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 16Required properties: 17 - #power-domain-cells : Number of cells in a PM domain specifier; 18 Typically 0 for nodes representing a single PM domain and 1 for nodes 19 providing multiple PM domains (e.g. power controllers), but can be any value 20 as specified by device tree binding documentation of particular provider. 21 22Optional properties: 23 - power-domains : A phandle and PM domain specifier as defined by bindings of 24 the power controller specified by phandle. 25 Some power domains might be powered from another power domain (or have 26 other hardware specific dependencies). For representing such dependency 27 a standard PM domain consumer binding is used. When provided, all domains 28 created by the given provider should be subdomains of the domain 29 specified by this binding. More details about power domain specifier are 30 available in the next section. 31 32- domain-idle-states : A phandle of an idle-state that shall be soaked into a 33 generic domain power state. The idle state definitions are 34 compatible with domain-idle-state specified in [1]. phandles 35 that are not compatible with domain-idle-state will be 36 ignored. 37 The domain-idle-state property reflects the idle state of this PM domain and 38 not the idle states of the devices or sub-domains in the PM domain. Devices 39 and sub-domains have their own idle-states independent of the parent 40 domain's idle states. In the absence of this property, the domain would be 41 considered as capable of being powered-on or powered-off. 42 43- operating-points-v2 : Phandles to the OPP tables of power domains provided by 44 a power domain provider. If the provider provides a single power domain only 45 or all the power domains provided by the provider have identical OPP tables, 46 then this shall contain a single phandle. Refer to ../opp/opp.txt for more 47 information. 48 49Example: 50 51 power: power-controller@12340000 { 52 compatible = "foo,power-controller"; 53 reg = <0x12340000 0x1000>; 54 #power-domain-cells = <1>; 55 }; 56 57The node above defines a power controller that is a PM domain provider and 58expects one cell as its phandle argument. 59 60Example 2: 61 62 parent: power-controller@12340000 { 63 compatible = "foo,power-controller"; 64 reg = <0x12340000 0x1000>; 65 #power-domain-cells = <1>; 66 }; 67 68 child: power-controller@12341000 { 69 compatible = "foo,power-controller"; 70 reg = <0x12341000 0x1000>; 71 power-domains = <&parent 0>; 72 #power-domain-cells = <1>; 73 }; 74 75The nodes above define two power controllers: 'parent' and 'child'. 76Domains created by the 'child' power controller are subdomains of '0' power 77domain provided by the 'parent' power controller. 78 79Example 3: 80 parent: power-controller@12340000 { 81 compatible = "foo,power-controller"; 82 reg = <0x12340000 0x1000>; 83 #power-domain-cells = <0>; 84 domain-idle-states = <&DOMAIN_RET>, <&DOMAIN_PWR_DN>; 85 }; 86 87 child: power-controller@12341000 { 88 compatible = "foo,power-controller"; 89 reg = <0x12341000 0x1000>; 90 power-domains = <&parent>; 91 #power-domain-cells = <0>; 92 domain-idle-states = <&DOMAIN_PWR_DN>; 93 }; 94 95 DOMAIN_RET: state@0 { 96 compatible = "domain-idle-state"; 97 reg = <0x0>; 98 entry-latency-us = <1000>; 99 exit-latency-us = <2000>; 100 min-residency-us = <10000>; 101 }; 102 103 DOMAIN_PWR_DN: state@1 { 104 compatible = "domain-idle-state"; 105 reg = <0x1>; 106 entry-latency-us = <5000>; 107 exit-latency-us = <8000>; 108 min-residency-us = <7000>; 109 }; 110 111==PM domain consumers== 112 113Required properties: 114 - power-domains : A list of PM domain specifiers, as defined by bindings of 115 the power controller that is the PM domain provider. 116 117Example: 118 119 leaky-device@12350000 { 120 compatible = "foo,i-leak-current"; 121 reg = <0x12350000 0x1000>; 122 power-domains = <&power 0>; 123 }; 124 125 leaky-device@12351000 { 126 compatible = "foo,i-leak-current"; 127 reg = <0x12351000 0x1000>; 128 power-domains = <&power 0>, <&power 1> ; 129 }; 130 131The first example above defines a typical PM domain consumer device, which is 132located inside a PM domain with index 0 of a power controller represented by a 133node with the label "power". 134In the second example the consumer device are partitioned across two PM domains, 135the first with index 0 and the second with index 1, of a power controller that 136is represented by a node with the label "power. 137 138Optional properties: 139- required-opps: This contains phandle to an OPP node in another device's OPP 140 table. It may contain an array of phandles, where each phandle points to an 141 OPP of a different device. It should not contain multiple phandles to the OPP 142 nodes in the same OPP table. This specifies the minimum required OPP of the 143 device(s), whose OPP's phandle is present in this property, for the 144 functioning of the current device at the current OPP (where this property is 145 present). 146 147Example: 148- OPP table for domain provider that provides two domains. 149 150 domain0_opp_table: opp-table0 { 151 compatible = "operating-points-v2"; 152 153 domain0_opp_0: opp-1000000000 { 154 opp-hz = /bits/ 64 <1000000000>; 155 opp-microvolt = <975000 970000 985000>; 156 }; 157 domain0_opp_1: opp-1100000000 { 158 opp-hz = /bits/ 64 <1100000000>; 159 opp-microvolt = <1000000 980000 1010000>; 160 }; 161 }; 162 163 domain1_opp_table: opp-table1 { 164 compatible = "operating-points-v2"; 165 166 domain1_opp_0: opp-1200000000 { 167 opp-hz = /bits/ 64 <1200000000>; 168 opp-microvolt = <975000 970000 985000>; 169 }; 170 domain1_opp_1: opp-1300000000 { 171 opp-hz = /bits/ 64 <1300000000>; 172 opp-microvolt = <1000000 980000 1010000>; 173 }; 174 }; 175 176 power: power-controller@12340000 { 177 compatible = "foo,power-controller"; 178 reg = <0x12340000 0x1000>; 179 #power-domain-cells = <1>; 180 operating-points-v2 = <&domain0_opp_table>, <&domain1_opp_table>; 181 }; 182 183 leaky-device0@12350000 { 184 compatible = "foo,i-leak-current"; 185 reg = <0x12350000 0x1000>; 186 power-domains = <&power 0>; 187 required-opps = <&domain0_opp_0>; 188 }; 189 190 leaky-device1@12350000 { 191 compatible = "foo,i-leak-current"; 192 reg = <0x12350000 0x1000>; 193 power-domains = <&power 1>; 194 required-opps = <&domain1_opp_1>; 195 }; 196 197[1]. Documentation/devicetree/bindings/power/domain-idle-state.txt 198