Linux-2.6.12-rc2
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
This commit is contained in:
Linus Torvalds
394
drivers/mtd/mtdblock.c
Normal file
394
drivers/mtd/mtdblock.c
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@@ -0,0 +1,394 @@
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/*
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* Direct MTD block device access
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*
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* $Id: mtdblock.c,v 1.66 2004/11/25 13:52:52 joern Exp $
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*
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* (C) 2000-2003 Nicolas Pitre <nico@cam.org>
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* (C) 1999-2003 David Woodhouse <dwmw2@infradead.org>
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*/
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#include <linux/config.h>
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#include <linux/types.h>
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#include <linux/module.h>
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#include <linux/kernel.h>
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#include <linux/fs.h>
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#include <linux/init.h>
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#include <linux/slab.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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static struct mtdblk_dev {
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struct mtd_info *mtd;
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int count;
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struct semaphore cache_sem;
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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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} *mtdblks[MAX_MTD_DEVICES];
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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 void erase_callback(struct erase_info *done)
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{
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wait_queue_head_t *wait_q = (wait_queue_head_t *)done->priv;
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wake_up(wait_q);
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}
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static int erase_write (struct mtd_info *mtd, unsigned long pos,
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int len, const char *buf)
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{
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struct erase_info erase;
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DECLARE_WAITQUEUE(wait, current);
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wait_queue_head_t wait_q;
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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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init_waitqueue_head(&wait_q);
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erase.mtd = mtd;
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erase.callback = erase_callback;
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erase.addr = pos;
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erase.len = len;
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erase.priv = (u_long)&wait_q;
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set_current_state(TASK_INTERRUPTIBLE);
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add_wait_queue(&wait_q, &wait);
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ret = MTD_ERASE(mtd, &erase);
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if (ret) {
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set_current_state(TASK_RUNNING);
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remove_wait_queue(&wait_q, &wait);
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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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schedule(); /* Wait for erase to finish. */
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remove_wait_queue(&wait_q, &wait);
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/*
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* Next, writhe 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->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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DEBUG(MTD_DEBUG_LEVEL2, "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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if (ret)
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return ret;
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/*
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* Here we could argubly 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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mtdblk->cache_state = STATE_EMPTY;
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return 0;
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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->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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DEBUG(MTD_DEBUG_LEVEL2, "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, &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->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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DEBUG(MTD_DEBUG_LEVEL2, "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 = mtdblks[dev->devnum];
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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 = mtdblks[dev->devnum];
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if (unlikely(!mtdblk->cache_data && mtdblk->cache_size)) {
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mtdblk->cache_data = vmalloc(mtdblk->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;
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struct mtd_info *mtd = mbd->mtd;
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int dev = mbd->devnum;
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DEBUG(MTD_DEBUG_LEVEL1,"mtdblock_open\n");
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if (mtdblks[dev]) {
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mtdblks[dev]->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 = kmalloc(sizeof(struct mtdblk_dev), GFP_KERNEL);
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if (!mtdblk)
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return -ENOMEM;
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memset(mtdblk, 0, sizeof(*mtdblk));
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mtdblk->count = 1;
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mtdblk->mtd = mtd;
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init_MUTEX (&mtdblk->cache_sem);
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mtdblk->cache_state = STATE_EMPTY;
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if ((mtdblk->mtd->flags & MTD_CAP_RAM) != MTD_CAP_RAM &&
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mtdblk->mtd->erasesize) {
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mtdblk->cache_size = mtdblk->mtd->erasesize;
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mtdblk->cache_data = NULL;
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}
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mtdblks[dev] = mtdblk;
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DEBUG(MTD_DEBUG_LEVEL1, "ok\n");
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return 0;
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}
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static int mtdblock_release(struct mtd_blktrans_dev *mbd)
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{
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int dev = mbd->devnum;
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struct mtdblk_dev *mtdblk = mtdblks[dev];
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DEBUG(MTD_DEBUG_LEVEL1, "mtdblock_release\n");
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down(&mtdblk->cache_sem);
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write_cached_data(mtdblk);
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up(&mtdblk->cache_sem);
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if (!--mtdblk->count) {
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/* It was the last usage. Free the device */
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mtdblks[dev] = NULL;
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if (mtdblk->mtd->sync)
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mtdblk->mtd->sync(mtdblk->mtd);
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vfree(mtdblk->cache_data);
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kfree(mtdblk);
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}
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DEBUG(MTD_DEBUG_LEVEL1, "ok\n");
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return 0;
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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 = mtdblks[dev->devnum];
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down(&mtdblk->cache_sem);
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write_cached_data(mtdblk);
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up(&mtdblk->cache_sem);
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if (mtdblk->mtd->sync)
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mtdblk->mtd->sync(mtdblk->mtd);
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return 0;
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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 mtd_blktrans_dev *dev = kmalloc(sizeof(*dev), GFP_KERNEL);
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if (!dev)
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return;
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memset(dev, 0, sizeof(*dev));
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dev->mtd = mtd;
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dev->devnum = mtd->index;
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dev->blksize = 512;
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dev->size = mtd->size >> 9;
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dev->tr = tr;
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if (!(mtd->flags & MTD_WRITEABLE))
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dev->readonly = 1;
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add_mtd_blktrans_dev(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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kfree(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 = 31,
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.part_bits = 0,
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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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static int __init init_mtdblock(void)
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{
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return register_mtd_blktrans(&mtdblock_tr);
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}
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static void __exit cleanup_mtdblock(void)
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{
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deregister_mtd_blktrans(&mtdblock_tr);
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}
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module_init(init_mtdblock);
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module_exit(cleanup_mtdblock);
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MODULE_LICENSE("GPL");
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MODULE_AUTHOR("Nicolas Pitre <nico@cam.org> et al.");
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MODULE_DESCRIPTION("Caching read/erase/writeback block device emulation access to MTD devices");
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Reference in New Issue
Block a user