1 files changed, 394 insertions, 0 deletions

diff --git a/drivers/mtd/mtdblock.c b/drivers/mtd/mtdblock.c
new file mode 100644
index 000000000000..b7c32c242bc7
--- /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");