// SPDX-License-Identifier: GPL-2.0+
/*
 * device tree overlay for the mhs-3.5 ads7846 resistive touch controller.
 *
 * fits in with `./mhs35-overlay.dts`!
 *
 * Copyright (c) 2026 Mel G. <mel@rnrd.eu>
 */

/dts-v1/;
/plugin/;

/ {
	compatible = "brcm,bcm2711";

	fragment@0 {
		target = <&spi0>;

		__overlay__ {
			status = "okay";

			spidev@1 {
				status = "disabled";
			};
		};
	};

	fragment@1 {
		target = <&gpio>;

		__overlay__ {
			mhs35_touch_pins: mhs35_touch_pins@0 {
				brcm,pins = <17>; // pen-irq
				brcm,function = <0>; // in
				brcm,pull = <2>; // up
			};
		};
	};

	fragment@2 {
		target = <&spi0>;

		__overlay__ {
			#address-cells = <1>;
			#size-cells = <0>;

			mhs35_touch: ads7846@1 {
				compatible = "ti,ads7846";
				reg = <1>;
				pinctrl-names = "default";
				pinctrl-0 = <&mhs35_touch_pins>;

				// adc should run at 2mhz as specced, anything
				// slower makes reading drift and drag weirdly!
				spi-max-frequency = <2000000>;
				interrupts = <17 2>; // falling edge
				interrupt-parent = <&gpio>;
				pendown-gpio = <&gpio 17 1>; // pen-irq, check pins!

				// these values try to supress garbage data on press,
				// without these, clicks are weird and unreliable!
				ti,keep-vref-on;
				ti,settle-delay-usec = /bits/ 16 <150>;
				ti,debounce-max = /bits/ 16 <10>;
				ti,debounce-tol = /bits/ 16 <30>;
				ti,debounce-rep = /bits/ 16 <1>;

				// NOTE(mel): these values do *not* calibrate the screenspace
				// coordination in accordance with the rotation by themselves!
				// the exact matrices are set via libinput in userspace.
				// see: `module.nix`
				ti,x-min = /bits/ 16 <200>;
				ti,y-min = /bits/ 16 <200>;
				ti,x-max = /bits/ 16 <3900>;
				ti,y-max = /bits/ 16 <3900>;
				// some basic pressure values provided by goodtft,
				// could be tuned maybe.
				ti,pressure-min = /bits/ 16 <0>;
				ti,pressure-max = /bits/ 16 <255>;
				ti,x-plate-ohms = /bits/ 16 <150>;
			};
		};
	};

	__overrides__ {
		touch_speed =  <&mhs35_touch>,"spi-max-frequency:0";
		touch_penirq = <&mhs35_touch_pins>,"brcm,pins:0",
			       <&mhs35_touch>,"interrupts:0",
			       <&mhs35_touch>,"pendown-gpio:4";
	};
};