tjh.dev
Linux kernel mirror (for testing)
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1SPM AVS Wrapper 2 (SAW2)
2
3The SAW2 is a wrapper around the Subsystem Power Manager (SPM) and the
4Adaptive Voltage Scaling (AVS) hardware. The SPM is a programmable
5power-controller that transitions a piece of hardware (like a processor or
6subsystem) into and out of low power modes via a direct connection to
7the PMIC. It can also be wired up to interact with other processors in the
8system, notifying them when a low power state is entered or exited.
9
10Multiple revisions of the SAW hardware are supported using these Device Nodes.
11SAW2 revisions differ in the register offset and configuration data. Also, the
12same revision of the SAW in different SoCs may have different configuration
13data due the the differences in hardware capabilities. Hence the SoC name, the
14version of the SAW hardware in that SoC and the distinction between cpu (big
15or Little) or cache, may be needed to uniquely identify the SAW register
16configuration and initialization data. The compatible string is used to
17indicate this parameter.
18
19PROPERTIES
20
21- compatible:
22 Usage: required
23 Value type: <string>
24 Definition: Must have
25 "qcom,saw2"
26 A more specific value could be one of:
27 "qcom,apq8064-saw2-v1.1-cpu"
28 "qcom,msm8974-saw2-v2.1-cpu"
29 "qcom,apq8084-saw2-v2.1-cpu"
30
31- reg:
32 Usage: required
33 Value type: <prop-encoded-array>
34 Definition: the first element specifies the base address and size of
35 the register region. An optional second element specifies
36 the base address and size of the alias register region.
37
38- regulator:
39 Usage: optional
40 Value type: boolean
41 Definition: Indicates that this SPM device acts as a regulator device
42 device for the core (CPU or Cache) the SPM is attached
43 to.
44
45Example 1:
46
47 power-controller@2099000 {
48 compatible = "qcom,saw2";
49 reg = <0x02099000 0x1000>, <0x02009000 0x1000>;
50 regulator;
51 };
52
53Example 2:
54 saw0: power-controller@f9089000 {
55 compatible = "qcom,apq8084-saw2-v2.1-cpu", "qcom,saw2";
56 reg = <0xf9089000 0x1000>, <0xf9009000 0x1000>;
57 };