Documentation/devicetree/bindings/cpufreq/cpufreq-st.txt

Source file repositories/reference/linux-study-clean/Documentation/devicetree/bindings/cpufreq/cpufreq-st.txt

File Facts

System
Linux kernel
Corpus path
Documentation/devicetree/bindings/cpufreq/cpufreq-st.txt
Extension
.txt
Size
2402 bytes
Lines
90
Domain
Support Tooling And Documentation
Bucket
Documentation
Inferred role
Support Tooling And Documentation: documentation
Status
atlas-only

Why This File Exists

Repository support layer: documentation, build tooling, samples, user-space helper tools, generated initramfs support, licenses, and validation utilities.

Dependency Surface

Detected Declarations

Annotated Snippet

Binding for ST's CPUFreq driver
===============================

ST's CPUFreq driver attempts to read 'process' and 'version' attributes
from the SoC, then supplies the OPP framework with 'prop' and 'supported
hardware' information respectively.  The framework is then able to read
the DT and operate in the usual way.

Frequency Scaling only
----------------------

No vendor specific driver required for this.

Located in CPU's node:

- operating-points		: [See: ../power/opp-v1.yaml]

Example [safe]
--------------

cpus {
	cpu@0 {
				 /* kHz     uV   */
		operating-points = <1500000 0
				    1200000 0
				    800000  0
				    500000  0>;
	};
};

Dynamic Voltage and Frequency Scaling (DVFS)
--------------------------------------------

This requires the ST CPUFreq driver to supply 'process' and 'version' info.

Located in CPU's node:

- operating-points-v2		: [See ../power/opp-v2.yaml]

Example [unsafe]
----------------

cpus {
	cpu@0 {
		operating-points-v2	= <&cpu0_opp_table>;
	};
};

cpu0_opp_table: opp_table {
	compatible = "operating-points-v2";

	/* ############################################################### */
	/* # WARNING: Do not attempt to copy/replicate these nodes,      # */
	/* #          they are only to be supplied by the bootloader !!! # */
	/* ############################################################### */
	opp0 {
		/*			   Major       Minor       Substrate */
		/*			   2           all         all       */
		opp-supported-hw	= <0x00000004  0xffffffff  0xffffffff>;
		opp-hz			= /bits/ 64 <1500000000>;
		clock-latency-ns	= <10000000>;

		opp-microvolt-pcode0	= <1200000>;
		opp-microvolt-pcode1	= <1200000>;
		opp-microvolt-pcode2	= <1200000>;
		opp-microvolt-pcode3	= <1200000>;
		opp-microvolt-pcode4	= <1170000>;
		opp-microvolt-pcode5	= <1140000>;
		opp-microvolt-pcode6	= <1100000>;
		opp-microvolt-pcode7	= <1070000>;

Annotation

Implementation Notes