Documentation/devicetree/bindings/power/power_domain.txt - pub/scm/linux/kernel/git/kbingham/rcar - Git at Google

 * Generic PM domains

 System on chip designs are often divided into multiple PM domains that can be
 used for power gating of selected IP blocks for power saving by reduced leakage
 current.

 This device tree binding can be used to bind PM domain consumer devices with
 their PM domains provided by PM domain providers. A PM domain provider can be
 represented by any node in the device tree and can provide one or more PM
 domains. A consumer node can refer to the provider by a phandle and a set of
 phandle arguments (so called PM domain specifiers) of length specified by the
 #power-domain-cells property in the PM domain provider node.

 ==PM domain providers==

 Required properties:
  - #power-domain-cells : Number of cells in a PM domain specifier;
    Typically 0 for nodes representing a single PM domain and 1 for nodes
    providing multiple PM domains (e.g. power controllers), but can be any value
    as specified by device tree binding documentation of particular provider.

 Optional properties:
  - power-domains : A phandle and PM domain specifier as defined by bindings of
                    the power controller specified by phandle.
    Some power domains might be powered from another power domain (or have
    other hardware specific dependencies). For representing such dependency
    a standard PM domain consumer binding is used. When provided, all domains
    created by the given provider should be subdomains of the domain
    specified by this binding. More details about power domain specifier are
    available in the next section.

 - domain-idle-states : A phandle of an idle-state that shall be soaked into a
                 generic domain power state. The idle state definitions are
                 compatible with domain-idle-state specified in [1]. phandles
                 that are not compatible with domain-idle-state will be
                 ignored.
   The domain-idle-state property reflects the idle state of this PM domain and
   not the idle states of the devices or sub-domains in the PM domain. Devices
   and sub-domains have their own idle-states independent of the parent
   domain's idle states. In the absence of this property, the domain would be
   considered as capable of being powered-on or powered-off.

 - operating-points-v2 : Phandles to the OPP tables of power domains provided by
   a power domain provider. If the provider provides a single power domain only
   or all the power domains provided by the provider have identical OPP tables,
   then this shall contain a single phandle. Refer to ../opp/opp.txt for more
   information.

 Example:

 	power: power-controller@12340000 {
 		compatible = "foo,power-controller";
 		reg = <0x12340000 0x1000>;
 		#power-domain-cells = <1>;
 	};

 The node above defines a power controller that is a PM domain provider and
 expects one cell as its phandle argument.

 Example 2:

 	parent: power-controller@12340000 {
 		compatible = "foo,power-controller";
 		reg = <0x12340000 0x1000>;
 		#power-domain-cells = <1>;
 	};

 	child: power-controller@12341000 {
 		compatible = "foo,power-controller";
 		reg = <0x12341000 0x1000>;
 		power-domains = <&parent 0>;
 		#power-domain-cells = <1>;
 	};

 The nodes above define two power controllers: 'parent' and 'child'.
 Domains created by the 'child' power controller are subdomains of '0' power
 domain provided by the 'parent' power controller.

 Example 3:
 	parent: power-controller@12340000 {
 		compatible = "foo,power-controller";
 		reg = <0x12340000 0x1000>;
 		#power-domain-cells = <0>;
 		domain-idle-states = <&DOMAIN_RET>, <&DOMAIN_PWR_DN>;
 	};

 	child: power-controller@12341000 {
 		compatible = "foo,power-controller";
 		reg = <0x12341000 0x1000>;
 		power-domains = <&parent>;
 		#power-domain-cells = <0>;
 		domain-idle-states = <&DOMAIN_PWR_DN>;
 	};

 	DOMAIN_RET: state@0 {
 		compatible = "domain-idle-state";
 		reg = <0x0>;
 		entry-latency-us = <1000>;
 		exit-latency-us = <2000>;
 		min-residency-us = <10000>;
 	};

 	DOMAIN_PWR_DN: state@1 {
 		compatible = "domain-idle-state";
 		reg = <0x1>;
 		entry-latency-us = <5000>;
 		exit-latency-us = <8000>;
 		min-residency-us = <7000>;
 	};

 ==PM domain consumers==

 Required properties:
  - power-domains : A phandle and PM domain specifier as defined by bindings of
                    the power controller specified by phandle.

 Example:

 	leaky-device@12350000 {
 		compatible = "foo,i-leak-current";
 		reg = <0x12350000 0x1000>;
 		power-domains = <&power 0>;
 	};

 The node above defines a typical PM domain consumer device, which is located
 inside a PM domain with index 0 of a power controller represented by a node
 with the label "power".

 Optional properties:
 - required-opps: This contains phandle to an OPP node in another device's OPP
   table. It may contain an array of phandles, where each phandle points to an
   OPP of a different device. It should not contain multiple phandles to the OPP
   nodes in the same OPP table. This specifies the minimum required OPP of the
   device(s), whose OPP's phandle is present in this property, for the
   functioning of the current device at the current OPP (where this property is
   present).

 Example:
 - OPP table for domain provider that provides two domains.

 	domain0_opp_table: opp-table0 {
 		compatible = "operating-points-v2";

 		domain0_opp_0: opp-1000000000 {
 			opp-hz = /bits/ 64 <1000000000>;
 			opp-microvolt = <975000 970000 985000>;
 		};
 		domain0_opp_1: opp-1100000000 {
 			opp-hz = /bits/ 64 <1100000000>;
 			opp-microvolt = <1000000 980000 1010000>;
 		};
 	};

 	domain1_opp_table: opp-table1 {
 		compatible = "operating-points-v2";

 		domain1_opp_0: opp-1200000000 {
 			opp-hz = /bits/ 64 <1200000000>;
 			opp-microvolt = <975000 970000 985000>;
 		};
 		domain1_opp_1: opp-1300000000 {
 			opp-hz = /bits/ 64 <1300000000>;
 			opp-microvolt = <1000000 980000 1010000>;
 		};
 	};

 	power: power-controller@12340000 {
 		compatible = "foo,power-controller";
 		reg = <0x12340000 0x1000>;
 		#power-domain-cells = <1>;
 		operating-points-v2 = <&domain0_opp_table>, <&domain1_opp_table>;
 	};

 	leaky-device0@12350000 {
 		compatible = "foo,i-leak-current";
 		reg = <0x12350000 0x1000>;
 		power-domains = <&power 0>;
 		required-opps = <&domain0_opp_0>;
 	};

 	leaky-device1@12350000 {
 		compatible = "foo,i-leak-current";
 		reg = <0x12350000 0x1000>;
 		power-domains = <&power 1>;
 		required-opps = <&domain1_opp_1>;
 	};

 [1]. Documentation/devicetree/bindings/power/domain-idle-state.txt
	* Generic PM domains

	System on chip designs are often divided into multiple PM domains that can be
	used for power gating of selected IP blocks for power saving by reduced leakage
	current.

	This device tree binding can be used to bind PM domain consumer devices with
	their PM domains provided by PM domain providers. A PM domain provider can be
	represented by any node in the device tree and can provide one or more PM
	domains. A consumer node can refer to the provider by a phandle and a set of
	phandle arguments (so called PM domain specifiers) of length specified by the
	#power-domain-cells property in the PM domain provider node.

	==PM domain providers==

	Required properties:
	- #power-domain-cells : Number of cells in a PM domain specifier;
	Typically 0 for nodes representing a single PM domain and 1 for nodes
	providing multiple PM domains (e.g. power controllers), but can be any value
	as specified by device tree binding documentation of particular provider.

	Optional properties:
	- power-domains : A phandle and PM domain specifier as defined by bindings of
	the power controller specified by phandle.
	Some power domains might be powered from another power domain (or have
	other hardware specific dependencies). For representing such dependency
	a standard PM domain consumer binding is used. When provided, all domains
	created by the given provider should be subdomains of the domain
	specified by this binding. More details about power domain specifier are
	available in the next section.

	- domain-idle-states : A phandle of an idle-state that shall be soaked into a
	generic domain power state. The idle state definitions are
	compatible with domain-idle-state specified in [1]. phandles
	that are not compatible with domain-idle-state will be
	ignored.
	The domain-idle-state property reflects the idle state of this PM domain and
	not the idle states of the devices or sub-domains in the PM domain. Devices
	and sub-domains have their own idle-states independent of the parent
	domain's idle states. In the absence of this property, the domain would be
	considered as capable of being powered-on or powered-off.

	- operating-points-v2 : Phandles to the OPP tables of power domains provided by
	a power domain provider. If the provider provides a single power domain only
	or all the power domains provided by the provider have identical OPP tables,
	then this shall contain a single phandle. Refer to ../opp/opp.txt for more
	information.

	Example:

	power: power-controller@12340000 {
	compatible = "foo,power-controller";
	reg = <0x12340000 0x1000>;
	#power-domain-cells = <1>;
	};

	The node above defines a power controller that is a PM domain provider and
	expects one cell as its phandle argument.

	Example 2:

	parent: power-controller@12340000 {
	compatible = "foo,power-controller";
	reg = <0x12340000 0x1000>;
	#power-domain-cells = <1>;
	};

	child: power-controller@12341000 {
	compatible = "foo,power-controller";
	reg = <0x12341000 0x1000>;
	power-domains = <&parent 0>;
	#power-domain-cells = <1>;
	};

	The nodes above define two power controllers: 'parent' and 'child'.
	Domains created by the 'child' power controller are subdomains of '0' power
	domain provided by the 'parent' power controller.

	Example 3:
	parent: power-controller@12340000 {
	compatible = "foo,power-controller";
	reg = <0x12340000 0x1000>;
	#power-domain-cells = <0>;
	domain-idle-states = <&DOMAIN_RET>, <&DOMAIN_PWR_DN>;
	};

	child: power-controller@12341000 {
	compatible = "foo,power-controller";
	reg = <0x12341000 0x1000>;
	power-domains = <&parent>;
	#power-domain-cells = <0>;
	domain-idle-states = <&DOMAIN_PWR_DN>;
	};

	DOMAIN_RET: state@0 {
	compatible = "domain-idle-state";
	reg = <0x0>;
	entry-latency-us = <1000>;
	exit-latency-us = <2000>;
	min-residency-us = <10000>;
	};

	DOMAIN_PWR_DN: state@1 {
	compatible = "domain-idle-state";
	reg = <0x1>;
	entry-latency-us = <5000>;
	exit-latency-us = <8000>;
	min-residency-us = <7000>;
	};

	==PM domain consumers==

	Required properties:
	- power-domains : A phandle and PM domain specifier as defined by bindings of
	the power controller specified by phandle.

	Example:

	leaky-device@12350000 {
	compatible = "foo,i-leak-current";
	reg = <0x12350000 0x1000>;
	power-domains = <&power 0>;
	};

	The node above defines a typical PM domain consumer device, which is located
	inside a PM domain with index 0 of a power controller represented by a node
	with the label "power".

	Optional properties:
	- required-opps: This contains phandle to an OPP node in another device's OPP
	table. It may contain an array of phandles, where each phandle points to an
	OPP of a different device. It should not contain multiple phandles to the OPP
	nodes in the same OPP table. This specifies the minimum required OPP of the
	device(s), whose OPP's phandle is present in this property, for the
	functioning of the current device at the current OPP (where this property is
	present).

	Example:
	- OPP table for domain provider that provides two domains.

	domain0_opp_table: opp-table0 {
	compatible = "operating-points-v2";

	domain0_opp_0: opp-1000000000 {
	opp-hz = /bits/ 64 <1000000000>;
	opp-microvolt = <975000 970000 985000>;
	};
	domain0_opp_1: opp-1100000000 {
	opp-hz = /bits/ 64 <1100000000>;
	opp-microvolt = <1000000 980000 1010000>;
	};
	};

	domain1_opp_table: opp-table1 {
	compatible = "operating-points-v2";

	domain1_opp_0: opp-1200000000 {
	opp-hz = /bits/ 64 <1200000000>;
	opp-microvolt = <975000 970000 985000>;
	};
	domain1_opp_1: opp-1300000000 {
	opp-hz = /bits/ 64 <1300000000>;
	opp-microvolt = <1000000 980000 1010000>;
	};
	};

	power: power-controller@12340000 {
	compatible = "foo,power-controller";
	reg = <0x12340000 0x1000>;
	#power-domain-cells = <1>;
	operating-points-v2 = <&domain0_opp_table>, <&domain1_opp_table>;
	};

	leaky-device0@12350000 {
	compatible = "foo,i-leak-current";
	reg = <0x12350000 0x1000>;
	power-domains = <&power 0>;
	required-opps = <&domain0_opp_0>;
	};

	leaky-device1@12350000 {
	compatible = "foo,i-leak-current";
	reg = <0x12350000 0x1000>;
	power-domains = <&power 1>;
	required-opps = <&domain1_opp_1>;
	};

	[1]. Documentation/devicetree/bindings/power/domain-idle-state.txt