Move logic to change brightness level in reasonable steps from acpivout(4)

into wsdisplay(4).  This code is now exposed through
wsdisplay_brightness_{step,zero,cycle} functions that can be called by
any driver that handles brightnes "hotkeys".  These functions take
a wsdisplay(4) device pointer as their first argument, which should be
provided if a clear association between events and a particular display
exist.  This is used in wskbd(4).  Otherwise NULL can be passed and
the code will direct the request at the first wsdisplay(4) that
implements brightness adjustment.

Tested by many.  Fixes brightness keys on x395 and other thinkpads with
AMD graphics.

ok patrick@

3 files changed, 124 insertions, 6 deletions

diff --git a/sys/dev/wscons/wsdisplay.c b/sys/dev/wscons/wsdisplay.c
index 7bf8c016238..e0f16514133 100644
--- a/sys/dev/wscons/wsdisplay.c
+++ b/sys/dev/wscons/wsdisplay.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: wsdisplay.c,v 1.136 2020/03/22 07:59:59 anton Exp $ */
+/* $OpenBSD: wsdisplay.c,v 1.137 2020/04/19 15:05:14 kettenis Exp $ */
 /* $NetBSD: wsdisplay.c,v 1.82 2005/02/27 00:27:52 perry Exp $ */
 
 /*
@@ -2368,6 +2368,118 @@ wsdisplay_burner(void *v)
 }
 #endif
 
+int
+wsdisplay_get_param(struct wsdisplay_softc *sc, struct wsdisplay_param *dp)
+{
+	int error = ENXIO;
+	int i;
+
+	if (sc != NULL)
+		return wsdisplay_param(&sc->sc_dv, WSDISPLAYIO_GETPARAM, dp);
+
+	for (i = 0; i < wsdisplay_cd.cd_ndevs; i++) {
+		sc = wsdisplay_cd.cd_devs[i];
+		if (sc == NULL)
+			continue;
+		error = wsdisplay_param(&sc->sc_dv, WSDISPLAYIO_GETPARAM, dp);
+		if (error == 0)
+			break;
+	}
+
+	if (error && ws_get_param)
+		error = ws_get_param(dp);
+
+	return error;
+}
+
+int
+wsdisplay_set_param(struct wsdisplay_softc *sc, struct wsdisplay_param *dp)
+{
+	int error = ENXIO;
+	int i;
+
+	if (sc != NULL)
+		return wsdisplay_param(&sc->sc_dv, WSDISPLAYIO_SETPARAM, dp);
+
+	for (i = 0; i < wsdisplay_cd.cd_ndevs; i++) {
+		sc = wsdisplay_cd.cd_devs[i];
+		if (sc == NULL)
+			continue;
+		error = wsdisplay_param(&sc->sc_dv, WSDISPLAYIO_SETPARAM, dp);
+		if (error == 0)
+			break;
+	}
+
+	if (error && ws_set_param)
+		error = ws_set_param(dp);
+
+	return error;
+}
+
+void
+wsdisplay_brightness_step(struct device *dev, int dir)
+{
+	struct wsdisplay_softc *sc = (struct wsdisplay_softc *)dev;
+	struct wsdisplay_param dp;
+	int delta, new;
+
+	dp.param = WSDISPLAYIO_PARAM_BRIGHTNESS;
+	if (wsdisplay_get_param(sc, &dp))
+		return;
+
+	/* Use a step size of approximately 5%. */
+	delta = max(1, ((dp.max - dp.min) * 5) / 100);
+	new = dp.curval;
+
+	if (dir > 0) {
+		if (delta > dp.max - dp.curval)
+			new = dp.max;
+		else
+			new += delta;
+	} else if (dir < 0) {
+		if (delta > dp.curval - dp.min)
+			new = dp.min;
+		else
+			new -= delta;
+	}
+
+	if (dp.curval == new)
+		return;
+
+	dp.curval = new;
+	wsdisplay_set_param(sc, &dp);
+}
+
+void
+wsdisplay_brightness_zero(struct device *dev)
+{
+	struct wsdisplay_softc *sc = (struct wsdisplay_softc *)dev;
+	struct wsdisplay_param dp;
+
+	dp.param = WSDISPLAYIO_PARAM_BRIGHTNESS;
+	if (wsdisplay_get_param(sc, &dp))
+		return;
+
+	dp.curval = dp.min;
+	wsdisplay_set_param(sc, &dp);
+}
+
+void
+wsdisplay_brightness_cycle(struct device *dev)
+{
+	struct wsdisplay_softc *sc = (struct wsdisplay_softc *)dev;
+	struct wsdisplay_param dp;
+
+	dp.param = WSDISPLAYIO_PARAM_BRIGHTNESS;
+	if (wsdisplay_get_param(sc, &dp))
+		return;
+
+	if (dp.curval == dp.max)
+		wsdisplay_brightness_zero(dev);
+	else
+		wsdisplay_brightness_step(dev, 1);
+}
+
 #ifdef HAVE_WSMOUSED_SUPPORT
 /*
  * wsmoused(8) support functions
diff --git a/sys/dev/wscons/wsdisplayvar.h b/sys/dev/wscons/wsdisplayvar.h
index ee36ac26a08..170180a7363 100644
--- a/sys/dev/wscons/wsdisplayvar.h
+++ b/sys/dev/wscons/wsdisplayvar.h
@@ -1,4 +1,4 @@
-/* $OpenBSD: wsdisplayvar.h,v 1.34 2019/10/13 10:56:31 kettenis Exp $ */
+/* $OpenBSD: wsdisplayvar.h,v 1.35 2020/04/19 15:05:14 kettenis Exp $ */
 /* $NetBSD: wsdisplayvar.h,v 1.30 2005/02/04 02:10:49 perry Exp $ */
 
 /*
@@ -244,6 +244,10 @@ struct wsdisplay_param;
 extern int (*ws_get_param)(struct wsdisplay_param *);
 extern int (*ws_set_param)(struct wsdisplay_param *);
 
+void wsdisplay_brightness_step(struct device *, int);
+void wsdisplay_brightness_zero(struct device *);
+void wsdisplay_brightness_cycle(struct device *);
+
 /*
  * for use by wskbd
  */
diff --git a/sys/dev/wscons/wskbd.c b/sys/dev/wscons/wskbd.c
index e18173ab5c7..36680fab624 100644
--- a/sys/dev/wscons/wskbd.c
+++ b/sys/dev/wscons/wskbd.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: wskbd.c,v 1.103 2020/03/24 08:11:59 anton Exp $ */
+/* $OpenBSD: wskbd.c,v 1.104 2020/04/19 15:05:15 kettenis Exp $ */
 /* $NetBSD: wskbd.c,v 1.80 2005/05/04 01:52:16 augustss Exp $ */
 
 /*
@@ -1559,11 +1559,13 @@ internal_command(struct wskbd_softc *sc, u_int *type, keysym_t ksym,
 		    ksym == KS_Cmd_BacklightToggle ? 1 : 0);
 		return (1);
 	case KS_Cmd_BrightnessUp:
+		wsdisplay_brightness_step(sc->sc_displaydv, 1);
+		return (1);
 	case KS_Cmd_BrightnessDown:
+		wsdisplay_brightness_step(sc->sc_displaydv, -1);
+		return (1);
 	case KS_Cmd_BrightnessRotate:
-		change_displayparam(sc, WSDISPLAYIO_PARAM_BRIGHTNESS,
-		    ksym == KS_Cmd_BrightnessDown ? -1 : 1,
-		    ksym == KS_Cmd_BrightnessRotate ? 1 : 0);
+		wsdisplay_brightness_cycle(sc->sc_displaydv);
 		return (1);
 	case KS_Cmd_ContrastUp:
 	case KS_Cmd_ContrastDown: