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
117Optional properties:
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
121		specifiers.
122
123Example:
124
125	leaky-device@12350000 {
126		compatible = "foo,i-leak-current";
127		reg = <0x12350000 0x1000>;
128		power-domains = <&power 0>;
129		power-domain-names = "io";
130	};
131
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";
137	};
138
139The first example above defines a typical PM domain consumer device, which is
140located inside a PM domain with index 0 of a power controller represented by a
141node with the label "power".
142In the second example the consumer device are partitioned across two PM domains,
143the first with index 0 and the second with index 1, of a power controller that
144is represented by a node with the label "power".
145
146Optional properties:
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
153  present).
154
155Example:
156- OPP table for domain provider that provides two domains.
157
158	domain0_opp_table: opp-table0 {
159		compatible = "operating-points-v2";
160
161		domain0_opp_0: opp-1000000000 {
162			opp-hz = /bits/ 64 <1000000000>;
163			opp-microvolt = <975000 970000 985000>;
164		};
165		domain0_opp_1: opp-1100000000 {
166			opp-hz = /bits/ 64 <1100000000>;
167			opp-microvolt = <1000000 980000 1010000>;
168		};
169	};
170
171	domain1_opp_table: opp-table1 {
172		compatible = "operating-points-v2";
173
174		domain1_opp_0: opp-1200000000 {
175			opp-hz = /bits/ 64 <1200000000>;
176			opp-microvolt = <975000 970000 985000>;
177		};
178		domain1_opp_1: opp-1300000000 {
179			opp-hz = /bits/ 64 <1300000000>;
180			opp-microvolt = <1000000 980000 1010000>;
181		};
182	};
183
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>;
189	};
190
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>;
196	};
197
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>;
203	};
204
205[1]. Documentation/devicetree/bindings/power/domain-idle-state.txt
206