Re: [v2 1/3] dt-bindings: Add bindings for aspeed pwm-tach.

From: Billy Tsai
Date: Thu Nov 03 2022 - 03:39:39 EST


On 2022/11/3, 2:19 AM, "Rob Herring" <robh@xxxxxxxxxx> wrote:

On Tue, Nov 1, 2022 at 10:21 PM Billy Tsai <billy_tsai@xxxxxxxxxxxxxx> wrote:

> That all sounds like requirements that you have which you should
> ensure the fan binding can support.

> I've already said to use the PWM binding in the fan binding exactly
> for the purpose of hooking up the PWMs to other things. Whether the
> tach controller is useful for something other than fans, I don't know.
> Seems less likely. The max6639 also has a tach controller. So if other
> uses are possible for you, then it could be possible for any other h/w
> like the max6639.

The linux kernel already have the similar binding:
https://github.com/torvalds/linux/blob/master/Documentation/devicetree/bindings/hwmon/pwm-fan.txt
Therefore, I want to reuse it and the pwm-fan.c instead of creating another similar fan binding and driver.
I am referring to the following files:
https://github.com/torvalds/linux/blob/master/Documentation/devicetree/bindings/mfd/kontron%2Csl28cpld.yaml
https://github.com/torvalds/linux/blob/master/Documentation/devicetree/bindings/pwm/kontron%2Csl28cpld-pwm.yaml
https://github.com/torvalds/linux/blob/master/Documentation/devicetree/bindings/hwmon/kontron%2Csl28cpld-hwmon.yaml
It will also reuse the pwm-fan instead creating it own pwm-fan binding for their hwmon(tach).
https://github.com/torvalds/linux/blob/master/arch/arm64/boot/dts/freescale/fsl-ls1028a-kontron-sl28-var3-ads2.dts#L20

Thanks

Best Regards,
Billy Tsai