[v6 2/4] dt-bindings: hwmon: Add ASPEED TACH Control documentation

[Guenter Roeck <linux@roeck-us.net>]

On 6/7/23 23:21, Billy Tsai wrote:
>  ??????? > The code says:
> 
>  ??????? > In Aspeed AST2600 SoC features 16 TACH controllers, with each
> 
>  ??????? > controller capable of supporting up to 1 input.
> 
>  ??????? > which is a bit different. I guess there are no examples anymore,
> 
>  ??????? > but I'd really like to see how this looks like in the devicetree file,
> 
>  ??????? > and how the driver is supposed to distinguish/select the 16 inputs.
> 
> Hi Roeck,
> 
> The node in the devicetree file will looks like following:
> 
> tach0: tach0 at 1e610008 {
> 
>  ??????? compatible = "aspeed,ast2600-tach";
> 
>  ??????? reg = <0x1e610008 0x8>;
> 
>  ??????? #address-cells = <1>;
> 
>  ??????? #size-cells = <0>;
> 
>  ??????? pinctrl-names = "default";
> 
>  ??????? pinctrl-0 = <&pinctrl_tach0_default>;
> 
>  ??????? clocks = <&syscon ASPEED_CLK_AHB>;
> 
>  ??????? resets = <&syscon ASPEED_RESET_PWM>;
> 
>  ??????? status = "disabled";
> 
> };
> 

Neither reg nor pinctrl is mentioned in the bindings. Maybe that is not needed nowadays,
but I find it confusing.

Either case, it is highly unusual that there would be 16 instances of this device
instead of one. Why is this done ? It doesn't really make sense to me.

Guenter