1/*
2 * $Id: block2mtd.c,v 1.1.1.1 2007/08/03 18:52:43 Exp $
3 *
4 * block2mtd.c - create an mtd from a block device
5 *
6 * Copyright (C) 2001,2002	Simon Evans <spse@secret.org.uk>
7 * Copyright (C) 2004-2006	J��rn Engel <joern@wh.fh-wedel.de>
8 *
9 * Licence: GPL
10 */
11#include <linux/module.h>
12#include <linux/fs.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>
22
23#define VERSION "$Revision: 1.1.1.1 $"
24
25
26#define ERROR(fmt, args...) printk(KERN_ERR "block2mtd: " fmt "\n" , ## args)
27#define INFO(fmt, args...) printk(KERN_INFO "block2mtd: " fmt "\n" , ## args)
28
29
30/* Info for the block device */
31struct block2mtd_dev {
32	struct list_head list;
33	struct block_device *blkdev;
34	struct mtd_info mtd;
35	struct mutex write_mutex;
36};
37
38
39/* Static info about the MTD, used in cleanup_module */
40static LIST_HEAD(blkmtd_device_list);
41
42
43static struct page *page_read(struct address_space *mapping, int index)
44{
45	return read_mapping_page(mapping, index, NULL);
46}
47
48/* erase a specified part of the device */
49static int _block2mtd_erase(struct block2mtd_dev *dev, loff_t to, size_t len)
50{
51	struct address_space *mapping = dev->blkdev->bd_inode->i_mapping;
52	struct page *page;
53	int index = to >> PAGE_SHIFT;	// page index
54	int pages = len >> PAGE_SHIFT;
55	u_long *p;
56	u_long *max;
57
58	while (pages) {
59		page = page_read(mapping, index);
60		if (!page)
61			return -ENOMEM;
62		if (IS_ERR(page))
63			return PTR_ERR(page);
64
65		max = page_address(page) + PAGE_SIZE;
66		for (p=page_address(page); p<max; p++)
67			if (*p != -1UL) {
68				lock_page(page);
69				memset(page_address(page), 0xff, PAGE_SIZE);
70				set_page_dirty(page);
71				unlock_page(page);
72				break;
73			}
74
75		page_cache_release(page);
76		pages--;
77		index++;
78	}
79	return 0;
80}
81static int block2mtd_erase(struct mtd_info *mtd, struct erase_info *instr)
82{
83	struct block2mtd_dev *dev = mtd->priv;
84	size_t from = instr->addr;
85	size_t len = instr->len;
86	int err;
87
88	instr->state = MTD_ERASING;
89	mutex_lock(&dev->write_mutex);
90	err = _block2mtd_erase(dev, from, len);
91	mutex_unlock(&dev->write_mutex);
92	if (err) {
93		ERROR("erase failed err = %d", err);
94		instr->state = MTD_ERASE_FAILED;
95	} else
96		instr->state = MTD_ERASE_DONE;
97
98	instr->state = MTD_ERASE_DONE;
99	mtd_erase_callback(instr);
100	return err;
101}
102
103
104static int block2mtd_read(struct mtd_info *mtd, loff_t from, size_t len,
105		size_t *retlen, u_char *buf)
106{
107	struct block2mtd_dev *dev = mtd->priv;
108	struct page *page;
109	int index = from >> PAGE_SHIFT;
110	int offset = from & (PAGE_SIZE-1);
111	int cpylen;
112
113	if (from > mtd->size)
114		return -EINVAL;
115	if (from + len > mtd->size)
116		len = mtd->size - from;
117
118	if (retlen)
119		*retlen = 0;
120
121	while (len) {
122		if ((offset + len) > PAGE_SIZE)
123			cpylen = PAGE_SIZE - offset;	// multiple pages
124		else
125			cpylen = len;	// this page
126		len = len - cpylen;
127
128		page = page_read(dev->blkdev->bd_inode->i_mapping, index);
129		if (!page)
130			return -ENOMEM;
131		if (IS_ERR(page))
132			return PTR_ERR(page);
133
134		memcpy(buf, page_address(page) + offset, cpylen);
135		page_cache_release(page);
136
137		if (retlen)
138			*retlen += cpylen;
139		buf += cpylen;
140		offset = 0;
141		index++;
142	}
143	return 0;
144}
145
146
147/* write data to the underlying device */
148static int _block2mtd_write(struct block2mtd_dev *dev, const u_char *buf,
149		loff_t to, size_t len, size_t *retlen)
150{
151	struct page *page;
152	struct address_space *mapping = dev->blkdev->bd_inode->i_mapping;
153	int index = to >> PAGE_SHIFT;	// page index
154	int offset = to & ~PAGE_MASK;	// page offset
155	int cpylen;
156
157	if (retlen)
158		*retlen = 0;
159	while (len) {
160		if ((offset+len) > PAGE_SIZE)
161			cpylen = PAGE_SIZE - offset;	// multiple pages
162		else
163			cpylen = len;			// this page
164		len = len - cpylen;
165
166		page = page_read(mapping, index);
167		if (!page)
168			return -ENOMEM;
169		if (IS_ERR(page))
170			return PTR_ERR(page);
171
172		if (memcmp(page_address(page)+offset, buf, cpylen)) {
173			lock_page(page);
174			memcpy(page_address(page) + offset, buf, cpylen);
175			set_page_dirty(page);
176			unlock_page(page);
177		}
178		page_cache_release(page);
179
180		if (retlen)
181			*retlen += cpylen;
182
183		buf += cpylen;
184		offset = 0;
185		index++;
186	}
187	return 0;
188}
189
190
191static int block2mtd_write(struct mtd_info *mtd, loff_t to, size_t len,
192		size_t *retlen, const u_char *buf)
193{
194	struct block2mtd_dev *dev = mtd->priv;
195	int err;
196
197	if (!len)
198		return 0;
199	if (to >= mtd->size)
200		return -ENOSPC;
201	if (to + len > mtd->size)
202		len = mtd->size - to;
203
204	mutex_lock(&dev->write_mutex);
205	err = _block2mtd_write(dev, buf, to, len, retlen);
206	mutex_unlock(&dev->write_mutex);
207	if (err > 0)
208		err = 0;
209	return err;
210}
211
212
213/* sync the device - wait until the write queue is empty */
214static void block2mtd_sync(struct mtd_info *mtd)
215{
216	struct block2mtd_dev *dev = mtd->priv;
217	sync_blockdev(dev->blkdev);
218	return;
219}
220
221
222static void block2mtd_free_device(struct block2mtd_dev *dev)
223{
224	if (!dev)
225		return;
226
227	kfree(dev->mtd.name);
228
229	if (dev->blkdev) {
230		invalidate_mapping_pages(dev->blkdev->bd_inode->i_mapping,
231					0, -1);
232		close_bdev_excl(dev->blkdev);
233	}
234
235	kfree(dev);
236}
237
238
239static struct block2mtd_dev *add_device(char *devname, int erase_size)
240{
241	struct block_device *bdev;
242	struct block2mtd_dev *dev;
243
244	if (!devname)
245		return NULL;
246
247	dev = kzalloc(sizeof(struct block2mtd_dev), GFP_KERNEL);
248	if (!dev)
249		return NULL;
250
251	/* Get a handle on the device */
252	bdev = open_bdev_excl(devname, O_RDWR, NULL);
253#ifndef MODULE
254	if (IS_ERR(bdev)) {
255
256		/* We might not have rootfs mounted at this point. Try
257		   to resolve the device name by other means. */
258
259		dev_t devt = name_to_dev_t(devname);
260		if (devt) {
261			bdev = open_by_devnum(devt, FMODE_WRITE | FMODE_READ);
262		}
263	}
264#endif
265
266	if (IS_ERR(bdev)) {
267		ERROR("error: cannot open device %s", devname);
268		goto devinit_err;
269	}
270	dev->blkdev = bdev;
271
272	if (MAJOR(bdev->bd_dev) == MTD_BLOCK_MAJOR) {
273		ERROR("attempting to use an MTD device as a block device");
274		goto devinit_err;
275	}
276
277	mutex_init(&dev->write_mutex);
278
279	/* Setup the MTD structure */
280	/* make the name contain the block device in */
281	dev->mtd.name = kmalloc(sizeof("block2mtd: ") + strlen(devname),
282			GFP_KERNEL);
283	if (!dev->mtd.name)
284		goto devinit_err;
285
286	sprintf(dev->mtd.name, "block2mtd: %s", devname);
287
288	dev->mtd.size = dev->blkdev->bd_inode->i_size & PAGE_MASK;
289	dev->mtd.erasesize = erase_size;
290	dev->mtd.writesize = 1;
291	dev->mtd.type = MTD_RAM;
292	dev->mtd.flags = MTD_CAP_RAM;
293	dev->mtd.erase = block2mtd_erase;
294	dev->mtd.write = block2mtd_write;
295	dev->mtd.writev = default_mtd_writev;
296	dev->mtd.sync = block2mtd_sync;
297	dev->mtd.read = block2mtd_read;
298	dev->mtd.priv = dev;
299	dev->mtd.owner = THIS_MODULE;
300
301	if (add_mtd_device(&dev->mtd)) {
302		/* Device didnt get added, so free the entry */
303		goto devinit_err;
304	}
305	list_add(&dev->list, &blkmtd_device_list);
306	INFO("mtd%d: [%s] erase_size = %dKiB [%d]", dev->mtd.index,
307			dev->mtd.name + strlen("blkmtd: "),
308			dev->mtd.erasesize >> 10, dev->mtd.erasesize);
309	return dev;
310
311devinit_err:
312	block2mtd_free_device(dev);
313	return NULL;
314}
315
316
317/* This function works similar to reguler strtoul.  In addition, it
318 * allows some suffixes for a more human-readable number format:
319 * ki, Ki, kiB, KiB	- multiply result with 1024
320 * Mi, MiB		- multiply result with 1024^2
321 * Gi, GiB		- multiply result with 1024^3
322 */
323static int ustrtoul(const char *cp, char **endp, unsigned int base)
324{
325	unsigned long result = simple_strtoul(cp, endp, base);
326	switch (**endp) {
327	case 'G' :
328		result *= 1024;
329	case 'M':
330		result *= 1024;
331	case 'K':
332	case 'k':
333		result *= 1024;
334	/* By dwmw2 editorial decree, "ki", "Mi" or "Gi" are to be used. */
335		if ((*endp)[1] == 'i') {
336			if ((*endp)[2] == 'B')
337				(*endp) += 3;
338			else
339				(*endp) += 2;
340		}
341	}
342	return result;
343}
344
345
346static int parse_num(size_t *num, const char *token)
347{
348	char *endp;
349	size_t n;
350
351	n = (size_t) ustrtoul(token, &endp, 0);
352	if (*endp)
353		return -EINVAL;
354
355	*num = n;
356	return 0;
357}
358
359
360static inline void kill_final_newline(char *str)
361{
362	char *newline = strrchr(str, '\n');
363	if (newline && !newline[1])
364		*newline = 0;
365}
366
367
368#define parse_err(fmt, args...) do {		\
369	ERROR("block2mtd: " fmt "\n", ## args);	\
370	return 0;				\
371} while (0)
372
373#ifndef MODULE
374static int block2mtd_init_called = 0;
375static char block2mtd_paramline[80 + 12]; /* 80 for device, 12 for erase size */
376#endif
377
378
379static int block2mtd_setup2(const char *val)
380{
381	char buf[80 + 12]; /* 80 for device, 12 for erase size */
382	char *str = buf;
383	char *token[2];
384	char *name;
385	size_t erase_size = PAGE_SIZE;
386	int i, ret;
387
388	if (strnlen(val, sizeof(buf)) >= sizeof(buf))
389		parse_err("parameter too long");
390
391	strcpy(str, val);
392	kill_final_newline(str);
393
394	for (i = 0; i < 2; i++)
395		token[i] = strsep(&str, ",");
396
397	if (str)
398		parse_err("too many arguments");
399
400	if (!token[0])
401		parse_err("no argument");
402
403	name = token[0];
404	if (strlen(name) + 1 > 80)
405		parse_err("device name too long");
406
407	if (token[1]) {
408		ret = parse_num(&erase_size, token[1]);
409		if (ret) {
410			kfree(name);
411			parse_err("illegal erase size");
412		}
413	}
414
415	add_device(name, erase_size);
416
417	return 0;
418}
419
420
421static int block2mtd_setup(const char *val, struct kernel_param *kp)
422{
423#ifdef MODULE
424	return block2mtd_setup2(val);
425#else
426	/* If more parameters are later passed in via
427	   /sys/module/block2mtd/parameters/block2mtd
428	   and block2mtd_init() has already been called,
429	   we can parse the argument now. */
430
431	if (block2mtd_init_called)
432		return block2mtd_setup2(val);
433
434	/* During early boot stage, we only save the parameters
435	   here. We must parse them later: if the param passed
436	   from kernel boot command line, block2mtd_setup() is
437	   called so early that it is not possible to resolve
438	   the device (even kmalloc() fails). Deter that work to
439	   block2mtd_setup2(). */
440
441	strlcpy(block2mtd_paramline, val, sizeof(block2mtd_paramline));
442
443	return 0;
444#endif
445}
446
447
448module_param_call(block2mtd, block2mtd_setup, NULL, NULL, 0200);
449MODULE_PARM_DESC(block2mtd, "Device to use. \"block2mtd=<dev>[,<erasesize>]\"");
450
451static int __init block2mtd_init(void)
452{
453	int ret = 0;
454	INFO("version " VERSION);
455
456#ifndef MODULE
457	if (strlen(block2mtd_paramline))
458		ret = block2mtd_setup2(block2mtd_paramline);
459	block2mtd_init_called = 1;
460#endif
461
462	return ret;
463}
464
465
466static void __devexit block2mtd_exit(void)
467{
468	struct list_head *pos, *next;
469
470	/* Remove the MTD devices */
471	list_for_each_safe(pos, next, &blkmtd_device_list) {
472		struct block2mtd_dev *dev = list_entry(pos, typeof(*dev), list);
473		block2mtd_sync(&dev->mtd);
474		del_mtd_device(&dev->mtd);
475		INFO("mtd%d: [%s] removed", dev->mtd.index,
476				dev->mtd.name + strlen("blkmtd: "));
477		list_del(&dev->list);
478		block2mtd_free_device(dev);
479	}
480}
481
482
483module_init(block2mtd_init);
484module_exit(block2mtd_exit);
485
486MODULE_LICENSE("GPL");
487MODULE_AUTHOR("Simon Evans <spse@secret.org.uk> and others");
488MODULE_DESCRIPTION("Emulate an MTD using a block device");
489