linux-kernel - [RFC PATCH v2 1/3] ARM: dts: bcm2*: Demux i2c0 with a pinctrl

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Message-Id: <20220427185243.173594-2-detlev.casanova@collabora.com>
Date:   Wed, 27 Apr 2022 14:52:41 -0400
From:   Detlev Casanova <detlev.casanova@...labora.com>
To:     linux-kernel@...r.kernel.org
Cc:     arnd@...db.de, bcm-kernel-feedback-list@...adcom.com,
        devicetree@...r.kernel.org, f.fainelli@...il.com,
        frowand.list@...il.com, linux-arm-kernel@...ts.infradead.org,
        linux-rpi-kernel@...ts.infradead.org, masahiroy@...nel.org,
        michal.lkml@...kovi.net, ndesaulniers@...gle.com,
        nsaenz@...nel.org, olof@...om.net, rjui@...adcom.com,
        robh+dt@...nel.org, sbranden@...adcom.com, soc@...nel.org,
        stefan.wahren@...e.com,
        Detlev Casanova <detlev.casanova@...labora.com>
Subject: [RFC PATCH v2 1/3] ARM: dts: bcm2*: Demux i2c0 with a pinctrl

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>
---
 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 dff18fc9a906..96209ed89c36 100644
--- a/arch/arm/boot/dts/bcm2711.dtsi
+++ b/arch/arm/boot/dts/bcm2711.dtsi
@@ -1045,7 +1045,7 @@ &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 c113661a6668..62d7ee513549 100644
--- a/arch/arm/boot/dts/bcm283x.dtsi
+++ b/arch/arm/boot/dts/bcm283x.dtsi
@@ -336,7 +336,7 @@ spi: spi@...04000 {
 			status = "disabled";
 		};
 
-		i2c0: i2c@...05000 {
+		i2c0if: i2c@...05000 {
 			compatible = "brcm,bcm2835-i2c";
 			reg = <0x7e205000 0x200>;
 			interrupts = <2 21>;
@@ -346,6 +346,30 @@ 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>;
-- 
2.36.0