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9
10#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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16
17#define MTD_DEFAULT_TIMEOUT 3
18
19#include <linux/module.h>
20#include <linux/delay.h>
21#include <linux/fs.h>
22#include <linux/blkdev.h>
23#include <linux/backing-dev.h>
24#include <linux/bio.h>
25#include <linux/pagemap.h>
26#include <linux/list.h>
27#include <linux/init.h>
28#include <linux/mtd/mtd.h>
29#include <linux/mutex.h>
30#include <linux/mount.h>
31#include <linux/slab.h>
32#include <linux/major.h>
33
34
35struct block2mtd_dev {
36 struct list_head list;
37 struct block_device *blkdev;
38 struct mtd_info mtd;
39 struct mutex write_mutex;
40};
41
42
43
44static LIST_HEAD(blkmtd_device_list);
45
46
47static struct page *page_read(struct address_space *mapping, int index)
48{
49 return read_mapping_page(mapping, index, NULL);
50}
51
52
53static int _block2mtd_erase(struct block2mtd_dev *dev, loff_t to, size_t len)
54{
55 struct address_space *mapping = dev->blkdev->bd_inode->i_mapping;
56 struct page *page;
57 int index = to >> PAGE_SHIFT;
58 int pages = len >> PAGE_SHIFT;
59 u_long *p;
60 u_long *max;
61
62 while (pages) {
63 page = page_read(mapping, index);
64 if (IS_ERR(page))
65 return PTR_ERR(page);
66
67 max = page_address(page) + PAGE_SIZE;
68 for (p=page_address(page); p<max; p++)
69 if (*p != -1UL) {
70 lock_page(page);
71 memset(page_address(page), 0xff, PAGE_SIZE);
72 set_page_dirty(page);
73 unlock_page(page);
74 balance_dirty_pages_ratelimited(mapping);
75 break;
76 }
77
78 put_page(page);
79 pages--;
80 index++;
81 }
82 return 0;
83}
84static int block2mtd_erase(struct mtd_info *mtd, struct erase_info *instr)
85{
86 struct block2mtd_dev *dev = mtd->priv;
87 size_t from = instr->addr;
88 size_t len = instr->len;
89 int err;
90
91 instr->state = MTD_ERASING;
92 mutex_lock(&dev->write_mutex);
93 err = _block2mtd_erase(dev, from, len);
94 mutex_unlock(&dev->write_mutex);
95 if (err) {
96 pr_err("erase failed err = %d\n", err);
97 instr->state = MTD_ERASE_FAILED;
98 } else
99 instr->state = MTD_ERASE_DONE;
100
101 mtd_erase_callback(instr);
102 return err;
103}
104
105
106static int block2mtd_read(struct mtd_info *mtd, loff_t from, size_t len,
107 size_t *retlen, u_char *buf)
108{
109 struct block2mtd_dev *dev = mtd->priv;
110 struct page *page;
111 int index = from >> PAGE_SHIFT;
112 int offset = from & (PAGE_SIZE-1);
113 int cpylen;
114
115 while (len) {
116 if ((offset + len) > PAGE_SIZE)
117 cpylen = PAGE_SIZE - offset;
118 else
119 cpylen = len;
120 len = len - cpylen;
121
122 page = page_read(dev->blkdev->bd_inode->i_mapping, index);
123 if (IS_ERR(page))
124 return PTR_ERR(page);
125
126 memcpy(buf, page_address(page) + offset, cpylen);
127 put_page(page);
128
129 if (retlen)
130 *retlen += cpylen;
131 buf += cpylen;
132 offset = 0;
133 index++;
134 }
135 return 0;
136}
137
138
139
140static int _block2mtd_write(struct block2mtd_dev *dev, const u_char *buf,
141 loff_t to, size_t len, size_t *retlen)
142{
143 struct page *page;
144 struct address_space *mapping = dev->blkdev->bd_inode->i_mapping;
145 int index = to >> PAGE_SHIFT;
146 int offset = to & ~PAGE_MASK;
147 int cpylen;
148
149 while (len) {
150 if ((offset+len) > PAGE_SIZE)
151 cpylen = PAGE_SIZE - offset;
152 else
153 cpylen = len;
154 len = len - cpylen;
155
156 page = page_read(mapping, index);
157 if (IS_ERR(page))
158 return PTR_ERR(page);
159
160 if (memcmp(page_address(page)+offset, buf, cpylen)) {
161 lock_page(page);
162 memcpy(page_address(page) + offset, buf, cpylen);
163 set_page_dirty(page);
164 unlock_page(page);
165 balance_dirty_pages_ratelimited(mapping);
166 }
167 put_page(page);
168
169 if (retlen)
170 *retlen += cpylen;
171
172 buf += cpylen;
173 offset = 0;
174 index++;
175 }
176 return 0;
177}
178
179
180static int block2mtd_write(struct mtd_info *mtd, loff_t to, size_t len,
181 size_t *retlen, const u_char *buf)
182{
183 struct block2mtd_dev *dev = mtd->priv;
184 int err;
185
186 mutex_lock(&dev->write_mutex);
187 err = _block2mtd_write(dev, buf, to, len, retlen);
188 mutex_unlock(&dev->write_mutex);
189 if (err > 0)
190 err = 0;
191 return err;
192}
193
194
195
196static void block2mtd_sync(struct mtd_info *mtd)
197{
198 struct block2mtd_dev *dev = mtd->priv;
199 sync_blockdev(dev->blkdev);
200 return;
201}
202
203
204static void block2mtd_free_device(struct block2mtd_dev *dev)
205{
206 if (!dev)
207 return;
208
209 kfree(dev->mtd.name);
210
211 if (dev->blkdev) {
212 invalidate_mapping_pages(dev->blkdev->bd_inode->i_mapping,
213 0, -1);
214 blkdev_put(dev->blkdev, FMODE_READ|FMODE_WRITE|FMODE_EXCL);
215 }
216
217 kfree(dev);
218}
219
220
221static struct block2mtd_dev *add_device(char *devname, int erase_size,
222 int timeout)
223{
224#ifndef MODULE
225 int i;
226#endif
227 const fmode_t mode = FMODE_READ | FMODE_WRITE | FMODE_EXCL;
228 struct block_device *bdev = ERR_PTR(-ENODEV);
229 struct block2mtd_dev *dev;
230 char *name;
231
232 if (!devname)
233 return NULL;
234
235 dev = kzalloc(sizeof(struct block2mtd_dev), GFP_KERNEL);
236 if (!dev)
237 return NULL;
238
239
240 bdev = blkdev_get_by_path(devname, mode, dev);
241
242#ifndef MODULE
243
244
245
246
247 for (i = 0; IS_ERR(bdev) && i <= timeout; i++) {
248 dev_t devt;
249
250 if (i)
251
252
253
254
255
256 msleep(1000);
257 wait_for_device_probe();
258
259 devt = name_to_dev_t(devname);
260 if (!devt)
261 continue;
262 bdev = blkdev_get_by_dev(devt, mode, dev);
263 }
264#endif
265
266 if (IS_ERR(bdev)) {
267 pr_err("error: cannot open device %s\n", devname);
268 goto err_free_block2mtd;
269 }
270 dev->blkdev = bdev;
271
272 if (MAJOR(bdev->bd_dev) == MTD_BLOCK_MAJOR) {
273 pr_err("attempting to use an MTD device as a block device\n");
274 goto err_free_block2mtd;
275 }
276
277 if ((long)dev->blkdev->bd_inode->i_size % erase_size) {
278 pr_err("erasesize must be a divisor of device size\n");
279 goto err_free_block2mtd;
280 }
281
282 mutex_init(&dev->write_mutex);
283
284
285
286 name = kasprintf(GFP_KERNEL, "block2mtd: %s", devname);
287 if (!name)
288 goto err_destroy_mutex;
289
290 dev->mtd.name = name;
291
292 dev->mtd.size = dev->blkdev->bd_inode->i_size & PAGE_MASK;
293 dev->mtd.erasesize = erase_size;
294 dev->mtd.writesize = 1;
295 dev->mtd.writebufsize = PAGE_SIZE;
296 dev->mtd.type = MTD_RAM;
297 dev->mtd.flags = MTD_CAP_RAM;
298 dev->mtd._erase = block2mtd_erase;
299 dev->mtd._write = block2mtd_write;
300 dev->mtd._sync = block2mtd_sync;
301 dev->mtd._read = block2mtd_read;
302 dev->mtd.priv = dev;
303 dev->mtd.owner = THIS_MODULE;
304
305 if (mtd_device_register(&dev->mtd, NULL, 0)) {
306
307 goto err_destroy_mutex;
308 }
309
310 list_add(&dev->list, &blkmtd_device_list);
311 pr_info("mtd%d: [%s] erase_size = %dKiB [%d]\n",
312 dev->mtd.index,
313 dev->mtd.name + strlen("block2mtd: "),
314 dev->mtd.erasesize >> 10, dev->mtd.erasesize);
315 return dev;
316
317err_destroy_mutex:
318 mutex_destroy(&dev->write_mutex);
319err_free_block2mtd:
320 block2mtd_free_device(dev);
321 return NULL;
322}
323
324
325
326
327
328
329
330
331static int ustrtoul(const char *cp, char **endp, unsigned int base)
332{
333 unsigned long result = simple_strtoul(cp, endp, base);
334 switch (**endp) {
335 case 'G' :
336 result *= 1024;
337 case 'M':
338 result *= 1024;
339 case 'K':
340 case 'k':
341 result *= 1024;
342
343 if ((*endp)[1] == 'i') {
344 if ((*endp)[2] == 'B')
345 (*endp) += 3;
346 else
347 (*endp) += 2;
348 }
349 }
350 return result;
351}
352
353
354static int parse_num(size_t *num, const char *token)
355{
356 char *endp;
357 size_t n;
358
359 n = (size_t) ustrtoul(token, &endp, 0);
360 if (*endp)
361 return -EINVAL;
362
363 *num = n;
364 return 0;
365}
366
367
368static inline void kill_final_newline(char *str)
369{
370 char *newline = strrchr(str, '\n');
371 if (newline && !newline[1])
372 *newline = 0;
373}
374
375
376#ifndef MODULE
377static int block2mtd_init_called = 0;
378
379static char block2mtd_paramline[80 + 12];
380#endif
381
382static int block2mtd_setup2(const char *val)
383{
384
385 char buf[80 + 12 + 80 + 8];
386 char *str = buf;
387 char *token[2];
388 char *name;
389 size_t erase_size = PAGE_SIZE;
390 unsigned long timeout = MTD_DEFAULT_TIMEOUT;
391 int i, ret;
392
393 if (strnlen(val, sizeof(buf)) >= sizeof(buf)) {
394 pr_err("parameter too long\n");
395 return 0;
396 }
397
398 strcpy(str, val);
399 kill_final_newline(str);
400
401 for (i = 0; i < 2; i++)
402 token[i] = strsep(&str, ",");
403
404 if (str) {
405 pr_err("too many arguments\n");
406 return 0;
407 }
408
409 if (!token[0]) {
410 pr_err("no argument\n");
411 return 0;
412 }
413
414 name = token[0];
415 if (strlen(name) + 1 > 80) {
416 pr_err("device name too long\n");
417 return 0;
418 }
419
420 if (token[1]) {
421 ret = parse_num(&erase_size, token[1]);
422 if (ret) {
423 pr_err("illegal erase size\n");
424 return 0;
425 }
426 }
427
428 add_device(name, erase_size, timeout);
429
430 return 0;
431}
432
433
434static int block2mtd_setup(const char *val, struct kernel_param *kp)
435{
436#ifdef MODULE
437 return block2mtd_setup2(val);
438#else
439
440
441
442
443
444 if (block2mtd_init_called)
445 return block2mtd_setup2(val);
446
447
448
449
450
451
452
453
454 strlcpy(block2mtd_paramline, val, sizeof(block2mtd_paramline));
455
456 return 0;
457#endif
458}
459
460
461module_param_call(block2mtd, block2mtd_setup, NULL, NULL, 0200);
462MODULE_PARM_DESC(block2mtd, "Device to use. \"block2mtd=<dev>[,<erasesize>]\"");
463
464static int __init block2mtd_init(void)
465{
466 int ret = 0;
467
468#ifndef MODULE
469 if (strlen(block2mtd_paramline))
470 ret = block2mtd_setup2(block2mtd_paramline);
471 block2mtd_init_called = 1;
472#endif
473
474 return ret;
475}
476
477
478static void block2mtd_exit(void)
479{
480 struct list_head *pos, *next;
481
482
483 list_for_each_safe(pos, next, &blkmtd_device_list) {
484 struct block2mtd_dev *dev = list_entry(pos, typeof(*dev), list);
485 block2mtd_sync(&dev->mtd);
486 mtd_device_unregister(&dev->mtd);
487 mutex_destroy(&dev->write_mutex);
488 pr_info("mtd%d: [%s] removed\n",
489 dev->mtd.index,
490 dev->mtd.name + strlen("block2mtd: "));
491 list_del(&dev->list);
492 block2mtd_free_device(dev);
493 }
494}
495
496late_initcall(block2mtd_init);
497module_exit(block2mtd_exit);
498
499MODULE_LICENSE("GPL");
500MODULE_AUTHOR("Joern Engel <joern@lazybastard.org>");
501MODULE_DESCRIPTION("Emulate an MTD using a block device");
502