From b5ec75dab38af2429278df48121642cb5605e318 Mon Sep 17 00:00:00 2001
From: Jasper Boomer <jasperboomer@gmail.com>
Date: Sun, 24 Jun 2018 12:20:27 -0400
Subject: [PATCH] Add device tree overlay for HD44780

---
 arch/arm/boot/dts/overlays/Makefile           |  1 +
 arch/arm/boot/dts/overlays/README             | 25 ++++++++++
 .../boot/dts/overlays/hd44780-lcd-overlay.dts | 46 +++++++++++++++++++
 3 files changed, 72 insertions(+)
 create mode 100644 arch/arm/boot/dts/overlays/hd44780-lcd-overlay.dts

--- a/arch/arm/boot/dts/overlays/Makefile
+++ b/arch/arm/boot/dts/overlays/Makefile
@@ -38,6 +38,7 @@ dtbo-$(CONFIG_ARCH_BCM2835) += \
 	gpio-no-irq.dtbo \
 	gpio-poweroff.dtbo \
 	gpio-shutdown.dtbo \
+	hd44780-lcd.dtbo \
 	hifiberry-amp.dtbo \
 	hifiberry-dac.dtbo \
 	hifiberry-dacplus.dtbo \
--- a/arch/arm/boot/dts/overlays/README
+++ b/arch/arm/boot/dts/overlays/README
@@ -639,6 +639,31 @@ Params: gpio_pin                GPIO pin
                                 external pullup.
 
 
+Name:   hd44780-lcd
+Info:   Configures an HD44780 compatible LCD display. Uses 4 gpio pins for
+        data, 2 gpio pins for enable and register select and 1 optional pin
+        for enabling/disabling the backlight display.
+Load:   dtoverlay=hd44780-lcd,<param>=<val>
+Params: pin_d4                  GPIO pin for data pin D4 (default 6)
+
+        pin_d5                  GPIO pin for data pin D5 (default 13)
+
+        pin_d6                  GPIO pin for data pin D6 (default 19)
+
+        pin_d7                  GPIO pin for data pin D7 (default 26)
+
+        pin_en                  GPIO pin for "Enable" (default 21)
+
+        pin_rs                  GPIO pin for "Register Select" (default 20)
+
+        pin_bl                  Optional pin for enabling/disabling the
+                                display backlight. (default disabled)
+
+        display_height          Height of the display in characters
+
+        display_width           Width of the display in characters
+
+
 Name:   hifiberry-amp
 Info:   Configures the HifiBerry Amp and Amp+ audio cards
 Load:   dtoverlay=hifiberry-amp
--- /dev/null
+++ b/arch/arm/boot/dts/overlays/hd44780-lcd-overlay.dts
@@ -0,0 +1,46 @@
+/dts-v1/;
+/plugin/;
+
+/ {
+    compatible = "brcm,bcm2835";
+
+    fragment@0 {
+        target-path = "/";
+        __overlay__ {
+            lcd_screen: auxdisplay {
+                compatible = "hit,hd44780";
+
+                data-gpios = <&gpio 6 0>,
+                             <&gpio 13 0>,
+                             <&gpio 19 0>,
+                             <&gpio 26 0>;
+                enable-gpios = <&gpio 21 0>;
+                rs-gpios = <&gpio 20 0>;
+
+                display-height-chars = <2>;
+                display-width-chars = <16>;
+            };
+
+        };
+    };
+
+    fragment@1 {
+       target = <&lcd_screen>;
+        __dormant__ {
+            backlight-gpios = <&gpio 12 0>;
+        };
+    };
+
+    __overrides__ {
+        pin_d4 = <&lcd_screen>,"data-gpios:4";
+        pin_d5 = <&lcd_screen>,"data-gpios:16";
+        pin_d6 = <&lcd_screen>,"data-gpios:28";
+        pin_d7 = <&lcd_screen>,"data-gpios:40";
+        pin_en = <&lcd_screen>,"enable-gpios:4";
+        pin_rs = <&lcd_screen>,"rs-gpios:4";
+        pin_bl = <0>,"+1", <&lcd_screen>,"backlight-gpios:4";
+        display_height = <&lcd_screen>,"display-height-chars:0";
+        display_width = <&lcd_screen>,"display-width-chars:0";
+    };
+
+};