diff options
Diffstat (limited to 'common/block.c')
| -rw-r--r-- | common/block.c | 263 |
1 files changed, 263 insertions, 0 deletions
diff --git a/common/block.c b/common/block.c new file mode 100644 index 0000000000..24377c627d --- /dev/null +++ b/common/block.c @@ -0,0 +1,263 @@ +/* + * block.c - simple block layer + * + * Copyright (c) 2011 Sascha Hauer <s.hauer@pengutronix.de>, Pengutronix + * + * See file CREDITS for list of people who contributed to this + * project. + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 + * as published by the Free Software Foundation. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA + */ +#include <common.h> +#include <block.h> +#include <linux/err.h> + +#define BLOCKSIZE(blk) (1 << blk->blockbits) + +#define WRBUFFER_LAST(blk) (blk->wrblock + blk->wrbufblocks - 1) + +#ifdef CONFIG_BLOCK_WRITE +static int writebuffer_flush(struct block_device *blk) +{ + if (!blk->wrbufblocks) + return 0; + + blk->ops->write(blk, blk->wrbuf, blk->wrblock, + blk->wrbufblocks); + + blk->wrbufblocks = 0; + + return 0; +} + +static int block_put(struct block_device *blk, const void *buf, int block) +{ + if (block >= blk->num_blocks) + return -EIO; + + if (block < blk->wrblock || block > blk->wrblock + blk->wrbufblocks) { + writebuffer_flush(blk); + } + + if (blk->wrbufblocks == 0) { + blk->wrblock = block; + blk->wrbufblocks = 1; + } + + memcpy(blk->wrbuf + (block - blk->wrblock) * BLOCKSIZE(blk), + buf, BLOCKSIZE(blk)); + + if (block > WRBUFFER_LAST(blk)) + blk->wrbufblocks++; + + if (blk->wrbufblocks == blk->wrbufsize) + writebuffer_flush(blk); + + return 0; +} + +#else +static int writebuffer_flush(struct block_device *blk) +{ + return 0; +} +#endif + +static void *block_get(struct block_device *blk, int block) +{ + int ret; + int num_blocks; + + if (block >= blk->num_blocks) + return ERR_PTR(-EIO); + + /* first look into write buffer */ + if (block >= blk->wrblock && block <= WRBUFFER_LAST(blk)) + return blk->wrbuf + (block - blk->wrblock) * BLOCKSIZE(blk); + + /* then look into read buffer */ + if (block >= blk->rdblock && block <= blk->rdblockend) + return blk->rdbuf + (block - blk->rdblock) * BLOCKSIZE(blk); + + /* + * If none of the buffers above match read the block from + * the device + */ + num_blocks = min(blk->rdbufsize, blk->num_blocks - block); + + ret = blk->ops->read(blk, blk->rdbuf, block, num_blocks); + if (ret) + return ERR_PTR(ret); + + blk->rdblock = block; + blk->rdblockend = block + num_blocks - 1; + + return blk->rdbuf; +} + +static ssize_t block_read(struct cdev *cdev, void *buf, size_t count, + unsigned long offset, unsigned long flags) +{ + struct block_device *blk = cdev->priv; + unsigned long mask = BLOCKSIZE(blk) - 1; + unsigned long block = offset >> blk->blockbits; + size_t icount = count; + int blocks; + + if (offset & mask) { + size_t now = BLOCKSIZE(blk) - (offset & mask); + void *iobuf = block_get(blk, block); + + now = min(count, now); + + if (IS_ERR(iobuf)) + return PTR_ERR(iobuf); + + memcpy(buf, iobuf + (offset & mask), now); + buf += now; + count -= now; + block++; + } + + blocks = count >> blk->blockbits; + + while (blocks) { + void *iobuf = block_get(blk, block); + + if (IS_ERR(iobuf)) + return PTR_ERR(iobuf); + + memcpy(buf, iobuf, BLOCKSIZE(blk)); + buf += BLOCKSIZE(blk); + blocks--; + block++; + count -= BLOCKSIZE(blk); + } + + if (count) { + void *iobuf = block_get(blk, block); + + if (IS_ERR(iobuf)) + return PTR_ERR(iobuf); + + memcpy(buf, iobuf, count); + } + + return icount; +} + +#ifdef CONFIG_BLOCK_WRITE +static ssize_t block_write(struct cdev *cdev, const void *buf, size_t count, + unsigned long offset, ulong flags) +{ + struct block_device *blk = cdev->priv; + unsigned long mask = BLOCKSIZE(blk) - 1; + unsigned long block = offset >> blk->blockbits; + size_t icount = count; + int blocks; + + if (offset & mask) { + size_t now = BLOCKSIZE(blk) - (offset & mask); + void *iobuf = block_get(blk, block); + + now = min(count, now); + + if (IS_ERR(iobuf)) + return PTR_ERR(iobuf); + + memcpy(iobuf + (offset & mask), buf, now); + block_put(blk, iobuf, block); + buf += now; + count -= now; + block++; + } + + blocks = count >> blk->blockbits; + + while (blocks) { + block_put(blk, buf, block); + buf += BLOCKSIZE(blk); + blocks--; + block++; + count -= BLOCKSIZE(blk); + } + + if (count) { + void *iobuf = block_get(blk, block); + + if (IS_ERR(iobuf)) + return PTR_ERR(iobuf); + + memcpy(iobuf, buf, count); + block_put(blk, iobuf, block); + } + + return icount; +} +#endif + +static int block_close(struct cdev *cdev) +{ + struct block_device *blk = cdev->priv; + + return writebuffer_flush(blk); +} + +static int block_flush(struct cdev *cdev) +{ + struct block_device *blk = cdev->priv; + + return writebuffer_flush(blk); +} + +struct file_operations block_ops = { + .read = block_read, +#ifdef CONFIG_BLOCK_WRITE + .write = block_write, +#endif + .close = block_close, + .flush = block_flush, + .lseek = dev_lseek_default, +}; + +int blockdevice_register(struct block_device *blk) +{ + size_t size = blk->num_blocks * BLOCKSIZE(blk); + int ret; + + blk->cdev.size = size; + blk->cdev.dev = blk->dev; + blk->cdev.ops = &block_ops; + blk->cdev.priv = blk; + blk->rdbufsize = PAGE_SIZE >> blk->blockbits; + blk->rdbuf = xmalloc(PAGE_SIZE); + blk->rdblock = 1; + blk->rdblockend = 0; + blk->wrbufsize = PAGE_SIZE >> blk->blockbits; + blk->wrbuf = xmalloc(PAGE_SIZE); + blk->wrblock = 0; + blk->wrbufblocks = 0; + + ret = devfs_create(&blk->cdev); + if (ret) + return ret; + + return 0; +} + +int blockdevice_unregister(struct block_device *blk) +{ + return 0; +} + |