Merge tag 'drm-intel-fixes-2013-12-11' of git://people.freedesktop.org/~danvet/drm...
[firefly-linux-kernel-4.4.55.git] / drivers / mtd / mtdblock.c
1 /*
2  * Direct MTD block device access
3  *
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  *
21  */
22
23 #include <linux/fs.h>
24 #include <linux/init.h>
25 #include <linux/kernel.h>
26 #include <linux/module.h>
27 #include <linux/sched.h>
28 #include <linux/slab.h>
29 #include <linux/types.h>
30 #include <linux/vmalloc.h>
31
32 #include <linux/mtd/mtd.h>
33 #include <linux/mtd/blktrans.h>
34 #include <linux/mutex.h>
35 #include <linux/major.h>
36
37
38 struct mtdblk_dev {
39         struct mtd_blktrans_dev mbd;
40         int count;
41         struct mutex cache_mutex;
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;
46 };
47
48 static DEFINE_MUTEX(mtdblks_lock);
49
50 /*
51  * Cache stuff...
52  *
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
66 static int erase_write (struct mtd_info *mtd, unsigned long pos,
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
89         ret = mtd_erase(mtd, &erase);
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         /*
103          * Next, write the data to flash.
104          */
105
106         ret = mtd_write(mtd, pos, len, &retlen, buf);
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 {
117         struct mtd_info *mtd = mtdblk->mbd.mtd;
118         int ret;
119
120         if (mtdblk->cache_state != STATE_DIRTY)
121                 return 0;
122
123         pr_debug("mtdblock: writing cached data for \"%s\" "
124                         "at 0x%lx, size 0x%x\n", mtd->name,
125                         mtdblk->cache_offset, mtdblk->cache_size);
126
127         ret = erase_write (mtd, mtdblk->cache_offset,
128                            mtdblk->cache_size, mtdblk->cache_data);
129         if (ret)
130                 return ret;
131
132         /*
133          * Here we could arguably set the cache state to STATE_CLEAN.
134          * However this could lead to inconsistency since we will not
135          * be notified if this content is altered on the flash by other
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
144 static int do_cached_write (struct mtdblk_dev *mtdblk, unsigned long pos,
145                             int len, const char *buf)
146 {
147         struct mtd_info *mtd = mtdblk->mbd.mtd;
148         unsigned int sect_size = mtdblk->cache_size;
149         size_t retlen;
150         int ret;
151
152         pr_debug("mtdblock: write on \"%s\" at 0x%lx, size 0x%x\n",
153                 mtd->name, pos, len);
154
155         if (!sect_size)
156                 return mtd_write(mtd, pos, len, &retlen, buf);
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;
162                 if( size > len )
163                         size = len;
164
165                 if (size == sect_size) {
166                         /*
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);
180                                 if (ret)
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;
188                                 ret = mtd_read(mtd, sect_start, sect_size,
189                                                &retlen, mtdblk->cache_data);
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
214 static int do_cached_read (struct mtdblk_dev *mtdblk, unsigned long pos,
215                            int len, char *buf)
216 {
217         struct mtd_info *mtd = mtdblk->mbd.mtd;
218         unsigned int sect_size = mtdblk->cache_size;
219         size_t retlen;
220         int ret;
221
222         pr_debug("mtdblock: read on \"%s\" at 0x%lx, size 0x%x\n",
223                         mtd->name, pos, len);
224
225         if (!sect_size)
226                 return mtd_read(mtd, pos, len, &retlen, buf);
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;
232                 if (size > len)
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 {
245                         ret = mtd_read(mtd, pos, size, &retlen, buf);
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 {
263         struct mtdblk_dev *mtdblk = container_of(dev, struct mtdblk_dev, mbd);
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 {
270         struct mtdblk_dev *mtdblk = container_of(dev, struct mtdblk_dev, mbd);
271         if (unlikely(!mtdblk->cache_data && mtdblk->cache_size)) {
272                 mtdblk->cache_data = vmalloc(mtdblk->mbd.mtd->erasesize);
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 {
285         struct mtdblk_dev *mtdblk = container_of(mbd, struct mtdblk_dev, mbd);
286
287         pr_debug("mtdblock_open\n");
288
289         mutex_lock(&mtdblks_lock);
290         if (mtdblk->count) {
291                 mtdblk->count++;
292                 mutex_unlock(&mtdblks_lock);
293                 return 0;
294         }
295
296         /* OK, it's not open. Create cache info for it */
297         mtdblk->count = 1;
298         mutex_init(&mtdblk->cache_mutex);
299         mtdblk->cache_state = STATE_EMPTY;
300         if (!(mbd->mtd->flags & MTD_NO_ERASE) && mbd->mtd->erasesize) {
301                 mtdblk->cache_size = mbd->mtd->erasesize;
302                 mtdblk->cache_data = NULL;
303         }
304
305         mutex_unlock(&mtdblks_lock);
306
307         pr_debug("ok\n");
308
309         return 0;
310 }
311
312 static void mtdblock_release(struct mtd_blktrans_dev *mbd)
313 {
314         struct mtdblk_dev *mtdblk = container_of(mbd, struct mtdblk_dev, mbd);
315
316         pr_debug("mtdblock_release\n");
317
318         mutex_lock(&mtdblks_lock);
319
320         mutex_lock(&mtdblk->cache_mutex);
321         write_cached_data(mtdblk);
322         mutex_unlock(&mtdblk->cache_mutex);
323
324         if (!--mtdblk->count) {
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);
331                 vfree(mtdblk->cache_data);
332         }
333
334         mutex_unlock(&mtdblks_lock);
335
336         pr_debug("ok\n");
337 }
338
339 static int mtdblock_flush(struct mtd_blktrans_dev *dev)
340 {
341         struct mtdblk_dev *mtdblk = container_of(dev, struct mtdblk_dev, mbd);
342
343         mutex_lock(&mtdblk->cache_mutex);
344         write_cached_data(mtdblk);
345         mutex_unlock(&mtdblk->cache_mutex);
346         mtd_sync(dev->mtd);
347         return 0;
348 }
349
350 static void mtdblock_add_mtd(struct mtd_blktrans_ops *tr, struct mtd_info *mtd)
351 {
352         struct mtdblk_dev *dev = kzalloc(sizeof(*dev), GFP_KERNEL);
353
354         if (!dev)
355                 return;
356
357         dev->mbd.mtd = mtd;
358         dev->mbd.devnum = mtd->index;
359
360         dev->mbd.size = mtd->size >> 9;
361         dev->mbd.tr = tr;
362
363         if (!(mtd->flags & MTD_WRITEABLE))
364                 dev->mbd.readonly = 1;
365
366         if (add_mtd_blktrans_dev(&dev->mbd))
367                 kfree(dev);
368 }
369
370 static void mtdblock_remove_dev(struct mtd_blktrans_dev *dev)
371 {
372         del_mtd_blktrans_dev(dev);
373 }
374
375 static struct mtd_blktrans_ops mtdblock_tr = {
376         .name           = "mtdblock",
377         .major          = MTD_BLOCK_MAJOR,
378         .part_bits      = 0,
379         .blksize        = 512,
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");
405 MODULE_AUTHOR("Nicolas Pitre <nico@fluxnic.net> et al.");
406 MODULE_DESCRIPTION("Caching read/erase/writeback block device emulation access to MTD devices");