1 /*
2 * block2mtd.c - create an mtd from a block device
3 *
4 * Copyright (C) 2001,2002 Simon Evans <spse@secret.org.uk>
5 * Copyright (C) 2004-2006 Joern Engel <joern@wh.fh-wedel.de>
6 *
7 * Licence: GPL
8 */
9
10 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
11
12 /*
13 * When the first attempt at device initialization fails, we may need to
14 * wait a little bit and retry. This timeout, by default 3 seconds, gives
15 * device time to start up. Required on BCM2708 and a few other chipsets.
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/bio.h>
24 #include <linux/pagemap.h>
25 #include <linux/list.h>
26 #include <linux/init.h>
27 #include <linux/mtd/mtd.h>
28 #include <linux/mutex.h>
29 #include <linux/mount.h>
30 #include <linux/slab.h>
31 #include <linux/major.h>
32
33 /* Info for the block device */
34 struct block2mtd_dev {
35 struct list_head list;
36 struct block_device *blkdev;
37 struct mtd_info mtd;
38 struct mutex write_mutex;
39 };
40
41
42 /* Static info about the MTD, used in cleanup_module */
43 static LIST_HEAD(blkmtd_device_list);
44
45
page_read(struct address_space * mapping,int index)46 static struct page *page_read(struct address_space *mapping, int index)
47 {
48 return read_mapping_page(mapping, index, NULL);
49 }
50
51 /* erase a specified part of the device */
_block2mtd_erase(struct block2mtd_dev * dev,loff_t to,size_t len)52 static int _block2mtd_erase(struct block2mtd_dev *dev, loff_t to, size_t len)
53 {
54 struct address_space *mapping = dev->blkdev->bd_inode->i_mapping;
55 struct page *page;
56 int index = to >> PAGE_SHIFT; // page index
57 int pages = len >> PAGE_SHIFT;
58 u_long *p;
59 u_long *max;
60
61 while (pages) {
62 page = page_read(mapping, index);
63 if (IS_ERR(page))
64 return PTR_ERR(page);
65
66 max = page_address(page) + PAGE_SIZE;
67 for (p=page_address(page); p<max; p++)
68 if (*p != -1UL) {
69 lock_page(page);
70 memset(page_address(page), 0xff, PAGE_SIZE);
71 set_page_dirty(page);
72 unlock_page(page);
73 balance_dirty_pages_ratelimited(mapping);
74 break;
75 }
76
77 page_cache_release(page);
78 pages--;
79 index++;
80 }
81 return 0;
82 }
block2mtd_erase(struct mtd_info * mtd,struct erase_info * instr)83 static int block2mtd_erase(struct mtd_info *mtd, struct erase_info *instr)
84 {
85 struct block2mtd_dev *dev = mtd->priv;
86 size_t from = instr->addr;
87 size_t len = instr->len;
88 int err;
89
90 instr->state = MTD_ERASING;
91 mutex_lock(&dev->write_mutex);
92 err = _block2mtd_erase(dev, from, len);
93 mutex_unlock(&dev->write_mutex);
94 if (err) {
95 pr_err("erase failed err = %d\n", err);
96 instr->state = MTD_ERASE_FAILED;
97 } else
98 instr->state = MTD_ERASE_DONE;
99
100 mtd_erase_callback(instr);
101 return err;
102 }
103
104
block2mtd_read(struct mtd_info * mtd,loff_t from,size_t len,size_t * retlen,u_char * buf)105 static int block2mtd_read(struct mtd_info *mtd, loff_t from, size_t len,
106 size_t *retlen, u_char *buf)
107 {
108 struct block2mtd_dev *dev = mtd->priv;
109 struct page *page;
110 int index = from >> PAGE_SHIFT;
111 int offset = from & (PAGE_SIZE-1);
112 int cpylen;
113
114 while (len) {
115 if ((offset + len) > PAGE_SIZE)
116 cpylen = PAGE_SIZE - offset; // multiple pages
117 else
118 cpylen = len; // this page
119 len = len - cpylen;
120
121 page = page_read(dev->blkdev->bd_inode->i_mapping, index);
122 if (IS_ERR(page))
123 return PTR_ERR(page);
124
125 memcpy(buf, page_address(page) + offset, cpylen);
126 page_cache_release(page);
127
128 if (retlen)
129 *retlen += cpylen;
130 buf += cpylen;
131 offset = 0;
132 index++;
133 }
134 return 0;
135 }
136
137
138 /* write data to the underlying device */
_block2mtd_write(struct block2mtd_dev * dev,const u_char * buf,loff_t to,size_t len,size_t * retlen)139 static int _block2mtd_write(struct block2mtd_dev *dev, const u_char *buf,
140 loff_t to, size_t len, size_t *retlen)
141 {
142 struct page *page;
143 struct address_space *mapping = dev->blkdev->bd_inode->i_mapping;
144 int index = to >> PAGE_SHIFT; // page index
145 int offset = to & ~PAGE_MASK; // page offset
146 int cpylen;
147
148 while (len) {
149 if ((offset+len) > PAGE_SIZE)
150 cpylen = PAGE_SIZE - offset; // multiple pages
151 else
152 cpylen = len; // this page
153 len = len - cpylen;
154
155 page = page_read(mapping, index);
156 if (IS_ERR(page))
157 return PTR_ERR(page);
158
159 if (memcmp(page_address(page)+offset, buf, cpylen)) {
160 lock_page(page);
161 memcpy(page_address(page) + offset, buf, cpylen);
162 set_page_dirty(page);
163 unlock_page(page);
164 balance_dirty_pages_ratelimited(mapping);
165 }
166 page_cache_release(page);
167
168 if (retlen)
169 *retlen += cpylen;
170
171 buf += cpylen;
172 offset = 0;
173 index++;
174 }
175 return 0;
176 }
177
178
block2mtd_write(struct mtd_info * mtd,loff_t to,size_t len,size_t * retlen,const u_char * buf)179 static int block2mtd_write(struct mtd_info *mtd, loff_t to, size_t len,
180 size_t *retlen, const u_char *buf)
181 {
182 struct block2mtd_dev *dev = mtd->priv;
183 int err;
184
185 mutex_lock(&dev->write_mutex);
186 err = _block2mtd_write(dev, buf, to, len, retlen);
187 mutex_unlock(&dev->write_mutex);
188 if (err > 0)
189 err = 0;
190 return err;
191 }
192
193
194 /* sync the device - wait until the write queue is empty */
block2mtd_sync(struct mtd_info * mtd)195 static void block2mtd_sync(struct mtd_info *mtd)
196 {
197 struct block2mtd_dev *dev = mtd->priv;
198 sync_blockdev(dev->blkdev);
199 return;
200 }
201
202
block2mtd_free_device(struct block2mtd_dev * dev)203 static void block2mtd_free_device(struct block2mtd_dev *dev)
204 {
205 if (!dev)
206 return;
207
208 kfree(dev->mtd.name);
209
210 if (dev->blkdev) {
211 invalidate_mapping_pages(dev->blkdev->bd_inode->i_mapping,
212 0, -1);
213 blkdev_put(dev->blkdev, FMODE_READ|FMODE_WRITE|FMODE_EXCL);
214 }
215
216 kfree(dev);
217 }
218
219
add_device(char * devname,int erase_size,int timeout)220 static struct block2mtd_dev *add_device(char *devname, int erase_size,
221 int timeout)
222 {
223 #ifndef MODULE
224 int i;
225 #endif
226 const fmode_t mode = FMODE_READ | FMODE_WRITE | FMODE_EXCL;
227 struct block_device *bdev = ERR_PTR(-ENODEV);
228 struct block2mtd_dev *dev;
229 char *name;
230
231 if (!devname)
232 return NULL;
233
234 dev = kzalloc(sizeof(struct block2mtd_dev), GFP_KERNEL);
235 if (!dev)
236 return NULL;
237
238 /* Get a handle on the device */
239 bdev = blkdev_get_by_path(devname, mode, dev);
240
241 #ifndef MODULE
242 /*
243 * We might not have the root device mounted at this point.
244 * Try to resolve the device name by other means.
245 */
246 for (i = 0; IS_ERR(bdev) && i <= timeout; i++) {
247 dev_t devt;
248
249 if (i)
250 /*
251 * Calling wait_for_device_probe in the first loop
252 * was not enough, sleep for a bit in subsequent
253 * go-arounds.
254 */
255 msleep(1000);
256 wait_for_device_probe();
257
258 devt = name_to_dev_t(devname);
259 if (!devt)
260 continue;
261 bdev = blkdev_get_by_dev(devt, mode, dev);
262 }
263 #endif
264
265 if (IS_ERR(bdev)) {
266 pr_err("error: cannot open device %s\n", devname);
267 goto err_free_block2mtd;
268 }
269 dev->blkdev = bdev;
270
271 if (MAJOR(bdev->bd_dev) == MTD_BLOCK_MAJOR) {
272 pr_err("attempting to use an MTD device as a block device\n");
273 goto err_free_block2mtd;
274 }
275
276 if ((long)dev->blkdev->bd_inode->i_size % erase_size) {
277 pr_err("erasesize must be a divisor of device size\n");
278 goto err_free_block2mtd;
279 }
280
281 mutex_init(&dev->write_mutex);
282
283 /* Setup the MTD structure */
284 /* make the name contain the block device in */
285 name = kasprintf(GFP_KERNEL, "block2mtd: %s", devname);
286 if (!name)
287 goto err_destroy_mutex;
288
289 dev->mtd.name = name;
290
291 dev->mtd.size = dev->blkdev->bd_inode->i_size & PAGE_MASK;
292 dev->mtd.erasesize = erase_size;
293 dev->mtd.writesize = 1;
294 dev->mtd.writebufsize = PAGE_SIZE;
295 dev->mtd.type = MTD_RAM;
296 dev->mtd.flags = MTD_CAP_RAM;
297 dev->mtd._erase = block2mtd_erase;
298 dev->mtd._write = block2mtd_write;
299 dev->mtd._sync = block2mtd_sync;
300 dev->mtd._read = block2mtd_read;
301 dev->mtd.priv = dev;
302 dev->mtd.owner = THIS_MODULE;
303
304 if (mtd_device_register(&dev->mtd, NULL, 0)) {
305 /* Device didn't get added, so free the entry */
306 goto err_destroy_mutex;
307 }
308
309 list_add(&dev->list, &blkmtd_device_list);
310 pr_info("mtd%d: [%s] erase_size = %dKiB [%d]\n",
311 dev->mtd.index,
312 dev->mtd.name + strlen("block2mtd: "),
313 dev->mtd.erasesize >> 10, dev->mtd.erasesize);
314 return dev;
315
316 err_destroy_mutex:
317 mutex_destroy(&dev->write_mutex);
318 err_free_block2mtd:
319 block2mtd_free_device(dev);
320 return NULL;
321 }
322
323
324 /* This function works similar to reguler strtoul. In addition, it
325 * allows some suffixes for a more human-readable number format:
326 * ki, Ki, kiB, KiB - multiply result with 1024
327 * Mi, MiB - multiply result with 1024^2
328 * Gi, GiB - multiply result with 1024^3
329 */
ustrtoul(const char * cp,char ** endp,unsigned int base)330 static int ustrtoul(const char *cp, char **endp, unsigned int base)
331 {
332 unsigned long result = simple_strtoul(cp, endp, base);
333 switch (**endp) {
334 case 'G' :
335 result *= 1024;
336 case 'M':
337 result *= 1024;
338 case 'K':
339 case 'k':
340 result *= 1024;
341 /* By dwmw2 editorial decree, "ki", "Mi" or "Gi" are to be used. */
342 if ((*endp)[1] == 'i') {
343 if ((*endp)[2] == 'B')
344 (*endp) += 3;
345 else
346 (*endp) += 2;
347 }
348 }
349 return result;
350 }
351
352
parse_num(size_t * num,const char * token)353 static int parse_num(size_t *num, const char *token)
354 {
355 char *endp;
356 size_t n;
357
358 n = (size_t) ustrtoul(token, &endp, 0);
359 if (*endp)
360 return -EINVAL;
361
362 *num = n;
363 return 0;
364 }
365
366
kill_final_newline(char * str)367 static inline void kill_final_newline(char *str)
368 {
369 char *newline = strrchr(str, '\n');
370 if (newline && !newline[1])
371 *newline = 0;
372 }
373
374
375 #ifndef MODULE
376 static int block2mtd_init_called = 0;
377 /* 80 for device, 12 for erase size */
378 static char block2mtd_paramline[80 + 12];
379 #endif
380
block2mtd_setup2(const char * val)381 static int block2mtd_setup2(const char *val)
382 {
383 /* 80 for device, 12 for erase size, 80 for name, 8 for timeout */
384 char buf[80 + 12 + 80 + 8];
385 char *str = buf;
386 char *token[2];
387 char *name;
388 size_t erase_size = PAGE_SIZE;
389 unsigned long timeout = MTD_DEFAULT_TIMEOUT;
390 int i, ret;
391
392 if (strnlen(val, sizeof(buf)) >= sizeof(buf)) {
393 pr_err("parameter too long\n");
394 return 0;
395 }
396
397 strcpy(str, val);
398 kill_final_newline(str);
399
400 for (i = 0; i < 2; i++)
401 token[i] = strsep(&str, ",");
402
403 if (str) {
404 pr_err("too many arguments\n");
405 return 0;
406 }
407
408 if (!token[0]) {
409 pr_err("no argument\n");
410 return 0;
411 }
412
413 name = token[0];
414 if (strlen(name) + 1 > 80) {
415 pr_err("device name too long\n");
416 return 0;
417 }
418
419 if (token[1]) {
420 ret = parse_num(&erase_size, token[1]);
421 if (ret) {
422 pr_err("illegal erase size\n");
423 return 0;
424 }
425 }
426
427 add_device(name, erase_size, timeout);
428
429 return 0;
430 }
431
432
block2mtd_setup(const char * val,struct kernel_param * kp)433 static int block2mtd_setup(const char *val, struct kernel_param *kp)
434 {
435 #ifdef MODULE
436 return block2mtd_setup2(val);
437 #else
438 /* If more parameters are later passed in via
439 /sys/module/block2mtd/parameters/block2mtd
440 and block2mtd_init() has already been called,
441 we can parse the argument now. */
442
443 if (block2mtd_init_called)
444 return block2mtd_setup2(val);
445
446 /* During early boot stage, we only save the parameters
447 here. We must parse them later: if the param passed
448 from kernel boot command line, block2mtd_setup() is
449 called so early that it is not possible to resolve
450 the device (even kmalloc() fails). Deter that work to
451 block2mtd_setup2(). */
452
453 strlcpy(block2mtd_paramline, val, sizeof(block2mtd_paramline));
454
455 return 0;
456 #endif
457 }
458
459
460 module_param_call(block2mtd, block2mtd_setup, NULL, NULL, 0200);
461 MODULE_PARM_DESC(block2mtd, "Device to use. \"block2mtd=<dev>[,<erasesize>]\"");
462
block2mtd_init(void)463 static int __init block2mtd_init(void)
464 {
465 int ret = 0;
466
467 #ifndef MODULE
468 if (strlen(block2mtd_paramline))
469 ret = block2mtd_setup2(block2mtd_paramline);
470 block2mtd_init_called = 1;
471 #endif
472
473 return ret;
474 }
475
476
block2mtd_exit(void)477 static void block2mtd_exit(void)
478 {
479 struct list_head *pos, *next;
480
481 /* Remove the MTD devices */
482 list_for_each_safe(pos, next, &blkmtd_device_list) {
483 struct block2mtd_dev *dev = list_entry(pos, typeof(*dev), list);
484 block2mtd_sync(&dev->mtd);
485 mtd_device_unregister(&dev->mtd);
486 mutex_destroy(&dev->write_mutex);
487 pr_info("mtd%d: [%s] removed\n",
488 dev->mtd.index,
489 dev->mtd.name + strlen("block2mtd: "));
490 list_del(&dev->list);
491 block2mtd_free_device(dev);
492 }
493 }
494
495 late_initcall(block2mtd_init);
496 module_exit(block2mtd_exit);
497
498 MODULE_LICENSE("GPL");
499 MODULE_AUTHOR("Joern Engel <joern@lazybastard.org>");
500 MODULE_DESCRIPTION("Emulate an MTD using a block device");
501