[PATCH 1/4] add block support
Sascha Hauer
s.hauer at pengutronix.de
Fri Apr 8 10:48:33 EDT 2011
This adds a simple block layer to barebox. Reading and writing
to block devices can be painfully slow without caching, so
add a simple caching layer here.
Signed-off-by: Sascha Hauer <s.hauer at pengutronix.de>
---
common/Kconfig | 6 ++
common/Makefile | 1 +
common/block.c | 263 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
fs/Makefile | 2 +-
include/block.h | 32 +++++++
5 files changed, 303 insertions(+), 1 deletions(-)
create mode 100644 common/block.c
create mode 100644 include/block.h
diff --git a/common/Kconfig b/common/Kconfig
index 9e30579..ac83231 100644
--- a/common/Kconfig
+++ b/common/Kconfig
@@ -31,6 +31,12 @@ config ENV_HANDLING
config GENERIC_GPIO
bool
+config BLOCK
+ bool
+
+config BLOCK_WRITE
+ bool
+
menu "General Settings "
config LOCALVERSION_AUTO
diff --git a/common/Makefile b/common/Makefile
index d8c302f..3fc66f4 100644
--- a/common/Makefile
+++ b/common/Makefile
@@ -6,6 +6,7 @@ obj-$(CONFIG_KALLSYMS) += kallsyms.o
obj-$(CONFIG_ENV_HANDLING) += environment.o
obj-$(CONFIG_AUTO_COMPLETE) += complete.o
obj-$(CONFIG_POLLER) += poller.o
+obj-$(CONFIG_BLOCK) += block.o
obj-y += dlmalloc.o
obj-y += clock.o
diff --git a/common/block.c b/common/block.c
new file mode 100644
index 0000000..24377c6
--- /dev/null
+++ b/common/block.c
@@ -0,0 +1,263 @@
+/*
+ * block.c - simple block layer
+ *
+ * Copyright (c) 2011 Sascha Hauer <s.hauer at 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;
+}
+
diff --git a/fs/Makefile b/fs/Makefile
index 4aa92ef..9e97db3 100644
--- a/fs/Makefile
+++ b/fs/Makefile
@@ -2,4 +2,4 @@ obj-$(CONFIG_FS_CRAMFS) += cramfs/
obj-$(CONFIG_FS_RAMFS) += ramfs.o
obj-y += devfs-core.o
obj-$(CONFIG_FS_DEVFS) += devfs.o
-obj-y += fs.o
+obj-$(CONFIG_FS_FAT) += fat/
diff --git a/include/block.h b/include/block.h
new file mode 100644
index 0000000..aaab4e3
--- /dev/null
+++ b/include/block.h
@@ -0,0 +1,32 @@
+#ifndef __BLOCK_H
+#define __BLOCK_H
+
+#include <driver.h>
+
+struct block_device;
+
+struct block_device_ops {
+ int (*read)(struct block_device *, void *buf, int block, int num_blocks);
+ int (*write)(struct block_device *, const void *buf, int block, int num_blocks);
+};
+
+struct block_device {
+ struct device_d *dev;
+ struct block_device_ops *ops;
+ int blockbits;
+ int num_blocks;
+ void *rdbuf; /* read buffer */
+ int rdbufsize;
+ int rdblock; /* start block in read buffer */
+ int rdblockend; /* end block in read buffer */
+ void *wrbuf; /* write buffer */
+ int wrblock; /* start block in write buffer */
+ int wrbufblocks; /* number of blocks currently in write buffer */
+ int wrbufsize; /* size of write buffer in blocks */
+ struct cdev cdev;
+};
+
+int blockdevice_register(struct block_device *blk);
+int blockdevice_unregister(struct block_device *blk);
+
+#endif /* __BLOCK_H */
--
1.7.2.3
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