Bindings/power/power_domain.txt

   1 * Generic PM domains
   2
   3 System on chip designs are often divided into multiple PM domains that can be
   4 used for power gating of selected IP blocks for power saving by reduced leakage
   5 current.
   6
   7 This device tree binding can be used to bind PM domain consumer devices with
   8 their PM domains provided by PM domain providers. A PM domain provider can be
   9 represented by any node in the device tree and can provide one or more PM
  10 domains. A consumer node can refer to the provider by a phandle and a set of
  11 phandle 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
  16 See power-domain.yaml.
  17
  18 ==PM domain consumers==
  19
  20 Required 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
  24 Optional 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
  30 Example:
  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
  46 The first example above defines a typical PM domain consumer device, which is
  47 located inside a PM domain with index 0 of a power controller represented by a
  48 node with the label "power".
  49 In the second example the consumer device are partitioned across two PM domains,
  50 the first with index 0 and the second with index 1, of a power controller that
  51 is represented by a node with the label "power".
  52
  53 Optional 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
  62 Example:
  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