Commit | Line | Data |
---|---|---|
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 IM |
34 | #include <linux/mutex.h> |
35 | ||
1da177e4 | 36 | |
cbfe93e9 BH |
37 | struct mtdblk_dev { |
38 | struct mtd_blktrans_dev mbd; | |
1da177e4 | 39 | int count; |
48b19268 | 40 | struct mutex cache_mutex; |
1da177e4 LT |
41 | unsigned char *cache_data; |
42 | unsigned long cache_offset; | |
43 | unsigned int cache_size; | |
44 | enum { STATE_EMPTY, STATE_CLEAN, STATE_DIRTY } cache_state; | |
cbfe93e9 | 45 | }; |
1da177e4 | 46 | |
d676c117 MK |
47 | static struct mutex mtdblks_lock; |
48 | ||
1da177e4 LT |
49 | /* |
50 | * Cache stuff... | |
97894cda | 51 | * |
1da177e4 LT |
52 | * 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 | ||
59 | static 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 | ||
97894cda | 65 | static int erase_write (struct mtd_info *mtd, unsigned long pos, |
1da177e4 LT |
66 | 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 | ||
f4a43cfc | 88 | ret = mtd->erase(mtd, &erase); |
1da177e4 LT |
89 | 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 | /* | |
dff15509 | 102 | * Next, write the data to flash. |
1da177e4 LT |
103 | */ |
104 | ||
f4a43cfc | 105 | ret = mtd->write(mtd, pos, len, &retlen, buf); |
1da177e4 LT |
106 | if (ret) |
107 | return ret; | |
108 | if (retlen != len) | |
109 | return -EIO; | |
110 | return 0; | |
111 | } | |
112 | ||
113 | ||
114 | static int write_cached_data (struct mtdblk_dev *mtdblk) | |
115 | { | |
cbfe93e9 | 116 | struct mtd_info *mtd = mtdblk->mbd.mtd; |
1da177e4 LT |
117 | int ret; |
118 | ||
119 | if (mtdblk->cache_state != STATE_DIRTY) | |
120 | return 0; | |
121 | ||
122 | DEBUG(MTD_DEBUG_LEVEL2, "mtdblock: writing cached data for \"%s\" " | |
97894cda | 123 | "at 0x%lx, size 0x%x\n", mtd->name, |
1da177e4 | 124 | mtdblk->cache_offset, mtdblk->cache_size); |
97894cda TG |
125 | |
126 | ret = erase_write (mtd, mtdblk->cache_offset, | |
1da177e4 LT |
127 | mtdblk->cache_size, mtdblk->cache_data); |
128 | if (ret) | |
129 | return ret; | |
130 | ||
131 | /* | |
25985edc | 132 | * Here we could arguably set the cache state to STATE_CLEAN. |
97894cda TG |
133 | * However this could lead to inconsistency since we will not |
134 | * be notified if this content is altered on the flash by other | |
1da177e4 LT |
135 | * 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 | ||
97894cda | 143 | static int do_cached_write (struct mtdblk_dev *mtdblk, unsigned long pos, |
1da177e4 LT |
144 | int len, const char *buf) |
145 | { | |
cbfe93e9 | 146 | struct mtd_info *mtd = mtdblk->mbd.mtd; |
1da177e4 LT |
147 | unsigned int sect_size = mtdblk->cache_size; |
148 | size_t retlen; | |
149 | int ret; | |
150 | ||
151 | DEBUG(MTD_DEBUG_LEVEL2, "mtdblock: write on \"%s\" at 0x%lx, size 0x%x\n", | |
152 | mtd->name, pos, len); | |
97894cda | 153 | |
1da177e4 | 154 | if (!sect_size) |
f4a43cfc | 155 | return mtd->write(mtd, pos, len, &retlen, buf); |
1da177e4 LT |
156 | |
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; | |
97894cda | 161 | if( size > len ) |
1da177e4 LT |
162 | size = len; |
163 | ||
164 | if (size == sect_size) { | |
97894cda | 165 | /* |
1da177e4 LT |
166 | * 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); | |
97894cda | 179 | if (ret) |
1da177e4 LT |
180 | 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; | |
f4a43cfc TG |
187 | ret = mtd->read(mtd, sect_start, sect_size, |
188 | &retlen, mtdblk->cache_data); | |
1da177e4 LT |
189 | 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 | ||
97894cda | 213 | static int do_cached_read (struct mtdblk_dev *mtdblk, unsigned long pos, |
1da177e4 LT |
214 | int len, char *buf) |
215 | { | |
cbfe93e9 | 216 | struct mtd_info *mtd = mtdblk->mbd.mtd; |
1da177e4 LT |
217 | unsigned int sect_size = mtdblk->cache_size; |
218 | size_t retlen; | |
219 | int ret; | |
220 | ||
97894cda | 221 | DEBUG(MTD_DEBUG_LEVEL2, "mtdblock: read on \"%s\" at 0x%lx, size 0x%x\n", |
1da177e4 | 222 | mtd->name, pos, len); |
97894cda | 223 | |
1da177e4 | 224 | if (!sect_size) |
f4a43cfc | 225 | return mtd->read(mtd, pos, len, &retlen, buf); |
1da177e4 LT |
226 | |
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; | |
97894cda | 231 | if (size > len) |
1da177e4 LT |
232 | 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 { | |
f4a43cfc | 244 | ret = mtd->read(mtd, pos, size, &retlen, buf); |
1da177e4 LT |
245 | 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 | ||
259 | static int mtdblock_readsect(struct mtd_blktrans_dev *dev, | |
260 | unsigned long block, char *buf) | |
261 | { | |
cbfe93e9 | 262 | struct mtdblk_dev *mtdblk = container_of(dev, struct mtdblk_dev, mbd); |
1da177e4 LT |
263 | return do_cached_read(mtdblk, block<<9, 512, buf); |
264 | } | |
265 | ||
266 | static int mtdblock_writesect(struct mtd_blktrans_dev *dev, | |
267 | unsigned long block, char *buf) | |
268 | { | |
cbfe93e9 | 269 | struct mtdblk_dev *mtdblk = container_of(dev, struct mtdblk_dev, mbd); |
1da177e4 | 270 | if (unlikely(!mtdblk->cache_data && mtdblk->cache_size)) { |
cbfe93e9 | 271 | mtdblk->cache_data = vmalloc(mtdblk->mbd.mtd->erasesize); |
1da177e4 LT |
272 | 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 | ||
282 | static int mtdblock_open(struct mtd_blktrans_dev *mbd) | |
283 | { | |
cbfe93e9 | 284 | struct mtdblk_dev *mtdblk = container_of(mbd, struct mtdblk_dev, mbd); |
1da177e4 LT |
285 | |
286 | DEBUG(MTD_DEBUG_LEVEL1,"mtdblock_open\n"); | |
97894cda | 287 | |
d676c117 | 288 | mutex_lock(&mtdblks_lock); |
cbfe93e9 BH |
289 | if (mtdblk->count) { |
290 | mtdblk->count++; | |
d676c117 | 291 | mutex_unlock(&mtdblks_lock); |
1da177e4 LT |
292 | return 0; |
293 | } | |
97894cda | 294 | |
1da177e4 | 295 | /* OK, it's not open. Create cache info for it */ |
1da177e4 | 296 | mtdblk->count = 1; |
48b19268 | 297 | mutex_init(&mtdblk->cache_mutex); |
1da177e4 | 298 | mtdblk->cache_state = STATE_EMPTY; |
cbfe93e9 BH |
299 | if (!(mbd->mtd->flags & MTD_NO_ERASE) && mbd->mtd->erasesize) { |
300 | mtdblk->cache_size = mbd->mtd->erasesize; | |
1da177e4 LT |
301 | mtdblk->cache_data = NULL; |
302 | } | |
303 | ||
d676c117 | 304 | mutex_unlock(&mtdblks_lock); |
97894cda | 305 | |
1da177e4 LT |
306 | DEBUG(MTD_DEBUG_LEVEL1, "ok\n"); |
307 | ||
308 | return 0; | |
309 | } | |
310 | ||
311 | static int mtdblock_release(struct mtd_blktrans_dev *mbd) | |
312 | { | |
cbfe93e9 | 313 | struct mtdblk_dev *mtdblk = container_of(mbd, struct mtdblk_dev, mbd); |
1da177e4 LT |
314 | |
315 | DEBUG(MTD_DEBUG_LEVEL1, "mtdblock_release\n"); | |
316 | ||
d676c117 MK |
317 | mutex_lock(&mtdblks_lock); |
318 | ||
48b19268 | 319 | mutex_lock(&mtdblk->cache_mutex); |
1da177e4 | 320 | write_cached_data(mtdblk); |
48b19268 | 321 | mutex_unlock(&mtdblk->cache_mutex); |
1da177e4 LT |
322 | |
323 | if (!--mtdblk->count) { | |
cbfe93e9 BH |
324 | /* It was the last usage. Free the cache */ |
325 | if (mbd->mtd->sync) | |
326 | mbd->mtd->sync(mbd->mtd); | |
1da177e4 | 327 | vfree(mtdblk->cache_data); |
1da177e4 | 328 | } |
d676c117 MK |
329 | |
330 | mutex_unlock(&mtdblks_lock); | |
331 | ||
1da177e4 LT |
332 | DEBUG(MTD_DEBUG_LEVEL1, "ok\n"); |
333 | ||
334 | return 0; | |
97894cda | 335 | } |
1da177e4 LT |
336 | |
337 | static int mtdblock_flush(struct mtd_blktrans_dev *dev) | |
338 | { | |
cbfe93e9 | 339 | struct mtdblk_dev *mtdblk = container_of(dev, struct mtdblk_dev, mbd); |
1da177e4 | 340 | |
48b19268 | 341 | mutex_lock(&mtdblk->cache_mutex); |
1da177e4 | 342 | write_cached_data(mtdblk); |
48b19268 | 343 | mutex_unlock(&mtdblk->cache_mutex); |
1da177e4 | 344 | |
cbfe93e9 BH |
345 | if (dev->mtd->sync) |
346 | dev->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", | |
377 | .major = 31, | |
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 | { | |
d676c117 MK |
392 | mutex_init(&mtdblks_lock); |
393 | ||
1da177e4 LT |
394 | return register_mtd_blktrans(&mtdblock_tr); |
395 | } | |
396 | ||
397 | static void __exit cleanup_mtdblock(void) | |
398 | { | |
399 | deregister_mtd_blktrans(&mtdblock_tr); | |
400 | } | |
401 | ||
402 | module_init(init_mtdblock); | |
403 | module_exit(cleanup_mtdblock); | |
404 | ||
405 | ||
406 | MODULE_LICENSE("GPL"); | |
2f82af08 | 407 | MODULE_AUTHOR("Nicolas Pitre <nico@fluxnic.net> et al."); |
1da177e4 | 408 | MODULE_DESCRIPTION("Caching read/erase/writeback block device emulation access to MTD devices"); |