1# SPDX-License-Identifier: GPL-2.0 2 3config ARM_FFA_TRANSPORT 4 bool "Enable Arm Firmware Framework for Armv8-A driver" 5 depends on DM && (ARM64 || SANDBOX) 6 select ARM_SMCCC if !SANDBOX 7 select ARM_SMCCC_FEATURES if !SANDBOX 8 imply CMD_ARMFFA 9 select LIB_UUID 10 select DEVRES 11 help 12 The Firmware Framework for Arm A-profile processors (FF-A) 13 describes interfaces (ABIs) that standardize communication 14 between the Secure World and Normal World leveraging TrustZone 15 technology. 16 17 The FF-A support in U-Boot is based on FF-A specification v1.0 and uses SMC32 18 calling convention. 19 20 FF-A specification: 21 22 https://developer.arm.com/documentation/den0077/a/?lang=en 23 24 In U-Boot FF-A design, FF-A is considered as a discoverable bus. 25 FF-A bus is discovered using ARM_SMCCC_FEATURES mechanism performed 26 by the PSCI driver. 27 The Secure World is considered as one entity to communicate with 28 using the FF-A bus. 29 FF-A communication is handled by one device and one instance (the bus). 30 The FF-A support on U-Boot takes care of all the interactions between Normal 31 world and Secure World. 32 33 Generic FF-A methods are implemented in the Uclass (arm-ffa-uclass.c). 34 Arm specific methods are implemented in the Arm driver (arm-ffa.c). 35 36 FF-A sandbox is provided to run FF-A under sandbox and allows to test the FF-A Uclass. 37 Sandbox support includes an emulator for Arm FF-A which emulates the FF-A side of 38 the Secure World and provides FF-A ABIs inspection methods (ffa-emul-uclass.c). 39 An FF-A sandbox driver is also provided for FF-A communication with the emulated 40 Secure World (sandbox_ffa.c). 41 42 For more details about the FF-A support, please refer to doc/arch/arm64.ffa.rst 43