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SubjectRe: [PATCH 4/7] dt-bindings: chosen: Add clocksource and clockevent selection
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Hi,

On 10/09/2019 15:47, Claudiu Beznea wrote:
> From: Alexandre Belloni <alexandre.belloni@bootlin.com>
>
> Some timer drivers may behave either as clocksource or clockevent
> or both. Until now, in case of platforms with multiple hardware
> resources of the same type, the drivers were chosing the first
> registered hardware resource as clocksource/clockevent and the
> next one as clockevent/clocksource. Other were using different
> compatibles (one for each functionality, although its about the
> same hardware). Add DT bindings to be able to choose the
> functionality of a timer.
>
> Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
> Signed-off-by: Claudiu Beznea <claudiu.beznea@microchip.com>
> ---
> Documentation/devicetree/bindings/chosen.txt | 20 ++++++++++++++++++++
> 1 file changed, 20 insertions(+)
>
> diff --git a/Documentation/devicetree/bindings/chosen.txt b/Documentation/devicetree/bindings/chosen.txt
> index 45e79172a646..aad3034cdbdf 100644
> --- a/Documentation/devicetree/bindings/chosen.txt
> +++ b/Documentation/devicetree/bindings/chosen.txt
> @@ -135,3 +135,23 @@ e.g.
> linux,initrd-end = <0x82800000>;
> };
> };
> +
> +linux,clocksource and linux,clockevent
> +--------------------------------------
> +
> +Those nodes have a timer property. This property is a phandle to the timer to be
> +chosen as the clocksource or clockevent. This is only useful when the platform
> +has multiple identical timers and it is not possible to let linux make the
> +correct choice.
> +
> +/ {
> + chosen {
> + linux,clocksource {
> + timer = <&timer0>;
> + };
> +
> + linux,clockevent {
> + timer = <&timer1>;
> + };
> + };
> +};
>

Why not in aliases ?

aliases {
clocksource0 = &timer0;
clockevent0 = &timer1;
};

since we can have multiple of each, we should not limit ourselves to 1 clkevent
and 1 clksource.

In the aliases case, each driver would expose both capabilities, and the core would select
what to enable.

Neil

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