Subject: Re: [PATCH v7 5/6] arm64: dts: marvell: armada-37xx: add device node for UART clock and use it

From: Gregory CLEMENT <[email-masked]>
Date: Wed, 13 Oct 2021 16:13:16 +0200

Hello Pali,

> This change defines DT node for UART clock "marvell,armada-3700-uart-clock"
> and use this UART clock as a base clock for all UART devices.
>
> Signed-off-by: Pali Rohár <[email-masked]>
>
> ---
> Changes in v6:
> * Do not disable uartclk by default
> * Rename node to clock-controller@12010
> ---
>  arch/arm64/boot/dts/marvell/armada-37xx.dtsi | 14 ++++++++++++--
>  1 file changed, 12 insertions(+), 2 deletions(-)
>
> diff --git a/arch/arm64/boot/dts/marvell/armada-37xx.dtsi b/arch/arm64/boot/dts/marvell/armada-37xx.dtsi
> index 9acc5d2b5a00..f9bfe73d8ec2 100644
> --- a/arch/arm64/boot/dts/marvell/armada-37xx.dtsi
> +++ b/arch/arm64/boot/dts/marvell/armada-37xx.dtsi
> @@ -132,10 +132,20 @@
>  				reg = <0x11500 0x40>;
>  			};
>  
> +			uartclk: clock-controller@12010 {
> +				compatible = "marvell,armada-3700-uart-clock";
> +				reg = <0x12010 0x4>, <0x12210 0x4>;
> +				clocks = <&tbg 0>, <&tbg 1>, <&tbg 2>,
> +					<&tbg 3>, <&xtalclk>;
> +				clock-names = "TBG-A-P", "TBG-B-P", "TBG-A-S",
> +					"TBG-B-S", "xtal";
> +				#clock-cells = <1>;
> +			};
> +
>  			uart0: serial@12000 {
>  				compatible = "marvell,armada-3700-uart";
>  				reg = <0x12000 0x18>;
> -				clocks = <&xtalclk>;
> +				clocks = <&uartclk 0>;

What happens if we have a new kernel using on old device tree ?

Gregory

>  				interrupts =
>  				<GIC_SPI 11 IRQ_TYPE_LEVEL_HIGH>,
>  				<GIC_SPI 12 IRQ_TYPE_LEVEL_HIGH>,
> @@ -147,7 +157,7 @@
>  			uart1: serial@12200 {
>  				compatible = "marvell,armada-3700-uart-ext";
>  				reg = <0x12200 0x30>;
> -				clocks = <&xtalclk>;
> +				clocks = <&uartclk 1>;
>  				interrupts =
>  				<GIC_SPI 30 IRQ_TYPE_EDGE_RISING>,
>  				<GIC_SPI 31 IRQ_TYPE_EDGE_RISING>;
> -- 
> 2.20.1
>

-- 
Gregory Clement, Bootlin
Embedded Linux and Kernel engineering
http://bootlin.com

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