drivers/mtd/devices/slram.c

   1 /*======================================================================
   2
   3   $Id: slram.c,v 1.34 2005/01/06 21:16:42 jwboyer 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 = kmalloc(sizeof(struct mtd_info), GFP_KERNEL);
 172         (*curmtd)->next = NULL;
 173
 174         if ((*curmtd)->mtdinfo) {
 175                 memset((char *)(*curmtd)->mtdinfo, 0, sizeof(struct mtd_info));
 176                 (*curmtd)->mtdinfo->priv =
 177                         kmalloc(sizeof(slram_priv_t), GFP_KERNEL);
 178
 179                 if (!(*curmtd)->mtdinfo->priv) {
 180                         kfree((*curmtd)->mtdinfo);
 181                         (*curmtd)->mtdinfo = NULL;
 182                 } else {
 183                         memset((*curmtd)->mtdinfo->priv,0,sizeof(slram_priv_t));
 184                 }
 185         }
 186
 187         if (!(*curmtd)->mtdinfo) {
 188                 E("slram: Cannot allocate new MTD device.\n");
 189                 return(-ENOMEM);
 190         }
 191
 192         if (!(((slram_priv_t *)(*curmtd)->mtdinfo->priv)->start =
 193                                 ioremap(start, length))) {
 194                 E("slram: ioremap failed\n");
 195                 return -EIO;
 196         }
 197         ((slram_priv_t *)(*curmtd)->mtdinfo->priv)->end =
 198                 ((slram_priv_t *)(*curmtd)->mtdinfo->priv)->start + length;
 199
 200
 201         (*curmtd)->mtdinfo->name = name;
 202         (*curmtd)->mtdinfo->size = length;
 203         (*curmtd)->mtdinfo->flags = MTD_CLEAR_BITS | MTD_SET_BITS |
 204                                         MTD_WRITEB_WRITEABLE | MTD_VOLATILE | 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
 214         if (add_mtd_device((*curmtd)->mtdinfo)) {
 215                 E("slram: Failed to register new device\n");
 216                 iounmap(((slram_priv_t *)(*curmtd)->mtdinfo->priv)->start);
 217                 kfree((*curmtd)->mtdinfo->priv);
 218                 kfree((*curmtd)->mtdinfo);
 219                 return(-EAGAIN);
 220         }
 221         T("slram: Registered device %s from %luKiB to %luKiB\n", name,
 222                         (start / 1024), ((start + length) / 1024));
 223         T("slram: Mapped from 0x%p to 0x%p\n",
 224                         ((slram_priv_t *)(*curmtd)->mtdinfo->priv)->start,
 225                         ((slram_priv_t *)(*curmtd)->mtdinfo->priv)->end);
 226         return(0);
 227 }
 228
 229 static void unregister_devices(void)
 230 {
 231         slram_mtd_list_t *nextitem;
 232
 233         while (slram_mtdlist) {
 234                 nextitem = slram_mtdlist->next;
 235                 del_mtd_device(slram_mtdlist->mtdinfo);
 236                 iounmap(((slram_priv_t *)slram_mtdlist->mtdinfo->priv)->start);
 237                 kfree(slram_mtdlist->mtdinfo->priv);
 238                 kfree(slram_mtdlist->mtdinfo);
 239                 kfree(slram_mtdlist);
 240                 slram_mtdlist = nextitem;
 241         }
 242 }
 243
 244 static unsigned long handle_unit(unsigned long value, char *unit)
 245 {
 246         if ((*unit == 'M') || (*unit == 'm')) {
 247                 return(value * 1024 * 1024);
 248         } else if ((*unit == 'K') || (*unit == 'k')) {
 249                 return(value * 1024);
 250         }
 251         return(value);
 252 }
 253
 254 static int parse_cmdline(char *devname, char *szstart, char *szlength)
 255 {
 256         char *buffer;
 257         unsigned long devstart;
 258         unsigned long devlength;
 259
 260         if ((!devname) || (!szstart) || (!szlength)) {
 261                 unregister_devices();
 262                 return(-EINVAL);
 263         }
 264
 265         devstart = simple_strtoul(szstart, &buffer, 0);
 266         devstart = handle_unit(devstart, buffer);
 267
 268         if (*(szlength) != '+') {
 269                 devlength = simple_strtoul(szlength, &buffer, 0);
 270                 devlength = handle_unit(devlength, buffer) - devstart;
 271         } else {
 272                 devlength = simple_strtoul(szlength + 1, &buffer, 0);
 273                 devlength = handle_unit(devlength, buffer);
 274         }
 275         T("slram: devname=%s, devstart=0x%lx, devlength=0x%lx\n",
 276                         devname, devstart, devlength);
 277         if ((devstart < 0) || (devlength < 0) || (devlength % SLRAM_BLK_SZ != 0)) {
 278                 E("slram: Illegal start / length parameter.\n");
 279                 return(-EINVAL);
 280         }
 281
 282         if ((devstart = register_device(devname, devstart, devlength))){
 283                 unregister_devices();
 284                 return((int)devstart);
 285         }
 286         return(0);
 287 }
 288
 289 #ifndef MODULE
 290
 291 static int __init mtd_slram_setup(char *str)
 292 {
 293         map = str;
 294         return(1);
 295 }
 296
 297 __setup("slram=", mtd_slram_setup);
 298
 299 #endif
 300
 301 static int init_slram(void)
 302 {
 303         char *devname;
 304         int i;
 305
 306 #ifndef MODULE
 307         char *devstart;
 308         char *devlength;
 309
 310         i = 0;
 311
 312         if (!map) {
 313                 E("slram: not enough parameters.\n");
 314                 return(-EINVAL);
 315         }
 316         while (map) {
 317                 devname = devstart = devlength = NULL;
 318
 319                 if (!(devname = strsep(&map, ","))) {
 320                         E("slram: No devicename specified.\n");
 321                         break;
 322                 }
 323                 T("slram: devname = %s\n", devname);
 324                 if ((!map) || (!(devstart = strsep(&map, ",")))) {
 325                         E("slram: No devicestart specified.\n");
 326                 }
 327                 T("slram: devstart = %s\n", devstart);
 328                 if ((!map) || (!(devlength = strsep(&map, ",")))) {
 329                         E("slram: No devicelength / -end specified.\n");
 330                 }
 331                 T("slram: devlength = %s\n", devlength);
 332                 if (parse_cmdline(devname, devstart, devlength) != 0) {
 333                         return(-EINVAL);
 334                 }
 335         }
 336 #else
 337         int count;
 338
 339         for (count = 0; (map[count]) && (count < SLRAM_MAX_DEVICES_PARAMS);
 340                         count++) {
 341         }
 342
 343         if ((count % 3 != 0) || (count == 0)) {
 344                 E("slram: not enough parameters.\n");
 345                 return(-EINVAL);
 346         }
 347         for (i = 0; i < (count / 3); i++) {
 348                 devname = map[i * 3];
 349
 350                 if (parse_cmdline(devname, map[i * 3 + 1], map[i * 3 + 2])!=0) {
 351                         return(-EINVAL);
 352                 }
 353
 354         }
 355 #endif /* !MODULE */
 356
 357         return(0);
 358 }
 359
 360 static void __exit cleanup_slram(void)
 361 {
 362         unregister_devices();
 363 }
 364
 365 module_init(init_slram);
 366 module_exit(cleanup_slram);
 367
 368 MODULE_LICENSE("GPL");
 369 MODULE_AUTHOR("Jochen Schaeuble <psionic@psionic.de>");
 370 MODULE_DESCRIPTION("MTD driver for uncached system RAM");