2 * $Id: block2mtd.c,v 1.30 2005/11/29 14:48:32 gleixner Exp $
4 * block2mtd.c - create an mtd from a block device
6 * Copyright (C) 2001,2002 Simon Evans <spse@secret.org.uk>
7 * Copyright (C) 2004-2006 Jörn Engel <joern@wh.fh-wedel.de>
11 #include <linux/module.h>
13 #include <linux/blkdev.h>
14 #include <linux/bio.h>
15 #include <linux/pagemap.h>
16 #include <linux/list.h>
17 #include <linux/init.h>
18 #include <linux/mtd/mtd.h>
19 #include <linux/buffer_head.h>
20 #include <linux/mutex.h>
21 #include <linux/mount.h>
23 #define VERSION "$Revision: 1.30 $"
26 #define ERROR(fmt, args...) printk(KERN_ERR "block2mtd: " fmt "\n" , ## args)
27 #define INFO(fmt, args...) printk(KERN_INFO "block2mtd: " fmt "\n" , ## args)
30 /* Info for the block device */
31 struct block2mtd_dev {
32 struct list_head list;
33 struct block_device *blkdev;
35 struct mutex write_mutex;
39 /* Static info about the MTD, used in cleanup_module */
40 static LIST_HEAD(blkmtd_device_list);
43 static struct page* page_read(struct address_space *mapping, int index)
45 filler_t *filler = (filler_t*)mapping->a_ops->readpage;
46 return read_cache_page(mapping, index, filler, NULL);
50 /* erase a specified part of the device */
51 static int _block2mtd_erase(struct block2mtd_dev *dev, loff_t to, size_t len)
53 struct address_space *mapping = dev->blkdev->bd_inode->i_mapping;
55 int index = to >> PAGE_SHIFT; // page index
56 int pages = len >> PAGE_SHIFT;
61 page = page_read(mapping, index);
67 max = page_address(page) + PAGE_SIZE;
68 for (p=page_address(page); p<max; p++)
71 memset(page_address(page), 0xff, PAGE_SIZE);
77 page_cache_release(page);
83 static int block2mtd_erase(struct mtd_info *mtd, struct erase_info *instr)
85 struct block2mtd_dev *dev = mtd->priv;
86 size_t from = instr->addr;
87 size_t len = instr->len;
90 instr->state = MTD_ERASING;
91 mutex_lock(&dev->write_mutex);
92 err = _block2mtd_erase(dev, from, len);
93 mutex_unlock(&dev->write_mutex);
95 ERROR("erase failed err = %d", err);
96 instr->state = MTD_ERASE_FAILED;
98 instr->state = MTD_ERASE_DONE;
100 instr->state = MTD_ERASE_DONE;
101 mtd_erase_callback(instr);
106 static int block2mtd_read(struct mtd_info *mtd, loff_t from, size_t len,
107 size_t *retlen, u_char *buf)
109 struct block2mtd_dev *dev = mtd->priv;
111 int index = from >> PAGE_SHIFT;
112 int offset = from & (PAGE_SIZE-1);
115 if (from > mtd->size)
117 if (from + len > mtd->size)
118 len = mtd->size - from;
124 if ((offset + len) > PAGE_SIZE)
125 cpylen = PAGE_SIZE - offset; // multiple pages
127 cpylen = len; // this page
130 page = page_read(dev->blkdev->bd_inode->i_mapping, index);
134 return PTR_ERR(page);
136 memcpy(buf, page_address(page) + offset, cpylen);
137 page_cache_release(page);
149 /* write data to the underlying device */
150 static int _block2mtd_write(struct block2mtd_dev *dev, const u_char *buf,
151 loff_t to, size_t len, size_t *retlen)
154 struct address_space *mapping = dev->blkdev->bd_inode->i_mapping;
155 int index = to >> PAGE_SHIFT; // page index
156 int offset = to & ~PAGE_MASK; // page offset
162 if ((offset+len) > PAGE_SIZE)
163 cpylen = PAGE_SIZE - offset; // multiple pages
165 cpylen = len; // this page
168 page = page_read(mapping, index);
172 return PTR_ERR(page);
174 if (memcmp(page_address(page)+offset, buf, cpylen)) {
176 memcpy(page_address(page) + offset, buf, cpylen);
177 set_page_dirty(page);
180 page_cache_release(page);
193 static int block2mtd_write(struct mtd_info *mtd, loff_t to, size_t len,
194 size_t *retlen, const u_char *buf)
196 struct block2mtd_dev *dev = mtd->priv;
203 if (to + len > mtd->size)
204 len = mtd->size - to;
206 mutex_lock(&dev->write_mutex);
207 err = _block2mtd_write(dev, buf, to, len, retlen);
208 mutex_unlock(&dev->write_mutex);
215 /* sync the device - wait until the write queue is empty */
216 static void block2mtd_sync(struct mtd_info *mtd)
218 struct block2mtd_dev *dev = mtd->priv;
219 sync_blockdev(dev->blkdev);
224 static void block2mtd_free_device(struct block2mtd_dev *dev)
229 kfree(dev->mtd.name);
232 invalidate_mapping_pages(dev->blkdev->bd_inode->i_mapping,
234 close_bdev_excl(dev->blkdev);
241 /* FIXME: ensure that mtd->size % erase_size == 0 */
242 static struct block2mtd_dev *add_device(char *devname, int erase_size)
244 struct block_device *bdev;
245 struct block2mtd_dev *dev;
250 dev = kzalloc(sizeof(struct block2mtd_dev), GFP_KERNEL);
254 /* Get a handle on the device */
255 bdev = open_bdev_excl(devname, O_RDWR, NULL);
259 /* We might not have rootfs mounted at this point. Try
260 to resolve the device name by other means. */
262 dev_t devt = name_to_dev_t(devname);
264 bdev = open_by_devnum(devt, FMODE_WRITE | FMODE_READ);
270 ERROR("error: cannot open device %s", devname);
275 if (MAJOR(bdev->bd_dev) == MTD_BLOCK_MAJOR) {
276 ERROR("attempting to use an MTD device as a block device");
280 mutex_init(&dev->write_mutex);
282 /* Setup the MTD structure */
283 /* make the name contain the block device in */
284 dev->mtd.name = kmalloc(sizeof("block2mtd: ") + strlen(devname),
289 sprintf(dev->mtd.name, "block2mtd: %s", devname);
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.type = MTD_RAM;
295 dev->mtd.flags = MTD_CAP_RAM;
296 dev->mtd.erase = block2mtd_erase;
297 dev->mtd.write = block2mtd_write;
298 dev->mtd.writev = default_mtd_writev;
299 dev->mtd.sync = block2mtd_sync;
300 dev->mtd.read = block2mtd_read;
302 dev->mtd.owner = THIS_MODULE;
304 if (add_mtd_device(&dev->mtd)) {
305 /* Device didnt get added, so free the entry */
308 list_add(&dev->list, &blkmtd_device_list);
309 INFO("mtd%d: [%s] erase_size = %dKiB [%d]", dev->mtd.index,
310 dev->mtd.name + strlen("blkmtd: "),
311 dev->mtd.erasesize >> 10, dev->mtd.erasesize);
315 block2mtd_free_device(dev);
320 /* This function works similar to reguler strtoul. In addition, it
321 * allows some suffixes for a more human-readable number format:
322 * ki, Ki, kiB, KiB - multiply result with 1024
323 * Mi, MiB - multiply result with 1024^2
324 * Gi, GiB - multiply result with 1024^3
326 static int ustrtoul(const char *cp, char **endp, unsigned int base)
328 unsigned long result = simple_strtoul(cp, endp, base);
337 /* By dwmw2 editorial decree, "ki", "Mi" or "Gi" are to be used. */
338 if ((*endp)[1] == 'i') {
339 if ((*endp)[2] == 'B')
349 static int parse_num(size_t *num, const char *token)
354 n = (size_t) ustrtoul(token, &endp, 0);
363 static inline void kill_final_newline(char *str)
365 char *newline = strrchr(str, '\n');
366 if (newline && !newline[1])
371 #define parse_err(fmt, args...) do { \
372 ERROR("block2mtd: " fmt "\n", ## args); \
377 static int block2mtd_init_called = 0;
378 static __initdata char block2mtd_paramline[80 + 12]; /* 80 for device, 12 for erase size */
382 static int block2mtd_setup2(const char *val)
384 char buf[80 + 12]; /* 80 for device, 12 for erase size */
388 size_t erase_size = PAGE_SIZE;
391 if (strnlen(val, sizeof(buf)) >= sizeof(buf))
392 parse_err("parameter too long");
395 kill_final_newline(str);
397 for (i = 0; i < 2; i++)
398 token[i] = strsep(&str, ",");
401 parse_err("too many arguments");
404 parse_err("no argument");
407 if (strlen(name) + 1 > 80)
408 parse_err("device name too long");
411 ret = parse_num(&erase_size, token[1]);
414 parse_err("illegal erase size");
418 add_device(name, erase_size);
424 static int block2mtd_setup(const char *val, struct kernel_param *kp)
427 return block2mtd_setup2(val);
429 /* If more parameters are later passed in via
430 /sys/module/block2mtd/parameters/block2mtd
431 and block2mtd_init() has already been called,
432 we can parse the argument now. */
434 if (block2mtd_init_called)
435 return block2mtd_setup2(val);
437 /* During early boot stage, we only save the parameters
438 here. We must parse them later: if the param passed
439 from kernel boot command line, block2mtd_setup() is
440 called so early that it is not possible to resolve
441 the device (even kmalloc() fails). Deter that work to
442 block2mtd_setup2(). */
444 strlcpy(block2mtd_paramline, val, sizeof(block2mtd_paramline));
451 module_param_call(block2mtd, block2mtd_setup, NULL, NULL, 0200);
452 MODULE_PARM_DESC(block2mtd, "Device to use. \"block2mtd=<dev>[,<erasesize>]\"");
454 static int __init block2mtd_init(void)
457 INFO("version " VERSION);
460 if (strlen(block2mtd_paramline))
461 ret = block2mtd_setup2(block2mtd_paramline);
462 block2mtd_init_called = 1;
469 static void __devexit block2mtd_exit(void)
471 struct list_head *pos, *next;
473 /* Remove the MTD devices */
474 list_for_each_safe(pos, next, &blkmtd_device_list) {
475 struct block2mtd_dev *dev = list_entry(pos, typeof(*dev), list);
476 block2mtd_sync(&dev->mtd);
477 del_mtd_device(&dev->mtd);
478 INFO("mtd%d: [%s] removed", dev->mtd.index,
479 dev->mtd.name + strlen("blkmtd: "));
480 list_del(&dev->list);
481 block2mtd_free_device(dev);
486 module_init(block2mtd_init);
487 module_exit(block2mtd_exit);
489 MODULE_LICENSE("GPL");
490 MODULE_AUTHOR("Simon Evans <spse@secret.org.uk> and others");
491 MODULE_DESCRIPTION("Emulate an MTD using a block device");