/*-
 * Copyright (c) 2012 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/bus.h>
#include <sys/systm.h>
#include <sys/module.h>
#include <sys/kernel.h>
#include <sys/rman.h>
#include <sys/sysctl.h>

#include <machine/bus.h>

#include <dev/ofw/openfirm.h>

#define NVIDIA_BRIGHT_MIN     (0x0ec)
#define NVIDIA_BRIGHT_MAX     (0x538)
#define NVIDIA_BRIGHT_SCALE   ((NVIDIA_BRIGHT_MAX - NVIDIA_BRIGHT_MIN)/100)
/* nVidia's MMIO registers are at PCI BAR[0] */
#define NVIDIA_MMIO_PMC       (0x0)
#define  NVIDIA_PMC_OFF         (NVIDIA_MMIO_PMC + 0x10f0)
#define   NVIDIA_PMC_BL_SHIFT    (16)
#define   NVIDIA_PMC_BL_EN       (1U << 31)


struct nvbl_softc {
	device_t	 dev;
	struct resource *sc_memr;
};

static void nvbl_identify(driver_t *driver, device_t parent);
static int nvbl_probe(device_t dev);
static int nvbl_attach(device_t dev);
static int nvbl_setlevel(struct nvbl_softc *sc, int newlevel);
static int nvbl_getlevel(struct nvbl_softc *sc);
static int nvbl_sysctl(SYSCTL_HANDLER_ARGS);

static device_method_t nvbl_methods[] = {
	/* Device interface */
	DEVMETHOD(device_identify, nvbl_identify),
	DEVMETHOD(device_probe, nvbl_probe),
	DEVMETHOD(device_attach, nvbl_attach),
	{0, 0},
};

static driver_t	nvbl_driver = {
	"backlight",
	nvbl_methods,
	sizeof(struct nvbl_softc)
};

static devclass_t nvbl_devclass;

DRIVER_MODULE(nvbl, vgapci, nvbl_driver, nvbl_devclass, 0, 0);

static void
nvbl_identify(driver_t *driver, device_t parent)
{
	if (OF_finddevice("mac-io/backlight") == -1)
		return;
	if (device_find_child(parent, "backlight", -1) == NULL)
		device_add_child(parent, "backlight", -1);
}

static int
nvbl_probe(device_t dev)
{
	char		control[8];
	phandle_t	handle;

	handle = OF_finddevice("mac-io/backlight");

	if (handle == -1)
		return (ENXIO);

	if (OF_getprop(handle, "backlight-control", &control, sizeof(control)) < 0)
		return (ENXIO);

	if (strcmp(control, "mnca") != 0)
		return (ENXIO);

	device_set_desc(dev, "PowerBook backlight for nVidia graphics");

	return (0);
}

static int
nvbl_attach(device_t dev)
{
	struct nvbl_softc	*sc;
	struct sysctl_ctx_list *ctx;
	struct sysctl_oid *tree;
	int			 rid;

	sc = device_get_softc(dev);

	rid = 0x10;	/* BAR[0], for the MMIO register */
	sc->sc_memr = bus_alloc_resource_any(dev, SYS_RES_MEMORY, &rid,
			RF_ACTIVE | RF_SHAREABLE);
	if (sc->sc_memr == NULL) {
		device_printf(dev, "Could not alloc mem resource!\n");
		return (ENXIO);
	}

	/* Turn on big-endian mode */
	if (!(bus_read_stream_4(sc->sc_memr, NVIDIA_MMIO_PMC + 4) & 0x01000001)) {
		bus_write_stream_4(sc->sc_memr, NVIDIA_MMIO_PMC + 4, 0x01000001);
		mb();
	}

	ctx = device_get_sysctl_ctx(dev);
	tree = device_get_sysctl_tree(dev);

	SYSCTL_ADD_PROC(ctx, SYSCTL_CHILDREN(tree), OID_AUTO,
			"level", CTLTYPE_INT | CTLFLAG_RW, sc, 0,
			nvbl_sysctl, "I", "Backlight level (0-100)");

	return (0);
}

static int
nvbl_setlevel(struct nvbl_softc *sc, int newlevel)
{
	uint32_t pmc_reg;

	if (newlevel > 100)
		newlevel = 100;

	if (newlevel < 0)
		newlevel = 0;

	if (newlevel > 0)
		newlevel = (newlevel * NVIDIA_BRIGHT_SCALE) + NVIDIA_BRIGHT_MIN;

	pmc_reg = bus_read_stream_4(sc->sc_memr, NVIDIA_PMC_OFF) & 0xffff;
	pmc_reg |= NVIDIA_PMC_BL_EN | (newlevel << NVIDIA_PMC_BL_SHIFT);
	bus_write_stream_4(sc->sc_memr, NVIDIA_PMC_OFF, pmc_reg);

	return (0);
}

static int
nvbl_getlevel(struct nvbl_softc *sc)
{
	uint16_t level;

	level = bus_read_stream_2(sc->sc_memr, NVIDIA_PMC_OFF) & 0x7fff;

	if (level  < NVIDIA_BRIGHT_MIN)
		return 0;

	level = (level - NVIDIA_BRIGHT_MIN) / NVIDIA_BRIGHT_SCALE;

	return (level);
}

static int
nvbl_sysctl(SYSCTL_HANDLER_ARGS)
{
	struct nvbl_softc *sc;
	int newlevel, error;

	sc = arg1;

	newlevel = nvbl_getlevel(sc);

	error = sysctl_handle_int(oidp, &newlevel, 0, req);

	if (error || !req->newptr)
		return (error);

	return (nvbl_setlevel(sc, newlevel));
}