Pocket beagle EQEP

pb_eqep0.dts

/dts-v1/;
/plugin/;

#include <dt-bindings/gpio/gpio.h>
#include <dt-bindings/pinctrl/am33xx.h>
#include <dt-bindings/interrupt-controller/irq.h>

/ {
	/*
	 * Free up the pins used by the cape from the pinmux helpers.
	 */
	fragment@0 {
		target = <&ocp>;
		__overlay__ {
			P1_31_pinmux { status = "disabled"; }; // EQEP0A_in
			P2_34_pinmux { status = "disabled"; }; // EQEP0B_in
			// P2_28_pinmux { status = "disabled"; }; // EQEP0_index
			// P1_29_pinmux { status = "disabled"; }; // EQEP0_strobe

      // TODO/QUESTION: these seem to do nothing?
			cape-universal { status = "disabled"; };
			cape-universal@1 { status = "disabled"; };
		};
	};

	fragment@1 {
		target = <&eqep0>;
		__overlay__ {
			pinctrl-names = "default";
      // TODO: does not work: pinctrl-0 = <&pinctrl_eqep0>
			pinctrl-0 = <&P1_31_qep_pin &P2_34_qep_pin>;

			count_mode = <0>;	// count_mode is not userspace op_mode
			// 0 -> Quadrature mode, normal 90 phase offset cha & chb.
			// 1 -> Direction mode.  cha input = clock, chb input = direction
			// 2 -> UP count mode for frequency measurement QDIR=1, ignore direction input
			// 3 -> DOWN count mode for frequency measurement QDIR=0, ignore direction input

			swap_inputs = <0>; 	// swap channel A and B? (0 - no, 1 - yes)
			invert_qa = <0>;   	// invert channel A input?
			invert_qb = <0>;   	// invert channel B input?
			invert_qi = <0>;   	// invert index input?
			invert_qs = <0>;   	// invert strobe input?
			omit_interrupt = <0>;	// 1 -> do not install interrupt handler, 0 -> do install

			status = "okay";
		};
	};
};

pb_eqep2.dts

/dts-v1/;
/plugin/;

#include <dt-bindings/gpio/gpio.h>
#include <dt-bindings/pinctrl/am33xx.h>
#include <dt-bindings/interrupt-controller/irq.h>

/ {
	fragment@0 {
		target = <&ocp>;
		__overlay__ {
			P2_24_pinmux { status = "disabled"; }; // EQEP2A_in
			P2_33_pinmux { status = "disabled"; }; // EQEP2B_in
			// P2_18_pinmux { status = "disabled"; }; // EQEP2_strobe
			// P2_22_pinmux { status = "disabled"; }; // EQEP2_index
			cape-universal { status = "disabled"; };
			cape-universal@1 { status = "disabled"; };
		};
	};

	fragment@1 {
		target = <&eqep2>;
		__overlay__ {
			pinctrl-names = "default";
			pinctrl-0 = <&P2_24_qep_pin &P2_33_qep_pin>;

			count_mode = <0>;	// count_mode is not userspace op_mode
			// 0 -> Quadrature mode, normal 90 phase offset cha & chb.
			// 1 -> Direction mode.  cha input = clock, chb input = direction
			// 2 -> UP count mode for frequency measurement QDIR=1, ignore direction input
			// 3 -> DOWN count mode for frequency measurement QDIR=0, ignore direction input

			swap_inputs = <0>;	// swap channel A and B? (0 - no, 1 - yes)
			invert_qa = <0>;		// invert channel A input?
			invert_qb = <0>;		// invert channel B input?
			invert_qi = <0>;		// invert index input?
			invert_qs = <0>;		// invert strobe input?
			omit_interrupt = <0>;	// 1 -> do not install interrupt handler, 0 -> do install

			status = "okay";
		};
	};
};

These work with bone-debian-9.3-iot-armhf-2018-01-28-4gb.img (kernel 4.9.78-ti-r94).