[PATCH 2/2] board: gateworks: venice: poll I2C lines to wait for GSC firmware

[Tim Harvey <tharvey@gateworks.com>]

In some situations the GSC firmware where the EEPROM containing the
model and DRAM configuration may not be ready by the time the SoC
is ready to talk to it over I2C.

Instead of a hard delay, poll the I2C lines to wait until they are
released to avoid the I2C drivers 'Arbitation lost' error message.

Signed-off-by: Tim Harvey <tharvey@gateworks.com>
---
v2: move u-boot,dm-spl to *-u-boot.dtsi where it belongs
---
 arch/arm/dts/imx8mm-venice-u-boot.dtsi |  4 +++
 arch/arm/dts/imx8mm-venice.dts         | 12 +++++++-
 arch/arm/dts/imx8mn-venice-u-boot.dtsi |  4 +++
 arch/arm/dts/imx8mn-venice.dts         | 12 +++++++-
 arch/arm/dts/imx8mp-venice-u-boot.dtsi |  4 +++
 arch/arm/dts/imx8mp-venice.dts         | 12 +++++++-
 board/gateworks/venice/spl.c           | 39 +++++++++++++++++---------
 7 files changed, 70 insertions(+), 17 deletions(-)

diff --git a/arch/arm/dts/imx8mm-venice-u-boot.dtsi b/arch/arm/dts/imx8mm-venice-u-boot.dtsi
index 68978a0413ec..6f786b9467c2 100644
--- a/arch/arm/dts/imx8mm-venice-u-boot.dtsi
+++ b/arch/arm/dts/imx8mm-venice-u-boot.dtsi
@@ -57,6 +57,10 @@
 	u-boot,dm-spl;
 };
 
+&pinctrl_i2c1_gpio {
+	u-boot,dm-spl;
+};
+
 &gsc {
 	u-boot,dm-spl;
 };
diff --git a/arch/arm/dts/imx8mm-venice.dts b/arch/arm/dts/imx8mm-venice.dts
index 39b030691e53..d0929908ce84 100644
--- a/arch/arm/dts/imx8mm-venice.dts
+++ b/arch/arm/dts/imx8mm-venice.dts
@@ -23,8 +23,11 @@
 
 &i2c1 {
 	clock-frequency = <100000>;
-	pinctrl-names = "default";
+	pinctrl-names = "default", "gpio";
 	pinctrl-0 = <&pinctrl_i2c1>;
+	pinctrl-1 = <&pinctrl_i2c1_gpio>;
+	scl-gpios = <&gpio5 14 GPIO_ACTIVE_HIGH>;
+	sda-gpios = <&gpio5 15 GPIO_ACTIVE_HIGH>;
 	status = "okay";
 
 	gsc: gsc@20 {
@@ -89,6 +92,13 @@
 		>;
 	};
 
+	pinctrl_i2c1_gpio: i2c1grp-gpio-grp {
+		fsl,pins = <
+			MX8MM_IOMUXC_I2C1_SCL_GPIO5_IO14	0x400001c3
+			MX8MM_IOMUXC_I2C1_SDA_GPIO5_IO15	0x400001c3
+		>;
+	};
+
 	pinctrl_i2c2: i2c2grp {
 		fsl,pins = <
 			MX8MM_IOMUXC_I2C2_SCL_I2C2_SCL		0x400001c3
diff --git a/arch/arm/dts/imx8mn-venice-u-boot.dtsi b/arch/arm/dts/imx8mn-venice-u-boot.dtsi
index aea48f2d795b..4af6b8b4ed87 100644
--- a/arch/arm/dts/imx8mn-venice-u-boot.dtsi
+++ b/arch/arm/dts/imx8mn-venice-u-boot.dtsi
@@ -49,6 +49,10 @@
 	u-boot,dm-spl;
 };
 
+&pinctrl_i2c1_gpio {
+	u-boot,dm-spl;
+};
+
 &gsc {
 	u-boot,dm-spl;
 };
diff --git a/arch/arm/dts/imx8mn-venice.dts b/arch/arm/dts/imx8mn-venice.dts
index eeae225632d7..9e31b37f2496 100644
--- a/arch/arm/dts/imx8mn-venice.dts
+++ b/arch/arm/dts/imx8mn-venice.dts
@@ -23,8 +23,11 @@
 
 &i2c1 {
 	clock-frequency = <100000>;
-	pinctrl-names = "default";
+	pinctrl-names = "default", "gpio";
 	pinctrl-0 = <&pinctrl_i2c1>;
+	pinctrl-1 = <&pinctrl_i2c1_gpio>;
+	scl-gpios = <&gpio5 14 GPIO_ACTIVE_HIGH>;
+	sda-gpios = <&gpio5 15 GPIO_ACTIVE_HIGH>;
 	status = "okay";
 
 	gsc: gsc@20 {
@@ -89,6 +92,13 @@
 		>;
 	};
 
+	pinctrl_i2c1_gpio: i2c1grp-gpio-grp {
+		fsl,pins = <
+			MX8MN_IOMUXC_I2C1_SCL_GPIO5_IO14	0x400001c3
+			MX8MN_IOMUXC_I2C1_SDA_GPIO5_IO15	0x400001c3
+		>;
+	};
+
 	pinctrl_i2c2: i2c2grp {
 		fsl,pins = <
 			MX8MN_IOMUXC_I2C2_SCL_I2C2_SCL		0x400001c3
diff --git a/arch/arm/dts/imx8mp-venice-u-boot.dtsi b/arch/arm/dts/imx8mp-venice-u-boot.dtsi
index 96b9fa89cf46..f9068ebfbeea 100644
--- a/arch/arm/dts/imx8mp-venice-u-boot.dtsi
+++ b/arch/arm/dts/imx8mp-venice-u-boot.dtsi
@@ -57,6 +57,10 @@
 	u-boot,dm-spl;
 };
 
+&pinctrl_i2c1_gpio {
+	u-boot,dm-spl;
+};
+
 &gsc {
 	u-boot,dm-spl;
 };
diff --git a/arch/arm/dts/imx8mp-venice.dts b/arch/arm/dts/imx8mp-venice.dts
index 6b1a7f1a89d4..77e5ac423db3 100644
--- a/arch/arm/dts/imx8mp-venice.dts
+++ b/arch/arm/dts/imx8mp-venice.dts
@@ -23,8 +23,11 @@
 
 &i2c1 {
 	clock-frequency = <100000>;
-	pinctrl-names = "default";
+	pinctrl-names = "default", "gpio";
 	pinctrl-0 = <&pinctrl_i2c1>;
+	pinctrl-1 = <&pinctrl_i2c1_gpio>;
+	scl-gpios = <&gpio5 14 GPIO_ACTIVE_HIGH>;
+	sda-gpios = <&gpio5 15 GPIO_ACTIVE_HIGH>;
 	status = "okay";
 
 	gsc: gsc@20 {
@@ -89,6 +92,13 @@
 		>;
 	};
 
+	pinctrl_i2c1_gpio: i2c1grp-gpio-grp {
+		fsl,pins = <
+			MX8MP_IOMUXC_I2C1_SCL__GPIO5_IO14	0x400001c3
+			MX8MP_IOMUXC_I2C1_SDA__GPIO5_IO15	0x400001c3
+		>;
+	};
+
 	pinctrl_i2c2: i2c2grp {
 		fsl,pins = <
 			MX8MP_IOMUXC_I2C2_SCL__I2C2_SCL		0x400001c3
diff --git a/board/gateworks/venice/spl.c b/board/gateworks/venice/spl.c
index e06de8bb54c7..9d63f7db46d1 100644
--- a/board/gateworks/venice/spl.c
+++ b/board/gateworks/venice/spl.c
@@ -16,10 +16,12 @@
 #include <asm/arch/imx8mp_pins.h>
 #include <asm/arch/sys_proto.h>
 #include <asm/mach-imx/boot_mode.h>
+#include <asm/mach-imx/mxc_i2c.h>
 #include <asm/arch/ddr.h>
 #include <asm-generic/gpio.h>
 #include <dm/uclass.h>
 #include <dm/device.h>
+#include <dm/pinctrl.h>
 #include <linux/delay.h>
 #include <power/bd71837.h>
 #include <power/mp5416.h>
@@ -218,8 +220,8 @@ static int power_init_board(void)
 
 void board_init_f(ulong dummy)
 {
-	struct udevice *dev;
-	int ret;
+	struct udevice *bus, *dev;
+	int i, ret;
 	int dram_sz;
 
 	arch_cpu_init();
@@ -250,19 +252,28 @@ void board_init_f(ulong dummy)
 	 *
 	 * On a board with a missing/depleted backup battery for GSC, the
 	 * board may be ready to probe the GSC before its firmware is
-	 * running. We will wait here indefinately for the GSC EEPROM.
-	 */
-#ifdef CONFIG_IMX8MN
-	/*
-	 * IMX8MN boots quicker than IMX8MM and exposes issue
-	 * where because GSC I2C state machine isn't running and its
-	 * SCL/SDA are driven low the I2C driver spams 'Arbitration lost'
-	 * I2C errors.
-	 *
-	 * TODO: Put a loop here that somehow waits for I2C CLK/DAT to be high
+	 * running. Wait here for 50ms for the GSC firmware to let go of
+	 * the SCL/SDA lines to avoid the i2c driver spamming
+	 * 'Arbitration lost' I2C errors
 	 */
-	mdelay(50);
-#endif
+	if (!uclass_get_device_by_seq(UCLASS_I2C, 0, &bus)) {
+		if (!pinctrl_select_state(bus, "gpio")) {
+			struct mxc_i2c_bus *i2c_bus = dev_get_priv(bus);
+			struct gpio_desc *scl_gpio = &i2c_bus->scl_gpio;
+			struct gpio_desc *sda_gpio = &i2c_bus->sda_gpio;
+
+			dm_gpio_set_dir_flags(scl_gpio, GPIOD_IS_IN);
+			dm_gpio_set_dir_flags(sda_gpio, GPIOD_IS_IN);
+			for (i = 0; i < 5; i++) {
+				if (dm_gpio_get_value(scl_gpio) &&
+				    dm_gpio_get_value(sda_gpio))
+					break;
+				mdelay(10);
+			}
+			pinctrl_select_state(bus, "default");
+		}
+	}
+	/* Wait indefiniately until the GSC probes */
 	while (1) {
 		if (!uclass_get_device_by_driver(UCLASS_MISC, DM_DRIVER_GET(gsc), &dev))
 			break;
-- 
2.25.1