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>

1 files changed, 104 insertions, 0 deletions

diff --git a/drivers/firmware/arm-ffa/arm-ffa.c b/drivers/firmware/arm-ffa/arm-ffa.c
new file mode 100644
index 00000000000..68df75bd9e5
--- /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,
+};