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/*

 * $Id: block2mtd.c,v 1.30 2005/11/29 14:48:32 gleixner Exp $

 *

 * block2mtd.c - create an mtd from a block device

 *

 * Copyright (C) 2001,2002      Simon Evans <spse@secret.org.uk>

 * Copyright (C) 2004-2006      Jörn 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>

#define VERSION "$Revision: 1.30 $"

#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;

        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);

                close_bdev_excl(dev->blkdev);

        }

        kfree(dev);

}

/* FIXME: ensure that mtd->size % erase_size == 0 */

static struct block2mtd_dev *add_device(char *devname, int erase_size)

{

        struct block_device *bdev;

        struct block2mtd_dev *dev;

        if (!devname)

                return NULL;

        dev = kzalloc(sizeof(struct block2mtd_dev), GFP_KERNEL);

        if (!dev)

                return NULL;

        /* Get a handle on the device */

        bdev = open_bdev_excl(devname, O_RDWR, NULL);

#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 = open_by_devnum(devt, FMODE_WRITE | FMODE_READ);

                }

        }

#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 */

        dev->mtd.name = kmalloc(sizeof("block2mtd: ") + strlen(devname),

                        GFP_KERNEL);

        if (!dev->mtd.name)

                goto devinit_err;

        sprintf(dev->mtd.name, "block2mtd: %s", devname);

        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 (add_mtd_device(&dev->mtd)) {

                /* Device didnt 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("blkmtd: "),

                        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("block2mtd: " fmt "\n", ## 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) {

                        kfree(name);

                        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;

        INFO("version " VERSION);

#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);

                del_mtd_device(&dev->mtd);

                INFO("mtd%d: [%s] removed", dev->mtd.index,

                                dev->mtd.name + strlen("blkmtd: "));

                list_del(&dev->list);

                block2mtd_free_device(dev);

        }

}

module_init(block2mtd_init);

module_exit(block2mtd_exit);

MODULE_LICENSE("GPL");

MODULE_AUTHOR("Simon Evans <spse@secret.org.uk> and others");

MODULE_DESCRIPTION("Emulate an MTD using a block device");