text: /*
   * 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/buffer_head.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;
  
  	if (from > mtd->size)
  		return -EINVAL;
  	if (from + len > mtd->size)
  		len = mtd->size - from;
  
  	if (retlen)
  		*retlen = 0;
  
  	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;
  
  	if (retlen)
  		*retlen = 0;
  	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;
  
  	if (!len)
  		return 0;
  	if (to >= mtd->size)
  		return -ENOSPC;
  	if (to + len > mtd->size)
  		len = mtd->size - to;
  
  	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.type = MTD_RAM;
  	dev->mtd.flags = MTD_CAP_RAM;
  	dev->mtd.erase = block2mtd_erase;
  	dev->mtd.write = block2mtd_write;
  	dev->mtd.writev = default_mtd_writev;
  	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");
  