drivers/mtd/devices/slram.c

   1 /*======================================================================
   2
   3   $Id: slram.c,v 1.33 2005/01/05 18:05:13 dwmw2 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
  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         *mtdbuf = priv->start + from;
 112         *retlen = len;
 113         return(0);
 114 }
 115
 116 static void slram_unpoint(struct mtd_info *mtd, u_char *addr, loff_t from, size_t len)
 117 {
 118 }
 119
 120 static int slram_read(struct mtd_info *mtd, loff_t from, size_t len,
 121                 size_t *retlen, u_char *buf)
 122 {
 123         slram_priv_t *priv = mtd->priv;
 124
 125         memcpy(buf, priv->start + from, len);
 126
 127         *retlen = len;
 128         return(0);
 129 }
 130
 131 static int slram_write(struct mtd_info *mtd, loff_t to, size_t len,
 132                 size_t *retlen, const u_char *buf)
 133 {
 134         slram_priv_t *priv = mtd->priv;
 135
 136         memcpy(priv->start + to, buf, len);
 137
 138         *retlen = len;
 139         return(0);
 140 }
 141
 142 /*====================================================================*/
 143
 144 static int register_device(char *name, unsigned long start, unsigned long length)
 145 {
 146         slram_mtd_list_t **curmtd;
 147
 148         curmtd = &slram_mtdlist;
 149         while (*curmtd) {
 150                 curmtd = &(*curmtd)->next;
 151         }
 152
 153         *curmtd = kmalloc(sizeof(slram_mtd_list_t), GFP_KERNEL);
 154         if (!(*curmtd)) {
 155                 E("slram: Cannot allocate new MTD device.\n");
 156                 return(-ENOMEM);
 157         }
 158         (*curmtd)->mtdinfo = kmalloc(sizeof(struct mtd_info), GFP_KERNEL);
 159         (*curmtd)->next = NULL;
 160
 161         if ((*curmtd)->mtdinfo) {
 162                 memset((char *)(*curmtd)->mtdinfo, 0, sizeof(struct mtd_info));
 163                 (*curmtd)->mtdinfo->priv =
 164                         kmalloc(sizeof(slram_priv_t), GFP_KERNEL);
 165
 166                 if (!(*curmtd)->mtdinfo->priv) {
 167                         kfree((*curmtd)->mtdinfo);
 168                         (*curmtd)->mtdinfo = NULL;
 169                 } else {
 170                         memset((*curmtd)->mtdinfo->priv,0,sizeof(slram_priv_t));
 171                 }
 172         }
 173
 174         if (!(*curmtd)->mtdinfo) {
 175                 E("slram: Cannot allocate new MTD device.\n");
 176                 return(-ENOMEM);
 177         }
 178
 179         if (!(((slram_priv_t *)(*curmtd)->mtdinfo->priv)->start =
 180                                 ioremap(start, length))) {
 181                 E("slram: ioremap failed\n");
 182                 return -EIO;
 183         }
 184         ((slram_priv_t *)(*curmtd)->mtdinfo->priv)->end =
 185                 ((slram_priv_t *)(*curmtd)->mtdinfo->priv)->start + length;
 186
 187
 188         (*curmtd)->mtdinfo->name = name;
 189         (*curmtd)->mtdinfo->size = length;
 190         (*curmtd)->mtdinfo->flags = MTD_CLEAR_BITS | MTD_SET_BITS |
 191                                         MTD_WRITEB_WRITEABLE | MTD_VOLATILE;
 192         (*curmtd)->mtdinfo->erase = slram_erase;
 193         (*curmtd)->mtdinfo->point = slram_point;
 194         (*curmtd)->mtdinfo->unpoint = slram_unpoint;
 195         (*curmtd)->mtdinfo->read = slram_read;
 196         (*curmtd)->mtdinfo->write = slram_write;
 197         (*curmtd)->mtdinfo->owner = THIS_MODULE;
 198         (*curmtd)->mtdinfo->type = MTD_RAM;
 199         (*curmtd)->mtdinfo->erasesize = 0x0;
 200
 201         if (add_mtd_device((*curmtd)->mtdinfo)) {
 202                 E("slram: Failed to register new device\n");
 203                 iounmap(((slram_priv_t *)(*curmtd)->mtdinfo->priv)->start);
 204                 kfree((*curmtd)->mtdinfo->priv);
 205                 kfree((*curmtd)->mtdinfo);
 206                 return(-EAGAIN);
 207         }
 208         T("slram: Registered device %s from %luKiB to %luKiB\n", name,
 209                         (start / 1024), ((start + length) / 1024));
 210         T("slram: Mapped from 0x%p to 0x%p\n",
 211                         ((slram_priv_t *)(*curmtd)->mtdinfo->priv)->start,
 212                         ((slram_priv_t *)(*curmtd)->mtdinfo->priv)->end);
 213         return(0);
 214 }
 215
 216 static void unregister_devices(void)
 217 {
 218         slram_mtd_list_t *nextitem;
 219
 220         while (slram_mtdlist) {
 221                 nextitem = slram_mtdlist->next;
 222                 del_mtd_device(slram_mtdlist->mtdinfo);
 223                 iounmap(((slram_priv_t *)slram_mtdlist->mtdinfo->priv)->start);
 224                 kfree(slram_mtdlist->mtdinfo->priv);
 225                 kfree(slram_mtdlist->mtdinfo);
 226                 kfree(slram_mtdlist);
 227                 slram_mtdlist = nextitem;
 228         }
 229 }
 230
 231 static unsigned long handle_unit(unsigned long value, char *unit)
 232 {
 233         if ((*unit == 'M') || (*unit == 'm')) {
 234                 return(value * 1024 * 1024);
 235         } else if ((*unit == 'K') || (*unit == 'k')) {
 236                 return(value * 1024);
 237         }
 238         return(value);
 239 }
 240
 241 static int parse_cmdline(char *devname, char *szstart, char *szlength)
 242 {
 243         char *buffer;
 244         unsigned long devstart;
 245         unsigned long devlength;
 246
 247         if ((!devname) || (!szstart) || (!szlength)) {
 248                 unregister_devices();
 249                 return(-EINVAL);
 250         }
 251
 252         devstart = simple_strtoul(szstart, &buffer, 0);
 253         devstart = handle_unit(devstart, buffer);
 254
 255         if (*(szlength) != '+') {
 256                 devlength = simple_strtoul(szlength, &buffer, 0);
 257                 devlength = handle_unit(devlength, buffer) - devstart;
 258         } else {
 259                 devlength = simple_strtoul(szlength + 1, &buffer, 0);
 260                 devlength = handle_unit(devlength, buffer);
 261         }
 262         T("slram: devname=%s, devstart=0x%lx, devlength=0x%lx\n",
 263                         devname, devstart, devlength);
 264         if ((devstart < 0) || (devlength < 0)) {
 265                 E("slram: Illegal start / length parameter.\n");
 266                 return(-EINVAL);
 267         }
 268
 269         if ((devstart = register_device(devname, devstart, devlength))){
 270                 unregister_devices();
 271                 return((int)devstart);
 272         }
 273         return(0);
 274 }
 275
 276 #ifndef MODULE
 277
 278 static int __init mtd_slram_setup(char *str)
 279 {
 280         map = str;
 281         return(1);
 282 }
 283
 284 __setup("slram=", mtd_slram_setup);
 285
 286 #endif
 287
 288 static int init_slram(void)
 289 {
 290         char *devname;
 291         int i;
 292
 293 #ifndef MODULE
 294         char *devstart;
 295         char *devlength;
 296
 297         i = 0;
 298
 299         if (!map) {
 300                 E("slram: not enough parameters.\n");
 301                 return(-EINVAL);
 302         }
 303         while (map) {
 304                 devname = devstart = devlength = NULL;
 305
 306                 if (!(devname = strsep(&map, ","))) {
 307                         E("slram: No devicename specified.\n");
 308                         break;
 309                 }
 310                 T("slram: devname = %s\n", devname);
 311                 if ((!map) || (!(devstart = strsep(&map, ",")))) {
 312                         E("slram: No devicestart specified.\n");
 313                 }
 314                 T("slram: devstart = %s\n", devstart);
 315                 if ((!map) || (!(devlength = strsep(&map, ",")))) {
 316                         E("slram: No devicelength / -end specified.\n");
 317                 }
 318                 T("slram: devlength = %s\n", devlength);
 319                 if (parse_cmdline(devname, devstart, devlength) != 0) {
 320                         return(-EINVAL);
 321                 }
 322         }
 323 #else
 324         int count;
 325
 326         for (count = 0; (map[count]) && (count < SLRAM_MAX_DEVICES_PARAMS);
 327                         count++) {
 328         }
 329
 330         if ((count % 3 != 0) || (count == 0)) {
 331                 E("slram: not enough parameters.\n");
 332                 return(-EINVAL);
 333         }
 334         for (i = 0; i < (count / 3); i++) {
 335                 devname = map[i * 3];
 336
 337                 if (parse_cmdline(devname, map[i * 3 + 1], map[i * 3 + 2])!=0) {
 338                         return(-EINVAL);
 339                 }
 340
 341         }
 342 #endif /* !MODULE */
 343
 344         return(0);
 345 }
 346
 347 static void __exit cleanup_slram(void)
 348 {
 349         unregister_devices();
 350 }
 351
 352 module_init(init_slram);
 353 module_exit(cleanup_slram);
 354
 355 MODULE_LICENSE("GPL");
 356 MODULE_AUTHOR("Jochen Schaeuble <psionic@psionic.de>");
 357 MODULE_DESCRIPTION("MTD driver for uncached system RAM");