diff options
Diffstat (limited to 'drivers/mtd/devices/block2mtd.c')
| -rw-r--r-- | drivers/mtd/devices/block2mtd.c | 464 |
1 files changed, 464 insertions, 0 deletions
diff --git a/drivers/mtd/devices/block2mtd.c b/drivers/mtd/devices/block2mtd.c new file mode 100644 index 00000000..7d7000d2 --- /dev/null +++ b/drivers/mtd/devices/block2mtd.c @@ -0,0 +1,464 @@ +/* + * 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 + */ +#include <linux/module.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> + +#define ERROR(fmt, args...) printk(KERN_ERR "block2mtd: " fmt "\n" , ## args) +#define INFO(fmt, args...) printk(KERN_INFO "block2mtd: " fmt "\n" , ## args) + + +/* 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 (!page) + return -ENOMEM; + 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); + 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) { + ERROR("erase failed err = %d", 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 (!page) + return -ENOMEM; + 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 (!page) + return -ENOMEM; + 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); + } + 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); +} + + +/* FIXME: ensure that mtd->size % erase_size == 0 */ +static struct block2mtd_dev *add_device(char *devname, int erase_size) +{ + const fmode_t mode = FMODE_READ | FMODE_WRITE | FMODE_EXCL; + struct block_device *bdev; + 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 + if (IS_ERR(bdev)) { + + /* We might not have rootfs mounted at this point. Try + to resolve the device name by other means. */ + + dev_t devt = name_to_dev_t(devname); + if (devt) + bdev = blkdev_get_by_dev(devt, mode, dev); + } +#endif + + if (IS_ERR(bdev)) { + ERROR("error: cannot open device %s", devname); + goto devinit_err; + } + dev->blkdev = bdev; + + if (MAJOR(bdev->bd_dev) == MTD_BLOCK_MAJOR) { + ERROR("attempting to use an MTD device as a block device"); + goto devinit_err; + } + + 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 devinit_err; + + 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 devinit_err; + } + list_add(&dev->list, &blkmtd_device_list); + INFO("mtd%d: [%s] erase_size = %dKiB [%d]", dev->mtd.index, + dev->mtd.name + strlen("block2mtd: "), + dev->mtd.erasesize >> 10, dev->mtd.erasesize); + return dev; + +devinit_err: + 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; +} + + +#define parse_err(fmt, args...) do { \ + ERROR(fmt, ## args); \ + return 0; \ +} while (0) + +#ifndef MODULE +static int block2mtd_init_called = 0; +static char block2mtd_paramline[80 + 12]; /* 80 for device, 12 for erase size */ +#endif + + +static int block2mtd_setup2(const char *val) +{ + char buf[80 + 12]; /* 80 for device, 12 for erase size */ + char *str = buf; + char *token[2]; + char *name; + size_t erase_size = PAGE_SIZE; + int i, ret; + + if (strnlen(val, sizeof(buf)) >= sizeof(buf)) + parse_err("parameter too long"); + + strcpy(str, val); + kill_final_newline(str); + + for (i = 0; i < 2; i++) + token[i] = strsep(&str, ","); + + if (str) + parse_err("too many arguments"); + + if (!token[0]) + parse_err("no argument"); + + name = token[0]; + if (strlen(name) + 1 > 80) + parse_err("device name too long"); + + if (token[1]) { + ret = parse_num(&erase_size, token[1]); + if (ret) { + parse_err("illegal erase size"); + } + } + + add_device(name, erase_size); + + 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 __devexit 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); + INFO("mtd%d: [%s] removed", dev->mtd.index, + dev->mtd.name + strlen("block2mtd: ")); + list_del(&dev->list); + block2mtd_free_device(dev); + } +} + + +module_init(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"); |