Power Management for the Devices - 2020.2 English

Clock Gating

Stop device clocks when they are not being used (also called Common Clock Framework.) The kernel configurations required are:

• Common Clock Framework
  • [*] Support for Xilinx ZynqMP Ultrascale+ clock controllers

Runtime PM

Power off devices when they are not being used. Note that individual drivers may or may not support run-time power management. The kernel configurations required are:

• Power management options
  • [*] Suspend to RAM and standby
• Device Drivers
  • SoC (System-on-a-chip) specific drivers
    • [*] Xilinx Zynq MPSoC driver support

Global General Storage Registers

Four 32-bit storage registers are available for general use. Their values are not preserved across after software reboots. The following table lists the global general storage registers.

Read the value of a global storage register:

$cat /sys/firmware/zynqmp/ggs0

Write the mask and value of a global storage register:

$echo 0xFFFFFFFF 0x1234ABCD > /sys/firmware/zynqmp/ggs0

Persistent Global General Storage Registers

Four 32-bit persistent global storage registers are available for general use. Their values are preserved across after software reboots. The lists the persistent global general storage registers.

Read the value of a persistent global storage register:

$cat /sys/firmware/zynqmp/pggs0

Write the mask and value of a persistent global storage register:

$echo 0xFFFFFFFF 0x1234ABCD > /sys/firmware/zynqmp/pggs0