projects / deliverable / linux.git / blame
| Commit | Line | Data |
|---|---|---|
| aa42240a TF |
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 | Required 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 | ||
| dbe67543 MS |
22 | Optional 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 | ||
| aa42240a TF |
32 | Example: |
| 33 | ||
| 34 | power: power-controller@12340000 { | |
| 35 | compatible = "foo,power-controller"; | |
| 36 | reg = <0x12340000 0x1000>; | |
| 37 | #power-domain-cells = <1>; | |
| 38 | }; | |
| 39 | ||
| 40 | The node above defines a power controller that is a PM domain provider and | |
| 41 | expects one cell as its phandle argument. | |
| 42 | ||
| dbe67543 MS |
43 | Example 2: |
| 44 | ||
| 45 | parent: power-controller@12340000 { | |
| 46 | compatible = "foo,power-controller"; | |
| 47 | reg = <0x12340000 0x1000>; | |
| 48 | #power-domain-cells = <1>; | |
| 49 | }; | |
| 50 | ||
| 51 | child: power-controller@12340000 { | |
| 52 | compatible = "foo,power-controller"; | |
| 53 | reg = <0x12341000 0x1000>; | |
| 54 | power-domains = <&parent 0>; | |
| 55 | #power-domain-cells = <1>; | |
| 56 | }; | |
| 57 | ||
| 58 | The nodes above define two power controllers: 'parent' and 'child'. | |
| 59 | Domains created by the 'child' power controller are subdomains of '0' power | |
| 60 | domain provided by the 'parent' power controller. | |
| 61 | ||
| aa42240a TF |
62 | ==PM domain consumers== |
| 63 | ||
| 64 | Required properties: | |
| 65 | - power-domains : A phandle and PM domain specifier as defined by bindings of | |
| 66 | the power controller specified by phandle. | |
| 67 | ||
| 68 | Example: | |
| 69 | ||
| 70 | leaky-device@12350000 { | |
| 71 | compatible = "foo,i-leak-current"; | |
| 72 | reg = <0x12350000 0x1000>; | |
| 73 | power-domains = <&power 0>; | |
| 74 | }; | |
| 75 | ||
| 76 | The node above defines a typical PM domain consumer device, which is located | |
| 77 | inside a PM domain with index 0 of a power controller represented by a node | |
| 78 | with the label "power". |