Re: [PATCH v4 2/4] Documentation: dt: add bindings for ti-cpufreq

[Rob Herring <robh-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>]

On Tue, Jan 17, 2017 at 07:18:06AM -0600, Dave Gerlach wrote:
> Add the device tree bindings document for the TI CPUFreq/OPP driver
> on AM33xx, AM43xx, DRA7xx, and AM57xx SoCs. The operating-points-v2
> binding allows us to provide an opp-supported-hw property for each OPP
> to define when it is available. This driver is responsible for reading
> and parsing registers to determine which OPPs can be selectively enabled
> based on the specific SoC in use by matching against the opp-supported-hw
> data.
> 
> Signed-off-by: Dave Gerlach <d-gerlach-l0cyMroinI0@public.gmane.org>
> ---
> v3->v4:
> 	Update to simplify binding, only use "syscon" now to pass control
> 	module register space and let driver handle offsets.
> 
>  .../devicetree/bindings/cpufreq/ti-cpufreq.txt     | 128 +++++++++++++++++++++
>  1 file changed, 128 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/cpufreq/ti-cpufreq.txt
> 
> diff --git a/Documentation/devicetree/bindings/cpufreq/ti-cpufreq.txt b/Documentation/devicetree/bindings/cpufreq/ti-cpufreq.txt
> new file mode 100644
> index 000000000000..58efa4c72545
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/cpufreq/ti-cpufreq.txt
> @@ -0,0 +1,128 @@
> +TI CPUFreq and OPP bindings
> +================================
> +
> +Certain TI SoCs, like those in the am335x, am437x, am57xx, and dra7xx
> +families support different OPPs depending on the silicon variant in use.
> +The ti-cpufreq driver can use revision and an efuse value from the SoC to
> +provide the OPP framework with supported hardware information. This is
> +used to determine which OPPs from the operating-points-v2 table get enabled
> +when it is parsed by the OPP framework.
> +
> +Required properties:
> +--------------------
> +In 'cpus' nodes:
> +- operating-points-v2: Phandle to the operating-points-v2 table to use.
> +
> +In 'operating-points-v2' table:
> +- compatible: Should be
> +	- 'operating-points-v2-ti-cpu' for am335x, am43xx, and dra7xx/am57xx SoCs
> +- syscon: A phandle pointing to a syscon node representing the control module
> +	  register space of the SoC.
> +
> +Optional properties:
> +--------------------
> +For each opp entry in 'operating-points-v2' table:
> +- opp-supported-hw: Two bitfields indicating:
> +	1. Which revision of the SoC the OPP is supported by
> +	2. Which eFuse bits indicate this OPP is available
> +
> +	A bitwise AND is performed against these values and if any bit
> +	matches, the OPP gets enabled.
> +
> +Example:
> +--------
> +
> +/* From arch/arm/boot/dts/am33xx.dtsi */
> +cpus {
> +	#address-cells = <1>;
> +	#size-cells = <0>;
> +	cpu@0 {
> +		compatible = "arm,cortex-a8";
> +		device_type = "cpu";
> +		reg = <0>;
> +
> +		operating-points-v2 = <&cpu0_opp_table>;
> +
> +		clocks = <&dpll_mpu_ck>;
> +		clock-names = "cpu";
> +
> +		clock-latency = <300000>; /* From omap-cpufreq driver */
> +	};
> +};
> +
> +/*
> + * cpu0 has different OPPs depending on SoC revision and some on revisions
> + * 0x2 and 0x4 have eFuse bits that indicate if they are available or not
> + */
> +cpu0_opp_table: opp_table0 {

Just "opp-table {"

> +	compatible = "operating-points-v2-ti-cpu";
> +	syscon = <&scm_conf>;
> +
> +	/*
> +	 * The three following nodes are marked with opp-suspend
> +	 * because they can not be enabled simultaneously on a
> +	 * single SoC.
> +	 */
> +	opp50@300000000 {

What's the 50, 100, 120 in the names?

> +		opp-hz = /bits/ 64 <300000000>;
> +		opp-microvolt = <950000 931000 969000>;
> +		opp-supported-hw = <0x06 0x0010>;
> +		opp-suspend;
> +	};
> +
> +	opp100@275000000 {
> +		opp-hz = /bits/ 64 <275000000>;
> +		opp-microvolt = <1100000 1078000 1122000>;
> +		opp-supported-hw = <0x01 0x00FF>;
> +		opp-suspend;
> +	};
> +
> +	opp100@300000000 {
> +		opp-hz = /bits/ 64 <300000000>;
> +		opp-microvolt = <1100000 1078000 1122000>;
> +		opp-supported-hw = <0x06 0x0020>;
> +		opp-suspend;
> +	};
> +
> +	opp100@500000000 {
> +		opp-hz = /bits/ 64 <500000000>;
> +		opp-microvolt = <1100000 1078000 1122000>;
> +		opp-supported-hw = <0x01 0xFFFF>;
> +	};
> +
> +	opp100@600000000 {
> +		opp-hz = /bits/ 64 <600000000>;
> +		opp-microvolt = <1100000 1078000 1122000>;
> +		opp-supported-hw = <0x06 0x0040>;
> +	};
> +
> +	opp120@600000000 {
> +		opp-hz = /bits/ 64 <600000000>;
> +		opp-microvolt = <1200000 1176000 1224000>;
> +		opp-supported-hw = <0x01 0xFFFF>;
> +	};
> +
> +	opp120@720000000 {
> +		opp-hz = /bits/ 64 <720000000>;
> +		opp-microvolt = <1200000 1176000 1224000>;
> +		opp-supported-hw = <0x06 0x0080>;
> +	};
> +
> +	oppturbo@720000000 {
> +		opp-hz = /bits/ 64 <720000000>;
> +		opp-microvolt = <1260000 1234800 1285200>;
> +		opp-supported-hw = <0x01 0xFFFF>;
> +	};
> +
> +	oppturbo@800000000 {
> +		opp-hz = /bits/ 64 <800000000>;
> +		opp-microvolt = <1260000 1234800 1285200>;
> +		opp-supported-hw = <0x06 0x0100>;
> +	};
> +
> +	oppnitro@1000000000 {
> +		opp-hz = /bits/ 64 <1000000000>;
> +		opp-microvolt = <1325000 1298500 1351500>;
> +		opp-supported-hw = <0x04 0x0200>;
> +	};
> +};
> -- 
> 2.11.0
> 
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