79 lines
2.8 KiB
Plaintext
79 lines
2.8 KiB
Plaintext
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* Generic PM domains
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System on chip designs are often divided into multiple PM domains that can be
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used for power gating of selected IP blocks for power saving by reduced leakage
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current.
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This device tree binding can be used to bind PM domain consumer devices with
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their PM domains provided by PM domain providers. A PM domain provider can be
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represented by any node in the device tree and can provide one or more PM
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domains. A consumer node can refer to the provider by a phandle and a set of
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phandle arguments (so called PM domain specifiers) of length specified by the
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#power-domain-cells property in the PM domain provider node.
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==PM domain providers==
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Required properties:
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- #power-domain-cells : Number of cells in a PM domain specifier;
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Typically 0 for nodes representing a single PM domain and 1 for nodes
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providing multiple PM domains (e.g. power controllers), but can be any value
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as specified by device tree binding documentation of particular provider.
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Optional properties:
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- power-domains : A phandle and PM domain specifier as defined by bindings of
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the power controller specified by phandle.
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Some power domains might be powered from another power domain (or have
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other hardware specific dependencies). For representing such dependency
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a standard PM domain consumer binding is used. When provided, all domains
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created by the given provider should be subdomains of the domain
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specified by this binding. More details about power domain specifier are
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available in the next section.
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Example:
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power: power-controller@12340000 {
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compatible = "foo,power-controller";
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reg = <0x12340000 0x1000>;
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#power-domain-cells = <1>;
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};
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The node above defines a power controller that is a PM domain provider and
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expects one cell as its phandle argument.
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Example 2:
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parent: power-controller@12340000 {
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compatible = "foo,power-controller";
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reg = <0x12340000 0x1000>;
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#power-domain-cells = <1>;
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};
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child: power-controller@12341000 {
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compatible = "foo,power-controller";
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reg = <0x12341000 0x1000>;
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power-domains = <&parent 0>;
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#power-domain-cells = <1>;
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};
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The nodes above define two power controllers: 'parent' and 'child'.
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Domains created by the 'child' power controller are subdomains of '0' power
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domain provided by the 'parent' power controller.
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==PM domain consumers==
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Required properties:
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- power-domains : A phandle and PM domain specifier as defined by bindings of
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the power controller specified by phandle.
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Example:
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leaky-device@12350000 {
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compatible = "foo,i-leak-current";
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reg = <0x12350000 0x1000>;
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power-domains = <&power 0>;
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};
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The node above defines a typical PM domain consumer device, which is located
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inside a PM domain with index 0 of a power controller represented by a node
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with the label "power".
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