Add evdev support to TI ADC/touchscreen driver

Add generic evdev support to touchscreen part of ti_adc: two absolute
coordinates + button touch to indicate pen position. Pressure value
reporting is not implemented yet.

Tested on: Beaglebone Black + 4DCAPE-43T + tslib

sys/arm/conf/BEAGLEBONE

@@ -131,3 +131,6 @@ device		hdmi
 device		ums
 device		ukbd
 device		kbdmux
+
+# Uncomment to enable evdev support for ti_adc
+# options		EVDEV

sys/arm/ti/ti_adc.c

@@ -27,6 +27,8 @@
 #include <sys/cdefs.h>
 __FBSDID("$FreeBSD$");
 
+#include "opt_evdev.h"
+
 #include <sys/param.h>
 #include <sys/systm.h>
 #include <sys/bus.h>
@@ -52,6 +54,11 @@ __FBSDID("$FreeBSD$");
 #include <dev/ofw/ofw_bus.h>
 #include <dev/ofw/ofw_bus_subr.h>
 
+#ifdef EVDEV
+#include <dev/evdev/input.h>
+#include <dev/evdev/evdev.h>
+#endif
+
 #include <arm/ti/ti_prcm.h>
 #include <arm/ti/ti_adcreg.h>
 #include <arm/ti/ti_adcvar.h>
@@ -80,6 +87,41 @@ static struct ti_adc_input ti_adc_inputs[TI_ADC_NPINS] = {
 
 static int ti_adc_samples[5] = { 0, 2, 4, 8, 16 };
 
+static int ti_adc_detach(device_t dev);
+
+#ifdef EVDEV
+static evdev_open_t ti_adc_ev_open;
+static evdev_close_t ti_adc_ev_close;
+
+static struct evdev_methods ti_adc_evdev_methods = {
+	.ev_open = &ti_adc_ev_open,
+	.ev_close = &ti_adc_ev_close,
+};
+
+static void
+ti_adc_ev_close(struct evdev_dev *evdev, void *ev_softc)
+{
+	/* Nothing to do here */
+}
+
+static int
+ti_adc_ev_open(struct evdev_dev *evdev, void *ev_softc)
+{
+	/* Nothing to do here */
+	return (0);
+}
+
+static void
+ti_adc_ev_report(struct ti_adc_softc *sc)
+{
+
+	evdev_push_event(sc->sc_evdev, EV_ABS, ABS_X, sc->sc_x);
+	evdev_push_event(sc->sc_evdev, EV_ABS, ABS_Y, sc->sc_y);
+	evdev_push_event(sc->sc_evdev, EV_KEY, BTN_TOUCH, sc->sc_pen_down);
+	evdev_sync(sc->sc_evdev);
+}
+#endif /* EVDEV */
+
 static void
 ti_adc_enable(struct ti_adc_softc *sc)
 {
@@ -450,7 +492,14 @@ ti_adc_tsc_read_data(struct ti_adc_softc *sc)
 #ifdef DEBUG_TSC
 	device_printf(sc->sc_dev, "touchscreen x: %d, y: %d\n", x, y);
 #endif
-	/* TODO: That's where actual event reporting should take place */
+
+#ifdef EVDEV
+	if ((sc->sc_x != x) || (sc->sc_y != y)) {
+		sc->sc_x = x;
+		sc->sc_y = y;
+		ti_adc_ev_report(sc);
+	}
+#endif
 }
 
 static void
@@ -488,11 +537,17 @@ ti_adc_intr(void *arg)
 		status |= ADC_IRQ_HW_PEN_ASYNC;
 		ADC_WRITE4(sc, ADC_IRQENABLE_CLR,
 			ADC_IRQ_HW_PEN_ASYNC);
+#ifdef EVDEV
+		ti_adc_ev_report(sc);
+#endif
 	}
 
 	if (rawstatus & ADC_IRQ_PEN_UP) {
 		sc->sc_pen_down = 0;
 		status |= ADC_IRQ_PEN_UP;
+#ifdef EVDEV
+		ti_adc_ev_report(sc);
+#endif
 	}
 
 	if (status & ADC_IRQ_FIFO0_THRES)
@@ -840,6 +895,39 @@ ti_adc_attach(device_t dev)
 	ti_adc_setup(sc);
 	TI_ADC_UNLOCK(sc);
 
+#ifdef EVDEV
+	if (sc->sc_tsc_wires > 0) {
+		sc->sc_evdev = evdev_alloc();
+		evdev_set_name(sc->sc_evdev, device_get_desc(dev));
+		evdev_set_phys(sc->sc_evdev, device_get_nameunit(dev));
+		evdev_set_serial(sc->sc_evdev, "0");
+		evdev_set_methods(sc->sc_evdev, sc, &ti_adc_evdev_methods);
+		evdev_support_prop(sc->sc_evdev, INPUT_PROP_DIRECT);
+		evdev_support_event(sc->sc_evdev, EV_SYN);
+		evdev_support_event(sc->sc_evdev, EV_ABS);
+		evdev_support_event(sc->sc_evdev, EV_KEY);
+
+		evdev_support_abs(sc->sc_evdev, ABS_X, 0, 0,
+		    ADC_MAX_VALUE, 0, 0, 0);
+		evdev_support_abs(sc->sc_evdev, ABS_Y, 0, 0,
+		    ADC_MAX_VALUE, 0, 0, 0);
+
+		evdev_support_key(sc->sc_evdev, BTN_TOUCH);
+
+		err = evdev_register(sc->sc_evdev);
+		if (err) {
+			device_printf(dev,
+			    "failed to register evdev: error=%d\n", err);
+			ti_adc_detach(dev);
+			return (err);
+		}
+
+		sc->sc_pen_down = 0;
+		sc->sc_x = -1;
+		sc->sc_y = -1;
+	}
+#endif /* EVDEV */
+
 	return (0);
 }
 
@@ -854,6 +942,11 @@ ti_adc_detach(device_t dev)
 	TI_ADC_LOCK(sc);
 	ti_adc_reset(sc);
 	ti_adc_setup(sc);
+
+#ifdef EVDEV
+	evdev_free(sc->sc_evdev);
+#endif
+
 	TI_ADC_UNLOCK(sc);
 
 	TI_ADC_LOCK_DESTROY(sc);

sys/arm/ti/ti_adcreg.h

@@ -122,5 +122,6 @@
 #define	ADC_FIFO_STEP_ID_MSK		0x000f0000
 #define	ADC_FIFO_STEP_ID_SHIFT		16
 #define	ADC_FIFO_DATA_MSK		0x00000fff
+#define	ADC_MAX_VALUE		0xfff
 
 #endif /* _TI_ADCREG_H_ */

sys/arm/ti/ti_adcvar.h

@@ -55,6 +55,11 @@ struct ti_adc_softc {
 	int			sc_yn_bit, sc_yn_inp;
 	uint32_t		sc_tsc_enabled;
 	int			sc_pen_down;
+#ifdef EVDEV
+	int			sc_x;
+	int			sc_y;
+	struct evdev_dev *sc_evdev;
+#endif
 };
 
 struct ti_adc_input {