[DO_NOT_MERGE PATCH v2 14/14] arm64: dts: ti: Add AM62L3 EVM overlay for GDEY042T81 e-paper display

[Devarsh Thakkar <devarsht@ti.com>]

Add device tree overlay for the Good Display GDEY042T81 4.2" e-paper
panel connected to the AM62L3 EVM via SPI.

The overlay configures SPI1 with the SSD1683-based GDEY042T81 panel
at 2MHz, with reset, busy, and DC GPIOs connected to MCU GPIO0.

Signed-off-by: Devarsh Thakkar <devarsht@ti.com>
---
Changes from v1:
  - No changes: Minor improvements to DTS overlay structure

NOTE: This should only be merged post driver is merged

 arch/arm64/boot/dts/ti/Makefile               |  6 ++
 .../ti/k3-am62l3-evm-epaper-gdey042t81.dtso   | 96 +++++++++++++++++++
 2 files changed, 102 insertions(+)
 create mode 100644 arch/arm64/boot/dts/ti/k3-am62l3-evm-epaper-gdey042t81.dtso

diff --git a/arch/arm64/boot/dts/ti/Makefile b/arch/arm64/boot/dts/ti/Makefile
index 795978e962ee..90e7a687ca86 100644
--- a/arch/arm64/boot/dts/ti/Makefile
+++ b/arch/arm64/boot/dts/ti/Makefile
@@ -82,6 +82,9 @@ dtb-$(CONFIG_ARCH_K3) += k3-am62d2-evm.dtb
 dtb-$(CONFIG_ARCH_K3) += k3-am62l3-beaglebadge.dtb
 dtb-$(CONFIG_ARCH_K3) += k3-am62l3-evm.dtb
 
+# Overlays for AM62Lx EVM
+dtb-$(CONFIG_ARCH_K3) += k3-am62l3-evm-epaper-gdey042t81.dtbo
+
 # Boards with AM62Px SoC
 dtb-$(CONFIG_ARCH_K3) += k3-am62p5-sk.dtb
 dtb-$(CONFIG_ARCH_K3) += k3-am62p5-var-som-symphony.dtb
@@ -319,6 +322,8 @@ k3-am62a7-sk-csi2-ov5640-dtbs := k3-am62a7-sk.dtb \
 k3-am62a7-sk-csi2-tevi-ov5640-dtbs := k3-am62a7-sk.dtb \
 	k3-am62x-sk-csi2-tevi-ov5640.dtbo
 k3-am62a7-sk-hdmi-audio-dtbs := k3-am62a7-sk.dtb k3-am62x-sk-hdmi-audio.dtbo
+k3-am62l3-evm-epaper-gdey042t81-dtbs := k3-am62l3-evm.dtb \
+	k3-am62l3-evm-epaper-gdey042t81.dtbo
 k3-am62p5-sk-csi2-imx219-dtbs := k3-am62p5-sk.dtb \
 	k3-am62x-sk-csi2-imx219.dtbo
 k3-am62p5-sk-csi2-ov5640-dtbs := k3-am62p5-sk.dtb \
@@ -458,6 +463,7 @@ dtb- += k3-am625-beagleplay-csi2-ov5640.dtb \
 	k3-am62a7-sk-csi2-imx219.dtb \
 	k3-am62a7-sk-csi2-ov5640.dtb \
 	k3-am62a7-sk-hdmi-audio.dtb \
+	k3-am62l3-evm-epaper-gdey042t81.dtb \
 	k3-am62p5-sk-csi2-imx219.dtb \
 	k3-am62p5-sk-csi2-ov5640.dtb \
 	k3-am62p5-sk-csi2-tevi-ov5640.dtb \
diff --git a/arch/arm64/boot/dts/ti/k3-am62l3-evm-epaper-gdey042t81.dtso b/arch/arm64/boot/dts/ti/k3-am62l3-evm-epaper-gdey042t81.dtso
new file mode 100644
index 000000000000..50975a2cdd2a
--- /dev/null
+++ b/arch/arm64/boot/dts/ti/k3-am62l3-evm-epaper-gdey042t81.dtso
@@ -0,0 +1,96 @@
+// SPDX-License-Identifier: GPL-2.0-only or MIT
+/*
+ * DT Overlay for GoodDisplay GDEY042T81 4.2" E-Paper Display on AM62L3 EVM
+ *
+ * The GDEY042T81 is a 400x300 black-and-white e-paper panel driven by a
+ * Solomon SSD1683 controller, connected via SPI1 on the AM62L3 EVM
+ * expansion header.
+ *
+ * Pin mapping (AM62L3 EVM expansion header):
+ * P5  --> BUSY  (GPMC0_AD0.GPIO0_31)
+ * P26 --> RST   (GPMC0_AD1.GPIO0_16)
+ * P27 --> CLK   (GPMC0_AD5.SPI1_CLK)
+ * P28 --> DC    (GPMC0_AD2.GPIO0_17)
+ * P29 --> DAT   (GPMC0_AD3.SPI1_D1 / MOSI)
+ * P30 --> CS    (GPMC0_AD4.SPI1_CS0)
+ *
+ * The GPMC0_AD[0:5] pins are multiplexed for SPI1 and GPIO use; GPMC0 is
+ * already disabled by default in the SoC DTSI.
+ *
+ * Copyright (C) 2025 Texas Instruments Incorporated - https://www.ti.com/
+ */
+
+/dts-v1/;
+/plugin/;
+
+#include <dt-bindings/gpio/gpio.h>
+#include "k3-pinctrl.h"
+
+&pmx0 {
+	dc_pins_default: epaper-dc-default-pins {
+		pinctrl-single,pins = <
+			AM62LX_IOPAD(0x0080, PIN_OUTPUT, 7) /* (K22) GPMC0_AD2.GPIO0_17 */
+		>;
+	};
+
+	rst_pins_default: epaper-rst-default-pins {
+		pinctrl-single,pins = <
+			AM62LX_IOPAD(0x007c, PIN_OUTPUT, 7) /* (L23) GPMC0_AD1.GPIO0_16 */
+		>;
+	};
+
+	busy_pins_default: epaper-busy-default-pins {
+		pinctrl-single,pins = <
+			AM62LX_IOPAD(0x00b8, PIN_INPUT, 7) /* (L21) GPMC0_AD0.GPIO0_31 */
+		>;
+	};
+
+	main_spi1_pins_default: main-spi1-default-pins {
+		pinctrl-single,pins = <
+			AM62LX_IOPAD(0x008c, PIN_OUTPUT, 4) /* (H22) GPMC0_AD5.SPI1_CLK */
+			AM62LX_IOPAD(0x0088, PIN_OUTPUT, 4) /* (K23) GPMC0_AD4.SPI1_CS0 */
+			AM62LX_IOPAD(0x0084, PIN_OUTPUT, 4) /* (J23) GPMC0_AD3.SPI1_D1  */
+		>;
+	};
+
+	fet_sel_pins_default: epaper-fet-sel-default-pins {
+		pinctrl-single,pins = <
+			AM62LX_IOPAD(0x01a8, PIN_OUTPUT, 7) /* (E13) SPI0_CLK.GPIO0_89 */
+		>;
+	};
+};
+
+/* Drive GPIO0_89 high to select the SPI1 path on the VOUT0 FET switch */
+&gpio0 {
+	fet-sel-hog {
+		gpio-hog;
+		gpios = <89 0>;
+		output-high;
+		line-name = "GPIO_EXP_CONN_FET_SEL";
+	};
+};
+
+&gpmc0 {
+	status = "disabled";
+};
+
+&spi1 {
+	#address-cells = <1>;
+	#size-cells = <0>;
+	pinctrl-names = "default";
+	pinctrl-0 = <&main_spi1_pins_default>, <&fet_sel_pins_default>;
+	status = "okay";
+
+	gdey042t81: display@0 {
+		compatible = "gooddisplay,gdey042t81", "solomon,ssd1683";
+		reg = <0>;
+		pinctrl-names = "default";
+		pinctrl-0 = <&dc_pins_default>,
+			    <&rst_pins_default>,
+			    <&busy_pins_default>;
+		spi-max-frequency = <2000000>;
+		reset-gpios = <&gpio0 16 GPIO_ACTIVE_LOW>;
+		dc-gpios    = <&gpio0 17 GPIO_ACTIVE_HIGH>;
+		busy-gpios  = <&gpio0 31 GPIO_ACTIVE_HIGH>;
+	};
+};
-- 
2.39.1