Commit | Line | Data |
---|---|---|
97894cda | 1 | /* |
1da177e4 LT |
2 | * Direct MTD block device access |
3 | * | |
1da177e4 LT |
4 | * (C) 2000-2003 Nicolas Pitre <nico@cam.org> |
5 | * (C) 1999-2003 David Woodhouse <dwmw2@infradead.org> | |
6 | */ | |
7 | ||
1da177e4 LT |
8 | #include <linux/fs.h> |
9 | #include <linux/init.h> | |
15fdc52f TG |
10 | #include <linux/kernel.h> |
11 | #include <linux/module.h> | |
12 | #include <linux/sched.h> | |
1da177e4 | 13 | #include <linux/slab.h> |
15fdc52f | 14 | #include <linux/types.h> |
1da177e4 | 15 | #include <linux/vmalloc.h> |
15fdc52f | 16 | |
1da177e4 LT |
17 | #include <linux/mtd/mtd.h> |
18 | #include <linux/mtd/blktrans.h> | |
48b19268 IM |
19 | #include <linux/mutex.h> |
20 | ||
1da177e4 LT |
21 | |
22 | static struct mtdblk_dev { | |
23 | struct mtd_info *mtd; | |
24 | int count; | |
48b19268 | 25 | struct mutex cache_mutex; |
1da177e4 LT |
26 | unsigned char *cache_data; |
27 | unsigned long cache_offset; | |
28 | unsigned int cache_size; | |
29 | enum { STATE_EMPTY, STATE_CLEAN, STATE_DIRTY } cache_state; | |
30 | } *mtdblks[MAX_MTD_DEVICES]; | |
31 | ||
d676c117 MK |
32 | static struct mutex mtdblks_lock; |
33 | ||
1da177e4 LT |
34 | /* |
35 | * Cache stuff... | |
97894cda | 36 | * |
1da177e4 LT |
37 | * Since typical flash erasable sectors are much larger than what Linux's |
38 | * buffer cache can handle, we must implement read-modify-write on flash | |
39 | * sectors for each block write requests. To avoid over-erasing flash sectors | |
40 | * and to speed things up, we locally cache a whole flash sector while it is | |
41 | * being written to until a different sector is required. | |
42 | */ | |
43 | ||
44 | static void erase_callback(struct erase_info *done) | |
45 | { | |
46 | wait_queue_head_t *wait_q = (wait_queue_head_t *)done->priv; | |
47 | wake_up(wait_q); | |
48 | } | |
49 | ||
97894cda | 50 | static int erase_write (struct mtd_info *mtd, unsigned long pos, |
1da177e4 LT |
51 | int len, const char *buf) |
52 | { | |
53 | struct erase_info erase; | |
54 | DECLARE_WAITQUEUE(wait, current); | |
55 | wait_queue_head_t wait_q; | |
56 | size_t retlen; | |
57 | int ret; | |
58 | ||
59 | /* | |
60 | * First, let's erase the flash block. | |
61 | */ | |
62 | ||
63 | init_waitqueue_head(&wait_q); | |
64 | erase.mtd = mtd; | |
65 | erase.callback = erase_callback; | |
66 | erase.addr = pos; | |
67 | erase.len = len; | |
68 | erase.priv = (u_long)&wait_q; | |
69 | ||
70 | set_current_state(TASK_INTERRUPTIBLE); | |
71 | add_wait_queue(&wait_q, &wait); | |
72 | ||
f4a43cfc | 73 | ret = mtd->erase(mtd, &erase); |
1da177e4 LT |
74 | if (ret) { |
75 | set_current_state(TASK_RUNNING); | |
76 | remove_wait_queue(&wait_q, &wait); | |
77 | printk (KERN_WARNING "mtdblock: erase of region [0x%lx, 0x%x] " | |
78 | "on \"%s\" failed\n", | |
79 | pos, len, mtd->name); | |
80 | return ret; | |
81 | } | |
82 | ||
83 | schedule(); /* Wait for erase to finish. */ | |
84 | remove_wait_queue(&wait_q, &wait); | |
85 | ||
86 | /* | |
87 | * Next, writhe data to flash. | |
88 | */ | |
89 | ||
f4a43cfc | 90 | ret = mtd->write(mtd, pos, len, &retlen, buf); |
1da177e4 LT |
91 | if (ret) |
92 | return ret; | |
93 | if (retlen != len) | |
94 | return -EIO; | |
95 | return 0; | |
96 | } | |
97 | ||
98 | ||
99 | static int write_cached_data (struct mtdblk_dev *mtdblk) | |
100 | { | |
101 | struct mtd_info *mtd = mtdblk->mtd; | |
102 | int ret; | |
103 | ||
104 | if (mtdblk->cache_state != STATE_DIRTY) | |
105 | return 0; | |
106 | ||
107 | DEBUG(MTD_DEBUG_LEVEL2, "mtdblock: writing cached data for \"%s\" " | |
97894cda | 108 | "at 0x%lx, size 0x%x\n", mtd->name, |
1da177e4 | 109 | mtdblk->cache_offset, mtdblk->cache_size); |
97894cda TG |
110 | |
111 | ret = erase_write (mtd, mtdblk->cache_offset, | |
1da177e4 LT |
112 | mtdblk->cache_size, mtdblk->cache_data); |
113 | if (ret) | |
114 | return ret; | |
115 | ||
116 | /* | |
117 | * Here we could argubly set the cache state to STATE_CLEAN. | |
97894cda TG |
118 | * However this could lead to inconsistency since we will not |
119 | * be notified if this content is altered on the flash by other | |
1da177e4 LT |
120 | * means. Let's declare it empty and leave buffering tasks to |
121 | * the buffer cache instead. | |
122 | */ | |
123 | mtdblk->cache_state = STATE_EMPTY; | |
124 | return 0; | |
125 | } | |
126 | ||
127 | ||
97894cda | 128 | static int do_cached_write (struct mtdblk_dev *mtdblk, unsigned long pos, |
1da177e4 LT |
129 | int len, const char *buf) |
130 | { | |
131 | struct mtd_info *mtd = mtdblk->mtd; | |
132 | unsigned int sect_size = mtdblk->cache_size; | |
133 | size_t retlen; | |
134 | int ret; | |
135 | ||
136 | DEBUG(MTD_DEBUG_LEVEL2, "mtdblock: write on \"%s\" at 0x%lx, size 0x%x\n", | |
137 | mtd->name, pos, len); | |
97894cda | 138 | |
1da177e4 | 139 | if (!sect_size) |
f4a43cfc | 140 | return mtd->write(mtd, pos, len, &retlen, buf); |
1da177e4 LT |
141 | |
142 | while (len > 0) { | |
143 | unsigned long sect_start = (pos/sect_size)*sect_size; | |
144 | unsigned int offset = pos - sect_start; | |
145 | unsigned int size = sect_size - offset; | |
97894cda | 146 | if( size > len ) |
1da177e4 LT |
147 | size = len; |
148 | ||
149 | if (size == sect_size) { | |
97894cda | 150 | /* |
1da177e4 LT |
151 | * We are covering a whole sector. Thus there is no |
152 | * need to bother with the cache while it may still be | |
153 | * useful for other partial writes. | |
154 | */ | |
155 | ret = erase_write (mtd, pos, size, buf); | |
156 | if (ret) | |
157 | return ret; | |
158 | } else { | |
159 | /* Partial sector: need to use the cache */ | |
160 | ||
161 | if (mtdblk->cache_state == STATE_DIRTY && | |
162 | mtdblk->cache_offset != sect_start) { | |
163 | ret = write_cached_data(mtdblk); | |
97894cda | 164 | if (ret) |
1da177e4 LT |
165 | return ret; |
166 | } | |
167 | ||
168 | if (mtdblk->cache_state == STATE_EMPTY || | |
169 | mtdblk->cache_offset != sect_start) { | |
170 | /* fill the cache with the current sector */ | |
171 | mtdblk->cache_state = STATE_EMPTY; | |
f4a43cfc TG |
172 | ret = mtd->read(mtd, sect_start, sect_size, |
173 | &retlen, mtdblk->cache_data); | |
1da177e4 LT |
174 | if (ret) |
175 | return ret; | |
176 | if (retlen != sect_size) | |
177 | return -EIO; | |
178 | ||
179 | mtdblk->cache_offset = sect_start; | |
180 | mtdblk->cache_size = sect_size; | |
181 | mtdblk->cache_state = STATE_CLEAN; | |
182 | } | |
183 | ||
184 | /* write data to our local cache */ | |
185 | memcpy (mtdblk->cache_data + offset, buf, size); | |
186 | mtdblk->cache_state = STATE_DIRTY; | |
187 | } | |
188 | ||
189 | buf += size; | |
190 | pos += size; | |
191 | len -= size; | |
192 | } | |
193 | ||
194 | return 0; | |
195 | } | |
196 | ||
197 | ||
97894cda | 198 | static int do_cached_read (struct mtdblk_dev *mtdblk, unsigned long pos, |
1da177e4 LT |
199 | int len, char *buf) |
200 | { | |
201 | struct mtd_info *mtd = mtdblk->mtd; | |
202 | unsigned int sect_size = mtdblk->cache_size; | |
203 | size_t retlen; | |
204 | int ret; | |
205 | ||
97894cda | 206 | DEBUG(MTD_DEBUG_LEVEL2, "mtdblock: read on \"%s\" at 0x%lx, size 0x%x\n", |
1da177e4 | 207 | mtd->name, pos, len); |
97894cda | 208 | |
1da177e4 | 209 | if (!sect_size) |
f4a43cfc | 210 | return mtd->read(mtd, pos, len, &retlen, buf); |
1da177e4 LT |
211 | |
212 | while (len > 0) { | |
213 | unsigned long sect_start = (pos/sect_size)*sect_size; | |
214 | unsigned int offset = pos - sect_start; | |
215 | unsigned int size = sect_size - offset; | |
97894cda | 216 | if (size > len) |
1da177e4 LT |
217 | size = len; |
218 | ||
219 | /* | |
220 | * Check if the requested data is already cached | |
221 | * Read the requested amount of data from our internal cache if it | |
222 | * contains what we want, otherwise we read the data directly | |
223 | * from flash. | |
224 | */ | |
225 | if (mtdblk->cache_state != STATE_EMPTY && | |
226 | mtdblk->cache_offset == sect_start) { | |
227 | memcpy (buf, mtdblk->cache_data + offset, size); | |
228 | } else { | |
f4a43cfc | 229 | ret = mtd->read(mtd, pos, size, &retlen, buf); |
1da177e4 LT |
230 | if (ret) |
231 | return ret; | |
232 | if (retlen != size) | |
233 | return -EIO; | |
234 | } | |
235 | ||
236 | buf += size; | |
237 | pos += size; | |
238 | len -= size; | |
239 | } | |
240 | ||
241 | return 0; | |
242 | } | |
243 | ||
244 | static int mtdblock_readsect(struct mtd_blktrans_dev *dev, | |
245 | unsigned long block, char *buf) | |
246 | { | |
247 | struct mtdblk_dev *mtdblk = mtdblks[dev->devnum]; | |
248 | return do_cached_read(mtdblk, block<<9, 512, buf); | |
249 | } | |
250 | ||
251 | static int mtdblock_writesect(struct mtd_blktrans_dev *dev, | |
252 | unsigned long block, char *buf) | |
253 | { | |
254 | struct mtdblk_dev *mtdblk = mtdblks[dev->devnum]; | |
255 | if (unlikely(!mtdblk->cache_data && mtdblk->cache_size)) { | |
256 | mtdblk->cache_data = vmalloc(mtdblk->mtd->erasesize); | |
257 | if (!mtdblk->cache_data) | |
258 | return -EINTR; | |
259 | /* -EINTR is not really correct, but it is the best match | |
260 | * documented in man 2 write for all cases. We could also | |
261 | * return -EAGAIN sometimes, but why bother? | |
262 | */ | |
263 | } | |
264 | return do_cached_write(mtdblk, block<<9, 512, buf); | |
265 | } | |
266 | ||
267 | static int mtdblock_open(struct mtd_blktrans_dev *mbd) | |
268 | { | |
269 | struct mtdblk_dev *mtdblk; | |
270 | struct mtd_info *mtd = mbd->mtd; | |
271 | int dev = mbd->devnum; | |
272 | ||
273 | DEBUG(MTD_DEBUG_LEVEL1,"mtdblock_open\n"); | |
97894cda | 274 | |
d676c117 | 275 | mutex_lock(&mtdblks_lock); |
1da177e4 LT |
276 | if (mtdblks[dev]) { |
277 | mtdblks[dev]->count++; | |
d676c117 | 278 | mutex_unlock(&mtdblks_lock); |
1da177e4 LT |
279 | return 0; |
280 | } | |
97894cda | 281 | |
1da177e4 | 282 | /* OK, it's not open. Create cache info for it */ |
95b93a0c | 283 | mtdblk = kzalloc(sizeof(struct mtdblk_dev), GFP_KERNEL); |
d676c117 MK |
284 | if (!mtdblk) { |
285 | mutex_unlock(&mtdblks_lock); | |
1da177e4 | 286 | return -ENOMEM; |
d676c117 | 287 | } |
1da177e4 | 288 | |
1da177e4 LT |
289 | mtdblk->count = 1; |
290 | mtdblk->mtd = mtd; | |
291 | ||
48b19268 | 292 | mutex_init(&mtdblk->cache_mutex); |
1da177e4 | 293 | mtdblk->cache_state = STATE_EMPTY; |
92cbfdcc | 294 | if ( !(mtdblk->mtd->flags & MTD_NO_ERASE) && mtdblk->mtd->erasesize) { |
1da177e4 LT |
295 | mtdblk->cache_size = mtdblk->mtd->erasesize; |
296 | mtdblk->cache_data = NULL; | |
297 | } | |
298 | ||
299 | mtdblks[dev] = mtdblk; | |
d676c117 | 300 | mutex_unlock(&mtdblks_lock); |
97894cda | 301 | |
1da177e4 LT |
302 | DEBUG(MTD_DEBUG_LEVEL1, "ok\n"); |
303 | ||
304 | return 0; | |
305 | } | |
306 | ||
307 | static int mtdblock_release(struct mtd_blktrans_dev *mbd) | |
308 | { | |
309 | int dev = mbd->devnum; | |
310 | struct mtdblk_dev *mtdblk = mtdblks[dev]; | |
311 | ||
312 | DEBUG(MTD_DEBUG_LEVEL1, "mtdblock_release\n"); | |
313 | ||
d676c117 MK |
314 | mutex_lock(&mtdblks_lock); |
315 | ||
48b19268 | 316 | mutex_lock(&mtdblk->cache_mutex); |
1da177e4 | 317 | write_cached_data(mtdblk); |
48b19268 | 318 | mutex_unlock(&mtdblk->cache_mutex); |
1da177e4 LT |
319 | |
320 | if (!--mtdblk->count) { | |
321 | /* It was the last usage. Free the device */ | |
322 | mtdblks[dev] = NULL; | |
323 | if (mtdblk->mtd->sync) | |
324 | mtdblk->mtd->sync(mtdblk->mtd); | |
325 | vfree(mtdblk->cache_data); | |
326 | kfree(mtdblk); | |
327 | } | |
d676c117 MK |
328 | |
329 | mutex_unlock(&mtdblks_lock); | |
330 | ||
1da177e4 LT |
331 | DEBUG(MTD_DEBUG_LEVEL1, "ok\n"); |
332 | ||
333 | return 0; | |
97894cda | 334 | } |
1da177e4 LT |
335 | |
336 | static int mtdblock_flush(struct mtd_blktrans_dev *dev) | |
337 | { | |
338 | struct mtdblk_dev *mtdblk = mtdblks[dev->devnum]; | |
339 | ||
48b19268 | 340 | mutex_lock(&mtdblk->cache_mutex); |
1da177e4 | 341 | write_cached_data(mtdblk); |
48b19268 | 342 | mutex_unlock(&mtdblk->cache_mutex); |
1da177e4 LT |
343 | |
344 | if (mtdblk->mtd->sync) | |
345 | mtdblk->mtd->sync(mtdblk->mtd); | |
346 | return 0; | |
347 | } | |
348 | ||
349 | static void mtdblock_add_mtd(struct mtd_blktrans_ops *tr, struct mtd_info *mtd) | |
350 | { | |
95b93a0c | 351 | struct mtd_blktrans_dev *dev = kzalloc(sizeof(*dev), GFP_KERNEL); |
1da177e4 LT |
352 | |
353 | if (!dev) | |
354 | return; | |
355 | ||
1da177e4 LT |
356 | dev->mtd = mtd; |
357 | dev->devnum = mtd->index; | |
19187672 | 358 | |
1da177e4 LT |
359 | dev->size = mtd->size >> 9; |
360 | dev->tr = tr; | |
361 | ||
362 | if (!(mtd->flags & MTD_WRITEABLE)) | |
363 | dev->readonly = 1; | |
364 | ||
365 | add_mtd_blktrans_dev(dev); | |
366 | } | |
367 | ||
368 | static void mtdblock_remove_dev(struct mtd_blktrans_dev *dev) | |
369 | { | |
370 | del_mtd_blktrans_dev(dev); | |
371 | kfree(dev); | |
372 | } | |
373 | ||
374 | static struct mtd_blktrans_ops mtdblock_tr = { | |
375 | .name = "mtdblock", | |
376 | .major = 31, | |
377 | .part_bits = 0, | |
19187672 | 378 | .blksize = 512, |
1da177e4 LT |
379 | .open = mtdblock_open, |
380 | .flush = mtdblock_flush, | |
381 | .release = mtdblock_release, | |
382 | .readsect = mtdblock_readsect, | |
383 | .writesect = mtdblock_writesect, | |
384 | .add_mtd = mtdblock_add_mtd, | |
385 | .remove_dev = mtdblock_remove_dev, | |
386 | .owner = THIS_MODULE, | |
387 | }; | |
388 | ||
389 | static int __init init_mtdblock(void) | |
390 | { | |
d676c117 MK |
391 | mutex_init(&mtdblks_lock); |
392 | ||
1da177e4 LT |
393 | return register_mtd_blktrans(&mtdblock_tr); |
394 | } | |
395 | ||
396 | static void __exit cleanup_mtdblock(void) | |
397 | { | |
398 | deregister_mtd_blktrans(&mtdblock_tr); | |
399 | } | |
400 | ||
401 | module_init(init_mtdblock); | |
402 | module_exit(cleanup_mtdblock); | |
403 | ||
404 | ||
405 | MODULE_LICENSE("GPL"); | |
406 | MODULE_AUTHOR("Nicolas Pitre <nico@cam.org> et al."); | |
407 | MODULE_DESCRIPTION("Caching read/erase/writeback block device emulation access to MTD devices"); |