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
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.
14 ==PM domain providers==
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.
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.
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
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.
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
51 power: power-controller@12340000 {
52 compatible = "foo,power-controller";
53 reg = <0x12340000 0x1000>;
54 #power-domain-cells = <1>;
57 The node above defines a power controller that is a PM domain provider and
58 expects one cell as its phandle argument.
62 parent: power-controller@12340000 {
63 compatible = "foo,power-controller";
64 reg = <0x12340000 0x1000>;
65 #power-domain-cells = <1>;
68 child: power-controller@12341000 {
69 compatible = "foo,power-controller";
70 reg = <0x12341000 0x1000>;
71 power-domains = <&parent 0>;
72 #power-domain-cells = <1>;
75 The nodes above define two power controllers: 'parent' and 'child'.
76 Domains created by the 'child' power controller are subdomains of '0' power
77 domain provided by the 'parent' power controller.
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>;
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>;
96 compatible = "domain-idle-state";
98 entry-latency-us = <1000>;
99 exit-latency-us = <2000>;
100 min-residency-us = <10000>;
103 DOMAIN_PWR_DN: state@1 {
104 compatible = "domain-idle-state";
106 entry-latency-us = <5000>;
107 exit-latency-us = <8000>;
108 min-residency-us = <7000>;
111 ==PM domain consumers==
114 - power-domains : A list of PM domain specifiers, as defined by bindings of
115 the power controller that is the PM domain provider.
118 - power-domain-names : A list of power domain name strings sorted in the same
119 order as the power-domains property. Consumers drivers will use
120 power-domain-names to match power domains with power-domains
125 leaky-device@12350000 {
126 compatible = "foo,i-leak-current";
127 reg = <0x12350000 0x1000>;
128 power-domains = <&power 0>;
129 power-domain-names = "io";
132 leaky-device@12351000 {
133 compatible = "foo,i-leak-current";
134 reg = <0x12351000 0x1000>;
135 power-domains = <&power 0>, <&power 1> ;
136 power-domain-names = "io", "clk";
139 The first example above defines a typical PM domain consumer device, which is
140 located inside a PM domain with index 0 of a power controller represented by a
141 node with the label "power".
142 In the second example the consumer device are partitioned across two PM domains,
143 the first with index 0 and the second with index 1, of a power controller that
144 is represented by a node with the label "power".
147 - required-opps: This contains phandle to an OPP node in another device's OPP
148 table. It may contain an array of phandles, where each phandle points to an
149 OPP of a different device. It should not contain multiple phandles to the OPP
150 nodes in the same OPP table. This specifies the minimum required OPP of the
151 device(s), whose OPP's phandle is present in this property, for the
152 functioning of the current device at the current OPP (where this property is
156 - OPP table for domain provider that provides two domains.
158 domain0_opp_table: opp-table0 {
159 compatible = "operating-points-v2";
161 domain0_opp_0: opp-1000000000 {
162 opp-hz = /bits/ 64 <1000000000>;
163 opp-microvolt = <975000 970000 985000>;
165 domain0_opp_1: opp-1100000000 {
166 opp-hz = /bits/ 64 <1100000000>;
167 opp-microvolt = <1000000 980000 1010000>;
171 domain1_opp_table: opp-table1 {
172 compatible = "operating-points-v2";
174 domain1_opp_0: opp-1200000000 {
175 opp-hz = /bits/ 64 <1200000000>;
176 opp-microvolt = <975000 970000 985000>;
178 domain1_opp_1: opp-1300000000 {
179 opp-hz = /bits/ 64 <1300000000>;
180 opp-microvolt = <1000000 980000 1010000>;
184 power: power-controller@12340000 {
185 compatible = "foo,power-controller";
186 reg = <0x12340000 0x1000>;
187 #power-domain-cells = <1>;
188 operating-points-v2 = <&domain0_opp_table>, <&domain1_opp_table>;
191 leaky-device0@12350000 {
192 compatible = "foo,i-leak-current";
193 reg = <0x12350000 0x1000>;
194 power-domains = <&power 0>;
195 required-opps = <&domain0_opp_0>;
198 leaky-device1@12350000 {
199 compatible = "foo,i-leak-current";
200 reg = <0x12350000 0x1000>;
201 power-domains = <&power 1>;
202 required-opps = <&domain1_opp_1>;
205 [1]. Documentation/devicetree/bindings/power/domain-idle-state.txt