-----Original Message----- From: TF-A tf-a-bounces@lists.trustedfirmware.org On Behalf Of Gutierrez, Hernan Ildefonso (Boise R&D, FW) via TF-A Sent: 24 June 2019 22:35 To: tf-a@lists.trustedfirmware.org Subject: [TF-A] Armv8A Suspend/Resume reference code

Hi,

I am looking for reference code for ArmV8A core suspend/resume. Are there code references that are suggested to look for? Application notes to read?

Hi Hernan, The PSCI Spec[1] specifies power management on ARM CPUs and this includes suspend and resume. The TF-A provides an implementation of PSCI with appropriate hooks to plug-in in platform specifics. There are documents in the `docs` folder which cover different aspects of PSCI implementation like PSCI topology [2], CPU specifics [3], and platform porting guide [4].

In terms of adding support for a new platform, it is most likely that all the architectural (as in ARMv8A reference manual) and the CPU specific power management as specified in the TRM are covered already (see lib/cpus/ folder for CPUs already supported). So it’s a matter of implementing the platform hooks as mentioned in the porting guide [4].

With respect to implementing platform hooks, the ARM reference platforms like FVP provide an example of how the hooks can be implemented (see fvp_pm.c/fvp_topology.c ). So if you platform is a GICv3 system and the power controller already uses SCMI as the protocol for communication, then most of the code in FVP can be reused for your platform.

Hope that provides a starting point for you to begin.

[1] http://infocenter.arm.com/help/topic/com.arm.doc.den0022d/Power_State_Coordi... [2] https://git.trustedfirmware.org/TF-A/trusted-firmware-a.git/about/docs/desig... [3] https://git.trustedfirmware.org/TF-A/trusted-firmware-a.git/about/docs/desig... (see CPU specific operations framework) [4] https://git.trustedfirmware.org/TF-A/trusted-firmware-a.git/about/docs/getti... (see Power State Coordination Interface)

Any pointers will be appreciated, thanks.

Hernan

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