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