add panel driver for lxf p5100

Documentation/dt-bindings.md

@@ -278,3 +278,26 @@ lk1st on boot, you can use this driver.
 lk2nd doesn't implement a fully-fledged led subsystem. The only purpose for
 this driver is for debugging and the LED behavior consistancy between lk1st
 and lk2nd.
+
+### Fixed Regulator
+
+lk2nd supports the `regulator-fixed` node. This node follows upstream binding except
+that most properties are not supported. Currently only `gpios` are supported in lk2nd.
+
+```
+reg_bl {
+    compatible = "regulator-gpio";
+    gpios = <&tlmm 9 GPIO_ACTIVE_HIGH>;
+};
+```
+
+This driver is mainly for lk1st since no previous boot-loader is capable to
+turn on those regulator that is requied by the panel and backlight. 
+If your device panel and backlight requied some regulator to be turned on,
+you can use this driver.
+
+lk2nd doesn't implement a fully-fledged regulator subsystem. The only purpose for
+this driver is for turning on those regulator that is requied by the panel and backlight
+and the regulator behavior consistancy between lk1st and lk2nd.
+
+

lk2nd/device/dts/msm8909/apq8009-1gb-qrd-skue.dts

@@ -48,5 +48,15 @@
 				compatible = "lenovo,boe-nt35523b";
 			};
 		};
+
+		reg_bl {
+			compatible = "regulator-fixed";
+			gpios = <&tlmm 9 GPIO_ACTIVE_HIGH>;
+		};
+
+		reg_lcd_3v3 {
+			compatible = "regulator-fixed";
+			gpios = <&tlmm 24 GPIO_ACTIVE_HIGH>;
+		};
 	};
 };

lk2nd/device/dts/msm8909/msm8909-1gb-qrd-skue.dts

@@ -48,5 +48,15 @@
 				compatible = "lenovo,boe-nt35523b";
 			};
 		};
+
+		reg_bl {
+			compatible = "regulator-fixed";
+			gpios = <&tlmm 9 GPIO_ACTIVE_HIGH>;
+		};
+
+		reg_lcd_3v3 {
+			compatible = "regulator-fixed";
+			gpios = <&tlmm 24 GPIO_ACTIVE_HIGH>;
+		};
 	};
 };

lk2nd/device/regulator-fixed.c

@@ -0,0 +1,32 @@
+// SPDX-License-Identifier: BSD-3-Clause
+/* Copyright (c) 2025 exkc <[email protected]> */
+
+#include <debug.h>
+#include <libfdt.h>
+
+#include <lk2nd/hw/gpio.h>
+
+#include "device.h"
+
+static int lk2nd_regulator_init(const void *dtb, int node)
+{
+	int ret;
+
+	struct gpiol_desc desc;
+	dprintf(SPEW, " Initializing regulator-fixed for %s",
+			fdt_get_name(dtb, node, NULL));
+	ret = 	gpiol_get(dtb, node, NULL, &desc, GPIOL_FLAGS_OUT_ASSERTED);
+
+		if (ret) {
+			dprintf(CRITICAL, "regulator-gpio: Failed to get gpio for %s: %d\n",
+				fdt_get_name(dtb, node, NULL), ret);
+		}
+
+	dprintf(SPEW, " | label | gpio        | active_low |\n");
+	dprintf(SPEW, " | %5s | 0x%02x 0x%04x | %d          |\n",
+			fdt_get_name(dtb, node, NULL), desc.dev, desc.pin, desc.active_low);
+
+	return 0;
+}
+
+LK2ND_DEVICE_INIT("regulator-fixed", lk2nd_regulator_init);

lk2nd/device/rules.mk

@@ -19,6 +19,7 @@ OBJS += \
 	$(LOCAL_DIR)/panel.o \
 	$(LOCAL_DIR)/keys.o \
 	$(LOCAL_DIR)/leds.o \
+	$(LOCAL_DIR)/regulator-fixed.o \
 
 ifneq ($(LK2ND_COMPATIBLE),)
 DEFINES += LK2ND_COMPATIBLE="$(LK2ND_COMPATIBLE)"