Re: [PATCH v7 3/3] dt-bindings: ap806: document gpio marvell,pwm-offset property
From: Linus Walleij <hidden>
Date: 2021-01-12 08:50:26
Also in:
linux-devicetree, linux-gpio, linux-pwm
Hi Baruch, this caught my eye: On Mon, Jan 11, 2021 at 12:47 PM Baruch Siach [off-list ref] wrote:
Update the example as well. Add the '#pwm-cells' and 'clocks' properties for a complete working example. Reviewed-by: Rob Herring <robh@kernel.org> Signed-off-by: Baruch Siach <baruch@tkos.co.il>
(...)
+Optional properties: + +- marvell,pwm-offset: offset address of PWM duration control registers inside + the syscon block
(...)
quoted hunk ↗ jump to hunk
ap_syscon: system-controller@6f4000 { compatible = "syscon", "simple-mfd";@@ -101,6 +106,9 @@ ap_syscon: system-controller@6f4000 { gpio-controller; #gpio-cells = <2>; gpio-ranges = <&ap_pinctrl 0 0 19>; + marvell,pwm-offset = <0x10c0>;
This seems to be one of those cases where we start to encode things related to the hardware variant into the device tree. Is this just documenting ABI that was introduced in the past and we can not do anything about now? In that case it is OK I suppose. For a new binding we would certainly require that the system controller provide a specific tertiary compatible string for this, lest we disguise the not-so-simple system controller as "simple-mfd" so: compatible = "syscon", "simple-mfd", "my-silicon-id"; Then detect the PWM offset by using if(of_device_is_compatibe(np, "my-silicon-id")) in the code rather than parsing any marvell,pwm-offset property. Yours, Linus Walleij _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel