Re: [PATCH v2 1/4] dt-bindings: hwmon: Add Aspeed AST2600 PWM/Fan

Troy Lee
2021-01-15T01:49:34Z

Hi Rob,

Thanks for reviewing.

The 01/14/2021 22:13, Rob Herring wrote:
> On Wed, Jan 13, 2021 at 07:08:45AM +0000, Troy Lee wrote:
> > We add binding for supporting a new AST2600 PWM/Fan hwmon driver.
> >
> > Changes since v1:
> > - dt binding with DT schema format
> >
> > Signed-off-by: Troy Lee <troy_lee@aspeedtech.com>
> > ---
> > .../hwmon/aspeed,ast2600-pwm-tachometer.yaml | 137 ++++++++++++++++++
> > 1 file changed, 137 insertions(+)
> > create mode 100644 Documentation/devicetree/bindings/hwmon/aspeed,ast2600-pwm-tachometer.yaml
> >
> > diff --git a/Documentation/devicetree/bindings/hwmon/aspeed,ast2600-pwm-tachometer.yaml b/Documentation/devicetree/bindings/hwmon/aspeed,ast2600-pwm-tachometer.yaml
> > new file mode 100644
> > index 000000000000..b84076a4a338
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/hwmon/aspeed,ast2600-pwm-tachometer.yaml
> > @@ -0,0 +1,137 @@
> > +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> > +%YAML 1.2
> > +---
> > +
> > +$id: http://devicetree.org/schemas/hwmon/aspeed,ast2600-pwm-tachometer.yaml#
> > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > +
> > +title: ASPEED AST2600 PWM and Fan Tacho controller device driver
> > +
> > +maintainers:
> > + - Ryan Chen <ryan_chen@aspeedtech.com>
> > +
> > +description: |
> > + The ASPEED PWM controller can support upto 16 PWM outputs. The ASPEED Fan Tacho
> > + controller can support upto 16 Fan tachometer inputs.
> > + There can be upto 16 fans supported. Each fan can have one PWM output and
> > + one Fan tach inputs.
> > +
> > +properties:
> > + compatible:
> > + const: aspeed,ast2600-pwm-tachometer
> > +
> > + "#address-cells":
> > + const: 1
> > +
> > + "#size-cells":
> > + const: 0
> > +
> > + "#cooling-cells":
> > + const: 2
> > +
> > + reg:
> > + description:
> > + Address and length of the register set for the device.
>
> No need for generic descriptions. That's every 'reg'.
>
> What you need is how many entries and what each one is if more than 1.
> If only 1, then just 'maxItems: 1'
>
> > +
> > + clocks:
> > + description:
> > + phandle to clock provider with the clock number in the second cell
>
> Same here.
>
> > +
> > + resets:
> > + description:
> > + phandle to reset controller with the reset number in the second cell
>
> And here.
>
> > +
> > +patternProperties:
> > + "@[0-9]+$":
>
> If every node is a fan and there are up to 16:
>
> ^fan@[0-9a-f]$
>
I will update these in v3 patch set.

> > + type: object
> > + description:
> > + Under fan subnode there can upto 16 child nodes, with each child node
> > + representing a fan. There are 16 fans each fan can have one PWM port and one
> > + Fan tach inputs.
> > + For PWM port can be configured cooling-levels to create cooling device.
> > + Cooling device could be bound to a thermal zone for the thermal control.
> > +
> > + properties:
> > + reg:
> > + minimum: 0
> > + maximum: 15
> > + description:
> > + This property identify the PWM control channel of this fan.
> > +
> > + fan-tach-ch:
> > + $ref: /schemas/types.yaml#/definitions/uint8
> > + minimum: 0
> > + maximum: 15
> > + description:
> > + This property identify the fan tach input channel.
> > +
> > + pulses-per-revolution:
> > + $ref: /schemas/types.yaml#/definitions/uint32
> > + default: 2
> > + minimum: 1
> > + description:
> > + Specify tacho pulse per revolution of the fan.
> > +
> > + cooling-levels:
> > + description:
> > + PWM duty cycle values in a range from 0 to 255
> > + which correspond to thermal cooling states.
> > +
> > + aspeed,pwm-freq:
> > + $ref: /schemas/types.yaml#/definitions/uint32
> > + default: 25000
> > + minimum: 24
> > + maximum: 780000
> > + description:
> > + Specify the frequency of PWM.
>
> Units? Use a unit suffix and then drop the $ref.
>
I'll change it to pwm-freq-hz.

> > +
> > + aspeed,inverse-pin:
> > + type: boolean
> > + description:
> > + Inverse PWM output signal.
> > +
> > + aspeed,falling-point:
> > + $ref: /schemas/types.yaml#/definitions/uint8
> > + default: 10
> > + minimum: 0
> > + maximum: 255
>
> 0-255 is already the range of uint8, so drop.
>
I'll drop it in v3.

Thanks,
Troy Lee
> > + description:
> > + Initialize the pulse width.
> > +
> > + required:
> > + - fan-tach-ch
> > + - reg
> > +
> > + additionalProperties: true
> > +
> > +required:
> > + - compatible
> > + - reg
> > +
> > +additionalProperties: false
> > +
> > +examples:
> > + - |
> > + pwm_tacho: pwm-tacho-controller@1e610000 {
> > + compatible = "aspeed,ast2600-pwm-tachometer";
> > + #address-cells = <1>;
> > + #size-cells = <0>;
> > + reg = <0x1e610000 0x100>;
> > +
> > + fan@1 {
> > + reg = <0x00>;
> > + aspeed,pwm-freq = <25000>;
> > + cooling-levels = /bits/ 8 <125 151 177 203 229 255>;
> > + fan-tach-ch = /bits/ 8 <0x00>;
> > + pulses-per-revolution = <2>;
> > + };
> > +
> > + fan@2 {
> > + reg = <0x01>;
> > + aspeed,pwm-freq = <25000>;
> > + cooling-levels = /bits/ 8 <125 151 177 203 229 255>;
> > + fan-tach-ch = /bits/ 8 <0x01>;
> > + pulses-per-revolution = <2>;
> > + };
> > + };
> > +...
> > --
> > 2.25.1
> >