[PATCH v2 2/2] arm: mvebu: x240: Use i2c-gpio instead of built in controller

[Chris Packham]

There is an Errata with the built-in I2C controller where various I2C
hardware errors cause a complete lockup of the CPU (which eventually
results in an watchdog reset).

Put the I2C MPP pins into GPIO mode and use the i2c-gpio driver instead.
This uses a bit-banged implementation of an I2C controller and avoids
triggering the Errata.

Signed-off-by: Chris Packham <judge.packham at gmail.com>
Reviewed-by: Stefan Roese <sr at denx.de>
---

Changes in v2:
- Update i2c0 alias
- Move i2c-gpio definition to root of device tree
- Remove &i2c0 instead of just disabling it
- Add r-by from Stefan

 arch/arm/dts/ac5-98dx35xx-atl-x240.dts | 30 ++++++++++++++++++++------
 configs/x240_defconfig                 |  1 +
 2 files changed, 24 insertions(+), 7 deletions(-)

diff --git a/arch/arm/dts/ac5-98dx35xx-atl-x240.dts b/arch/arm/dts/ac5-98dx35xx-atl-x240.dts
index 820ec18b4355..c19b25925ba2 100644
--- a/arch/arm/dts/ac5-98dx35xx-atl-x240.dts
+++ b/arch/arm/dts/ac5-98dx35xx-atl-x240.dts
@@ -16,7 +16,7 @@
 		gpio0 = &gpio0;
 		gpio1 = &gpio1;
 		spi0 = &spi0;
-		i2c0 = &i2c0;
+		i2c0 = &i2cgpio;
 		usb0 = &usb0;
 		pinctrl0 = &pinctrl0;
 	};
@@ -40,6 +40,19 @@
 			default-state = "on";
 		};
 	};
+
+	i2cgpio: i2c-gpio-0 {
+			compatible = "i2c-gpio";
+			#address-cells = <1>;
+			#size-cells = <0>;
+
+			pinctrl-names = "default";
+			pinctrl-0 =  <&i2c0_gpio>;
+			scl-gpios = <&gpio0 26 (GPIO_ACTIVE_HIGH | GPIO_OPEN_DRAIN)>;
+			sda-gpios = <&gpio0 27 (GPIO_ACTIVE_HIGH | GPIO_OPEN_DRAIN)>;
+			i2c-gpio,delay-us = <2>;
+			status = "okay";
+		 };
 };
 
 &nand {
@@ -70,9 +83,7 @@
 	status = "okay";
 };
 
-&i2c0 {
-	status = "okay";
-
+&i2cgpio {
 	mux at 71 {
 		#address-cells = <1>;
 		#size-cells = <0>;
@@ -177,8 +188,8 @@
 	 * LED_OE_N              [23]
 	 * USB_PWR_FLT_N         [24]
 	 * SFP_INT_N             [25]
-	 * I2C0_SCL              [26]
-	 * I2C0_SDA              [27]
+	 * I2C0_SCL              [26] (GPIO)
+	 * I2C0_SDA              [27] (GPIO)
 	 * USB_EN                [28]
 	 * MONITOR_INT_N         [29]
 	 * XM1_MDC               [30]
@@ -201,7 +212,7 @@
 	/*	     0    1    2    3    4    5    6    7    8    9 */
 	pin-func = < 0xff 0xff 0xff 0xff 0xff 0xff 0xff 0xff 0xff 0xff
 		     0xff 0xff 1    1    1    1    0xff 0xff 0    0
-		     0    0    0    0    0    0    1    1    0    0
+		     0    0    0    0    0    0    0xff 0xff 0    0
 		     1    1    1    1    0    0    0    0    0    0
 		     0    0    0    1    1    1    >;
 
@@ -209,4 +220,9 @@
 		marvell,pins = <0 1 2 3 4 5 6 7 8 9 10 11 16 17>;
 		marvell,function = <2>;
 	};
+
+	i2c0_gpio: i2c0-gpio-pins {
+		marvell,pins = <26 27>;
+		marvell,function = <0>;
+	};
 };
diff --git a/configs/x240_defconfig b/configs/x240_defconfig
index a78cb3ce6cbf..7d2b8603e6f4 100644
--- a/configs/x240_defconfig
+++ b/configs/x240_defconfig
@@ -42,6 +42,7 @@ CONFIG_CLK_MVEBU=y
 CONFIG_GPIO_HOG=y
 CONFIG_DM_PCA953X=y
 CONFIG_DM_I2C=y
+CONFIG_DM_I2C_GPIO=y
 CONFIG_SYS_I2C_MVTWSI=y
 CONFIG_I2C_MUX=y
 CONFIG_I2C_MUX_PCA954x=y
-- 
2.41.0