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23#include <linux/fs.h>
24#include <linux/init.h>
25#include <linux/kernel.h>
26#include <linux/module.h>
27#include <linux/sched.h>
28#include <linux/slab.h>
29#include <linux/types.h>
30#include <linux/vmalloc.h>
31
32#include <linux/mtd/mtd.h>
33#include <linux/mtd/blktrans.h>
34#include <linux/mutex.h>
35#include <linux/major.h>
36
37
38struct mtdblk_dev {
39 struct mtd_blktrans_dev mbd;
40 int count;
41 struct mutex cache_mutex;
42 unsigned char *cache_data;
43 unsigned long cache_offset;
44 unsigned int cache_size;
45 enum { STATE_EMPTY, STATE_CLEAN, STATE_DIRTY } cache_state;
46};
47
48
49
50
51
52
53
54
55
56
57
58static int erase_write (struct mtd_info *mtd, unsigned long pos,
59 int len, const char *buf)
60{
61 struct erase_info erase;
62 size_t retlen;
63 int ret;
64
65
66
67
68 erase.addr = pos;
69 erase.len = len;
70
71 ret = mtd_erase(mtd, &erase);
72 if (ret) {
73 printk (KERN_WARNING "mtdblock: erase of region [0x%lx, 0x%x] "
74 "on \"%s\" failed\n",
75 pos, len, mtd->name);
76 return ret;
77 }
78
79
80
81
82
83 ret = mtd_write(mtd, pos, len, &retlen, buf);
84 if (ret)
85 return ret;
86 if (retlen != len)
87 return -EIO;
88 return 0;
89}
90
91
92static int write_cached_data (struct mtdblk_dev *mtdblk)
93{
94 struct mtd_info *mtd = mtdblk->mbd.mtd;
95 int ret;
96
97 if (mtdblk->cache_state != STATE_DIRTY)
98 return 0;
99
100 pr_debug("mtdblock: writing cached data for \"%s\" "
101 "at 0x%lx, size 0x%x\n", mtd->name,
102 mtdblk->cache_offset, mtdblk->cache_size);
103
104 ret = erase_write (mtd, mtdblk->cache_offset,
105 mtdblk->cache_size, mtdblk->cache_data);
106 if (ret)
107 return ret;
108
109
110
111
112
113
114
115
116 mtdblk->cache_state = STATE_EMPTY;
117 return 0;
118}
119
120
121static int do_cached_write (struct mtdblk_dev *mtdblk, unsigned long pos,
122 int len, const char *buf)
123{
124 struct mtd_info *mtd = mtdblk->mbd.mtd;
125 unsigned int sect_size = mtdblk->cache_size;
126 size_t retlen;
127 int ret;
128
129 pr_debug("mtdblock: write on \"%s\" at 0x%lx, size 0x%x\n",
130 mtd->name, pos, len);
131
132 if (!sect_size)
133 return mtd_write(mtd, pos, len, &retlen, buf);
134
135 while (len > 0) {
136 unsigned long sect_start = (pos/sect_size)*sect_size;
137 unsigned int offset = pos - sect_start;
138 unsigned int size = sect_size - offset;
139 if( size > len )
140 size = len;
141
142 if (size == sect_size) {
143
144
145
146
147
148 ret = erase_write (mtd, pos, size, buf);
149 if (ret)
150 return ret;
151 } else {
152
153
154 if (mtdblk->cache_state == STATE_DIRTY &&
155 mtdblk->cache_offset != sect_start) {
156 ret = write_cached_data(mtdblk);
157 if (ret)
158 return ret;
159 }
160
161 if (mtdblk->cache_state == STATE_EMPTY ||
162 mtdblk->cache_offset != sect_start) {
163
164 mtdblk->cache_state = STATE_EMPTY;
165 ret = mtd_read(mtd, sect_start, sect_size,
166 &retlen, mtdblk->cache_data);
167 if (ret)
168 return ret;
169 if (retlen != sect_size)
170 return -EIO;
171
172 mtdblk->cache_offset = sect_start;
173 mtdblk->cache_size = sect_size;
174 mtdblk->cache_state = STATE_CLEAN;
175 }
176
177
178 memcpy (mtdblk->cache_data + offset, buf, size);
179 mtdblk->cache_state = STATE_DIRTY;
180 }
181
182 buf += size;
183 pos += size;
184 len -= size;
185 }
186
187 return 0;
188}
189
190
191static int do_cached_read (struct mtdblk_dev *mtdblk, unsigned long pos,
192 int len, char *buf)
193{
194 struct mtd_info *mtd = mtdblk->mbd.mtd;
195 unsigned int sect_size = mtdblk->cache_size;
196 size_t retlen;
197 int ret;
198
199 pr_debug("mtdblock: read on \"%s\" at 0x%lx, size 0x%x\n",
200 mtd->name, pos, len);
201
202 if (!sect_size)
203 return mtd_read(mtd, pos, len, &retlen, buf);
204
205 while (len > 0) {
206 unsigned long sect_start = (pos/sect_size)*sect_size;
207 unsigned int offset = pos - sect_start;
208 unsigned int size = sect_size - offset;
209 if (size > len)
210 size = len;
211
212
213
214
215
216
217
218 if (mtdblk->cache_state != STATE_EMPTY &&
219 mtdblk->cache_offset == sect_start) {
220 memcpy (buf, mtdblk->cache_data + offset, size);
221 } else {
222 ret = mtd_read(mtd, pos, size, &retlen, buf);
223 if (ret)
224 return ret;
225 if (retlen != size)
226 return -EIO;
227 }
228
229 buf += size;
230 pos += size;
231 len -= size;
232 }
233
234 return 0;
235}
236
237static int mtdblock_readsect(struct mtd_blktrans_dev *dev,
238 unsigned long block, char *buf)
239{
240 struct mtdblk_dev *mtdblk = container_of(dev, struct mtdblk_dev, mbd);
241 return do_cached_read(mtdblk, block<<9, 512, buf);
242}
243
244static int mtdblock_writesect(struct mtd_blktrans_dev *dev,
245 unsigned long block, char *buf)
246{
247 struct mtdblk_dev *mtdblk = container_of(dev, struct mtdblk_dev, mbd);
248 if (unlikely(!mtdblk->cache_data && mtdblk->cache_size)) {
249 mtdblk->cache_data = vmalloc(mtdblk->mbd.mtd->erasesize);
250 if (!mtdblk->cache_data)
251 return -EINTR;
252
253
254
255
256 }
257 return do_cached_write(mtdblk, block<<9, 512, buf);
258}
259
260static int mtdblock_open(struct mtd_blktrans_dev *mbd)
261{
262 struct mtdblk_dev *mtdblk = container_of(mbd, struct mtdblk_dev, mbd);
263
264 pr_debug("mtdblock_open\n");
265
266 if (mtdblk->count) {
267 mtdblk->count++;
268 return 0;
269 }
270
271
272 mtdblk->count = 1;
273 mutex_init(&mtdblk->cache_mutex);
274 mtdblk->cache_state = STATE_EMPTY;
275 if (!(mbd->mtd->flags & MTD_NO_ERASE) && mbd->mtd->erasesize) {
276 mtdblk->cache_size = mbd->mtd->erasesize;
277 mtdblk->cache_data = NULL;
278 }
279
280 pr_debug("ok\n");
281
282 return 0;
283}
284
285static void mtdblock_release(struct mtd_blktrans_dev *mbd)
286{
287 struct mtdblk_dev *mtdblk = container_of(mbd, struct mtdblk_dev, mbd);
288
289 pr_debug("mtdblock_release\n");
290
291 mutex_lock(&mtdblk->cache_mutex);
292 write_cached_data(mtdblk);
293 mutex_unlock(&mtdblk->cache_mutex);
294
295 if (!--mtdblk->count) {
296
297
298
299
300 if (mbd->file_mode & FMODE_WRITE)
301 mtd_sync(mbd->mtd);
302 vfree(mtdblk->cache_data);
303 }
304
305 pr_debug("ok\n");
306}
307
308static int mtdblock_flush(struct mtd_blktrans_dev *dev)
309{
310 struct mtdblk_dev *mtdblk = container_of(dev, struct mtdblk_dev, mbd);
311
312 mutex_lock(&mtdblk->cache_mutex);
313 write_cached_data(mtdblk);
314 mutex_unlock(&mtdblk->cache_mutex);
315 mtd_sync(dev->mtd);
316 return 0;
317}
318
319static void mtdblock_add_mtd(struct mtd_blktrans_ops *tr, struct mtd_info *mtd)
320{
321 struct mtdblk_dev *dev = kzalloc(sizeof(*dev), GFP_KERNEL);
322
323 if (!dev)
324 return;
325
326 dev->mbd.mtd = mtd;
327 dev->mbd.devnum = mtd->index;
328
329 dev->mbd.size = mtd->size >> 9;
330 dev->mbd.tr = tr;
331
332 if (!(mtd->flags & MTD_WRITEABLE))
333 dev->mbd.readonly = 1;
334
335 if (add_mtd_blktrans_dev(&dev->mbd))
336 kfree(dev);
337}
338
339static void mtdblock_remove_dev(struct mtd_blktrans_dev *dev)
340{
341 del_mtd_blktrans_dev(dev);
342}
343
344static struct mtd_blktrans_ops mtdblock_tr = {
345 .name = "mtdblock",
346 .major = MTD_BLOCK_MAJOR,
347 .part_bits = 0,
348 .blksize = 512,
349 .open = mtdblock_open,
350 .flush = mtdblock_flush,
351 .release = mtdblock_release,
352 .readsect = mtdblock_readsect,
353 .writesect = mtdblock_writesect,
354 .add_mtd = mtdblock_add_mtd,
355 .remove_dev = mtdblock_remove_dev,
356 .owner = THIS_MODULE,
357};
358
359static int __init init_mtdblock(void)
360{
361 return register_mtd_blktrans(&mtdblock_tr);
362}
363
364static void __exit cleanup_mtdblock(void)
365{
366 deregister_mtd_blktrans(&mtdblock_tr);
367}
368
369module_init(init_mtdblock);
370module_exit(cleanup_mtdblock);
371
372
373MODULE_LICENSE("GPL");
374MODULE_AUTHOR("Nicolas Pitre <nico@fluxnic.net> et al.");
375MODULE_DESCRIPTION("Caching read/erase/writeback block device emulation access to MTD devices");
376