arm_ffa: introduce Arm FF-A support

Add Arm FF-A support implementing Arm Firmware Framework for Armv8-A v1.0

The Firmware Framework for Arm A-profile processors (FF-A v1.0) [1]
describes interfaces (ABIs) that standardize communication
between the Secure World and Normal World leveraging TrustZone
technology.

This driver uses 64-bit registers as per SMCCCv1.2 spec and comes
on top of the SMCCC layer. The driver provides the FF-A ABIs needed for
querying the FF-A framework from the secure world.

The driver uses SMC32 calling convention which means using the first
32-bit data of the Xn registers.

All supported ABIs come with their 32-bit version except FFA_RXTX_MAP
which has 64-bit version supported.

Both 32-bit and 64-bit direct messaging are supported which allows both
32-bit and 64-bit clients to use the FF-A bus.

FF-A is a discoverable bus and similar to architecture features.
FF-A bus is discovered using ARM_SMCCC_FEATURES mechanism performed
by the PSCI driver.

Clients are able to probe then use the FF-A bus by calling the DM class
searching APIs (e.g: uclass_first_device).

The Secure World is considered as one entity to communicate with
using the FF-A bus. FF-A communication is handled by one device and
one instance (the bus). This FF-A driver takes care of all the
interactions between Normal world and Secure World.

The driver exports its operations to be used by upper layers.

Exported operations:

- ffa_partition_info_get
- ffa_sync_send_receive
- ffa_rxtx_unmap

Generic FF-A methods are implemented in the Uclass (arm-ffa-uclass.c).
Arm specific methods are implemented in the Arm driver (arm-ffa.c).

For more details please refer to the driver documentation [2].

[1]: https://developer.arm.com/documentation/den0077/latest/
[2]: doc/arch/arm64.ffa.rst

Signed-off-by: Abdellatif El Khlifi <abdellatif.elkhlifi@arm.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Cc: Tom Rini <trini@konsulko.com>
Cc: Jens Wiklander <jens.wiklander@linaro.org>
Cc: Heinrich Schuchardt <xypron.glpk@gmx.de>

6 files changed, 1228 insertions, 0 deletions

diff --git a/drivers/firmware/Kconfig b/drivers/firmware/Kconfig
index eae1c8d..8789b1e 100644
--- a/drivers/firmware/Kconfig
+++ b/drivers/firmware/Kconfig
@@ -45,4 +45,5 @@ config ARM_SMCCC_FEATURES
 	  the PSCI driver is always probed and binds dirvers registered to the Arm SMCCC
 	  services if any and reported as supported by the SMCCC firmware.
 
+source "drivers/firmware/arm-ffa/Kconfig"
 source "drivers/firmware/scmi/Kconfig"
diff --git a/drivers/firmware/arm-ffa/Kconfig b/drivers/firmware/arm-ffa/Kconfig
new file mode 100644
index 0000000..9200c80
--- /dev/null
+++ b/drivers/firmware/arm-ffa/Kconfig
@@ -0,0 +1,36 @@
+# SPDX-License-Identifier: GPL-2.0
+
+config ARM_FFA_TRANSPORT
+	bool "Enable Arm Firmware Framework for Armv8-A driver"
+	depends on DM && ARM64
+	select ARM_SMCCC
+	select ARM_SMCCC_FEATURES
+	select LIB_UUID
+	select DEVRES
+	help
+	  The Firmware Framework for Arm A-profile processors (FF-A)
+	  describes interfaces (ABIs) that standardize communication
+	  between the Secure World and Normal World leveraging TrustZone
+	  technology.
+
+	  The FF-A support in U-Boot is based on FF-A specification v1.0 and uses SMC32
+	  calling convention.
+
+	  FF-A specification:
+
+	  https://developer.arm.com/documentation/den0077/a/?lang=en
+
+	  In U-Boot FF-A design, FF-A is considered as a discoverable bus.
+	  FF-A bus is discovered using ARM_SMCCC_FEATURES mechanism performed
+	  by the PSCI driver.
+	  The Secure World is considered as one entity to communicate with
+	  using the FF-A bus.
+	  FF-A communication is handled by one device and one instance (the bus).
+	  The FF-A support on U-Boot  takes care of all the interactions between Normal
+	  world and Secure World.
+
+	  Generic FF-A methods are implemented in the Uclass (arm-ffa-uclass.c).
+	  Arm specific methods are implemented in the Arm driver (arm-ffa.c).
+
+	  For more details about the FF-A support, please refer to doc/arch/arm64.ffa.rst
+
diff --git a/drivers/firmware/arm-ffa/Makefile b/drivers/firmware/arm-ffa/Makefile
new file mode 100644
index 0000000..11b1766
--- /dev/null
+++ b/drivers/firmware/arm-ffa/Makefile
@@ -0,0 +1,8 @@
+# SPDX-License-Identifier: GPL-2.0+
+#
+# Copyright 2022-2023 Arm Limited and/or its affiliates <open-source-office@arm.com>
+#
+# Authors:
+#   Abdellatif El Khlifi <abdellatif.elkhlifi@arm.com>
+
+obj-y += arm-ffa-uclass.o arm-ffa.o
diff --git a/drivers/firmware/arm-ffa/arm-ffa-uclass.c b/drivers/firmware/arm-ffa/arm-ffa-uclass.c
new file mode 100644
index 0000000..ffa9d81
--- /dev/null
+++ b/drivers/firmware/arm-ffa/arm-ffa-uclass.c
@@ -0,0 +1,1065 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright 2022-2023 Arm Limited and/or its affiliates <open-source-office@arm.com>
+ *
+ * Authors:
+ *   Abdellatif El Khlifi <abdellatif.elkhlifi@arm.com>
+ */
+#include <common.h>
+#include <arm_ffa.h>
+#include <arm_ffa_priv.h>
+#include <dm.h>
+#include <log.h>
+#include <malloc.h>
+#include <string.h>
+#include <uuid.h>
+#include <asm/global_data.h>
+#include <dm/device-internal.h>
+#include <dm/devres.h>
+#include <dm/root.h>
+#include <linux/errno.h>
+#include <linux/sizes.h>
+
+DECLARE_GLOBAL_DATA_PTR;
+
+/* Error mapping declarations */
+
+int ffa_to_std_errmap[MAX_NUMBER_FFA_ERR] = {
+	[NOT_SUPPORTED] = -EOPNOTSUPP,
+	[INVALID_PARAMETERS] = -EINVAL,
+	[NO_MEMORY] = -ENOMEM,
+	[BUSY] = -EBUSY,
+	[INTERRUPTED] = -EINTR,
+	[DENIED] = -EACCES,
+	[RETRY] = -EAGAIN,
+	[ABORTED] = -ECANCELED,
+};
+
+static struct ffa_abi_errmap err_msg_map[FFA_ERRMAP_COUNT] = {
+	[FFA_ID_TO_ERRMAP_ID(FFA_VERSION)] = {
+		{
+			[NOT_SUPPORTED] =
+			"NOT_SUPPORTED: A Firmware Framework implementation does not exist",
+		},
+	},
+	[FFA_ID_TO_ERRMAP_ID(FFA_ID_GET)] = {
+		{
+			[NOT_SUPPORTED] =
+			"NOT_SUPPORTED: This function is not implemented at this FF-A instance",
+		},
+	},
+	[FFA_ID_TO_ERRMAP_ID(FFA_FEATURES)] = {
+		{
+			[NOT_SUPPORTED] =
+			"NOT_SUPPORTED: FFA_RXTX_MAP is not implemented at this FF-A instance",
+		},
+	},
+	[FFA_ID_TO_ERRMAP_ID(FFA_PARTITION_INFO_GET)] = {
+		{
+			[NOT_SUPPORTED] =
+			"NOT_SUPPORTED: This function is not implemented at this FF-A instance",
+			[INVALID_PARAMETERS] =
+			"INVALID_PARAMETERS: Unrecognized UUID",
+			[NO_MEMORY] =
+			"NO_MEMORY: Results cannot fit in RX buffer of the caller",
+			[BUSY] =
+			"BUSY: RX buffer of the caller is not free",
+			[DENIED] =
+			"DENIED: Callee is not in a state to handle this request",
+		},
+	},
+	[FFA_ID_TO_ERRMAP_ID(FFA_RXTX_UNMAP)] = {
+		{
+			[NOT_SUPPORTED] =
+			"NOT_SUPPORTED: FFA_RXTX_UNMAP is not implemented at this FF-A instance",
+			[INVALID_PARAMETERS] =
+			"INVALID_PARAMETERS: No buffer pair registered on behalf of the caller",
+		},
+	},
+	[FFA_ID_TO_ERRMAP_ID(FFA_RX_RELEASE)] = {
+		{
+			[NOT_SUPPORTED] =
+			"NOT_SUPPORTED: FFA_RX_RELEASE is not implemented at this FF-A instance",
+			[DENIED] =
+			"DENIED: Caller did not have ownership of the RX buffer",
+		},
+	},
+	[FFA_ID_TO_ERRMAP_ID(FFA_RXTX_MAP)] = {
+		{
+			[NOT_SUPPORTED] =
+			"NOT_SUPPORTED: This function is not implemented at this FF-A instance",
+			[INVALID_PARAMETERS] =
+			"INVALID_PARAMETERS: Field(s) in input parameters incorrectly encoded",
+			[NO_MEMORY] =
+			"NO_MEMORY: Not enough memory",
+			[DENIED] =
+			"DENIED: Buffer pair already registered",
+		},
+	},
+};
+
+/**
+ * ffa_to_std_errno() - convert FF-A error code to standard error code
+ * @ffa_errno:	Error code returned by the FF-A ABI
+ *
+ * Map the given FF-A error code as specified
+ * by the spec to a u-boot standard error code.
+ *
+ * Return:
+ *
+ * The standard error code on success. . Otherwise, failure
+ */
+static int ffa_to_std_errno(int ffa_errno)
+{
+	int err_idx = -ffa_errno;
+
+	/* Map the FF-A error code to the standard u-boot error code */
+	if (err_idx > 0 && err_idx < MAX_NUMBER_FFA_ERR)
+		return ffa_to_std_errmap[err_idx];
+	return -EINVAL;
+}
+
+/**
+ * ffa_print_error_log() - print the error log corresponding to the selected FF-A ABI
+ * @ffa_id:	FF-A ABI ID
+ * @ffa_errno:	Error code returned by the FF-A ABI
+ *
+ * Map the FF-A error code to the error log relevant to the
+ * selected FF-A ABI. Then the error log is printed.
+ *
+ * Return:
+ *
+ * 0 on success. . Otherwise, failure
+ */
+static int ffa_print_error_log(u32 ffa_id, int ffa_errno)
+{
+	int err_idx = -ffa_errno, abi_idx = 0;
+
+	/* Map the FF-A error code to the corresponding error log */
+
+	if (err_idx <= 0 || err_idx >= MAX_NUMBER_FFA_ERR)
+		return -EINVAL;
+
+	if (ffa_id < FFA_FIRST_ID || ffa_id > FFA_LAST_ID)
+		return -EINVAL;
+
+	abi_idx = FFA_ID_TO_ERRMAP_ID(ffa_id);
+	if (abi_idx < 0 || abi_idx >= FFA_ERRMAP_COUNT)
+		return -EINVAL;
+
+	if (!err_msg_map[abi_idx].err_str[err_idx])
+		return -EINVAL;
+
+	log_err("%s\n", err_msg_map[abi_idx].err_str[err_idx]);
+
+	return 0;
+}
+
+/* FF-A ABIs implementation (U-Boot side) */
+
+/**
+ * invoke_ffa_fn() - SMC wrapper
+ * @args: FF-A ABI arguments to be copied to Xn registers
+ * @res: FF-A ABI return data to be copied from Xn registers
+ *
+ * Calls low level SMC implementation.
+ * This function should be implemented by the user driver.
+ */
+void __weak invoke_ffa_fn(ffa_value_t args, ffa_value_t *res)
+{
+}
+
+/**
+ * ffa_get_version_hdlr() - FFA_VERSION handler function
+ * @dev: The FF-A bus device
+ *
+ * Implement FFA_VERSION FF-A function
+ * to get from the secure world the FF-A framework version
+ * FFA_VERSION is used to discover the FF-A framework.
+ *
+ * Return:
+ *
+ * 0 on success. Otherwise, failure
+ */
+int ffa_get_version_hdlr(struct udevice *dev)
+{
+	u16 major, minor;
+	ffa_value_t res = {0};
+	int ffa_errno;
+	struct ffa_priv *uc_priv;
+
+	invoke_ffa_fn((ffa_value_t){
+			.a0 = FFA_SMC_32(FFA_VERSION), .a1 = FFA_VERSION_1_0,
+			}, &res);
+
+	ffa_errno = res.a0;
+	if (ffa_errno < 0) {
+		ffa_print_error_log(FFA_VERSION, ffa_errno);
+		return ffa_to_std_errno(ffa_errno);
+	}
+
+	major = GET_FFA_MAJOR_VERSION(res.a0);
+	minor = GET_FFA_MINOR_VERSION(res.a0);
+
+	log_info("FF-A driver %d.%d\nFF-A framework %d.%d\n",
+		 FFA_MAJOR_VERSION, FFA_MINOR_VERSION, major, minor);
+
+	if (major == FFA_MAJOR_VERSION && minor >= FFA_MINOR_VERSION) {
+		log_info("FF-A versions are compatible\n");
+
+		if (dev) {
+			uc_priv = dev_get_uclass_priv(dev);
+			if (uc_priv)
+				uc_priv->fwk_version = res.a0;
+		}
+
+		return 0;
+	}
+
+	log_err("versions are incompatible\nExpected: %d.%d , Found: %d.%d\n",
+		FFA_MAJOR_VERSION, FFA_MINOR_VERSION, major, minor);
+
+	return -EPROTONOSUPPORT;
+}
+
+/**
+ * ffa_get_endpoint_id() - FFA_ID_GET handler function
+ * @dev: The FF-A bus device
+ *
+ * Implement FFA_ID_GET FF-A function
+ * to get from the secure world u-boot endpoint ID
+ *
+ * Return:
+ *
+ * 0 on success. Otherwise, failure
+ */
+static int ffa_get_endpoint_id(struct udevice *dev)
+{
+	ffa_value_t res = {0};
+	int ffa_errno;
+	struct ffa_priv *uc_priv = dev_get_uclass_priv(dev);
+
+	invoke_ffa_fn((ffa_value_t){
+			.a0 = FFA_SMC_32(FFA_ID_GET),
+			}, &res);
+
+	if (res.a0 == FFA_SMC_32(FFA_SUCCESS)) {
+		uc_priv->id = GET_SELF_ENDPOINT_ID((u32)res.a2);
+		log_debug("FF-A endpoint ID is %u\n", uc_priv->id);
+
+		return 0;
+	}
+
+	ffa_errno = res.a2;
+
+	ffa_print_error_log(FFA_ID_GET, ffa_errno);
+
+	return ffa_to_std_errno(ffa_errno);
+}
+
+/**
+ * ffa_set_rxtx_buffers_pages_cnt() - set the minimum number of pages in each of the RX/TX buffers
+ * @dev: The FF-A bus device
+ * @prop_field: properties field obtained from FFA_FEATURES ABI
+ *
+ * Set the minimum number of pages in each of the RX/TX buffers in uc_priv
+ *
+ * Return:
+ *
+ * rxtx_min_pages field contains the returned number of pages
+ * 0 on success. Otherwise, failure
+ */
+static int ffa_set_rxtx_buffers_pages_cnt(struct udevice *dev, u32 prop_field)
+{
+	struct ffa_priv *uc_priv = dev_get_uclass_priv(dev);
+
+	switch (prop_field) {
+	case RXTX_4K:
+		uc_priv->pair.rxtx_min_pages = 1;
+		break;
+	case RXTX_16K:
+		uc_priv->pair.rxtx_min_pages = 4;
+		break;
+	case RXTX_64K:
+		uc_priv->pair.rxtx_min_pages = 16;
+		break;
+	default:
+		log_err("RX/TX buffer size not supported\n");
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+/**
+ * ffa_get_rxtx_map_features_hdlr() - FFA_FEATURES handler function with FFA_RXTX_MAP argument
+ * @dev: The FF-A bus device
+ *
+ * Implement FFA_FEATURES FF-A function to retrieve the FFA_RXTX_MAP features
+ *
+ * Return:
+ *
+ * 0 on success. Otherwise, failure
+ */
+static int ffa_get_rxtx_map_features_hdlr(struct udevice *dev)
+{
+	ffa_value_t res = {0};
+	int ffa_errno;
+
+	invoke_ffa_fn((ffa_value_t){
+			.a0 = FFA_SMC_32(FFA_FEATURES),
+			.a1 = FFA_SMC_64(FFA_RXTX_MAP),
+			}, &res);
+
+	if (res.a0 == FFA_SMC_32(FFA_SUCCESS))
+		return ffa_set_rxtx_buffers_pages_cnt(dev, res.a2);
+
+	ffa_errno = res.a2;
+	ffa_print_error_log(FFA_FEATURES, ffa_errno);
+
+	return ffa_to_std_errno(ffa_errno);
+}
+
+/**
+ * ffa_free_rxtx_buffers() - free the RX/TX buffers
+ * @dev: The FF-A bus device
+ *
+ * Free the RX/TX buffers
+ */
+static void ffa_free_rxtx_buffers(struct udevice *dev)
+{
+	struct ffa_priv *uc_priv = dev_get_uclass_priv(dev);
+
+	log_debug("Freeing FF-A RX/TX buffers\n");
+
+	if (uc_priv->pair.rxbuf) {
+		free(uc_priv->pair.rxbuf);
+		uc_priv->pair.rxbuf = NULL;
+	}
+
+	if (uc_priv->pair.txbuf) {
+		free(uc_priv->pair.txbuf);
+		uc_priv->pair.txbuf = NULL;
+	}
+}
+
+/**
+ * ffa_alloc_rxtx_buffers() - allocate the RX/TX buffers
+ * @dev: The FF-A bus device
+ *
+ * Used by ffa_map_rxtx_buffers to allocate
+ * the RX/TX buffers before mapping them. The allocated memory is physically
+ * contiguous since memalign ends up calling malloc which allocates
+ * contiguous memory in u-boot.
+ * The size of the memory allocated is the minimum allowed.
+ *
+ * Return:
+ *
+ * 0 on success. Otherwise, failure
+ */
+static int ffa_alloc_rxtx_buffers(struct udevice *dev)
+{
+	u64 bytes;
+	struct ffa_priv *uc_priv = dev_get_uclass_priv(dev);
+
+	log_debug("Using %lu 4KB page(s) for FF-A RX/TX buffers size\n",
+		  uc_priv->pair.rxtx_min_pages);
+
+	bytes = uc_priv->pair.rxtx_min_pages * SZ_4K;
+
+	/*
+	 * The alignment of the RX and TX buffers must be equal
+	 * to the larger translation granule size
+	 * Assumption: Memory allocated with memalign is always physically contiguous
+	 */
+
+	uc_priv->pair.rxbuf = memalign(bytes, bytes);
+	if (!uc_priv->pair.rxbuf) {
+		log_err("failure to allocate RX buffer\n");
+		return -ENOBUFS;
+	}
+
+	log_debug("FF-A RX buffer at virtual address %p\n", uc_priv->pair.rxbuf);
+
+	uc_priv->pair.txbuf = memalign(bytes, bytes);
+	if (!uc_priv->pair.txbuf) {
+		free(uc_priv->pair.rxbuf);
+		uc_priv->pair.rxbuf = NULL;
+		log_err("failure to allocate the TX buffer\n");
+		return -ENOBUFS;
+	}
+
+	log_debug("FF-A TX buffer at virtual address %p\n", uc_priv->pair.txbuf);
+
+	/* Make sure the buffers are cleared before use */
+	memset(uc_priv->pair.rxbuf, 0, bytes);
+	memset(uc_priv->pair.txbuf, 0, bytes);
+
+	return 0;
+}
+
+/**
+ * ffa_map_rxtx_buffers_hdlr() - FFA_RXTX_MAP handler function
+ * @dev: The FF-A bus device
+ *
+ * Implement FFA_RXTX_MAP FF-A function to map the RX/TX buffers
+ *
+ * Return:
+ *
+ * 0 on success. Otherwise, failure
+ */
+static int ffa_map_rxtx_buffers_hdlr(struct udevice *dev)
+{
+	int ret;
+	ffa_value_t res = {0};
+	int ffa_errno;
+	struct ffa_priv *uc_priv = dev_get_uclass_priv(dev);
+
+	ret = ffa_alloc_rxtx_buffers(dev);
+	if (ret)
+		return ret;
+
+	/*
+	 * we need to pass the physical addresses of the RX/TX buffers
+	 * in u-boot physical/virtual mapping is 1:1
+	 * no need to convert from virtual to physical
+	 */
+
+	invoke_ffa_fn((ffa_value_t){
+			.a0 = FFA_SMC_64(FFA_RXTX_MAP),
+			.a1 = map_to_sysmem(uc_priv->pair.txbuf),
+			.a2 = map_to_sysmem(uc_priv->pair.rxbuf),
+			.a3 = uc_priv->pair.rxtx_min_pages,
+			}, &res);
+
+	if (res.a0 == FFA_SMC_32(FFA_SUCCESS)) {
+		log_debug("FF-A RX/TX buffers mapped\n");
+		return 0;
+	}
+
+	ffa_errno = res.a2;
+	ffa_print_error_log(FFA_RXTX_MAP, ffa_errno);
+
+	ffa_free_rxtx_buffers(dev);
+
+	return ffa_to_std_errno(ffa_errno);
+}
+
+/**
+ * ffa_unmap_rxtx_buffers_hdlr() - FFA_RXTX_UNMAP handler function
+ * @dev: The FF-A bus device
+ *
+ * Implement FFA_RXTX_UNMAP FF-A function to unmap the RX/TX buffers
+ *
+ * Return:
+ *
+ * 0 on success. Otherwise, failure
+ */
+int ffa_unmap_rxtx_buffers_hdlr(struct udevice *dev)
+{
+	ffa_value_t res = {0};
+	int ffa_errno;
+	struct ffa_priv *uc_priv;
+
+	log_debug("unmapping FF-A RX/TX buffers\n");
+
+	uc_priv = dev_get_uclass_priv(dev);
+
+	invoke_ffa_fn((ffa_value_t){
+			.a0 = FFA_SMC_32(FFA_RXTX_UNMAP),
+			.a1 = PREP_SELF_ENDPOINT_ID(uc_priv->id),
+			}, &res);
+
+	if (res.a0 == FFA_SMC_32(FFA_SUCCESS)) {
+		ffa_free_rxtx_buffers(dev);
+		return 0;
+	}
+
+	ffa_errno = res.a2;
+	ffa_print_error_log(FFA_RXTX_UNMAP, ffa_errno);
+
+	return ffa_to_std_errno(ffa_errno);
+}
+
+/**
+ * ffa_release_rx_buffer_hdlr() - FFA_RX_RELEASE handler function
+ * @dev: The FF-A bus device
+ *
+ * Invoke FFA_RX_RELEASE FF-A function to release the ownership of the RX buffer
+ *
+ * Return:
+ *
+ * 0 on success. Otherwise, failure
+ */
+static int ffa_release_rx_buffer_hdlr(struct udevice *dev)
+{
+	ffa_value_t res = {0};
+	int ffa_errno;
+
+	invoke_ffa_fn((ffa_value_t){
+			.a0 = FFA_SMC_32(FFA_RX_RELEASE),
+			}, &res);
+
+	if (res.a0 == FFA_SMC_32(FFA_SUCCESS))
+		return 0;
+
+	ffa_errno = res.a2;
+	ffa_print_error_log(FFA_RX_RELEASE, ffa_errno);
+
+	return ffa_to_std_errno(ffa_errno);
+}
+
+/**
+ * ffa_uuid_are_identical() - check whether two given UUIDs are identical
+ * @uuid1: first UUID
+ * @uuid2: second UUID
+ *
+ * Used by ffa_read_partitions_info to search for a UUID in the partitions descriptors table
+ *
+ * Return:
+ *
+ * 1 when UUIDs match. Otherwise, 0
+ */
+static bool ffa_uuid_are_identical(const struct ffa_partition_uuid *uuid1,
+				   const struct ffa_partition_uuid *uuid2)
+{
+	if (!uuid1 || !uuid2)
+		return 0;
+
+	return !memcmp(uuid1, uuid2, sizeof(struct ffa_partition_uuid));
+}
+
+/**
+ * ffa_read_partitions_info() - read queried partition data
+ * @dev: The FF-A bus device
+ * @count: The number of partitions queried
+ * @part_uuid: Pointer to the partition(s) UUID
+ *
+ * Read the partitions information returned by the FFA_PARTITION_INFO_GET and saves it in uc_priv
+ *
+ * Return:
+ *
+ * uc_priv is updated with the partition(s) information
+ * 0 is returned on success. Otherwise, failure
+ */
+static int ffa_read_partitions_info(struct udevice *dev, u32 count,
+				    struct ffa_partition_uuid *part_uuid)
+{
+	struct ffa_priv *uc_priv = dev_get_uclass_priv(dev);
+
+	if (!count) {
+		log_err("no partition detected\n");
+		return -ENODATA;
+	}
+
+	log_debug("Reading FF-A partitions data from the RX buffer\n");
+
+	if (!part_uuid) {
+		/* Querying information of all partitions */
+		u64 buf_bytes;
+		u64 data_bytes;
+		u32 desc_idx;
+		struct ffa_partition_info *parts_info;
+
+		data_bytes = count * sizeof(struct ffa_partition_desc);
+
+		buf_bytes = uc_priv->pair.rxtx_min_pages * SZ_4K;
+
+		if (data_bytes > buf_bytes) {
+			log_err("partitions data size exceeds the RX buffer size:\n");
+			log_err("    sizes in bytes: data %llu , RX buffer %llu\n",
+				data_bytes,
+				buf_bytes);
+
+			return -ENOMEM;
+		}
+
+		uc_priv->partitions.descs = devm_kmalloc(dev, data_bytes, __GFP_ZERO);
+		if (!uc_priv->partitions.descs) {
+			log_err("cannot  allocate partitions data buffer\n");
+			return -ENOMEM;
+		}
+
+		parts_info = uc_priv->pair.rxbuf;
+
+		for (desc_idx = 0 ; desc_idx < count ; desc_idx++) {
+			uc_priv->partitions.descs[desc_idx].info =
+				parts_info[desc_idx];
+
+			log_debug("FF-A partition ID %x : info cached\n",
+				  uc_priv->partitions.descs[desc_idx].info.id);
+		}
+
+		uc_priv->partitions.count = count;
+
+		log_debug("%d FF-A partition(s) found and cached\n", count);
+
+	} else {
+		u32 rx_desc_idx, cached_desc_idx;
+		struct ffa_partition_info *parts_info;
+		u8 desc_found;
+
+		parts_info = uc_priv->pair.rxbuf;
+
+		/*
+		 * Search for the SP IDs read from the RX buffer
+		 * in the already cached SPs.
+		 * Update the UUID when ID found.
+		 */
+		for (rx_desc_idx = 0; rx_desc_idx < count ; rx_desc_idx++) {
+			desc_found = 0;
+
+			/* Search the current ID in the cached partitions */
+			for (cached_desc_idx = 0;
+			     cached_desc_idx < uc_priv->partitions.count;
+			     cached_desc_idx++) {
+				/* Save the UUID */
+				if (uc_priv->partitions.descs[cached_desc_idx].info.id ==
+				    parts_info[rx_desc_idx].id) {
+					uc_priv->partitions.descs[cached_desc_idx].sp_uuid =
+						*part_uuid;
+
+					desc_found = 1;
+					break;
+				}
+			}
+
+			if (!desc_found)
+				return -ENODATA;
+		}
+	}
+
+	return  0;
+}
+
+/**
+ * ffa_query_partitions_info() - invoke FFA_PARTITION_INFO_GET and save partitions data
+ * @dev: The FF-A bus device
+ * @part_uuid: Pointer to the partition(s) UUID
+ * @pcount: Pointer to the number of partitions variable filled when querying
+ *
+ * Execute the FFA_PARTITION_INFO_GET to query the partitions data.
+ * Then, call ffa_read_partitions_info to save the data in uc_priv.
+ *
+ * After reading the data the RX buffer is released using ffa_release_rx_buffer
+ *
+ * Return:
+ *
+ * When part_uuid is NULL, all partitions data are retrieved from secure world
+ * When part_uuid is non NULL, data for partitions matching the given UUID are
+ * retrieved and the number of partitions is returned
+ * 0 is returned on success. Otherwise, failure
+ */
+static int ffa_query_partitions_info(struct udevice *dev, struct ffa_partition_uuid *part_uuid,
+				     u32 *pcount)
+{
+	struct ffa_partition_uuid query_uuid = {0};
+	ffa_value_t res = {0};
+	int ffa_errno;
+
+	/*
+	 * If a UUID is specified. Information for one or more
+	 * partitions in the system is queried. Otherwise, information
+	 * for all installed partitions is queried
+	 */
+
+	if (part_uuid) {
+		if (!pcount)
+			return -EINVAL;
+
+		query_uuid = *part_uuid;
+	} else if (pcount) {
+		return -EINVAL;
+	}
+
+	invoke_ffa_fn((ffa_value_t){
+			.a0 = FFA_SMC_32(FFA_PARTITION_INFO_GET),
+			.a1 = query_uuid.a1,
+			.a2 = query_uuid.a2,
+			.a3 = query_uuid.a3,
+			.a4 = query_uuid.a4,
+			}, &res);
+
+	if (res.a0 == FFA_SMC_32(FFA_SUCCESS)) {
+		int ret;
+
+		/*
+		 * res.a2 contains the count of partition information descriptors
+		 * populated in the RX buffer
+		 */
+		if (res.a2) {
+			ret = ffa_read_partitions_info(dev, (u32)res.a2, part_uuid);
+			if (ret) {
+				log_err("failed reading SP(s) data , err (%d)\n", ret);
+				ffa_release_rx_buffer_hdlr(dev);
+				return -EINVAL;
+			}
+		}
+
+		/* Return the SP count (when querying using a UUID) */
+		if (pcount)
+			*pcount = (u32)res.a2;
+
+		/*
+		 * After calling FFA_PARTITION_INFO_GET the buffer ownership
+		 * is assigned to the consumer (u-boot). So, we need to give
+		 * the ownership back to the SPM or hypervisor
+		 */
+		ret = ffa_release_rx_buffer_hdlr(dev);
+
+		return ret;
+	}
+
+	ffa_errno = res.a2;
+	ffa_print_error_log(FFA_PARTITION_INFO_GET, ffa_errno);
+
+	return ffa_to_std_errno(ffa_errno);
+}
+
+/**
+ * ffa_get_partitions_info_hdlr() - FFA_PARTITION_INFO_GET handler function
+ *	@uuid_str: pointer to the UUID string
+ *	@sp_count: address of the variable containing the number of partitions matching the UUID
+ *			 The variable is set by the driver
+ *	@sp_descs: address of the descriptors of the partitions matching the UUID
+ *			 The address is set by the driver
+ *
+ * Return the number of partitions and their descriptors matching the UUID
+ *
+ * Query the secure partition data from uc_priv.
+ * If not found, invoke FFA_PARTITION_INFO_GET FF-A function to query the partition information
+ * from secure world.
+ *
+ * A client of the FF-A driver should know the UUID of the service it wants to
+ * access. It should use the UUID to request the FF-A driver to provide the
+ * partition(s) information of the service. The FF-A driver uses
+ * PARTITION_INFO_GET to obtain this information. This is implemented through
+ * ffa_get_partitions_info_hdlr() function.
+ * If the partition(s) matching the UUID found, the partition(s) information and the
+ * number are returned.
+ * If no partition matching the UUID is found in the cached area, a new FFA_PARTITION_INFO_GET
+ * call is issued.
+ * If not done yet, the UUID is updated in the cached area.
+ * This assumes that partitions data does not change in the secure world.
+ * Otherwise u-boot will have an outdated partition data. The benefit of caching
+ * the information in the FF-A driver is to accommodate discovery after
+ * ExitBootServices().
+ *
+ * Return:
+ *
+ * @sp_count: the number of partitions
+ * @sp_descs: address of the partitions descriptors
+ *
+ * On success 0 is returned. Otherwise, failure
+ */
+int ffa_get_partitions_info_hdlr(struct udevice *dev, const char *uuid_str,
+				 u32 *sp_count, struct ffa_partition_desc **sp_descs)
+{
+	u32 i;
+	struct ffa_partition_uuid part_uuid = {0};
+	struct ffa_priv *uc_priv;
+	struct ffa_partition_desc *rx_descs;
+
+	uc_priv = dev_get_uclass_priv(dev);
+
+	if (!uc_priv->partitions.count || !uc_priv->partitions.descs) {
+		log_err("no partition installed\n");
+		return -EINVAL;
+	}
+
+	if (!uuid_str) {
+		log_err("no UUID provided\n");
+		return -EINVAL;
+	}
+
+	if (!sp_count) {
+		log_err("no count argument provided\n");
+		return -EINVAL;
+	}
+
+	if (!sp_descs) {
+		log_err("no info argument provided\n");
+		return -EINVAL;
+	}
+
+	if (uuid_str_to_le_bin(uuid_str, (unsigned char *)&part_uuid)) {
+		log_err("invalid UUID\n");
+		return -EINVAL;
+	}
+
+	log_debug("Searching FF-A partitions using the provided UUID\n");
+
+	*sp_count = 0;
+	*sp_descs = uc_priv->pair.rxbuf;
+	rx_descs = *sp_descs;
+
+	/* Search in the cached partitions */
+	for (i = 0; i < uc_priv->partitions.count; i++)
+		if (ffa_uuid_are_identical(&uc_priv->partitions.descs[i].sp_uuid,
+					   &part_uuid)) {
+			log_debug("FF-A partition ID %x matches the provided UUID\n",
+				  uc_priv->partitions.descs[i].info.id);
+
+			(*sp_count)++;
+			*rx_descs++ = uc_priv->partitions.descs[i];
+			}
+
+	if (!(*sp_count)) {
+		int ret;
+
+		log_debug("No FF-A partition found. Querying framework ...\n");
+
+		ret = ffa_query_partitions_info(dev, &part_uuid, sp_count);
+
+		if (!ret) {
+			log_debug("Number of FF-A partition(s) matching the UUID: %d\n", *sp_count);
+
+			if (*sp_count)
+				ret = ffa_get_partitions_info_hdlr(dev, uuid_str, sp_count,
+								   sp_descs);
+			else
+				ret = -ENODATA;
+		}
+
+		return ret;
+	}
+
+	return 0;
+}
+
+/**
+ * ffa_cache_partitions_info() - Query and saves all secure partitions data
+ * @dev: The FF-A bus device
+ *
+ * Invoke FFA_PARTITION_INFO_GET FF-A function to query from secure world
+ * all partitions information.
+ *
+ * The FFA_PARTITION_INFO_GET call is issued with nil UUID as an argument.
+ * All installed partitions information are returned. We cache them in uc_priv
+ * and we keep the UUID field empty (in FF-A 1.0 UUID is not provided by the partition descriptor)
+ *
+ * Called at the device probing level.
+ * ffa_cache_partitions_info uses ffa_query_partitions_info to get the data
+ *
+ * Return:
+ *
+ * 0 on success. Otherwise, failure
+ */
+static int ffa_cache_partitions_info(struct udevice *dev)
+{
+	return ffa_query_partitions_info(dev, NULL, NULL);
+}
+
+/**
+ * ffa_msg_send_direct_req_hdlr() - FFA_MSG_SEND_DIRECT_{REQ,RESP} handler function
+ * @dev: The FF-A bus device
+ * @dst_part_id: destination partition ID
+ * @msg: pointer to the message data preallocated by the client (in/out)
+ * @is_smc64: select 64-bit or 32-bit FF-A ABI
+ *
+ * Implement FFA_MSG_SEND_DIRECT_{REQ,RESP}
+ * FF-A functions.
+ *
+ * FFA_MSG_SEND_DIRECT_REQ is used to send the data to the secure partition.
+ * The response from the secure partition is handled by reading the
+ * FFA_MSG_SEND_DIRECT_RESP arguments.
+ *
+ * The maximum size of the data that can be exchanged is 40 bytes which is
+ * sizeof(struct ffa_send_direct_data) as defined by the FF-A specification 1.0
+ * in the section relevant to FFA_MSG_SEND_DIRECT_{REQ,RESP}
+ *
+ * Return:
+ *
+ * 0 on success. Otherwise, failure
+ */
+int ffa_msg_send_direct_req_hdlr(struct udevice *dev, u16 dst_part_id,
+				 struct ffa_send_direct_data *msg, bool is_smc64)
+{
+	ffa_value_t res = {0};
+	int ffa_errno;
+	u64 req_mode, resp_mode;
+	struct ffa_priv *uc_priv;
+
+	uc_priv = dev_get_uclass_priv(dev);
+
+	/* No partition installed */
+	if (!uc_priv->partitions.count || !uc_priv->partitions.descs)
+		return -ENODEV;
+
+	if (is_smc64) {
+		req_mode = FFA_SMC_64(FFA_MSG_SEND_DIRECT_REQ);
+		resp_mode = FFA_SMC_64(FFA_MSG_SEND_DIRECT_RESP);
+	} else {
+		req_mode = FFA_SMC_32(FFA_MSG_SEND_DIRECT_REQ);
+		resp_mode = FFA_SMC_32(FFA_MSG_SEND_DIRECT_RESP);
+	}
+
+	invoke_ffa_fn((ffa_value_t){
+			.a0 = req_mode,
+			.a1 = PREP_SELF_ENDPOINT_ID(uc_priv->id) |
+				PREP_PART_ENDPOINT_ID(dst_part_id),
+			.a2 = 0,
+			.a3 = msg->data0,
+			.a4 = msg->data1,
+			.a5 = msg->data2,
+			.a6 = msg->data3,
+			.a7 = msg->data4,
+			}, &res);
+
+	while (res.a0 == FFA_SMC_32(FFA_INTERRUPT))
+		invoke_ffa_fn((ffa_value_t){
+			.a0 = FFA_SMC_32(FFA_RUN),
+			.a1 = res.a1,
+			}, &res);
+
+	if (res.a0 == FFA_SMC_32(FFA_SUCCESS)) {
+		/* Message sent with no response */
+		return 0;
+	}
+
+	if (res.a0 == resp_mode) {
+		/* Message sent with response extract the return data */
+		msg->data0 = res.a3;
+		msg->data1 = res.a4;
+		msg->data2 = res.a5;
+		msg->data3 = res.a6;
+		msg->data4 = res.a7;
+
+		return 0;
+	}
+
+	ffa_errno = res.a2;
+	return ffa_to_std_errno(ffa_errno);
+}
+
+/* FF-A driver operations (used by clients for communicating with FF-A)*/
+
+/**
+ * ffa_partition_info_get() - FFA_PARTITION_INFO_GET driver operation
+ *	@uuid_str: pointer to the UUID string
+ *	@sp_count: address of the variable containing the number of partitions matching the UUID
+ *			 The variable is set by the driver
+ *	@sp_descs: address of the descriptors of the partitions matching the UUID
+ *			 The address is set by the driver
+ *
+ * Driver operation for FFA_PARTITION_INFO_GET.
+ * Please see ffa_get_partitions_info_hdlr() description for more details.
+ *
+ * Return:
+ *
+ * @sp_count: the number of partitions
+ * @sp_descs: address of the partitions descriptors
+ *
+ * On success 0 is returned. Otherwise, failure
+ */
+int ffa_partition_info_get(struct udevice *dev, const char *uuid_str,
+			   u32 *sp_count, struct ffa_partition_desc **sp_descs)
+{
+	struct ffa_bus_ops *ops = ffa_get_ops(dev);
+
+	if (!ops->partition_info_get)
+		return -ENOSYS;
+
+	return ops->partition_info_get(dev, uuid_str, sp_count, sp_descs);
+}
+
+/**
+ * ffa_sync_send_receive() - FFA_MSG_SEND_DIRECT_{REQ,RESP} driver operation
+ * @dev: The FF-A bus device
+ * @dst_part_id: destination partition ID
+ * @msg: pointer to the message data preallocated by the client (in/out)
+ * @is_smc64: select 64-bit or 32-bit FF-A ABI
+ *
+ * Driver operation for FFA_MSG_SEND_DIRECT_{REQ,RESP}.
+ * Please see ffa_msg_send_direct_req_hdlr() description for more details.
+ *
+ * Return:
+ *
+ * 0 on success. Otherwise, failure
+ */
+int ffa_sync_send_receive(struct udevice *dev, u16 dst_part_id,
+			  struct ffa_send_direct_data *msg, bool is_smc64)
+{
+	struct ffa_bus_ops *ops = ffa_get_ops(dev);
+
+	if (!ops->sync_send_receive)
+		return -ENOSYS;
+
+	return ops->sync_send_receive(dev, dst_part_id, msg, is_smc64);
+}
+
+/**
+ * ffa_rxtx_unmap() - FFA_RXTX_UNMAP driver operation
+ * @dev: The FF-A bus device
+ *
+ * Driver operation for FFA_RXTX_UNMAP.
+ * Please see ffa_unmap_rxtx_buffers_hdlr() description for more details.
+ *
+ * Return:
+ *
+ * 0 on success. Otherwise, failure
+ */
+int ffa_rxtx_unmap(struct udevice *dev)
+{
+	struct ffa_bus_ops *ops = ffa_get_ops(dev);
+
+	if (!ops->rxtx_unmap)
+		return -ENOSYS;
+
+	return ops->rxtx_unmap(dev);
+}
+
+/**
+ * ffa_do_probe() - probing FF-A framework
+ * @dev:	the FF-A bus device (arm_ffa)
+ *
+ * Probing is triggered on demand by clients searching for the uclass.
+ * At probe level the following actions are done:
+ *	- saving the FF-A framework version in uc_priv
+ *	- querying from secure world the u-boot endpoint ID
+ *	- querying from secure world the supported features of FFA_RXTX_MAP
+ *	- mapping the RX/TX buffers
+ *	- querying from secure world all the partitions information
+ *
+ * All data queried from secure world is saved in uc_priv.
+ *
+ * Return:
+ *
+ * 0 on success. Otherwise, failure
+ */
+static int ffa_do_probe(struct udevice *dev)
+{
+	int ret;
+
+	ret = ffa_get_version_hdlr(dev);
+	if (ret)
+		return ret;
+
+	ret = ffa_get_endpoint_id(dev);
+	if (ret)
+		return ret;
+
+	ret = ffa_get_rxtx_map_features_hdlr(dev);
+	if (ret)
+		return ret;
+
+	ret = ffa_map_rxtx_buffers_hdlr(dev);
+	if (ret)
+		return ret;
+
+	ret = ffa_cache_partitions_info(dev);
+	if (ret) {
+		ffa_unmap_rxtx_buffers_hdlr(dev);
+		return ret;
+	}
+
+	return 0;
+}
+
+UCLASS_DRIVER(ffa) = {
+	.name			= "ffa",
+	.id			= UCLASS_FFA,
+	.pre_probe		= ffa_do_probe,
+	.pre_remove		= ffa_unmap_rxtx_buffers_hdlr,
+	.per_device_auto	= sizeof(struct ffa_priv)
+};
diff --git a/drivers/firmware/arm-ffa/arm-ffa.c b/drivers/firmware/arm-ffa/arm-ffa.c
new file mode 100644
index 0000000..68df75b
--- /dev/null
+++ b/drivers/firmware/arm-ffa/arm-ffa.c
@@ -0,0 +1,104 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright 2022-2023 Arm Limited and/or its affiliates <open-source-office@arm.com>
+ *
+ * Authors:
+ *   Abdellatif El Khlifi <abdellatif.elkhlifi@arm.com>
+ */
+
+#include <common.h>
+#include <arm_ffa.h>
+#include <arm_ffa_priv.h>
+#include <dm.h>
+#include <log.h>
+#include <asm/global_data.h>
+#include <dm/device-internal.h>
+#include <linux/errno.h>
+
+DECLARE_GLOBAL_DATA_PTR;
+
+/**
+ * invoke_ffa_fn() - SMC wrapper
+ * @args: FF-A ABI arguments to be copied to Xn registers
+ * @res: FF-A ABI return data to be copied from Xn registers
+ *
+ * Calls low level SMC assembly function
+ */
+void invoke_ffa_fn(ffa_value_t args, ffa_value_t *res)
+{
+	arm_smccc_1_2_smc(&args, res);
+}
+
+/**
+ * arm_ffa_discover() - perform FF-A discovery
+ * @dev: The Arm FF-A bus device (arm_ffa)
+ * Try to discover the FF-A framework. Discovery is performed by
+ * querying the FF-A framework version from secure world using the FFA_VERSION ABI.
+ * Return:
+ *
+ * true on success. Otherwise, false.
+ */
+static bool arm_ffa_discover(struct udevice *dev)
+{
+	int ret;
+
+	log_info("Arm FF-A framework discovery\n");
+
+	ret = ffa_get_version_hdlr(dev);
+	if (ret)
+		return false;
+
+	return true;
+}
+
+/**
+ * arm_ffa_is_supported() - FF-A bus discovery callback
+ * @invoke_fn: legacy SMC invoke function (not used)
+ *
+ * Perform FF-A discovery by calling arm_ffa_discover().
+ * Discovery is performed by querying the FF-A framework version from
+ * secure world using the FFA_VERSION ABI.
+ *
+ * The FF-A driver is registered as an SMCCC feature driver. So, features discovery
+ * callbacks are called by the PSCI driver (PSCI device is the SMCCC features
+ * root device).
+ *
+ * The FF-A driver supports the SMCCCv1.2 extended input/output registers.
+ * So, the legacy SMC invocation is not used.
+ *
+ * Return:
+ *
+ * 0 on success. Otherwise, failure
+ */
+static bool arm_ffa_is_supported(void (*invoke_fn)(ulong a0, ulong a1,
+						   ulong a2, ulong a3,
+						   ulong a4, ulong a5,
+						   ulong a6, ulong a7,
+						   struct arm_smccc_res *res))
+{
+	return arm_ffa_discover(NULL);
+}
+
+/* Arm FF-A driver operations */
+
+static const struct ffa_bus_ops ffa_ops = {
+	.partition_info_get = ffa_get_partitions_info_hdlr,
+	.sync_send_receive = ffa_msg_send_direct_req_hdlr,
+	.rxtx_unmap = ffa_unmap_rxtx_buffers_hdlr,
+};
+
+/* Registering the FF-A driver as an SMCCC feature driver */
+
+ARM_SMCCC_FEATURE_DRIVER(arm_ffa) = {
+	.driver_name = FFA_DRV_NAME,
+	.is_supported = arm_ffa_is_supported,
+};
+
+/* Declaring the FF-A driver under UCLASS_FFA */
+
+U_BOOT_DRIVER(arm_ffa) = {
+	.name		= FFA_DRV_NAME,
+	.id		= UCLASS_FFA,
+	.flags		= DM_REMOVE_OS_PREPARE,
+	.ops		= &ffa_ops,
+};
diff --git a/drivers/firmware/arm-ffa/sandbox_arm_ffa_priv.h b/drivers/firmware/arm-ffa/sandbox_arm_ffa_priv.h
new file mode 100644
index 0000000..4338f9c
--- /dev/null
+++ b/drivers/firmware/arm-ffa/sandbox_arm_ffa_priv.h
@@ -0,0 +1,14 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * Copyright 2022-2023 Arm Limited and/or its affiliates <open-source-office@arm.com>
+ *
+ * Authors:
+ *   Abdellatif El Khlifi <abdellatif.elkhlifi@arm.com>
+ */
+
+#ifndef __SANDBOX_ARM_FFA_PRV_H
+#define __SANDBOX_ARM_FFA_PRV_H
+
+/* Future sandbox support private declarations */
+
+#endif