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