1* Power State Coordination Interface (PSCI) 2 3Firmware implementing the PSCI functions described in ARM document number 4ARM DEN 0022A ("Power State Coordination Interface System Software on ARM 5processors") can be used by Linux to initiate various CPU-centric power 6operations. 7 8Issue A of the specification describes functions for CPU suspend, hotplug 9and migration of secure software. 10 11Functions are invoked by trapping to the privilege level of the PSCI 12firmware (specified as part of the binding below) and passing arguments 13in a manner similar to that specified by AAPCS: 14 15 r0 => 32-bit Function ID / return value 16 {r1 - r3} => Parameters 17 18Note that the immediate field of the trapping instruction must be set 19to #0. 20 21 22Main node required properties: 23 24 - compatible : Must be "arm,psci" 25 26 - method : The method of calling the PSCI firmware. Permitted 27 values are: 28 29 "smc" : SMC #0, with the register assignments specified 30 in this binding. 31 32 "hvc" : HVC #0, with the register assignments specified 33 in this binding. 34 35Main node optional properties: 36 37 - cpu_suspend : Function ID for CPU_SUSPEND operation 38 39 - cpu_off : Function ID for CPU_OFF operation 40 41 - cpu_on : Function ID for CPU_ON operation 42 43 - migrate : Function ID for MIGRATE operation 44 45 46Example: 47 48 psci { 49 compatible = "arm,psci"; 50 method = "smc"; 51 cpu_suspend = <0x95c10000>; 52 cpu_off = <0x95c10001>; 53 cpu_on = <0x95c10002>; 54 migrate = <0x95c10003>; 55 }; 56