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27b08bf3c3
Removing some boilerplate by using module_mtd_blktrans instead of calling register and unregister in the otherwise empty init/exit functions. Signed-off-by: Dejin Zheng <zhengdejin5@gmail.com> Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com> Link: https://lore.kernel.org/linux-mtd/20210213164600.409061-5-zhengdejin5@gmail.com
354 lines
8.5 KiB
C
354 lines
8.5 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* Direct MTD block device access
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*
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* Copyright © 1999-2010 David Woodhouse <dwmw2@infradead.org>
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* Copyright © 2000-2003 Nicolas Pitre <nico@fluxnic.net>
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*/
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#include <linux/fs.h>
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#include <linux/init.h>
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/sched.h>
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#include <linux/slab.h>
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#include <linux/types.h>
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#include <linux/vmalloc.h>
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#include <linux/mtd/mtd.h>
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#include <linux/mtd/blktrans.h>
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#include <linux/mutex.h>
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#include <linux/major.h>
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struct mtdblk_dev {
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struct mtd_blktrans_dev mbd;
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int count;
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struct mutex cache_mutex;
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unsigned char *cache_data;
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unsigned long cache_offset;
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unsigned int cache_size;
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enum { STATE_EMPTY, STATE_CLEAN, STATE_DIRTY } cache_state;
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};
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/*
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* Cache stuff...
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*
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* Since typical flash erasable sectors are much larger than what Linux's
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* buffer cache can handle, we must implement read-modify-write on flash
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* sectors for each block write requests. To avoid over-erasing flash sectors
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* and to speed things up, we locally cache a whole flash sector while it is
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* being written to until a different sector is required.
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*/
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static int erase_write (struct mtd_info *mtd, unsigned long pos,
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unsigned int len, const char *buf)
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{
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struct erase_info erase;
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size_t retlen;
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int ret;
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/*
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* First, let's erase the flash block.
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*/
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erase.addr = pos;
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erase.len = len;
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ret = mtd_erase(mtd, &erase);
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if (ret) {
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printk (KERN_WARNING "mtdblock: erase of region [0x%lx, 0x%x] "
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"on \"%s\" failed\n",
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pos, len, mtd->name);
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return ret;
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}
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/*
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* Next, write the data to flash.
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*/
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ret = mtd_write(mtd, pos, len, &retlen, buf);
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if (ret)
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return ret;
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if (retlen != len)
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return -EIO;
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return 0;
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}
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static int write_cached_data (struct mtdblk_dev *mtdblk)
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{
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struct mtd_info *mtd = mtdblk->mbd.mtd;
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int ret;
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if (mtdblk->cache_state != STATE_DIRTY)
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return 0;
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pr_debug("mtdblock: writing cached data for \"%s\" "
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"at 0x%lx, size 0x%x\n", mtd->name,
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mtdblk->cache_offset, mtdblk->cache_size);
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ret = erase_write (mtd, mtdblk->cache_offset,
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mtdblk->cache_size, mtdblk->cache_data);
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/*
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* Here we could arguably set the cache state to STATE_CLEAN.
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* However this could lead to inconsistency since we will not
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* be notified if this content is altered on the flash by other
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* means. Let's declare it empty and leave buffering tasks to
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* the buffer cache instead.
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*
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* If this cache_offset points to a bad block, data cannot be
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* written to the device. Clear cache_state to avoid writing to
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* bad blocks repeatedly.
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*/
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if (ret == 0 || ret == -EIO)
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mtdblk->cache_state = STATE_EMPTY;
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return ret;
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}
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static int do_cached_write (struct mtdblk_dev *mtdblk, unsigned long pos,
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int len, const char *buf)
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{
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struct mtd_info *mtd = mtdblk->mbd.mtd;
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unsigned int sect_size = mtdblk->cache_size;
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size_t retlen;
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int ret;
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pr_debug("mtdblock: write on \"%s\" at 0x%lx, size 0x%x\n",
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mtd->name, pos, len);
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if (!sect_size)
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return mtd_write(mtd, pos, len, &retlen, buf);
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while (len > 0) {
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unsigned long sect_start = (pos/sect_size)*sect_size;
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unsigned int offset = pos - sect_start;
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unsigned int size = sect_size - offset;
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if( size > len )
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size = len;
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if (size == sect_size) {
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/*
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* We are covering a whole sector. Thus there is no
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* need to bother with the cache while it may still be
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* useful for other partial writes.
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*/
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ret = erase_write (mtd, pos, size, buf);
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if (ret)
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return ret;
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} else {
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/* Partial sector: need to use the cache */
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if (mtdblk->cache_state == STATE_DIRTY &&
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mtdblk->cache_offset != sect_start) {
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ret = write_cached_data(mtdblk);
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if (ret)
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return ret;
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}
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if (mtdblk->cache_state == STATE_EMPTY ||
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mtdblk->cache_offset != sect_start) {
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/* fill the cache with the current sector */
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mtdblk->cache_state = STATE_EMPTY;
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ret = mtd_read(mtd, sect_start, sect_size,
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&retlen, mtdblk->cache_data);
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if (ret)
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return ret;
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if (retlen != sect_size)
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return -EIO;
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mtdblk->cache_offset = sect_start;
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mtdblk->cache_size = sect_size;
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mtdblk->cache_state = STATE_CLEAN;
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}
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/* write data to our local cache */
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memcpy (mtdblk->cache_data + offset, buf, size);
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mtdblk->cache_state = STATE_DIRTY;
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}
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buf += size;
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pos += size;
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len -= size;
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}
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return 0;
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}
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static int do_cached_read (struct mtdblk_dev *mtdblk, unsigned long pos,
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int len, char *buf)
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{
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struct mtd_info *mtd = mtdblk->mbd.mtd;
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unsigned int sect_size = mtdblk->cache_size;
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size_t retlen;
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int ret;
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pr_debug("mtdblock: read on \"%s\" at 0x%lx, size 0x%x\n",
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mtd->name, pos, len);
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if (!sect_size)
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return mtd_read(mtd, pos, len, &retlen, buf);
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while (len > 0) {
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unsigned long sect_start = (pos/sect_size)*sect_size;
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unsigned int offset = pos - sect_start;
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unsigned int size = sect_size - offset;
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if (size > len)
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size = len;
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/*
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* Check if the requested data is already cached
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* Read the requested amount of data from our internal cache if it
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* contains what we want, otherwise we read the data directly
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* from flash.
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*/
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if (mtdblk->cache_state != STATE_EMPTY &&
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mtdblk->cache_offset == sect_start) {
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memcpy (buf, mtdblk->cache_data + offset, size);
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} else {
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ret = mtd_read(mtd, pos, size, &retlen, buf);
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if (ret)
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return ret;
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if (retlen != size)
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return -EIO;
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}
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buf += size;
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pos += size;
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len -= size;
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}
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return 0;
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}
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static int mtdblock_readsect(struct mtd_blktrans_dev *dev,
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unsigned long block, char *buf)
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{
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struct mtdblk_dev *mtdblk = container_of(dev, struct mtdblk_dev, mbd);
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return do_cached_read(mtdblk, block<<9, 512, buf);
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}
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static int mtdblock_writesect(struct mtd_blktrans_dev *dev,
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unsigned long block, char *buf)
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{
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struct mtdblk_dev *mtdblk = container_of(dev, struct mtdblk_dev, mbd);
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if (unlikely(!mtdblk->cache_data && mtdblk->cache_size)) {
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mtdblk->cache_data = vmalloc(mtdblk->mbd.mtd->erasesize);
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if (!mtdblk->cache_data)
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return -EINTR;
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/* -EINTR is not really correct, but it is the best match
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* documented in man 2 write for all cases. We could also
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* return -EAGAIN sometimes, but why bother?
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*/
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}
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return do_cached_write(mtdblk, block<<9, 512, buf);
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}
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static int mtdblock_open(struct mtd_blktrans_dev *mbd)
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{
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struct mtdblk_dev *mtdblk = container_of(mbd, struct mtdblk_dev, mbd);
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pr_debug("mtdblock_open\n");
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if (mtdblk->count) {
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mtdblk->count++;
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return 0;
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}
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/* OK, it's not open. Create cache info for it */
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mtdblk->count = 1;
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mutex_init(&mtdblk->cache_mutex);
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mtdblk->cache_state = STATE_EMPTY;
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if (!(mbd->mtd->flags & MTD_NO_ERASE) && mbd->mtd->erasesize) {
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mtdblk->cache_size = mbd->mtd->erasesize;
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mtdblk->cache_data = NULL;
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}
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pr_debug("ok\n");
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return 0;
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}
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static void mtdblock_release(struct mtd_blktrans_dev *mbd)
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{
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struct mtdblk_dev *mtdblk = container_of(mbd, struct mtdblk_dev, mbd);
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pr_debug("mtdblock_release\n");
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mutex_lock(&mtdblk->cache_mutex);
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write_cached_data(mtdblk);
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mutex_unlock(&mtdblk->cache_mutex);
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if (!--mtdblk->count) {
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/*
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* It was the last usage. Free the cache, but only sync if
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* opened for writing.
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*/
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if (mbd->file_mode & FMODE_WRITE)
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mtd_sync(mbd->mtd);
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vfree(mtdblk->cache_data);
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}
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pr_debug("ok\n");
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}
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static int mtdblock_flush(struct mtd_blktrans_dev *dev)
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{
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struct mtdblk_dev *mtdblk = container_of(dev, struct mtdblk_dev, mbd);
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int ret;
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mutex_lock(&mtdblk->cache_mutex);
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ret = write_cached_data(mtdblk);
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mutex_unlock(&mtdblk->cache_mutex);
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mtd_sync(dev->mtd);
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return ret;
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}
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static void mtdblock_add_mtd(struct mtd_blktrans_ops *tr, struct mtd_info *mtd)
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{
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struct mtdblk_dev *dev = kzalloc(sizeof(*dev), GFP_KERNEL);
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if (!dev)
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return;
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dev->mbd.mtd = mtd;
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dev->mbd.devnum = mtd->index;
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dev->mbd.size = mtd->size >> 9;
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dev->mbd.tr = tr;
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if (!(mtd->flags & MTD_WRITEABLE))
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dev->mbd.readonly = 1;
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if (add_mtd_blktrans_dev(&dev->mbd))
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kfree(dev);
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}
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static void mtdblock_remove_dev(struct mtd_blktrans_dev *dev)
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{
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del_mtd_blktrans_dev(dev);
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}
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static struct mtd_blktrans_ops mtdblock_tr = {
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.name = "mtdblock",
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.major = MTD_BLOCK_MAJOR,
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.part_bits = 0,
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.blksize = 512,
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.open = mtdblock_open,
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.flush = mtdblock_flush,
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.release = mtdblock_release,
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.readsect = mtdblock_readsect,
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.writesect = mtdblock_writesect,
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.add_mtd = mtdblock_add_mtd,
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.remove_dev = mtdblock_remove_dev,
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.owner = THIS_MODULE,
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};
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module_mtd_blktrans(mtdblock_tr);
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MODULE_LICENSE("GPL");
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MODULE_AUTHOR("Nicolas Pitre <nico@fluxnic.net> et al.");
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MODULE_DESCRIPTION("Caching read/erase/writeback block device emulation access to MTD devices");
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