drivers/mtd/ubi/gluebi.c

   1 /*
   2  * Copyright (c) International Business Machines Corp., 2006
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License as published by
   6  * the Free Software Foundation; either version 2 of the License, or
   7  * (at your option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See
  12  * the GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, write to the Free Software
  16  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
  17  *
  18  * Author: Artem Bityutskiy (Битюцкий Артём), Joern Engel
  19  */
  20
  21 /*
  22  * This file includes implementation of fake MTD devices for each UBI volume.
  23  * This sounds strange, but it is in fact quite useful to make MTD-oriented
  24  * software (including all the legacy software) to work on top of UBI.
  25  *
  26  * Gluebi emulates MTD devices of "MTD_UBIVOLUME" type. Their minimal I/O unit
  27  * size (mtd->writesize) is equivalent to the UBI minimal I/O unit. The
  28  * eraseblock size is equivalent to the logical eraseblock size of the volume.
  29  */
  30
  31 #include <linux/math64.h>
  32 #include "ubi.h"
  33
  34 /**
  35  * gluebi_get_device - get MTD device reference.
  36  * @mtd: the MTD device description object
  37  *
  38  * This function is called every time the MTD device is being opened and
  39  * implements the MTD get_device() operation. Returns zero in case of success
  40  * and a negative error code in case of failure.
  41  */
  42 static int gluebi_get_device(struct mtd_info *mtd)
  43 {
  44         struct ubi_volume *vol;
  45
  46         vol = container_of(mtd, struct ubi_volume, gluebi_mtd);
  47
  48         /*
  49          * We do not introduce locks for gluebi reference count because the
  50          * get_device()/put_device() calls are already serialized at MTD.
  51          */
  52         if (vol->gluebi_refcount > 0) {
  53                 /*
  54                  * The MTD device is already referenced and this is just one
  55                  * more reference. MTD allows many users to open the same
  56                  * volume simultaneously and do not distinguish between
  57                  * readers/writers/exclusive openers as UBI does. So we do not
  58                  * open the UBI volume again - just increase the reference
  59                  * counter and return.
  60                  */
  61                 vol->gluebi_refcount += 1;
  62                 return 0;
  63         }
  64
  65         /*
  66          * This is the first reference to this UBI volume via the MTD device
  67          * interface. Open the corresponding volume in read-write mode.
  68          */
  69         vol->gluebi_desc = ubi_open_volume(vol->ubi->ubi_num, vol->vol_id,
  70                                            UBI_READWRITE);
  71         if (IS_ERR(vol->gluebi_desc))
  72                 return PTR_ERR(vol->gluebi_desc);
  73         vol->gluebi_refcount += 1;
  74         return 0;
  75 }
  76
  77 /**
  78  * gluebi_put_device - put MTD device reference.
  79  * @mtd: the MTD device description object
  80  *
  81  * This function is called every time the MTD device is being put. Returns
  82  * zero in case of success and a negative error code in case of failure.
  83  */
  84 static void gluebi_put_device(struct mtd_info *mtd)
  85 {
  86         struct ubi_volume *vol;
  87
  88         vol = container_of(mtd, struct ubi_volume, gluebi_mtd);
  89         vol->gluebi_refcount -= 1;
  90         ubi_assert(vol->gluebi_refcount >= 0);
  91         if (vol->gluebi_refcount == 0)
  92                 ubi_close_volume(vol->gluebi_desc);
  93 }
  94
  95 /**
  96  * gluebi_read - read operation of emulated MTD devices.
  97  * @mtd: MTD device description object
  98  * @from: absolute offset from where to read
  99  * @len: how many bytes to read
 100  * @retlen: count of read bytes is returned here
 101  * @buf: buffer to store the read data
 102  *
 103  * This function returns zero in case of success and a negative error code in
 104  * case of failure.
 105  */
 106 static int gluebi_read(struct mtd_info *mtd, loff_t from, size_t len,
 107                        size_t *retlen, unsigned char *buf)
 108 {
 109         int err = 0, lnum, offs, total_read;
 110         struct ubi_volume *vol;
 111         struct ubi_device *ubi;
 112
 113         dbg_gen("read %zd bytes from offset %lld", len, from);
 114
 115         if (len < 0 || from < 0 || from + len > mtd->size)
 116                 return -EINVAL;
 117
 118         vol = container_of(mtd, struct ubi_volume, gluebi_mtd);
 119         ubi = vol->ubi;
 120
 121         lnum = div_u64_rem(from, mtd->erasesize, &offs);
 122         total_read = len;
 123         while (total_read) {
 124                 size_t to_read = mtd->erasesize - offs;
 125
 126                 if (to_read > total_read)
 127                         to_read = total_read;
 128
 129                 err = ubi_eba_read_leb(ubi, vol, lnum, buf, offs, to_read, 0);
 130                 if (err)
 131                         break;
 132
 133                 lnum += 1;
 134                 offs = 0;
 135                 total_read -= to_read;
 136                 buf += to_read;
 137         }
 138
 139         *retlen = len - total_read;
 140         return err;
 141 }
 142
 143 /**
 144  * gluebi_write - write operation of emulated MTD devices.
 145  * @mtd: MTD device description object
 146  * @to: absolute offset where to write
 147  * @len: how many bytes to write
 148  * @retlen: count of written bytes is returned here
 149  * @buf: buffer with data to write
 150  *
 151  * This function returns zero in case of success and a negative error code in
 152  * case of failure.
 153  */
 154 static int gluebi_write(struct mtd_info *mtd, loff_t to, size_t len,
 155                        size_t *retlen, const u_char *buf)
 156 {
 157         int err = 0, lnum, offs, total_written;
 158         struct ubi_volume *vol;
 159         struct ubi_device *ubi;
 160
 161         dbg_gen("write %zd bytes to offset %lld", len, to);
 162
 163         if (len < 0 || to < 0 || len + to > mtd->size)
 164                 return -EINVAL;
 165
 166         vol = container_of(mtd, struct ubi_volume, gluebi_mtd);
 167         ubi = vol->ubi;
 168
 169         if (ubi->ro_mode)
 170                 return -EROFS;
 171
 172         lnum = div_u64_rem(to, mtd->erasesize, &offs);
 173
 174         if (len % mtd->writesize || offs % mtd->writesize)
 175                 return -EINVAL;
 176
 177         total_written = len;
 178         while (total_written) {
 179                 size_t to_write = mtd->erasesize - offs;
 180
 181                 if (to_write > total_written)
 182                         to_write = total_written;
 183
 184                 err = ubi_eba_write_leb(ubi, vol, lnum, buf, offs, to_write,
 185                                         UBI_UNKNOWN);
 186                 if (err)
 187                         break;
 188
 189                 lnum += 1;
 190                 offs = 0;
 191                 total_written -= to_write;
 192                 buf += to_write;
 193         }
 194
 195         *retlen = len - total_written;
 196         return err;
 197 }
 198
 199 /**
 200  * gluebi_erase - erase operation of emulated MTD devices.
 201  * @mtd: the MTD device description object
 202  * @instr: the erase operation description
 203  *
 204  * This function calls the erase callback when finishes. Returns zero in case
 205  * of success and a negative error code in case of failure.
 206  */
 207 static int gluebi_erase(struct mtd_info *mtd, struct erase_info *instr)
 208 {
 209         int err, i, lnum, count;
 210         struct ubi_volume *vol;
 211         struct ubi_device *ubi;
 212
 213         dbg_gen("erase %llu bytes at offset %llu", (unsigned long long)instr->len,
 214                  (unsigned long long)instr->addr);
 215
 216         if (instr->addr < 0 || instr->addr > mtd->size - mtd->erasesize)
 217                 return -EINVAL;
 218
 219         if (instr->len < 0 || instr->addr + instr->len > mtd->size)
 220                 return -EINVAL;
 221
 222         if (mtd_mod_by_ws(instr->addr, mtd) || mtd_mod_by_ws(instr->len, mtd))
 223                 return -EINVAL;
 224
 225         lnum = mtd_div_by_eb(instr->addr, mtd);
 226         count = mtd_div_by_eb(instr->len, mtd);
 227
 228         vol = container_of(mtd, struct ubi_volume, gluebi_mtd);
 229         ubi = vol->ubi;
 230
 231         if (ubi->ro_mode)
 232                 return -EROFS;
 233
 234         for (i = 0; i < count; i++) {
 235                 err = ubi_eba_unmap_leb(ubi, vol, lnum + i);
 236                 if (err)
 237                         goto out_err;
 238         }
 239
 240         /*
 241          * MTD erase operations are synchronous, so we have to make sure the
 242          * physical eraseblock is wiped out.
 243          */
 244         err = ubi_wl_flush(ubi);
 245         if (err)
 246                 goto out_err;
 247
 248         instr->state = MTD_ERASE_DONE;
 249         mtd_erase_callback(instr);
 250         return 0;
 251
 252 out_err:
 253         instr->state = MTD_ERASE_FAILED;
 254         instr->fail_addr = (long long)lnum * mtd->erasesize;
 255         return err;
 256 }
 257
 258 /**
 259  * ubi_create_gluebi - initialize gluebi for an UBI volume.
 260  * @ubi: UBI device description object
 261  * @vol: volume description object
 262  *
 263  * This function is called when an UBI volume is created in order to create
 264  * corresponding fake MTD device. Returns zero in case of success and a
 265  * negative error code in case of failure.
 266  */
 267 int ubi_create_gluebi(struct ubi_device *ubi, struct ubi_volume *vol)
 268 {
 269         struct mtd_info *mtd = &vol->gluebi_mtd;
 270
 271         mtd->name = kmemdup(vol->name, vol->name_len + 1, GFP_KERNEL);
 272         if (!mtd->name)
 273                 return -ENOMEM;
 274
 275         mtd->type = MTD_UBIVOLUME;
 276         if (!ubi->ro_mode)
 277                 mtd->flags = MTD_WRITEABLE;
 278         mtd->writesize  = ubi->min_io_size;
 279         mtd->owner      = THIS_MODULE;
 280         mtd->erasesize  = vol->usable_leb_size;
 281         mtd->read       = gluebi_read;
 282         mtd->write      = gluebi_write;
 283         mtd->erase      = gluebi_erase;
 284         mtd->get_device = gluebi_get_device;
 285         mtd->put_device = gluebi_put_device;
 286
 287         /*
 288          * In case of dynamic volume, MTD device size is just volume size. In
 289          * case of a static volume the size is equivalent to the amount of data
 290          * bytes.
 291          */
 292         if (vol->vol_type == UBI_DYNAMIC_VOLUME)
 293                 mtd->size = (long long)vol->usable_leb_size * vol->reserved_pebs;
 294         else
 295                 mtd->size = vol->used_bytes;
 296
 297         if (add_mtd_device(mtd)) {
 298                 ubi_err("cannot not add MTD device");
 299                 kfree(mtd->name);
 300                 return -ENFILE;
 301         }
 302
 303         dbg_gen("added mtd%d (\"%s\"), size %llu, EB size %u",
 304                 mtd->index, mtd->name, (unsigned long long)mtd->size, mtd->erasesize);
 305         return 0;
 306 }
 307
 308 /**
 309  * ubi_destroy_gluebi - close gluebi for an UBI volume.
 310  * @vol: volume description object
 311  *
 312  * This function is called when an UBI volume is removed in order to remove
 313  * corresponding fake MTD device. Returns zero in case of success and a
 314  * negative error code in case of failure.
 315  */
 316 int ubi_destroy_gluebi(struct ubi_volume *vol)
 317 {
 318         int err;
 319         struct mtd_info *mtd = &vol->gluebi_mtd;
 320
 321         dbg_gen("remove mtd%d", mtd->index);
 322         err = del_mtd_device(mtd);
 323         if (err)
 324                 return err;
 325         kfree(mtd->name);
 326         return 0;
 327 }
 328
 329 /**
 330  * ubi_gluebi_updated - UBI volume was updated notifier.
 331  * @vol: volume description object
 332  *
 333  * This function is called every time an UBI volume is updated. This function
 334  * does nothing if volume @vol is dynamic, and changes MTD device size if the
 335  * volume is static. This is needed because static volumes cannot be read past
 336  * data they contain.
 337  */
 338 void ubi_gluebi_updated(struct ubi_volume *vol)
 339 {
 340         struct mtd_info *mtd = &vol->gluebi_mtd;
 341
 342         if (vol->vol_type == UBI_STATIC_VOLUME)
 343                 mtd->size = vol->used_bytes;
 344 }