/*
* Copyright (c) International Business Machines Corp., 2006
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See
* the GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
* Author: Artem Bityutskiy (Битюцкий Артём), Joern Engel
*/
/*
* This is a small driver which implements fake MTD devices on top of UBI
* volumes. This sounds strange, but it is in fact quite useful to make
* MTD-oriented software (including all the legacy software) work on top of
* UBI.
*
* Gluebi emulates MTD devices of "MTD_UBIVOLUME" type. Their minimal I/O unit
* size (@mtd->writesize) is equivalent to the UBI minimal I/O unit. The
* eraseblock size is equivalent to the logical eraseblock size of the volume.
*/
#include <linux/err.h>
#include <linux/list.h>
#include <linux/slab.h>
#include <linux/sched.h>
#include <linux/math64.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/mtd/ubi.h>
#include <linux/mtd/mtd.h>
#include "ubi-media.h"
#define err_msg(fmt, ...) \
printk(KERN_DEBUG "gluebi (pid %d): %s: " fmt "\n", \
current->pid, __func__, ##__VA_ARGS__)
/**
* struct gluebi_device - a gluebi device description data structure.
* @mtd: emulated MTD device description object
* @refcnt: gluebi device reference count
* @desc: UBI volume descriptor
* @ubi_num: UBI device number this gluebi device works on
* @vol_id: ID of UBI volume this gluebi device works on
* @list: link in a list of gluebi devices
*/
struct gluebi_device {
struct mtd_info mtd;
int refcnt;
struct ubi_volume_desc *desc;
int ubi_num;
int vol_id;
struct list_head list;
};
/* List of all gluebi devices */
static LIST_HEAD(gluebi_devices);
static DEFINE_MUTEX(devices_mutex);
/**
* find_gluebi_nolock - find a gluebi device.
* @ubi_num: UBI device number
* @vol_id: volume ID
*
* This function seraches for gluebi device corresponding to UBI device
* @ubi_num and UBI volume @vol_id. Returns the gluebi device description
* object in case of success and %NULL in case of failure. The caller has to
* have the &devices_mutex locked.
*/
static struct gluebi_device *find_gluebi_nolock(int ubi_num, int vol_id)
{
struct gluebi_device *gluebi;
list_for_each_entry(gluebi, &gluebi_devices, list)
if (gluebi->ubi_num == ubi_num && gluebi->vol_id == vol_id)
return gluebi;
return NULL;
}
/**
* gluebi_get_device - get MTD device reference.
* @mtd: the MTD device description object
*
* This function is called every time the MTD device is being opened and
* implements the MTD get_device() operation. Returns zero in case of success
* and a negative error code in case of failure.
*/
static int gluebi_get_device(struct mtd_info *mtd)
{
struct gluebi_device *gluebi;
int ubi_mode = UBI_READONLY;
if (!try_module_get(THIS_MODULE))
return -ENODEV;
if (mtd->flags & MTD_WRITEABLE)
ubi_mode = UBI_READWRITE;
gluebi = container_of(mtd, struct gluebi_device, mtd);
mutex_lock(&devices_mutex);
if (gluebi->refcnt > 0) {
/*
* The MTD device is already referenced and this is just one
* more reference. MTD allows many users to open the same
* volume simultaneously and do not distinguish between
* readers/writers/exclusive openers as UBI does. So we do not
* open the UBI volume again - just increase the reference
* counter and return.
*/
gluebi->refcnt += 1;
mutex_unlock(&devices_mutex);
return 0;
}
/*
* This is the first reference to this UBI volume via the MTD device
* interface. Open the corresponding volume in read-write mode.
*/
gluebi->desc = ubi_open_volume(gluebi->ubi_num, gluebi->vol_id,
ubi_mode);
if (IS_ERR(gluebi->desc)) {
mutex_unlock(&devices_mutex);
module_put(THIS_MODULE);
return PTR_ERR(gluebi->desc);
}
gluebi->refcnt += 1;
mutex_unlock(&devices_mutex);
return 0;
}
/**
* gluebi_put_device - put MTD device reference.
* @mtd: the MTD device description object
*
* This function is called every time the MTD device is being put. Returns
* zero in case of success and a negative error code in case of failure.
*/
static void gluebi_put_device(struct mtd_info *mtd)
{
struct gluebi_device *gluebi;
gluebi = container_of(mtd, struct gluebi_device, mtd);
mutex_lock(&devices_mutex);
gluebi->refcnt -= 1;
if (gluebi->refcnt == 0)
ubi_close_volume(gluebi->desc);
module_put(THIS_MODULE);
mutex_unlock(&devices_mutex);
}
/**
* gluebi_read - read operation of emulated MTD devices.
* @mtd: MTD device description object
* @from: absolute offset from where to read
* @len: how many bytes to read
* @retlen: count of read bytes is returned here
* @buf: buffer to store the read data
*
* This function returns zero in case of success and a negative error code in
* case of failure.
*/
static int gluebi_read(struct mtd_info *mtd, loff_t from, size_t len,
size_t *retlen, unsigned char *buf)
{
int err = 0, lnum, offs, total_read;
struct gluebi_device *gluebi;
if (len < 0 || from < 0 || from + len > mtd->size)
return -EINVAL;
gluebi = container_of(mtd, struct gluebi_device, mtd);
lnum = div_u64_rem(from, mtd->erasesize, &offs);
total_read = len;
while (total_read) {
size_t to_read = mtd->erasesize - offs;
if (to_read > total_read)
to_read = total_read;
err = ubi_read(gluebi->desc, lnum, buf, offs, to_read);
if (err)
break;
lnum += 1;
offs = 0;
total_read -= to_read;
buf += to_read;
}
*retlen = len - total_read;
return err;
}
/**
* gluebi_write - write operation of emulated MTD devices.
* @mtd: MTD device description object
* @to: absolute offset where to write
* @len: how many bytes to write
* @retlen: count of written bytes is returned here
* @buf: buffer with data to write
*
* This function returns zero in case of success and a negative error code in
* case of failure.
*/
static int gluebi_write(struct mtd_info *mtd, loff_t to, size_t len,
size_t *retlen, const u_char *buf)
{
int err = 0, lnum, offs, total_written;
struct gluebi_device *gluebi;
if (len < 0 || to < 0 || len + to > mtd->size)
return -EINVAL;
gluebi = container_of(mtd, struct gluebi_device, mtd);
if (!(mtd->flags & MTD_WRITEABLE))
return -EROFS;
lnum = div_u64_rem(to, mtd->erasesize, &offs);
if (len % mtd->writesize || offs % mtd->writesize)
return -EINVAL;
total_written = len;
while (total_written) {
size_t to_write = mtd->erasesize - offs;
if (to_write > total_written)
to_write = total_written;
err = ubi_write(gluebi->desc, lnum, buf, offs, to_write);
if (err)
break;
lnum += 1;
offs = 0;
total_written -= to_write;
buf += to_write;
}
*retlen = len - total_written;
return err;
}
/**
* gluebi_erase - erase operation of emulated MTD devices.
* @mtd: the MTD device description object
* @instr: the erase operation description
*
* This function calls the erase callback when finishes. Returns zero in case
* of success and a negative error code in case of failure.
*/
static int gluebi_erase(struct mtd_info *mtd, struct erase_info *instr)
{
int err, i, lnum, count;
struct gluebi_device *gluebi;
if (instr->addr < 0 || instr->addr > mtd->size - mtd->erasesize)
return -EINVAL;
if (instr->len < 0 || instr->addr + instr->len > mtd->size)
return -EINVAL;
if (mtd_mod_by_ws(instr->addr, mtd) || mtd_mod_by_ws(instr->len, mtd))
return -EINVAL;
lnum = mtd_div_by_eb(instr->addr, mtd);
count = mtd_div_by_eb(instr->len, mtd);
gluebi = container_of(mtd, struct gluebi_device, mtd);
if (!(mtd->flags & MTD_WRITEABLE))
return -EROFS;
for (i = 0; i < count - 1; i++) {
err = ubi_leb_unmap(gluebi->desc, lnum + i);
if (err)
goto out_err;
}
/*
* MTD erase operations are synchronous, so we have to make sure the
* physical eraseblock is wiped out.
*
* Thus, perform leb_erase instead of leb_unmap operation - leb_erase
* will wait for the end of operations
*/
err = ubi_leb_erase(gluebi->desc, lnum + i);
if (err)
goto out_err;
instr->state = MTD_ERASE_DONE;
mtd_erase_callback(instr);
return 0;
out_err:
instr->state = MTD_ERASE_FAILED;
instr->fail_addr = (long long)lnum * mtd->erasesize;
return err;
}
/**
* gluebi_create - create a gluebi device for an UBI volume.
* @di: UBI device description object
* @vi: UBI volume description object
*
* This function is called when a new UBI volume is created in order to create
* corresponding fake MTD device. Returns zero in case of success and a
* negative error code in case of failure.
*/
static int gluebi_create(struct ubi_device_info *di,
struct ubi_volume_info *vi)
{
struct gluebi_device *gluebi, *g;
struct mtd_info *mtd;
gluebi = kzalloc(sizeof(struct gluebi_device), GFP_KERNEL);
if (!gluebi)
return -ENOMEM;
mtd = &gluebi->mtd;
mtd->name = kmemdup(vi->name, vi->name_len + 1, GFP_KERNEL);
if (!mtd->name) {
kfree(gluebi);
return -ENOMEM;
}
gluebi->vol_id = vi->vol_id;
gluebi->ubi_num = vi->ubi_num;
mtd->type = MTD_UBIVOLUME;
if (!di->ro_mode)
mtd->flags = MTD_WRITEABLE;
mtd->owner = THIS_MODULE;
mtd->writesize = di->min_io_size;
mtd->erasesize = vi->usable_leb_size;
mtd->read = gluebi_read;
mtd->write = gluebi_write;
mtd->erase = gluebi_erase;
mtd->get_device = gluebi_get_device;
mtd->put_device = gluebi_put_device;
/*
* In case of dynamic a volume, MTD device size is just volume size. In
* case of a static volume the size is equivalent to the amount of data
* bytes.
*/
if (vi->vol_type == UBI_DYNAMIC_VOLUME)
mtd->size = (unsigned long long)vi->usable_leb_size * vi->size;
else
mtd->size = vi->used_bytes;
/* Just a sanity check - make sure this gluebi device does not exist */
mutex_lock(&devices_mutex);
g = find_gluebi_nolock(vi->ubi_num, vi->vol_id);
if (g)
err_msg("gluebi MTD device %d form UBI device %d volume %d "
"already exists", g->mtd.index, vi->ubi_num,
vi->vol_id);
mutex_unlock(&devices_mutex);
if (add_mtd_device(mtd)) {
err_msg("cannot add MTD device");
kfree(mtd->name);
kfree(gluebi);
return -ENFILE;
}
mutex_lock(&devices_mutex);
list_add_tail(&gluebi->list, &gluebi_devices);
mutex_unlock(&devices_mutex);
return 0;
}
/**
* gluebi_remove - remove a gluebi device.
* @vi: UBI volume description object
*
* This function is called when an UBI volume is removed and it removes
* corresponding fake MTD device. Returns zero in case of success and a
* negative error code in case of failure.
*/
static int gluebi_remove(struct ubi_volume_info *vi)
{
int err = 0;
struct mtd_info *mtd;
struct gluebi_device *gluebi;
mutex_lock(&devices_mutex);
gluebi = find_gluebi_nolock(vi->ubi_num, vi->vol_id);
if (!gluebi) {
err_msg("got remove notification for unknown UBI device %d "
"volume %d", vi->ubi_num, vi->vol_id);
err = -ENOENT;
} else if (gluebi->refcnt)
err = -EBUSY;
else
list_del(&gluebi->list);
mutex_unlock(&devices_mutex);
if (err)
return err;
mtd = &gluebi->mtd;
err = del_mtd_device(mtd);
if (err) {
err_msg("cannot remove fake MTD device %d, UBI device %d, "
"volume %d, error %d", mtd->index, gluebi->ubi_num,
gluebi->vol_id, err);
mutex_lock(&devices_mutex);
list_add_tail(&gluebi->list, &gluebi_devices);
mutex_unlock(&devices_mutex);
return err;
}
kfree(mtd->name);
kfree(gluebi);
return 0;
}
/**
* gluebi_updated - UBI volume was updated notifier.
* @vi: volume info structure
*
* This function is called every time an UBI volume is updated. It does nothing
* if te volume @vol is dynamic, and changes MTD device size if the
* volume is static. This is needed because static volumes cannot be read past
* data they contain. This function returns zero in case of success and a
* negative error code in case of error.
*/
static int gluebi_updated(struct ubi_volume_info *vi)
{
struct gluebi_device *gluebi;
mutex_lock(&devices_mutex);
gluebi = find_gluebi_nolock(vi->ubi_num, vi->vol_id);
if (!gluebi) {
mutex_unlock(&devices_mutex);
err_msg("got update notification for unknown UBI device %d "
"volume %d", vi->ubi_num, vi->vol_id);
return -ENOENT;
}
if (vi->vol_type == UBI_STATIC_VOLUME)
gluebi->mtd.size = vi->used_bytes;
mutex_unlock(&devices_mutex);
return 0;
}
/**
* gluebi_resized - UBI volume was re-sized notifier.
* @vi: volume info structure
*
* This function is called every time an UBI volume is re-size. It changes the
* corresponding fake MTD device size. This function returns zero in case of
* success and a negative error code in case of error.
*/
static int gluebi_resized(struct ubi_volume_info *vi)
{
struct gluebi_device *gluebi;
mutex_lock(&devices_mutex);
gluebi = find_gluebi_nolock(vi->ubi_num, vi->vol_id);
if (!gluebi) {
mutex_unlock(&devices_mutex);
err_msg("got update notification for unknown UBI device %d "
"volume %d", vi->ubi_num, vi->vol_id);
return -ENOENT;
}
gluebi->mtd.size = vi->used_bytes;
mutex_unlock(&devices_mutex);
return 0;
}
/**
* gluebi_notify - UBI notification handler.
* @nb: registered notifier block
* @l: notification type
* @ptr: pointer to the &struct ubi_notification object
*/
static int gluebi_notify(struct notifier_block *nb, unsigned long l,
void *ns_ptr)
{
struct ubi_notification *nt = ns_ptr;
switch (l) {
case UBI_VOLUME_ADDED:
gluebi_create(&nt->di, &nt->vi);
break;
case UBI_VOLUME_REMOVED:
gluebi_remove(&nt->vi);
break;
case UBI_VOLUME_RESIZED:
gluebi_resized(&nt->vi);
break;
case UBI_VOLUME_UPDATED:
gluebi_updated(&nt->vi);
break;
default:
break;
}
return NOTIFY_OK;
}
static struct notifier_block gluebi_notifier = {
.notifier_call = gluebi_notify,
};
static int __init ubi_gluebi_init(void)
{
return ubi_register_volume_notifier(&gluebi_notifier, 0);
}
static void __exit ubi_gluebi_exit(void)
{
struct gluebi_device *gluebi, *g;
list_for_each_entry_safe(gluebi, g, &gluebi_devices, list) {
int err;
struct mtd_info *mtd = &gluebi->mtd;
err = del_mtd_device(mtd);
if (err)
err_msg("error %d while removing gluebi MTD device %d, "
"UBI device %d, volume %d - ignoring", err,
mtd->index, gluebi->ubi_num, gluebi->vol_id);
kfree(mtd->name);
kfree(gluebi);
}
ubi_unregister_volume_notifier(&gluebi_notifier);
}
module_init(ubi_gluebi_init);
module_exit(ubi_gluebi_exit);
MODULE_DESCRIPTION("MTD emulation layer over UBI volumes");
MODULE_AUTHOR("Artem Bityutskiy, Joern Engel");
MODULE_LICENSE("GPL");
