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>[,<erasesize>]
  10  * <name> may be up to 63 characters.
  11  * <start>, <len>, and <erasesize> 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. <erasesize> is optional and defaults to PAGE_SIZE.
  14  *
  15  * Example:
  16  *      phram=swap,64Mi,128Mi phram=test,900Mi,1Mi,64Ki
  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 #include <asm/div64.h>
  30
  31 struct phram_mtd_list {
  32         struct mtd_info mtd;
  33         struct list_head list;
  34 };
  35
  36 static LIST_HEAD(phram_list);
  37
  38 static int phram_erase(struct mtd_info *mtd, struct erase_info *instr)
  39 {
  40         u_char *start = mtd->priv;
  41
  42         memset(start + instr->addr, 0xff, instr->len);
  43
  44         return 0;
  45 }
  46
  47 static int phram_point(struct mtd_info *mtd, loff_t from, size_t len,
  48                 size_t *retlen, void **virt, resource_size_t *phys)
  49 {
  50         *virt = mtd->priv + from;
  51         *retlen = len;
  52         return 0;
  53 }
  54
  55 static int phram_unpoint(struct mtd_info *mtd, loff_t from, size_t len)
  56 {
  57         return 0;
  58 }
  59
  60 static int phram_read(struct mtd_info *mtd, loff_t from, size_t len,
  61                 size_t *retlen, u_char *buf)
  62 {
  63         u_char *start = mtd->priv;
  64
  65         memcpy(buf, start + from, len);
  66         *retlen = len;
  67         return 0;
  68 }
  69
  70 static int phram_write(struct mtd_info *mtd, loff_t to, size_t len,
  71                 size_t *retlen, const u_char *buf)
  72 {
  73         u_char *start = mtd->priv;
  74
  75         memcpy(start + to, buf, len);
  76         *retlen = len;
  77         return 0;
  78 }
  79
  80 static void unregister_devices(void)
  81 {
  82         struct phram_mtd_list *this, *safe;
  83
  84         list_for_each_entry_safe(this, safe, &phram_list, list) {
  85                 mtd_device_unregister(&this->mtd);
  86                 iounmap(this->mtd.priv);
  87                 kfree(this->mtd.name);
  88                 kfree(this);
  89         }
  90 }
  91
  92 static int register_device(char *name, phys_addr_t start, size_t len, uint32_t erasesize)
  93 {
  94         struct phram_mtd_list *new;
  95         int ret = -ENOMEM;
  96
  97         new = kzalloc(sizeof(*new), GFP_KERNEL);
  98         if (!new)
  99                 goto out0;
 100
 101         ret = -EIO;
 102         new->mtd.priv = ioremap(start, len);
 103         if (!new->mtd.priv) {
 104                 pr_err("ioremap failed\n");
 105                 goto out1;
 106         }
 107
 108
 109         new->mtd.name = name;
 110         new->mtd.size = len;
 111         new->mtd.flags = MTD_CAP_RAM;
 112         new->mtd._erase = phram_erase;
 113         new->mtd._point = phram_point;
 114         new->mtd._unpoint = phram_unpoint;
 115         new->mtd._read = phram_read;
 116         new->mtd._write = phram_write;
 117         new->mtd.owner = THIS_MODULE;
 118         new->mtd.type = MTD_RAM;
 119         new->mtd.erasesize = erasesize;
 120         new->mtd.writesize = 1;
 121
 122         ret = -EAGAIN;
 123         if (mtd_device_register(&new->mtd, NULL, 0)) {
 124                 pr_err("Failed to register new device\n");
 125                 goto out2;
 126         }
 127
 128         list_add_tail(&new->list, &phram_list);
 129         return 0;
 130
 131 out2:
 132         iounmap(new->mtd.priv);
 133 out1:
 134         kfree(new);
 135 out0:
 136         return ret;
 137 }
 138
 139 static int parse_num64(uint64_t *num64, char *token)
 140 {
 141         size_t len;
 142         int shift = 0;
 143         int ret;
 144
 145         len = strlen(token);
 146         /* By dwmw2 editorial decree, "ki", "Mi" or "Gi" are to be used. */
 147         if (len > 2) {
 148                 if (token[len - 1] == 'i') {
 149                         switch (token[len - 2]) {
 150                         case 'G':
 151                                 shift += 10;
 152                                 fallthrough;
 153                         case 'M':
 154                                 shift += 10;
 155                                 fallthrough;
 156                         case 'k':
 157                                 shift += 10;
 158                                 token[len - 2] = 0;
 159                                 break;
 160                         default:
 161                                 return -EINVAL;
 162                         }
 163                 }
 164         }
 165
 166         ret = kstrtou64(token, 0, num64);
 167         *num64 <<= shift;
 168
 169         return ret;
 170 }
 171
 172 static int parse_name(char **pname, const char *token)
 173 {
 174         size_t len;
 175         char *name;
 176
 177         len = strlen(token) + 1;
 178         if (len > 64)
 179                 return -ENOSPC;
 180
 181         name = kstrdup(token, GFP_KERNEL);
 182         if (!name)
 183                 return -ENOMEM;
 184
 185         *pname = name;
 186         return 0;
 187 }
 188
 189
 190 static inline void kill_final_newline(char *str)
 191 {
 192         char *newline = strrchr(str, '\n');
 193
 194         if (newline && !newline[1])
 195                 *newline = 0;
 196 }
 197
 198
 199 #define parse_err(fmt, args...) do {    \
 200         pr_err(fmt , ## args);  \
 201         return 1;               \
 202 } while (0)
 203
 204 #ifndef MODULE
 205 static int phram_init_called;
 206 /*
 207  * This shall contain the module parameter if any. It is of the form:
 208  * - phram=<device>,<address>,<size>[,<erasesize>] for module case
 209  * - phram.phram=<device>,<address>,<size>[,<erasesize>] for built-in case
 210  * We leave 64 bytes for the device name, 20 for the address , 20 for the
 211  * size and 20 for the erasesize.
 212  * Example: phram.phram=rootfs,0xa0000000,512Mi,65536
 213  */
 214 static char phram_paramline[64 + 20 + 20 + 20];
 215 #endif
 216
 217 static int phram_setup(const char *val)
 218 {
 219         char buf[64 + 20 + 20 + 20], *str = buf;
 220         char *token[4];
 221         char *name;
 222         uint64_t start;
 223         uint64_t len;
 224         uint64_t erasesize = PAGE_SIZE;
 225         int i, ret;
 226
 227         if (strnlen(val, sizeof(buf)) >= sizeof(buf))
 228                 parse_err("parameter too long\n");
 229
 230         strcpy(str, val);
 231         kill_final_newline(str);
 232
 233         for (i = 0; i < 4; i++)
 234                 token[i] = strsep(&str, ",");
 235
 236         if (str)
 237                 parse_err("too many arguments\n");
 238
 239         if (!token[2])
 240                 parse_err("not enough arguments\n");
 241
 242         ret = parse_name(&name, token[0]);
 243         if (ret)
 244                 return ret;
 245
 246         ret = parse_num64(&start, token[1]);
 247         if (ret) {
 248                 parse_err("illegal start address\n");
 249                 goto error;
 250         }
 251
 252         ret = parse_num64(&len, token[2]);
 253         if (ret) {
 254                 parse_err("illegal device length\n");
 255                 goto error;
 256         }
 257
 258         if (token[3]) {
 259                 ret = parse_num64(&erasesize, token[3]);
 260                 if (ret) {
 261                         parse_err("illegal erasesize\n");
 262                         goto error;
 263                 }
 264         }
 265
 266         if (len == 0 || erasesize == 0 || erasesize > len
 267             || erasesize > UINT_MAX || do_div(len, (uint32_t)erasesize) != 0) {
 268                 parse_err("illegal erasesize or len\n");
 269                 goto error;
 270         }
 271
 272         ret = register_device(name, start, len, (uint32_t)erasesize);
 273         if (ret)
 274                 goto error;
 275
 276         pr_info("%s device: %#llx at %#llx for erasesize %#llx\n", name, len, start, erasesize);
 277         return 0;
 278
 279 error:
 280         kfree(name);
 281         return ret;
 282 }
 283
 284 static int phram_param_call(const char *val, const struct kernel_param *kp)
 285 {
 286 #ifdef MODULE
 287         return phram_setup(val);
 288 #else
 289         /*
 290          * If more parameters are later passed in via
 291          * /sys/module/phram/parameters/phram
 292          * and init_phram() has already been called,
 293          * we can parse the argument now.
 294          */
 295
 296         if (phram_init_called)
 297                 return phram_setup(val);
 298
 299         /*
 300          * During early boot stage, we only save the parameters
 301          * here. We must parse them later: if the param passed
 302          * from kernel boot command line, phram_param_call() is
 303          * called so early that it is not possible to resolve
 304          * the device (even kmalloc() fails). Defer that work to
 305          * phram_setup().
 306          */
 307
 308         if (strlen(val) >= sizeof(phram_paramline))
 309                 return -ENOSPC;
 310         strcpy(phram_paramline, val);
 311
 312         return 0;
 313 #endif
 314 }
 315
 316 module_param_call(phram, phram_param_call, NULL, NULL, 0200);
 317 MODULE_PARM_DESC(phram, "Memory region to map. \"phram=<name>,<start>,<length>[,<erasesize>]\"");
 318
 319
 320 static int __init init_phram(void)
 321 {
 322         int ret = 0;
 323
 324 #ifndef MODULE
 325         if (phram_paramline[0])
 326                 ret = phram_setup(phram_paramline);
 327         phram_init_called = 1;
 328 #endif
 329
 330         return ret;
 331 }
 332
 333 static void __exit cleanup_phram(void)
 334 {
 335         unregister_devices();
 336 }
 337
 338 module_init(init_phram);
 339 module_exit(cleanup_phram);
 340
 341 MODULE_LICENSE("GPL");
 342 MODULE_AUTHOR("Joern Engel <joern@wh.fh-wedel.de>");
 343 MODULE_DESCRIPTION("MTD driver for physical RAM");