drivers/mtd/devices/phram.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /**
   3  * Copyright (c) ????           Jochen Schäuble <psionic@psionic.de>
   4  * Copyright (c) 2003-2004      Joern Engel <joern@wh.fh-wedel.de>
   5  *
   6  * Usage:
   7  *
   8  * one commend line parameter per device, each in the form:
   9  *   phram=<name>,<start>,<len>
  10  * <name> may be up to 63 characters.
  11  * <start> and <len> can be octal, decimal or hexadecimal.  If followed
  12  * by "ki", "Mi" or "Gi", the numbers will be interpreted as kilo, mega or
  13  * gigabytes.
  14  *
  15  * Example:
  16  *      phram=swap,64Mi,128Mi phram=test,900Mi,1Mi
  17  */
  18
  19 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  20
  21 #include <linux/io.h>
  22 #include <linux/init.h>
  23 #include <linux/kernel.h>
  24 #include <linux/list.h>
  25 #include <linux/module.h>
  26 #include <linux/moduleparam.h>
  27 #include <linux/slab.h>
  28 #include <linux/mtd/mtd.h>
  29
  30 struct phram_mtd_list {
  31         struct mtd_info mtd;
  32         struct list_head list;
  33 };
  34
  35 static LIST_HEAD(phram_list);
  36
  37 static int phram_erase(struct mtd_info *mtd, struct erase_info *instr)
  38 {
  39         u_char *start = mtd->priv;
  40
  41         memset(start + instr->addr, 0xff, instr->len);
  42
  43         return 0;
  44 }
  45
  46 static int phram_point(struct mtd_info *mtd, loff_t from, size_t len,
  47                 size_t *retlen, void **virt, resource_size_t *phys)
  48 {
  49         *virt = mtd->priv + from;
  50         *retlen = len;
  51         return 0;
  52 }
  53
  54 static int phram_unpoint(struct mtd_info *mtd, loff_t from, size_t len)
  55 {
  56         return 0;
  57 }
  58
  59 static int phram_read(struct mtd_info *mtd, loff_t from, size_t len,
  60                 size_t *retlen, u_char *buf)
  61 {
  62         u_char *start = mtd->priv;
  63
  64         memcpy(buf, start + from, len);
  65         *retlen = len;
  66         return 0;
  67 }
  68
  69 static int phram_write(struct mtd_info *mtd, loff_t to, size_t len,
  70                 size_t *retlen, const u_char *buf)
  71 {
  72         u_char *start = mtd->priv;
  73
  74         memcpy(start + to, buf, len);
  75         *retlen = len;
  76         return 0;
  77 }
  78
  79 static void unregister_devices(void)
  80 {
  81         struct phram_mtd_list *this, *safe;
  82
  83         list_for_each_entry_safe(this, safe, &phram_list, list) {
  84                 mtd_device_unregister(&this->mtd);
  85                 iounmap(this->mtd.priv);
  86                 kfree(this->mtd.name);
  87                 kfree(this);
  88         }
  89 }
  90
  91 static int register_device(char *name, phys_addr_t start, size_t len)
  92 {
  93         struct phram_mtd_list *new;
  94         int ret = -ENOMEM;
  95
  96         new = kzalloc(sizeof(*new), GFP_KERNEL);
  97         if (!new)
  98                 goto out0;
  99
 100         ret = -EIO;
 101         new->mtd.priv = ioremap(start, len);
 102         if (!new->mtd.priv) {
 103                 pr_err("ioremap failed\n");
 104                 goto out1;
 105         }
 106
 107
 108         new->mtd.name = name;
 109         new->mtd.size = len;
 110         new->mtd.flags = MTD_CAP_RAM;
 111         new->mtd._erase = phram_erase;
 112         new->mtd._point = phram_point;
 113         new->mtd._unpoint = phram_unpoint;
 114         new->mtd._read = phram_read;
 115         new->mtd._write = phram_write;
 116         new->mtd.owner = THIS_MODULE;
 117         new->mtd.type = MTD_RAM;
 118         new->mtd.erasesize = PAGE_SIZE;
 119         new->mtd.writesize = 1;
 120
 121         ret = -EAGAIN;
 122         if (mtd_device_register(&new->mtd, NULL, 0)) {
 123                 pr_err("Failed to register new device\n");
 124                 goto out2;
 125         }
 126
 127         list_add_tail(&new->list, &phram_list);
 128         return 0;
 129
 130 out2:
 131         iounmap(new->mtd.priv);
 132 out1:
 133         kfree(new);
 134 out0:
 135         return ret;
 136 }
 137
 138 static int parse_num64(uint64_t *num64, char *token)
 139 {
 140         size_t len;
 141         int shift = 0;
 142         int ret;
 143
 144         len = strlen(token);
 145         /* By dwmw2 editorial decree, "ki", "Mi" or "Gi" are to be used. */
 146         if (len > 2) {
 147                 if (token[len - 1] == 'i') {
 148                         switch (token[len - 2]) {
 149                         case 'G':
 150                                 shift += 10;
 151                                 /* fall through */
 152                         case 'M':
 153                                 shift += 10;
 154                                 /* fall through */
 155                         case 'k':
 156                                 shift += 10;
 157                                 token[len - 2] = 0;
 158                                 break;
 159                         default:
 160                                 return -EINVAL;
 161                         }
 162                 }
 163         }
 164
 165         ret = kstrtou64(token, 0, num64);
 166         *num64 <<= shift;
 167
 168         return ret;
 169 }
 170
 171 static int parse_name(char **pname, const char *token)
 172 {
 173         size_t len;
 174         char *name;
 175
 176         len = strlen(token) + 1;
 177         if (len > 64)
 178                 return -ENOSPC;
 179
 180         name = kstrdup(token, GFP_KERNEL);
 181         if (!name)
 182                 return -ENOMEM;
 183
 184         *pname = name;
 185         return 0;
 186 }
 187
 188
 189 static inline void kill_final_newline(char *str)
 190 {
 191         char *newline = strrchr(str, '\n');
 192
 193         if (newline && !newline[1])
 194                 *newline = 0;
 195 }
 196
 197
 198 #define parse_err(fmt, args...) do {    \
 199         pr_err(fmt , ## args);  \
 200         return 1;               \
 201 } while (0)
 202
 203 #ifndef MODULE
 204 static int phram_init_called;
 205 /*
 206  * This shall contain the module parameter if any. It is of the form:
 207  * - phram=<device>,<address>,<size> for module case
 208  * - phram.phram=<device>,<address>,<size> for built-in case
 209  * We leave 64 bytes for the device name, 20 for the address and 20 for the
 210  * size.
 211  * Example: phram.phram=rootfs,0xa0000000,512Mi
 212  */
 213 static char phram_paramline[64 + 20 + 20];
 214 #endif
 215
 216 static int phram_setup(const char *val)
 217 {
 218         char buf[64 + 20 + 20], *str = buf;
 219         char *token[3];
 220         char *name;
 221         uint64_t start;
 222         uint64_t len;
 223         int i, ret;
 224
 225         if (strnlen(val, sizeof(buf)) >= sizeof(buf))
 226                 parse_err("parameter too long\n");
 227
 228         strcpy(str, val);
 229         kill_final_newline(str);
 230
 231         for (i = 0; i < 3; i++)
 232                 token[i] = strsep(&str, ",");
 233
 234         if (str)
 235                 parse_err("too many arguments\n");
 236
 237         if (!token[2])
 238                 parse_err("not enough arguments\n");
 239
 240         ret = parse_name(&name, token[0]);
 241         if (ret)
 242                 return ret;
 243
 244         ret = parse_num64(&start, token[1]);
 245         if (ret) {
 246                 kfree(name);
 247                 parse_err("illegal start address\n");
 248         }
 249
 250         ret = parse_num64(&len, token[2]);
 251         if (ret) {
 252                 kfree(name);
 253                 parse_err("illegal device length\n");
 254         }
 255
 256         ret = register_device(name, start, len);
 257         if (!ret)
 258                 pr_info("%s device: %#llx at %#llx\n", name, len, start);
 259         else
 260                 kfree(name);
 261
 262         return ret;
 263 }
 264
 265 static int phram_param_call(const char *val, const struct kernel_param *kp)
 266 {
 267 #ifdef MODULE
 268         return phram_setup(val);
 269 #else
 270         /*
 271          * If more parameters are later passed in via
 272          * /sys/module/phram/parameters/phram
 273          * and init_phram() has already been called,
 274          * we can parse the argument now.
 275          */
 276
 277         if (phram_init_called)
 278                 return phram_setup(val);
 279
 280         /*
 281          * During early boot stage, we only save the parameters
 282          * here. We must parse them later: if the param passed
 283          * from kernel boot command line, phram_param_call() is
 284          * called so early that it is not possible to resolve
 285          * the device (even kmalloc() fails). Defer that work to
 286          * phram_setup().
 287          */
 288
 289         if (strlen(val) >= sizeof(phram_paramline))
 290                 return -ENOSPC;
 291         strcpy(phram_paramline, val);
 292
 293         return 0;
 294 #endif
 295 }
 296
 297 module_param_call(phram, phram_param_call, NULL, NULL, 000);
 298 MODULE_PARM_DESC(phram, "Memory region to map. \"phram=<name>,<start>,<length>\"");
 299
 300
 301 static int __init init_phram(void)
 302 {
 303         int ret = 0;
 304
 305 #ifndef MODULE
 306         if (phram_paramline[0])
 307                 ret = phram_setup(phram_paramline);
 308         phram_init_called = 1;
 309 #endif
 310
 311         return ret;
 312 }
 313
 314 static void __exit cleanup_phram(void)
 315 {
 316         unregister_devices();
 317 }
 318
 319 module_init(init_phram);
 320 module_exit(cleanup_phram);
 321
 322 MODULE_LICENSE("GPL");
 323 MODULE_AUTHOR("Joern Engel <joern@wh.fh-wedel.de>");
 324 MODULE_DESCRIPTION("MTD driver for physical RAM");