drivers/mtd/parsers/cmdlinepart.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * Read flash partition table from command line
   4  *
   5  * Copyright © 2002      SYSGO Real-Time Solutions GmbH
   6  * Copyright © 2002-2010 David Woodhouse <dwmw2@infradead.org>
   7  *
   8  * The format for the command line is as follows:
   9  *
  10  * mtdparts=<mtddef>[;<mtddef]
  11  * <mtddef>  := <mtd-id>:<partdef>[,<partdef>]
  12  * <partdef> := <size>[@<offset>][<name>][ro][lk]
  13  * <mtd-id>  := unique name used in mapping driver/device (mtd->name)
  14  * <size>    := standard linux memsize OR "-" to denote all remaining space
  15  *              size is automatically truncated at end of device
  16  *              if specified or truncated size is 0 the part is skipped
  17  * <offset>  := standard linux memsize
  18  *              if omitted the part will immediately follow the previous part
  19  *              or 0 if the first part
  20  * <name>    := '(' NAME ')'
  21  *              NAME will appear in /proc/mtd
  22  *
  23  * <size> and <offset> can be specified such that the parts are out of order
  24  * in physical memory and may even overlap.
  25  *
  26  * The parts are assigned MTD numbers in the order they are specified in the
  27  * command line regardless of their order in physical memory.
  28  *
  29  * Examples:
  30  *
  31  * 1 NOR Flash, with 1 single writable partition:
  32  * edb7312-nor:-
  33  *
  34  * 1 NOR Flash with 2 partitions, 1 NAND with one
  35  * edb7312-nor:256k(ARMboot)ro,-(root);edb7312-nand:-(home)
  36  */
  37
  38 #define pr_fmt(fmt)     "mtd: " fmt
  39
  40 #include <linux/kernel.h>
  41 #include <linux/slab.h>
  42 #include <linux/mtd/mtd.h>
  43 #include <linux/mtd/partitions.h>
  44 #include <linux/module.h>
  45 #include <linux/err.h>
  46
  47 /* debug macro */
  48 #if 0
  49 #define dbg(x) do { printk("DEBUG-CMDLINE-PART: "); printk x; } while(0)
  50 #else
  51 #define dbg(x)
  52 #endif
  53
  54
  55 /* special size referring to all the remaining space in a partition */
  56 #define SIZE_REMAINING ULLONG_MAX
  57 #define OFFSET_CONTINUOUS ULLONG_MAX
  58
  59 struct cmdline_mtd_partition {
  60         struct cmdline_mtd_partition *next;
  61         char *mtd_id;
  62         int num_parts;
  63         struct mtd_partition *parts;
  64 };
  65
  66 /* mtdpart_setup() parses into here */
  67 static struct cmdline_mtd_partition *partitions;
  68
  69 /* the command line passed to mtdpart_setup() */
  70 static char *mtdparts;
  71 static char *cmdline;
  72 static int cmdline_parsed;
  73
  74 /*
  75  * Parse one partition definition for an MTD. Since there can be many
  76  * comma separated partition definitions, this function calls itself
  77  * recursively until no more partition definitions are found. Nice side
  78  * effect: the memory to keep the mtd_partition structs and the names
  79  * is allocated upon the last definition being found. At that point the
  80  * syntax has been verified ok.
  81  */
  82 static struct mtd_partition * newpart(char *s,
  83                                       char **retptr,
  84                                       int *num_parts,
  85                                       int this_part,
  86                                       unsigned char **extra_mem_ptr,
  87                                       int extra_mem_size)
  88 {
  89         struct mtd_partition *parts;
  90         unsigned long long size, offset = OFFSET_CONTINUOUS;
  91         char *name;
  92         int name_len;
  93         unsigned char *extra_mem;
  94         char delim;
  95         unsigned int mask_flags;
  96
  97         /* fetch the partition size */
  98         if (*s == '-') {
  99                 /* assign all remaining space to this partition */
 100                 size = SIZE_REMAINING;
 101                 s++;
 102         } else {
 103                 size = memparse(s, &s);
 104                 if (!size) {
 105                         pr_err("partition has size 0\n");
 106                         return ERR_PTR(-EINVAL);
 107                 }
 108         }
 109
 110         /* fetch partition name and flags */
 111         mask_flags = 0; /* this is going to be a regular partition */
 112         delim = 0;
 113
 114         /* check for offset */
 115         if (*s == '@') {
 116                 s++;
 117                 offset = memparse(s, &s);
 118         }
 119
 120         /* now look for name */
 121         if (*s == '(')
 122                 delim = ')';
 123
 124         if (delim) {
 125                 char *p;
 126
 127                 name = ++s;
 128                 p = strchr(name, delim);
 129                 if (!p) {
 130                         pr_err("no closing %c found in partition name\n", delim);
 131                         return ERR_PTR(-EINVAL);
 132                 }
 133                 name_len = p - name;
 134                 s = p + 1;
 135         } else {
 136                 name = NULL;
 137                 name_len = 13; /* Partition_000 */
 138         }
 139
 140         /* record name length for memory allocation later */
 141         extra_mem_size += name_len + 1;
 142
 143         /* test for options */
 144         if (strncmp(s, "ro", 2) == 0) {
 145                 mask_flags |= MTD_WRITEABLE;
 146                 s += 2;
 147         }
 148
 149         /* if lk is found do NOT unlock the MTD partition*/
 150         if (strncmp(s, "lk", 2) == 0) {
 151                 mask_flags |= MTD_POWERUP_LOCK;
 152                 s += 2;
 153         }
 154
 155         /* test if more partitions are following */
 156         if (*s == ',') {
 157                 if (size == SIZE_REMAINING) {
 158                         pr_err("no partitions allowed after a fill-up partition\n");
 159                         return ERR_PTR(-EINVAL);
 160                 }
 161                 /* more partitions follow, parse them */
 162                 parts = newpart(s + 1, &s, num_parts, this_part + 1,
 163                                 &extra_mem, extra_mem_size);
 164                 if (IS_ERR(parts))
 165                         return parts;
 166         } else {
 167                 /* this is the last partition: allocate space for all */
 168                 int alloc_size;
 169
 170                 *num_parts = this_part + 1;
 171                 alloc_size = *num_parts * sizeof(struct mtd_partition) +
 172                              extra_mem_size;
 173
 174                 parts = kzalloc(alloc_size, GFP_KERNEL);
 175                 if (!parts)
 176                         return ERR_PTR(-ENOMEM);
 177                 extra_mem = (unsigned char *)(parts + *num_parts);
 178         }
 179
 180         /*
 181          * enter this partition (offset will be calculated later if it is
 182          * OFFSET_CONTINUOUS at this point)
 183          */
 184         parts[this_part].size = size;
 185         parts[this_part].offset = offset;
 186         parts[this_part].mask_flags = mask_flags;
 187         if (name)
 188                 strlcpy(extra_mem, name, name_len + 1);
 189         else
 190                 sprintf(extra_mem, "Partition_%03d", this_part);
 191         parts[this_part].name = extra_mem;
 192         extra_mem += name_len + 1;
 193
 194         dbg(("partition %d: name <%s>, offset %llx, size %llx, mask flags %x\n",
 195              this_part, parts[this_part].name, parts[this_part].offset,
 196              parts[this_part].size, parts[this_part].mask_flags));
 197
 198         /* return (updated) pointer to extra_mem memory */
 199         if (extra_mem_ptr)
 200                 *extra_mem_ptr = extra_mem;
 201
 202         /* return (updated) pointer command line string */
 203         *retptr = s;
 204
 205         /* return partition table */
 206         return parts;
 207 }
 208
 209 /*
 210  * Parse the command line.
 211  */
 212 static int mtdpart_setup_real(char *s)
 213 {
 214         cmdline_parsed = 1;
 215
 216         for( ; s != NULL; )
 217         {
 218                 struct cmdline_mtd_partition *this_mtd;
 219                 struct mtd_partition *parts;
 220                 int mtd_id_len, num_parts;
 221                 char *p, *mtd_id;
 222
 223                 mtd_id = s;
 224
 225                 /* fetch <mtd-id> */
 226                 p = strchr(s, ':');
 227                 if (!p) {
 228                         pr_err("no mtd-id\n");
 229                         return -EINVAL;
 230                 }
 231                 mtd_id_len = p - mtd_id;
 232
 233                 dbg(("parsing <%s>\n", p+1));
 234
 235                 /*
 236                  * parse one mtd. have it reserve memory for the
 237                  * struct cmdline_mtd_partition and the mtd-id string.
 238                  */
 239                 parts = newpart(p + 1,          /* cmdline */
 240                                 &s,             /* out: updated cmdline ptr */
 241                                 &num_parts,     /* out: number of parts */
 242                                 0,              /* first partition */
 243                                 (unsigned char**)&this_mtd, /* out: extra mem */
 244                                 mtd_id_len + 1 + sizeof(*this_mtd) +
 245                                 sizeof(void*)-1 /*alignment*/);
 246                 if (IS_ERR(parts)) {
 247                         /*
 248                          * An error occurred. We're either:
 249                          * a) out of memory, or
 250                          * b) in the middle of the partition spec
 251                          * Either way, this mtd is hosed and we're
 252                          * unlikely to succeed in parsing any more
 253                          */
 254                          return PTR_ERR(parts);
 255                  }
 256
 257                 /* align this_mtd */
 258                 this_mtd = (struct cmdline_mtd_partition *)
 259                                 ALIGN((unsigned long)this_mtd, sizeof(void *));
 260                 /* enter results */
 261                 this_mtd->parts = parts;
 262                 this_mtd->num_parts = num_parts;
 263                 this_mtd->mtd_id = (char*)(this_mtd + 1);
 264                 strlcpy(this_mtd->mtd_id, mtd_id, mtd_id_len + 1);
 265
 266                 /* link into chain */
 267                 this_mtd->next = partitions;
 268                 partitions = this_mtd;
 269
 270                 dbg(("mtdid=<%s> num_parts=<%d>\n",
 271                      this_mtd->mtd_id, this_mtd->num_parts));
 272
 273
 274                 /* EOS - we're done */
 275                 if (*s == 0)
 276                         break;
 277
 278                 /* does another spec follow? */
 279                 if (*s != ';') {
 280                         pr_err("bad character after partition (%c)\n", *s);
 281                         return -EINVAL;
 282                 }
 283                 s++;
 284         }
 285
 286         return 0;
 287 }
 288
 289 /*
 290  * Main function to be called from the MTD mapping driver/device to
 291  * obtain the partitioning information. At this point the command line
 292  * arguments will actually be parsed and turned to struct mtd_partition
 293  * information. It returns partitions for the requested mtd device, or
 294  * the first one in the chain if a NULL mtd_id is passed in.
 295  */
 296 static int parse_cmdline_partitions(struct mtd_info *master,
 297                                     const struct mtd_partition **pparts,
 298                                     struct mtd_part_parser_data *data)
 299 {
 300         unsigned long long offset;
 301         int i, err;
 302         struct cmdline_mtd_partition *part;
 303         const char *mtd_id = master->name;
 304
 305         /* parse command line */
 306         if (!cmdline_parsed) {
 307                 err = mtdpart_setup_real(cmdline);
 308                 if (err)
 309                         return err;
 310         }
 311
 312         /*
 313          * Search for the partition definition matching master->name.
 314          * If master->name is not set, stop at first partition definition.
 315          */
 316         for (part = partitions; part; part = part->next) {
 317                 if ((!mtd_id) || (!strcmp(part->mtd_id, mtd_id)))
 318                         break;
 319         }
 320
 321         if (!part)
 322                 return 0;
 323
 324         for (i = 0, offset = 0; i < part->num_parts; i++) {
 325                 if (part->parts[i].offset == OFFSET_CONTINUOUS)
 326                         part->parts[i].offset = offset;
 327                 else
 328                         offset = part->parts[i].offset;
 329
 330                 if (part->parts[i].size == SIZE_REMAINING)
 331                         part->parts[i].size = master->size - offset;
 332
 333                 if (offset + part->parts[i].size > master->size) {
 334                         pr_warn("%s: partitioning exceeds flash size, truncating\n",
 335                                 part->mtd_id);
 336                         part->parts[i].size = master->size - offset;
 337                 }
 338                 offset += part->parts[i].size;
 339
 340                 if (part->parts[i].size == 0) {
 341                         pr_warn("%s: skipping zero sized partition\n",
 342                                 part->mtd_id);
 343                         part->num_parts--;
 344                         memmove(&part->parts[i], &part->parts[i + 1],
 345                                 sizeof(*part->parts) * (part->num_parts - i));
 346                         i--;
 347                 }
 348         }
 349
 350         *pparts = kmemdup(part->parts, sizeof(*part->parts) * part->num_parts,
 351                           GFP_KERNEL);
 352         if (!*pparts)
 353                 return -ENOMEM;
 354
 355         return part->num_parts;
 356 }
 357
 358
 359 /*
 360  * This is the handler for our kernel parameter, called from
 361  * main.c::checksetup(). Note that we can not yet kmalloc() anything,
 362  * so we only save the commandline for later processing.
 363  *
 364  * This function needs to be visible for bootloaders.
 365  */
 366 static int __init mtdpart_setup(char *s)
 367 {
 368         cmdline = s;
 369         return 1;
 370 }
 371
 372 __setup("mtdparts=", mtdpart_setup);
 373
 374 static struct mtd_part_parser cmdline_parser = {
 375         .parse_fn = parse_cmdline_partitions,
 376         .name = "cmdlinepart",
 377 };
 378
 379 static int __init cmdline_parser_init(void)
 380 {
 381         if (mtdparts)
 382                 mtdpart_setup(mtdparts);
 383         register_mtd_parser(&cmdline_parser);
 384         return 0;
 385 }
 386
 387 static void __exit cmdline_parser_exit(void)
 388 {
 389         deregister_mtd_parser(&cmdline_parser);
 390 }
 391
 392 module_init(cmdline_parser_init);
 393 module_exit(cmdline_parser_exit);
 394
 395 MODULE_PARM_DESC(mtdparts, "Partitioning specification");
 396 module_param(mtdparts, charp, 0);
 397
 398 MODULE_LICENSE("GPL");
 399 MODULE_AUTHOR("Marius Groeger <mag@sysgo.de>");
 400 MODULE_DESCRIPTION("Command line configuration of MTD partitions");