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