/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2020 Jessica Clarke <jrtc27@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.
 */

/*
 * Driver for simple syscon poweroff and reset devices. The device tree
 * specifications are fully described at:
 *
 * https://www.kernel.org/doc/Documentation/devicetree/bindings/power/reset/syscon-poweroff.txt
 * https://www.kernel.org/doc/Documentation/devicetree/bindings/power/reset/syscon-reboot.txt
 */

#include <sys/param.h>
#include <sys/bus.h>
#include <sys/types.h>
#include <sys/eventhandler.h>
#include <sys/kernel.h>
#include <sys/module.h>
#include <sys/reboot.h>

#include <machine/bus.h>

#include <dev/ofw/ofw_bus.h>
#include <dev/ofw/ofw_bus_subr.h>
#include <dev/ofw/openfirm.h>

#include "syscon_if.h"
#include "syscon.h"

struct syscon_power_softc {
        struct syscon           *regmap;
        uint32_t                offset;
        uint32_t                value;
        uint32_t                mask;
        bool                    reboot;
        eventhandler_tag        shutdown_tag;
};

static void
syscon_power_shutdown_final(device_t dev, int howto)
{
        struct syscon_power_softc *sc;
        bool write;

        sc = device_get_softc(dev);
        if (sc->reboot)
                write = (howto & RB_HALT) == 0;
        else
                write = (howto & RB_POWEROFF) != 0;

        if (write)
                SYSCON_MODIFY_4(sc->regmap, sc->offset, sc->mask,
                    sc->value & sc->mask);
}

static int
syscon_power_probe(device_t dev)
{

        if (!ofw_bus_status_okay(dev))
                return (ENXIO);

        if (ofw_bus_is_compatible(dev, "syscon-poweroff")) {
                device_set_desc(dev, "Syscon poweroff");
                return (BUS_PROBE_DEFAULT);
        } else if (ofw_bus_is_compatible(dev, "syscon-reboot")) {
                device_set_desc(dev, "Syscon reboot");
                return (BUS_PROBE_DEFAULT);
        }

        return (ENXIO);
}

static int
syscon_power_attach(device_t dev)
{
        struct syscon_power_softc *sc;
        phandle_t node;
        int error, len;
        bool has_mask;

        sc = device_get_softc(dev);
        node = ofw_bus_get_node(dev);

        if (!OF_hasprop(node, "regmap")) {
                device_printf(dev, "could not find regmap\n");
                return (ENXIO);
        }

        error = syscon_get_by_ofw_property(dev, node, "regmap", &sc->regmap);
        if (error != 0) {
                device_printf(dev, "could not get syscon\n");
                return (ENXIO);
        }

        len = OF_getproplen(node, "offset");
        if (len != 4) {
                device_printf(dev, "could not get offset\n");
                return (ENXIO);
        }

        OF_getencprop(node, "offset", &sc->offset, sizeof(sc->offset));

        /* Optional mask */
        has_mask = OF_hasprop(node, "mask");
        if (has_mask) {
                len = OF_getproplen(node, "mask");
                if (len != 4) {
                        device_printf(dev, "cannot handle mask\n");
                        return (ENXIO);
                }

                OF_getencprop(node, "mask", &sc->mask, sizeof(sc->mask));
        } else {
                sc->mask = 0xffffffff;
        }

        /*
         * From the device tree specification:
         *
         *   Legacy usage: If a node doesn't contain a value property but
         *   contains a mask property, the mask property is used as the value.
         */
        if (!OF_hasprop(node, "value")) {
                if (!has_mask) {
                        device_printf(dev, "must have a value or a mask\n");
                        return (ENXIO);
                }

                sc->value = sc->mask;
        } else {
                len = OF_getproplen(node, "value");
                if (len != 4) {
                        device_printf(dev, "cannot handle value\n");
                        return (ENXIO);
                }

                OF_getencprop(node, "value", &sc->value, sizeof(sc->value));
        }

        /* Handle reboot after shutdown_panic. */
        sc->reboot = ofw_bus_is_compatible(dev, "syscon-reboot");
        sc->shutdown_tag = EVENTHANDLER_REGISTER(shutdown_final,
            syscon_power_shutdown_final, dev,
            sc->reboot ? SHUTDOWN_PRI_LAST + 150 : SHUTDOWN_PRI_LAST);

        return (0);
}

static int
syscon_power_detach(device_t dev)
{
        struct syscon_power_softc *sc;

        sc = device_get_softc(dev);
        EVENTHANDLER_DEREGISTER(shutdown_final, sc->shutdown_tag);

        return (0);
}

static device_method_t syscon_power_methods[] = {
        DEVMETHOD(device_probe,         syscon_power_probe),
        DEVMETHOD(device_attach,        syscon_power_attach),
        DEVMETHOD(device_detach,        syscon_power_detach),

        DEVMETHOD_END
};

DEFINE_CLASS_0(syscon_power, syscon_power_driver, syscon_power_methods,
    sizeof(struct syscon_power_softc));

DRIVER_MODULE(syscon_power, simplebus, syscon_power_driver, NULL, NULL);