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SPM AVS Wrapper 2 (SAW2)
The SAW2 is a wrapper around the Subsystem Power Manager (SPM) and the
Adaptive Voltage Scaling (AVS) hardware. The SPM is a programmable
power-controller that transitions a piece of hardware (like a processor or
subsystem) into and out of low power modes via a direct connection to
the PMIC. It can also be wired up to interact with other processors in the
system, notifying them when a low power state is entered or exited.
Multiple revisions of the SAW hardware are supported using these Device Nodes.
SAW2 revisions differ in the register offset and configuration data. Also, the
same revision of the SAW in different SoCs may have different configuration
data due the the differences in hardware capabilities. Hence the SoC name, the
version of the SAW hardware in that SoC and the distinction between cpu (big
or Little) or cache, may be needed to uniquely identify the SAW register
configuration and initialization data. The compatible string is used to
indicate this parameter.
- compatible:
Usage: required
Value type: <string>
Definition: Must have
A more specific value could be one of:
- reg:
Usage: required
Value type: <prop-encoded-array>
Definition: the first element specifies the base address and size of
the register region. An optional second element specifies
the base address and size of the alias register region.
- regulator:
Usage: optional
Value type: boolean
Definition: Indicates that this SPM device acts as a regulator device
device for the core (CPU or Cache) the SPM is attached
Example 1:
power-controller@2099000 {
compatible = "qcom,saw2";
reg = <0x02099000 0x1000>, <0x02009000 0x1000>;
Example 2:
saw0: power-controller@f9089000 {
compatible = "qcom,apq8084-saw2-v2.1-cpu", "qcom,saw2";
reg = <0xf9089000 0x1000>, <0xf9009000 0x1000>;