| /* |
| * 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/sched.h> /* TASK_* */ |
| #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"); |