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Commit | Line | Data |
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97894cda | 1 | /* |
1da177e4 LT |
2 | * Direct MTD block device access |
3 | * | |
97894cda | 4 | * $Id: mtdblock.c,v 1.68 2005/11/07 11:14:20 gleixner Exp $ |
1da177e4 LT |
5 | * |
6 | * (C) 2000-2003 Nicolas Pitre <nico@cam.org> | |
7 | * (C) 1999-2003 David Woodhouse <dwmw2@infradead.org> | |
8 | */ | |
9 | ||
10 | #include <linux/config.h> | |
1da177e4 LT |
11 | #include <linux/fs.h> |
12 | #include <linux/init.h> | |
15fdc52f TG |
13 | #include <linux/kernel.h> |
14 | #include <linux/module.h> | |
15 | #include <linux/sched.h> | |
1da177e4 | 16 | #include <linux/slab.h> |
15fdc52f | 17 | #include <linux/types.h> |
1da177e4 | 18 | #include <linux/vmalloc.h> |
15fdc52f | 19 | |
1da177e4 LT |
20 | #include <linux/mtd/mtd.h> |
21 | #include <linux/mtd/blktrans.h> | |
48b19268 IM |
22 | #include <linux/mutex.h> |
23 | ||
1da177e4 LT |
24 | |
25 | static struct mtdblk_dev { | |
26 | struct mtd_info *mtd; | |
27 | int count; | |
48b19268 | 28 | struct mutex cache_mutex; |
1da177e4 LT |
29 | unsigned char *cache_data; |
30 | unsigned long cache_offset; | |
31 | unsigned int cache_size; | |
32 | enum { STATE_EMPTY, STATE_CLEAN, STATE_DIRTY } cache_state; | |
33 | } *mtdblks[MAX_MTD_DEVICES]; | |
34 | ||
35 | /* | |
36 | * Cache stuff... | |
97894cda | 37 | * |
1da177e4 LT |
38 | * Since typical flash erasable sectors are much larger than what Linux's |
39 | * buffer cache can handle, we must implement read-modify-write on flash | |
40 | * sectors for each block write requests. To avoid over-erasing flash sectors | |
41 | * and to speed things up, we locally cache a whole flash sector while it is | |
42 | * being written to until a different sector is required. | |
43 | */ | |
44 | ||
45 | static void erase_callback(struct erase_info *done) | |
46 | { | |
47 | wait_queue_head_t *wait_q = (wait_queue_head_t *)done->priv; | |
48 | wake_up(wait_q); | |
49 | } | |
50 | ||
97894cda | 51 | static int erase_write (struct mtd_info *mtd, unsigned long pos, |
1da177e4 LT |
52 | int len, const char *buf) |
53 | { | |
54 | struct erase_info erase; | |
55 | DECLARE_WAITQUEUE(wait, current); | |
56 | wait_queue_head_t wait_q; | |
57 | size_t retlen; | |
58 | int ret; | |
59 | ||
60 | /* | |
61 | * First, let's erase the flash block. | |
62 | */ | |
63 | ||
64 | init_waitqueue_head(&wait_q); | |
65 | erase.mtd = mtd; | |
66 | erase.callback = erase_callback; | |
67 | erase.addr = pos; | |
68 | erase.len = len; | |
69 | erase.priv = (u_long)&wait_q; | |
70 | ||
71 | set_current_state(TASK_INTERRUPTIBLE); | |
72 | add_wait_queue(&wait_q, &wait); | |
73 | ||
74 | ret = MTD_ERASE(mtd, &erase); | |
75 | if (ret) { | |
76 | set_current_state(TASK_RUNNING); | |
77 | remove_wait_queue(&wait_q, &wait); | |
78 | printk (KERN_WARNING "mtdblock: erase of region [0x%lx, 0x%x] " | |
79 | "on \"%s\" failed\n", | |
80 | pos, len, mtd->name); | |
81 | return ret; | |
82 | } | |
83 | ||
84 | schedule(); /* Wait for erase to finish. */ | |
85 | remove_wait_queue(&wait_q, &wait); | |
86 | ||
87 | /* | |
88 | * Next, writhe data to flash. | |
89 | */ | |
90 | ||
91 | ret = MTD_WRITE (mtd, pos, len, &retlen, buf); | |
92 | if (ret) | |
93 | return ret; | |
94 | if (retlen != len) | |
95 | return -EIO; | |
96 | return 0; | |
97 | } | |
98 | ||
99 | ||
100 | static int write_cached_data (struct mtdblk_dev *mtdblk) | |
101 | { | |
102 | struct mtd_info *mtd = mtdblk->mtd; | |
103 | int ret; | |
104 | ||
105 | if (mtdblk->cache_state != STATE_DIRTY) | |
106 | return 0; | |
107 | ||
108 | DEBUG(MTD_DEBUG_LEVEL2, "mtdblock: writing cached data for \"%s\" " | |
97894cda | 109 | "at 0x%lx, size 0x%x\n", mtd->name, |
1da177e4 | 110 | mtdblk->cache_offset, mtdblk->cache_size); |
97894cda TG |
111 | |
112 | ret = erase_write (mtd, mtdblk->cache_offset, | |
1da177e4 LT |
113 | mtdblk->cache_size, mtdblk->cache_data); |
114 | if (ret) | |
115 | return ret; | |
116 | ||
117 | /* | |
118 | * Here we could argubly set the cache state to STATE_CLEAN. | |
97894cda TG |
119 | * However this could lead to inconsistency since we will not |
120 | * be notified if this content is altered on the flash by other | |
1da177e4 LT |
121 | * means. Let's declare it empty and leave buffering tasks to |
122 | * the buffer cache instead. | |
123 | */ | |
124 | mtdblk->cache_state = STATE_EMPTY; | |
125 | return 0; | |
126 | } | |
127 | ||
128 | ||
97894cda | 129 | static int do_cached_write (struct mtdblk_dev *mtdblk, unsigned long pos, |
1da177e4 LT |
130 | int len, const char *buf) |
131 | { | |
132 | struct mtd_info *mtd = mtdblk->mtd; | |
133 | unsigned int sect_size = mtdblk->cache_size; | |
134 | size_t retlen; | |
135 | int ret; | |
136 | ||
137 | DEBUG(MTD_DEBUG_LEVEL2, "mtdblock: write on \"%s\" at 0x%lx, size 0x%x\n", | |
138 | mtd->name, pos, len); | |
97894cda | 139 | |
1da177e4 LT |
140 | if (!sect_size) |
141 | return MTD_WRITE (mtd, pos, len, &retlen, buf); | |
142 | ||
143 | while (len > 0) { | |
144 | unsigned long sect_start = (pos/sect_size)*sect_size; | |
145 | unsigned int offset = pos - sect_start; | |
146 | unsigned int size = sect_size - offset; | |
97894cda | 147 | if( size > len ) |
1da177e4 LT |
148 | size = len; |
149 | ||
150 | if (size == sect_size) { | |
97894cda | 151 | /* |
1da177e4 LT |
152 | * We are covering a whole sector. Thus there is no |
153 | * need to bother with the cache while it may still be | |
154 | * useful for other partial writes. | |
155 | */ | |
156 | ret = erase_write (mtd, pos, size, buf); | |
157 | if (ret) | |
158 | return ret; | |
159 | } else { | |
160 | /* Partial sector: need to use the cache */ | |
161 | ||
162 | if (mtdblk->cache_state == STATE_DIRTY && | |
163 | mtdblk->cache_offset != sect_start) { | |
164 | ret = write_cached_data(mtdblk); | |
97894cda | 165 | if (ret) |
1da177e4 LT |
166 | return ret; |
167 | } | |
168 | ||
169 | if (mtdblk->cache_state == STATE_EMPTY || | |
170 | mtdblk->cache_offset != sect_start) { | |
171 | /* fill the cache with the current sector */ | |
172 | mtdblk->cache_state = STATE_EMPTY; | |
173 | ret = MTD_READ(mtd, sect_start, sect_size, &retlen, mtdblk->cache_data); | |
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 LT |
209 | if (!sect_size) |
210 | return MTD_READ (mtd, pos, len, &retlen, buf); | |
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 { | |
229 | ret = MTD_READ (mtd, pos, size, &retlen, buf); | |
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 | |
1da177e4 LT |
275 | if (mtdblks[dev]) { |
276 | mtdblks[dev]->count++; | |
277 | return 0; | |
278 | } | |
97894cda | 279 | |
1da177e4 LT |
280 | /* OK, it's not open. Create cache info for it */ |
281 | mtdblk = kmalloc(sizeof(struct mtdblk_dev), GFP_KERNEL); | |
282 | if (!mtdblk) | |
283 | return -ENOMEM; | |
284 | ||
285 | memset(mtdblk, 0, sizeof(*mtdblk)); | |
286 | mtdblk->count = 1; | |
287 | mtdblk->mtd = mtd; | |
288 | ||
48b19268 | 289 | mutex_init(&mtdblk->cache_mutex); |
1da177e4 | 290 | mtdblk->cache_state = STATE_EMPTY; |
7f7c08df | 291 | if (mtdblk->mtd->type != MTD_RAM && mtdblk->mtd->erasesize) { |
1da177e4 LT |
292 | mtdblk->cache_size = mtdblk->mtd->erasesize; |
293 | mtdblk->cache_data = NULL; | |
294 | } | |
295 | ||
296 | mtdblks[dev] = mtdblk; | |
97894cda | 297 | |
1da177e4 LT |
298 | DEBUG(MTD_DEBUG_LEVEL1, "ok\n"); |
299 | ||
300 | return 0; | |
301 | } | |
302 | ||
303 | static int mtdblock_release(struct mtd_blktrans_dev *mbd) | |
304 | { | |
305 | int dev = mbd->devnum; | |
306 | struct mtdblk_dev *mtdblk = mtdblks[dev]; | |
307 | ||
308 | DEBUG(MTD_DEBUG_LEVEL1, "mtdblock_release\n"); | |
309 | ||
48b19268 | 310 | mutex_lock(&mtdblk->cache_mutex); |
1da177e4 | 311 | write_cached_data(mtdblk); |
48b19268 | 312 | mutex_unlock(&mtdblk->cache_mutex); |
1da177e4 LT |
313 | |
314 | if (!--mtdblk->count) { | |
315 | /* It was the last usage. Free the device */ | |
316 | mtdblks[dev] = NULL; | |
317 | if (mtdblk->mtd->sync) | |
318 | mtdblk->mtd->sync(mtdblk->mtd); | |
319 | vfree(mtdblk->cache_data); | |
320 | kfree(mtdblk); | |
321 | } | |
322 | DEBUG(MTD_DEBUG_LEVEL1, "ok\n"); | |
323 | ||
324 | return 0; | |
97894cda | 325 | } |
1da177e4 LT |
326 | |
327 | static int mtdblock_flush(struct mtd_blktrans_dev *dev) | |
328 | { | |
329 | struct mtdblk_dev *mtdblk = mtdblks[dev->devnum]; | |
330 | ||
48b19268 | 331 | mutex_lock(&mtdblk->cache_mutex); |
1da177e4 | 332 | write_cached_data(mtdblk); |
48b19268 | 333 | mutex_unlock(&mtdblk->cache_mutex); |
1da177e4 LT |
334 | |
335 | if (mtdblk->mtd->sync) | |
336 | mtdblk->mtd->sync(mtdblk->mtd); | |
337 | return 0; | |
338 | } | |
339 | ||
340 | static void mtdblock_add_mtd(struct mtd_blktrans_ops *tr, struct mtd_info *mtd) | |
341 | { | |
342 | struct mtd_blktrans_dev *dev = kmalloc(sizeof(*dev), GFP_KERNEL); | |
343 | ||
344 | if (!dev) | |
345 | return; | |
346 | ||
347 | memset(dev, 0, sizeof(*dev)); | |
348 | ||
349 | dev->mtd = mtd; | |
350 | dev->devnum = mtd->index; | |
351 | dev->blksize = 512; | |
352 | dev->size = mtd->size >> 9; | |
353 | dev->tr = tr; | |
354 | ||
355 | if (!(mtd->flags & MTD_WRITEABLE)) | |
356 | dev->readonly = 1; | |
357 | ||
358 | add_mtd_blktrans_dev(dev); | |
359 | } | |
360 | ||
361 | static void mtdblock_remove_dev(struct mtd_blktrans_dev *dev) | |
362 | { | |
363 | del_mtd_blktrans_dev(dev); | |
364 | kfree(dev); | |
365 | } | |
366 | ||
367 | static struct mtd_blktrans_ops mtdblock_tr = { | |
368 | .name = "mtdblock", | |
369 | .major = 31, | |
370 | .part_bits = 0, | |
371 | .open = mtdblock_open, | |
372 | .flush = mtdblock_flush, | |
373 | .release = mtdblock_release, | |
374 | .readsect = mtdblock_readsect, | |
375 | .writesect = mtdblock_writesect, | |
376 | .add_mtd = mtdblock_add_mtd, | |
377 | .remove_dev = mtdblock_remove_dev, | |
378 | .owner = THIS_MODULE, | |
379 | }; | |
380 | ||
381 | static int __init init_mtdblock(void) | |
382 | { | |
383 | return register_mtd_blktrans(&mtdblock_tr); | |
384 | } | |
385 | ||
386 | static void __exit cleanup_mtdblock(void) | |
387 | { | |
388 | deregister_mtd_blktrans(&mtdblock_tr); | |
389 | } | |
390 | ||
391 | module_init(init_mtdblock); | |
392 | module_exit(cleanup_mtdblock); | |
393 | ||
394 | ||
395 | MODULE_LICENSE("GPL"); | |
396 | MODULE_AUTHOR("Nicolas Pitre <nico@cam.org> et al."); | |
397 | MODULE_DESCRIPTION("Caching read/erase/writeback block device emulation access to MTD devices"); |