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Diffstat (limited to '')
| -rw-r--r-- | drivers/mtd/ubi/gluebi.c | 500 |
1 files changed, 500 insertions, 0 deletions
diff --git a/drivers/mtd/ubi/gluebi.c b/drivers/mtd/ubi/gluebi.c new file mode 100644 index 000000000..cc547b37c --- /dev/null +++ b/drivers/mtd/ubi/gluebi.c @@ -0,0 +1,500 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Copyright (c) International Business Machines Corp., 2006 + * + * 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, ...) \ + pr_err("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 (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/meta 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); + 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); + 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, bytes_left; + struct gluebi_device *gluebi; + + gluebi = container_of(mtd, struct gluebi_device, mtd); + lnum = div_u64_rem(from, mtd->erasesize, &offs); + bytes_left = len; + while (bytes_left) { + size_t to_read = mtd->erasesize - offs; + + if (to_read > bytes_left) + to_read = bytes_left; + + err = ubi_read(gluebi->desc, lnum, buf, offs, to_read); + if (err) + break; + + lnum += 1; + offs = 0; + bytes_left -= to_read; + buf += to_read; + } + + *retlen = len - bytes_left; + 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, bytes_left; + struct gluebi_device *gluebi; + + gluebi = container_of(mtd, struct gluebi_device, mtd); + lnum = div_u64_rem(to, mtd->erasesize, &offs); + + if (len % mtd->writesize || offs % mtd->writesize) + return -EINVAL; + + bytes_left = len; + while (bytes_left) { + size_t to_write = mtd->erasesize - offs; + + if (to_write > bytes_left) + to_write = bytes_left; + + err = ubi_leb_write(gluebi->desc, lnum, buf, offs, to_write); + if (err) + break; + + lnum += 1; + offs = 0; + bytes_left -= to_write; + buf += to_write; + } + + *retlen = len - bytes_left; + 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 (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); + + 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; + + return 0; + +out_err: + 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 (mtd_device_register(mtd, NULL, 0)) { + 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 = mtd_device_unregister(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 = mtd_device_unregister(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"); |