Add a driver for the RouterBoard RB800 User LED

This may work on other RouterBoard PPC platforms, but I don't have any to test
with.

sys/conf/files.powerpc

@@ -134,6 +134,7 @@ powerpc/mambo/mambo.c		optional	mambo
 powerpc/mambo/mambo_console.c	optional	mambo
 powerpc/mambo/mambo_disk.c	optional	mambo
 powerpc/mikrotik/platform_rb.c	optional	mikrotik
+powerpc/mikrotik/rb_led.c	optional	mikrotik
 powerpc/mpc85xx/atpic.c		optional	mpc85xx isa
 powerpc/mpc85xx/ds1553_bus_fdt.c	optional	ds1553 fdt
 powerpc/mpc85xx/ds1553_core.c	optional	ds1553

sys/powerpc/mikrotik/rb_led.c

@@ -0,0 +1,149 @@
+/*-
+ * Copyright (c) 2017 Justin Hibbits
+ * 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 ``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 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 <sys/param.h>
+#include <sys/systm.h>
+#include <sys/module.h>
+#include <sys/bus.h>
+#include <sys/conf.h>
+#include <sys/kernel.h>
+
+#include <dev/ofw/ofw_bus.h>
+#include <dev/ofw/openfirm.h>
+#include <dev/led/led.h>
+
+#include "gpio_if.h"
+
+struct rbled_softc {
+	struct cdev	*sc_led;
+	device_t	 sc_gpio;
+	uint32_t	 sc_ledpin;
+};
+
+static int	rbled_probe(device_t);
+static int	rbled_attach(device_t);
+static int	rbled_detach(device_t);
+static void	rbled_toggle(void *, int);
+
+static device_method_t  rbled_methods[] = {
+	/* Device interface */
+	DEVMETHOD(device_probe,		rbled_probe),
+	DEVMETHOD(device_attach,	rbled_attach),
+        DEVMETHOD(device_detach,        rbled_detach),
+
+	DEVMETHOD_END
+};
+
+static driver_t rbled_driver = {
+	"rbled",
+	rbled_methods,
+	sizeof(struct rbled_softc),
+};
+
+static devclass_t rbled_devclass;
+
+DRIVER_MODULE(rbled, simplebus, rbled_driver, rbled_devclass, 0, 0);
+
+static int
+rbled_probe(device_t dev)
+{
+	phandle_t node;
+	const char *name;
+	cell_t gp[2];
+	char model[6];
+
+	node = ofw_bus_get_node(dev);
+
+	name = ofw_bus_get_name(dev);
+	if (name == NULL)
+		return (ENXIO);
+	if (strcmp(name, "led") != 0)
+		return (ENXIO);
+
+	if (OF_getprop(node, "user_led", gp, sizeof(gp)) <= 0)
+		return (ENXIO);
+
+	/* Check root model. */
+	node = OF_peer(0);
+	if (OF_getprop(node, "model", model, sizeof(model)) <= 0)
+		return (ENXIO);
+	if (strcmp(model, "RB800") != 0)
+		return (ENXIO);
+
+	device_set_desc(dev, "RouterBoard LED");
+	return (0);
+}
+
+static int
+rbled_attach(device_t dev)
+{
+	struct rbled_softc *sc;
+	phandle_t node;
+	cell_t gp[2];
+
+	sc = device_get_softc(dev);
+	node = ofw_bus_get_node(dev);
+
+	if (OF_getprop(node, "user_led", gp, sizeof(gp)) <= 0)
+		return (ENXIO);
+	
+	sc->sc_gpio = OF_device_from_xref(gp[0]);
+	if (sc->sc_gpio == NULL) {
+		device_printf(dev, "No GPIO resource found!\n");
+		return (ENXIO);
+	}
+	sc->sc_ledpin = gp[1];
+
+	sc->sc_led = led_create(rbled_toggle, sc, "user_led");
+
+	if (sc->sc_led == NULL)
+		return (ENXIO);
+
+	return (0);
+}
+
+static int
+rbled_detach(device_t dev)
+{
+	struct rbled_softc *sc;
+
+	sc = device_get_softc(dev);
+	led_destroy(sc->sc_led);
+
+	return (0);
+}
+
+static void
+rbled_toggle(void *priv, int onoff)
+{
+	struct rbled_softc *sc = priv;
+
+	GPIO_PIN_SET(sc->sc_gpio, sc->sc_ledpin, onoff);
+}