mirror of
https://github.com/CTCaer/switch-l4t-atf.git
synced 2024-12-04 08:53:37 +00:00
6f62574767
Due to recent issues in the rendering of the documentation on GitHub and some long-standing issues like the lack of automatic table of content in Markdown, the documentation has been converted to reStructuredText. Basic constructs looks pretty similar to Markdown. Automatically convert GitHub markdown documentation to reStructuredText using pandoc. Change-Id: If20b695acedc6d1b49c8d9fb64efd6b6ba23f4a9 Signed-off-by: Douglas Raillard <douglas.raillard@arm.com>
97 lines
3.8 KiB
ReStructuredText
97 lines
3.8 KiB
ReStructuredText
ARM SiP Service
|
|
===============
|
|
|
|
This document enumerates and describes the ARM SiP (Silicon Provider) services.
|
|
|
|
SiP services are non-standard, platform-specific services offered by the silicon
|
|
implementer or platform provider. They are accessed via. ``SMC`` ("SMC calls")
|
|
instruction executed from Exception Levels below EL3. SMC calls for SiP
|
|
services:
|
|
|
|
- Follow `SMC Calling Convention`_;
|
|
- Use SMC function IDs that fall in the SiP range, which are ``0xc2000000`` -
|
|
``0xc200ffff`` for 64-bit calls, and ``0x82000000`` - ``0x8200ffff`` for 32-bit
|
|
calls.
|
|
|
|
The ARM SiP implementation offers the following services:
|
|
|
|
- Performance Measurement Framework (PMF)
|
|
- Execution State Switching service
|
|
|
|
Source definitions for ARM SiP service are located in the ``arm_sip_svc.h`` header
|
|
file.
|
|
|
|
Performance Measurement Framework (PMF)
|
|
---------------------------------------
|
|
|
|
The `Performance Measurement Framework`_
|
|
allows callers to retrieve timestamps captured at various paths in ARM Trusted
|
|
Firmware execution. It's described in detail in `Firmware Design document`_.
|
|
|
|
Execution State Switching service
|
|
---------------------------------
|
|
|
|
Execution State Switching service provides a mechanism for a non-secure lower
|
|
Exception Level (either EL2, or NS EL1 if EL2 isn't implemented) to request to
|
|
switch its execution state (a.k.a. Register Width), either from AArch64 to
|
|
AArch32, or from AArch32 to AArch64, for the calling CPU. This service is only
|
|
available when ARM Trusted Firmware is built for AArch64 (i.e. when build option
|
|
``ARCH`` is set to ``aarch64``).
|
|
|
|
``ARM_SIP_SVC_EXE_STATE_SWITCH``
|
|
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
|
|
|
|
::
|
|
|
|
Arguments:
|
|
uint32_t Function ID
|
|
uint32_t PC hi
|
|
uint32_t PC lo
|
|
uint32_t Cookie hi
|
|
uint32_t Cookie lo
|
|
|
|
Return:
|
|
uint32_t
|
|
|
|
The function ID parameter must be ``0x82000020``. It uniquely identifies the
|
|
Execution State Switching service being requested.
|
|
|
|
The parameters *PC hi* and *PC lo* defines upper and lower words, respectively,
|
|
of the entry point (physical address) at which execution should start, after
|
|
Execution State has been switched. When calling from AArch64, *PC hi* must be 0.
|
|
|
|
When execution starts at the supplied entry point after Execution State has been
|
|
switched, the parameters *Cookie hi* and *Cookie lo* are passed in CPU registers
|
|
0 and 1, respectively. When calling from AArch64, *Cookie hi* must be 0.
|
|
|
|
This call can only be made on the primary CPU, before any secondaries were
|
|
brought up with ``CPU_ON`` PSCI call. Otherwise, the call will always fail.
|
|
|
|
The effect of switching execution state is as if the Exception Level were
|
|
entered for the first time, following power on. This means CPU registers that
|
|
have a defined reset value by the Architecture will assume that value. Other
|
|
registers should not be expected to hold their values before the call was made.
|
|
CPU endianness, however, is preserved from the previous execution state. Note
|
|
that this switches the execution state of the calling CPU only. This is not a
|
|
substitute for PSCI ``SYSTEM_RESET``.
|
|
|
|
The service may return the following error codes:
|
|
|
|
- ``STATE_SW_E_PARAM``: If any of the parameters were deemed invalid for
|
|
a specific request.
|
|
- ``STATE_SW_E_DENIED``: If the call is not successful, or when ARM Trusted
|
|
Firmware is built for AArch32.
|
|
|
|
If the call is successful, the caller wouldn't observe the SMC returning.
|
|
Instead, execution starts at the supplied entry point, with the CPU registers 0
|
|
and 1 populated with the supplied *Cookie hi* and *Cookie lo* values,
|
|
respectively.
|
|
|
|
--------------
|
|
|
|
*Copyright (c) 2017, ARM Limited and Contributors. All rights reserved.*
|
|
|
|
.. _SMC Calling Convention: http://infocenter.arm.com/help/topic/com.arm.doc.den0028a/index.html
|
|
.. _Performance Measurement Framework: ./firmware-design.rst#user-content-performance-measurement-framework
|
|
.. _Firmware Design document: ./firmware-design.rst
|