349 lines
9.4 KiB
C
349 lines
9.4 KiB
C
/*
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* Copyright (c) International Business Machines Corp., 2006
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See
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* the GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*
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* Author: Artem Bityutskiy (Битюцкий Артём), Joern Engel
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*/
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/*
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* This file includes implementation of fake MTD devices for each UBI volume.
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* This sounds strange, but it is in fact quite useful to make MTD-oriented
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* software (including all the legacy software) to work on top of UBI.
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*
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* Gluebi emulates MTD devices of "MTD_UBIVOLUME" type. Their minimal I/O unit
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* size (mtd->writesize) is equivalent to the UBI minimal I/O unit. The
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* eraseblock size is equivalent to the logical eraseblock size of the volume.
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*/
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#include <asm/div64.h>
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#include "ubi.h"
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/**
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* gluebi_get_device - get MTD device reference.
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* @mtd: the MTD device description object
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*
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* This function is called every time the MTD device is being opened and
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* implements the MTD get_device() operation. Returns zero in case of success
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* and a negative error code in case of failure.
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*/
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static int gluebi_get_device(struct mtd_info *mtd)
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{
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struct ubi_volume *vol;
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vol = container_of(mtd, struct ubi_volume, gluebi_mtd);
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/*
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* We do not introduce locks for gluebi reference count because the
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* get_device()/put_device() calls are already serialized at MTD.
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*/
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if (vol->gluebi_refcount > 0) {
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/*
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* The MTD device is already referenced and this is just one
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* more reference. MTD allows many users to open the same
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* volume simultaneously and do not distinguish between
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* readers/writers/exclusive openers as UBI does. So we do not
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* open the UBI volume again - just increase the reference
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* counter and return.
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*/
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vol->gluebi_refcount += 1;
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return 0;
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}
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/*
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* This is the first reference to this UBI volume via the MTD device
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* interface. Open the corresponding volume in read-write mode.
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*/
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vol->gluebi_desc = ubi_open_volume(vol->ubi->ubi_num, vol->vol_id,
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UBI_READWRITE);
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if (IS_ERR(vol->gluebi_desc))
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return PTR_ERR(vol->gluebi_desc);
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vol->gluebi_refcount += 1;
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return 0;
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}
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/**
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* gluebi_put_device - put MTD device reference.
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* @mtd: the MTD device description object
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*
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* This function is called every time the MTD device is being put. Returns
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* zero in case of success and a negative error code in case of failure.
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*/
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static void gluebi_put_device(struct mtd_info *mtd)
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{
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struct ubi_volume *vol;
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vol = container_of(mtd, struct ubi_volume, gluebi_mtd);
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vol->gluebi_refcount -= 1;
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ubi_assert(vol->gluebi_refcount >= 0);
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if (vol->gluebi_refcount == 0)
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ubi_close_volume(vol->gluebi_desc);
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}
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/**
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* gluebi_read - read operation of emulated MTD devices.
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* @mtd: MTD device description object
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* @from: absolute offset from where to read
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* @len: how many bytes to read
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* @retlen: count of read bytes is returned here
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* @buf: buffer to store the read data
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*
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* This function returns zero in case of success and a negative error code in
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* case of failure.
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*/
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static int gluebi_read(struct mtd_info *mtd, loff_t from, size_t len,
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size_t *retlen, unsigned char *buf)
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{
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int err = 0, lnum, offs, total_read;
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struct ubi_volume *vol;
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struct ubi_device *ubi;
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uint64_t tmp = from;
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dbg_gen("read %zd bytes from offset %lld", len, from);
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if (len < 0 || from < 0 || from + len > mtd->size)
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return -EINVAL;
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vol = container_of(mtd, struct ubi_volume, gluebi_mtd);
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ubi = vol->ubi;
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offs = do_div(tmp, mtd->erasesize);
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lnum = tmp;
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total_read = len;
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while (total_read) {
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size_t to_read = mtd->erasesize - offs;
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if (to_read > total_read)
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to_read = total_read;
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err = ubi_eba_read_leb(ubi, vol, lnum, buf, offs, to_read, 0);
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if (err)
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break;
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lnum += 1;
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offs = 0;
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total_read -= to_read;
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buf += to_read;
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}
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*retlen = len - total_read;
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return err;
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}
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/**
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* gluebi_write - write operation of emulated MTD devices.
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* @mtd: MTD device description object
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* @to: absolute offset where to write
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* @len: how many bytes to write
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* @retlen: count of written bytes is returned here
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* @buf: buffer with data to write
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*
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* This function returns zero in case of success and a negative error code in
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* case of failure.
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*/
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static int gluebi_write(struct mtd_info *mtd, loff_t to, size_t len,
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size_t *retlen, const u_char *buf)
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{
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int err = 0, lnum, offs, total_written;
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struct ubi_volume *vol;
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struct ubi_device *ubi;
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uint64_t tmp = to;
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dbg_gen("write %zd bytes to offset %lld", len, to);
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if (len < 0 || to < 0 || len + to > mtd->size)
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return -EINVAL;
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vol = container_of(mtd, struct ubi_volume, gluebi_mtd);
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ubi = vol->ubi;
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if (ubi->ro_mode)
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return -EROFS;
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offs = do_div(tmp, mtd->erasesize);
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lnum = tmp;
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if (len % mtd->writesize || offs % mtd->writesize)
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return -EINVAL;
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total_written = len;
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while (total_written) {
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size_t to_write = mtd->erasesize - offs;
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if (to_write > total_written)
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to_write = total_written;
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err = ubi_eba_write_leb(ubi, vol, lnum, buf, offs, to_write,
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UBI_UNKNOWN);
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if (err)
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break;
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lnum += 1;
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offs = 0;
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total_written -= to_write;
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buf += to_write;
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}
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*retlen = len - total_written;
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return err;
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}
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/**
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* gluebi_erase - erase operation of emulated MTD devices.
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* @mtd: the MTD device description object
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* @instr: the erase operation description
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*
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* This function calls the erase callback when finishes. Returns zero in case
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* of success and a negative error code in case of failure.
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*/
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static int gluebi_erase(struct mtd_info *mtd, struct erase_info *instr)
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{
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int err, i, lnum, count;
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struct ubi_volume *vol;
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struct ubi_device *ubi;
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dbg_gen("erase %u bytes at offset %u", instr->len, instr->addr);
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if (instr->addr < 0 || instr->addr > mtd->size - mtd->erasesize)
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return -EINVAL;
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if (instr->len < 0 || instr->addr + instr->len > mtd->size)
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return -EINVAL;
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if (instr->addr % mtd->writesize || instr->len % mtd->writesize)
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return -EINVAL;
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lnum = instr->addr / mtd->erasesize;
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count = instr->len / mtd->erasesize;
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vol = container_of(mtd, struct ubi_volume, gluebi_mtd);
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ubi = vol->ubi;
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if (ubi->ro_mode)
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return -EROFS;
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for (i = 0; i < count; i++) {
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err = ubi_eba_unmap_leb(ubi, vol, lnum + i);
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if (err)
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goto out_err;
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}
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/*
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* MTD erase operations are synchronous, so we have to make sure the
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* physical eraseblock is wiped out.
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*/
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err = ubi_wl_flush(ubi);
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if (err)
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goto out_err;
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instr->state = MTD_ERASE_DONE;
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mtd_erase_callback(instr);
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return 0;
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out_err:
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instr->state = MTD_ERASE_FAILED;
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instr->fail_addr = lnum * mtd->erasesize;
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return err;
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}
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/**
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* ubi_create_gluebi - initialize gluebi for an UBI volume.
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* @ubi: UBI device description object
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* @vol: volume description object
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*
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* This function is called when an UBI volume is created in order to create
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* corresponding fake MTD device. Returns zero in case of success and a
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* negative error code in case of failure.
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*/
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int ubi_create_gluebi(struct ubi_device *ubi, struct ubi_volume *vol)
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{
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struct mtd_info *mtd = &vol->gluebi_mtd;
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mtd->name = kmemdup(vol->name, vol->name_len + 1, GFP_KERNEL);
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if (!mtd->name)
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return -ENOMEM;
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mtd->type = MTD_UBIVOLUME;
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if (!ubi->ro_mode)
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mtd->flags = MTD_WRITEABLE;
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mtd->writesize = ubi->min_io_size;
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mtd->owner = THIS_MODULE;
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mtd->erasesize = vol->usable_leb_size;
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mtd->read = gluebi_read;
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mtd->write = gluebi_write;
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mtd->erase = gluebi_erase;
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mtd->get_device = gluebi_get_device;
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mtd->put_device = gluebi_put_device;
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/*
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* In case of dynamic volume, MTD device size is just volume size. In
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* case of a static volume the size is equivalent to the amount of data
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* bytes.
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*/
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if (vol->vol_type == UBI_DYNAMIC_VOLUME)
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mtd->size = vol->usable_leb_size * vol->reserved_pebs;
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else
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mtd->size = vol->used_bytes;
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if (add_mtd_device(mtd)) {
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ubi_err("cannot not add MTD device");
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kfree(mtd->name);
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return -ENFILE;
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}
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dbg_gen("added mtd%d (\"%s\"), size %u, EB size %u",
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mtd->index, mtd->name, mtd->size, mtd->erasesize);
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return 0;
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}
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/**
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* ubi_destroy_gluebi - close gluebi for an UBI volume.
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* @vol: volume description object
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*
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* This function is called when an UBI volume is removed in order to remove
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* corresponding fake MTD device. Returns zero in case of success and a
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* negative error code in case of failure.
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*/
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int ubi_destroy_gluebi(struct ubi_volume *vol)
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{
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int err;
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struct mtd_info *mtd = &vol->gluebi_mtd;
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dbg_gen("remove mtd%d", mtd->index);
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err = del_mtd_device(mtd);
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if (err)
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return err;
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kfree(mtd->name);
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return 0;
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}
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/**
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* ubi_gluebi_updated - UBI volume was updated notifier.
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* @vol: volume description object
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*
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* This function is called every time an UBI volume is updated. This function
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* does nothing if volume @vol is dynamic, and changes MTD device size if the
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* volume is static. This is needed because static volumes cannot be read past
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* data they contain.
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*/
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void ubi_gluebi_updated(struct ubi_volume *vol)
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{
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struct mtd_info *mtd = &vol->gluebi_mtd;
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if (vol->vol_type == UBI_STATIC_VOLUME)
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mtd->size = vol->used_bytes;
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}
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