Add GPIO backlight driver compatible with Linux FDT bindings.

Brightness is controlled through sysctl dev.gpiobacklight.X.brightness:
  - any value greater than 0: backlight is on
  - any value less than or equal to  0: backlight is off

FDT bindings docs in Linux tree:
    Documentation/devicetree/bindings/video/backlight/gpio-backlight.txt

1 files changed, 211 insertions, 0 deletions

diff --git a/sys/dev/gpio/gpiobacklight.c b/sys/dev/gpio/gpiobacklight.c
new file mode 100644
index 000000000000..3ff74f1e8969
--- /dev/null
+++ b/sys/dev/gpio/gpiobacklight.c
@@ -0,0 +1,211 @@
+/*-
+ * Copyright (c) 2015 Oleksandr Tymoshenko <gonzo@freebsd.org>
+ * All rights reserved.
+ *
+ * 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.
+ */
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include "opt_platform.h"
+
+#include <sys/param.h>
+#include <sys/systm.h>
+#include <sys/bus.h>
+#include <sys/gpio.h>
+#include <sys/kernel.h>
+#include <sys/lock.h>
+#include <sys/malloc.h>
+#include <sys/module.h>
+#include <sys/mutex.h>
+#include <sys/sysctl.h>
+
+#include <dev/fdt/fdt_common.h>
+#include <dev/ofw/ofw_bus.h>
+
+#include <dev/gpio/gpiobusvar.h>
+
+#include "gpiobus_if.h"
+
+/*
+ * Only one pin for led
+ */
+#define	GPIOBL_PIN	0
+
+#define GPIOBL_LOCK(_sc)		mtx_lock(&(_sc)->sc_mtx)
+#define	GPIOBL_UNLOCK(_sc)		mtx_unlock(&(_sc)->sc_mtx)
+#define GPIOBL_LOCK_INIT(_sc) \
+	mtx_init(&_sc->sc_mtx, device_get_nameunit(_sc->sc_dev), \
+	    "gpiobacklight", MTX_DEF)
+#define GPIOBL_LOCK_DESTROY(_sc)	mtx_destroy(&_sc->sc_mtx);
+
+struct gpiobacklight_softc 
+{
+	device_t	sc_dev;
+	device_t	sc_busdev;
+	struct mtx	sc_mtx;
+
+	struct sysctl_oid	*sc_oid;
+	int		sc_brightness;
+};
+
+static int gpiobacklight_sysctl(SYSCTL_HANDLER_ARGS);
+static void gpiobacklight_update_brightness(struct gpiobacklight_softc *);
+static int gpiobacklight_probe(device_t);
+static int gpiobacklight_attach(device_t);
+static int gpiobacklight_detach(device_t);
+
+static void 
+gpiobacklight_update_brightness(struct gpiobacklight_softc *sc)
+{
+	int error;
+
+	GPIOBL_LOCK(sc);
+	error = GPIOBUS_ACQUIRE_BUS(sc->sc_busdev, sc->sc_dev,
+	    GPIOBUS_DONTWAIT);
+	if (error != 0) {
+		GPIOBL_UNLOCK(sc);
+		return;
+	}
+	error = GPIOBUS_PIN_SETFLAGS(sc->sc_busdev, sc->sc_dev,
+	    GPIOBL_PIN, GPIO_PIN_OUTPUT);
+	if (error == 0)
+		GPIOBUS_PIN_SET(sc->sc_busdev, sc->sc_dev, GPIOBL_PIN,
+		    sc->sc_brightness ? GPIO_PIN_HIGH : GPIO_PIN_LOW);
+	GPIOBUS_RELEASE_BUS(sc->sc_busdev, sc->sc_dev);
+	GPIOBL_UNLOCK(sc);
+}
+
+static int
+gpiobacklight_sysctl(SYSCTL_HANDLER_ARGS)
+{
+	struct gpiobacklight_softc *sc;
+	int error;
+	int brightness;
+
+	sc = (struct gpiobacklight_softc*)arg1;
+	brightness = sc->sc_brightness;
+	error = sysctl_handle_int(oidp, &brightness, 0, req);
+
+	if (error != 0 || req->newptr == NULL)
+		return (error);
+
+	if (brightness <= 0)
+		sc->sc_brightness = 0;
+	else
+		sc->sc_brightness = 1;
+
+	gpiobacklight_update_brightness(sc);
+
+	return (error);
+}
+
+static void
+gpiobacklight_identify(driver_t *driver, device_t bus)
+{
+	phandle_t node, root;
+
+	root = OF_finddevice("/");
+	if (root == 0)
+		return;
+	for (node = OF_child(root); node != 0; node = OF_peer(node)) {
+		if (!fdt_is_compatible_strict(node, "gpio-backlight"))
+			continue;
+		ofw_gpiobus_add_fdt_child(bus, driver->name, node);
+	}
+}
+
+static int
+gpiobacklight_probe(device_t dev)
+{
+
+	if (!ofw_bus_is_compatible(dev, "gpio-backlight"))
+		return (ENXIO);
+
+	device_set_desc(dev, "GPIO backlight");
+
+	return (0);
+}
+
+static int
+gpiobacklight_attach(device_t dev)
+{
+	struct gpiobacklight_softc *sc;
+	struct sysctl_ctx_list *ctx;
+	struct sysctl_oid *tree;
+	phandle_t node;
+
+	sc = device_get_softc(dev);
+	sc->sc_dev = dev;
+	sc->sc_busdev = device_get_parent(dev);
+
+	if ((node = ofw_bus_get_node(dev)) == -1)
+		return (ENXIO);
+
+	GPIOBL_LOCK_INIT(sc);
+	if (OF_hasprop(node, "default-on"))
+		sc->sc_brightness = 1;
+	else
+		sc->sc_brightness = 0;
+
+	/* Init backlight interface */
+	ctx = device_get_sysctl_ctx(sc->sc_dev);
+	tree = device_get_sysctl_tree(sc->sc_dev);
+	sc->sc_oid = SYSCTL_ADD_PROC(ctx, SYSCTL_CHILDREN(tree), OID_AUTO,
+	    "brightness", CTLTYPE_INT | CTLFLAG_RW, sc, 0,
+	    gpiobacklight_sysctl, "I", "backlight brightness");
+
+	gpiobacklight_update_brightness(sc);
+
+	return (0);
+}
+
+static int
+gpiobacklight_detach(device_t dev)
+{
+	struct gpiobacklight_softc *sc;
+
+	sc = device_get_softc(dev);
+	GPIOBL_LOCK_DESTROY(sc);
+	return (0);
+}
+
+static devclass_t gpiobacklight_devclass;
+
+static device_method_t gpiobacklight_methods[] = {
+	/* Device interface */
+	DEVMETHOD(device_identify,	gpiobacklight_identify),
+	DEVMETHOD(device_probe,		gpiobacklight_probe),
+	DEVMETHOD(device_attach,	gpiobacklight_attach),
+	DEVMETHOD(device_detach,	gpiobacklight_detach),
+
+	DEVMETHOD_END
+};
+
+static driver_t gpiobacklight_driver = {
+	"gpiobacklight",
+	gpiobacklight_methods,
+	sizeof(struct gpiobacklight_softc),
+};
+
+DRIVER_MODULE(gpiobacklight, gpiobus, gpiobacklight_driver, gpiobacklight_devclass, 0, 0);