edt_ft5x06.dts

/*
  EDT-FT5x06 touchscreen device tree for RPi B+/2/3

  Used GPIO pins (in BCM numbering):
    2 - SDA, 3 - SCL,
    5 - INT, 6 - WAKE
  RST is not populated, so not here
*/

/* Compile tool: `apt-get install flex bison && git clone git://git.kernel.org/pub/scm/utils/dtc/dtc.git` */
/* Compile command: https://github.com/notro/fbtft/wiki/FBTFT-RPI-overlays */

/dts-v1/;
/plugin/;

/ {
	compatible = "brcm,bcm2835", "brcm,bcm2708", "brcm,bcm2709"; /* ??? */

	fragment@0 {
		target = <&gpio>;

		__overlay__ {
			edt_ft5x06_pins: edt_ft5x06_pins {
				brcm,pins = <5 6>;
				brcm,function = <0 1>; /* in out */
			};
		};
	};

	fragment@1 {
		target = <&i2c_arm>; /* Same thing as &i2c1, BCM pin 2&3 */

		__overlay__ {
			/* Needed to avoid dtc warning */
			#address-cells = <1>;
			#size-cells = <0>;

			/* This makes "dtparam=i2c_arm=on" and/or "dtparam=i2c1=on" default */
			status = "okay";

			/* A workaround to fix `Unable to fetch data, error: -121` errors
			RPi's I2C implementation has a hardware bug which, on clock stretching, corrupts data.
			FT5x06's supported SCL frequency from datasheet is <= 400000, so maybe slowing it down works.
			See https://github.com/fivdi/i2c-bus/issues/36
			Default clock frequency value is 100000
			*/
			clock-frequency = <10000>;

			edt_ft5x06: touchscreen@38 {
				compatible = "edt,edt-ft5406", "edt,edt-ft5x06";
				status = "okay"; /* Opposite is "disabled" */

				reg = <0x38>;
				pinctrl-names = "default";
				pinctrl-0 = <&edt_ft5x06_pins>;
				interrupt-parent = <&gpio>;
				interrupts = <5 2>; /* IRQ_TYPE_EDGE_FALLING */
				wake-gpios = <&gpio 6 0>; /* GPIO_ACTIVE_HIGH */

				touchscreen-size-x = <800>;
				touchscreen-size-y = <480>;
				touchscreen-fuzz-x = <4>;
				touchscreen-fuzz-y = <7>;
				/* No pressure settings, or `DT specifies parameters but the axis 58 is not set up` */
			};
		};
	};

	__overrides__ {
		size-x =	<&edt_ft5x06>, "touchscreen-size-x:0";
		size-y =	<&edt_ft5x06>, "touchscreen-size-y:0";
		fuzz-x =	<&edt_ft5x06>, "touchscreen-fuzz-x:0";
		fuzz-y =	<&edt_ft5x06>, "touchscreen-fuzz-y:0";
		invert-x =	<&edt_ft5x06>, "touchscreen-inverted-x?";
		invert-y =	<&edt_ft5x06>, "touchscreen-inverted-y?";
		swap-xy =	<&edt_ft5x06>, "touchscreen-swapped-x-y?";
	};
};