linux-kernel - Re: [PATCH] arm64: dts: qcom: db845c: Add support for MCP2517FD

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Date:   Mon, 18 Apr 2022 19:12:41 +0530
From:   Manivannan Sadhasivam <mani@...nel.org>
To:     Vinod Koul <vkoul@...nel.org>
Cc:     Bjorn Andersson <bjorn.andersson@...aro.org>,
        linux-arm-msm@...r.kernel.org, Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzk+dt@...nel.org>,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] arm64: dts: qcom: db845c: Add support for MCP2517FD

On Mon, Apr 18, 2022 at 06:28:41PM +0530, Vinod Koul wrote:
> Add support for onboard MCP2517FD SPI CAN transceiver attached to
> SPI0 of RB3.
> 
> Signed-off-by: Vinod Koul <vkoul@...nel.org>
> ---
>  arch/arm64/boot/dts/qcom/sdm845-db845c.dts | 23 ++++++++++++++++++++++
>  1 file changed, 23 insertions(+)
> 
> diff --git a/arch/arm64/boot/dts/qcom/sdm845-db845c.dts b/arch/arm64/boot/dts/qcom/sdm845-db845c.dts
> index 28fe45c5d516..5179f8ddb060 100644
> --- a/arch/arm64/boot/dts/qcom/sdm845-db845c.dts
> +++ b/arch/arm64/boot/dts/qcom/sdm845-db845c.dts
> @@ -28,6 +28,13 @@ chosen {
>  		stdout-path = "serial0:115200n8";
>  	};
>  
> +	/* Fixed crystal oscillator dedicated to MCP2517FD */
> +	clk40M: can_clock {
> +		compatible = "fixed-clock";
> +		#clock-cells = <0>;
> +		clock-frequency = <40000000>;
> +	};
> +
>  	dc12v: dc12v-regulator {
>  		compatible = "regulator-fixed";
>  		regulator-name = "DC12V";
> @@ -746,6 +753,22 @@ codec {
>  	};
>  };
>  
> +&spi0 {
> +	/* On Low speed expansion */

Only SPI2 is exposed on the LS header. This one is dedicated to CAN controller.

> +	status = "okay";

No chip select? Since CAN controller may operate at higher frequencies, it
makes sense to increase the drive strength of the pins.

Thanks,
Mani

> +
> +	can@0 {
> +		compatible = "microchip,mcp2517fd";
> +		reg = <0>;
> +		clocks = <&clk40M>;
> +		interrupts-extended = <&tlmm 104 IRQ_TYPE_LEVEL_LOW>;
> +		spi-max-frequency = <10000000>;
> +		vdd-supply = <&vdc_5v>;
> +		xceiver-supply = <&vdc_5v>;
> +		status = "okay";
> +	};
> +};
> +
>  &spi2 {
>  	/* On Low speed expansion */
>  	label = "LS-SPI0";
> -- 
> 2.34.1
>