drivers/mtd/devices/slram.c

   1 /*======================================================================
   2
   3   $Id: slram.c,v 1.36 2005/11/07 11:14:25 gleixner Exp $
   4
   5   This driver provides a method to access memory not used by the kernel
   6   itself (i.e. if the kernel commandline mem=xxx is used). To actually
   7   use slram at least mtdblock or mtdchar is required (for block or
   8   character device access).
   9
  10   Usage:
  11
  12   if compiled as loadable module:
  13     modprobe slram map=<name>,<start>,<end/offset>
  14   if statically linked into the kernel use the following kernel cmd.line
  15     slram=<name>,<start>,<end/offset>
  16
  17   <name>: name of the device that will be listed in /proc/mtd
  18   <start>: start of the memory region, decimal or hex (0xabcdef)
  19   <end/offset>: end of the memory region. It's possible to use +0x1234
  20                 to specify the offset instead of the absolute address
  21
  22   NOTE:
  23   With slram it's only possible to map a contigous memory region. Therfore
  24   if there's a device mapped somewhere in the region specified slram will
  25   fail to load (see kernel log if modprobe fails).
  26
  27   -
  28
  29   Jochen Schaeuble <psionic@psionic.de>
  30
  31 ======================================================================*/
  32
  33
  34 #include <linux/module.h>
  35 #include <asm/uaccess.h>
  36 #include <linux/types.h>
  37 #include <linux/kernel.h>
  38 #include <linux/sched.h>
  39 #include <linux/ptrace.h>
  40 #include <linux/slab.h>
  41 #include <linux/string.h>
  42 #include <linux/timer.h>
  43 #include <linux/major.h>
  44 #include <linux/fs.h>
  45 #include <linux/ioctl.h>
  46 #include <linux/init.h>
  47 #include <asm/io.h>
  48 #include <asm/system.h>
  49
  50 #include <linux/mtd/mtd.h>
  51
  52 #define SLRAM_MAX_DEVICES_PARAMS 6              /* 3 parameters / device */
  53 #define SLRAM_BLK_SZ 0x4000
  54
  55 #define T(fmt, args...) printk(KERN_DEBUG fmt, ## args)
  56 #define E(fmt, args...) printk(KERN_NOTICE fmt, ## args)
  57
  58 typedef struct slram_priv {
  59         u_char *start;
  60         u_char *end;
  61 } slram_priv_t;
  62
  63 typedef struct slram_mtd_list {
  64         struct mtd_info *mtdinfo;
  65         struct slram_mtd_list *next;
  66 } slram_mtd_list_t;
  67
  68 #ifdef MODULE
  69 static char *map[SLRAM_MAX_DEVICES_PARAMS];
  70
  71 module_param_array(map, charp, NULL, 0);
  72 MODULE_PARM_DESC(map, "List of memory regions to map. \"map=<name>, <start>, <length / end>\"");
  73 #else
  74 static char *map;
  75 #endif
  76
  77 static slram_mtd_list_t *slram_mtdlist = NULL;
  78
  79 static int slram_erase(struct mtd_info *, struct erase_info *);
  80 static int slram_point(struct mtd_info *, loff_t, size_t, size_t *, u_char **);
  81 static void slram_unpoint(struct mtd_info *, u_char *, loff_t,  size_t);
  82 static int slram_read(struct mtd_info *, loff_t, size_t, size_t *, u_char *);
  83 static int slram_write(struct mtd_info *, loff_t, size_t, size_t *, const u_char *);
  84
  85 static int slram_erase(struct mtd_info *mtd, struct erase_info *instr)
  86 {
  87         slram_priv_t *priv = mtd->priv;
  88
  89         if (instr->addr + instr->len > mtd->size) {
  90                 return(-EINVAL);
  91         }
  92
  93         memset(priv->start + instr->addr, 0xff, instr->len);
  94
  95         /* This'll catch a few races. Free the thing before returning :)
  96          * I don't feel at all ashamed. This kind of thing is possible anyway
  97          * with flash, but unlikely.
  98          */
  99
 100         instr->state = MTD_ERASE_DONE;
 101
 102         mtd_erase_callback(instr);
 103
 104         return(0);
 105 }
 106
 107 static int slram_point(struct mtd_info *mtd, loff_t from, size_t len,
 108                 size_t *retlen, u_char **mtdbuf)
 109 {
 110         slram_priv_t *priv = mtd->priv;
 111
 112         if (from + len > mtd->size)
 113                 return -EINVAL;
 114
 115         *mtdbuf = priv->start + from;
 116         *retlen = len;
 117         return(0);
 118 }
 119
 120 static void slram_unpoint(struct mtd_info *mtd, u_char *addr, loff_t from, size_t len)
 121 {
 122 }
 123
 124 static int slram_read(struct mtd_info *mtd, loff_t from, size_t len,
 125                 size_t *retlen, u_char *buf)
 126 {
 127         slram_priv_t *priv = mtd->priv;
 128
 129         if (from > mtd->size)
 130                 return -EINVAL;
 131
 132         if (from + len > mtd->size)
 133                 len = mtd->size - from;
 134
 135         memcpy(buf, priv->start + from, len);
 136
 137         *retlen = len;
 138         return(0);
 139 }
 140
 141 static int slram_write(struct mtd_info *mtd, loff_t to, size_t len,
 142                 size_t *retlen, const u_char *buf)
 143 {
 144         slram_priv_t *priv = mtd->priv;
 145
 146         if (to + len > mtd->size)
 147                 return -EINVAL;
 148
 149         memcpy(priv->start + to, buf, len);
 150
 151         *retlen = len;
 152         return(0);
 153 }
 154
 155 /*====================================================================*/
 156
 157 static int register_device(char *name, unsigned long start, unsigned long length)
 158 {
 159         slram_mtd_list_t **curmtd;
 160
 161         curmtd = &slram_mtdlist;
 162         while (*curmtd) {
 163                 curmtd = &(*curmtd)->next;
 164         }
 165
 166         *curmtd = kmalloc(sizeof(slram_mtd_list_t), GFP_KERNEL);
 167         if (!(*curmtd)) {
 168                 E("slram: Cannot allocate new MTD device.\n");
 169                 return(-ENOMEM);
 170         }
 171         (*curmtd)->mtdinfo = kzalloc(sizeof(struct mtd_info), GFP_KERNEL);
 172         (*curmtd)->next = NULL;
 173
 174         if ((*curmtd)->mtdinfo) {
 175                 (*curmtd)->mtdinfo->priv =
 176                         kzalloc(sizeof(slram_priv_t), GFP_KERNEL);
 177
 178                 if (!(*curmtd)->mtdinfo->priv) {
 179                         kfree((*curmtd)->mtdinfo);
 180                         (*curmtd)->mtdinfo = NULL;
 181                 }
 182         }
 183
 184         if (!(*curmtd)->mtdinfo) {
 185                 E("slram: Cannot allocate new MTD device.\n");
 186                 return(-ENOMEM);
 187         }
 188
 189         if (!(((slram_priv_t *)(*curmtd)->mtdinfo->priv)->start =
 190                                 ioremap(start, length))) {
 191                 E("slram: ioremap failed\n");
 192                 return -EIO;
 193         }
 194         ((slram_priv_t *)(*curmtd)->mtdinfo->priv)->end =
 195                 ((slram_priv_t *)(*curmtd)->mtdinfo->priv)->start + length;
 196
 197
 198         (*curmtd)->mtdinfo->name = name;
 199         (*curmtd)->mtdinfo->size = length;
 200         (*curmtd)->mtdinfo->flags = MTD_CAP_RAM;
 201         (*curmtd)->mtdinfo->erase = slram_erase;
 202         (*curmtd)->mtdinfo->point = slram_point;
 203         (*curmtd)->mtdinfo->unpoint = slram_unpoint;
 204         (*curmtd)->mtdinfo->read = slram_read;
 205         (*curmtd)->mtdinfo->write = slram_write;
 206         (*curmtd)->mtdinfo->owner = THIS_MODULE;
 207         (*curmtd)->mtdinfo->type = MTD_RAM;
 208         (*curmtd)->mtdinfo->erasesize = SLRAM_BLK_SZ;
 209         (*curmtd)->mtdinfo->writesize = 1;
 210
 211         if (add_mtd_device((*curmtd)->mtdinfo)) {
 212                 E("slram: Failed to register new device\n");
 213                 iounmap(((slram_priv_t *)(*curmtd)->mtdinfo->priv)->start);
 214                 kfree((*curmtd)->mtdinfo->priv);
 215                 kfree((*curmtd)->mtdinfo);
 216                 return(-EAGAIN);
 217         }
 218         T("slram: Registered device %s from %luKiB to %luKiB\n", name,
 219                         (start / 1024), ((start + length) / 1024));
 220         T("slram: Mapped from 0x%p to 0x%p\n",
 221                         ((slram_priv_t *)(*curmtd)->mtdinfo->priv)->start,
 222                         ((slram_priv_t *)(*curmtd)->mtdinfo->priv)->end);
 223         return(0);
 224 }
 225
 226 static void unregister_devices(void)
 227 {
 228         slram_mtd_list_t *nextitem;
 229
 230         while (slram_mtdlist) {
 231                 nextitem = slram_mtdlist->next;
 232                 del_mtd_device(slram_mtdlist->mtdinfo);
 233                 iounmap(((slram_priv_t *)slram_mtdlist->mtdinfo->priv)->start);
 234                 kfree(slram_mtdlist->mtdinfo->priv);
 235                 kfree(slram_mtdlist->mtdinfo);
 236                 kfree(slram_mtdlist);
 237                 slram_mtdlist = nextitem;
 238         }
 239 }
 240
 241 static unsigned long handle_unit(unsigned long value, char *unit)
 242 {
 243         if ((*unit == 'M') || (*unit == 'm')) {
 244                 return(value * 1024 * 1024);
 245         } else if ((*unit == 'K') || (*unit == 'k')) {
 246                 return(value * 1024);
 247         }
 248         return(value);
 249 }
 250
 251 static int parse_cmdline(char *devname, char *szstart, char *szlength)
 252 {
 253         char *buffer;
 254         unsigned long devstart;
 255         unsigned long devlength;
 256
 257         if ((!devname) || (!szstart) || (!szlength)) {
 258                 unregister_devices();
 259                 return(-EINVAL);
 260         }
 261
 262         devstart = simple_strtoul(szstart, &buffer, 0);
 263         devstart = handle_unit(devstart, buffer);
 264
 265         if (*(szlength) != '+') {
 266                 devlength = simple_strtoul(szlength, &buffer, 0);
 267                 devlength = handle_unit(devlength, buffer) - devstart;
 268         } else {
 269                 devlength = simple_strtoul(szlength + 1, &buffer, 0);
 270                 devlength = handle_unit(devlength, buffer);
 271         }
 272         T("slram: devname=%s, devstart=0x%lx, devlength=0x%lx\n",
 273                         devname, devstart, devlength);
 274         if ((devstart < 0) || (devlength < 0) || (devlength % SLRAM_BLK_SZ != 0)) {
 275                 E("slram: Illegal start / length parameter.\n");
 276                 return(-EINVAL);
 277         }
 278
 279         if ((devstart = register_device(devname, devstart, devlength))){
 280                 unregister_devices();
 281                 return((int)devstart);
 282         }
 283         return(0);
 284 }
 285
 286 #ifndef MODULE
 287
 288 static int __init mtd_slram_setup(char *str)
 289 {
 290         map = str;
 291         return(1);
 292 }
 293
 294 __setup("slram=", mtd_slram_setup);
 295
 296 #endif
 297
 298 static int init_slram(void)
 299 {
 300         char *devname;
 301         int i;
 302
 303 #ifndef MODULE
 304         char *devstart;
 305         char *devlength;
 306
 307         i = 0;
 308
 309         if (!map) {
 310                 E("slram: not enough parameters.\n");
 311                 return(-EINVAL);
 312         }
 313         while (map) {
 314                 devname = devstart = devlength = NULL;
 315
 316                 if (!(devname = strsep(&map, ","))) {
 317                         E("slram: No devicename specified.\n");
 318                         break;
 319                 }
 320                 T("slram: devname = %s\n", devname);
 321                 if ((!map) || (!(devstart = strsep(&map, ",")))) {
 322                         E("slram: No devicestart specified.\n");
 323                 }
 324                 T("slram: devstart = %s\n", devstart);
 325                 if ((!map) || (!(devlength = strsep(&map, ",")))) {
 326                         E("slram: No devicelength / -end specified.\n");
 327                 }
 328                 T("slram: devlength = %s\n", devlength);
 329                 if (parse_cmdline(devname, devstart, devlength) != 0) {
 330                         return(-EINVAL);
 331                 }
 332         }
 333 #else
 334         int count;
 335
 336         for (count = 0; (map[count]) && (count < SLRAM_MAX_DEVICES_PARAMS);
 337                         count++) {
 338         }
 339
 340         if ((count % 3 != 0) || (count == 0)) {
 341                 E("slram: not enough parameters.\n");
 342                 return(-EINVAL);
 343         }
 344         for (i = 0; i < (count / 3); i++) {
 345                 devname = map[i * 3];
 346
 347                 if (parse_cmdline(devname, map[i * 3 + 1], map[i * 3 + 2])!=0) {
 348                         return(-EINVAL);
 349                 }
 350
 351         }
 352 #endif /* !MODULE */
 353
 354         return(0);
 355 }
 356
 357 static void __exit cleanup_slram(void)
 358 {
 359         unregister_devices();
 360 }
 361
 362 module_init(init_slram);
 363 module_exit(cleanup_slram);
 364
 365 MODULE_LICENSE("GPL");
 366 MODULE_AUTHOR("Jochen Schaeuble <psionic@psionic.de>");
 367 MODULE_DESCRIPTION("MTD driver for uncached system RAM");