stm32mp1: board: enable v1v2_hdmi and v3v3_hdmi regulator on dk2 boot

As for Audio codec IC, HDMI IC is not "IO safe".
HDMI regulators (v3v3 and v1v2) must be enabled to allow
I2C1 bus usage. HDMI IC must be under reset during power up
and keep HDMI and AUDIO devices in reset while they are not
used in U-Boot to keep them in low power mode
(each device can be kept in reset independently keeping their
power supplies ON until kernel).

Signed-off-by: Patrice Chotard <patrice.chotard@st.com>
Signed-off-by: Patrick Delaunay <patrick.delaunay@st.com>

3 files changed, 80 insertions, 0 deletions

diff --git a/arch/arm/dts/stm32mp157c-dk2-u-boot.dtsi b/arch/arm/dts/stm32mp157c-dk2-u-boot.dtsi
index 06ef3a4095..18ac1e3cb2 100644
--- a/arch/arm/dts/stm32mp157c-dk2-u-boot.dtsi
+++ b/arch/arm/dts/stm32mp157c-dk2-u-boot.dtsi
@@ -4,3 +4,9 @@
  */
 
 #include "stm32mp157a-dk1-u-boot.dtsi"
+
+&i2c1 {
+	hdmi-transmitter@39 {
+		reset-gpios = <&gpioa 10 GPIO_ACTIVE_LOW>;
+	};
+};
diff --git a/board/st/stm32mp1/Kconfig b/board/st/stm32mp1/Kconfig
index 87216c0963..4fa2360b4f 100644
--- a/board/st/stm32mp1/Kconfig
+++ b/board/st/stm32mp1/Kconfig
@@ -22,4 +22,8 @@ config CMD_STBOARD
 	  This compile the stboard command to
 	  read and write the board in the OTP.
 
+config TARGET_STM32MP157C_DK2
+	bool "support of STMicroelectronics STM32MP157C-DK2 Discovery Board"
+	default y
+
 endif
diff --git a/board/st/stm32mp1/stm32mp1.c b/board/st/stm32mp1/stm32mp1.c
index fdc4af3b64..e075f004b7 100644
--- a/board/st/stm32mp1/stm32mp1.c
+++ b/board/st/stm32mp1/stm32mp1.c
@@ -505,6 +505,73 @@ static void sysconf_init(void)
 #endif
 }
 
+#ifdef CONFIG_DM_REGULATOR
+/* Fix to make I2C1 usable on DK2 for touchscreen usage in kernel */
+static int dk2_i2c1_fix(void)
+{
+	ofnode node;
+	struct gpio_desc hdmi, audio;
+	int ret = 0;
+
+	node = ofnode_path("/soc/i2c@40012000/hdmi-transmitter@39");
+	if (!ofnode_valid(node)) {
+		pr_debug("%s: no hdmi-transmitter@39 ?\n", __func__);
+		return -ENOENT;
+	}
+
+	if (gpio_request_by_name_nodev(node, "reset-gpios", 0,
+				       &hdmi, GPIOD_IS_OUT)) {
+		pr_debug("%s: could not find reset-gpios\n",
+			 __func__);
+		return -ENOENT;
+	}
+
+	node = ofnode_path("/soc/i2c@40012000/cs42l51@4a");
+	if (!ofnode_valid(node)) {
+		pr_debug("%s: no cs42l51@4a ?\n", __func__);
+		return -ENOENT;
+	}
+
+	if (gpio_request_by_name_nodev(node, "reset-gpios", 0,
+				       &audio, GPIOD_IS_OUT)) {
+		pr_debug("%s: could not find reset-gpios\n",
+			 __func__);
+		return -ENOENT;
+	}
+
+	/* before power up, insure that HDMI and AUDIO IC is under reset */
+	ret = dm_gpio_set_value(&hdmi, 1);
+	if (ret) {
+		pr_err("%s: can't set_value for hdmi_nrst gpio", __func__);
+		goto error;
+	}
+	ret = dm_gpio_set_value(&audio, 1);
+	if (ret) {
+		pr_err("%s: can't set_value for audio_nrst gpio", __func__);
+		goto error;
+	}
+
+	/* power-up audio IC */
+	regulator_autoset_by_name("v1v8_audio", NULL);
+
+	/* power-up HDMI IC */
+	regulator_autoset_by_name("v1v2_hdmi", NULL);
+	regulator_autoset_by_name("v3v3_hdmi", NULL);
+
+error:
+	return ret;
+}
+
+static bool board_is_dk2(void)
+{
+	if (CONFIG_IS_ENABLED(TARGET_STM32MP157C_DK2) &&
+	    of_machine_is_compatible("st,stm32mp157c-dk2"))
+		return true;
+
+	return false;
+}
+#endif
+
 /* board dependent setup after realloc */
 int board_init(void)
 {
@@ -523,6 +590,9 @@ int board_init(void)
 	board_key_check();
 
 #ifdef CONFIG_DM_REGULATOR
+	if (board_is_dk2())
+		dk2_i2c1_fix();
+
 	regulators_enable_boot_on(_DEBUG);
 #endif