len, const char *buf)
67{
68 struct erase_info erase;
69 DECLARE_WAITQUEUE(wait, current);
70 wait_queue_head_t wait_q;
71 size_t retlen;
72 int ret;
73
74 /*
75 * First, let's erase the flash block.
76 */
77
78 init_waitqueue_head(&wait_q);
79 erase.mtd = mtd;
80 erase.callback = erase_callback;
81 erase.addr = pos;
82 erase.len = len;
83 erase.priv = (u_long)&wait_q;
84
85 set_current_state(TASK_INTERRUPTIBLE);
86 add_wait_queue(&wait_q, &wait);
87
Artem Bityutskiy7e1f0dc2011-12-23 15:25:39 +020088 ret = mtd_erase(mtd, &erase);
Linus Torvalds1da177e2005-04-16 15:20:36 -070089 if (ret) {
90 set_current_state(TASK_RUNNING);
91 remove_wait_queue(&wait_q, &wait);
92 printk (KERN_WARNING "mtdblock: erase of region [0x%lx, 0x%x] "
93 "on \"%s\" failed\n",
94 pos, len, mtd->name);
95 return ret;
96 }
97
98 schedule(); /* Wait for erase to finish. */
99 remove_wait_queue(&wait_q, &wait);
100
101 /*
Matthias Kaehlckedff15502009-07-06 12:02:08 +0200102 * Next, write the data to flash.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700103 */
104
Thomas Gleixnerf4a43cf2006-05-28 11:01:53 +0200105 ret = mtd->write(mtd, pos, len, &retlen, buf);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700106 if (ret)
107 return ret;
108 if (retlen != len)
109 return -EIO;
110 return 0;
111}
112
113
114static int write_cached_data (struct mtdblk_dev *mtdblk)
115{
Ben Hutchingscbfe93e2010-01-29 20:58:37 +0000116 struct mtd_info *mtd = mtdblk->mbd.mtd;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700117 int ret;
118
119 if (mtdblk->cache_state != STATE_DIRTY)
120 return 0;
121
Brian Norris289c0522011-07-19 10:06:09 -0700122 pr_debug("mtdblock: writing cached data for \"%s\" "
Thomas Gleixner97894cd2005-11-07 11:15:26 +0000123 "at 0x%lx, size 0x%x\n", mtd->name,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700124 mtdblk->cache_offset, mtdblk->cache_size);
Thomas Gleixner97894cd2005-11-07 11:15:26 +0000125
126 ret = erase_write (mtd, mtdblk->cache_offset,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700127 mtdblk->cache_size, mtdblk->cache_data);
128 if (ret)
129 return ret;
130
131 /*
Lucas De Marchi25985ed2011-03-30 22:57:33 -0300132 * Here we could arguably set the cache state to STATE_CLEAN.
Thomas Gleixner97894cd2005-11-07 11:15:26 +0000133 * However this could lead to inconsistency since we will not
134 * be notified if this content is altered on the flash by other
Linus Torvalds1da177e2005-04-16 15:20:36 -0700135 * means. Let's declare it empty and leave buffering tasks to
136 * the buffer cache instead.
137 */
138 mtdblk->cache_state = STATE_EMPTY;
139 return 0;
140}
141
142
Thomas Gleixner97894cd2005-11-07 11:15:26 +0000143static int do_cached_write (struct mtdblk_dev *mtdblk, unsigned long pos,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700144 int len, const char *buf)
145{
Ben Hutchingscbfe93e2010-01-29 20:58:37 +0000146 struct mtd_info *mtd = mtdblk->mbd.mtd;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700147 unsigned int sect_size = mtdblk->cache_size;
148 size_t retlen;
149 int ret;
150
Brian Norris289c0522011-07-19 10:06:09 -0700151 pr_debug("mtdblock: write on \"%s\" at 0x%lx, size 0x%x\n",
Linus Torvalds1da177e2005-04-16 15:20:36 -0700152 mtd->name, pos, len);
Thomas Gleixner97894cd2005-11-07 11:15:26 +0000153
Linus Torvalds1da177e2005-04-16 15:20:36 -0700154 if (!sect_size)
Thomas Gleixnerf4a43cf2006-05-28 11:01:53 +0200155 return mtd->write(mtd, pos, len, &retlen, buf);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700156
157 while (len > 0) {
158 unsigned long sect_start = (pos/sect_size)*sect_size;
159 unsigned int offset = pos - sect_start;
160 unsigned int size = sect_size - offset;
Thomas Gleixner97894cd2005-11-07 11:15:26 +0000161 if( size > len )
Linus Torvalds1da177e2005-04-16 15:20:36 -0700162 size = len;
163
164 if (size == sect_size) {
Thomas Gleixner97894cd2005-11-07 11:15:26 +0000165 /*
Linus Torvalds1da177e2005-04-16 15:20:36 -0700166 * We are covering a whole sector. Thus there is no
167 * need to bother with the cache while it may still be
168 * useful for other partial writes.
169 */
170 ret = erase_write (mtd, pos, size, buf);
171 if (ret)
172 return ret;
173 } else {
174 /* Partial sector: need to use the cache */
175
176 if (mtdblk->cache_state == STATE_DIRTY &&
177 mtdblk->cache_offset != sect_start) {
178 ret = write_cached_data(mtdblk);
Thomas Gleixner97894cd2005-11-07 11:15:26 +0000179 if (ret)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700180 return ret;
181 }
182
183 if (mtdblk->cache_state == STATE_EMPTY ||
184 mtdblk->cache_offset != sect_start) {
185 /* fill the cache with the current sector */
186 mtdblk->cache_state = STATE_EMPTY;
Thomas Gleixnerf4a43cf2006-05-28 11:01:53 +0200187 ret = mtd->read(mtd, sect_start, sect_size,
188 &retlen, mtdblk->cache_data);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700189 if (ret)
190 return ret;
191 if (retlen != sect_size)
192 return -EIO;
193
194 mtdblk->cache_offset = sect_start;
195 mtdblk->cache_size = sect_size;
196 mtdblk->cache_state = STATE_CLEAN;
197 }
198
199 /* write data to our local cache */
200 memcpy (mtdblk->cache_data + offset, buf, size);
201 mtdblk->cache_state = STATE_DIRTY;
202 }
203
204 buf += size;
205 pos += size;
206 len -= size;
207 }
208
209 return 0;
210}
211
212
Thomas Gleixner97894cd2005-11-07 11:15:26 +0000213static int do_cached_read (struct mtdblk_dev *mtdblk, unsigned long pos,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700214 int len, char *buf)
215{
Ben Hutchingscbfe93e2010-01-29 20:58:37 +0000216 struct mtd_info *mtd = mtdblk->mbd.mtd;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700217 unsigned int sect_size = mtdblk->cache_size;
218 size_t retlen;
219 int ret;
220
Brian Norris289c0522011-07-19 10:06:09 -0700221 pr_debug("mtdblock: read on \"%s\" at 0x%lx, size 0x%x\n",
Linus Torvalds1da177e2005-04-16 15:20:36 -0700222 mtd->name, pos, len);
Thomas Gleixner97894cd2005-11-07 11:15:26 +0000223
Linus Torvalds1da177e2005-04-16 15:20:36 -0700224 if (!sect_size)
Thomas Gleixnerf4a43cf2006-05-28 11:01:53 +0200225 return mtd->read(mtd, pos, len, &retlen, buf);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700226
227 while (len > 0) {
228 unsigned long sect_start = (pos/sect_size)*sect_size;
229 unsigned int offset = pos - sect_start;
230 unsigned int size = sect_size - offset;
Thomas Gleixner97894cd2005-11-07 11:15:26 +0000231 if (size > len)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700232 size = len;
233
234 /*
235 * Check if the requested data is already cached
236 * Read the requested amount of data from our internal cache if it
237 * contains what we want, otherwise we read the data directly
238 * from flash.
239 */
240 if (mtdblk->cache_state != STATE_EMPTY &&
241 mtdblk->cache_offset == sect_start) {
242 memcpy (buf, mtdblk->cache_data + offset, size);
243 } else {
Thomas Gleixnerf4a43cf2006-05-28 11:01:53 +0200244 ret = mtd->read(mtd, pos, size, &retlen, buf);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700245 if (ret)
246 return ret;
247 if (retlen != size)
248 return -EIO;
249 }
250
251 buf += size;
252 pos += size;
253 len -= size;
254 }
255
256 return 0;
257}
258
259static int mtdblock_readsect(struct mtd_blktrans_dev *dev,
260 unsigned long block, char *buf)
261{
Ben Hutchingscbfe93e2010-01-29 20:58:37 +0000262 struct mtdblk_dev *mtdblk = container_of(dev, struct mtdblk_dev, mbd);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700263 return do_cached_read(mtdblk, block<<9, 512, buf);
264}
265
266static int mtdblock_writesect(struct mtd_blktrans_dev *dev,
267 unsigned long block, char *buf)
268{
Ben Hutchingscbfe93e2010-01-29 20:58:37 +0000269 struct mtdblk_dev *mtdblk = container_of(dev, struct mtdblk_dev, mbd);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700270 if (unlikely(!mtdblk->cache_data && mtdblk->cache_size)) {
Ben Hutchingscbfe93e2010-01-29 20:58:37 +0000271 mtdblk->cache_data = vmalloc(mtdblk->mbd.mtd->erasesize);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700272 if (!mtdblk->cache_data)
273 return -EINTR;
274 /* -EINTR is not really correct, but it is the best match
275 * documented in man 2 write for all cases. We could also
276 * return -EAGAIN sometimes, but why bother?
277 */
278 }
279 return do_cached_write(mtdblk, block<<9, 512, buf);
280}
281
282static int mtdblock_open(struct mtd_blktrans_dev *mbd)
283{
Ben Hutchingscbfe93e2010-01-29 20:58:37 +0000284 struct mtdblk_dev *mtdblk = container_of(mbd, struct mtdblk_dev, mbd);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700285
Brian Norris289c0522011-07-19 10:06:09 -0700286 pr_debug("mtdblock_open\n");
Thomas Gleixner97894cd2005-11-07 11:15:26 +0000287
Matthias Kaehlcked676c112009-07-14 22:04:29 +0200288 mutex_lock(&mtdblks_lock);
Ben Hutchingscbfe93e2010-01-29 20:58:37 +0000289 if (mtdblk->count) {
290 mtdblk->count++;
Matthias Kaehlcked676c112009-07-14 22:04:29 +0200291 mutex_unlock(&mtdblks_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700292 return 0;
293 }
Thomas Gleixner97894cd2005-11-07 11:15:26 +0000294
Linus Torvalds1da177e2005-04-16 15:20:36 -0700295 /* OK, it's not open. Create cache info for it */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700296 mtdblk->count = 1;
Ingo Molnar48b19262006-03-31 02:29:41 -0800297 mutex_init(&mtdblk->cache_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700298 mtdblk->cache_state = STATE_EMPTY;
Ben Hutchingscbfe93e2010-01-29 20:58:37 +0000299 if (!(mbd->mtd->flags & MTD_NO_ERASE) && mbd->mtd->erasesize) {
300 mtdblk->cache_size = mbd->mtd->erasesize;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700301 mtdblk->cache_data = NULL;
302 }
303
Matthias Kaehlcked676c112009-07-14 22:04:29 +0200304 mutex_unlock(&mtdblks_lock);
Thomas Gleixner97894cd2005-11-07 11:15:26 +0000305
Brian Norris289c0522011-07-19 10:06:09 -0700306 pr_debug("ok\n");
Linus Torvalds1da177e2005-04-16 15:20:36 -0700307
308 return 0;
309}
310
311static int mtdblock_release(struct mtd_blktrans_dev *mbd)
312{
Ben Hutchingscbfe93e2010-01-29 20:58:37 +0000313 struct mtdblk_dev *mtdblk = container_of(mbd, struct mtdblk_dev, mbd);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700314
Brian Norris289c0522011-07-19 10:06:09 -0700315 pr_debug("mtdblock_release\n");
Linus Torvalds1da177e2005-04-16 15:20:36 -0700316
Matthias Kaehlcked676c112009-07-14 22:04:29 +0200317 mutex_lock(&mtdblks_lock);
318
Ingo Molnar48b19262006-03-31 02:29:41 -0800319 mutex_lock(&mtdblk->cache_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700320 write_cached_data(mtdblk);
Ingo Molnar48b19262006-03-31 02:29:41 -0800321 mutex_unlock(&mtdblk->cache_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700322
323 if (!--mtdblk->count) {
Ben Hutchingscbfe93e2010-01-29 20:58:37 +0000324 /* It was the last usage. Free the cache */
325 if (mbd->mtd->sync)
326 mbd->mtd->sync(mbd->mtd);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700327 vfree(mtdblk->cache_data);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700328 }
Matthias Kaehlcked676c112009-07-14 22:04:29 +0200329
330 mutex_unlock(&mtdblks_lock);
331
Brian Norris289c0522011-07-19 10:06:09 -0700332 pr_debug("ok\n");
Linus Torvalds1da177e2005-04-16 15:20:36 -0700333
334 return 0;
Thomas Gleixner97894cd2005-11-07 11:15:26 +0000335}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700336
337static int mtdblock_flush(struct mtd_blktrans_dev *dev)
338{
Ben Hutchingscbfe93e2010-01-29 20:58:37 +0000339 struct mtdblk_dev *mtdblk = container_of(dev, struct mtdblk_dev, mbd);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700340
Ingo Molnar48b19262006-03-31 02:29:41 -0800341 mutex_lock(&mtdblk->cache_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700342 write_cached_data(mtdblk);
Ingo Molnar48b19262006-03-31 02:29:41 -0800343 mutex_unlock(&mtdblk->cache_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700344
Ben Hutchingscbfe93e2010-01-29 20:58:37 +0000345 if (dev->mtd->sync)
346 dev->mtd->sync(dev->mtd);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700347 return 0;
348}
349
350static void mtdblock_add_mtd(struct mtd_blktrans_ops *tr, struct mtd_info *mtd)
351{
Ben Hutchingscbfe93e2010-01-29 20:58:37 +0000352 struct mtdblk_dev *dev = kzalloc(sizeof(*dev), GFP_KERNEL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700353
354 if (!dev)
355 return;
356
Ben Hutchingscbfe93e2010-01-29 20:58:37 +0000357 dev->mbd.mtd = mtd;
358 dev->mbd.devnum = mtd->index;
Richard Purdie19187672006-10-27 09:09:33 +0100359
Ben Hutchingscbfe93e2010-01-29 20:58:37 +0000360 dev->mbd.size = mtd->size >> 9;
361 dev->mbd.tr = tr;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700362
363 if (!(mtd->flags & MTD_WRITEABLE))
Ben Hutchingscbfe93e2010-01-29 20:58:37 +0000364 dev->mbd.readonly = 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700365
Maxim Levitsky298304f2010-02-22 20:39:31 +0200366 if (add_mtd_blktrans_dev(&dev->mbd))
367 kfree(dev);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700368}
369
370static void mtdblock_remove_dev(struct mtd_blktrans_dev *dev)
371{
372 del_mtd_blktrans_dev(dev);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700373}
374
375static struct mtd_blktrans_ops mtdblock_tr = {
376 .name = "mtdblock",
377 .major = 31,
378 .part_bits = 0,
Richard Purdie19187672006-10-27 09:09:33 +0100379 .blksize = 512,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700380 .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
390static int __init init_mtdblock(void)
391{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700392 return register_mtd_blktrans(&mtdblock_tr);
393}
394
395static void __exit cleanup_mtdblock(void)
396{
397 deregister_mtd_blktrans(&mtdblock_tr);
398}
399
400module_init(init_mtdblock);
401module_exit(cleanup_mtdblock);
402
403
404MODULE_LICENSE("GPL");
Nicolas Pitre2f82af02009-09-14 03:25:28 -0400405MODULE_AUTHOR("Nicolas Pitre <nico@fluxnic.net> et al.");
Linus Torvalds1da177e2005-04-16 15:20:36 -0700406MODULE_DESCRIPTION("Caching read/erase/writeback block device emulation access to MTD devices");