0d06b058a5
TX FIFO has space for 32 characters. With default UART baudrate 115200 it takes more than 2ms to transmit all 32 characters, so wait at least 3ms before flushing TX FIFO. If WTMI firmware transmitted something via UART before TF-A was booted, some characters may still wait in TX FIFO when TF-A is initializing UART driver. So wait at least 3ms to ensure that HW has enough time to transmit all characters waiting in TX FIFO. This fixes an issue where sometimes characters transmitted on UART by our custom WTMI image are lost. Signed-off-by: Pali Rohár <pali@kernel.org> Change-Id: I8ea4ea58e4ba3e0c0d7f47e679171b9b94442f19 |
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readme.rst
Trusted Firmware-A
Trusted Firmware-A (TF-A) is a reference implementation of secure world software for Arm A-Profile architectures (Armv8-A and Armv7-A), including an Exception Level 3 (EL3) Secure Monitor. It provides a suitable starting point for productization of secure world boot and runtime firmware, in either the AArch32 or AArch64 execution states.
TF-A implements Arm interface standards, including:
- Power State Coordination Interface (PSCI)
- Trusted Board Boot Requirements CLIENT (TBBR-CLIENT)
- SMC Calling Convention
- System Control and Management Interface (SCMI)
- Software Delegated Exception Interface (SDEI)
The code is designed to be portable and reusable across hardware platforms and software models that are based on the Armv8-A and Armv7-A architectures.
In collaboration with interested parties, we will continue to enhance TF-A with reference implementations of Arm standards to benefit developers working with Armv7-A and Armv8-A TrustZone technology.
Users are encouraged to do their own security validation, including penetration testing, on any secure world code derived from TF-A.
More Info and Documentation
To find out more about Trusted Firmware-A, please view the full documentation that is available through trustedfirmware.org.
Copyright (c) 2013-2019, Arm Limited and Contributors. All rights reserved.