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 *, void **,
  80                 resource_size_t *);
  81 static void slram_unpoint(struct mtd_info *, 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, void **virt, resource_size_t *phys)
 109 {
 110         slram_priv_t *priv = mtd->priv;
 111
 112         /* can we return a physical address with this driver? */
 113         if (phys)
 114                 return -EINVAL;
 115
 116         if (from + len > mtd->size)
 117                 return -EINVAL;
 118
 119         *virt = priv->start + from;
 120         *retlen = len;
 121         return(0);
 122 }
 123
 124 static void slram_unpoint(struct mtd_info *mtd, loff_t from, size_t len)
 125 {
 126 }
 127
 128 static int slram_read(struct mtd_info *mtd, loff_t from, size_t len,
 129                 size_t *retlen, u_char *buf)
 130 {
 131         slram_priv_t *priv = mtd->priv;
 132
 133         if (from > mtd->size)
 134                 return -EINVAL;
 135
 136         if (from + len > mtd->size)
 137                 len = mtd->size - from;
 138
 139         memcpy(buf, priv->start + from, len);
 140
 141         *retlen = len;
 142         return(0);
 143 }
 144
 145 static int slram_write(struct mtd_info *mtd, loff_t to, size_t len,
 146                 size_t *retlen, const u_char *buf)
 147 {
 148         slram_priv_t *priv = mtd->priv;
 149
 150         if (to + len > mtd->size)
 151                 return -EINVAL;
 152
 153         memcpy(priv->start + to, buf, len);
 154
 155         *retlen = len;
 156         return(0);
 157 }
 158
 159 /*====================================================================*/
 160
 161 static int register_device(char *name, unsigned long start, unsigned long length)
 162 {
 163         slram_mtd_list_t **curmtd;
 164
 165         curmtd = &slram_mtdlist;
 166         while (*curmtd) {
 167                 curmtd = &(*curmtd)->next;
 168         }
 169
 170         *curmtd = kmalloc(sizeof(slram_mtd_list_t), GFP_KERNEL);
 171         if (!(*curmtd)) {
 172                 E("slram: Cannot allocate new MTD device.\n");
 173                 return(-ENOMEM);
 174         }
 175         (*curmtd)->mtdinfo = kzalloc(sizeof(struct mtd_info), GFP_KERNEL);
 176         (*curmtd)->next = NULL;
 177
 178         if ((*curmtd)->mtdinfo) {
 179                 (*curmtd)->mtdinfo->priv =
 180                         kzalloc(sizeof(slram_priv_t), GFP_KERNEL);
 181
 182                 if (!(*curmtd)->mtdinfo->priv) {
 183                         kfree((*curmtd)->mtdinfo);
 184                         (*curmtd)->mtdinfo = NULL;
 185                 }
 186         }
 187
 188         if (!(*curmtd)->mtdinfo) {
 189                 E("slram: Cannot allocate new MTD device.\n");
 190                 return(-ENOMEM);
 191         }
 192
 193         if (!(((slram_priv_t *)(*curmtd)->mtdinfo->priv)->start =
 194                                 ioremap(start, length))) {
 195                 E("slram: ioremap failed\n");
 196                 return -EIO;
 197         }
 198         ((slram_priv_t *)(*curmtd)->mtdinfo->priv)->end =
 199                 ((slram_priv_t *)(*curmtd)->mtdinfo->priv)->start + length;
 200
 201
 202         (*curmtd)->mtdinfo->name = name;
 203         (*curmtd)->mtdinfo->size = length;
 204         (*curmtd)->mtdinfo->flags = MTD_CAP_RAM;
 205         (*curmtd)->mtdinfo->erase = slram_erase;
 206         (*curmtd)->mtdinfo->point = slram_point;
 207         (*curmtd)->mtdinfo->unpoint = slram_unpoint;
 208         (*curmtd)->mtdinfo->read = slram_read;
 209         (*curmtd)->mtdinfo->write = slram_write;
 210         (*curmtd)->mtdinfo->owner = THIS_MODULE;
 211         (*curmtd)->mtdinfo->type = MTD_RAM;
 212         (*curmtd)->mtdinfo->erasesize = SLRAM_BLK_SZ;
 213         (*curmtd)->mtdinfo->writesize = 1;
 214
 215         if (add_mtd_device((*curmtd)->mtdinfo)) {
 216                 E("slram: Failed to register new device\n");
 217                 iounmap(((slram_priv_t *)(*curmtd)->mtdinfo->priv)->start);
 218                 kfree((*curmtd)->mtdinfo->priv);
 219                 kfree((*curmtd)->mtdinfo);
 220                 return(-EAGAIN);
 221         }
 222         T("slram: Registered device %s from %luKiB to %luKiB\n", name,
 223                         (start / 1024), ((start + length) / 1024));
 224         T("slram: Mapped from 0x%p to 0x%p\n",
 225                         ((slram_priv_t *)(*curmtd)->mtdinfo->priv)->start,
 226                         ((slram_priv_t *)(*curmtd)->mtdinfo->priv)->end);
 227         return(0);
 228 }
 229
 230 static void unregister_devices(void)
 231 {
 232         slram_mtd_list_t *nextitem;
 233
 234         while (slram_mtdlist) {
 235                 nextitem = slram_mtdlist->next;
 236                 del_mtd_device(slram_mtdlist->mtdinfo);
 237                 iounmap(((slram_priv_t *)slram_mtdlist->mtdinfo->priv)->start);
 238                 kfree(slram_mtdlist->mtdinfo->priv);
 239                 kfree(slram_mtdlist->mtdinfo);
 240                 kfree(slram_mtdlist);
 241                 slram_mtdlist = nextitem;
 242         }
 243 }
 244
 245 static unsigned long handle_unit(unsigned long value, char *unit)
 246 {
 247         if ((*unit == 'M') || (*unit == 'm')) {
 248                 return(value * 1024 * 1024);
 249         } else if ((*unit == 'K') || (*unit == 'k')) {
 250                 return(value * 1024);
 251         }
 252         return(value);
 253 }
 254
 255 static int parse_cmdline(char *devname, char *szstart, char *szlength)
 256 {
 257         char *buffer;
 258         unsigned long devstart;
 259         unsigned long devlength;
 260
 261         if ((!devname) || (!szstart) || (!szlength)) {
 262                 unregister_devices();
 263                 return(-EINVAL);
 264         }
 265
 266         devstart = simple_strtoul(szstart, &buffer, 0);
 267         devstart = handle_unit(devstart, buffer);
 268
 269         if (*(szlength) != '+') {
 270                 devlength = simple_strtoul(szlength, &buffer, 0);
 271                 devlength = handle_unit(devlength, buffer) - devstart;
 272         } else {
 273                 devlength = simple_strtoul(szlength + 1, &buffer, 0);
 274                 devlength = handle_unit(devlength, buffer);
 275         }
 276         T("slram: devname=%s, devstart=0x%lx, devlength=0x%lx\n",
 277                         devname, devstart, devlength);
 278         if ((devstart < 0) || (devlength < 0) || (devlength % SLRAM_BLK_SZ != 0)) {
 279                 E("slram: Illegal start / length parameter.\n");
 280                 return(-EINVAL);
 281         }
 282
 283         if ((devstart = register_device(devname, devstart, devlength))){
 284                 unregister_devices();
 285                 return((int)devstart);
 286         }
 287         return(0);
 288 }
 289
 290 #ifndef MODULE
 291
 292 static int __init mtd_slram_setup(char *str)
 293 {
 294         map = str;
 295         return(1);
 296 }
 297
 298 __setup("slram=", mtd_slram_setup);
 299
 300 #endif
 301
 302 static int init_slram(void)
 303 {
 304         char *devname;
 305         int i;
 306
 307 #ifndef MODULE
 308         char *devstart;
 309         char *devlength;
 310
 311         i = 0;
 312
 313         if (!map) {
 314                 E("slram: not enough parameters.\n");
 315                 return(-EINVAL);
 316         }
 317         while (map) {
 318                 devname = devstart = devlength = NULL;
 319
 320                 if (!(devname = strsep(&map, ","))) {
 321                         E("slram: No devicename specified.\n");
 322                         break;
 323                 }
 324                 T("slram: devname = %s\n", devname);
 325                 if ((!map) || (!(devstart = strsep(&map, ",")))) {
 326                         E("slram: No devicestart specified.\n");
 327                 }
 328                 T("slram: devstart = %s\n", devstart);
 329                 if ((!map) || (!(devlength = strsep(&map, ",")))) {
 330                         E("slram: No devicelength / -end specified.\n");
 331                 }
 332                 T("slram: devlength = %s\n", devlength);
 333                 if (parse_cmdline(devname, devstart, devlength) != 0) {
 334                         return(-EINVAL);
 335                 }
 336         }
 337 #else
 338         int count;
 339
 340         for (count = 0; (map[count]) && (count < SLRAM_MAX_DEVICES_PARAMS);
 341                         count++) {
 342         }
 343
 344         if ((count % 3 != 0) || (count == 0)) {
 345                 E("slram: not enough parameters.\n");
 346                 return(-EINVAL);
 347         }
 348         for (i = 0; i < (count / 3); i++) {
 349                 devname = map[i * 3];
 350
 351                 if (parse_cmdline(devname, map[i * 3 + 1], map[i * 3 + 2])!=0) {
 352                         return(-EINVAL);
 353                 }
 354
 355         }
 356 #endif /* !MODULE */
 357
 358         return(0);
 359 }
 360
 361 static void __exit cleanup_slram(void)
 362 {
 363         unregister_devices();
 364 }
 365
 366 module_init(init_slram);
 367 module_exit(cleanup_slram);
 368
 369 MODULE_LICENSE("GPL");
 370 MODULE_AUTHOR("Jochen Schaeuble <psionic@psionic.de>");
 371 MODULE_DESCRIPTION("MTD driver for uncached system RAM");