diff options
Diffstat (limited to 'kernel/drivers/mtd/devices/block2mtd.c')
| -rw-r--r-- | kernel/drivers/mtd/devices/block2mtd.c | 500 |
1 files changed, 500 insertions, 0 deletions
diff --git a/kernel/drivers/mtd/devices/block2mtd.c b/kernel/drivers/mtd/devices/block2mtd.c new file mode 100644 index 000000000..b16f3cda9 --- /dev/null +++ b/kernel/drivers/mtd/devices/block2mtd.c @@ -0,0 +1,500 @@ +/* + * block2mtd.c - create an mtd from a block device + * + * Copyright (C) 2001,2002 Simon Evans <spse@secret.org.uk> + * Copyright (C) 2004-2006 Joern Engel <joern@wh.fh-wedel.de> + * + * Licence: GPL + */ + +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt + +/* + * When the first attempt at device initialization fails, we may need to + * wait a little bit and retry. This timeout, by default 3 seconds, gives + * device time to start up. Required on BCM2708 and a few other chipsets. + */ +#define MTD_DEFAULT_TIMEOUT 3 + +#include <linux/module.h> +#include <linux/delay.h> +#include <linux/fs.h> +#include <linux/blkdev.h> +#include <linux/bio.h> +#include <linux/pagemap.h> +#include <linux/list.h> +#include <linux/init.h> +#include <linux/mtd/mtd.h> +#include <linux/mutex.h> +#include <linux/mount.h> +#include <linux/slab.h> +#include <linux/major.h> + +/* Info for the block device */ +struct block2mtd_dev { + struct list_head list; + struct block_device *blkdev; + struct mtd_info mtd; + struct mutex write_mutex; +}; + + +/* Static info about the MTD, used in cleanup_module */ +static LIST_HEAD(blkmtd_device_list); + + +static struct page *page_read(struct address_space *mapping, int index) +{ + return read_mapping_page(mapping, index, NULL); +} + +/* erase a specified part of the device */ +static int _block2mtd_erase(struct block2mtd_dev *dev, loff_t to, size_t len) +{ + struct address_space *mapping = dev->blkdev->bd_inode->i_mapping; + struct page *page; + int index = to >> PAGE_SHIFT; // page index + int pages = len >> PAGE_SHIFT; + u_long *p; + u_long *max; + + while (pages) { + page = page_read(mapping, index); + if (IS_ERR(page)) + return PTR_ERR(page); + + max = page_address(page) + PAGE_SIZE; + for (p=page_address(page); p<max; p++) + if (*p != -1UL) { + lock_page(page); + memset(page_address(page), 0xff, PAGE_SIZE); + set_page_dirty(page); + unlock_page(page); + balance_dirty_pages_ratelimited(mapping); + break; + } + + page_cache_release(page); + pages--; + index++; + } + return 0; +} +static int block2mtd_erase(struct mtd_info *mtd, struct erase_info *instr) +{ + struct block2mtd_dev *dev = mtd->priv; + size_t from = instr->addr; + size_t len = instr->len; + int err; + + instr->state = MTD_ERASING; + mutex_lock(&dev->write_mutex); + err = _block2mtd_erase(dev, from, len); + mutex_unlock(&dev->write_mutex); + if (err) { + pr_err("erase failed err = %d\n", err); + instr->state = MTD_ERASE_FAILED; + } else + instr->state = MTD_ERASE_DONE; + + mtd_erase_callback(instr); + return err; +} + + +static int block2mtd_read(struct mtd_info *mtd, loff_t from, size_t len, + size_t *retlen, u_char *buf) +{ + struct block2mtd_dev *dev = mtd->priv; + struct page *page; + int index = from >> PAGE_SHIFT; + int offset = from & (PAGE_SIZE-1); + int cpylen; + + while (len) { + if ((offset + len) > PAGE_SIZE) + cpylen = PAGE_SIZE - offset; // multiple pages + else + cpylen = len; // this page + len = len - cpylen; + + page = page_read(dev->blkdev->bd_inode->i_mapping, index); + if (IS_ERR(page)) + return PTR_ERR(page); + + memcpy(buf, page_address(page) + offset, cpylen); + page_cache_release(page); + + if (retlen) + *retlen += cpylen; + buf += cpylen; + offset = 0; + index++; + } + return 0; +} + + +/* write data to the underlying device */ +static int _block2mtd_write(struct block2mtd_dev *dev, const u_char *buf, + loff_t to, size_t len, size_t *retlen) +{ + struct page *page; + struct address_space *mapping = dev->blkdev->bd_inode->i_mapping; + int index = to >> PAGE_SHIFT; // page index + int offset = to & ~PAGE_MASK; // page offset + int cpylen; + + while (len) { + if ((offset+len) > PAGE_SIZE) + cpylen = PAGE_SIZE - offset; // multiple pages + else + cpylen = len; // this page + len = len - cpylen; + + page = page_read(mapping, index); + if (IS_ERR(page)) + return PTR_ERR(page); + + if (memcmp(page_address(page)+offset, buf, cpylen)) { + lock_page(page); + memcpy(page_address(page) + offset, buf, cpylen); + set_page_dirty(page); + unlock_page(page); + balance_dirty_pages_ratelimited(mapping); + } + page_cache_release(page); + + if (retlen) + *retlen += cpylen; + + buf += cpylen; + offset = 0; + index++; + } + return 0; +} + + +static int block2mtd_write(struct mtd_info *mtd, loff_t to, size_t len, + size_t *retlen, const u_char *buf) +{ + struct block2mtd_dev *dev = mtd->priv; + int err; + + mutex_lock(&dev->write_mutex); + err = _block2mtd_write(dev, buf, to, len, retlen); + mutex_unlock(&dev->write_mutex); + if (err > 0) + err = 0; + return err; +} + + +/* sync the device - wait until the write queue is empty */ +static void block2mtd_sync(struct mtd_info *mtd) +{ + struct block2mtd_dev *dev = mtd->priv; + sync_blockdev(dev->blkdev); + return; +} + + +static void block2mtd_free_device(struct block2mtd_dev *dev) +{ + if (!dev) + return; + + kfree(dev->mtd.name); + + if (dev->blkdev) { + invalidate_mapping_pages(dev->blkdev->bd_inode->i_mapping, + 0, -1); + blkdev_put(dev->blkdev, FMODE_READ|FMODE_WRITE|FMODE_EXCL); + } + + kfree(dev); +} + + +static struct block2mtd_dev *add_device(char *devname, int erase_size, + int timeout) +{ +#ifndef MODULE + int i; +#endif + const fmode_t mode = FMODE_READ | FMODE_WRITE | FMODE_EXCL; + struct block_device *bdev = ERR_PTR(-ENODEV); + struct block2mtd_dev *dev; + char *name; + + if (!devname) + return NULL; + + dev = kzalloc(sizeof(struct block2mtd_dev), GFP_KERNEL); + if (!dev) + return NULL; + + /* Get a handle on the device */ + bdev = blkdev_get_by_path(devname, mode, dev); + +#ifndef MODULE + /* + * We might not have the root device mounted at this point. + * Try to resolve the device name by other means. + */ + for (i = 0; IS_ERR(bdev) && i <= timeout; i++) { + dev_t devt; + + if (i) + /* + * Calling wait_for_device_probe in the first loop + * was not enough, sleep for a bit in subsequent + * go-arounds. + */ + msleep(1000); + wait_for_device_probe(); + + devt = name_to_dev_t(devname); + if (!devt) + continue; + bdev = blkdev_get_by_dev(devt, mode, dev); + } +#endif + + if (IS_ERR(bdev)) { + pr_err("error: cannot open device %s\n", devname); + goto err_free_block2mtd; + } + dev->blkdev = bdev; + + if (MAJOR(bdev->bd_dev) == MTD_BLOCK_MAJOR) { + pr_err("attempting to use an MTD device as a block device\n"); + goto err_free_block2mtd; + } + + if ((long)dev->blkdev->bd_inode->i_size % erase_size) { + pr_err("erasesize must be a divisor of device size\n"); + goto err_free_block2mtd; + } + + mutex_init(&dev->write_mutex); + + /* Setup the MTD structure */ + /* make the name contain the block device in */ + name = kasprintf(GFP_KERNEL, "block2mtd: %s", devname); + if (!name) + goto err_destroy_mutex; + + dev->mtd.name = name; + + dev->mtd.size = dev->blkdev->bd_inode->i_size & PAGE_MASK; + dev->mtd.erasesize = erase_size; + dev->mtd.writesize = 1; + dev->mtd.writebufsize = PAGE_SIZE; + dev->mtd.type = MTD_RAM; + dev->mtd.flags = MTD_CAP_RAM; + dev->mtd._erase = block2mtd_erase; + dev->mtd._write = block2mtd_write; + dev->mtd._sync = block2mtd_sync; + dev->mtd._read = block2mtd_read; + dev->mtd.priv = dev; + dev->mtd.owner = THIS_MODULE; + + if (mtd_device_register(&dev->mtd, NULL, 0)) { + /* Device didn't get added, so free the entry */ + goto err_destroy_mutex; + } + + list_add(&dev->list, &blkmtd_device_list); + pr_info("mtd%d: [%s] erase_size = %dKiB [%d]\n", + dev->mtd.index, + dev->mtd.name + strlen("block2mtd: "), + dev->mtd.erasesize >> 10, dev->mtd.erasesize); + return dev; + +err_destroy_mutex: + mutex_destroy(&dev->write_mutex); +err_free_block2mtd: + block2mtd_free_device(dev); + return NULL; +} + + +/* This function works similar to reguler strtoul. In addition, it + * allows some suffixes for a more human-readable number format: + * ki, Ki, kiB, KiB - multiply result with 1024 + * Mi, MiB - multiply result with 1024^2 + * Gi, GiB - multiply result with 1024^3 + */ +static int ustrtoul(const char *cp, char **endp, unsigned int base) +{ + unsigned long result = simple_strtoul(cp, endp, base); + switch (**endp) { + case 'G' : + result *= 1024; + case 'M': + result *= 1024; + case 'K': + case 'k': + result *= 1024; + /* By dwmw2 editorial decree, "ki", "Mi" or "Gi" are to be used. */ + if ((*endp)[1] == 'i') { + if ((*endp)[2] == 'B') + (*endp) += 3; + else + (*endp) += 2; + } + } + return result; +} + + +static int parse_num(size_t *num, const char *token) +{ + char *endp; + size_t n; + + n = (size_t) ustrtoul(token, &endp, 0); + if (*endp) + return -EINVAL; + + *num = n; + return 0; +} + + +static inline void kill_final_newline(char *str) +{ + char *newline = strrchr(str, '\n'); + if (newline && !newline[1]) + *newline = 0; +} + + +#ifndef MODULE +static int block2mtd_init_called = 0; +/* 80 for device, 12 for erase size */ +static char block2mtd_paramline[80 + 12]; +#endif + +static int block2mtd_setup2(const char *val) +{ + /* 80 for device, 12 for erase size, 80 for name, 8 for timeout */ + char buf[80 + 12 + 80 + 8]; + char *str = buf; + char *token[2]; + char *name; + size_t erase_size = PAGE_SIZE; + unsigned long timeout = MTD_DEFAULT_TIMEOUT; + int i, ret; + + if (strnlen(val, sizeof(buf)) >= sizeof(buf)) { + pr_err("parameter too long\n"); + return 0; + } + + strcpy(str, val); + kill_final_newline(str); + + for (i = 0; i < 2; i++) + token[i] = strsep(&str, ","); + + if (str) { + pr_err("too many arguments\n"); + return 0; + } + + if (!token[0]) { + pr_err("no argument\n"); + return 0; + } + + name = token[0]; + if (strlen(name) + 1 > 80) { + pr_err("device name too long\n"); + return 0; + } + + if (token[1]) { + ret = parse_num(&erase_size, token[1]); + if (ret) { + pr_err("illegal erase size\n"); + return 0; + } + } + + add_device(name, erase_size, timeout); + + return 0; +} + + +static int block2mtd_setup(const char *val, struct kernel_param *kp) +{ +#ifdef MODULE + return block2mtd_setup2(val); +#else + /* If more parameters are later passed in via + /sys/module/block2mtd/parameters/block2mtd + and block2mtd_init() has already been called, + we can parse the argument now. */ + + if (block2mtd_init_called) + return block2mtd_setup2(val); + + /* During early boot stage, we only save the parameters + here. We must parse them later: if the param passed + from kernel boot command line, block2mtd_setup() is + called so early that it is not possible to resolve + the device (even kmalloc() fails). Deter that work to + block2mtd_setup2(). */ + + strlcpy(block2mtd_paramline, val, sizeof(block2mtd_paramline)); + + return 0; +#endif +} + + +module_param_call(block2mtd, block2mtd_setup, NULL, NULL, 0200); +MODULE_PARM_DESC(block2mtd, "Device to use. \"block2mtd=<dev>[,<erasesize>]\""); + +static int __init block2mtd_init(void) +{ + int ret = 0; + +#ifndef MODULE + if (strlen(block2mtd_paramline)) + ret = block2mtd_setup2(block2mtd_paramline); + block2mtd_init_called = 1; +#endif + + return ret; +} + + +static void block2mtd_exit(void) +{ + struct list_head *pos, *next; + + /* Remove the MTD devices */ + list_for_each_safe(pos, next, &blkmtd_device_list) { + struct block2mtd_dev *dev = list_entry(pos, typeof(*dev), list); + block2mtd_sync(&dev->mtd); + mtd_device_unregister(&dev->mtd); + mutex_destroy(&dev->write_mutex); + pr_info("mtd%d: [%s] removed\n", + dev->mtd.index, + dev->mtd.name + strlen("block2mtd: ")); + list_del(&dev->list); + block2mtd_free_device(dev); + } +} + +late_initcall(block2mtd_init); +module_exit(block2mtd_exit); + +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("Joern Engel <joern@lazybastard.org>"); +MODULE_DESCRIPTION("Emulate an MTD using a block device"); |