linux-kernel - Re: [PATCH v1] riscv: dts: sifive unleashed: Add PWM controlled LEDs

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Date:   Fri, 28 Oct 2022 15:47:58 -0700 (PDT)
From:   Palmer Dabbelt <palmer@...belt.com>
To:     emil.renner.berthing@...onical.com
CC:     linux-riscv@...ts.infradead.org, robh+dt@...nel.org,
        krzysztof.kozlowski+dt@...aro.org,
        Paul Walmsley <paul.walmsley@...ive.com>,
        alexandre.ghiti@...onical.com, bin.meng@...driver.com,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject:     Re: [PATCH v1] riscv: dts: sifive unleashed: Add PWM controlled LEDs

On Wed, 12 Oct 2022 04:09:28 PDT (-0700), emil.renner.berthing@...onical.com wrote:
> This adds the 4 PWM controlled green LEDs to the HiFive Unleashed device
> tree. The schematic doesn't specify any special function for the LEDs,
> so they're added here without any default triggers and named d1, d2, d3
> and d4 just like in the schematic.
>
> Signed-off-by: Emil Renner Berthing <emil.renner.berthing@...onical.com>
> ---
>
> Yes this board is old, but I'm trying to get rid of custom riscv patches in
> the Ubuntu kernel.

IMO fixing stuff for old boards is great, particularly if they're broken 
upstream but supported by distro kernels -- that's kind of a messy spot 
to be in.

>  .../boot/dts/sifive/hifive-unleashed-a00.dts  | 38 +++++++++++++++++++
>  1 file changed, 38 insertions(+)
>
> diff --git a/arch/riscv/boot/dts/sifive/hifive-unleashed-a00.dts b/arch/riscv/boot/dts/sifive/hifive-unleashed-a00.dts
> index ced0d4e47938..900a50526d77 100644
> --- a/arch/riscv/boot/dts/sifive/hifive-unleashed-a00.dts
> +++ b/arch/riscv/boot/dts/sifive/hifive-unleashed-a00.dts
> @@ -3,6 +3,8 @@
>
>  #include "fu540-c000.dtsi"
>  #include <dt-bindings/gpio/gpio.h>
> +#include <dt-bindings/leds/common.h>
> +#include <dt-bindings/pwm/pwm.h>
>
>  /* Clock frequency (in Hz) of the PCB crystal for rtcclk */
>  #define RTCCLK_FREQ		1000000
> @@ -42,6 +44,42 @@ gpio-restart {
>  		compatible = "gpio-restart";
>  		gpios = <&gpio 10 GPIO_ACTIVE_LOW>;
>  	};
> +
> +	led-controller {
> +		compatible = "pwm-leds";
> +
> +		led-d1 {
> +			pwms = <&pwm0 0 7812500 PWM_POLARITY_INVERTED>;
> +			active-low;
> +			color = <LED_COLOR_ID_GREEN>;
> +			max-brightness = <255>;
> +			label = "d1";
> +		};
> +
> +		led-d2 {
> +			pwms = <&pwm0 1 7812500 PWM_POLARITY_INVERTED>;
> +			active-low;
> +			color = <LED_COLOR_ID_GREEN>;
> +			max-brightness = <255>;
> +			label = "d2";
> +		};
> +
> +		led-d3 {
> +			pwms = <&pwm0 2 7812500 PWM_POLARITY_INVERTED>;
> +			active-low;
> +			color = <LED_COLOR_ID_GREEN>;
> +			max-brightness = <255>;
> +			label = "d3";
> +		};
> +
> +		led-d4 {
> +			pwms = <&pwm0 3 7812500 PWM_POLARITY_INVERTED>;
> +			active-low;
> +			color = <LED_COLOR_ID_GREEN>;
> +			max-brightness = <255>;
> +			label = "d4";
> +		};
> +	};
>  };
>
>  &uart0 {