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