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 #include <linux/platform_device.h>
  31 #include <linux/of_address.h>
  32 #include <linux/of.h>
  33
  34 struct phram_mtd_list {
  35         struct mtd_info mtd;
  36         struct list_head list;
  37         bool cached;
  38 };
  39
  40 static LIST_HEAD(phram_list);
  41
  42 static int phram_erase(struct mtd_info *mtd, struct erase_info *instr)
  43 {
  44         u_char *start = mtd->priv;
  45
  46         memset(start + instr->addr, 0xff, instr->len);
  47
  48         return 0;
  49 }
  50
  51 static int phram_point(struct mtd_info *mtd, loff_t from, size_t len,
  52                 size_t *retlen, void **virt, resource_size_t *phys)
  53 {
  54         *virt = mtd->priv + from;
  55         *retlen = len;
  56         return 0;
  57 }
  58
  59 static int phram_unpoint(struct mtd_info *mtd, loff_t from, size_t len)
  60 {
  61         return 0;
  62 }
  63
  64 static int phram_read(struct mtd_info *mtd, loff_t from, size_t len,
  65                 size_t *retlen, u_char *buf)
  66 {
  67         u_char *start = mtd->priv;
  68
  69         memcpy(buf, start + from, len);
  70         *retlen = len;
  71         return 0;
  72 }
  73
  74 static int phram_write(struct mtd_info *mtd, loff_t to, size_t len,
  75                 size_t *retlen, const u_char *buf)
  76 {
  77         u_char *start = mtd->priv;
  78
  79         memcpy(start + to, buf, len);
  80         *retlen = len;
  81         return 0;
  82 }
  83
  84 static int phram_map(struct phram_mtd_list *phram, phys_addr_t start, size_t len)
  85 {
  86         void *addr = NULL;
  87
  88         if (phram->cached)
  89                 addr = memremap(start, len, MEMREMAP_WB);
  90         else
  91                 addr = (void __force *)ioremap(start, len);
  92         if (!addr)
  93                 return -EIO;
  94
  95         phram->mtd.priv = addr;
  96
  97         return 0;
  98 }
  99
 100 static void phram_unmap(struct phram_mtd_list *phram)
 101 {
 102         void *addr = phram->mtd.priv;
 103
 104         if (phram->cached) {
 105                 memunmap(addr);
 106                 return;
 107         }
 108
 109         iounmap((void __iomem *)addr);
 110 }
 111
 112 static void unregister_devices(void)
 113 {
 114         struct phram_mtd_list *this, *safe;
 115
 116         list_for_each_entry_safe(this, safe, &phram_list, list) {
 117                 mtd_device_unregister(&this->mtd);
 118                 phram_unmap(this);
 119                 kfree(this->mtd.name);
 120                 kfree(this);
 121         }
 122 }
 123
 124 static int register_device(struct platform_device *pdev, const char *name,
 125                            phys_addr_t start, size_t len, uint32_t erasesize)
 126 {
 127         struct device_node *np = pdev ? pdev->dev.of_node : NULL;
 128         bool cached = np ? !of_property_read_bool(np, "no-map") : false;
 129         struct phram_mtd_list *new;
 130         int ret = -ENOMEM;
 131
 132         new = kzalloc(sizeof(*new), GFP_KERNEL);
 133         if (!new)
 134                 goto out0;
 135
 136         new->cached = cached;
 137
 138         ret = phram_map(new, start, len);
 139         if (ret) {
 140                 pr_err("ioremap failed\n");
 141                 goto out1;
 142         }
 143
 144
 145         new->mtd.name = name;
 146         new->mtd.size = len;
 147         new->mtd.flags = MTD_CAP_RAM;
 148         new->mtd._erase = phram_erase;
 149         new->mtd._point = phram_point;
 150         new->mtd._unpoint = phram_unpoint;
 151         new->mtd._read = phram_read;
 152         new->mtd._write = phram_write;
 153         new->mtd.owner = THIS_MODULE;
 154         new->mtd.type = MTD_RAM;
 155         new->mtd.erasesize = erasesize;
 156         new->mtd.writesize = 1;
 157
 158         mtd_set_of_node(&new->mtd, np);
 159
 160         ret = -EAGAIN;
 161         if (mtd_device_register(&new->mtd, NULL, 0)) {
 162                 pr_err("Failed to register new device\n");
 163                 goto out2;
 164         }
 165
 166         if (pdev)
 167                 platform_set_drvdata(pdev, new);
 168         else
 169                 list_add_tail(&new->list, &phram_list);
 170
 171         return 0;
 172
 173 out2:
 174         phram_unmap(new);
 175 out1:
 176         kfree(new);
 177 out0:
 178         return ret;
 179 }
 180
 181 static int parse_num64(uint64_t *num64, char *token)
 182 {
 183         size_t len;
 184         int shift = 0;
 185         int ret;
 186
 187         len = strlen(token);
 188         /* By dwmw2 editorial decree, "ki", "Mi" or "Gi" are to be used. */
 189         if (len > 2) {
 190                 if (token[len - 1] == 'i') {
 191                         switch (token[len - 2]) {
 192                         case 'G':
 193                                 shift += 10;
 194                                 fallthrough;
 195                         case 'M':
 196                                 shift += 10;
 197                                 fallthrough;
 198                         case 'k':
 199                                 shift += 10;
 200                                 token[len - 2] = 0;
 201                                 break;
 202                         default:
 203                                 return -EINVAL;
 204                         }
 205                 }
 206         }
 207
 208         ret = kstrtou64(token, 0, num64);
 209         *num64 <<= shift;
 210
 211         return ret;
 212 }
 213
 214 static int parse_name(char **pname, const char *token)
 215 {
 216         size_t len;
 217         char *name;
 218
 219         len = strlen(token) + 1;
 220         if (len > 64)
 221                 return -ENOSPC;
 222
 223         name = kstrdup(token, GFP_KERNEL);
 224         if (!name)
 225                 return -ENOMEM;
 226
 227         *pname = name;
 228         return 0;
 229 }
 230
 231
 232 static inline void kill_final_newline(char *str)
 233 {
 234         char *newline = strrchr(str, '\n');
 235
 236         if (newline && !newline[1])
 237                 *newline = 0;
 238 }
 239
 240
 241 #define parse_err(fmt, args...) do {    \
 242         pr_err(fmt , ## args);  \
 243         return 1;               \
 244 } while (0)
 245
 246 #ifndef MODULE
 247 static int phram_init_called;
 248 /*
 249  * This shall contain the module parameter if any. It is of the form:
 250  * - phram=<device>,<address>,<size>[,<erasesize>] for module case
 251  * - phram.phram=<device>,<address>,<size>[,<erasesize>] for built-in case
 252  * We leave 64 bytes for the device name, 20 for the address , 20 for the
 253  * size and 20 for the erasesize.
 254  * Example: phram.phram=rootfs,0xa0000000,512Mi,65536
 255  */
 256 static char phram_paramline[64 + 20 + 20 + 20];
 257 #endif
 258
 259 static int phram_setup(const char *val)
 260 {
 261         char buf[64 + 20 + 20 + 20], *str = buf;
 262         char *token[4];
 263         char *name;
 264         uint64_t start;
 265         uint64_t len;
 266         uint64_t erasesize = PAGE_SIZE;
 267         uint32_t rem;
 268         int i, ret;
 269
 270         if (strnlen(val, sizeof(buf)) >= sizeof(buf))
 271                 parse_err("parameter too long\n");
 272
 273         strcpy(str, val);
 274         kill_final_newline(str);
 275
 276         for (i = 0; i < 4; i++)
 277                 token[i] = strsep(&str, ",");
 278
 279         if (str)
 280                 parse_err("too many arguments\n");
 281
 282         if (!token[2])
 283                 parse_err("not enough arguments\n");
 284
 285         ret = parse_name(&name, token[0]);
 286         if (ret)
 287                 return ret;
 288
 289         ret = parse_num64(&start, token[1]);
 290         if (ret) {
 291                 parse_err("illegal start address\n");
 292                 goto error;
 293         }
 294
 295         ret = parse_num64(&len, token[2]);
 296         if (ret) {
 297                 parse_err("illegal device length\n");
 298                 goto error;
 299         }
 300
 301         if (token[3]) {
 302                 ret = parse_num64(&erasesize, token[3]);
 303                 if (ret) {
 304                         parse_err("illegal erasesize\n");
 305                         goto error;
 306                 }
 307         }
 308
 309         if (len == 0 || erasesize == 0 || erasesize > len
 310             || erasesize > UINT_MAX) {
 311                 parse_err("illegal erasesize or len\n");
 312                 ret = -EINVAL;
 313                 goto error;
 314         }
 315
 316         div_u64_rem(len, (uint32_t)erasesize, &rem);
 317         if (rem) {
 318                 parse_err("len is not multiple of erasesize\n");
 319                 ret = -EINVAL;
 320                 goto error;
 321         }
 322
 323         ret = register_device(NULL, name, start, len, (uint32_t)erasesize);
 324         if (ret)
 325                 goto error;
 326
 327         pr_info("%s device: %#llx at %#llx for erasesize %#llx\n", name, len, start, erasesize);
 328         return 0;
 329
 330 error:
 331         kfree(name);
 332         return ret;
 333 }
 334
 335 static int phram_param_call(const char *val, const struct kernel_param *kp)
 336 {
 337 #ifdef MODULE
 338         return phram_setup(val);
 339 #else
 340         /*
 341          * If more parameters are later passed in via
 342          * /sys/module/phram/parameters/phram
 343          * and init_phram() has already been called,
 344          * we can parse the argument now.
 345          */
 346
 347         if (phram_init_called)
 348                 return phram_setup(val);
 349
 350         /*
 351          * During early boot stage, we only save the parameters
 352          * here. We must parse them later: if the param passed
 353          * from kernel boot command line, phram_param_call() is
 354          * called so early that it is not possible to resolve
 355          * the device (even kmalloc() fails). Defer that work to
 356          * phram_setup().
 357          */
 358
 359         if (strlen(val) >= sizeof(phram_paramline))
 360                 return -ENOSPC;
 361         strcpy(phram_paramline, val);
 362
 363         return 0;
 364 #endif
 365 }
 366
 367 module_param_call(phram, phram_param_call, NULL, NULL, 0200);
 368 MODULE_PARM_DESC(phram, "Memory region to map. \"phram=<name>,<start>,<length>[,<erasesize>]\"");
 369
 370 #ifdef CONFIG_OF
 371 static const struct of_device_id phram_of_match[] = {
 372         { .compatible = "phram" },
 373         {}
 374 };
 375 MODULE_DEVICE_TABLE(of, phram_of_match);
 376 #endif
 377
 378 static int phram_probe(struct platform_device *pdev)
 379 {
 380         struct resource *res;
 381
 382         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 383         if (!res)
 384                 return -ENOMEM;
 385
 386         /* mtd_set_of_node() reads name from "label" */
 387         return register_device(pdev, NULL, res->start, resource_size(res),
 388                                PAGE_SIZE);
 389 }
 390
 391 static int phram_remove(struct platform_device *pdev)
 392 {
 393         struct phram_mtd_list *phram = platform_get_drvdata(pdev);
 394
 395         mtd_device_unregister(&phram->mtd);
 396         phram_unmap(phram);
 397         kfree(phram);
 398
 399         return 0;
 400 }
 401
 402 static struct platform_driver phram_driver = {
 403         .probe          = phram_probe,
 404         .remove         = phram_remove,
 405         .driver         = {
 406                 .name           = "phram",
 407                 .of_match_table = of_match_ptr(phram_of_match),
 408         },
 409 };
 410
 411 static int __init init_phram(void)
 412 {
 413         int ret;
 414
 415         ret = platform_driver_register(&phram_driver);
 416         if (ret)
 417                 return ret;
 418
 419 #ifndef MODULE
 420         if (phram_paramline[0])
 421                 ret = phram_setup(phram_paramline);
 422         phram_init_called = 1;
 423 #endif
 424
 425         if (ret)
 426                 platform_driver_unregister(&phram_driver);
 427
 428         return ret;
 429 }
 430
 431 static void __exit cleanup_phram(void)
 432 {
 433         unregister_devices();
 434         platform_driver_unregister(&phram_driver);
 435 }
 436
 437 module_init(init_phram);
 438 module_exit(cleanup_phram);
 439
 440 MODULE_LICENSE("GPL");
 441 MODULE_AUTHOR("Joern Engel <joern@wh.fh-wedel.de>");
 442 MODULE_DESCRIPTION("MTD driver for physical RAM");