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