Adding upstream version 2.10.0+dfsg.upstream/2.10.0+dfsgupstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

7 files changed, 2346 insertions, 0 deletions

diff --git a/drivers/io/io_block.c b/drivers/io/io_block.c
new file mode 100644
index 0000000..b5e0e5f
--- /dev/null
+++ b/drivers/io/io_block.c
@@ -0,0 +1,551 @@
+/*
+ * Copyright (c) 2016-2023, ARM Limited and Contributors. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include <assert.h>
+#include <errno.h>
+#include <string.h>
+
+#include <platform_def.h>
+
+#include <common/debug.h>
+#include <drivers/io/io_block.h>
+#include <drivers/io/io_driver.h>
+#include <drivers/io/io_storage.h>
+#include <lib/utils.h>
+
+typedef struct {
+	io_block_dev_spec_t	*dev_spec;
+	uintptr_t		base;
+	unsigned long long	file_pos;
+	unsigned long long	size;
+} block_dev_state_t;
+
+#define is_power_of_2(x)	(((x) != 0U) && (((x) & ((x) - 1U)) == 0U))
+
+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, signed long long 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)
+{
+	unsigned int index;
+	int result = -ENOENT;
+
+	for (index = 0U; 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 */
+		zeromem(state, sizeof(block_dev_state_t));
+		zeromem(dev_info, 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, signed long long offset)
+{
+	block_dev_state_t *cur;
+
+	assert(entity->info != (uintptr_t)NULL);
+
+	cur = (block_dev_state_t *)entity->info;
+	assert((offset >= 0) && ((unsigned long long)offset < cur->size));
+
+	switch (mode) {
+	case IO_SEEK_SET:
+		cur->file_pos = (unsigned long long)offset;
+		break;
+	case IO_SEEK_CUR:
+		cur->file_pos += (unsigned long long)offset;
+		break;
+	default:
+		return -EINVAL;
+	}
+	assert(cur->file_pos < cur->size);
+	return 0;
+}
+
+/*
+ * This function allows the caller to read any number of bytes
+ * from any position. It hides from the caller that the low level
+ * driver only can read aligned blocks of data. For this reason
+ * we need to handle the use case where the first byte to be read is not
+ * aligned to start of the block, the last byte to be read is also not
+ * aligned to the end of a block, and there are zero or more blocks-worth
+ * of data in between.
+ *
+ * In such a case we need to read more bytes than requested (i.e. full
+ * blocks) and strip-out the leading bytes (aka skip) and the trailing
+ * bytes (aka padding). See diagram below
+ *
+ * cur->file_pos ------------
+ *                          |
+ * cur->base                |
+ *  |                       |
+ *  v                       v<----  length   ---->
+ *  --------------------------------------------------------------
+ * |           |         block#1    |        |   block#n          |
+ * |  block#0  |            +       |   ...  |     +              |
+ * |           | <- skip -> +       |        |     + <- padding ->|
+ *  ------------------------+----------------------+--------------
+ *             ^                                                  ^
+ *             |                                                  |
+ *             v    iteration#1                iteration#n        v
+ *              --------------------------------------------------
+ *             |                    |        |                    |
+ *             |<----  request ---->|  ...   |<----- request ---->|
+ *             |                    |        |                    |
+ *              --------------------------------------------------
+ *            /                   /          |                    |
+ *           /                   /           |                    |
+ *          /                   /            |                    |
+ *         /                   /             |                    |
+ *        /                   /              |                    |
+ *       /                   /               |                    |
+ *      /                   /                |                    |
+ *     /                   /                 |                    |
+ *    /                   /                  |                    |
+ *   /                   /                   |                    |
+ *  <---- request ------>                    <------ request  ----->
+ *  ---------------------                    -----------------------
+ *  |        |          |                    |          |           |
+ *  |<-skip->|<-nbytes->|           -------->|<-nbytes->|<-padding->|
+ *  |        |          |           |        |          |           |
+ *  ---------------------           |        -----------------------
+ *  ^        \           \          |        |          |
+ *  |         \           \         |        |          |
+ *  |          \           \        |        |          |
+ *  buf->offset \           \   buf->offset  |          |
+ *               \           \               |          |
+ *                \           \              |          |
+ *                 \           \             |          |
+ *                  \           \            |          |
+ *                   \           \           |          |
+ *                    \           \          |          |
+ *                     \           \         |          |
+ *                      --------------------------------
+ *                      |           |        |         |
+ * buffer-------------->|           | ...    |         |
+ *                      |           |        |         |
+ *                      --------------------------------
+ *                      <-count#1->|                   |
+ *                      <----------  count#n   -------->
+ *                      <----------  length  ---------->
+ *
+ * Additionally, the IO driver has an underlying buffer that is at least
+ * one block-size and may be big enough to allow.
+ */
+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;
+	int lba;
+	size_t block_size, left;
+	size_t nbytes;  /* number of bytes read in one iteration */
+	size_t request; /* number of requested bytes in one iteration */
+	size_t count;   /* number of bytes already read */
+	/*
+	 * number of leading bytes from start of the block
+	 * to the first byte to be read
+	 */
+	size_t skip;
+
+	/*
+	 * number of trailing bytes between the last byte
+	 * to be read and the end of the block
+	 */
+	size_t padding;
+
+	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 > 0U) &&
+	       (ops->read != NULL));
+
+	/*
+	 * We don't know the number of bytes that we are going
+	 * to read in every iteration, because it will depend
+	 * on the low level driver.
+	 */
+	count = 0;
+	for (left = length; left > 0U; left -= nbytes) {
+		/*
+		 * We must only request operations aligned to the block
+		 * size. Therefore if file_pos is not block-aligned,
+		 * we have to request the operation to start at the
+		 * previous block boundary and skip the leading bytes. And
+		 * similarly, the number of bytes requested must be a
+		 * block size multiple
+		 */
+		skip = cur->file_pos & (block_size - 1U);
+
+		/*
+		 * Calculate the block number containing file_pos
+		 * - e.g. block 3.
+		 */
+		lba = (cur->file_pos + cur->base) / block_size;
+
+		if ((skip + left) > buf->length) {
+			/*
+			 * The underlying read buffer is too small to
+			 * read all the required data - limit to just
+			 * fill the buffer, and then read again.
+			 */
+			request = buf->length;
+		} else {
+			/*
+			 * The underlying read buffer is big enough to
+			 * read all the required data. Calculate the
+			 * number of bytes to read to align with the
+			 * block size.
+			 */
+			request = skip + left;
+			request = (request + (block_size - 1U)) &
+				~(block_size - 1U);
+		}
+		request = ops->read(lba, buf->offset, request);
+
+		if (request <= skip) {
+			/*
+			 * We couldn't read enough bytes to jump over
+			 * the skip bytes, so we should have to read
+			 * again the same block, thus generating
+			 * the same error.
+			 */
+			return -EIO;
+		}
+
+		/*
+		 * Need to remove skip and padding bytes,if any, from
+		 * the read data when copying to the user buffer.
+		 */
+		nbytes = request - skip;
+		padding = (nbytes > left) ? nbytes - left : 0U;
+		nbytes -= padding;
+
+		memcpy((void *)(buffer + count),
+		       (void *)(buf->offset + skip),
+		       nbytes);
+
+		cur->file_pos += nbytes;
+		count += nbytes;
+	}
+	assert(count == length);
+	*length_read = count;
+
+	return 0;
+}
+
+/*
+ * This function allows the caller to write any number of bytes
+ * from any position. It hides from the caller that the low level
+ * driver only can write aligned blocks of data.
+ * See comments for block_read for more details.
+ */
+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;
+	int lba;
+	size_t block_size, left;
+	size_t nbytes;  /* number of bytes read in one iteration */
+	size_t request; /* number of requested bytes in one iteration */
+	size_t count;   /* number of bytes already read */
+	/*
+	 * number of leading bytes from start of the block
+	 * to the first byte to be read
+	 */
+	size_t skip;
+
+	/*
+	 * number of trailing bytes between the last byte
+	 * to be read and the end of the block
+	 */
+	size_t padding;
+
+	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 > 0U) &&
+	       (ops->read != NULL) &&
+	       (ops->write != NULL));
+
+	/*
+	 * We don't know the number of bytes that we are going
+	 * to write in every iteration, because it will depend
+	 * on the low level driver.
+	 */
+	count = 0;
+	for (left = length; left > 0U; left -= nbytes) {
+		/*
+		 * We must only request operations aligned to the block
+		 * size. Therefore if file_pos is not block-aligned,
+		 * we have to request the operation to start at the
+		 * previous block boundary and skip the leading bytes. And
+		 * similarly, the number of bytes requested must be a
+		 * block size multiple
+		 */
+		skip = cur->file_pos & (block_size - 1U);
+
+		/*
+		 * Calculate the block number containing file_pos
+		 * - e.g. block 3.
+		 */
+		lba = (cur->file_pos + cur->base) / block_size;
+
+		if ((skip + left) > buf->length) {
+			/*
+			 * The underlying read buffer is too small to
+			 * read all the required data - limit to just
+			 * fill the buffer, and then read again.
+			 */
+			request = buf->length;
+		} else {
+			/*
+			 * The underlying read buffer is big enough to
+			 * read all the required data. Calculate the
+			 * number of bytes to read to align with the
+			 * block size.
+			 */
+			request = skip + left;
+			request = (request + (block_size - 1U)) &
+				~(block_size - 1U);
+		}
+
+		/*
+		 * The number of bytes that we are going to write
+		 * from the user buffer will depend of the size
+		 * of the current request.
+		 */
+		nbytes = request - skip;
+		padding = (nbytes > left) ? nbytes - left : 0U;
+		nbytes -= padding;
+
+		/*
+		 * If we have skip or padding bytes then we have to preserve
+		 * some content and it means that we have to read before
+		 * writing
+		 */
+		if ((skip > 0U) || (padding > 0U)) {
+			request = ops->read(lba, buf->offset, request);
+			/*
+			 * The read may return size less than
+			 * requested. Round down to the nearest block
+			 * boundary
+			 */
+			request &= ~(block_size - 1U);
+			if (request <= skip) {
+				/*
+				 * We couldn't read enough bytes to jump over
+				 * the skip bytes, so we should have to read
+				 * again the same block, thus generating
+				 * the same error.
+				 */
+				return -EIO;
+			}
+			nbytes = request - skip;
+			padding = (nbytes > left) ? nbytes - left : 0U;
+			nbytes -= padding;
+		}
+
+		memcpy((void *)(buf->offset + skip),
+		       (void *)(buffer + count),
+		       nbytes);
+
+		request = ops->write(lba, buf->offset, request);
+		if (request <= skip)
+			return -EIO;
+
+		/*
+		 * And the previous write operation may modify the size
+		 * of the request, so again, we have to calculate the
+		 * number of bytes that we consumed from the user
+		 * buffer
+		 */
+		nbytes = request - skip;
+		padding = (nbytes > left) ? nbytes - left : 0U;
+		nbytes -= padding;
+
+		cur->file_pos += nbytes;
+		count += nbytes;
+	}
+	assert(count == length);
+	*length_written = count;
+
+	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 != 0)
+		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 > 0U) &&
+	       (is_power_of_2(block_size) != 0U) &&
+	       ((buffer->offset % block_size) == 0U) &&
+	       ((buffer->length % block_size) == 0U));
+
+	*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;
+}
diff --git a/drivers/io/io_encrypted.c b/drivers/io/io_encrypted.c
new file mode 100644
index 0000000..744ca83
--- /dev/null
+++ b/drivers/io/io_encrypted.c
@@ -0,0 +1,244 @@
+/*
+ * Copyright (c) 2020, Linaro Limited. All rights reserved.
+ * Author: Sumit Garg <sumit.garg@linaro.org>
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include <assert.h>
+#include <errno.h>
+#include <stdint.h>
+#include <string.h>
+
+#include <platform_def.h>
+
+#include <common/bl_common.h>
+#include <common/debug.h>
+#include <drivers/auth/crypto_mod.h>
+#include <drivers/io/io_driver.h>
+#include <drivers/io/io_encrypted.h>
+#include <drivers/io/io_storage.h>
+#include <lib/utils.h>
+#include <plat/common/platform.h>
+#include <tools_share/firmware_encrypted.h>
+#include <tools_share/uuid.h>
+
+static uintptr_t backend_dev_handle;
+static uintptr_t backend_dev_spec;
+static uintptr_t backend_handle;
+static uintptr_t backend_image_spec;
+
+static io_dev_info_t enc_dev_info;
+
+/* Encrypted firmware driver functions */
+static int enc_dev_open(const uintptr_t dev_spec, io_dev_info_t **dev_info);
+static int enc_file_open(io_dev_info_t *dev_info, const uintptr_t spec,
+			  io_entity_t *entity);
+static int enc_file_len(io_entity_t *entity, size_t *length);
+static int enc_file_read(io_entity_t *entity, uintptr_t buffer, size_t length,
+			  size_t *length_read);
+static int enc_file_close(io_entity_t *entity);
+static int enc_dev_init(io_dev_info_t *dev_info, const uintptr_t init_params);
+static int enc_dev_close(io_dev_info_t *dev_info);
+
+static inline int is_valid_header(struct fw_enc_hdr *header)
+{
+	if (header->magic == ENC_HEADER_MAGIC)
+		return 1;
+	else
+		return 0;
+}
+
+static io_type_t device_type_enc(void)
+{
+	return IO_TYPE_ENCRYPTED;
+}
+
+static const io_dev_connector_t enc_dev_connector = {
+	.dev_open = enc_dev_open
+};
+
+static const io_dev_funcs_t enc_dev_funcs = {
+	.type = device_type_enc,
+	.open = enc_file_open,
+	.seek = NULL,
+	.size = enc_file_len,
+	.read = enc_file_read,
+	.write = NULL,
+	.close = enc_file_close,
+	.dev_init = enc_dev_init,
+	.dev_close = enc_dev_close,
+};
+
+static int enc_dev_open(const uintptr_t dev_spec, io_dev_info_t **dev_info)
+{
+	assert(dev_info != NULL);
+
+	enc_dev_info.funcs = &enc_dev_funcs;
+	*dev_info = &enc_dev_info;
+
+	return 0;
+}
+
+static int enc_dev_init(io_dev_info_t *dev_info, const uintptr_t init_params)
+{
+	int result;
+	unsigned int image_id = (unsigned int)init_params;
+
+	/* Obtain a reference to the image by querying the platform layer */
+	result = plat_get_image_source(image_id, &backend_dev_handle,
+				       &backend_dev_spec);
+	if (result != 0) {
+		WARN("Failed to obtain reference to image id=%u (%i)\n",
+			image_id, result);
+		return -ENOENT;
+	}
+
+	return result;
+}
+
+static int enc_dev_close(io_dev_info_t *dev_info)
+{
+	backend_dev_handle = (uintptr_t)NULL;
+	backend_dev_spec = (uintptr_t)NULL;
+
+	return 0;
+}
+
+static int enc_file_open(io_dev_info_t *dev_info, const uintptr_t spec,
+			 io_entity_t *entity)
+{
+	int result;
+
+	assert(spec != 0);
+	assert(entity != NULL);
+
+	backend_image_spec = spec;
+
+	result = io_open(backend_dev_handle, backend_image_spec,
+			 &backend_handle);
+	if (result != 0) {
+		WARN("Failed to open backend device (%i)\n", result);
+		result = -ENOENT;
+	}
+
+	return result;
+}
+
+static int enc_file_len(io_entity_t *entity, size_t *length)
+{
+	int result;
+
+	assert(entity != NULL);
+	assert(length != NULL);
+
+	result = io_size(backend_handle, length);
+	if (result != 0) {
+		WARN("Failed to read blob length (%i)\n", result);
+		return -ENOENT;
+	}
+
+	/*
+	 * Encryption header is attached at the beginning of the encrypted file
+	 * and is not considered a part of the payload.
+	 */
+	if (*length < sizeof(struct fw_enc_hdr))
+		return -EIO;
+
+	*length -= sizeof(struct fw_enc_hdr);
+
+	return result;
+}
+
+static int enc_file_read(io_entity_t *entity, uintptr_t buffer, size_t length,
+			 size_t *length_read)
+{
+	int result;
+	struct fw_enc_hdr header;
+	enum fw_enc_status_t fw_enc_status;
+	size_t bytes_read;
+	uint8_t key[ENC_MAX_KEY_SIZE];
+	size_t key_len = sizeof(key);
+	unsigned int key_flags = 0;
+	const io_uuid_spec_t *uuid_spec = (io_uuid_spec_t *)backend_image_spec;
+
+	assert(entity != NULL);
+	assert(length_read != NULL);
+
+	result = io_read(backend_handle, (uintptr_t)&header, sizeof(header),
+			 &bytes_read);
+	if (result != 0) {
+		WARN("Failed to read encryption header (%i)\n", result);
+		return -ENOENT;
+	}
+
+	if (!is_valid_header(&header)) {
+		WARN("Encryption header check failed.\n");
+		return -ENOENT;
+	}
+
+	VERBOSE("Encryption header looks OK.\n");
+	fw_enc_status = header.flags & FW_ENC_STATUS_FLAG_MASK;
+
+	if ((header.iv_len > ENC_MAX_IV_SIZE) ||
+	    (header.tag_len > ENC_MAX_TAG_SIZE)) {
+		WARN("Incorrect IV or tag length\n");
+		return -ENOENT;
+	}
+
+	result = io_read(backend_handle, buffer, length, &bytes_read);
+	if (result != 0) {
+		WARN("Failed to read encrypted payload (%i)\n", result);
+		return -ENOENT;
+	}
+
+	*length_read = bytes_read;
+
+	result = plat_get_enc_key_info(fw_enc_status, key, &key_len, &key_flags,
+				       (uint8_t *)&uuid_spec->uuid,
+				       sizeof(uuid_t));
+	if (result != 0) {
+		WARN("Failed to obtain encryption key (%i)\n", result);
+		return -ENOENT;
+	}
+
+	result = crypto_mod_auth_decrypt(header.dec_algo,
+					 (void *)buffer, *length_read, key,
+					 key_len, key_flags, header.iv,
+					 header.iv_len, header.tag,
+					 header.tag_len);
+	memset(key, 0, key_len);
+
+	if (result != 0) {
+		ERROR("File decryption failed (%i)\n", result);
+		return -ENOENT;
+	}
+
+	return result;
+}
+
+static int enc_file_close(io_entity_t *entity)
+{
+	io_close(backend_handle);
+
+	backend_image_spec = (uintptr_t)NULL;
+	entity->info = 0;
+
+	return 0;
+}
+
+/* Exported functions */
+
+/* Register the Encrypted Firmware driver with the IO abstraction */
+int register_io_dev_enc(const io_dev_connector_t **dev_con)
+{
+	int result;
+
+	assert(dev_con != NULL);
+
+	result = io_register_device(&enc_dev_info);
+	if (result == 0)
+		*dev_con = &enc_dev_connector;
+
+	return result;
+}
diff --git a/drivers/io/io_fip.c b/drivers/io/io_fip.c
new file mode 100644
index 0000000..6e15295
--- /dev/null
+++ b/drivers/io/io_fip.c
@@ -0,0 +1,481 @@
+/*
+ * Copyright (c) 2014-2020, ARM Limited and Contributors. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include <assert.h>
+#include <errno.h>
+#include <stdint.h>
+#include <string.h>
+
+#include <platform_def.h>
+
+#include <common/bl_common.h>
+#include <common/debug.h>
+#include <drivers/io/io_driver.h>
+#include <drivers/io/io_fip.h>
+#include <drivers/io/io_storage.h>
+#include <lib/utils.h>
+#include <plat/common/platform.h>
+#include <tools_share/firmware_image_package.h>
+#include <tools_share/uuid.h>
+
+#ifndef MAX_FIP_DEVICES
+#define MAX_FIP_DEVICES		1
+#endif
+
+/* Useful for printing UUIDs when debugging.*/
+#define PRINT_UUID2(x)								\
+	"%08x-%04hx-%04hx-%02hhx%02hhx-%02hhx%02hhx%02hhx%02hhx%02hhx%02hhx",	\
+		x.time_low, x.time_mid, x.time_hi_and_version,			\
+		x.clock_seq_hi_and_reserved, x.clock_seq_low,			\
+		x.node[0], x.node[1], x.node[2], x.node[3],			\
+		x.node[4], x.node[5]
+
+typedef struct {
+	unsigned int file_pos;
+	fip_toc_entry_t entry;
+} fip_file_state_t;
+
+/*
+ * Maintain dev_spec per FIP Device
+ * TODO - Add backend handles and file state
+ * per FIP device here once backends like io_memmap
+ * can support multiple open files
+ */
+typedef struct {
+	uintptr_t dev_spec;
+	uint16_t plat_toc_flag;
+} fip_dev_state_t;
+
+/*
+ * Only one file can be open across all FIP device
+ * as backends like io_memmap don't support
+ * multiple open files. The file state and
+ * backend handle should be maintained per FIP device
+ * if the same support is available in the backend
+ */
+static fip_file_state_t current_fip_file = {0};
+static uintptr_t backend_dev_handle;
+static uintptr_t backend_image_spec;
+
+static fip_dev_state_t state_pool[MAX_FIP_DEVICES];
+static io_dev_info_t dev_info_pool[MAX_FIP_DEVICES];
+
+/* Track number of allocated fip devices */
+static unsigned int fip_dev_count;
+
+/* Firmware Image Package driver functions */
+static int fip_dev_open(const uintptr_t dev_spec, io_dev_info_t **dev_info);
+static int fip_file_open(io_dev_info_t *dev_info, const uintptr_t spec,
+			  io_entity_t *entity);
+static int fip_file_len(io_entity_t *entity, size_t *length);
+static int fip_file_read(io_entity_t *entity, uintptr_t buffer, size_t length,
+			  size_t *length_read);
+static int fip_file_close(io_entity_t *entity);
+static int fip_dev_init(io_dev_info_t *dev_info, const uintptr_t init_params);
+static int fip_dev_close(io_dev_info_t *dev_info);
+
+
+/* Return 0 for equal uuids. */
+static inline int compare_uuids(const uuid_t *uuid1, const uuid_t *uuid2)
+{
+	return memcmp(uuid1, uuid2, sizeof(uuid_t));
+}
+
+
+static inline int is_valid_header(fip_toc_header_t *header)
+{
+	if ((header->name == TOC_HEADER_NAME) && (header->serial_number != 0)) {
+		return 1;
+	} else {
+		return 0;
+	}
+}
+
+
+/* Identify the device type as a virtual driver */
+static io_type_t device_type_fip(void)
+{
+	return IO_TYPE_FIRMWARE_IMAGE_PACKAGE;
+}
+
+
+static const io_dev_connector_t fip_dev_connector = {
+	.dev_open = fip_dev_open
+};
+
+
+static const io_dev_funcs_t fip_dev_funcs = {
+	.type = device_type_fip,
+	.open = fip_file_open,
+	.seek = NULL,
+	.size = fip_file_len,
+	.read = fip_file_read,
+	.write = NULL,
+	.close = fip_file_close,
+	.dev_init = fip_dev_init,
+	.dev_close = fip_dev_close,
+};
+
+/* Locate a file state in the pool, specified by address */
+static int find_first_fip_state(const uintptr_t dev_spec,
+				  unsigned int *index_out)
+{
+	int result = -ENOENT;
+	unsigned int index;
+
+	for (index = 0; index < (unsigned int)MAX_FIP_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 (fip_dev_count < (unsigned int)MAX_FIP_DEVICES) {
+		unsigned int index = 0;
+
+		result = find_first_fip_state(0, &index);
+		assert(result == 0);
+		/* initialize dev_info */
+		dev_info_pool[index].funcs = &fip_dev_funcs;
+		dev_info_pool[index].info =
+				(uintptr_t)&state_pool[index];
+		*dev_info = &dev_info_pool[index];
+		++fip_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;
+	fip_dev_state_t *state;
+
+	assert(dev_info != NULL);
+
+	state = (fip_dev_state_t *)dev_info->info;
+	result = find_first_fip_state(state->dev_spec, &index);
+	if (result ==  0) {
+		/* free if device info is valid */
+		zeromem(state, sizeof(fip_dev_state_t));
+		--fip_dev_count;
+	}
+
+	return result;
+}
+
+/*
+ * Multiple FIP devices can be opened depending on the value of
+ * MAX_FIP_DEVICES. Given that there is only one backend, only a
+ * single file can be open at a time by any FIP device.
+ */
+static int fip_dev_open(const uintptr_t dev_spec,
+			 io_dev_info_t **dev_info)
+{
+	int result;
+	io_dev_info_t *info;
+	fip_dev_state_t *state;
+
+	assert(dev_info != NULL);
+#if MAX_FIP_DEVICES > 1
+	assert(dev_spec != (uintptr_t)NULL);
+#endif
+
+	result = allocate_dev_info(&info);
+	if (result != 0)
+		return -ENOMEM;
+
+	state = (fip_dev_state_t *)info->info;
+
+	state->dev_spec = dev_spec;
+
+	*dev_info = info;
+
+	return 0;
+}
+
+
+/* Do some basic package checks. */
+static int fip_dev_init(io_dev_info_t *dev_info, const uintptr_t init_params)
+{
+	int result;
+	unsigned int image_id = (unsigned int)init_params;
+	uintptr_t backend_handle;
+	fip_toc_header_t header;
+	size_t bytes_read;
+	fip_dev_state_t *state;
+
+	assert(dev_info != NULL);
+
+	state = (fip_dev_state_t *)dev_info->info;
+
+	/* Obtain a reference to the image by querying the platform layer */
+	result = plat_get_image_source(image_id, &backend_dev_handle,
+				       &backend_image_spec);
+	if (result != 0) {
+		WARN("Failed to obtain reference to image id=%u (%i)\n",
+			image_id, result);
+		result = -ENOENT;
+		goto fip_dev_init_exit;
+	}
+
+	/* Attempt to access the FIP image */
+	result = io_open(backend_dev_handle, backend_image_spec,
+			 &backend_handle);
+	if (result != 0) {
+		WARN("Failed to access image id=%u (%i)\n", image_id, result);
+		result = -ENOENT;
+		goto fip_dev_init_exit;
+	}
+
+	result = io_read(backend_handle, (uintptr_t)&header, sizeof(header),
+			&bytes_read);
+	if (result == 0) {
+		if (!is_valid_header(&header)) {
+			WARN("Firmware Image Package header check failed.\n");
+			result = -ENOENT;
+		} else {
+			VERBOSE("FIP header looks OK.\n");
+			/*
+			 * Store 16-bit Platform ToC flags field which occupies
+			 * bits [32-47] in fip header.
+			 */
+			state->plat_toc_flag = (header.flags >> 32) & 0xffff;
+		}
+	}
+
+	io_close(backend_handle);
+
+ fip_dev_init_exit:
+	return result;
+}
+
+/* Close a connection to the FIP device */
+static int fip_dev_close(io_dev_info_t *dev_info)
+{
+	/* TODO: Consider tracking open files and cleaning them up here */
+
+	/* Clear the backend. */
+	backend_dev_handle = (uintptr_t)NULL;
+	backend_image_spec = (uintptr_t)NULL;
+
+	return free_dev_info(dev_info);
+}
+
+
+/* Open a file for access from package. */
+static int fip_file_open(io_dev_info_t *dev_info, const uintptr_t spec,
+			 io_entity_t *entity)
+{
+	int result;
+	uintptr_t backend_handle;
+	const io_uuid_spec_t *uuid_spec = (io_uuid_spec_t *)spec;
+	static const uuid_t uuid_null = { {0} }; /* Double braces for clang */
+	size_t bytes_read;
+	int found_file = 0;
+
+	assert(uuid_spec != NULL);
+	assert(entity != NULL);
+
+	/* Can only have one file open at a time for the moment. We need to
+	 * track state like file cursor position. We know the header lives at
+	 * offset zero, so this entry should never be zero for an active file.
+	 * When the system supports dynamic memory allocation we can allow more
+	 * than one open file at a time if needed.
+	 */
+	if (current_fip_file.entry.offset_address != 0U) {
+		WARN("fip_file_open : Only one open file at a time.\n");
+		return -ENFILE;
+	}
+
+	/* Attempt to access the FIP image */
+	result = io_open(backend_dev_handle, backend_image_spec,
+			 &backend_handle);
+	if (result != 0) {
+		WARN("Failed to open Firmware Image Package (%i)\n", result);
+		result = -ENOENT;
+		goto fip_file_open_exit;
+	}
+
+	/* Seek past the FIP header into the Table of Contents */
+	result = io_seek(backend_handle, IO_SEEK_SET,
+			 (signed long long)sizeof(fip_toc_header_t));
+	if (result != 0) {
+		WARN("fip_file_open: failed to seek\n");
+		result = -ENOENT;
+		goto fip_file_open_close;
+	}
+
+	found_file = 0;
+	do {
+		result = io_read(backend_handle,
+				 (uintptr_t)&current_fip_file.entry,
+				 sizeof(current_fip_file.entry),
+				 &bytes_read);
+		if (result == 0) {
+			if (compare_uuids(&current_fip_file.entry.uuid,
+					  &uuid_spec->uuid) == 0) {
+				found_file = 1;
+			}
+		} else {
+			WARN("Failed to read FIP (%i)\n", result);
+			goto fip_file_open_close;
+		}
+	} while ((found_file == 0) &&
+			(compare_uuids(&current_fip_file.entry.uuid,
+				&uuid_null) != 0));
+
+	if (found_file == 1) {
+		/* All fine. Update entity info with file state and return. Set
+		 * the file position to 0. The 'current_fip_file.entry' holds
+		 * the base and size of the file.
+		 */
+		current_fip_file.file_pos = 0;
+		entity->info = (uintptr_t)&current_fip_file;
+	} else {
+		/* Did not find the file in the FIP. */
+		current_fip_file.entry.offset_address = 0;
+		result = -ENOENT;
+	}
+
+ fip_file_open_close:
+	io_close(backend_handle);
+
+ fip_file_open_exit:
+	return result;
+}
+
+
+/* Return the size of a file in package */
+static int fip_file_len(io_entity_t *entity, size_t *length)
+{
+	assert(entity != NULL);
+	assert(length != NULL);
+
+	*length =  ((fip_file_state_t *)entity->info)->entry.size;
+
+	return 0;
+}
+
+
+/* Read data from a file in package */
+static int fip_file_read(io_entity_t *entity, uintptr_t buffer, size_t length,
+			  size_t *length_read)
+{
+	int result;
+	fip_file_state_t *fp;
+	size_t file_offset;
+	size_t bytes_read;
+	uintptr_t backend_handle;
+
+	assert(entity != NULL);
+	assert(length_read != NULL);
+	assert(entity->info != (uintptr_t)NULL);
+
+	/* Open the backend, attempt to access the blob image */
+	result = io_open(backend_dev_handle, backend_image_spec,
+			 &backend_handle);
+	if (result != 0) {
+		WARN("Failed to open FIP (%i)\n", result);
+		result = -ENOENT;
+		goto fip_file_read_exit;
+	}
+
+	fp = (fip_file_state_t *)entity->info;
+
+	/* Seek to the position in the FIP where the payload lives */
+	file_offset = fp->entry.offset_address + fp->file_pos;
+	result = io_seek(backend_handle, IO_SEEK_SET,
+			 (signed long long)file_offset);
+	if (result != 0) {
+		WARN("fip_file_read: failed to seek\n");
+		result = -ENOENT;
+		goto fip_file_read_close;
+	}
+
+	result = io_read(backend_handle, buffer, length, &bytes_read);
+	if (result != 0) {
+		/* We cannot read our data. Fail. */
+		WARN("Failed to read payload (%i)\n", result);
+		result = -ENOENT;
+		goto fip_file_read_close;
+	} else {
+		/* Set caller length and new file position. */
+		*length_read = bytes_read;
+		fp->file_pos += bytes_read;
+	}
+
+/* Close the backend. */
+ fip_file_read_close:
+	io_close(backend_handle);
+
+ fip_file_read_exit:
+	return result;
+}
+
+
+/* Close a file in package */
+static int fip_file_close(io_entity_t *entity)
+{
+	/* Clear our current file pointer.
+	 * If we had malloc() we would free() here.
+	 */
+	if (current_fip_file.entry.offset_address != 0U) {
+		zeromem(&current_fip_file, sizeof(current_fip_file));
+	}
+
+	/* Clear the Entity info. */
+	entity->info = 0;
+
+	return 0;
+}
+
+/* Exported functions */
+
+/* Register the Firmware Image Package driver with the IO abstraction */
+int register_io_dev_fip(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 = &fip_dev_connector;
+
+	return result;
+}
+
+/* Function to retrieve plat_toc_flags, previously saved in FIP dev */
+int fip_dev_get_plat_toc_flag(io_dev_info_t *dev_info, uint16_t *plat_toc_flag)
+{
+	fip_dev_state_t *state;
+
+	assert(dev_info != NULL);
+
+	state = (fip_dev_state_t *)dev_info->info;
+
+	*plat_toc_flag =  state->plat_toc_flag;
+
+	return 0;
+}
diff --git a/drivers/io/io_memmap.c b/drivers/io/io_memmap.c
new file mode 100644
index 0000000..eb69163
--- /dev/null
+++ b/drivers/io/io_memmap.c
@@ -0,0 +1,251 @@
+/*
+ * Copyright (c) 2014-2020, ARM Limited and Contributors. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include <assert.h>
+#include <string.h>
+
+#include <platform_def.h>
+
+#include <common/debug.h>
+#include <drivers/io/io_driver.h>
+#include <drivers/io/io_memmap.h>
+#include <drivers/io/io_storage.h>
+#include <lib/utils.h>
+
+/* As we need to be able to keep state for seek, only one file can be open
+ * at a time. Make this a structure and point to the entity->info. When we
+ * can malloc memory we can change this to support more open files.
+ */
+typedef struct {
+	/* Use the 'in_use' flag as any value for base and file_pos could be
+	 * valid.
+	 */
+	int			in_use;
+	uintptr_t		base;
+	unsigned long long	file_pos;
+	unsigned long long	size;
+} memmap_file_state_t;
+
+static memmap_file_state_t current_memmap_file = {0};
+
+/* Identify the device type as memmap */
+static io_type_t device_type_memmap(void)
+{
+	return IO_TYPE_MEMMAP;
+}
+
+/* Memmap device functions */
+static int memmap_dev_open(const uintptr_t dev_spec, io_dev_info_t **dev_info);
+static int memmap_block_open(io_dev_info_t *dev_info, const uintptr_t spec,
+			     io_entity_t *entity);
+static int memmap_block_seek(io_entity_t *entity, int mode,
+			     signed long long offset);
+static int memmap_block_len(io_entity_t *entity, size_t *length);
+static int memmap_block_read(io_entity_t *entity, uintptr_t buffer,
+			     size_t length, size_t *length_read);
+static int memmap_block_write(io_entity_t *entity, const uintptr_t buffer,
+			      size_t length, size_t *length_written);
+static int memmap_block_close(io_entity_t *entity);
+static int memmap_dev_close(io_dev_info_t *dev_info);
+
+
+static const io_dev_connector_t memmap_dev_connector = {
+	.dev_open = memmap_dev_open
+};
+
+
+static const io_dev_funcs_t memmap_dev_funcs = {
+	.type = device_type_memmap,
+	.open = memmap_block_open,
+	.seek = memmap_block_seek,
+	.size = memmap_block_len,
+	.read = memmap_block_read,
+	.write = memmap_block_write,
+	.close = memmap_block_close,
+	.dev_init = NULL,
+	.dev_close = memmap_dev_close,
+};
+
+
+/* No state associated with this device so structure can be const */
+static io_dev_info_t memmap_dev_info = {
+	.funcs = &memmap_dev_funcs,
+	.info = (uintptr_t)NULL
+};
+
+
+/* Open a connection to the memmap device */
+static int memmap_dev_open(const uintptr_t dev_spec __unused,
+			   io_dev_info_t **dev_info)
+{
+	assert(dev_info != NULL);
+	*dev_info = &memmap_dev_info;
+	return 0;
+}
+
+
+
+/* Close a connection to the memmap device */
+static int memmap_dev_close(io_dev_info_t *dev_info)
+{
+	/* NOP */
+	/* TODO: Consider tracking open files and cleaning them up here */
+	return 0;
+}
+
+
+/* Open a file on the memmap device */
+static int memmap_block_open(io_dev_info_t *dev_info, const uintptr_t spec,
+			     io_entity_t *entity)
+{
+	int result = -ENOMEM;
+	const io_block_spec_t *block_spec = (io_block_spec_t *)spec;
+
+	/* Since we need to track open state for seek() we only allow one open
+	 * spec at a time. When we have dynamic memory we can malloc and set
+	 * entity->info.
+	 */
+	if (current_memmap_file.in_use == 0) {
+		assert(block_spec != NULL);
+		assert(entity != NULL);
+
+		current_memmap_file.in_use = 1;
+		current_memmap_file.base = block_spec->offset;
+		/* File cursor offset for seek and incremental reads etc. */
+		current_memmap_file.file_pos = 0;
+		current_memmap_file.size = block_spec->length;
+		entity->info = (uintptr_t)&current_memmap_file;
+		result = 0;
+	} else {
+		WARN("A Memmap device is already active. Close first.\n");
+	}
+
+	return result;
+}
+
+
+/* Seek to a particular file offset on the memmap device */
+static int memmap_block_seek(io_entity_t *entity, int mode,
+			     signed long long offset)
+{
+	int result = -ENOENT;
+	memmap_file_state_t *fp;
+
+	/* We only support IO_SEEK_SET for the moment. */
+	if (mode == IO_SEEK_SET) {
+		assert(entity != NULL);
+
+		fp = (memmap_file_state_t *) entity->info;
+
+		/* Assert that new file position is valid */
+		assert((offset >= 0) &&
+		       ((unsigned long long)offset < fp->size));
+
+		/* Reset file position */
+		fp->file_pos = (unsigned long long)offset;
+		result = 0;
+	}
+
+	return result;
+}
+
+
+/* Return the size of a file on the memmap device */
+static int memmap_block_len(io_entity_t *entity, size_t *length)
+{
+	assert(entity != NULL);
+	assert(length != NULL);
+
+	*length = (size_t)((memmap_file_state_t *)entity->info)->size;
+
+	return 0;
+}
+
+
+/* Read data from a file on the memmap device */
+static int memmap_block_read(io_entity_t *entity, uintptr_t buffer,
+			     size_t length, size_t *length_read)
+{
+	memmap_file_state_t *fp;
+	unsigned long long pos_after;
+
+	assert(entity != NULL);
+	assert(length_read != NULL);
+
+	fp = (memmap_file_state_t *) entity->info;
+
+	/* Assert that file position is valid for this read operation */
+	pos_after = fp->file_pos + length;
+	assert((pos_after >= fp->file_pos) && (pos_after <= fp->size));
+
+	memcpy((void *)buffer,
+	       (void *)((uintptr_t)(fp->base + fp->file_pos)), length);
+
+	*length_read = length;
+
+	/* Set file position after read */
+	fp->file_pos = pos_after;
+
+	return 0;
+}
+
+
+/* Write data to a file on the memmap device */
+static int memmap_block_write(io_entity_t *entity, const uintptr_t buffer,
+			      size_t length, size_t *length_written)
+{
+	memmap_file_state_t *fp;
+	unsigned long long pos_after;
+
+	assert(entity != NULL);
+	assert(length_written != NULL);
+
+	fp = (memmap_file_state_t *) entity->info;
+
+	/* Assert that file position is valid for this write operation */
+	pos_after = fp->file_pos + length;
+	assert((pos_after >= fp->file_pos) && (pos_after <= fp->size));
+
+	memcpy((void *)((uintptr_t)(fp->base + fp->file_pos)),
+	       (void *)buffer, length);
+
+	*length_written = length;
+
+	/* Set file position after write */
+	fp->file_pos = pos_after;
+
+	return 0;
+}
+
+
+/* Close a file on the memmap device */
+static int memmap_block_close(io_entity_t *entity)
+{
+	assert(entity != NULL);
+
+	entity->info = 0;
+
+	/* This would be a mem free() if we had malloc.*/
+	zeromem((void *)&current_memmap_file, sizeof(current_memmap_file));
+
+	return 0;
+}
+
+
+/* Exported functions */
+
+/* Register the memmap driver with the IO abstraction */
+int register_io_dev_memmap(const io_dev_connector_t **dev_con)
+{
+	int result;
+	assert(dev_con != NULL);
+
+	result = io_register_device(&memmap_dev_info);
+	if (result == 0)
+		*dev_con = &memmap_dev_connector;
+
+	return result;
+}
diff --git a/drivers/io/io_mtd.c b/drivers/io/io_mtd.c
new file mode 100644
index 0000000..5d86592
--- /dev/null
+++ b/drivers/io/io_mtd.c
@@ -0,0 +1,290 @@
+/*
+ * Copyright (c) 2019-2022, ARM Limited and Contributors. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include <assert.h>
+#include <errno.h>
+#include <string.h>
+
+#include <common/debug.h>
+#include <drivers/io/io_driver.h>
+#include <drivers/io/io_mtd.h>
+#include <lib/utils.h>
+
+#include <platform_def.h>
+
+typedef struct {
+	io_mtd_dev_spec_t	*dev_spec;
+	uintptr_t		base;
+	unsigned long long	pos;		/* Offset in bytes */
+	unsigned long long	size;		/* Size of device in bytes */
+	unsigned long long	extra_offset;	/* Extra offset in bytes */
+} mtd_dev_state_t;
+
+io_type_t device_type_mtd(void);
+
+static int mtd_open(io_dev_info_t *dev_info, const uintptr_t spec,
+		    io_entity_t *entity);
+static int mtd_seek(io_entity_t *entity, int mode, signed long long offset);
+static int mtd_read(io_entity_t *entity, uintptr_t buffer, size_t length,
+		    size_t *length_read);
+static int mtd_close(io_entity_t *entity);
+static int mtd_dev_open(const uintptr_t dev_spec, io_dev_info_t **dev_info);
+static int mtd_dev_close(io_dev_info_t *dev_info);
+
+static const io_dev_connector_t mtd_dev_connector = {
+	.dev_open	= mtd_dev_open
+};
+
+static const io_dev_funcs_t mtd_dev_funcs = {
+	.type		= device_type_mtd,
+	.open		= mtd_open,
+	.seek		= mtd_seek,
+	.read		= mtd_read,
+	.close		= mtd_close,
+	.dev_close	= mtd_dev_close,
+};
+
+static mtd_dev_state_t state_pool[MAX_IO_MTD_DEVICES];
+static io_dev_info_t dev_info_pool[MAX_IO_MTD_DEVICES];
+
+io_type_t device_type_mtd(void)
+{
+	return IO_TYPE_MTD;
+}
+
+/* Locate a MTD state in the pool, specified by address */
+static int find_first_mtd_state(const io_mtd_dev_spec_t *dev_spec,
+				unsigned int *index_out)
+{
+	unsigned int index;
+	int result = -ENOENT;
+
+	for (index = 0U; index < MAX_IO_MTD_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 */
+static int allocate_dev_info(io_dev_info_t **dev_info)
+{
+	unsigned int index = 0U;
+	int result;
+
+	result = find_first_mtd_state(NULL, &index);
+	if (result != 0) {
+		return -ENOMEM;
+	}
+
+	dev_info_pool[index].funcs = &mtd_dev_funcs;
+	dev_info_pool[index].info = (uintptr_t)&state_pool[index];
+	*dev_info = &dev_info_pool[index];
+
+	return 0;
+}
+
+/* Release a device info from the pool */
+static int free_dev_info(io_dev_info_t *dev_info)
+{
+	int result;
+	unsigned int index = 0U;
+	mtd_dev_state_t *state;
+
+	state = (mtd_dev_state_t *)dev_info->info;
+	result = find_first_mtd_state(state->dev_spec, &index);
+	if (result != 0) {
+		return result;
+	}
+
+	zeromem(state, sizeof(mtd_dev_state_t));
+	zeromem(dev_info, sizeof(io_dev_info_t));
+
+	return 0;
+}
+
+static int mtd_add_extra_offset(mtd_dev_state_t *cur, size_t *extra_offset)
+{
+	io_mtd_ops_t *ops = &cur->dev_spec->ops;
+	int ret;
+
+	if (ops->seek == NULL) {
+		return 0;
+	}
+
+	ret = ops->seek(cur->base, cur->pos, extra_offset);
+	if (ret != 0) {
+		ERROR("%s: Seek error %d\n", __func__, ret);
+		return ret;
+	}
+
+	return 0;
+}
+
+static int mtd_open(io_dev_info_t *dev_info, const uintptr_t spec,
+		    io_entity_t *entity)
+{
+	mtd_dev_state_t *cur;
+	io_block_spec_t *region;
+	size_t extra_offset = 0U;
+	int ret;
+
+	assert((dev_info->info != 0UL) && (entity->info == 0UL));
+
+	region = (io_block_spec_t *)spec;
+	cur = (mtd_dev_state_t *)dev_info->info;
+	entity->info = (uintptr_t)cur;
+	cur->base = region->offset;
+	cur->pos = 0U;
+	cur->extra_offset = 0U;
+
+	ret = mtd_add_extra_offset(cur, &extra_offset);
+	if (ret != 0) {
+		return ret;
+	}
+
+	cur->base += extra_offset;
+
+	return 0;
+}
+
+/* Seek to a specific position using offset */
+static int mtd_seek(io_entity_t *entity, int mode, signed long long offset)
+{
+	mtd_dev_state_t *cur;
+	size_t extra_offset = 0U;
+	int ret;
+
+	assert((entity->info != (uintptr_t)NULL) && (offset >= 0));
+
+	cur = (mtd_dev_state_t *)entity->info;
+
+	switch (mode) {
+	case IO_SEEK_SET:
+		if ((offset >= 0) &&
+		    ((unsigned long long)offset >= cur->size)) {
+			return -EINVAL;
+		}
+
+		cur->pos = offset;
+		break;
+	case IO_SEEK_CUR:
+		if (((cur->base + cur->pos + (unsigned long long)offset) >=
+		     cur->size) ||
+		    ((cur->base + cur->pos + (unsigned long long)offset) <
+		     cur->base + cur->pos)) {
+			return -EINVAL;
+		}
+
+		cur->pos += (unsigned long long)offset;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	ret = mtd_add_extra_offset(cur, &extra_offset);
+	if (ret != 0) {
+		return ret;
+	}
+
+	cur->extra_offset = extra_offset;
+
+	return 0;
+}
+
+static int mtd_read(io_entity_t *entity, uintptr_t buffer, size_t length,
+		    size_t *out_length)
+{
+	mtd_dev_state_t *cur;
+	io_mtd_ops_t *ops;
+	int ret;
+
+	assert(entity->info != (uintptr_t)NULL);
+	assert((length > 0U) && (buffer != (uintptr_t)NULL));
+
+	cur = (mtd_dev_state_t *)entity->info;
+	ops = &cur->dev_spec->ops;
+	assert(ops->read != NULL);
+
+	VERBOSE("Read at %llx into %lx, length %zu\n",
+		cur->base + cur->pos, buffer, length);
+	if ((cur->base + cur->pos + length) > cur->dev_spec->device_size) {
+		return -EINVAL;
+	}
+
+	ret = ops->read(cur->base + cur->pos + cur->extra_offset, buffer,
+			length, out_length);
+	if (ret < 0) {
+		return ret;
+	}
+
+	assert(*out_length == length);
+	cur->pos += *out_length;
+
+	return 0;
+}
+
+static int mtd_close(io_entity_t *entity)
+{
+	entity->info = (uintptr_t)NULL;
+
+	return 0;
+}
+
+static int mtd_dev_open(const uintptr_t dev_spec, io_dev_info_t **dev_info)
+{
+	mtd_dev_state_t *cur;
+	io_dev_info_t *info;
+	io_mtd_ops_t *ops;
+	int result;
+
+	result = allocate_dev_info(&info);
+	if (result != 0) {
+		return -ENOENT;
+	}
+
+	cur = (mtd_dev_state_t *)info->info;
+	cur->dev_spec = (io_mtd_dev_spec_t *)dev_spec;
+	*dev_info = info;
+	ops = &(cur->dev_spec->ops);
+	if (ops->init != NULL) {
+		result = ops->init(&cur->dev_spec->device_size,
+				   &cur->dev_spec->erase_size);
+	}
+
+	if (result == 0) {
+		cur->size = cur->dev_spec->device_size;
+	} else {
+		cur->size = 0ULL;
+	}
+
+	return result;
+}
+
+static int mtd_dev_close(io_dev_info_t *dev_info)
+{
+	return free_dev_info(dev_info);
+}
+
+/* Exported functions */
+
+/* Register the MTD driver in the IO abstraction */
+int register_io_dev_mtd(const io_dev_connector_t **dev_con)
+{
+	int result;
+
+	result = io_register_device(&dev_info_pool[0]);
+	if (result == 0) {
+		*dev_con = &mtd_dev_connector;
+	}
+
+	return result;
+}
diff --git a/drivers/io/io_semihosting.c b/drivers/io/io_semihosting.c
new file mode 100644
index 0000000..1c2f84d
--- /dev/null
+++ b/drivers/io/io_semihosting.c
@@ -0,0 +1,201 @@
+/*
+ * Copyright (c) 2014-2020, ARM Limited and Contributors. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include <assert.h>
+
+#include <platform_def.h>
+
+#include <drivers/io/io_driver.h>
+#include <drivers/io/io_semihosting.h>
+#include <drivers/io/io_storage.h>
+#include <lib/semihosting.h>
+
+/* Identify the device type as semihosting */
+static io_type_t device_type_sh(void)
+{
+	return IO_TYPE_SEMIHOSTING;
+}
+
+
+/* Semi-hosting functions, device info and handle */
+
+static int sh_dev_open(const uintptr_t dev_spec, io_dev_info_t **dev_info);
+static int sh_file_open(io_dev_info_t *dev_info, const uintptr_t spec,
+		io_entity_t *entity);
+static int sh_file_seek(io_entity_t *entity, int mode, signed long long offset);
+static int sh_file_len(io_entity_t *entity, size_t *length);
+static int sh_file_read(io_entity_t *entity, uintptr_t buffer, size_t length,
+		size_t *length_read);
+static int sh_file_write(io_entity_t *entity, const uintptr_t buffer,
+		size_t length, size_t *length_written);
+static int sh_file_close(io_entity_t *entity);
+
+static const io_dev_connector_t sh_dev_connector = {
+	.dev_open = sh_dev_open
+};
+
+
+static const io_dev_funcs_t sh_dev_funcs = {
+	.type = device_type_sh,
+	.open = sh_file_open,
+	.seek = sh_file_seek,
+	.size = sh_file_len,
+	.read = sh_file_read,
+	.write = sh_file_write,
+	.close = sh_file_close,
+	.dev_init = NULL,	/* NOP */
+	.dev_close = NULL,	/* NOP */
+};
+
+
+static io_dev_info_t sh_dev_info = {
+	.funcs = &sh_dev_funcs,
+	.info = (uintptr_t)NULL
+};
+
+
+/* Open a connection to the semi-hosting device */
+static int sh_dev_open(const uintptr_t dev_spec __unused,
+		io_dev_info_t **dev_info)
+{
+	assert(dev_info != NULL);
+	*dev_info = &sh_dev_info;
+	return 0;
+}
+
+
+/* Open a file on the semi-hosting device */
+static int sh_file_open(io_dev_info_t *dev_info __unused,
+		const uintptr_t spec, io_entity_t *entity)
+{
+	int result = -ENOENT;
+	long sh_result;
+	const io_file_spec_t *file_spec = (const io_file_spec_t *)spec;
+
+	assert(file_spec != NULL);
+	assert(entity != NULL);
+
+	sh_result = semihosting_file_open(file_spec->path, file_spec->mode);
+
+	if (sh_result > 0) {
+		entity->info = (uintptr_t)sh_result;
+		result = 0;
+	}
+	return result;
+}
+
+
+/* Seek to a particular file offset on the semi-hosting device */
+static int sh_file_seek(io_entity_t *entity, int mode, signed long long offset)
+{
+	long file_handle, sh_result;
+
+	assert(entity != NULL);
+
+	file_handle = (long)entity->info;
+
+	sh_result = semihosting_file_seek(file_handle, (ssize_t)offset);
+
+	return (sh_result == 0) ? 0 : -ENOENT;
+}
+
+
+/* Return the size of a file on the semi-hosting device */
+static int sh_file_len(io_entity_t *entity, size_t *length)
+{
+	int result = -ENOENT;
+
+	assert(entity != NULL);
+	assert(length != NULL);
+
+	long sh_handle = (long)entity->info;
+	long sh_result = semihosting_file_length(sh_handle);
+
+	if (sh_result >= 0) {
+		result = 0;
+		*length = (size_t)sh_result;
+	}
+
+	return result;
+}
+
+
+/* Read data from a file on the semi-hosting device */
+static int sh_file_read(io_entity_t *entity, uintptr_t buffer, size_t length,
+		size_t *length_read)
+{
+	int result = -ENOENT;
+	long sh_result;
+	size_t bytes = length;
+	long file_handle;
+
+	assert(entity != NULL);
+	assert(length_read != NULL);
+
+	file_handle = (long)entity->info;
+
+	sh_result = semihosting_file_read(file_handle, &bytes, buffer);
+
+	if (sh_result >= 0) {
+		*length_read = (bytes != length) ? bytes : length;
+		result = 0;
+	}
+
+	return result;
+}
+
+
+/* Write data to a file on the semi-hosting device */
+static int sh_file_write(io_entity_t *entity, const uintptr_t buffer,
+		size_t length, size_t *length_written)
+{
+	long sh_result;
+	long file_handle;
+	size_t bytes = length;
+
+	assert(entity != NULL);
+	assert(length_written != NULL);
+
+	file_handle = (long)entity->info;
+
+	sh_result = semihosting_file_write(file_handle, &bytes, buffer);
+
+	*length_written = length - bytes;
+
+	return (sh_result == 0) ? 0 : -ENOENT;
+}
+
+
+/* Close a file on the semi-hosting device */
+static int sh_file_close(io_entity_t *entity)
+{
+	long sh_result;
+	long file_handle;
+
+	assert(entity != NULL);
+
+	file_handle = (long)entity->info;
+
+	sh_result = semihosting_file_close(file_handle);
+
+	return (sh_result >= 0) ? 0 : -ENOENT;
+}
+
+
+/* Exported functions */
+
+/* Register the semi-hosting driver with the IO abstraction */
+int register_io_dev_sh(const io_dev_connector_t **dev_con)
+{
+	int result;
+	assert(dev_con != NULL);
+
+	result = io_register_device(&sh_dev_info);
+	if (result == 0)
+		*dev_con = &sh_dev_connector;
+
+	return result;
+}
diff --git a/drivers/io/io_storage.c b/drivers/io/io_storage.c
new file mode 100644
index 0000000..0534268
--- /dev/null
+++ b/drivers/io/io_storage.c
@@ -0,0 +1,328 @@
+/*
+ * Copyright (c) 2014-2020, ARM Limited and Contributors. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include <assert.h>
+#include <stddef.h>
+
+#include <platform_def.h>
+
+#include <drivers/io/io_driver.h>
+#include <drivers/io/io_storage.h>
+
+/* Storage for a fixed maximum number of IO entities, definable by platform */
+static io_entity_t entity_pool[MAX_IO_HANDLES];
+
+/* Simple way of tracking used storage - each entry is NULL or a pointer to an
+ * entity */
+static io_entity_t *entity_map[MAX_IO_HANDLES];
+
+/* Track number of allocated entities */
+static unsigned int entity_count;
+
+/* Array of fixed maximum of registered devices, definable by platform */
+static const io_dev_info_t *devices[MAX_IO_DEVICES];
+
+/* Number of currently registered devices */
+static unsigned int dev_count;
+
+/* Extra validation functions only used when asserts are enabled */
+#if ENABLE_ASSERTIONS
+
+/* Return a boolean value indicating whether a device connector is valid */
+static bool is_valid_dev_connector(const io_dev_connector_t *dev_con)
+{
+	return (dev_con != NULL) && (dev_con->dev_open != NULL);
+}
+
+/* Return a boolean value indicating whether a device handle is valid */
+static bool is_valid_dev(const uintptr_t dev_handle)
+{
+	const io_dev_info_t *dev = (io_dev_info_t *)dev_handle;
+
+	return (dev != NULL) && (dev->funcs != NULL) &&
+			(dev->funcs->type != NULL) &&
+			(dev->funcs->type() < IO_TYPE_MAX);
+}
+
+
+/* Return a boolean value indicating whether an IO entity is valid */
+static bool is_valid_entity(const uintptr_t handle)
+{
+	const io_entity_t *entity = (io_entity_t *)handle;
+
+	return (entity != NULL) &&
+			(is_valid_dev((uintptr_t)entity->dev_handle));
+}
+
+
+/* Return a boolean value indicating whether a seek mode is valid */
+static bool is_valid_seek_mode(io_seek_mode_t mode)
+{
+	return ((mode != IO_SEEK_INVALID) && (mode < IO_SEEK_MAX));
+}
+
+#endif /* ENABLE_ASSERTIONS */
+/* End of extra validation functions only used when asserts are enabled */
+
+
+/* Open a connection to a specific device */
+static int io_storage_dev_open(const io_dev_connector_t *dev_con,
+		const uintptr_t dev_spec,
+		io_dev_info_t **dev_info)
+{
+	assert(dev_info != NULL);
+	assert(is_valid_dev_connector(dev_con));
+
+	return dev_con->dev_open(dev_spec, dev_info);
+}
+
+
+/* Set a handle to track an entity */
+static void set_handle(uintptr_t *handle, io_entity_t *entity)
+{
+	assert(handle != NULL);
+	*handle = (uintptr_t)entity;
+}
+
+
+/* Locate an entity in the pool, specified by address */
+static int find_first_entity(const io_entity_t *entity, unsigned int *index_out)
+{
+	int result = -ENOENT;
+	for (unsigned int index = 0; index < MAX_IO_HANDLES; ++index) {
+		if (entity_map[index] == entity) {
+			result = 0;
+			*index_out = index;
+			break;
+		}
+	}
+	return result;
+}
+
+
+/* Allocate an entity from the pool and return a pointer to it */
+static int allocate_entity(io_entity_t **entity)
+{
+	int result = -ENOMEM;
+	assert(entity != NULL);
+
+	if (entity_count < MAX_IO_HANDLES) {
+		unsigned int index = 0;
+		result = find_first_entity(NULL, &index);
+		assert(result == 0);
+		*entity = &entity_pool[index];
+		entity_map[index] = &entity_pool[index];
+		++entity_count;
+	}
+
+	return result;
+}
+
+
+/* Release an entity back to the pool */
+static int free_entity(const io_entity_t *entity)
+{
+	int result;
+	unsigned int index = 0;
+	assert(entity != NULL);
+
+	result = find_first_entity(entity, &index);
+	if (result ==  0) {
+		entity_map[index] = NULL;
+		--entity_count;
+	}
+
+	return result;
+}
+
+
+/* Exported API */
+
+/* Register a device driver */
+int io_register_device(const io_dev_info_t *dev_info)
+{
+	int result = -ENOMEM;
+	assert(dev_info != NULL);
+
+	if (dev_count < MAX_IO_DEVICES) {
+		devices[dev_count] = dev_info;
+		dev_count++;
+		result = 0;
+	}
+
+	return result;
+}
+
+
+/* Open a connection to an IO device */
+int io_dev_open(const io_dev_connector_t *dev_con, const uintptr_t dev_spec,
+		uintptr_t *handle)
+{
+	assert(handle != NULL);
+	return io_storage_dev_open(dev_con, dev_spec, (io_dev_info_t **)handle);
+}
+
+
+/* Initialise an IO device explicitly - to permit lazy initialisation or
+ * re-initialisation */
+int io_dev_init(uintptr_t dev_handle, const uintptr_t init_params)
+{
+	int result = 0;
+	assert(dev_handle != (uintptr_t)NULL);
+	assert(is_valid_dev(dev_handle));
+
+	io_dev_info_t *dev = (io_dev_info_t *)dev_handle;
+
+	/* Absence of registered function implies NOP here */
+	if (dev->funcs->dev_init != NULL) {
+		result = dev->funcs->dev_init(dev, init_params);
+	}
+
+	return result;
+}
+
+/* Close a connection to a device */
+int io_dev_close(uintptr_t dev_handle)
+{
+	int result = 0;
+	assert(dev_handle != (uintptr_t)NULL);
+	assert(is_valid_dev(dev_handle));
+
+	io_dev_info_t *dev = (io_dev_info_t *)dev_handle;
+
+	/* Absence of registered function implies NOP here */
+	if (dev->funcs->dev_close != NULL) {
+		result = dev->funcs->dev_close(dev);
+	}
+
+	return result;
+}
+
+
+/* Synchronous operations */
+
+
+/* Open an IO entity */
+int io_open(uintptr_t dev_handle, const uintptr_t spec, uintptr_t *handle)
+{
+	int result;
+	assert((spec != (uintptr_t)NULL) && (handle != NULL));
+	assert(is_valid_dev(dev_handle));
+
+	io_dev_info_t *dev = (io_dev_info_t *)dev_handle;
+	io_entity_t *entity;
+
+	result = allocate_entity(&entity);
+
+	if (result == 0) {
+		assert(dev->funcs->open != NULL);
+		result = dev->funcs->open(dev, spec, entity);
+
+		if (result == 0) {
+			entity->dev_handle = dev;
+			set_handle(handle, entity);
+		} else
+			free_entity(entity);
+	}
+	return result;
+}
+
+
+/* Seek to a specific position in an IO entity */
+int io_seek(uintptr_t handle, io_seek_mode_t mode, signed long long offset)
+{
+	int result = -ENODEV;
+	assert(is_valid_entity(handle) && is_valid_seek_mode(mode));
+
+	io_entity_t *entity = (io_entity_t *)handle;
+
+	io_dev_info_t *dev = entity->dev_handle;
+
+	if (dev->funcs->seek != NULL)
+		result = dev->funcs->seek(entity, mode, offset);
+
+	return result;
+}
+
+
+/* Determine the length of an IO entity */
+int io_size(uintptr_t handle, size_t *length)
+{
+	int result = -ENODEV;
+	assert(is_valid_entity(handle) && (length != NULL));
+
+	io_entity_t *entity = (io_entity_t *)handle;
+
+	io_dev_info_t *dev = entity->dev_handle;
+
+	if (dev->funcs->size != NULL)
+		result = dev->funcs->size(entity, length);
+
+	return result;
+}
+
+
+/* Read data from an IO entity */
+int io_read(uintptr_t handle,
+		uintptr_t buffer,
+		size_t length,
+		size_t *length_read)
+{
+	int result = -ENODEV;
+	assert(is_valid_entity(handle));
+
+	io_entity_t *entity = (io_entity_t *)handle;
+
+	io_dev_info_t *dev = entity->dev_handle;
+
+	if (dev->funcs->read != NULL)
+		result = dev->funcs->read(entity, buffer, length, length_read);
+
+	return result;
+}
+
+
+/* Write data to an IO entity */
+int io_write(uintptr_t handle,
+		const uintptr_t buffer,
+		size_t length,
+		size_t *length_written)
+{
+	int result = -ENODEV;
+	assert(is_valid_entity(handle));
+
+	io_entity_t *entity = (io_entity_t *)handle;
+
+	io_dev_info_t *dev = entity->dev_handle;
+
+	if (dev->funcs->write != NULL) {
+		result = dev->funcs->write(entity, buffer, length,
+				length_written);
+	}
+
+	return result;
+}
+
+
+/* Close an IO entity */
+int io_close(uintptr_t handle)
+{
+	int result = 0;
+	assert(is_valid_entity(handle));
+
+	io_entity_t *entity = (io_entity_t *)handle;
+
+	io_dev_info_t *dev = entity->dev_handle;
+
+	/* Absence of registered function implies NOP here */
+	if (dev->funcs->close != NULL)
+		result = dev->funcs->close(entity);
+
+	/* Ignore improbable free_entity failure */
+	(void)free_entity(entity);
+
+	return result;
+}