* Low Power Management Levels

The application processor in MSM can do a variety of C-States for low power
management. The LPM module performs the System low power modes based on
the latency/residency information of the individual CPUs and clusters.

LPM-levels defines a hierarchy of low power modes that a cluster and
clusters/cpus within that cluster can enter. The bottom hierarchy level
represents the low power modes that a CPU can enter. The CPU low power nodes
are associated with a cluster that defines the low power modes that a cluster
can enter. For system involving a hierarchy of clusters, the cluster low power
modes can be contained within another cluster.

[Top Level Node]
Required properties:

- compatible: "qcom,lpm-levels"

[Node bindings for qcom,pm-cluster]
 Required properties:
	- reg - The numeric cluster id
	- label: Identifies the cluster name. The name will be
	used when reporting the stats for each low power mode.
	- qcom,spm-device-names: List of  SPM device names which control the
	low power modes for this driver. The lpm driver uses the device name
	to obtain a handle to the SPM driver that controls the cluster's low
	power mode. This is only required if "qcom,use-psci" is not defined.
	- qcom,default-level: The default low power level that a cluster is
	programmed. The SPM of the corresponding device is configured at this
	low power mode by default.
	- qcom,cpu: List of CPU phandles to identify the CPUs associated with
	this cluster. This property is required if and only if the cluster
	node contains a qcom,pm-cpu node.

	qcom,pm-cluster contains qcom,pm-cluster-level nodes which identify
	the various low power modes that the cluster can enter. The
	qcom,pm-cluster node should also include another cluster node or a cpu
	node that defines their respective low power modes.

[Node bindings for qcom,pm-cluster-level]
 Required properties:
	- reg: The numeric cluster level id
	- label: Name to identify the low power mode in stats
	module.
	- qcom,spm-<device-name>-mode: For each SPM device defined in
	qcom,spm-devices-names, a corresponding entry identifying the low
	power mode is expected. For example, the qcom,pm-cluster node contains
	a SPM device by name "l2" then the cluster level should contain a
	qcom,spm-l2-mode.  When a cluster level is chosen ,the SPM device is
	programmed with its
	corresponding low power mode. The accepted values for this property
	are:
		- "active"
		- "wfi"
		- "retention"
		- "gdhs"
		- "pc"
		- "fpc"
	- qcom,min-child-idx: The minimum level that a child CPU should be in
	before this level can be chosen. This property is required for all
        non-default level.
	- qcom,latency-us: The latency in handling the interrupt if this level
	was chosen, in uSec
	- qcom,ss-power: The steady state power expelled when the processor is
	in this level in mWatts
	- qcom,energy-overhead: The energy used up in entering and exiting
	this level in mWatts.uSec
	- qcom,time-overhead: The time spent in entering and exiting this
	level in uS
 Optional properties:
	- qcom,notify-rpm: When set, the driver flushes the RPM sleep set and
	configures the virtual MPM driver in prepration for a RPM assisted
	sleep.
	- qcom,last-level - When set, the cluster level is applied only when
	there is 1 online core.
	- qcom,disable-dynamic-int-routing: When set disables the dynamic
	routing of rpm-smd and mpm interrupts to next wake up core.
	- qcom,use-psci: This boolean property allows the LPM modules to
	terminate in PSCI to configure SPM for low power modes.
	- qcom,psci-mode-shift: The property is used to determine with bit
	location of the cluster mode in the composite state ID used to define
	cluster low power modes in PSCI v1.0. Required only if qcom,use-psci
	is defined at the lpm-levels root node.
	- qcom,psci-mode-mask: The property is used to determine with bit
	mask of the cluster mode in the composite state ID used to define
	cluster low power modes in PSCI v1.0. Required only if qcom,use-psci
	is defined at the lpm-levels root node.
	- qcom,psci-mode: ID to be passed into the PSCI firmware. Required
	only if qcom,use-psci is defined at the lpm-levels root node.
	- qcom,is-reset: This boolean property will tell whether
	cluster level need power management notifications to be sent out
	or not for the drivers to prepare for cluster collapse.

[Node bindings for qcom,pm-cpu]
qcom,pm-cpu contains the low power modes that a cpu could enter. Currently it
doesn't have any required properties and is a container for
qcom,pm-cpu-levels.

[Node bindings for qcom,pm-cpu-levels]
 Required properties:
	- reg: The numeric cpu level id
	- qcom,spm-cpu-mode: The sleep mode of the processor, values for the
	property are:
		"wfi" - Wait for Interrupt
		"retention" - Retention
		"standalone_pc" - Standalone power collapse
		"pc" - Power Collapse
	- qcom,latency-us: The latency in handling the interrupt if this level
	was chosen, in uSec
	- qcom,ss-power: The steady state power expelled when the processor is
	in this level in mWatts
	- qcom,energy-overhead: The energy used up in entering and exiting
	this level in mWatts.uSec
	- qcom,time-overhead: The time spent in entering and exiting this
	level in uS
	- qcom,use-broadcast-timer: Indicates that the timer gets reset during
	power collapse and the cpu relies on Broadcast timer for scheduled
	wakeups. Required only for states where the CPUs internal timer state
	is lost.

 Optional properties:
	- qcom,psci-mode-shift: Same as cluster level fields.
	- qcom,psci-mode-mask: Same as cluster level fields.
	- qcom,psci-cpu-mode: ID to be passed into PSCI firmware.
	- qcom,jtag-save-restore: A boolean specifying jtag registers save and restore
	required are not.
	- qcom,is-reset: This boolean property maps to "power state" bit in PSCI
	state_id configuration. This property will tell whether CPU get reset for
	a particular LPM or not. This property will also be used to notify the
	drivers in case of cpu reset.

[Example dts]

qcom,lpm-levels {
	#address-cells = <1>;
	#size-cells = <0>;
	compatible = "qcom,lpm-levels";

	qcom,pm-cluster@0 {
		#address-cells = <1>;
		#size-cells = <0>;
		reg = <0>;
		label = "system";
		qcom,spm-device-names = "cci";
		qcom,default-level = <0>;

		qcom,pm-cluster-level@0{
			reg = <0>;
			label = "system-cci-retention";
			qcom,spm-cci-mode = "retention";
			qcom,latency-us = <100>;
			qcom,ss-power = <1000>;
			qcom,energy-overhead = <300000>;
			qcom,time-overhead = <100>;
		};

		qcom,pm-cluster-level@2{
			reg = <1>;
			label = "system-cci-pc";
			qcom,spm-cci-mode = "pc";
			qcom,latency-us = <30000>;
			qcom,ss-power = <83>;
			qcom,energy-overhead = <2274420>;
			qcom,time-overhead = <6605>;
			qcom,min-child-idx = <1>;
			qcom,notify-rpm;
		};

		qcom,pm-cluster@0{
			#address-cells = <1>;
			#size-cells = <0>;
			reg = <0>;
			label = "a53";
			qcom,spm-device-names = "l2";
			qcom,default-level=<0>;
			qcom,cpu = <&CPU0 &CPU1 &CPU2 &CPU3>;

			qcom,pm-cluster-level@0{
				reg = <0>;
				label = "a53-l2-retention";
				qcom,spm-l2-mode = "retention";
				qcom,latency-us = <100>;
				qcom,ss-power = <1000>;
				qcom,energy-overhead = <300000>;
				qcom,time-overhead = <100>;
			};

			qcom,pm-cluster-level@1{
				reg = <1>;
				label = "a53-l2-pc";
				qcom,spm-l2-mode = "pc";
				qcom,latency-us = <30000>;
				qcom,ss-power = <83>;
				qcom,energy-overhead = <2274420>;
				qcom,time-overhead = <6605>;
				qcom,min-child-idx = <3>;
			};

			qcom,pm-cpu {
				#address-cells = <1>;
				#size-cells = <0>;
				qcom,pm-cpu-level@0 {
					reg = <0>;
					qcom,spm-cpu-mode = "wfi";
					qcom,latency-us = <1>;
					qcom,ss-power = <715>;
					qcom,energy-overhead = <17700>;
					qcom,time-overhead = <2>;
				};

				qcom,pm-cpu-level@1 {
					reg = <1>;
					qcom,spm-cpu-mode = "retention";
					qcom,latency-us = <35>;
					qcom,ss-power = <542>;
					qcom,energy-overhead = <34920>;
					qcom,time-overhead = <40>;
				};

				qcom,pm-cpu-level@2 {
					reg = <2>;
					qcom,spm-cpu-mode = "standalone_pc";
					qcom,latency-us = <300>;
					qcom,ss-power = <476>;
					qcom,energy-overhead = <225300>;
					qcom,time-overhead = <350>;
				};

				qcom,pm-cpu-level@3 {
					reg = <3>;
					qcom,spm-cpu-mode = "pc";
					qcom,latency-us = <500>;
					qcom,ss-power = <163>;
					qcom,energy-overhead = <577736>;
					qcom,time-overhead = <1000>;
				};
			};
		};

		qcom,pm-cluster@1{
			#address-cells = <1>;
			#size-cells = <0>;
			reg = <1>;
			label = "a57";
			qcom,spm-device-names = "l2";
			qcom,default-level=<0>;
			qcom,cpu = <&CPU4 &CPU5 &CPU6 &CPU7>;

			qcom,pm-cluster-level@0{
				reg = <0>;
				label = "a57-l2-retention";
				qcom,spm-l2-mode = "retention";
				qcom,latency-us = <100>;
				qcom,ss-power = <1000>;
				qcom,energy-overhead = <300000>;
				qcom,time-overhead = <100>;
			};

			qcom,pm-cluster-level@2{
				reg = <1>;
				label = "a57-l2-pc";
				qcom,spm-l2-mode = "pc";
				qcom,latency-us = <30000>;
				qcom,ss-power = <83>;
				qcom,energy-overhead = <2274420>;
				qcom,time-overhead = <6605>;
				qcom,min-child-idx = <3>;
			};

			qcom,pm-cpu {
				#address-cells = <1>;
				#size-cells = <0>;
				qcom,pm-cpu-level@0 {
					reg = <0>;
					qcom,spm-cpu-mode = "wfi";
					qcom,latency-us = <1>;
					qcom,ss-power = <715>;
					qcom,energy-overhead = <17700>;
					qcom,time-overhead = <2>;
				};

				qcom,pm-cpu-level@1 {
					reg = <1>;
					qcom,spm-cpu-mode = "retention";
					qcom,latency-us = <35>;
					qcom,ss-power = <542>;
					qcom,energy-overhead = <34920>;
					qcom,time-overhead = <40>;
				};

				qcom,pm-cpu-level@2 {
					reg = <2>;
					qcom,spm-cpu-mode = "standalone_pc";
					qcom,latency-us = <300>;
					qcom,ss-power = <476>;
					qcom,energy-overhead = <225300>;
					qcom,time-overhead = <350>;
				};

				qcom,pm-cpu-level@3 {
					reg = <3>;
					qcom,spm-cpu-mode = "pc";
					qcom,latency-us = <500>;
					qcom,ss-power = <163>;
					qcom,energy-overhead = <577736>;
					qcom,time-overhead = <1000>;
				};
			};
		};
	};


};