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Commit | Line | Data |
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97894cda | 1 | /* |
1da177e4 LT |
2 | * Direct MTD block device access |
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 | */ |
22 | ||
1da177e4 LT |
23 | #include <linux/fs.h> |
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> |
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 { |
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 | /* |
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 | */ |
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 | |
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 |
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) |
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, |
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) |
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) { |
291 | mtdblk->count++; | |
d676c117 | 292 | mutex_unlock(&mtdblks_lock); |
1da177e4 LT |
293 | return 0; |
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) { |
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); |
319 | ||
48b19268 | 320 | mutex_lock(&mtdblk->cache_mutex); |
1da177e4 | 321 | write_cached_data(mtdblk); |
48b19268 | 322 | mutex_unlock(&mtdblk->cache_mutex); |
1da177e4 LT |
323 | |
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; |
358 | dev->mbd.devnum = mtd->index; | |
19187672 | 359 | |
cbfe93e9 BH |
360 | dev->mbd.size = mtd->size >> 9; |
361 | dev->mbd.tr = tr; | |
1da177e4 LT |
362 | |
363 | if (!(mtd->flags & MTD_WRITEABLE)) | |
cbfe93e9 | 364 | dev->mbd.readonly = 1; |
1da177e4 | 365 | |
298304f1 ML |
366 | if (add_mtd_blktrans_dev(&dev->mbd)) |
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"); |