drivers/mtd/devices/slram.c

   1 /*======================================================================
   2
   3   This driver provides a method to access memory not used by the kernel
   4   itself (i.e. if the kernel commandline mem=xxx is used). To actually
   5   use slram at least mtdblock or mtdchar is required (for block or
   6   character device access).
   7
   8   Usage:
   9
  10   if compiled as loadable module:
  11     modprobe slram map=<name>,<start>,<end/offset>
  12   if statically linked into the kernel use the following kernel cmd.line
  13     slram=<name>,<start>,<end/offset>
  14
  15   <name>: name of the device that will be listed in /proc/mtd
  16   <start>: start of the memory region, decimal or hex (0xabcdef)
  17   <end/offset>: end of the memory region. It's possible to use +0x1234
  18                 to specify the offset instead of the absolute address
  19
  20   NOTE:
  21   With slram it's only possible to map a contiguous memory region. Therefore
  22   if there's a device mapped somewhere in the region specified slram will
  23   fail to load (see kernel log if modprobe fails).
  24
  25   -
  26
  27   Jochen Schaeuble <psionic@psionic.de>
  28
  29 ======================================================================*/
  30
  31
  32 #include <linux/module.h>
  33 #include <asm/uaccess.h>
  34 #include <linux/types.h>
  35 #include <linux/kernel.h>
  36 #include <linux/ptrace.h>
  37 #include <linux/slab.h>
  38 #include <linux/string.h>
  39 #include <linux/timer.h>
  40 #include <linux/major.h>
  41 #include <linux/fs.h>
  42 #include <linux/ioctl.h>
  43 #include <linux/init.h>
  44 #include <asm/io.h>
  45 #include <asm/system.h>
  46
  47 #include <linux/mtd/mtd.h>
  48
  49 #define SLRAM_MAX_DEVICES_PARAMS 6              /* 3 parameters / device */
  50 #define SLRAM_BLK_SZ 0x4000
  51
  52 #define T(fmt, args...) printk(KERN_DEBUG fmt, ## args)
  53 #define E(fmt, args...) printk(KERN_NOTICE fmt, ## args)
  54
  55 typedef struct slram_priv {
  56         u_char *start;
  57         u_char *end;
  58 } slram_priv_t;
  59
  60 typedef struct slram_mtd_list {
  61         struct mtd_info *mtdinfo;
  62         struct slram_mtd_list *next;
  63 } slram_mtd_list_t;
  64
  65 #ifdef MODULE
  66 static char *map[SLRAM_MAX_DEVICES_PARAMS];
  67
  68 module_param_array(map, charp, NULL, 0);
  69 MODULE_PARM_DESC(map, "List of memory regions to map. \"map=<name>, <start>, <length / end>\"");
  70 #else
  71 static char *map;
  72 #endif
  73
  74 static slram_mtd_list_t *slram_mtdlist = NULL;
  75
  76 static int slram_erase(struct mtd_info *, struct erase_info *);
  77 static int slram_point(struct mtd_info *, loff_t, size_t, size_t *, void **,
  78                 resource_size_t *);
  79 static void slram_unpoint(struct mtd_info *, loff_t, size_t);
  80 static int slram_read(struct mtd_info *, loff_t, size_t, size_t *, u_char *);
  81 static int slram_write(struct mtd_info *, loff_t, size_t, size_t *, const u_char *);
  82
  83 static int slram_erase(struct mtd_info *mtd, struct erase_info *instr)
  84 {
  85         slram_priv_t *priv = mtd->priv;
  86
  87         if (instr->addr + instr->len > mtd->size) {
  88                 return(-EINVAL);
  89         }
  90
  91         memset(priv->start + instr->addr, 0xff, instr->len);
  92
  93         /* This'll catch a few races. Free the thing before returning :)
  94          * I don't feel at all ashamed. This kind of thing is possible anyway
  95          * with flash, but unlikely.
  96          */
  97
  98         instr->state = MTD_ERASE_DONE;
  99
 100         mtd_erase_callback(instr);
 101
 102         return(0);
 103 }
 104
 105 static int slram_point(struct mtd_info *mtd, loff_t from, size_t len,
 106                 size_t *retlen, void **virt, resource_size_t *phys)
 107 {
 108         slram_priv_t *priv = mtd->priv;
 109
 110         /* can we return a physical address with this driver? */
 111         if (phys)
 112                 return -EINVAL;
 113
 114         if (from + len > mtd->size)
 115                 return -EINVAL;
 116
 117         *virt = priv->start + from;
 118         *retlen = len;
 119         return(0);
 120 }
 121
 122 static void slram_unpoint(struct mtd_info *mtd, loff_t from, size_t len)
 123 {
 124 }
 125
 126 static int slram_read(struct mtd_info *mtd, loff_t from, size_t len,
 127                 size_t *retlen, u_char *buf)
 128 {
 129         slram_priv_t *priv = mtd->priv;
 130
 131         if (from > mtd->size)
 132                 return -EINVAL;
 133
 134         if (from + len > mtd->size)
 135                 len = mtd->size - from;
 136
 137         memcpy(buf, priv->start + from, len);
 138
 139         *retlen = len;
 140         return(0);
 141 }
 142
 143 static int slram_write(struct mtd_info *mtd, loff_t to, size_t len,
 144                 size_t *retlen, const u_char *buf)
 145 {
 146         slram_priv_t *priv = mtd->priv;
 147
 148         if (to + len > mtd->size)
 149                 return -EINVAL;
 150
 151         memcpy(priv->start + to, buf, len);
 152
 153         *retlen = len;
 154         return(0);
 155 }
 156
 157 /*====================================================================*/
 158
 159 static int register_device(char *name, unsigned long start, unsigned long length)
 160 {
 161         slram_mtd_list_t **curmtd;
 162
 163         curmtd = &slram_mtdlist;
 164         while (*curmtd) {
 165                 curmtd = &(*curmtd)->next;
 166         }
 167
 168         *curmtd = kmalloc(sizeof(slram_mtd_list_t), GFP_KERNEL);
 169         if (!(*curmtd)) {
 170                 E("slram: Cannot allocate new MTD device.\n");
 171                 return(-ENOMEM);
 172         }
 173         (*curmtd)->mtdinfo = kzalloc(sizeof(struct mtd_info), GFP_KERNEL);
 174         (*curmtd)->next = NULL;
 175
 176         if ((*curmtd)->mtdinfo) {
 177                 (*curmtd)->mtdinfo->priv =
 178                         kzalloc(sizeof(slram_priv_t), GFP_KERNEL);
 179
 180                 if (!(*curmtd)->mtdinfo->priv) {
 181                         kfree((*curmtd)->mtdinfo);
 182                         (*curmtd)->mtdinfo = NULL;
 183                 }
 184         }
 185
 186         if (!(*curmtd)->mtdinfo) {
 187                 E("slram: Cannot allocate new MTD device.\n");
 188                 return(-ENOMEM);
 189         }
 190
 191         if (!(((slram_priv_t *)(*curmtd)->mtdinfo->priv)->start =
 192                                 ioremap(start, length))) {
 193                 E("slram: ioremap failed\n");
 194                 return -EIO;
 195         }
 196         ((slram_priv_t *)(*curmtd)->mtdinfo->priv)->end =
 197                 ((slram_priv_t *)(*curmtd)->mtdinfo->priv)->start + length;
 198
 199
 200         (*curmtd)->mtdinfo->name = name;
 201         (*curmtd)->mtdinfo->size = length;
 202         (*curmtd)->mtdinfo->flags = MTD_CAP_RAM;
 203         (*curmtd)->mtdinfo->erase = slram_erase;
 204         (*curmtd)->mtdinfo->point = slram_point;
 205         (*curmtd)->mtdinfo->unpoint = slram_unpoint;
 206         (*curmtd)->mtdinfo->read = slram_read;
 207         (*curmtd)->mtdinfo->write = slram_write;
 208         (*curmtd)->mtdinfo->owner = THIS_MODULE;
 209         (*curmtd)->mtdinfo->type = MTD_RAM;
 210         (*curmtd)->mtdinfo->erasesize = SLRAM_BLK_SZ;
 211         (*curmtd)->mtdinfo->writesize = 1;
 212
 213         if (mtd_device_register((*curmtd)->mtdinfo, NULL, 0))   {
 214                 E("slram: Failed to register new device\n");
 215                 iounmap(((slram_priv_t *)(*curmtd)->mtdinfo->priv)->start);
 216                 kfree((*curmtd)->mtdinfo->priv);
 217                 kfree((*curmtd)->mtdinfo);
 218                 return(-EAGAIN);
 219         }
 220         T("slram: Registered device %s from %luKiB to %luKiB\n", name,
 221                         (start / 1024), ((start + length) / 1024));
 222         T("slram: Mapped from 0x%p to 0x%p\n",
 223                         ((slram_priv_t *)(*curmtd)->mtdinfo->priv)->start,
 224                         ((slram_priv_t *)(*curmtd)->mtdinfo->priv)->end);
 225         return(0);
 226 }
 227
 228 static void unregister_devices(void)
 229 {
 230         slram_mtd_list_t *nextitem;
 231
 232         while (slram_mtdlist) {
 233                 nextitem = slram_mtdlist->next;
 234                 mtd_device_unregister(slram_mtdlist->mtdinfo);
 235                 iounmap(((slram_priv_t *)slram_mtdlist->mtdinfo->priv)->start);
 236                 kfree(slram_mtdlist->mtdinfo->priv);
 237                 kfree(slram_mtdlist->mtdinfo);
 238                 kfree(slram_mtdlist);
 239                 slram_mtdlist = nextitem;
 240         }
 241 }
 242
 243 static unsigned long handle_unit(unsigned long value, char *unit)
 244 {
 245         if ((*unit == 'M') || (*unit == 'm')) {
 246                 return(value * 1024 * 1024);
 247         } else if ((*unit == 'K') || (*unit == 'k')) {
 248                 return(value * 1024);
 249         }
 250         return(value);
 251 }
 252
 253 static int parse_cmdline(char *devname, char *szstart, char *szlength)
 254 {
 255         char *buffer;
 256         unsigned long devstart;
 257         unsigned long devlength;
 258
 259         if ((!devname) || (!szstart) || (!szlength)) {
 260                 unregister_devices();
 261                 return(-EINVAL);
 262         }
 263
 264         devstart = simple_strtoul(szstart, &buffer, 0);
 265         devstart = handle_unit(devstart, buffer);
 266
 267         if (*(szlength) != '+') {
 268                 devlength = simple_strtoul(szlength, &buffer, 0);
 269                 devlength = handle_unit(devlength, buffer) - devstart;
 270                 if (devlength < devstart)
 271                         goto err_out;
 272
 273                 devlength -= devstart;
 274         } else {
 275                 devlength = simple_strtoul(szlength + 1, &buffer, 0);
 276                 devlength = handle_unit(devlength, buffer);
 277         }
 278         T("slram: devname=%s, devstart=0x%lx, devlength=0x%lx\n",
 279                         devname, devstart, devlength);
 280         if (devlength % SLRAM_BLK_SZ != 0)
 281                 goto err_out;
 282
 283         if ((devstart = register_device(devname, devstart, devlength))){
 284                 unregister_devices();
 285                 return((int)devstart);
 286         }
 287         return(0);
 288
 289 err_out:
 290         E("slram: Illegal length parameter.\n");
 291         return(-EINVAL);
 292 }
 293
 294 #ifndef MODULE
 295
 296 static int __init mtd_slram_setup(char *str)
 297 {
 298         map = str;
 299         return(1);
 300 }
 301
 302 __setup("slram=", mtd_slram_setup);
 303
 304 #endif
 305
 306 static int __init init_slram(void)
 307 {
 308         char *devname;
 309         int i;
 310
 311 #ifndef MODULE
 312         char *devstart;
 313         char *devlength;
 314
 315         i = 0;
 316
 317         if (!map) {
 318                 E("slram: not enough parameters.\n");
 319                 return(-EINVAL);
 320         }
 321         while (map) {
 322                 devname = devstart = devlength = NULL;
 323
 324                 if (!(devname = strsep(&map, ","))) {
 325                         E("slram: No devicename specified.\n");
 326                         break;
 327                 }
 328                 T("slram: devname = %s\n", devname);
 329                 if ((!map) || (!(devstart = strsep(&map, ",")))) {
 330                         E("slram: No devicestart specified.\n");
 331                 }
 332                 T("slram: devstart = %s\n", devstart);
 333                 if ((!map) || (!(devlength = strsep(&map, ",")))) {
 334                         E("slram: No devicelength / -end specified.\n");
 335                 }
 336                 T("slram: devlength = %s\n", devlength);
 337                 if (parse_cmdline(devname, devstart, devlength) != 0) {
 338                         return(-EINVAL);
 339                 }
 340         }
 341 #else
 342         int count;
 343
 344         for (count = 0; count < SLRAM_MAX_DEVICES_PARAMS && map[count];
 345                         count++) {
 346         }
 347
 348         if ((count % 3 != 0) || (count == 0)) {
 349                 E("slram: not enough parameters.\n");
 350                 return(-EINVAL);
 351         }
 352         for (i = 0; i < (count / 3); i++) {
 353                 devname = map[i * 3];
 354
 355                 if (parse_cmdline(devname, map[i * 3 + 1], map[i * 3 + 2])!=0) {
 356                         return(-EINVAL);
 357                 }
 358
 359         }
 360 #endif /* !MODULE */
 361
 362         return(0);
 363 }
 364
 365 static void __exit cleanup_slram(void)
 366 {
 367         unregister_devices();
 368 }
 369
 370 module_init(init_slram);
 371 module_exit(cleanup_slram);
 372
 373 MODULE_LICENSE("GPL");
 374 MODULE_AUTHOR("Jochen Schaeuble <psionic@psionic.de>");
 375 MODULE_DESCRIPTION("MTD driver for uncached system RAM");