Re: [PATCH 1/2] dt-bindings: clock: Add binding documentation for TI syscon gate clock

Vignesh Raghavendra
2019-04-09T07:56:18Z

Hi Rob,

On 28/03/19 6:01 PM, Rob Herring wrote:
> On Tue, Mar 12, 2019 at 02:35:17PM +0530, Vignesh Raghavendra wrote:
>> Add dt bindings for TI syscon gate clock.
>>
>> Signed-off-by: Vignesh Raghavendra <vigneshr@ti.com>
>> ---
>> .../bindings/clock/ti,syscon-gate-clock.txt | 35 +++++++++++++++++++
>> 1 file changed, 35 insertions(+)
>> create mode 100644 Documentation/devicetree/bindings/clock/ti,syscon-gate-clock.txt
>>
>> diff --git a/Documentation/devicetree/bindings/clock/ti,syscon-gate-clock.txt b/Documentation/devicetree/bindings/clock/ti,syscon-gate-clock.txt
>> new file mode 100644
>> index 000000000000..f2bc4281ddba
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/clock/ti,syscon-gate-clock.txt
>> @@ -0,0 +1,35 @@
>> +TI syscon gate clock
>> +
>> +The gate clock node must be provided inside a system controller node.
>> +
>> +Required:
>> +- comaptible: Must be "ti,syscon-gate-clock"
>> +- reg: Offset of register that controls the clock within syscon regmap
>> +- ti,clock-bit-idx: bit index that control gate/ungating of clock
>> +- clocks: phandle to the clock parent
>> +- #clock-cells: must be <0>
>> +
>> +Example:
>> + ctrlmmr_epwm_ctrl: syscon@104140{
>> + compatible = "syscon", "simple-bus";
>
> Can't be both of these...
>

These registers have bits that control other functionalities apart from
PWM clocks. Therefore, I modeled them as "syscon", "simple-bus";

Or is it recommended to use:
compatible = "syscon", "simple-mfd";

>> + reg = <0x0 0x104140 0x0 0x18>;
>> + ranges = <0x0 0x0 0x104140>;
>> + #address-cells = <1>;
>> + #size-cells = <0>;
>> +
>> + ehrpwm0_tbclk: clk@0 {
>> + compatible = "ti,syscon-gate-clock";
>> + reg = <0x0>;
>> + #clock-cells = <0>;
>> + clocks = <&k3_clks 40 0>;
>> + ti,clock-bit-idx = <0>;
>
> This would imply you have multiple nodes at one address which is
> discouraged.
>
>> + };
>
> We generally don't describe clocks as 1 clock per node. Give the parent
> a specific compatible and make it a clock provider.
>

Ok, I can change this to single clock node and use #clock-cells to pass
register offset of and bit index from each consumer:

ctrlmmr_epwm_ctrl: syscon@104140{
compatible = "syscon", "simple-mfd";
reg = <0x0 0x104140 0x0 0x18>;
ranges = <0x0 0x0 0x104140>;
#address-cells = <1>;
#size-cells = <0>;

ehrpwm_tbclk: clk {
compatible = "ti,syscon-gate-clock";
#clock-cells = <2>;
};
};

And consumer node:

ehrpwm1: pwm@3010000 {
compatible = "ti,am654-ehrpwm", "ti,am3352-ehrpwm";
#pwm-cells = <3>;
reg = <0x0 0x3000000 0x0 0x100>;
power-domains = <&k3_pds 40>;
clocks = <&ehrpwm_tbclk 4 0>; /* offset 4, bit 0 */
clock-names = "tbclk";
};

Would that be acceptable?

Regards
Vignesh

>> +
>> + ehrpwm1_tbclk: clk@4 {
>> + compatible = "ti,syscon-gate-clock";
>> + reg = <0x4>;
>> + #clock-cells = <0>;
>> + clocks = <&k3_clks 41 0>;
>> + ti,clock-bit-idx = <0>;
>> + };
>> + };
>> --
>> 2.21.0
>>