From 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Sat, 16 Apr 2005 15:20:36 -0700 Subject: 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! --- drivers/mtd/mtdblock.c | 394 +++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 394 insertions(+) create mode 100644 drivers/mtd/mtdblock.c (limited to 'drivers/mtd/mtdblock.c') 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 + * (C) 1999-2003 David Woodhouse + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +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 et al."); +MODULE_DESCRIPTION("Caching read/erase/writeback block device emulation access to MTD devices"); -- cgit v1.2.3