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authorLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
commit1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch)
tree0bba044c4ce775e45a88a51686b5d9f90697ea9d /drivers/mtd/mtdblock.c
downloadlinaro-lsk-1da177e4c3f41524e886b7f1b8a0c1fc7321cac2.tar.gz
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!
Diffstat (limited to 'drivers/mtd/mtdblock.c')
-rw-r--r--drivers/mtd/mtdblock.c394
1 files changed, 394 insertions, 0 deletions
diff --git a/drivers/mtd/mtdblock.c b/drivers/mtd/mtdblock.c
new file mode 100644
index 00000000000..b7c32c242bc
--- /dev/null
+++ b/drivers/mtd/mtdblock.c
@@ -0,0 +1,394 @@
+/*
+ * Direct MTD block device access
+ *
+ * $Id: mtdblock.c,v 1.66 2004/11/25 13:52:52 joern Exp $
+ *
+ * (C) 2000-2003 Nicolas Pitre <nico@cam.org>
+ * (C) 1999-2003 David Woodhouse <dwmw2@infradead.org>
+ */
+
+#include <linux/config.h>
+#include <linux/types.h>
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/fs.h>
+#include <linux/init.h>
+#include <linux/slab.h>
+#include <linux/vmalloc.h>
+#include <linux/mtd/mtd.h>
+#include <linux/mtd/blktrans.h>
+
+static struct mtdblk_dev {
+ struct mtd_info *mtd;
+ int count;
+ struct semaphore cache_sem;
+ unsigned char *cache_data;
+ unsigned long cache_offset;
+ unsigned int cache_size;
+ enum { STATE_EMPTY, STATE_CLEAN, STATE_DIRTY } cache_state;
+} *mtdblks[MAX_MTD_DEVICES];
+
+/*
+ * Cache stuff...
+ *
+ * Since typical flash erasable sectors are much larger than what Linux's
+ * buffer cache can handle, we must implement read-modify-write on flash
+ * sectors for each block write requests. To avoid over-erasing flash sectors
+ * and to speed things up, we locally cache a whole flash sector while it is
+ * being written to until a different sector is required.
+ */
+
+static void erase_callback(struct erase_info *done)
+{
+ wait_queue_head_t *wait_q = (wait_queue_head_t *)done->priv;
+ wake_up(wait_q);
+}
+
+static int erase_write (struct mtd_info *mtd, unsigned long pos,
+ int len, const char *buf)
+{
+ struct erase_info erase;
+ DECLARE_WAITQUEUE(wait, current);
+ wait_queue_head_t wait_q;
+ size_t retlen;
+ int ret;
+
+ /*
+ * First, let's erase the flash block.
+ */
+
+ init_waitqueue_head(&wait_q);
+ erase.mtd = mtd;
+ erase.callback = erase_callback;
+ erase.addr = pos;
+ erase.len = len;
+ erase.priv = (u_long)&wait_q;
+
+ set_current_state(TASK_INTERRUPTIBLE);
+ add_wait_queue(&wait_q, &wait);
+
+ ret = MTD_ERASE(mtd, &erase);
+ if (ret) {
+ set_current_state(TASK_RUNNING);
+ remove_wait_queue(&wait_q, &wait);
+ printk (KERN_WARNING "mtdblock: erase of region [0x%lx, 0x%x] "
+ "on \"%s\" failed\n",
+ pos, len, mtd->name);
+ return ret;
+ }
+
+ schedule(); /* Wait for erase to finish. */
+ remove_wait_queue(&wait_q, &wait);
+
+ /*
+ * Next, writhe data to flash.
+ */
+
+ ret = MTD_WRITE (mtd, pos, len, &retlen, buf);
+ if (ret)
+ return ret;
+ if (retlen != len)
+ return -EIO;
+ return 0;
+}
+
+
+static int write_cached_data (struct mtdblk_dev *mtdblk)
+{
+ struct mtd_info *mtd = mtdblk->mtd;
+ int ret;
+
+ if (mtdblk->cache_state != STATE_DIRTY)
+ return 0;
+
+ DEBUG(MTD_DEBUG_LEVEL2, "mtdblock: writing cached data for \"%s\" "
+ "at 0x%lx, size 0x%x\n", mtd->name,
+ mtdblk->cache_offset, mtdblk->cache_size);
+
+ ret = erase_write (mtd, mtdblk->cache_offset,
+ mtdblk->cache_size, mtdblk->cache_data);
+ if (ret)
+ return ret;
+
+ /*
+ * Here we could argubly set the cache state to STATE_CLEAN.
+ * However this could lead to inconsistency since we will not
+ * be notified if this content is altered on the flash by other
+ * means. Let's declare it empty and leave buffering tasks to
+ * the buffer cache instead.
+ */
+ mtdblk->cache_state = STATE_EMPTY;
+ return 0;
+}
+
+
+static int do_cached_write (struct mtdblk_dev *mtdblk, unsigned long pos,
+ int len, const char *buf)
+{
+ struct mtd_info *mtd = mtdblk->mtd;
+ unsigned int sect_size = mtdblk->cache_size;
+ size_t retlen;
+ int ret;
+
+ DEBUG(MTD_DEBUG_LEVEL2, "mtdblock: write on \"%s\" at 0x%lx, size 0x%x\n",
+ mtd->name, pos, len);
+
+ if (!sect_size)
+ return MTD_WRITE (mtd, pos, len, &retlen, buf);
+
+ while (len > 0) {
+ unsigned long sect_start = (pos/sect_size)*sect_size;
+ unsigned int offset = pos - sect_start;
+ unsigned int size = sect_size - offset;
+ if( size > len )
+ size = len;
+
+ if (size == sect_size) {
+ /*
+ * We are covering a whole sector. Thus there is no
+ * need to bother with the cache while it may still be
+ * useful for other partial writes.
+ */
+ ret = erase_write (mtd, pos, size, buf);
+ if (ret)
+ return ret;
+ } else {
+ /* Partial sector: need to use the cache */
+
+ if (mtdblk->cache_state == STATE_DIRTY &&
+ mtdblk->cache_offset != sect_start) {
+ ret = write_cached_data(mtdblk);
+ if (ret)
+ return ret;
+ }
+
+ if (mtdblk->cache_state == STATE_EMPTY ||
+ mtdblk->cache_offset != sect_start) {
+ /* fill the cache with the current sector */
+ mtdblk->cache_state = STATE_EMPTY;
+ ret = MTD_READ(mtd, sect_start, sect_size, &retlen, mtdblk->cache_data);
+ if (ret)
+ return ret;
+ if (retlen != sect_size)
+ return -EIO;
+
+ mtdblk->cache_offset = sect_start;
+ mtdblk->cache_size = sect_size;
+ mtdblk->cache_state = STATE_CLEAN;
+ }
+
+ /* write data to our local cache */
+ memcpy (mtdblk->cache_data + offset, buf, size);
+ mtdblk->cache_state = STATE_DIRTY;
+ }
+
+ buf += size;
+ pos += size;
+ len -= size;
+ }
+
+ return 0;
+}
+
+
+static int do_cached_read (struct mtdblk_dev *mtdblk, unsigned long pos,
+ int len, char *buf)
+{
+ struct mtd_info *mtd = mtdblk->mtd;
+ unsigned int sect_size = mtdblk->cache_size;
+ size_t retlen;
+ int ret;
+
+ DEBUG(MTD_DEBUG_LEVEL2, "mtdblock: read on \"%s\" at 0x%lx, size 0x%x\n",
+ mtd->name, pos, len);
+
+ if (!sect_size)
+ return MTD_READ (mtd, pos, len, &retlen, buf);
+
+ while (len > 0) {
+ unsigned long sect_start = (pos/sect_size)*sect_size;
+ unsigned int offset = pos - sect_start;
+ unsigned int size = sect_size - offset;
+ if (size > len)
+ size = len;
+
+ /*
+ * Check if the requested data is already cached
+ * Read the requested amount of data from our internal cache if it
+ * contains what we want, otherwise we read the data directly
+ * from flash.
+ */
+ if (mtdblk->cache_state != STATE_EMPTY &&
+ mtdblk->cache_offset == sect_start) {
+ memcpy (buf, mtdblk->cache_data + offset, size);
+ } else {
+ ret = MTD_READ (mtd, pos, size, &retlen, buf);
+ if (ret)
+ return ret;
+ if (retlen != size)
+ return -EIO;
+ }
+
+ buf += size;
+ pos += size;
+ len -= size;
+ }
+
+ return 0;
+}
+
+static int mtdblock_readsect(struct mtd_blktrans_dev *dev,
+ unsigned long block, char *buf)
+{
+ struct mtdblk_dev *mtdblk = mtdblks[dev->devnum];
+ return do_cached_read(mtdblk, block<<9, 512, buf);
+}
+
+static int mtdblock_writesect(struct mtd_blktrans_dev *dev,
+ unsigned long block, char *buf)
+{
+ struct mtdblk_dev *mtdblk = mtdblks[dev->devnum];
+ if (unlikely(!mtdblk->cache_data && mtdblk->cache_size)) {
+ mtdblk->cache_data = vmalloc(mtdblk->mtd->erasesize);
+ if (!mtdblk->cache_data)
+ return -EINTR;
+ /* -EINTR is not really correct, but it is the best match
+ * documented in man 2 write for all cases. We could also
+ * return -EAGAIN sometimes, but why bother?
+ */
+ }
+ return do_cached_write(mtdblk, block<<9, 512, buf);
+}
+
+static int mtdblock_open(struct mtd_blktrans_dev *mbd)
+{
+ struct mtdblk_dev *mtdblk;
+ struct mtd_info *mtd = mbd->mtd;
+ int dev = mbd->devnum;
+
+ DEBUG(MTD_DEBUG_LEVEL1,"mtdblock_open\n");
+
+ if (mtdblks[dev]) {
+ mtdblks[dev]->count++;
+ return 0;
+ }
+
+ /* OK, it's not open. Create cache info for it */
+ mtdblk = kmalloc(sizeof(struct mtdblk_dev), GFP_KERNEL);
+ if (!mtdblk)
+ return -ENOMEM;
+
+ memset(mtdblk, 0, sizeof(*mtdblk));
+ mtdblk->count = 1;
+ mtdblk->mtd = mtd;
+
+ init_MUTEX (&mtdblk->cache_sem);
+ mtdblk->cache_state = STATE_EMPTY;
+ if ((mtdblk->mtd->flags & MTD_CAP_RAM) != MTD_CAP_RAM &&
+ mtdblk->mtd->erasesize) {
+ mtdblk->cache_size = mtdblk->mtd->erasesize;
+ mtdblk->cache_data = NULL;
+ }
+
+ mtdblks[dev] = mtdblk;
+
+ DEBUG(MTD_DEBUG_LEVEL1, "ok\n");
+
+ return 0;
+}
+
+static int mtdblock_release(struct mtd_blktrans_dev *mbd)
+{
+ int dev = mbd->devnum;
+ struct mtdblk_dev *mtdblk = mtdblks[dev];
+
+ DEBUG(MTD_DEBUG_LEVEL1, "mtdblock_release\n");
+
+ down(&mtdblk->cache_sem);
+ write_cached_data(mtdblk);
+ up(&mtdblk->cache_sem);
+
+ if (!--mtdblk->count) {
+ /* It was the last usage. Free the device */
+ mtdblks[dev] = NULL;
+ if (mtdblk->mtd->sync)
+ mtdblk->mtd->sync(mtdblk->mtd);
+ vfree(mtdblk->cache_data);
+ kfree(mtdblk);
+ }
+ DEBUG(MTD_DEBUG_LEVEL1, "ok\n");
+
+ return 0;
+}
+
+static int mtdblock_flush(struct mtd_blktrans_dev *dev)
+{
+ struct mtdblk_dev *mtdblk = mtdblks[dev->devnum];
+
+ down(&mtdblk->cache_sem);
+ write_cached_data(mtdblk);
+ up(&mtdblk->cache_sem);
+
+ if (mtdblk->mtd->sync)
+ mtdblk->mtd->sync(mtdblk->mtd);
+ return 0;
+}
+
+static void mtdblock_add_mtd(struct mtd_blktrans_ops *tr, struct mtd_info *mtd)
+{
+ struct mtd_blktrans_dev *dev = kmalloc(sizeof(*dev), GFP_KERNEL);
+
+ if (!dev)
+ return;
+
+ memset(dev, 0, sizeof(*dev));
+
+ dev->mtd = mtd;
+ dev->devnum = mtd->index;
+ dev->blksize = 512;
+ dev->size = mtd->size >> 9;
+ dev->tr = tr;
+
+ if (!(mtd->flags & MTD_WRITEABLE))
+ dev->readonly = 1;
+
+ add_mtd_blktrans_dev(dev);
+}
+
+static void mtdblock_remove_dev(struct mtd_blktrans_dev *dev)
+{
+ del_mtd_blktrans_dev(dev);
+ kfree(dev);
+}
+
+static struct mtd_blktrans_ops mtdblock_tr = {
+ .name = "mtdblock",
+ .major = 31,
+ .part_bits = 0,
+ .open = mtdblock_open,
+ .flush = mtdblock_flush,
+ .release = mtdblock_release,
+ .readsect = mtdblock_readsect,
+ .writesect = mtdblock_writesect,
+ .add_mtd = mtdblock_add_mtd,
+ .remove_dev = mtdblock_remove_dev,
+ .owner = THIS_MODULE,
+};
+
+static int __init init_mtdblock(void)
+{
+ return register_mtd_blktrans(&mtdblock_tr);
+}
+
+static void __exit cleanup_mtdblock(void)
+{
+ deregister_mtd_blktrans(&mtdblock_tr);
+}
+
+module_init(init_mtdblock);
+module_exit(cleanup_mtdblock);
+
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Nicolas Pitre <nico@cam.org> et al.");
+MODULE_DESCRIPTION("Caching read/erase/writeback block device emulation access to MTD devices");