Add pwm_backlight

Driver for pwm-backlight compatible device.

Relnotes:	yes
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D26252

sys/conf/files

@@ -2755,6 +2755,7 @@ dev/pwm/pwmbus.c		optional pwm | pwmbus
 dev/pwm/pwmbus_if.m		optional pwm | pwmbus
 dev/pwm/ofw_pwm.c		optional pwm fdt | pwmbus fdt
 dev/pwm/ofw_pwmbus.c		optional pwm fdt | pwmbus fdt
+dev/pwm/pwm_backlight.c		optional pwm pwm_backlight fdt
 dev/quicc/quicc_core.c		optional quicc
 dev/ral/rt2560.c		optional ral
 dev/ral/rt2661.c		optional ral

sys/dev/pwm/pwm_backlight.c

@@ -0,0 +1,311 @@
+/*-
+ * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
+ *
+ * Copyright (c) 2020 Emmanuel Vadot <manu@FreeBSD.org>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ *
+ * $FreeBSD$
+ */
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+
+#include <sys/param.h>
+#include <sys/systm.h>
+#include <sys/bio.h>
+#include <sys/bus.h>
+#include <sys/conf.h>
+#include <sys/endian.h>
+#include <sys/fcntl.h>
+#include <sys/ioccom.h>
+#include <sys/kernel.h>
+#include <sys/kthread.h>
+#include <sys/lock.h>
+#include <sys/malloc.h>
+#include <sys/module.h>
+#include <sys/mutex.h>
+#include <sys/priv.h>
+#include <sys/slicer.h>
+#include <sys/sysctl.h>
+#include <sys/time.h>
+
+#include <dev/ofw/ofw_bus.h>
+#include <dev/ofw/ofw_bus_subr.h>
+
+#include <dev/extres/regulator/regulator.h>
+
+#include <dev/backlight/backlight.h>
+
+#include <dev/pwm/ofw_pwm.h>
+
+#include "backlight_if.h"
+#include "pwmbus_if.h"
+
+struct pwm_backlight_softc {
+	device_t	pwmdev;
+	struct cdev	*cdev;
+
+	pwm_channel_t	channel;
+	uint32_t	*levels;
+	ssize_t		nlevels;
+	int		default_level;
+	ssize_t		current_level;
+
+	regulator_t	power_supply;
+	uint64_t	period;
+	uint64_t	duty;
+	bool		enabled;
+};
+
+static int pwm_backlight_find_level_per_percent(struct pwm_backlight_softc *sc, int percent);
+
+static struct ofw_compat_data compat_data[] = {
+	{ "pwm-backlight",	1 },
+	{ NULL,			0 }
+};
+
+static int
+pwm_backlight_probe(device_t dev)
+{
+
+	if (!ofw_bus_search_compatible(dev, compat_data)->ocd_data)
+		return (ENXIO);
+
+	device_set_desc(dev, "PWM Backlight");
+	return (BUS_PROBE_DEFAULT);
+}
+
+static int
+pwm_backlight_attach(device_t dev)
+{
+	struct pwm_backlight_softc *sc;
+	phandle_t node;
+	int rv;
+
+	sc = device_get_softc(dev);
+	node = ofw_bus_get_node(dev);
+
+	rv = pwm_get_by_ofw_propidx(dev, node, "pwms", 0, &sc->channel);
+	if (rv != 0) {
+		device_printf(dev, "Cannot map pwm channel %d\n", rv);
+		return (ENXIO);
+	}
+
+	if (regulator_get_by_ofw_property(dev, 0, "power-supply",
+	    &sc->power_supply) != 0) {
+		device_printf(dev, "No power-supply property\n");
+		return (ENXIO);
+	}
+
+	if (OF_hasprop(node, "brightness-levels")) {
+		sc->nlevels = OF_getencprop_alloc(node, "brightness-levels",
+		    (void **)&sc->levels);
+		if (sc->nlevels <= 0) {
+			device_printf(dev, "Cannot parse brightness levels\n");
+			return (ENXIO);
+		}
+		sc->nlevels /= sizeof(uint32_t);
+
+		if (OF_getencprop(node, "default-brightness-level",
+		    &sc->default_level, sizeof(uint32_t)) <= 0) {
+			device_printf(dev, "No default-brightness-level while brightness-levels is specified\n");
+			return (ENXIO);
+		} else {
+			if (sc->default_level > sc->nlevels) {
+				device_printf(dev, "default-brightness-level isn't present in brightness-levels range\n");
+				return (ENXIO);
+			}
+			sc->channel->duty = sc->channel->period * sc->levels[sc->default_level] / 100;
+		}
+
+		if (bootverbose) {
+			device_printf(dev, "Number of levels: %zd\n", sc->nlevels);
+			device_printf(dev, "Configured period time: %lu\n", sc->channel->period);
+			device_printf(dev, "Default duty cycle: %lu\n", sc->channel->duty);
+		}
+	} else {
+		/* Get the current backlight level */
+		PWMBUS_CHANNEL_GET_CONFIG(sc->channel->dev,
+		    sc->channel->channel,
+		    (unsigned int *)&sc->channel->period,
+		    (unsigned int *)&sc->channel->duty);
+		if (sc->channel->duty > sc->channel->period)
+			sc->channel->duty = sc->channel->period;
+		if (bootverbose) {
+			device_printf(dev, "Configured period time: %lu\n", sc->channel->period);
+			device_printf(dev, "Default duty cycle: %lu\n", sc->channel->duty);
+		}
+	}
+
+	regulator_enable(sc->power_supply);
+	sc->channel->enabled = true;
+	PWMBUS_CHANNEL_CONFIG(sc->channel->dev, sc->channel->channel,
+	    sc->channel->period, sc->channel->duty);
+	PWMBUS_CHANNEL_ENABLE(sc->channel->dev, sc->channel->channel,
+	    sc->channel->enabled);
+
+	sc->current_level = pwm_backlight_find_level_per_percent(sc,
+	    sc->channel->period / sc->channel->duty);
+	sc->cdev = backlight_register("pwm_backlight", dev);
+	if (sc->cdev == NULL)
+		device_printf(dev, "Cannot register as a backlight\n");
+
+	return (0);
+}
+
+static int
+pwm_backlight_detach(device_t dev)
+{
+	struct pwm_backlight_softc *sc;
+
+	sc = device_get_softc(dev);
+	if (sc->nlevels > 0)
+		OF_prop_free(sc->levels);
+	regulator_disable(sc->power_supply);
+	backlight_destroy(sc->cdev);
+	return (0);
+}
+
+static int
+pwm_backlight_find_level_per_percent(struct pwm_backlight_softc *sc, int percent)
+{
+	int i;
+	int diff;
+
+	if (percent < 0 || percent > 100)
+		return (-1);
+
+	for (i = 0, diff = 0; i < sc->nlevels; i++) {
+		if (sc->levels[i] == percent)
+			return (i);
+		else if (sc->levels[i] < percent)
+			diff = percent - sc->levels[i];
+		else {
+			if (diff < abs((percent - sc->levels[i])))
+				return (i - 1);
+			else
+				return (i);
+		}
+	}
+
+	return (-1);
+}
+
+static int
+pwm_backlight_update_status(device_t dev, struct backlight_props *props)
+{
+	struct pwm_backlight_softc *sc;
+	int reg_status;
+	int error;
+
+	sc = device_get_softc(dev);
+
+	if (sc->nlevels != 0) {
+		error = pwm_backlight_find_level_per_percent(sc,
+		    props->brightness);
+		if (error < 0)
+			return (ERANGE);
+		sc->current_level = error;
+		sc->channel->duty = sc->channel->period *
+			sc->levels[sc->current_level] / 100;
+	} else {
+		if (props->brightness > 100 || props->brightness < 0)
+			return (ERANGE);
+		sc->channel->duty = sc->channel->period *
+			props->brightness / 100;
+	}
+	sc->channel->enabled = true;
+	PWMBUS_CHANNEL_CONFIG(sc->channel->dev, sc->channel->channel,
+	    sc->channel->period, sc->channel->duty);
+	PWMBUS_CHANNEL_ENABLE(sc->channel->dev, sc->channel->channel,
+	    sc->channel->enabled);
+	error = regulator_status(sc->power_supply, &reg_status);
+	if (error != 0)
+		device_printf(dev,
+		    "Cannot get power-supply status: %d\n", error);
+	else {
+		if (props->brightness > 0) {
+			if (reg_status != REGULATOR_STATUS_ENABLED)
+				regulator_enable(sc->power_supply);
+		} else {
+			if (reg_status == REGULATOR_STATUS_ENABLED)
+				regulator_disable(sc->power_supply);
+		}
+	}
+
+	return (0);
+}
+
+static int
+pwm_backlight_get_status(device_t dev, struct backlight_props *props)
+{
+	struct pwm_backlight_softc *sc;
+	int i;
+
+	sc = device_get_softc(dev);
+
+	if (sc->nlevels != 0) {
+		props->brightness = sc->levels[sc->current_level];
+		props->nlevels = sc->nlevels;
+		for (i = 0; i < sc->nlevels; i++)
+			props->levels[i] = sc->levels[i];
+	} else {
+		props->brightness = sc->channel->duty * 100 / sc->channel->period;
+		props->nlevels = 0;
+	}
+	return (0);
+}
+
+static int
+pwm_backlight_get_info(device_t dev, struct backlight_info *info)
+{
+
+	info->type = BACKLIGHT_TYPE_PANEL;
+	strlcpy(info->name, "pwm-backlight", BACKLIGHTMAXNAMELENGTH);
+	return (0);
+}
+
+static device_method_t pwm_backlight_methods[] = {
+	/* device_if */
+	DEVMETHOD(device_probe, pwm_backlight_probe),
+	DEVMETHOD(device_attach, pwm_backlight_attach),
+	DEVMETHOD(device_detach, pwm_backlight_detach),
+
+	/* backlight interface */
+	DEVMETHOD(backlight_update_status, pwm_backlight_update_status),
+	DEVMETHOD(backlight_get_status, pwm_backlight_get_status),
+	DEVMETHOD(backlight_get_info, pwm_backlight_get_info),
+	DEVMETHOD_END
+};
+
+driver_t pwm_backlight_driver = {
+	"pwm_backlight",
+	pwm_backlight_methods,
+	sizeof(struct pwm_backlight_softc),
+};
+devclass_t pwm_backlight_devclass;
+
+DRIVER_MODULE(pwm_backlight, simplebus, pwm_backlight_driver,
+    pwm_backlight_devclass, 0, 0);
+OFWBUS_PNP_INFO(compat_data);

sys/modules/pwm/Makefile

@@ -5,5 +5,9 @@
 SUBDIR = \
 	pwmbus \
 	pwmc \
-	
+
+.if !empty(OPT_FDT)
+SUBDIR += pwm_backlight
+.endif
+
 .include <bsd.subdir.mk>

sys/modules/pwm/pwm_backlight/Makefile

@@ -0,0 +1,15 @@
+# $FreeBSD$
+
+.PATH:	${SRCTOP}/sys/dev/pwm
+KMOD=	pwm_backlight
+SRCS=	pwm_backlight.c
+
+SRCS+=	\
+	backlight_if.h \
+	bus_if.h \
+	device_if.h \
+	opt_platform.h \
+	pwmbus_if.h \
+	ofw_bus_if.h
+
+.include <bsd.kmod.mk>