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