| * Power State Coordination Interface (PSCI) |
| |
| Firmware implementing the PSCI functions described in ARM document number |
| ARM DEN 0022A ("Power State Coordination Interface System Software on ARM |
| processors") can be used by Linux to initiate various CPU-centric power |
| operations. |
| |
| Issue A of the specification describes functions for CPU suspend, hotplug |
| and migration of secure software. |
| |
| Functions are invoked by trapping to the privilege level of the PSCI |
| firmware (specified as part of the binding below) and passing arguments |
| in a manner similar to that specified by AAPCS: |
| |
| r0 => 32-bit Function ID / return value |
| {r1 - r3} => Parameters |
| |
| Note that the immediate field of the trapping instruction must be set |
| to #0. |
| |
| |
| Main node required properties: |
| |
| - compatible : Must be "arm,psci" |
| |
| - method : The method of calling the PSCI firmware. Permitted |
| values are: |
| |
| "smc" : SMC #0, with the register assignments specified |
| in this binding. |
| |
| "hvc" : HVC #0, with the register assignments specified |
| in this binding. |
| |
| Main node optional properties: |
| |
| - cpu_suspend : Function ID for CPU_SUSPEND operation |
| |
| - cpu_off : Function ID for CPU_OFF operation |
| |
| - cpu_on : Function ID for CPU_ON operation |
| |
| - migrate : Function ID for MIGRATE operation |
| |
| |
| Example: |
| |
| psci { |
| compatible = "arm,psci"; |
| method = "smc"; |
| cpu_suspend = <0x95c10000>; |
| cpu_off = <0x95c10001>; |
| cpu_on = <0x95c10002>; |
| migrate = <0x95c10003>; |
| }; |