Merge pull request #597 from hzhuang1/emmc_v3.2

Emmc v3

2 files changed, 759 insertions, 0 deletions

diff --git a/drivers/emmc/emmc.c b/drivers/emmc/emmc.c
new file mode 100644
index 00000000..5fe28efc
--- /dev/null
+++ b/drivers/emmc/emmc.c
@@ -0,0 +1,347 @@
+/*
+ * Copyright (c) 2016, ARM Limited and Contributors. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * Redistributions of source code must retain the above copyright notice, this
+ * list of conditions and the following disclaimer.
+ *
+ * Redistributions in binary form must reproduce the above copyright notice,
+ * this list of conditions and the following disclaimer in the documentation
+ * and/or other materials provided with the distribution.
+ *
+ * Neither the name of ARM nor the names of its contributors may be used
+ * to endorse or promote products derived from this software without specific
+ * prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ * Defines a simple and generic interface to access eMMC device.
+ */
+
+#include <arch_helpers.h>
+#include <assert.h>
+#include <debug.h>
+#include <emmc.h>
+#include <errno.h>
+#include <string.h>
+
+static const emmc_ops_t *ops;
+static unsigned int emmc_ocr_value;
+static emmc_csd_t emmc_csd;
+
+static int emmc_device_state(void)
+{
+	emmc_cmd_t cmd;
+	int ret;
+
+	do {
+		memset(&cmd, 0, sizeof(emmc_cmd_t));
+		cmd.cmd_idx = EMMC_CMD13;
+		cmd.cmd_arg = EMMC_FIX_RCA << RCA_SHIFT_OFFSET;
+		cmd.resp_type = EMMC_RESPONSE_R1;
+		ret = ops->send_cmd(&cmd);
+		assert(ret == 0);
+		assert((cmd.resp_data[0] & STATUS_SWITCH_ERROR) == 0);
+		/* Ignore improbable errors in release builds */
+		(void)ret;
+	} while ((cmd.resp_data[0] & STATUS_READY_FOR_DATA) == 0);
+	return EMMC_GET_STATE(cmd.resp_data[0]);
+}
+
+static void emmc_set_ext_csd(unsigned int ext_cmd, unsigned int value)
+{
+	emmc_cmd_t cmd;
+	int ret, state;
+
+	memset(&cmd, 0, sizeof(emmc_cmd_t));
+	cmd.cmd_idx = EMMC_CMD6;
+	cmd.cmd_arg = EXTCSD_WRITE_BYTES | EXTCSD_CMD(ext_cmd) |
+		      EXTCSD_VALUE(value) | 1;
+	ret = ops->send_cmd(&cmd);
+	assert(ret == 0);
+
+	/* wait to exit PRG state */
+	do {
+		state = emmc_device_state();
+	} while (state == EMMC_STATE_PRG);
+	/* Ignore improbable errors in release builds */
+	(void)ret;
+}
+
+static void emmc_set_ios(int clk, int bus_width)
+{
+	int ret;
+
+	/* set IO speed & IO bus width */
+	if (emmc_csd.spec_vers == 4)
+		emmc_set_ext_csd(CMD_EXTCSD_BUS_WIDTH, bus_width);
+	ret = ops->set_ios(clk, bus_width);
+	assert(ret == 0);
+	/* Ignore improbable errors in release builds */
+	(void)ret;
+}
+
+static int emmc_enumerate(int clk, int bus_width)
+{
+	emmc_cmd_t cmd;
+	int ret, state;
+
+	ops->init();
+
+	/* CMD0: reset to IDLE */
+	memset(&cmd, 0, sizeof(emmc_cmd_t));
+	cmd.cmd_idx = EMMC_CMD0;
+	ret = ops->send_cmd(&cmd);
+	assert(ret == 0);
+
+	while (1) {
+		/* CMD1: get OCR register */
+		memset(&cmd, 0, sizeof(emmc_cmd_t));
+		cmd.cmd_idx = EMMC_CMD1;
+		cmd.cmd_arg = OCR_SECTOR_MODE | OCR_VDD_MIN_2V7 |
+			      OCR_VDD_MIN_1V7;
+		cmd.resp_type = EMMC_RESPONSE_R3;
+		ret = ops->send_cmd(&cmd);
+		assert(ret == 0);
+		emmc_ocr_value = cmd.resp_data[0];
+		if (emmc_ocr_value & OCR_POWERUP)
+			break;
+	}
+
+	/* CMD2: Card Identification */
+	memset(&cmd, 0, sizeof(emmc_cmd_t));
+	cmd.cmd_idx = EMMC_CMD2;
+	cmd.resp_type = EMMC_RESPONSE_R2;
+	ret = ops->send_cmd(&cmd);
+	assert(ret == 0);
+
+	/* CMD3: Set Relative Address */
+	memset(&cmd, 0, sizeof(emmc_cmd_t));
+	cmd.cmd_idx = EMMC_CMD3;
+	cmd.cmd_arg = EMMC_FIX_RCA << RCA_SHIFT_OFFSET;
+	cmd.resp_type = EMMC_RESPONSE_R1;
+	ret = ops->send_cmd(&cmd);
+	assert(ret == 0);
+
+	/* CMD9: CSD Register */
+	memset(&cmd, 0, sizeof(emmc_cmd_t));
+	cmd.cmd_idx = EMMC_CMD9;
+	cmd.cmd_arg = EMMC_FIX_RCA << RCA_SHIFT_OFFSET;
+	cmd.resp_type = EMMC_RESPONSE_R2;
+	ret = ops->send_cmd(&cmd);
+	assert(ret == 0);
+	memcpy(&emmc_csd, &cmd.resp_data, sizeof(cmd.resp_data));
+
+	/* CMD7: Select Card */
+	memset(&cmd, 0, sizeof(emmc_cmd_t));
+	cmd.cmd_idx = EMMC_CMD7;
+	cmd.cmd_arg = EMMC_FIX_RCA << RCA_SHIFT_OFFSET;
+	cmd.resp_type = EMMC_RESPONSE_R1;
+	ret = ops->send_cmd(&cmd);
+	assert(ret == 0);
+	/* wait to TRAN state */
+	do {
+		state = emmc_device_state();
+	} while (state != EMMC_STATE_TRAN);
+
+	emmc_set_ios(clk, bus_width);
+	return ret;
+}
+
+size_t emmc_read_blocks(int lba, uintptr_t buf, size_t size)
+{
+	emmc_cmd_t cmd;
+	int ret;
+
+	assert((ops != 0) &&
+	       (ops->read != 0) &&
+	       ((buf & EMMC_BLOCK_MASK) == 0) &&
+	       ((size & EMMC_BLOCK_MASK) == 0));
+
+	inv_dcache_range(buf, size);
+	ret = ops->prepare(lba, buf, size);
+	assert(ret == 0);
+
+	memset(&cmd, 0, sizeof(emmc_cmd_t));
+	if (size > EMMC_BLOCK_SIZE)
+		cmd.cmd_idx = EMMC_CMD18;
+	else
+		cmd.cmd_idx = EMMC_CMD17;
+	if ((emmc_ocr_value & OCR_ACCESS_MODE_MASK) == OCR_BYTE_MODE)
+		cmd.cmd_arg = lba * EMMC_BLOCK_SIZE;
+	else
+		cmd.cmd_arg = lba;
+	cmd.resp_type = EMMC_RESPONSE_R1;
+	ret = ops->send_cmd(&cmd);
+	assert(ret == 0);
+
+	ret = ops->read(lba, buf, size);
+	assert(ret == 0);
+
+	/* wait buffer empty */
+	emmc_device_state();
+
+	if (size > EMMC_BLOCK_SIZE) {
+		memset(&cmd, 0, sizeof(emmc_cmd_t));
+		cmd.cmd_idx = EMMC_CMD12;
+		ret = ops->send_cmd(&cmd);
+		assert(ret == 0);
+	}
+	/* Ignore improbable errors in release builds */
+	(void)ret;
+	return size;
+}
+
+size_t emmc_write_blocks(int lba, const uintptr_t buf, size_t size)
+{
+	emmc_cmd_t cmd;
+	int ret;
+
+	assert((ops != 0) &&
+	       (ops->write != 0) &&
+	       ((buf & EMMC_BLOCK_MASK) == 0) &&
+	       ((size & EMMC_BLOCK_MASK) == 0));
+
+	clean_dcache_range(buf, size);
+	ret = ops->prepare(lba, buf, size);
+	assert(ret == 0);
+
+	memset(&cmd, 0, sizeof(emmc_cmd_t));
+	if (size > EMMC_BLOCK_SIZE)
+		cmd.cmd_idx = EMMC_CMD25;
+	else
+		cmd.cmd_idx = EMMC_CMD24;
+	if ((emmc_ocr_value & OCR_ACCESS_MODE_MASK) == OCR_BYTE_MODE)
+		cmd.cmd_arg = lba * EMMC_BLOCK_SIZE;
+	else
+		cmd.cmd_arg = lba;
+	cmd.resp_type = EMMC_RESPONSE_R1;
+	ret = ops->send_cmd(&cmd);
+	assert(ret == 0);
+
+	ret = ops->write(lba, buf, size);
+	assert(ret == 0);
+
+	/* wait buffer empty */
+	emmc_device_state();
+
+	if (size > EMMC_BLOCK_SIZE) {
+		memset(&cmd, 0, sizeof(emmc_cmd_t));
+		cmd.cmd_idx = EMMC_CMD12;
+		ret = ops->send_cmd(&cmd);
+		assert(ret == 0);
+	}
+	/* Ignore improbable errors in release builds */
+	(void)ret;
+	return size;
+}
+
+size_t emmc_erase_blocks(int lba, size_t size)
+{
+	emmc_cmd_t cmd;
+	int ret, state;
+
+	assert(ops != 0);
+	assert((size != 0) && ((size % EMMC_BLOCK_SIZE) == 0));
+
+	memset(&cmd, 0, sizeof(emmc_cmd_t));
+	cmd.cmd_idx = EMMC_CMD35;
+	cmd.cmd_arg = lba;
+	cmd.resp_type = EMMC_RESPONSE_R1;
+	ret = ops->send_cmd(&cmd);
+	assert(ret == 0);
+
+	memset(&cmd, 0, sizeof(emmc_cmd_t));
+	cmd.cmd_idx = EMMC_CMD36;
+	cmd.cmd_arg = lba + (size / EMMC_BLOCK_SIZE) - 1;
+	cmd.resp_type = EMMC_RESPONSE_R1;
+	ret = ops->send_cmd(&cmd);
+	assert(ret == 0);
+
+	memset(&cmd, 0, sizeof(emmc_cmd_t));
+	cmd.cmd_idx = EMMC_CMD38;
+	cmd.resp_type = EMMC_RESPONSE_R1B;
+	ret = ops->send_cmd(&cmd);
+	assert(ret == 0);
+
+	/* wait to TRAN state */
+	do {
+		state = emmc_device_state();
+	} while (state != EMMC_STATE_TRAN);
+	/* Ignore improbable errors in release builds */
+	(void)ret;
+	return size;
+}
+
+static inline void emmc_rpmb_enable(void)
+{
+	emmc_set_ext_csd(CMD_EXTCSD_PARTITION_CONFIG,
+			PART_CFG_BOOT_PARTITION1_ENABLE |
+			PART_CFG_PARTITION1_ACCESS);
+}
+
+static inline void emmc_rpmb_disable(void)
+{
+	emmc_set_ext_csd(CMD_EXTCSD_PARTITION_CONFIG,
+			PART_CFG_BOOT_PARTITION1_ENABLE);
+}
+
+size_t emmc_rpmb_read_blocks(int lba, uintptr_t buf, size_t size)
+{
+	size_t size_read;
+
+	emmc_rpmb_enable();
+	size_read = emmc_read_blocks(lba, buf, size);
+	emmc_rpmb_disable();
+	return size_read;
+}
+
+size_t emmc_rpmb_write_blocks(int lba, const uintptr_t buf, size_t size)
+{
+	size_t size_written;
+
+	emmc_rpmb_enable();
+	size_written = emmc_write_blocks(lba, buf, size);
+	emmc_rpmb_disable();
+	return size_written;
+}
+
+size_t emmc_rpmb_erase_blocks(int lba, size_t size)
+{
+	size_t size_erased;
+
+	emmc_rpmb_enable();
+	size_erased = emmc_erase_blocks(lba, size);
+	emmc_rpmb_disable();
+	return size_erased;
+}
+
+void emmc_init(const emmc_ops_t *ops_ptr, int clk, int width)
+{
+	assert((ops_ptr != 0) &&
+	       (ops_ptr->init != 0) &&
+	       (ops_ptr->send_cmd != 0) &&
+	       (ops_ptr->set_ios != 0) &&
+	       (ops_ptr->prepare != 0) &&
+	       (ops_ptr->read != 0) &&
+	       (ops_ptr->write != 0) &&
+	       (clk != 0) &&
+	       ((width == EMMC_BUS_WIDTH_1) ||
+		(width == EMMC_BUS_WIDTH_4) ||
+		(width == EMMC_BUS_WIDTH_8)));
+	ops = ops_ptr;
+
+	emmc_enumerate(clk, width);
+}
diff --git a/drivers/io/io_block.c b/drivers/io/io_block.c
new file mode 100644
index 00000000..198b723b
--- /dev/null
+++ b/drivers/io/io_block.c
@@ -0,0 +1,412 @@
+/*
+ * Copyright (c) 2016, ARM Limited and Contributors. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * Redistributions of source code must retain the above copyright notice, this
+ * list of conditions and the following disclaimer.
+ *
+ * Redistributions in binary form must reproduce the above copyright notice,
+ * this list of conditions and the following disclaimer in the documentation
+ * and/or other materials provided with the distribution.
+ *
+ * Neither the name of ARM nor the names of its contributors may be used
+ * to endorse or promote products derived from this software without specific
+ * prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <assert.h>
+#include <debug.h>
+#include <errno.h>
+#include <io_block.h>
+#include <io_driver.h>
+#include <io_storage.h>
+#include <platform_def.h>
+#include <string.h>
+
+typedef struct {
+	io_block_dev_spec_t	*dev_spec;
+	uintptr_t		base;
+	size_t			file_pos;
+	size_t			size;
+} block_dev_state_t;
+
+#define is_power_of_2(x)	((x != 0) && ((x & (x - 1)) == 0))
+
+io_type_t device_type_block(void);
+
+static int block_open(io_dev_info_t *dev_info, const uintptr_t spec,
+		      io_entity_t *entity);
+static int block_seek(io_entity_t *entity, int mode, ssize_t offset);
+static int block_read(io_entity_t *entity, uintptr_t buffer, size_t length,
+		      size_t *length_read);
+static int block_write(io_entity_t *entity, const uintptr_t buffer,
+		       size_t length, size_t *length_written);
+static int block_close(io_entity_t *entity);
+static int block_dev_open(const uintptr_t dev_spec, io_dev_info_t **dev_info);
+static int block_dev_close(io_dev_info_t *dev_info);
+
+static const io_dev_connector_t block_dev_connector = {
+	.dev_open	= block_dev_open
+};
+
+static const io_dev_funcs_t block_dev_funcs = {
+	.type		= device_type_block,
+	.open		= block_open,
+	.seek		= block_seek,
+	.size		= NULL,
+	.read		= block_read,
+	.write		= block_write,
+	.close		= block_close,
+	.dev_init	= NULL,
+	.dev_close	= block_dev_close,
+};
+
+static block_dev_state_t state_pool[MAX_IO_BLOCK_DEVICES];
+static io_dev_info_t dev_info_pool[MAX_IO_BLOCK_DEVICES];
+
+/* Track number of allocated block state */
+static unsigned int block_dev_count;
+
+io_type_t device_type_block(void)
+{
+	return IO_TYPE_BLOCK;
+}
+
+/* Locate a block state in the pool, specified by address */
+static int find_first_block_state(const io_block_dev_spec_t *dev_spec,
+				  unsigned int *index_out)
+{
+	int result = -ENOENT;
+	for (int index = 0; index < MAX_IO_BLOCK_DEVICES; ++index) {
+		/* dev_spec is used as identifier since it's unique */
+		if (state_pool[index].dev_spec == dev_spec) {
+			result = 0;
+			*index_out = index;
+			break;
+		}
+	}
+	return result;
+}
+
+/* Allocate a device info from the pool and return a pointer to it */
+static int allocate_dev_info(io_dev_info_t **dev_info)
+{
+	int result = -ENOMEM;
+	assert(dev_info != NULL);
+
+	if (block_dev_count < MAX_IO_BLOCK_DEVICES) {
+		unsigned int index = 0;
+		result = find_first_block_state(NULL, &index);
+		assert(result == 0);
+		/* initialize dev_info */
+		dev_info_pool[index].funcs = &block_dev_funcs;
+		dev_info_pool[index].info = (uintptr_t)&state_pool[index];
+		*dev_info = &dev_info_pool[index];
+		++block_dev_count;
+	}
+
+	return result;
+}
+
+
+/* Release a device info to the pool */
+static int free_dev_info(io_dev_info_t *dev_info)
+{
+	int result;
+	unsigned int index = 0;
+	block_dev_state_t *state;
+	assert(dev_info != NULL);
+
+	state = (block_dev_state_t *)dev_info->info;
+	result = find_first_block_state(state->dev_spec, &index);
+	if (result ==  0) {
+		/* free if device info is valid */
+		memset(state, 0, sizeof(block_dev_state_t));
+		memset(dev_info, 0, sizeof(io_dev_info_t));
+		--block_dev_count;
+	}
+
+	return result;
+}
+
+static int block_open(io_dev_info_t *dev_info, const uintptr_t spec,
+		      io_entity_t *entity)
+{
+	block_dev_state_t *cur;
+	io_block_spec_t *region;
+
+	assert((dev_info->info != (uintptr_t)NULL) &&
+	       (spec != (uintptr_t)NULL) &&
+	       (entity->info == (uintptr_t)NULL));
+
+	region = (io_block_spec_t *)spec;
+	cur = (block_dev_state_t *)dev_info->info;
+	assert(((region->offset % cur->dev_spec->block_size) == 0) &&
+	       ((region->length % cur->dev_spec->block_size) == 0));
+
+	cur->base = region->offset;
+	cur->size = region->length;
+	cur->file_pos = 0;
+
+	entity->info = (uintptr_t)cur;
+	return 0;
+}
+
+/* parameter offset is relative address at here */
+static int block_seek(io_entity_t *entity, int mode, ssize_t offset)
+{
+	block_dev_state_t *cur;
+
+	assert(entity->info != (uintptr_t)NULL);
+
+	cur = (block_dev_state_t *)entity->info;
+	assert((offset >= 0) && (offset < cur->size));
+
+	switch (mode) {
+	case IO_SEEK_SET:
+		cur->file_pos = offset;
+		break;
+	case IO_SEEK_CUR:
+		cur->file_pos += offset;
+		break;
+	default:
+		return -EINVAL;
+	}
+	assert(cur->file_pos < cur->size);
+	return 0;
+}
+
+static int block_read(io_entity_t *entity, uintptr_t buffer, size_t length,
+		      size_t *length_read)
+{
+	block_dev_state_t *cur;
+	io_block_spec_t *buf;
+	io_block_ops_t *ops;
+	size_t aligned_length, skip, count, left, padding, block_size;
+	int lba;
+
+	assert(entity->info != (uintptr_t)NULL);
+	cur = (block_dev_state_t *)entity->info;
+	ops = &(cur->dev_spec->ops);
+	buf = &(cur->dev_spec->buffer);
+	block_size = cur->dev_spec->block_size;
+	assert((length <= cur->size) &&
+	       (length > 0) &&
+	       (ops->read != 0));
+
+	skip = cur->file_pos % block_size;
+	aligned_length = ((skip + length) + (block_size - 1)) &
+			 ~(block_size - 1);
+	padding = aligned_length - (skip + length);
+	left = aligned_length;
+	do {
+		lba = (cur->file_pos + cur->base) / block_size;
+		if (left >= buf->length) {
+			/* Since left is larger, it's impossible to padding. */
+			if (skip) {
+				/*
+				 * The beginning address (file_pos) isn't
+				 * aligned with block size, we need to use
+				 * block buffer to read block. Since block
+				 * device is always relied on DMA operation.
+				 */
+				count = ops->read(lba, buf->offset,
+						  buf->length);
+			} else {
+				count = ops->read(lba, buffer, buf->length);
+			}
+			assert(count == buf->length);
+			cur->file_pos += count - skip;
+			if (skip) {
+				/*
+				 * Since it's not aligned with block size,
+				 * block buffer is used to store data.
+				 */
+				memcpy((void *)buffer,
+				       (void *)(buf->offset + skip),
+				       count - skip);
+			}
+			left = left - (count - skip);
+		} else {
+			if (skip || padding) {
+				/*
+				 * The beginning address (file_pos) isn't
+				 * aligned with block size, we have to read
+				 * full block by block buffer instead.
+				 * The size isn't aligned with block size.
+				 * Use block buffer to avoid overflow.
+				 */
+				count = ops->read(lba, buf->offset, left);
+			} else
+				count = ops->read(lba, buffer, left);
+			assert(count == left);
+			left = left - (skip + padding);
+			cur->file_pos += left;
+			if (skip || padding) {
+				/*
+				 * Since it's not aligned with block size,
+				 * block buffer is used to store data.
+				 */
+				memcpy((void *)buffer,
+				       (void *)(buf->offset + skip),
+				       left);
+			}
+			/* It's already the last block operation */
+			left = 0;
+		}
+		skip = cur->file_pos % block_size;
+	} while (left > 0);
+	*length_read = length;
+
+	return 0;
+}
+
+static int block_write(io_entity_t *entity, const uintptr_t buffer,
+		       size_t length, size_t *length_written)
+{
+	block_dev_state_t *cur;
+	io_block_spec_t *buf;
+	io_block_ops_t *ops;
+	size_t aligned_length, skip, count, left, padding, block_size;
+	int lba;
+
+	assert(entity->info != (uintptr_t)NULL);
+	cur = (block_dev_state_t *)entity->info;
+	ops = &(cur->dev_spec->ops);
+	buf = &(cur->dev_spec->buffer);
+	block_size = cur->dev_spec->block_size;
+	assert((length <= cur->size) &&
+	       (length > 0) &&
+	       (ops->read != 0) &&
+	       (ops->write != 0));
+
+	skip = cur->file_pos % block_size;
+	aligned_length = ((skip + length) + (block_size - 1)) &
+			 ~(block_size - 1);
+	padding = aligned_length - (skip + length);
+	left = aligned_length;
+	do {
+		lba = (cur->file_pos + cur->base) / block_size;
+		if (left >= buf->length) {
+			/* Since left is larger, it's impossible to padding. */
+			if (skip) {
+				/*
+				 * The beginning address (file_pos) isn't
+				 * aligned with block size, we need to use
+				 * block buffer to write block. Since block
+				 * device is always relied on DMA operation.
+				 */
+				count = ops->read(lba, buf->offset,
+						  buf->length);
+				assert(count == buf->length);
+				memcpy((void *)(buf->offset + skip),
+				       (void *)buffer,
+				       count - skip);
+				count = ops->write(lba, buf->offset,
+						   buf->length);
+			} else
+				count = ops->write(lba, buffer, buf->length);
+			assert(count == buf->length);
+			cur->file_pos += count - skip;
+			left = left - (count - skip);
+		} else {
+			if (skip || padding) {
+				/*
+				 * The beginning address (file_pos) isn't
+				 * aligned with block size, we need to avoid
+				 * poluate data in the beginning. Reading and
+				 * skipping the beginning is the only way.
+				 * The size isn't aligned with block size.
+				 * Use block buffer to avoid overflow.
+				 */
+				count = ops->read(lba, buf->offset, left);
+				assert(count == left);
+				memcpy((void *)(buf->offset + skip),
+				       (void *)buffer,
+				       left - skip - padding);
+				count = ops->write(lba, buf->offset, left);
+			} else
+				count = ops->write(lba, buffer, left);
+			assert(count == left);
+			cur->file_pos += left - (skip + padding);
+			/* It's already the last block operation */
+			left = 0;
+		}
+		skip = cur->file_pos % block_size;
+	} while (left > 0);
+	*length_written = length;
+	return 0;
+}
+
+static int block_close(io_entity_t *entity)
+{
+	entity->info = (uintptr_t)NULL;
+	return 0;
+}
+
+static int block_dev_open(const uintptr_t dev_spec, io_dev_info_t **dev_info)
+{
+	block_dev_state_t *cur;
+	io_block_spec_t *buffer;
+	io_dev_info_t *info;
+	size_t block_size;
+	int result;
+
+	assert(dev_info != NULL);
+	result = allocate_dev_info(&info);
+	if (result)
+		return -ENOENT;
+
+	cur = (block_dev_state_t *)info->info;
+	/* dev_spec is type of io_block_dev_spec_t. */
+	cur->dev_spec = (io_block_dev_spec_t *)dev_spec;
+	buffer = &(cur->dev_spec->buffer);
+	block_size = cur->dev_spec->block_size;
+	assert((block_size > 0) &&
+	       (is_power_of_2(block_size) != 0) &&
+	       ((buffer->offset % block_size) == 0) &&
+	       ((buffer->length % block_size) == 0));
+
+	*dev_info = info;	/* cast away const */
+	(void)block_size;
+	(void)buffer;
+	return 0;
+}
+
+static int block_dev_close(io_dev_info_t *dev_info)
+{
+	return free_dev_info(dev_info);
+}
+
+/* Exported functions */
+
+/* Register the Block driver with the IO abstraction */
+int register_io_dev_block(const io_dev_connector_t **dev_con)
+{
+	int result;
+
+	assert(dev_con != NULL);
+
+	/*
+	 * Since dev_info isn't really used in io_register_device, always
+	 * use the same device info at here instead.
+	 */
+	result = io_register_device(&dev_info_pool[0]);
+	if (result == 0)
+		*dev_con = &block_dev_connector;
+	return result;
+}