drivers/mtd/devices/phram.c

   1 /**
   2  * Copyright (c) ????           Jochen Schäuble <psionic@psionic.de>
   3  * Copyright (c) 2003-2004      Joern Engel <joern@wh.fh-wedel.de>
   4  *
   5  * Usage:
   6  *
   7  * one commend line parameter per device, each in the form:
   8  *   phram=<name>,<start>,<len>
   9  * <name> may be up to 63 characters.
  10  * <start> and <len> can be octal, decimal or hexadecimal.  If followed
  11  * by "ki", "Mi" or "Gi", the numbers will be interpreted as kilo, mega or
  12  * gigabytes.
  13  *
  14  * Example:
  15  *      phram=swap,64Mi,128Mi phram=test,900Mi,1Mi
  16  */
  17
  18 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  19
  20 #include <linux/io.h>
  21 #include <linux/init.h>
  22 #include <linux/kernel.h>
  23 #include <linux/list.h>
  24 #include <linux/module.h>
  25 #include <linux/moduleparam.h>
  26 #include <linux/slab.h>
  27 #include <linux/mtd/mtd.h>
  28
  29 struct phram_mtd_list {
  30         struct mtd_info mtd;
  31         struct list_head list;
  32 };
  33
  34 static LIST_HEAD(phram_list);
  35
  36 static int phram_erase(struct mtd_info *mtd, struct erase_info *instr)
  37 {
  38         u_char *start = mtd->priv;
  39
  40         memset(start + instr->addr, 0xff, instr->len);
  41
  42         /*
  43          * This'll catch a few races. Free the thing before returning :)
  44          * I don't feel at all ashamed. This kind of thing is possible anyway
  45          * with flash, but unlikely.
  46          */
  47         instr->state = MTD_ERASE_DONE;
  48         mtd_erase_callback(instr);
  49         return 0;
  50 }
  51
  52 static int phram_point(struct mtd_info *mtd, loff_t from, size_t len,
  53                 size_t *retlen, void **virt, resource_size_t *phys)
  54 {
  55         *virt = mtd->priv + from;
  56         *retlen = len;
  57         return 0;
  58 }
  59
  60 static int phram_unpoint(struct mtd_info *mtd, loff_t from, size_t len)
  61 {
  62         return 0;
  63 }
  64
  65 static int phram_read(struct mtd_info *mtd, loff_t from, size_t len,
  66                 size_t *retlen, u_char *buf)
  67 {
  68         u_char *start = mtd->priv;
  69
  70         memcpy(buf, start + from, len);
  71         *retlen = len;
  72         return 0;
  73 }
  74
  75 static int phram_write(struct mtd_info *mtd, loff_t to, size_t len,
  76                 size_t *retlen, const u_char *buf)
  77 {
  78         u_char *start = mtd->priv;
  79
  80         memcpy(start + to, buf, len);
  81         *retlen = len;
  82         return 0;
  83 }
  84
  85 static void unregister_devices(void)
  86 {
  87         struct phram_mtd_list *this, *safe;
  88
  89         list_for_each_entry_safe(this, safe, &phram_list, list) {
  90                 mtd_device_unregister(&this->mtd);
  91                 iounmap(this->mtd.priv);
  92                 kfree(this->mtd.name);
  93                 kfree(this);
  94         }
  95 }
  96
  97 static int register_device(char *name, phys_addr_t start, size_t len)
  98 {
  99         struct phram_mtd_list *new;
 100         int ret = -ENOMEM;
 101
 102         new = kzalloc(sizeof(*new), GFP_KERNEL);
 103         if (!new)
 104                 goto out0;
 105
 106         ret = -EIO;
 107         new->mtd.priv = ioremap(start, len);
 108         if (!new->mtd.priv) {
 109                 pr_err("ioremap failed\n");
 110                 goto out1;
 111         }
 112
 113
 114         new->mtd.name = name;
 115         new->mtd.size = len;
 116         new->mtd.flags = MTD_CAP_RAM;
 117         new->mtd._erase = phram_erase;
 118         new->mtd._point = phram_point;
 119         new->mtd._unpoint = phram_unpoint;
 120         new->mtd._read = phram_read;
 121         new->mtd._write = phram_write;
 122         new->mtd.owner = THIS_MODULE;
 123         new->mtd.type = MTD_RAM;
 124         new->mtd.erasesize = PAGE_SIZE;
 125         new->mtd.writesize = 1;
 126
 127         ret = -EAGAIN;
 128         if (mtd_device_register(&new->mtd, NULL, 0)) {
 129                 pr_err("Failed to register new device\n");
 130                 goto out2;
 131         }
 132
 133         list_add_tail(&new->list, &phram_list);
 134         return 0;
 135
 136 out2:
 137         iounmap(new->mtd.priv);
 138 out1:
 139         kfree(new);
 140 out0:
 141         return ret;
 142 }
 143
 144 static int parse_num64(uint64_t *num64, char *token)
 145 {
 146         size_t len;
 147         int shift = 0;
 148         int ret;
 149
 150         len = strlen(token);
 151         /* By dwmw2 editorial decree, "ki", "Mi" or "Gi" are to be used. */
 152         if (len > 2) {
 153                 if (token[len - 1] == 'i') {
 154                         switch (token[len - 2]) {
 155                         case 'G':
 156                                 shift += 10;
 157                         case 'M':
 158                                 shift += 10;
 159                         case 'k':
 160                                 shift += 10;
 161                                 token[len - 2] = 0;
 162                                 break;
 163                         default:
 164                                 return -EINVAL;
 165                         }
 166                 }
 167         }
 168
 169         ret = kstrtou64(token, 0, num64);
 170         *num64 <<= shift;
 171
 172         return ret;
 173 }
 174
 175 static int parse_name(char **pname, const char *token)
 176 {
 177         size_t len;
 178         char *name;
 179
 180         len = strlen(token) + 1;
 181         if (len > 64)
 182                 return -ENOSPC;
 183
 184         name = kstrdup(token, GFP_KERNEL);
 185         if (!name)
 186                 return -ENOMEM;
 187
 188         *pname = name;
 189         return 0;
 190 }
 191
 192
 193 static inline void kill_final_newline(char *str)
 194 {
 195         char *newline = strrchr(str, '\n');
 196
 197         if (newline && !newline[1])
 198                 *newline = 0;
 199 }
 200
 201
 202 #define parse_err(fmt, args...) do {    \
 203         pr_err(fmt , ## args);  \
 204         return 1;               \
 205 } while (0)
 206
 207 #ifndef MODULE
 208 static int phram_init_called;
 209 /*
 210  * This shall contain the module parameter if any. It is of the form:
 211  * - phram=<device>,<address>,<size> for module case
 212  * - phram.phram=<device>,<address>,<size> for built-in case
 213  * We leave 64 bytes for the device name, 20 for the address and 20 for the
 214  * size.
 215  * Example: phram.phram=rootfs,0xa0000000,512Mi
 216  */
 217 static char phram_paramline[64 + 20 + 20];
 218 #endif
 219
 220 static int phram_setup(const char *val)
 221 {
 222         char buf[64 + 20 + 20], *str = buf;
 223         char *token[3];
 224         char *name;
 225         uint64_t start;
 226         uint64_t len;
 227         int i, ret;
 228
 229         if (strnlen(val, sizeof(buf)) >= sizeof(buf))
 230                 parse_err("parameter too long\n");
 231
 232         strcpy(str, val);
 233         kill_final_newline(str);
 234
 235         for (i = 0; i < 3; i++)
 236                 token[i] = strsep(&str, ",");
 237
 238         if (str)
 239                 parse_err("too many arguments\n");
 240
 241         if (!token[2])
 242                 parse_err("not enough arguments\n");
 243
 244         ret = parse_name(&name, token[0]);
 245         if (ret)
 246                 return ret;
 247
 248         ret = parse_num64(&start, token[1]);
 249         if (ret) {
 250                 kfree(name);
 251                 parse_err("illegal start address\n");
 252         }
 253
 254         ret = parse_num64(&len, token[2]);
 255         if (ret) {
 256                 kfree(name);
 257                 parse_err("illegal device length\n");
 258         }
 259
 260         ret = register_device(name, start, len);
 261         if (!ret)
 262                 pr_info("%s device: %#llx at %#llx\n", name, len, start);
 263         else
 264                 kfree(name);
 265
 266         return ret;
 267 }
 268
 269 static int phram_param_call(const char *val, const struct kernel_param *kp)
 270 {
 271 #ifdef MODULE
 272         return phram_setup(val);
 273 #else
 274         /*
 275          * If more parameters are later passed in via
 276          * /sys/module/phram/parameters/phram
 277          * and init_phram() has already been called,
 278          * we can parse the argument now.
 279          */
 280
 281         if (phram_init_called)
 282                 return phram_setup(val);
 283
 284         /*
 285          * During early boot stage, we only save the parameters
 286          * here. We must parse them later: if the param passed
 287          * from kernel boot command line, phram_param_call() is
 288          * called so early that it is not possible to resolve
 289          * the device (even kmalloc() fails). Defer that work to
 290          * phram_setup().
 291          */
 292
 293         if (strlen(val) >= sizeof(phram_paramline))
 294                 return -ENOSPC;
 295         strcpy(phram_paramline, val);
 296
 297         return 0;
 298 #endif
 299 }
 300
 301 module_param_call(phram, phram_param_call, NULL, NULL, 000);
 302 MODULE_PARM_DESC(phram, "Memory region to map. \"phram=<name>,<start>,<length>\"");
 303
 304
 305 static int __init init_phram(void)
 306 {
 307         int ret = 0;
 308
 309 #ifndef MODULE
 310         if (phram_paramline[0])
 311                 ret = phram_setup(phram_paramline);
 312         phram_init_called = 1;
 313 #endif
 314
 315         return ret;
 316 }
 317
 318 static void __exit cleanup_phram(void)
 319 {
 320         unregister_devices();
 321 }
 322
 323 module_init(init_phram);
 324 module_exit(cleanup_phram);
 325
 326 MODULE_LICENSE("GPL");
 327 MODULE_AUTHOR("Joern Engel <joern@wh.fh-wedel.de>");
 328 MODULE_DESCRIPTION("MTD driver for physical RAM");