mtdcore.c revision 6ab3d5624e172c553004ecc862bfeac16d9d68b7 
1/*
2 * $Id: mtdcore.c,v 1.47 2005/11/07 11:14:20 gleixner Exp $
3 *
4 * Core registration and callback routines for MTD
5 * drivers and users.
6 *
7 */
8
9#include <linux/module.h>
10#include <linux/kernel.h>
11#include <linux/sched.h>
12#include <linux/ptrace.h>
13#include <linux/slab.h>
14#include <linux/string.h>
15#include <linux/timer.h>
16#include <linux/major.h>
17#include <linux/fs.h>
18#include <linux/ioctl.h>
19#include <linux/init.h>
20#include <linux/mtd/compatmac.h>
21#include <linux/proc_fs.h>
22
23#include <linux/mtd/mtd.h>
24
25/* These are exported solely for the purpose of mtd_blkdevs.c. You
26   should not use them for _anything_ else */
27DEFINE_MUTEX(mtd_table_mutex);
28struct mtd_info *mtd_table[MAX_MTD_DEVICES];
29
30EXPORT_SYMBOL_GPL(mtd_table_mutex);
31EXPORT_SYMBOL_GPL(mtd_table);
32
33static LIST_HEAD(mtd_notifiers);
34
35/**
36 *	add_mtd_device - register an MTD device
37 *	@mtd: pointer to new MTD device info structure
38 *
39 *	Add a device to the list of MTD devices present in the system, and
40 *	notify each currently active MTD 'user' of its arrival. Returns
41 *	zero on success or 1 on failure, which currently will only happen
42 *	if the number of present devices exceeds MAX_MTD_DEVICES (i.e. 16)
43 */
44
45int add_mtd_device(struct mtd_info *mtd)
46{
47	int i;
48
49	BUG_ON(mtd->writesize == 0);
50	mutex_lock(&mtd_table_mutex);
51
52	for (i=0; i < MAX_MTD_DEVICES; i++)
53		if (!mtd_table[i]) {
54			struct list_head *this;
55
56			mtd_table[i] = mtd;
57			mtd->index = i;
58			mtd->usecount = 0;
59
60			DEBUG(0, "mtd: Giving out device %d to %s\n",i, mtd->name);
61			/* No need to get a refcount on the module containing
62			   the notifier, since we hold the mtd_table_mutex */
63			list_for_each(this, &mtd_notifiers) {
64				struct mtd_notifier *not = list_entry(this, struct mtd_notifier, list);
65				not->add(mtd);
66			}
67
68			mutex_unlock(&mtd_table_mutex);
69			/* We _know_ we aren't being removed, because
70			   our caller is still holding us here. So none
71			   of this try_ nonsense, and no bitching about it
72			   either. :) */
73			__module_get(THIS_MODULE);
74			return 0;
75		}
76
77	mutex_unlock(&mtd_table_mutex);
78	return 1;
79}
80
81/**
82 *	del_mtd_device - unregister an MTD device
83 *	@mtd: pointer to MTD device info structure
84 *
85 *	Remove a device from the list of MTD devices present in the system,
86 *	and notify each currently active MTD 'user' of its departure.
87 *	Returns zero on success or 1 on failure, which currently will happen
88 *	if the requested device does not appear to be present in the list.
89 */
90
91int del_mtd_device (struct mtd_info *mtd)
92{
93	int ret;
94
95	mutex_lock(&mtd_table_mutex);
96
97	if (mtd_table[mtd->index] != mtd) {
98		ret = -ENODEV;
99	} else if (mtd->usecount) {
100		printk(KERN_NOTICE "Removing MTD device #%d (%s) with use count %d\n",
101		       mtd->index, mtd->name, mtd->usecount);
102		ret = -EBUSY;
103	} else {
104		struct list_head *this;
105
106		/* No need to get a refcount on the module containing
107		   the notifier, since we hold the mtd_table_mutex */
108		list_for_each(this, &mtd_notifiers) {
109			struct mtd_notifier *not = list_entry(this, struct mtd_notifier, list);
110			not->remove(mtd);
111		}
112
113		mtd_table[mtd->index] = NULL;
114
115		module_put(THIS_MODULE);
116		ret = 0;
117	}
118
119	mutex_unlock(&mtd_table_mutex);
120	return ret;
121}
122
123/**
124 *	register_mtd_user - register a 'user' of MTD devices.
125 *	@new: pointer to notifier info structure
126 *
127 *	Registers a pair of callbacks function to be called upon addition
128 *	or removal of MTD devices. Causes the 'add' callback to be immediately
129 *	invoked for each MTD device currently present in the system.
130 */
131
132void register_mtd_user (struct mtd_notifier *new)
133{
134	int i;
135
136	mutex_lock(&mtd_table_mutex);
137
138	list_add(&new->list, &mtd_notifiers);
139
140 	__module_get(THIS_MODULE);
141
142	for (i=0; i< MAX_MTD_DEVICES; i++)
143		if (mtd_table[i])
144			new->add(mtd_table[i]);
145
146	mutex_unlock(&mtd_table_mutex);
147}
148
149/**
150 *	unregister_mtd_user - unregister a 'user' of MTD devices.
151 *	@old: pointer to notifier info structure
152 *
153 *	Removes a callback function pair from the list of 'users' to be
154 *	notified upon addition or removal of MTD devices. Causes the
155 *	'remove' callback to be immediately invoked for each MTD device
156 *	currently present in the system.
157 */
158
159int unregister_mtd_user (struct mtd_notifier *old)
160{
161	int i;
162
163	mutex_lock(&mtd_table_mutex);
164
165	module_put(THIS_MODULE);
166
167	for (i=0; i< MAX_MTD_DEVICES; i++)
168		if (mtd_table[i])
169			old->remove(mtd_table[i]);
170
171	list_del(&old->list);
172	mutex_unlock(&mtd_table_mutex);
173	return 0;
174}
175
176
177/**
178 *	get_mtd_device - obtain a validated handle for an MTD device
179 *	@mtd: last known address of the required MTD device
180 *	@num: internal device number of the required MTD device
181 *
182 *	Given a number and NULL address, return the num'th entry in the device
183 *	table, if any.	Given an address and num == -1, search the device table
184 *	for a device with that address and return if it's still present. Given
185 *	both, return the num'th driver only if its address matches. Return NULL
186 *	if not.
187 */
188
189struct mtd_info *get_mtd_device(struct mtd_info *mtd, int num)
190{
191	struct mtd_info *ret = NULL;
192	int i;
193
194	mutex_lock(&mtd_table_mutex);
195
196	if (num == -1) {
197		for (i=0; i< MAX_MTD_DEVICES; i++)
198			if (mtd_table[i] == mtd)
199				ret = mtd_table[i];
200	} else if (num < MAX_MTD_DEVICES) {
201		ret = mtd_table[num];
202		if (mtd && mtd != ret)
203			ret = NULL;
204	}
205
206	if (ret && !try_module_get(ret->owner))
207		ret = NULL;
208
209	if (ret)
210		ret->usecount++;
211
212	mutex_unlock(&mtd_table_mutex);
213	return ret;
214}
215
216void put_mtd_device(struct mtd_info *mtd)
217{
218	int c;
219
220	mutex_lock(&mtd_table_mutex);
221	c = --mtd->usecount;
222	mutex_unlock(&mtd_table_mutex);
223	BUG_ON(c < 0);
224
225	module_put(mtd->owner);
226}
227
228/* default_mtd_writev - default mtd writev method for MTD devices that
229 *			dont implement their own
230 */
231
232int default_mtd_writev(struct mtd_info *mtd, const struct kvec *vecs,
233		       unsigned long count, loff_t to, size_t *retlen)
234{
235	unsigned long i;
236	size_t totlen = 0, thislen;
237	int ret = 0;
238
239	if(!mtd->write) {
240		ret = -EROFS;
241	} else {
242		for (i=0; i<count; i++) {
243			if (!vecs[i].iov_len)
244				continue;
245			ret = mtd->write(mtd, to, vecs[i].iov_len, &thislen, vecs[i].iov_base);
246			totlen += thislen;
247			if (ret || thislen != vecs[i].iov_len)
248				break;
249			to += vecs[i].iov_len;
250		}
251	}
252	if (retlen)
253		*retlen = totlen;
254	return ret;
255}
256
257EXPORT_SYMBOL(add_mtd_device);
258EXPORT_SYMBOL(del_mtd_device);
259EXPORT_SYMBOL(get_mtd_device);
260EXPORT_SYMBOL(put_mtd_device);
261EXPORT_SYMBOL(register_mtd_user);
262EXPORT_SYMBOL(unregister_mtd_user);
263EXPORT_SYMBOL(default_mtd_writev);
264
265#ifdef CONFIG_PROC_FS
266
267/*====================================================================*/
268/* Support for /proc/mtd */
269
270static struct proc_dir_entry *proc_mtd;
271
272static inline int mtd_proc_info (char *buf, int i)
273{
274	struct mtd_info *this = mtd_table[i];
275
276	if (!this)
277		return 0;
278
279	return sprintf(buf, "mtd%d: %8.8x %8.8x \"%s\"\n", i, this->size,
280		       this->erasesize, this->name);
281}
282
283static int mtd_read_proc (char *page, char **start, off_t off, int count,
284			  int *eof, void *data_unused)
285{
286	int len, l, i;
287        off_t   begin = 0;
288
289	mutex_lock(&mtd_table_mutex);
290
291	len = sprintf(page, "dev:    size   erasesize  name\n");
292        for (i=0; i< MAX_MTD_DEVICES; i++) {
293
294                l = mtd_proc_info(page + len, i);
295                len += l;
296                if (len+begin > off+count)
297                        goto done;
298                if (len+begin < off) {
299                        begin += len;
300                        len = 0;
301                }
302        }
303
304        *eof = 1;
305
306done:
307	mutex_unlock(&mtd_table_mutex);
308        if (off >= len+begin)
309                return 0;
310        *start = page + (off-begin);
311        return ((count < begin+len-off) ? count : begin+len-off);
312}
313
314/*====================================================================*/
315/* Init code */
316
317static int __init init_mtd(void)
318{
319	if ((proc_mtd = create_proc_entry( "mtd", 0, NULL )))
320		proc_mtd->read_proc = mtd_read_proc;
321	return 0;
322}
323
324static void __exit cleanup_mtd(void)
325{
326        if (proc_mtd)
327		remove_proc_entry( "mtd", NULL);
328}
329
330module_init(init_mtd);
331module_exit(cleanup_mtd);
332
333#endif /* CONFIG_PROC_FS */
334
335
336MODULE_LICENSE("GPL");
337MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>");
338MODULE_DESCRIPTION("Core MTD registration and access routines");
339