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 <asm/div64.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         uint64_t tmp = from;
 113
 114         dbg_gen("read %zd bytes from offset %lld", len, from);
 115
 116         if (len < 0 || from < 0 || from + len > mtd->size)
 117                 return -EINVAL;
 118
 119         vol = container_of(mtd, struct ubi_volume, gluebi_mtd);
 120         ubi = vol->ubi;
 121
 122         offs = do_div(tmp, mtd->erasesize);
 123         lnum = tmp;
 124
 125         total_read = len;
 126         while (total_read) {
 127                 size_t to_read = mtd->erasesize - offs;
 128
 129                 if (to_read > total_read)
 130                         to_read = total_read;
 131
 132                 err = ubi_eba_read_leb(ubi, vol, lnum, buf, offs, to_read, 0);
 133                 if (err)
 134                         break;
 135
 136                 lnum += 1;
 137                 offs = 0;
 138                 total_read -= to_read;
 139                 buf += to_read;
 140         }
 141
 142         *retlen = len - total_read;
 143         return err;
 144 }
 145
 146 /**
 147  * gluebi_write - write operation of emulated MTD devices.
 148  * @mtd: MTD device description object
 149  * @to: absolute offset where to write
 150  * @len: how many bytes to write
 151  * @retlen: count of written bytes is returned here
 152  * @buf: buffer with data to write
 153  *
 154  * This function returns zero in case of success and a negative error code in
 155  * case of failure.
 156  */
 157 static int gluebi_write(struct mtd_info *mtd, loff_t to, size_t len,
 158                        size_t *retlen, const u_char *buf)
 159 {
 160         int err = 0, lnum, offs, total_written;
 161         struct ubi_volume *vol;
 162         struct ubi_device *ubi;
 163         uint64_t tmp = to;
 164
 165         dbg_gen("write %zd bytes to offset %lld", len, to);
 166
 167         if (len < 0 || to < 0 || len + to > mtd->size)
 168                 return -EINVAL;
 169
 170         vol = container_of(mtd, struct ubi_volume, gluebi_mtd);
 171         ubi = vol->ubi;
 172
 173         if (ubi->ro_mode)
 174                 return -EROFS;
 175
 176         offs = do_div(tmp, mtd->erasesize);
 177         lnum = tmp;
 178
 179         if (len % mtd->writesize || offs % mtd->writesize)
 180                 return -EINVAL;
 181
 182         total_written = len;
 183         while (total_written) {
 184                 size_t to_write = mtd->erasesize - offs;
 185
 186                 if (to_write > total_written)
 187                         to_write = total_written;
 188
 189                 err = ubi_eba_write_leb(ubi, vol, lnum, buf, offs, to_write,
 190                                         UBI_UNKNOWN);
 191                 if (err)
 192                         break;
 193
 194                 lnum += 1;
 195                 offs = 0;
 196                 total_written -= to_write;
 197                 buf += to_write;
 198         }
 199
 200         *retlen = len - total_written;
 201         return err;
 202 }
 203
 204 /**
 205  * gluebi_erase - erase operation of emulated MTD devices.
 206  * @mtd: the MTD device description object
 207  * @instr: the erase operation description
 208  *
 209  * This function calls the erase callback when finishes. Returns zero in case
 210  * of success and a negative error code in case of failure.
 211  */
 212 static int gluebi_erase(struct mtd_info *mtd, struct erase_info *instr)
 213 {
 214         int err, i, lnum, count;
 215         struct ubi_volume *vol;
 216         struct ubi_device *ubi;
 217
 218         dbg_gen("erase %u bytes at offset %u", instr->len, instr->addr);
 219
 220         if (instr->addr < 0 || instr->addr > mtd->size - mtd->erasesize)
 221                 return -EINVAL;
 222
 223         if (instr->len < 0 || instr->addr + instr->len > mtd->size)
 224                 return -EINVAL;
 225
 226         if (instr->addr % mtd->writesize || instr->len % mtd->writesize)
 227                 return -EINVAL;
 228
 229         lnum = instr->addr / mtd->erasesize;
 230         count = instr->len / mtd->erasesize;
 231
 232         vol = container_of(mtd, struct ubi_volume, gluebi_mtd);
 233         ubi = vol->ubi;
 234
 235         if (ubi->ro_mode)
 236                 return -EROFS;
 237
 238         for (i = 0; i < count; i++) {
 239                 err = ubi_eba_unmap_leb(ubi, vol, lnum + i);
 240                 if (err)
 241                         goto out_err;
 242         }
 243
 244         /*
 245          * MTD erase operations are synchronous, so we have to make sure the
 246          * physical eraseblock is wiped out.
 247          */
 248         err = ubi_wl_flush(ubi);
 249         if (err)
 250                 goto out_err;
 251
 252         instr->state = MTD_ERASE_DONE;
 253         mtd_erase_callback(instr);
 254         return 0;
 255
 256 out_err:
 257         instr->state = MTD_ERASE_FAILED;
 258         instr->fail_addr = lnum * mtd->erasesize;
 259         return err;
 260 }
 261
 262 /**
 263  * ubi_create_gluebi - initialize gluebi for an UBI volume.
 264  * @ubi: UBI device description object
 265  * @vol: volume description object
 266  *
 267  * This function is called when an UBI volume is created in order to create
 268  * corresponding fake MTD device. Returns zero in case of success and a
 269  * negative error code in case of failure.
 270  */
 271 int ubi_create_gluebi(struct ubi_device *ubi, struct ubi_volume *vol)
 272 {
 273         struct mtd_info *mtd = &vol->gluebi_mtd;
 274
 275         mtd->name = kmemdup(vol->name, vol->name_len + 1, GFP_KERNEL);
 276         if (!mtd->name)
 277                 return -ENOMEM;
 278
 279         mtd->type = MTD_UBIVOLUME;
 280         if (!ubi->ro_mode)
 281                 mtd->flags = MTD_WRITEABLE;
 282         mtd->writesize  = ubi->min_io_size;
 283         mtd->owner      = THIS_MODULE;
 284         mtd->erasesize  = vol->usable_leb_size;
 285         mtd->read       = gluebi_read;
 286         mtd->write      = gluebi_write;
 287         mtd->erase      = gluebi_erase;
 288         mtd->get_device = gluebi_get_device;
 289         mtd->put_device = gluebi_put_device;
 290
 291         /*
 292          * In case of dynamic volume, MTD device size is just volume size. In
 293          * case of a static volume the size is equivalent to the amount of data
 294          * bytes.
 295          */
 296         if (vol->vol_type == UBI_DYNAMIC_VOLUME)
 297                 mtd->size = vol->usable_leb_size * vol->reserved_pebs;
 298         else
 299                 mtd->size = vol->used_bytes;
 300
 301         if (add_mtd_device(mtd)) {
 302                 ubi_err("cannot not add MTD device");
 303                 kfree(mtd->name);
 304                 return -ENFILE;
 305         }
 306
 307         dbg_gen("added mtd%d (\"%s\"), size %u, EB size %u",
 308                 mtd->index, mtd->name, mtd->size, mtd->erasesize);
 309         return 0;
 310 }
 311
 312 /**
 313  * ubi_destroy_gluebi - close gluebi for an UBI volume.
 314  * @vol: volume description object
 315  *
 316  * This function is called when an UBI volume is removed in order to remove
 317  * corresponding fake MTD device. Returns zero in case of success and a
 318  * negative error code in case of failure.
 319  */
 320 int ubi_destroy_gluebi(struct ubi_volume *vol)
 321 {
 322         int err;
 323         struct mtd_info *mtd = &vol->gluebi_mtd;
 324
 325         dbg_gen("remove mtd%d", mtd->index);
 326         err = del_mtd_device(mtd);
 327         if (err)
 328                 return err;
 329         kfree(mtd->name);
 330         return 0;
 331 }
 332
 333 /**
 334  * ubi_gluebi_updated - UBI volume was updated notifier.
 335  * @vol: volume description object
 336  *
 337  * This function is called every time an UBI volume is updated. This function
 338  * does nothing if volume @vol is dynamic, and changes MTD device size if the
 339  * volume is static. This is needed because static volumes cannot be read past
 340  * data they contain.
 341  */
 342 void ubi_gluebi_updated(struct ubi_volume *vol)
 343 {
 344         struct mtd_info *mtd = &vol->gluebi_mtd;
 345
 346         if (vol->vol_type == UBI_STATIC_VOLUME)
 347                 mtd->size = vol->used_bytes;
 348 }