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
  46 #include <linux/mtd/mtd.h>
  47
  48 #define SLRAM_MAX_DEVICES_PARAMS 6              /* 3 parameters / device */
  49 #define SLRAM_BLK_SZ 0x4000
  50
  51 #define T(fmt, args...) printk(KERN_DEBUG fmt, ## args)
  52 #define E(fmt, args...) printk(KERN_NOTICE fmt, ## args)
  53
  54 typedef struct slram_priv {
  55         u_char *start;
  56         u_char *end;
  57 } slram_priv_t;
  58
  59 typedef struct slram_mtd_list {
  60         struct mtd_info *mtdinfo;
  61         struct slram_mtd_list *next;
  62 } slram_mtd_list_t;
  63
  64 #ifdef MODULE
  65 static char *map[SLRAM_MAX_DEVICES_PARAMS];
  66
  67 module_param_array(map, charp, NULL, 0);
  68 MODULE_PARM_DESC(map, "List of memory regions to map. \"map=<name>, <start>, <length / end>\"");
  69 #else
  70 static char *map;
  71 #endif
  72
  73 static slram_mtd_list_t *slram_mtdlist = NULL;
  74
  75 static int slram_erase(struct mtd_info *, struct erase_info *);
  76 static int slram_point(struct mtd_info *, loff_t, size_t, size_t *, void **,
  77                 resource_size_t *);
  78 static int slram_unpoint(struct mtd_info *, loff_t, size_t);
  79 static int slram_read(struct mtd_info *, loff_t, size_t, size_t *, u_char *);
  80 static int slram_write(struct mtd_info *, loff_t, size_t, size_t *, const u_char *);
  81
  82 static int slram_erase(struct mtd_info *mtd, struct erase_info *instr)
  83 {
  84         slram_priv_t *priv = mtd->priv;
  85
  86         memset(priv->start + instr->addr, 0xff, instr->len);
  87         /* This'll catch a few races. Free the thing before returning :)
  88          * I don't feel at all ashamed. This kind of thing is possible anyway
  89          * with flash, but unlikely.
  90          */
  91         instr->state = MTD_ERASE_DONE;
  92         mtd_erase_callback(instr);
  93         return(0);
  94 }
  95
  96 static int slram_point(struct mtd_info *mtd, loff_t from, size_t len,
  97                 size_t *retlen, void **virt, resource_size_t *phys)
  98 {
  99         slram_priv_t *priv = mtd->priv;
 100
 101         *virt = priv->start + from;
 102         *retlen = len;
 103         return(0);
 104 }
 105
 106 static int slram_unpoint(struct mtd_info *mtd, loff_t from, size_t len)
 107 {
 108         return 0;
 109 }
 110
 111 static int slram_read(struct mtd_info *mtd, loff_t from, size_t len,
 112                 size_t *retlen, u_char *buf)
 113 {
 114         slram_priv_t *priv = mtd->priv;
 115
 116         memcpy(buf, priv->start + from, len);
 117         *retlen = len;
 118         return(0);
 119 }
 120
 121 static int slram_write(struct mtd_info *mtd, loff_t to, size_t len,
 122                 size_t *retlen, const u_char *buf)
 123 {
 124         slram_priv_t *priv = mtd->priv;
 125
 126         memcpy(priv->start + to, buf, len);
 127         *retlen = len;
 128         return(0);
 129 }
 130
 131 /*====================================================================*/
 132
 133 static int register_device(char *name, unsigned long start, unsigned long length)
 134 {
 135         slram_mtd_list_t **curmtd;
 136
 137         curmtd = &slram_mtdlist;
 138         while (*curmtd) {
 139                 curmtd = &(*curmtd)->next;
 140         }
 141
 142         *curmtd = kmalloc(sizeof(slram_mtd_list_t), GFP_KERNEL);
 143         if (!(*curmtd)) {
 144                 E("slram: Cannot allocate new MTD device.\n");
 145                 return(-ENOMEM);
 146         }
 147         (*curmtd)->mtdinfo = kzalloc(sizeof(struct mtd_info), GFP_KERNEL);
 148         (*curmtd)->next = NULL;
 149
 150         if ((*curmtd)->mtdinfo) {
 151                 (*curmtd)->mtdinfo->priv =
 152                         kzalloc(sizeof(slram_priv_t), GFP_KERNEL);
 153
 154                 if (!(*curmtd)->mtdinfo->priv) {
 155                         kfree((*curmtd)->mtdinfo);
 156                         (*curmtd)->mtdinfo = NULL;
 157                 }
 158         }
 159
 160         if (!(*curmtd)->mtdinfo) {
 161                 E("slram: Cannot allocate new MTD device.\n");
 162                 return(-ENOMEM);
 163         }
 164
 165         if (!(((slram_priv_t *)(*curmtd)->mtdinfo->priv)->start =
 166                                 ioremap(start, length))) {
 167                 E("slram: ioremap failed\n");
 168                 return -EIO;
 169         }
 170         ((slram_priv_t *)(*curmtd)->mtdinfo->priv)->end =
 171                 ((slram_priv_t *)(*curmtd)->mtdinfo->priv)->start + length;
 172
 173
 174         (*curmtd)->mtdinfo->name = name;
 175         (*curmtd)->mtdinfo->size = length;
 176         (*curmtd)->mtdinfo->flags = MTD_CAP_RAM;
 177         (*curmtd)->mtdinfo->_erase = slram_erase;
 178         (*curmtd)->mtdinfo->_point = slram_point;
 179         (*curmtd)->mtdinfo->_unpoint = slram_unpoint;
 180         (*curmtd)->mtdinfo->_read = slram_read;
 181         (*curmtd)->mtdinfo->_write = slram_write;
 182         (*curmtd)->mtdinfo->owner = THIS_MODULE;
 183         (*curmtd)->mtdinfo->type = MTD_RAM;
 184         (*curmtd)->mtdinfo->erasesize = SLRAM_BLK_SZ;
 185         (*curmtd)->mtdinfo->writesize = 1;
 186
 187         if (mtd_device_register((*curmtd)->mtdinfo, NULL, 0))   {
 188                 E("slram: Failed to register new device\n");
 189                 iounmap(((slram_priv_t *)(*curmtd)->mtdinfo->priv)->start);
 190                 kfree((*curmtd)->mtdinfo->priv);
 191                 kfree((*curmtd)->mtdinfo);
 192                 return(-EAGAIN);
 193         }
 194         T("slram: Registered device %s from %luKiB to %luKiB\n", name,
 195                         (start / 1024), ((start + length) / 1024));
 196         T("slram: Mapped from 0x%p to 0x%p\n",
 197                         ((slram_priv_t *)(*curmtd)->mtdinfo->priv)->start,
 198                         ((slram_priv_t *)(*curmtd)->mtdinfo->priv)->end);
 199         return(0);
 200 }
 201
 202 static void unregister_devices(void)
 203 {
 204         slram_mtd_list_t *nextitem;
 205
 206         while (slram_mtdlist) {
 207                 nextitem = slram_mtdlist->next;
 208                 mtd_device_unregister(slram_mtdlist->mtdinfo);
 209                 iounmap(((slram_priv_t *)slram_mtdlist->mtdinfo->priv)->start);
 210                 kfree(slram_mtdlist->mtdinfo->priv);
 211                 kfree(slram_mtdlist->mtdinfo);
 212                 kfree(slram_mtdlist);
 213                 slram_mtdlist = nextitem;
 214         }
 215 }
 216
 217 static unsigned long handle_unit(unsigned long value, char *unit)
 218 {
 219         if ((*unit == 'M') || (*unit == 'm')) {
 220                 return(value * 1024 * 1024);
 221         } else if ((*unit == 'K') || (*unit == 'k')) {
 222                 return(value * 1024);
 223         }
 224         return(value);
 225 }
 226
 227 static int parse_cmdline(char *devname, char *szstart, char *szlength)
 228 {
 229         char *buffer;
 230         unsigned long devstart;
 231         unsigned long devlength;
 232
 233         if ((!devname) || (!szstart) || (!szlength)) {
 234                 unregister_devices();
 235                 return(-EINVAL);
 236         }
 237
 238         devstart = simple_strtoul(szstart, &buffer, 0);
 239         devstart = handle_unit(devstart, buffer);
 240
 241         if (*(szlength) != '+') {
 242                 devlength = simple_strtoul(szlength, &buffer, 0);
 243                 devlength = handle_unit(devlength, buffer);
 244                 if (devlength < devstart)
 245                         goto err_out;
 246
 247                 devlength -= devstart;
 248         } else {
 249                 devlength = simple_strtoul(szlength + 1, &buffer, 0);
 250                 devlength = handle_unit(devlength, buffer);
 251         }
 252         T("slram: devname=%s, devstart=0x%lx, devlength=0x%lx\n",
 253                         devname, devstart, devlength);
 254         if (devlength % SLRAM_BLK_SZ != 0)
 255                 goto err_out;
 256
 257         if ((devstart = register_device(devname, devstart, devlength))){
 258                 unregister_devices();
 259                 return((int)devstart);
 260         }
 261         return(0);
 262
 263 err_out:
 264         E("slram: Illegal length parameter.\n");
 265         return(-EINVAL);
 266 }
 267
 268 #ifndef MODULE
 269
 270 static int __init mtd_slram_setup(char *str)
 271 {
 272         map = str;
 273         return(1);
 274 }
 275
 276 __setup("slram=", mtd_slram_setup);
 277
 278 #endif
 279
 280 static int __init init_slram(void)
 281 {
 282         char *devname;
 283
 284 #ifndef MODULE
 285         char *devstart;
 286         char *devlength;
 287
 288         if (!map) {
 289                 E("slram: not enough parameters.\n");
 290                 return(-EINVAL);
 291         }
 292         while (map) {
 293                 devname = devstart = devlength = NULL;
 294
 295                 if (!(devname = strsep(&map, ","))) {
 296                         E("slram: No devicename specified.\n");
 297                         break;
 298                 }
 299                 T("slram: devname = %s\n", devname);
 300                 if ((!map) || (!(devstart = strsep(&map, ",")))) {
 301                         E("slram: No devicestart specified.\n");
 302                 }
 303                 T("slram: devstart = %s\n", devstart);
 304                 if ((!map) || (!(devlength = strsep(&map, ",")))) {
 305                         E("slram: No devicelength / -end specified.\n");
 306                 }
 307                 T("slram: devlength = %s\n", devlength);
 308                 if (parse_cmdline(devname, devstart, devlength) != 0) {
 309                         return(-EINVAL);
 310                 }
 311         }
 312 #else
 313         int count;
 314         int i;
 315
 316         for (count = 0; count < SLRAM_MAX_DEVICES_PARAMS && map[count];
 317                         count++) {
 318         }
 319
 320         if ((count % 3 != 0) || (count == 0)) {
 321                 E("slram: not enough parameters.\n");
 322                 return(-EINVAL);
 323         }
 324         for (i = 0; i < (count / 3); i++) {
 325                 devname = map[i * 3];
 326
 327                 if (parse_cmdline(devname, map[i * 3 + 1], map[i * 3 + 2])!=0) {
 328                         return(-EINVAL);
 329                 }
 330
 331         }
 332 #endif /* !MODULE */
 333
 334         return(0);
 335 }
 336
 337 static void __exit cleanup_slram(void)
 338 {
 339         unregister_devices();
 340 }
 341
 342 module_init(init_slram);
 343 module_exit(cleanup_slram);
 344
 345 MODULE_LICENSE("GPL");
 346 MODULE_AUTHOR("Jochen Schaeuble <psionic@psionic.de>");
 347 MODULE_DESCRIPTION("MTD driver for uncached system RAM");