drivers/mtd/devices/block2mtd.c - kernel/mindspeed - Git at Google

 /*
  * 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");
	/*
	* 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");