linux-kernel - Re: [PATCH 1/2] ARM: dts: bcm2*: Demux i2c0 with a pinctrl

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Message-ID: <1335ae03-705a-7a4a-a9ce-c6c55a2dcf34@i2se.com>
Date:   Wed, 9 Feb 2022 18:26:15 +0100
From:   Stefan Wahren <stefan.wahren@...e.com>
To:     Detlev Casanova <detlev.casanova@...labora.com>,
        linux-kernel@...r.kernel.org
Cc:     Arnd Bergmann <arnd@...db.de>, Olof Johansson <olof@...om.net>,
        "maintainer:ARM AND ARM64 SoC SUB-ARCHITECTURES (COMMON PARTS)" 
        <soc@...nel.org>, Rob Herring <robh+dt@...nel.org>,
        Nicolas Saenz Julienne <nsaenz@...nel.org>,
        Florian Fainelli <f.fainelli@...il.com>,
        Ray Jui <rjui@...adcom.com>,
        Scott Branden <sbranden@...adcom.com>,
        "maintainer:BROADCOM BCM281XX/BCM11XXX/BCM216XX ARM ARCHITE..." 
        <bcm-kernel-feedback-list@...adcom.com>,
        "moderated list:ARM AND ARM64 SoC SUB-ARCHITECTURES (COMMON PARTS)" 
        <linux-arm-kernel@...ts.infradead.org>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>,
        "moderated list:BROADCOM BCM2711/BCM2835 ARM ARCHITECTURE" 
        <linux-rpi-kernel@...ts.infradead.org>,
        Uwe Kleine-König <uwe@...ine-koenig.org>
Subject: Re: [PATCH 1/2] ARM: dts: bcm2*: Demux i2c0 with a pinctrl

Hi Detlev,

Am 09.02.22 um 17:25 schrieb Detlev Casanova:
> The i2c0 device has 2 different busses controlled by a pinctrl.
> This commit separates the device node into 2 i2c devices:
>  * pin 0: Base i2c bus
>  * pin 44: DSI i2c bus
>
> i2c0 is renamed to i2c0if so that device-trees referencing i2c0 don't
> break and use the i2c0 node defined in i2c0mux node.
>
> i2c_csi_dsi can be used to control devices via the DSI i2c bus, used for
> DSI displays.
>
> Signed-off-by: Detlev Casanova <detlev.casanova@...labora.com>

just a note: Uwe sends a similiar approach for the RTC on CM4 [1] which
hasn't applied yet.

[1] - https://www.spinics.net/lists/arm-kernel/msg944330.html

> ---
>  arch/arm/boot/dts/bcm2711-rpi-4-b.dts         |  1 +
>  arch/arm/boot/dts/bcm2711.dtsi                |  2 +-
>  arch/arm/boot/dts/bcm2835-rpi.dtsi            |  9 ++++---
>  .../boot/dts/bcm283x-rpi-i2c0mux_0_44.dtsi    |  4 +++
>  arch/arm/boot/dts/bcm283x.dtsi                | 26 ++++++++++++++++++-
>  5 files changed, 37 insertions(+), 5 deletions(-)
>  create mode 100644 arch/arm/boot/dts/bcm283x-rpi-i2c0mux_0_44.dtsi
>
> diff --git a/arch/arm/boot/dts/bcm2711-rpi-4-b.dts b/arch/arm/boot/dts/bcm2711-rpi-4-b.dts
> index 4432412044de..5dcce58817e6 100644
> --- a/arch/arm/boot/dts/bcm2711-rpi-4-b.dts
> +++ b/arch/arm/boot/dts/bcm2711-rpi-4-b.dts
> @@ -4,6 +4,7 @@
>  #include "bcm2711-rpi.dtsi"
>  #include "bcm283x-rpi-usb-peripheral.dtsi"
>  #include "bcm283x-rpi-wifi-bt.dtsi"
> +#include "bcm283x-rpi-i2c0mux_0_44.dtsi"
>  
>  / {
>  	compatible = "raspberrypi,4-model-b", "brcm,bcm2711";
> diff --git a/arch/arm/boot/dts/bcm2711.dtsi b/arch/arm/boot/dts/bcm2711.dtsi
> index 3b60297af7f6..bf6e8251c2c7 100644
> --- a/arch/arm/boot/dts/bcm2711.dtsi
> +++ b/arch/arm/boot/dts/bcm2711.dtsi
> @@ -1037,7 +1037,7 @@ &cma {
>  	alloc-ranges = <0x0 0x00000000 0x40000000>;
>  };
>  
> -&i2c0 {
> +&i2c0if {
>  	compatible = "brcm,bcm2711-i2c", "brcm,bcm2835-i2c";
>  	interrupts = <GIC_SPI 117 IRQ_TYPE_LEVEL_HIGH>;
>  };
> diff --git a/arch/arm/boot/dts/bcm2835-rpi.dtsi b/arch/arm/boot/dts/bcm2835-rpi.dtsi
> index 87ddcad76083..1e38f9f0e80e 100644
> --- a/arch/arm/boot/dts/bcm2835-rpi.dtsi
> +++ b/arch/arm/boot/dts/bcm2835-rpi.dtsi
> @@ -49,13 +49,16 @@ alt0: alt0 {
>  	};
>  };
>  
> -&i2c0 {
> -	pinctrl-names = "default";
> -	pinctrl-0 = <&i2c0_gpio0>;
> +&i2c0if {
>  	status = "okay";
>  	clock-frequency = <100000>;
>  };
>  
> +&i2c0mux {
> +	pinctrl-0 = <&i2c0_gpio0>;
> +	status = "okay";
> +};
> +
>  &i2c1 {
>  	pinctrl-names = "default";
>  	pinctrl-0 = <&i2c1_gpio2>;
> diff --git a/arch/arm/boot/dts/bcm283x-rpi-i2c0mux_0_44.dtsi b/arch/arm/boot/dts/bcm283x-rpi-i2c0mux_0_44.dtsi
> new file mode 100644
> index 000000000000..119946d878db
> --- /dev/null
> +++ b/arch/arm/boot/dts/bcm283x-rpi-i2c0mux_0_44.dtsi
> @@ -0,0 +1,4 @@
> +&i2c0mux {
> +	pinctrl-0 = <&i2c0_gpio0>;
> +	pinctrl-1 = <&i2c0_gpio44>;
> +};
> diff --git a/arch/arm/boot/dts/bcm283x.dtsi b/arch/arm/boot/dts/bcm283x.dtsi
> index a3e06b680947..06d04cde52b9 100644
> --- a/arch/arm/boot/dts/bcm283x.dtsi
> +++ b/arch/arm/boot/dts/bcm283x.dtsi
> @@ -334,7 +334,7 @@ spi: spi@...04000 {
>  			status = "disabled";
>  		};
>  
> -		i2c0: i2c@...05000 {
> +		i2c0if: i2c@...05000 {
>  			compatible = "brcm,bcm2835-i2c";
>  			reg = <0x7e205000 0x200>;
>  			interrupts = <2 21>;
> @@ -344,6 +344,30 @@ i2c0: i2c@...05000 {
>  			status = "disabled";
>  		};
>  
> +		i2c0mux: i2c0mux {
> +			compatible = "i2c-mux-pinctrl";
> +			#address-cells = <1>;
> +			#size-cells = <0>;
> +
> +			i2c-parent = <&i2c0if>;
> +
> +			pinctrl-names = "i2c0", "i2c_csi_dsi";
> +
> +			status = "disabled";
> +
> +			i2c0: i2c@0 {
> +				reg = <0>;
> +				#address-cells = <1>;
> +				#size-cells = <0>;
> +			};
> +
> +			i2c_csi_dsi: i2c@1 {
> +				reg = <1>;
> +				#address-cells = <1>;
> +				#size-cells = <0>;
> +			};
> +		};
> +
>  		dpi: dpi@...08000 {
>  			compatible = "brcm,bcm2835-dpi";
>  			reg = <0x7e208000 0x8c>;