533 lines · c
1/*2 * block2mtd.c - create an mtd from a block device3 *4 * Copyright (C) 2001,2002 Simon Evans <spse@secret.org.uk>5 * Copyright (C) 2004-2006 Joern Engel <joern@wh.fh-wedel.de>6 *7 * Licence: GPL8 */9 10#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt11 12/*13 * When the first attempt at device initialization fails, we may need to14 * wait a little bit and retry. This timeout, by default 3 seconds, gives15 * device time to start up. Required on BCM2708 and a few other chipsets.16 */17#define MTD_DEFAULT_TIMEOUT 318 19#include <linux/module.h>20#include <linux/delay.h>21#include <linux/fs.h>22#include <linux/blkdev.h>23#include <linux/backing-dev.h>24#include <linux/bio.h>25#include <linux/pagemap.h>26#include <linux/list.h>27#include <linux/init.h>28#include <linux/mtd/mtd.h>29#include <linux/mutex.h>30#include <linux/mount.h>31#include <linux/slab.h>32#include <linux/major.h>33 34/* Maximum number of comma-separated items in the 'block2mtd=' parameter */35#define BLOCK2MTD_PARAM_MAX_COUNT 336 37/* Info for the block device */38struct block2mtd_dev {39 struct list_head list;40 struct file *bdev_file;41 struct mtd_info mtd;42 struct mutex write_mutex;43};44 45 46/* Static info about the MTD, used in cleanup_module */47static LIST_HEAD(blkmtd_device_list);48 49 50static struct page *page_read(struct address_space *mapping, pgoff_t index)51{52 return read_mapping_page(mapping, index, NULL);53}54 55/* erase a specified part of the device */56static int _block2mtd_erase(struct block2mtd_dev *dev, loff_t to, size_t len)57{58 struct address_space *mapping = dev->bdev_file->f_mapping;59 struct page *page;60 pgoff_t index = to >> PAGE_SHIFT; // page index61 int pages = len >> PAGE_SHIFT;62 u_long *p;63 u_long *max;64 65 while (pages) {66 page = page_read(mapping, index);67 if (IS_ERR(page))68 return PTR_ERR(page);69 70 max = page_address(page) + PAGE_SIZE;71 for (p=page_address(page); p<max; p++)72 if (*p != -1UL) {73 lock_page(page);74 memset(page_address(page), 0xff, PAGE_SIZE);75 set_page_dirty(page);76 unlock_page(page);77 balance_dirty_pages_ratelimited(mapping);78 break;79 }80 81 put_page(page);82 pages--;83 index++;84 }85 return 0;86}87static int block2mtd_erase(struct mtd_info *mtd, struct erase_info *instr)88{89 struct block2mtd_dev *dev = mtd->priv;90 size_t from = instr->addr;91 size_t len = instr->len;92 int err;93 94 mutex_lock(&dev->write_mutex);95 err = _block2mtd_erase(dev, from, len);96 mutex_unlock(&dev->write_mutex);97 if (err)98 pr_err("erase failed err = %d\n", err);99 100 return err;101}102 103 104static int block2mtd_read(struct mtd_info *mtd, loff_t from, size_t len,105 size_t *retlen, u_char *buf)106{107 struct block2mtd_dev *dev = mtd->priv;108 struct address_space *mapping = dev->bdev_file->f_mapping;109 struct page *page;110 pgoff_t index = from >> PAGE_SHIFT;111 int offset = from & (PAGE_SIZE-1);112 int cpylen;113 114 while (len) {115 if ((offset + len) > PAGE_SIZE)116 cpylen = PAGE_SIZE - offset; // multiple pages117 else118 cpylen = len; // this page119 len = len - cpylen;120 121 page = page_read(mapping, index);122 if (IS_ERR(page))123 return PTR_ERR(page);124 125 memcpy(buf, page_address(page) + offset, cpylen);126 put_page(page);127 128 if (retlen)129 *retlen += cpylen;130 buf += cpylen;131 offset = 0;132 index++;133 }134 return 0;135}136 137 138/* write data to the underlying device */139static int _block2mtd_write(struct block2mtd_dev *dev, const u_char *buf,140 loff_t to, size_t len, size_t *retlen)141{142 struct page *page;143 struct address_space *mapping = dev->bdev_file->f_mapping;144 pgoff_t index = to >> PAGE_SHIFT; // page index145 int offset = to & ~PAGE_MASK; // page offset146 int cpylen;147 148 while (len) {149 if ((offset+len) > PAGE_SIZE)150 cpylen = PAGE_SIZE - offset; // multiple pages151 else152 cpylen = len; // this page153 len = len - cpylen;154 155 page = page_read(mapping, index);156 if (IS_ERR(page))157 return PTR_ERR(page);158 159 if (memcmp(page_address(page)+offset, buf, cpylen)) {160 lock_page(page);161 memcpy(page_address(page) + offset, buf, cpylen);162 set_page_dirty(page);163 unlock_page(page);164 balance_dirty_pages_ratelimited(mapping);165 }166 put_page(page);167 168 if (retlen)169 *retlen += cpylen;170 171 buf += cpylen;172 offset = 0;173 index++;174 }175 return 0;176}177 178 179static int block2mtd_write(struct mtd_info *mtd, loff_t to, size_t len,180 size_t *retlen, const u_char *buf)181{182 struct block2mtd_dev *dev = mtd->priv;183 int err;184 185 mutex_lock(&dev->write_mutex);186 err = _block2mtd_write(dev, buf, to, len, retlen);187 mutex_unlock(&dev->write_mutex);188 if (err > 0)189 err = 0;190 return err;191}192 193 194/* sync the device - wait until the write queue is empty */195static void block2mtd_sync(struct mtd_info *mtd)196{197 struct block2mtd_dev *dev = mtd->priv;198 sync_blockdev(file_bdev(dev->bdev_file));199 return;200}201 202 203static void block2mtd_free_device(struct block2mtd_dev *dev)204{205 if (!dev)206 return;207 208 kfree(dev->mtd.name);209 210 if (dev->bdev_file) {211 invalidate_mapping_pages(dev->bdev_file->f_mapping, 0, -1);212 bdev_fput(dev->bdev_file);213 }214 215 kfree(dev);216}217 218/*219 * This function is marked __ref because it calls the __init marked220 * early_lookup_bdev when called from the early boot code.221 */222static struct file __ref *mdtblock_early_get_bdev(const char *devname,223 blk_mode_t mode, int timeout, struct block2mtd_dev *dev)224{225 struct file *bdev_file = ERR_PTR(-ENODEV);226#ifndef MODULE227 int i;228 229 /*230 * We can't use early_lookup_bdev from a running system.231 */232 if (system_state >= SYSTEM_RUNNING)233 return bdev_file;234 235 /*236 * We might not have the root device mounted at this point.237 * Try to resolve the device name by other means.238 */239 for (i = 0; i <= timeout; i++) {240 dev_t devt;241 242 if (i)243 /*244 * Calling wait_for_device_probe in the first loop245 * was not enough, sleep for a bit in subsequent246 * go-arounds.247 */248 msleep(1000);249 wait_for_device_probe();250 251 if (!early_lookup_bdev(devname, &devt)) {252 bdev_file = bdev_file_open_by_dev(devt, mode, dev, NULL);253 if (!IS_ERR(bdev_file))254 break;255 }256 }257#endif258 return bdev_file;259}260 261static struct block2mtd_dev *add_device(char *devname, int erase_size,262 char *label, int timeout)263{264 const blk_mode_t mode = BLK_OPEN_READ | BLK_OPEN_WRITE;265 struct file *bdev_file;266 struct block_device *bdev;267 struct block2mtd_dev *dev;268 loff_t size;269 char *name;270 271 if (!devname)272 return NULL;273 274 dev = kzalloc(sizeof(struct block2mtd_dev), GFP_KERNEL);275 if (!dev)276 return NULL;277 278 /* Get a handle on the device */279 bdev_file = bdev_file_open_by_path(devname, mode, dev, NULL);280 if (IS_ERR(bdev_file))281 bdev_file = mdtblock_early_get_bdev(devname, mode, timeout,282 dev);283 if (IS_ERR(bdev_file)) {284 pr_err("error: cannot open device %s\n", devname);285 goto err_free_block2mtd;286 }287 dev->bdev_file = bdev_file;288 bdev = file_bdev(bdev_file);289 290 if (MAJOR(bdev->bd_dev) == MTD_BLOCK_MAJOR) {291 pr_err("attempting to use an MTD device as a block device\n");292 goto err_free_block2mtd;293 }294 295 size = bdev_nr_bytes(bdev);296 if ((long)size % erase_size) {297 pr_err("erasesize must be a divisor of device size\n");298 goto err_free_block2mtd;299 }300 301 mutex_init(&dev->write_mutex);302 303 /* Setup the MTD structure */304 /* make the name contain the block device in */305 if (!label)306 name = kasprintf(GFP_KERNEL, "block2mtd: %s", devname);307 else308 name = kstrdup(label, GFP_KERNEL);309 if (!name)310 goto err_destroy_mutex;311 312 dev->mtd.name = name;313 314 dev->mtd.size = size & PAGE_MASK;315 dev->mtd.erasesize = erase_size;316 dev->mtd.writesize = 1;317 dev->mtd.writebufsize = PAGE_SIZE;318 dev->mtd.type = MTD_RAM;319 dev->mtd.flags = MTD_CAP_RAM;320 dev->mtd._erase = block2mtd_erase;321 dev->mtd._write = block2mtd_write;322 dev->mtd._sync = block2mtd_sync;323 dev->mtd._read = block2mtd_read;324 dev->mtd.priv = dev;325 dev->mtd.owner = THIS_MODULE;326 327 if (mtd_device_register(&dev->mtd, NULL, 0)) {328 /* Device didn't get added, so free the entry */329 goto err_destroy_mutex;330 }331 332 list_add(&dev->list, &blkmtd_device_list);333 pr_info("mtd%d: [%s] erase_size = %dKiB [%d]\n",334 dev->mtd.index,335 label ? label : dev->mtd.name + strlen("block2mtd: "),336 dev->mtd.erasesize >> 10, dev->mtd.erasesize);337 return dev;338 339err_destroy_mutex:340 mutex_destroy(&dev->write_mutex);341err_free_block2mtd:342 block2mtd_free_device(dev);343 return NULL;344}345 346 347/* This function works similar to reguler strtoul. In addition, it348 * allows some suffixes for a more human-readable number format:349 * ki, Ki, kiB, KiB - multiply result with 1024350 * Mi, MiB - multiply result with 1024^2351 * Gi, GiB - multiply result with 1024^3352 */353static int ustrtoul(const char *cp, char **endp, unsigned int base)354{355 unsigned long result = simple_strtoul(cp, endp, base);356 switch (**endp) {357 case 'G' :358 result *= 1024;359 fallthrough;360 case 'M':361 result *= 1024;362 fallthrough;363 case 'K':364 case 'k':365 result *= 1024;366 /* By dwmw2 editorial decree, "ki", "Mi" or "Gi" are to be used. */367 if ((*endp)[1] == 'i') {368 if ((*endp)[2] == 'B')369 (*endp) += 3;370 else371 (*endp) += 2;372 }373 }374 return result;375}376 377 378static int parse_num(size_t *num, const char *token)379{380 char *endp;381 size_t n;382 383 n = (size_t) ustrtoul(token, &endp, 0);384 if (*endp)385 return -EINVAL;386 387 *num = n;388 return 0;389}390 391 392static inline void kill_final_newline(char *str)393{394 char *newline = strrchr(str, '\n');395 if (newline && !newline[1])396 *newline = 0;397}398 399 400#ifndef MODULE401static int block2mtd_init_called = 0;402/* 80 for device, 12 for erase size */403static char block2mtd_paramline[80 + 12];404#endif405 406static int block2mtd_setup2(const char *val)407{408 /* 80 for device, 12 for erase size, 80 for name, 8 for timeout */409 char buf[80 + 12 + 80 + 8];410 char *str = buf;411 char *token[BLOCK2MTD_PARAM_MAX_COUNT];412 char *name;413 char *label = NULL;414 size_t erase_size = PAGE_SIZE;415 unsigned long timeout = MTD_DEFAULT_TIMEOUT;416 int i, ret;417 418 if (strnlen(val, sizeof(buf)) >= sizeof(buf)) {419 pr_err("parameter too long\n");420 return 0;421 }422 423 strcpy(str, val);424 kill_final_newline(str);425 426 for (i = 0; i < BLOCK2MTD_PARAM_MAX_COUNT; i++)427 token[i] = strsep(&str, ",");428 429 if (str) {430 pr_err("too many arguments\n");431 return 0;432 }433 434 if (!token[0]) {435 pr_err("no argument\n");436 return 0;437 }438 439 name = token[0];440 if (strlen(name) + 1 > 80) {441 pr_err("device name too long\n");442 return 0;443 }444 445 /* Optional argument when custom label is used */446 if (token[1] && strlen(token[1])) {447 ret = parse_num(&erase_size, token[1]);448 if (ret) {449 pr_err("illegal erase size\n");450 return 0;451 }452 }453 454 if (token[2]) {455 label = token[2];456 pr_info("Using custom MTD label '%s' for dev %s\n", label, name);457 }458 459 add_device(name, erase_size, label, timeout);460 461 return 0;462}463 464 465static int block2mtd_setup(const char *val, const struct kernel_param *kp)466{467#ifdef MODULE468 return block2mtd_setup2(val);469#else470 /* If more parameters are later passed in via471 /sys/module/block2mtd/parameters/block2mtd472 and block2mtd_init() has already been called,473 we can parse the argument now. */474 475 if (block2mtd_init_called)476 return block2mtd_setup2(val);477 478 /* During early boot stage, we only save the parameters479 here. We must parse them later: if the param passed480 from kernel boot command line, block2mtd_setup() is481 called so early that it is not possible to resolve482 the device (even kmalloc() fails). Deter that work to483 block2mtd_setup2(). */484 485 strscpy(block2mtd_paramline, val, sizeof(block2mtd_paramline));486 487 return 0;488#endif489}490 491 492module_param_call(block2mtd, block2mtd_setup, NULL, NULL, 0200);493MODULE_PARM_DESC(block2mtd, "Device to use. \"block2mtd=<dev>[,[<erasesize>][,<label>]]\"");494 495static int __init block2mtd_init(void)496{497 int ret = 0;498 499#ifndef MODULE500 if (strlen(block2mtd_paramline))501 ret = block2mtd_setup2(block2mtd_paramline);502 block2mtd_init_called = 1;503#endif504 505 return ret;506}507 508 509static void block2mtd_exit(void)510{511 struct list_head *pos, *next;512 513 /* Remove the MTD devices */514 list_for_each_safe(pos, next, &blkmtd_device_list) {515 struct block2mtd_dev *dev = list_entry(pos, typeof(*dev), list);516 block2mtd_sync(&dev->mtd);517 mtd_device_unregister(&dev->mtd);518 mutex_destroy(&dev->write_mutex);519 pr_info("mtd%d: [%s] removed\n",520 dev->mtd.index,521 dev->mtd.name + strlen("block2mtd: "));522 list_del(&dev->list);523 block2mtd_free_device(dev);524 }525}526 527late_initcall(block2mtd_init);528module_exit(block2mtd_exit);529 530MODULE_LICENSE("GPL");531MODULE_AUTHOR("Joern Engel <joern@lazybastard.org>");532MODULE_DESCRIPTION("Emulate an MTD using a block device");533