drivers/mtd/mtdblock.c

   1 /*
   2  * Direct MTD block device access
   3  *
   4  * $Id: mtdblock.c,v 1.64 2003/10/04 17:14:14 dwmw2 Exp $
   5  *
   6  * (C) 2000-2003 Nicolas Pitre <nico@cam.org>
   7  * (C) 1999-2003 David Woodhouse <dwmw2@infradead.org>
   8  * (C) 2002      David McCullough (Added MAGIC_ROM_PTR support)
   9  */
  10
  11 #include <linux/config.h>
  12 #include <linux/types.h>
  13 #include <linux/module.h>
  14 #include <linux/kernel.h>
  15 #include <linux/fs.h>
  16 #include <linux/init.h>
  17 #include <linux/slab.h>
  18 #include <linux/vmalloc.h>
  19 #include <linux/mtd/mtd.h>
  20 #include <linux/mtd/blktrans.h>
  21
  22 static struct mtdblk_dev {
  23         struct mtd_info *mtd;
  24         int count;
  25         struct semaphore cache_sem;
  26         unsigned char *cache_data;
  27         unsigned long cache_offset;
  28         unsigned int cache_size;
  29         enum { STATE_EMPTY, STATE_CLEAN, STATE_DIRTY } cache_state;
  30 } *mtdblks[MAX_MTD_DEVICES];
  31
  32 /*
  33  * Cache stuff...
  34  *
  35  * Since typical flash erasable sectors are much larger than what Linux's
  36  * buffer cache can handle, we must implement read-modify-write on flash
  37  * sectors for each block write requests.  To avoid over-erasing flash sectors
  38  * and to speed things up, we locally cache a whole flash sector while it is
  39  * being written to until a different sector is required.
  40  */
  41
  42 static void erase_callback(struct erase_info *done)
  43 {
  44         wait_queue_head_t *wait_q = (wait_queue_head_t *)done->priv;
  45         wake_up(wait_q);
  46 }
  47
  48 static int erase_write (struct mtd_info *mtd, unsigned long pos,
  49                         int len, const char *buf)
  50 {
  51         struct erase_info erase;
  52         DECLARE_WAITQUEUE(wait, current);
  53         wait_queue_head_t wait_q;
  54         size_t retlen;
  55         int ret;
  56
  57         /*
  58          * First, let's erase the flash block.
  59          */
  60
  61         init_waitqueue_head(&wait_q);
  62         erase.mtd = mtd;
  63         erase.callback = erase_callback;
  64         erase.addr = pos;
  65         erase.len = len;
  66         erase.priv = (u_long)&wait_q;
  67
  68 #if 1   // mask by Victor Yu. 05-14-2007
  69         set_current_state(TASK_INTERRUPTIBLE);
  70 #endif
  71         add_wait_queue(&wait_q, &wait);
  72
  73         ret = MTD_ERASE(mtd, &erase);
  74         if (ret) {
  75 #if 1   // mask by Victor Yu. 05-14-2007
  76                 set_current_state(TASK_RUNNING);
  77 #endif
  78                 remove_wait_queue(&wait_q, &wait);
  79                 printk (KERN_WARNING "mtdblock: erase of region [0x%lx, 0x%x] "
  80                                      "on \"%s\" failed\n",
  81                         pos, len, mtd->name);
  82                 return ret;
  83         }
  84
  85         schedule();  /* Wait for erase to finish. */
  86         remove_wait_queue(&wait_q, &wait);
  87
  88         /*
  89          * Next, writhe data to flash.
  90          */
  91
  92         ret = MTD_WRITE (mtd, pos, len, &retlen, buf);
  93         if (ret)
  94                 return ret;
  95         if (retlen != len)
  96                 return -EIO;
  97         return 0;
  98 }
  99
 100
 101 static int write_cached_data (struct mtdblk_dev *mtdblk)
 102 {
 103         struct mtd_info *mtd = mtdblk->mtd;
 104         int ret;
 105
 106         if (mtdblk->cache_state != STATE_DIRTY)
 107                 return 0;
 108
 109         DEBUG(MTD_DEBUG_LEVEL2, "mtdblock: writing cached data for \"%s\" "
 110                         "at 0x%lx, size 0x%x\n", mtd->name,
 111                         mtdblk->cache_offset, mtdblk->cache_size);
 112
 113         ret = erase_write (mtd, mtdblk->cache_offset,
 114                            mtdblk->cache_size, mtdblk->cache_data);
 115         if (ret)
 116                 return ret;
 117
 118         /*
 119          * Here we could argubly set the cache state to STATE_CLEAN.
 120          * However this could lead to inconsistency since we will not
 121          * be notified if this content is altered on the flash by other
 122          * means.  Let's declare it empty and leave buffering tasks to
 123          * the buffer cache instead.
 124          */
 125         mtdblk->cache_state = STATE_EMPTY;
 126         return 0;
 127 }
 128
 129
 130 static int do_cached_write (struct mtdblk_dev *mtdblk, unsigned long pos,
 131                             int len, const char *buf)
 132 {
 133         struct mtd_info *mtd = mtdblk->mtd;
 134         unsigned int sect_size = mtdblk->cache_size;
 135         size_t retlen;
 136         int ret;
 137
 138         DEBUG(MTD_DEBUG_LEVEL2, "mtdblock: write on \"%s\" at 0x%lx, size 0x%x\n",
 139                 mtd->name, pos, len);
 140
 141         if (!sect_size)
 142                 return MTD_WRITE (mtd, pos, len, &retlen, buf);
 143
 144         while (len > 0) {
 145                 unsigned long sect_start = (pos/sect_size)*sect_size;
 146                 unsigned int offset = pos - sect_start;
 147                 unsigned int size = sect_size - offset;
 148                 if( size > len )
 149                         size = len;
 150
 151                 if (size == sect_size) {
 152                         /*
 153                          * We are covering a whole sector.  Thus there is no
 154                          * need to bother with the cache while it may still be
 155                          * useful for other partial writes.
 156                          */
 157                         ret = erase_write (mtd, pos, size, buf);
 158                         if (ret)
 159                                 return ret;
 160                 } else {
 161                         /* Partial sector: need to use the cache */
 162
 163                         if (mtdblk->cache_state == STATE_DIRTY &&
 164                             mtdblk->cache_offset != sect_start) {
 165                                 ret = write_cached_data(mtdblk);
 166                                 if (ret)
 167                                         return ret;
 168                         }
 169
 170                         if (mtdblk->cache_state == STATE_EMPTY ||
 171                             mtdblk->cache_offset != sect_start) {
 172                                 /* fill the cache with the current sector */
 173                                 mtdblk->cache_state = STATE_EMPTY;
 174                                 ret = MTD_READ(mtd, sect_start, sect_size, &retlen, mtdblk->cache_data);
 175                                 if (ret)
 176                                         return ret;
 177                                 if (retlen != sect_size)
 178                                         return -EIO;
 179
 180                                 mtdblk->cache_offset = sect_start;
 181                                 mtdblk->cache_size = sect_size;
 182                                 mtdblk->cache_state = STATE_CLEAN;
 183                         }
 184
 185                         /* write data to our local cache */
 186                         memcpy (mtdblk->cache_data + offset, buf, size);
 187                         mtdblk->cache_state = STATE_DIRTY;
 188                 }
 189
 190                 buf += size;
 191                 pos += size;
 192                 len -= size;
 193         }
 194
 195         return 0;
 196 }
 197
 198
 199 static int do_cached_read (struct mtdblk_dev *mtdblk, unsigned long pos,
 200                            int len, char *buf)
 201 {
 202         struct mtd_info *mtd = mtdblk->mtd;
 203         unsigned int sect_size = mtdblk->cache_size;
 204         size_t retlen;
 205         int ret;
 206
 207         DEBUG(MTD_DEBUG_LEVEL2, "mtdblock: read on \"%s\" at 0x%lx, size 0x%x\n",
 208                         mtd->name, pos, len);
 209
 210         if (!sect_size)
 211                 return MTD_READ (mtd, pos, len, &retlen, buf);
 212
 213         while (len > 0) {
 214                 unsigned long sect_start = (pos/sect_size)*sect_size;
 215                 unsigned int offset = pos - sect_start;
 216                 unsigned int size = sect_size - offset;
 217                 if (size > len)
 218                         size = len;
 219
 220                 /*
 221                  * Check if the requested data is already cached
 222                  * Read the requested amount of data from our internal cache if it
 223                  * contains what we want, otherwise we read the data directly
 224                  * from flash.
 225                  */
 226                 if (mtdblk->cache_state != STATE_EMPTY &&
 227                     mtdblk->cache_offset == sect_start) {
 228                         memcpy (buf, mtdblk->cache_data + offset, size);
 229                 } else {
 230                         ret = MTD_READ (mtd, pos, size, &retlen, buf);
 231                         if (ret)
 232                                 return ret;
 233                         if (retlen != size)
 234                                 return -EIO;
 235                 }
 236
 237                 buf += size;
 238                 pos += size;
 239                 len -= size;
 240         }
 241
 242         return 0;
 243 }
 244
 245 static int mtdblock_readsect(struct mtd_blktrans_dev *dev,
 246                               unsigned long block, char *buf)
 247 {
 248         struct mtdblk_dev *mtdblk = mtdblks[dev->devnum];
 249         return do_cached_read(mtdblk, block<<9, 512, buf);
 250 }
 251
 252 static int mtdblock_writesect(struct mtd_blktrans_dev *dev,
 253                               unsigned long block, char *buf)
 254 {
 255         struct mtdblk_dev *mtdblk = mtdblks[dev->devnum];
 256         if (unlikely(!mtdblk->cache_data)) {
 257                 mtdblk->cache_data = vmalloc(mtdblk->mtd->erasesize);
 258                 if (!mtdblk->cache_data)
 259                         return -EINTR;
 260                 /* -EINTR is not really correct, but it is the best match
 261                  * documented in man 2 write for all cases.  We could also
 262                  * return -EAGAIN sometimes, but why bother?
 263                  */
 264         }
 265         return do_cached_write(mtdblk, block<<9, 512, buf);
 266 }
 267
 268 static int mtdblock_open(struct mtd_blktrans_dev *mbd)
 269 {
 270         struct mtdblk_dev *mtdblk;
 271         struct mtd_info *mtd = mbd->mtd;
 272         int dev = mbd->devnum;
 273
 274         DEBUG(MTD_DEBUG_LEVEL1,"mtdblock_open\n");
 275
 276         if (mtdblks[dev]) {
 277                 mtdblks[dev]->count++;
 278                 return 0;
 279         }
 280
 281         /* OK, it's not open. Create cache info for it */
 282         mtdblk = kmalloc(sizeof(struct mtdblk_dev), GFP_KERNEL);
 283         if (!mtdblk)
 284                 return -ENOMEM;
 285
 286         memset(mtdblk, 0, sizeof(*mtdblk));
 287         mtdblk->count = 1;
 288         mtdblk->mtd = mtd;
 289
 290         init_MUTEX (&mtdblk->cache_sem);
 291         mtdblk->cache_state = STATE_EMPTY;
 292         if ((mtdblk->mtd->flags & MTD_CAP_RAM) != MTD_CAP_RAM &&
 293             mtdblk->mtd->erasesize) {
 294                 mtdblk->cache_size = mtdblk->mtd->erasesize;
 295                 mtdblk->cache_data = NULL;
 296         }
 297
 298         mtdblks[dev] = mtdblk;
 299
 300         DEBUG(MTD_DEBUG_LEVEL1, "ok\n");
 301
 302         return 0;
 303 }
 304
 305 static int mtdblock_release(struct mtd_blktrans_dev *mbd)
 306 {
 307         int dev = mbd->devnum;
 308         struct mtdblk_dev *mtdblk = mtdblks[dev];
 309
 310         DEBUG(MTD_DEBUG_LEVEL1, "mtdblock_release\n");
 311
 312         down(&mtdblk->cache_sem);
 313         write_cached_data(mtdblk);
 314         up(&mtdblk->cache_sem);
 315
 316         if (!--mtdblk->count) {
 317                 /* It was the last usage. Free the device */
 318                 mtdblks[dev] = NULL;
 319                 if (mtdblk->mtd->sync)
 320                         mtdblk->mtd->sync(mtdblk->mtd);
 321                 vfree(mtdblk->cache_data);
 322                 kfree(mtdblk);
 323         }
 324         DEBUG(MTD_DEBUG_LEVEL1, "ok\n");
 325
 326         return 0;
 327 }
 328
 329 static int mtdblock_flush(struct mtd_blktrans_dev *dev)
 330 {
 331         struct mtdblk_dev *mtdblk = mtdblks[dev->devnum];
 332
 333         down(&mtdblk->cache_sem);
 334         write_cached_data(mtdblk);
 335         up(&mtdblk->cache_sem);
 336
 337         if (mtdblk->mtd->sync)
 338                 mtdblk->mtd->sync(mtdblk->mtd);
 339         return 0;
 340 }
 341
 342 #ifdef CONFIG_MAGIC_ROM_PTR
 343 #include <linux/mm.h>
 344 static int
 345 mtdblock_romptr(struct mtd_blktrans_dev *dev, struct vm_area_struct * vma)
 346 {
 347         struct mtd_info *mtd = dev->mtd;
 348         u_char *ptr;
 349         size_t len;
 350
 351         if (!mtd->point /* Can't do it, No function to point to correct addr */
 352
 353         || (*mtd->point)(mtd,vma->vm_pgoff,vma->vm_end-vma->vm_start,&len,&ptr) != 0)
 354                 return -ENOSYS;
 355
 356         vma->vm_start = (unsigned long) ptr;
 357         vma->vm_end = vma->vm_start + len;
 358         return 0;
 359 }
 360 #endif
 361
 362 static void mtdblock_add_mtd(struct mtd_blktrans_ops *tr, struct mtd_info *mtd)
 363 {
 364         struct mtd_blktrans_dev *dev = kmalloc(sizeof(*dev), GFP_KERNEL);
 365
 366         if (!dev)
 367                 return;
 368
 369         memset(dev, 0, sizeof(*dev));
 370
 371         dev->mtd = mtd;
 372         dev->devnum = mtd->index;
 373         dev->blksize = 512;
 374         dev->size = mtd->size >> 9;
 375         dev->tr = tr;
 376
 377         if (!(mtd->flags & MTD_WRITEABLE))
 378                 dev->readonly = 1;
 379
 380         add_mtd_blktrans_dev(dev);
 381 }
 382
 383 static void mtdblock_remove_dev(struct mtd_blktrans_dev *dev)
 384 {
 385         del_mtd_blktrans_dev(dev);
 386         kfree(dev);
 387 }
 388
 389 struct mtd_blktrans_ops mtdblock_tr = {
 390         .name           = "mtdblock",
 391         .major          = 31,
 392         .part_bits      = 0,
 393         .open           = mtdblock_open,
 394         .flush          = mtdblock_flush,
 395         .release        = mtdblock_release,
 396         .readsect       = mtdblock_readsect,
 397         .writesect      = mtdblock_writesect,
 398         .add_mtd        = mtdblock_add_mtd,
 399         .remove_dev     = mtdblock_remove_dev,
 400         .owner          = THIS_MODULE,
 401 #ifdef CONFIG_MAGIC_ROM_PTR
 402         .romptr         = mtdblock_romptr,
 403 #endif
 404 };
 405
 406 int __init init_mtdblock(void)
 407 {
 408         return register_mtd_blktrans(&mtdblock_tr);
 409 }
 410
 411 static void __exit cleanup_mtdblock(void)
 412 {
 413         deregister_mtd_blktrans(&mtdblock_tr);
 414 }
 415
 416 module_init(init_mtdblock);
 417 module_exit(cleanup_mtdblock);
 418
 419
 420 MODULE_LICENSE("GPL");
 421 MODULE_AUTHOR("Nicolas Pitre <nico@cam.org> et al.");
 422 MODULE_DESCRIPTION("Caching read/erase/writeback block device emulation access to MTD devices");