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

[Dave Gerlach]

On 01/19/2017 12:07 PM, Rob Herring wrote:
> 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 at ti.com>
>> ---
>> 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 at 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 {"

Ok.

>
>> +	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 at 300000000 {
>
> What's the 50, 100, 120 in the names?

Those are the names of the OPPs given in Table 5-7 of the AM335x data 
manual, seen here http://www.ti.com/lit/ds/symlink/am3359.pdf . I 
typically reference the table and document in the commit message of the 
actual DT patches but didn't here for the binding.

Regards,
Dave

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