BBORG_DISPLAY18-00A2.txt

gistfile1.txt

/*
 * Copyright (C) 2013 CircuitCo
 * Copyright (C) 2018 Drew Fustini <drew@beagleboard.org>
 *
 * Adafruit 1.8" TFT LCD on SPI1 bus using tinydrm st7735r driver
 *
 * LICENSE:
 * --------
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * DOCUMENTATION:
 * --------------
 * This file was copied from src/arm/BB-SPIDEV1-00A0.dts and modified
 * by Drew Fustini based on an exmample from David Lechner.
 *
 * This is the Adafruit 1.8" TFT LCD:
 * https://www.adafruit.com/products/358
 *
 * It should be connected to BeagleBone SPI1 bus:
 *
 *   P9.12 <--> reset
 *   P9.14 <--> lite (pwm) [OPTIONAL]
 *   P9.15 <--> dc
 *   P9.23 <--> lite (gpio) [OPTIONAL]
 *   P9.28 <--> tft_cs
 *   P9.30 <--> mosi
 *   P9.31 <--> clk
 *
 * This overlay will load the mainline tinydrm st7735r driver by David Lechner:
 * https://github.com/torvalds/linux/blob/master/drivers/gpu/drm/tinydrm/st7735r.c
 *
 * Tested with 4.16.0-rc2-bone3 kernel on Debian 9.3 image
 *
 * Run libdrm modetest for colorbar test based on instructions from:
 * https://github.com/notro/tinydrm/wiki/Development#modetest
 *
 * modetest -M "st7735r" -c #this will display connector id
 * modetest -M "st7735r" -s 28:128x160 #connector id and resolution
 * # you should now see a color bar on the LCD
 *
 * Mailing list post with more information:
 * https://groups.google.com/d/msg/beagleboard/GuMQIP_XCW0/b3lxbx_8AwAJ
 *
 * GitHub Gist with testing results:
 * https://gist.github.com/pdp7/aee5664598059c9b9a9020f107957f80
 *
 * Discussion with notro on how to test tinydrm driver:
 * https://github.com/notro/tinydrm/issues/1#issuecomment-367279037
 */

#include <dt-bindings/gpio/gpio.h>
#include <dt-bindings/pinctrl/am33xx.h>
#include <dt-bindings/board/am335x-bbw-bbb-base.h>

/dts-v1/;
/plugin/;

/ {

	/*
	 * Free up the pins used by the cape from the pinmux helpers.
	 */
	fragment@0 {
		target = <&ocp>;
		__overlay__ {
			P8_35_pinmux { status = "disabled"; };	/* LEDs - 1 */
			P8_37_pinmux { status = "disabled"; };	/* LEDs - 2 */
			P9_17_pinmux { status = "disabled"; }; 	/* LCD - CS */
			P9_22_pinmux { status = "disabled"; };	/* LCD - SCLK */
			P9_18_pinmux { status = "disabled"; };	/* LCD - MOSI? */
			P9_21_pinmux { status = "disabled"; };	/* LCD - MISO? */
			P8_33_pinmux { status = "disabled"; };	/* LCD - DC */
			P8_31_pinmux { status = "disabled"; };	/* LCD - RST */
			P8_29_pinmux { status = "disabled"; };	/* button - 1 */
			P8_27_pinmux { status = "disabled"; };	/* button - 2 */
			P8_30_pinmux { status = "disabled"; };	/* button - 3 */
	 		P8_28_pinmux { status = "disabled"; };	/* button - 4 */
			P9_12_pinmux { status = "disabled"; };	/* button - 5 */
			P8_8_pinmux { status = "disabled"; };	/* button - 6 */
			P8_7_pinmux { status = "disabled"; };	/* button - 7 */
			P8_43_pinmux { status = "disabled"; };	/* button - 8 */
		};
	};

	fragment@1 {
		target = <&am33xx_pinmux>;
		__overlay__ {
			/* default state has all gpios released and mode set to uart1 */
			bb_spi1_pins: pinmux_bb_spi1_pins {
				pinctrl-single,pins = <
					0x190 0x33	/* mcasp0_aclkx.spi1_sclk, INPUT_PULLUP | MODE3 */
					0x194 0x33	/* mcasp0_fsx.spi1_d0, INPUT_PULLUP | MODE3 */
					0x198 0x13	/* mcasp0_axr0.spi1_d1, OUTPUT_PULLUP | MODE3 */
					0x19c 0x13	/* mcasp0_ahclkr.spi1_cs0, OUTPUT_PULLUP | MODE3 */
					// 0x164 0x12	/* eCAP0_in_PWM0_out.spi1_cs1 OUTPUT_PULLUP | MODE2 */
				>;
			};

			backlight_pwm_pins: pinmux_backlight_pwm_pins {
				pinctrl-single,pins = <
					BONE_P9_14 0x06 /* gpmc_a2.ehrpwm1a, OMAP_MUX_MODE6 | AM33XX_PIN_OUTPUT */
				>;
			};  /* gpmc_a2.ehrpwm1a */
		};
	};

	fragment@2 {
		target = <&epwmss1>;
		__overlay__ {
			status = "okay";
		};
	};

	fragment@3 {
		target = <&ehrpwm1>;
		__overlay__ {
			pinctrl-names = "default";
			pinctrl-0 = <&backlight_pwm_pins>;
			status = "okay";
		};
	};

	fragment@4 {
		target-path = "/";
		__overlay__ {

			bl_reg: backlight-regulator {
				compatible = "regulator-fixed";
				regulator-name = "backlight";
				regulator-always-on;
				regulator-boot-on;
			};

			/* backlight is optional */
			backlight_gpio: backlight_gpio {
				compatible = "gpio-backlight";
				gpios = <&gpio1 17 GPIO_ACTIVE_HIGH>;
				// connect lcd lite pin to P9.23 which is gpio1[17]
				// refer to https://elinux.org/Beagleboard:Cape_Expansion_Headers
			};

			/*
			 * Turn the PWM backlight on by setting bl_power to 0:
			 * echo 0 > /sys/devices/platform/backlight_pwm/backlight/backlight_pwm/bl_power
			 */
			backlight_pwm: backlight_pwm {
				// P9.14 <--> lite (pwm-backlight EHRPWM1A)
				status = "okay";
				compatible = "pwm-backlight";
				pwms = <&ehrpwm1 0 500000 0>;
				brightness-levels = <
					0  1  2  3  4  5  6  7  8  9
					10 11 12 13 14 15 16 17 18 19
					20 21 22 23 24 25 26 27 28 29
					30 31 32 33 34 35 36 37 38 39
					40 41 42 43 44 45 46 47 48 49
					50 51 52 53 54 55 56 57 58 59
					60 61 62 63 64 65 66 67 68 69
					70 71 72 73 74 75 76 77 78 79
					80 81 82 83 84 85 86 87 88 89
					90 91 92 93 94 95 96 97 98 99
					100
				>;
				default-brightness-level = <100>;
				power-supply = <&bl_reg>;
			};
		};
	};

	fragment@5 {
		target = <&spi0>;
		__overlay__ {
			#address-cells = <1>;
			#size-cells = <0>;

			status = "okay";
			pinctrl-names = "default";
			pinctrl-0 = <&bb_spi0_pins>;

			display@0{
				status = "okay";
				compatible = "jianda,jd-t18003-t01", "sitronix,st7735r";
				reg = <0>;
				spi-max-frequency = <16000000>;
				dc-gpios = <&gpio4 9 0>;      // lcd dc    P8.33 gpio4[9]
				reset-gpios = <&gpio4 10 0>;   // lcd reset P8.31 gpio4[10]
				// backlight is optional
				// choose either pwm or gpio control
				backlight = <&backlight_gpio>; // lcd lite  P8.9 gpio2[69]
				//backlight = <&backlight_pwm>;    // lcd lite  P9.14 gpmc_a2.ehrpwm1a
				// refer to https://elinux.org/Beagleboard:Cape_Expansion_Headers
				// rotation is optional
				// rotation = <270>;
			};
		};
	};
};