power_domain.txt

  1* Generic PM domains
  2
  3System on chip designs are often divided into multiple PM domains that can be
  4used for power gating of selected IP blocks for power saving by reduced leakage
  5current.
  6
  7This device tree binding can be used to bind PM domain consumer devices with
  8their PM domains provided by PM domain providers. A PM domain provider can be
  9represented by any node in the device tree and can provide one or more PM
 10domains. A consumer node can refer to the provider by a phandle and a set of
 11phandle arguments (so called PM domain specifiers) of length specified by the
 12#power-domain-cells property in the PM domain provider node.
 13
 14==PM domain providers==
 15
 16See power-domain.yaml.
 17
 18==PM domain consumers==
 19
 20Required properties:
 21 - power-domains : A list of PM domain specifiers, as defined by bindings of
 22		the power controller that is the PM domain provider.
 23
 24Optional properties:
 25 - power-domain-names : A list of power domain name strings sorted in the same
 26		order as the power-domains property. Consumers drivers will use
 27		power-domain-names to match power domains with power-domains
 28		specifiers.
 29
 30Example:
 31
 32	leaky-device@12350000 {
 33		compatible = "foo,i-leak-current";
 34		reg = <0x12350000 0x1000>;
 35		power-domains = <&power 0>;
 36		power-domain-names = "io";
 37	};
 38
 39	leaky-device@12351000 {
 40		compatible = "foo,i-leak-current";
 41		reg = <0x12351000 0x1000>;
 42		power-domains = <&power 0>, <&power 1> ;
 43		power-domain-names = "io", "clk";
 44	};
 45
 46The first example above defines a typical PM domain consumer device, which is
 47located inside a PM domain with index 0 of a power controller represented by a
 48node with the label "power".
 49In the second example the consumer device are partitioned across two PM domains,
 50the first with index 0 and the second with index 1, of a power controller that
 51is represented by a node with the label "power".
 52
 53Optional properties:
 54- required-opps: This contains phandle to an OPP node in another device's OPP
 55  table. It may contain an array of phandles, where each phandle points to an
 56  OPP of a different device. It should not contain multiple phandles to the OPP
 57  nodes in the same OPP table. This specifies the minimum required OPP of the
 58  device(s), whose OPP's phandle is present in this property, for the
 59  functioning of the current device at the current OPP (where this property is
 60  present).
 61
 62Example:
 63- OPP table for domain provider that provides two domains.
 64
 65	domain0_opp_table: opp-table0 {
 66		compatible = "operating-points-v2";
 67
 68		domain0_opp_0: opp-1000000000 {
 69			opp-hz = /bits/ 64 <1000000000>;
 70			opp-microvolt = <975000 970000 985000>;
 71		};
 72		domain0_opp_1: opp-1100000000 {
 73			opp-hz = /bits/ 64 <1100000000>;
 74			opp-microvolt = <1000000 980000 1010000>;
 75		};
 76	};
 77
 78	domain1_opp_table: opp-table1 {
 79		compatible = "operating-points-v2";
 80
 81		domain1_opp_0: opp-1200000000 {
 82			opp-hz = /bits/ 64 <1200000000>;
 83			opp-microvolt = <975000 970000 985000>;
 84		};
 85		domain1_opp_1: opp-1300000000 {
 86			opp-hz = /bits/ 64 <1300000000>;
 87			opp-microvolt = <1000000 980000 1010000>;
 88		};
 89	};
 90
 91	power: power-controller@12340000 {
 92		compatible = "foo,power-controller";
 93		reg = <0x12340000 0x1000>;
 94		#power-domain-cells = <1>;
 95		operating-points-v2 = <&domain0_opp_table>, <&domain1_opp_table>;
 96	};
 97
 98	leaky-device0@12350000 {
 99		compatible = "foo,i-leak-current";
100		reg = <0x12350000 0x1000>;
101		power-domains = <&power 0>;
102		required-opps = <&domain0_opp_0>;
103	};
104
105	leaky-device1@12350000 {
106		compatible = "foo,i-leak-current";
107		reg = <0x12350000 0x1000>;
108		power-domains = <&power 1>;
109		required-opps = <&domain1_opp_1>;
110	};
111
112[1]. Documentation/devicetree/bindings/power/domain-idle-state.yaml