/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2011 Justin Hibbits
 * Copyright (c) 2009 Nathan Whitehorn
 * 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/param.h>
#include <sys/systm.h>
#include <sys/bus.h>
#include <sys/cpu.h>
#include <sys/kernel.h>
#include <sys/limits.h>
#include <sys/module.h>

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

#include "cpufreq_if.h"
#include "powerpc/powermac/pmuvar.h"

struct pmufreq_softc {
        device_t dev;
        uint32_t minfreq;
        uint32_t maxfreq;
        uint32_t curfreq;
};

static void     pmufreq_identify(driver_t *driver, device_t parent);
static int      pmufreq_probe(device_t dev);
static int      pmufreq_attach(device_t dev);
static int      pmufreq_settings(device_t dev, struct cf_setting *sets, int *count);
static int      pmufreq_set(device_t dev, const struct cf_setting *set);
static int      pmufreq_get(device_t dev, struct cf_setting *set);
static int      pmufreq_type(device_t dev, int *type);

static device_method_t pmufreq_methods[] = {
        /* Device interface */
        DEVMETHOD(device_identify,      pmufreq_identify),
        DEVMETHOD(device_probe,         pmufreq_probe),
        DEVMETHOD(device_attach,        pmufreq_attach),

        /* cpufreq interface */
        DEVMETHOD(cpufreq_drv_set,      pmufreq_set),
        DEVMETHOD(cpufreq_drv_get,      pmufreq_get),
        DEVMETHOD(cpufreq_drv_type,     pmufreq_type),
        DEVMETHOD(cpufreq_drv_settings, pmufreq_settings),
        {0, 0}
};

static driver_t pmufreq_driver = {
        "pmufreq",
        pmufreq_methods,
        sizeof(struct pmufreq_softc)
};

DRIVER_MODULE(pmufreq, cpu, pmufreq_driver, 0, 0);

static void
pmufreq_identify(driver_t *driver, device_t parent)
{
        phandle_t node;
        uint32_t min_freq;

        node = ofw_bus_get_node(parent);
        if (OF_getprop(node, "min-clock-frequency", &min_freq, sizeof(min_freq)) == -1)
                return;

        /* Make sure we're not being doubly invoked. */
        if (device_find_child(parent, "pmufreq", DEVICE_UNIT_ANY) != NULL)
                return;

        /*
         * We attach a child for every CPU since settings need to
         * be performed on every CPU in the SMP case.
         */
        if (BUS_ADD_CHILD(parent, 10, "pmufreq", DEVICE_UNIT_ANY) == NULL)
                device_printf(parent, "add pmufreq child failed\n");
}

static int
pmufreq_probe(device_t dev)
{
        phandle_t node;
        uint32_t min_freq;

        if (resource_disabled("pmufreq", 0))
                return (ENXIO);

        node = ofw_bus_get_node(device_get_parent(dev));
        /*
         * A scalable MPC7455 has min-clock-frequency/max-clock-frequency as OFW
         * properties of the 'cpu' node.
         */
        if (OF_getprop(node, "min-clock-frequency", &min_freq, sizeof(min_freq)) == -1)
                return (ENXIO);
        device_set_desc(dev, "PMU-based frequency scaling");
        return (0);
}

static int
pmufreq_attach(device_t dev)
{
        struct pmufreq_softc *sc;
        phandle_t node;

        sc = device_get_softc(dev);
        sc->dev = dev;

        node = ofw_bus_get_node(device_get_parent(dev));
        OF_getprop(node, "min-clock-frequency", &sc->minfreq, sizeof(sc->minfreq));
        OF_getprop(node, "max-clock-frequency", &sc->maxfreq, sizeof(sc->maxfreq));
        OF_getprop(node, "rounded-clock-frequency", &sc->curfreq, sizeof(sc->curfreq));
        sc->minfreq /= 1000000;
        sc->maxfreq /= 1000000;
        sc->curfreq /= 1000000;

        cpufreq_register(dev);
        return (0);
}

static int
pmufreq_settings(device_t dev, struct cf_setting *sets, int *count)
{
        struct pmufreq_softc *sc;

        sc = device_get_softc(dev);
        if (sets == NULL || count == NULL)
                return (EINVAL);
        if (*count < 2)
                return (E2BIG);

        /* Return a list of valid settings for this driver. */
        memset(sets, CPUFREQ_VAL_UNKNOWN, sizeof(*sets) * 2);

        sets[0].freq = sc->maxfreq; sets[0].dev = dev;
        sets[1].freq = sc->minfreq; sets[1].dev = dev;
        /* Set high latency for CPU frequency changes, it's a tedious process. */
        sets[0].lat = INT_MAX;
        sets[1].lat = INT_MAX;
        *count = 2;

        return (0);
}

static int
pmufreq_set(device_t dev, const struct cf_setting *set)
{
        struct pmufreq_softc *sc;
        int error, speed_sel;

        if (set == NULL)
                return (EINVAL);

        sc = device_get_softc(dev);

        if (set->freq == sc->maxfreq)
                speed_sel = 0;
        else
                speed_sel = 1;

        error = pmu_set_speed(speed_sel);
        if (error == 0)
                sc->curfreq = set->freq;

        return (error);
}

static int
pmufreq_get(device_t dev, struct cf_setting *set)
{
        struct pmufreq_softc *sc;

        if (set == NULL)
                return (EINVAL);
        sc = device_get_softc(dev);

        set->freq = sc->curfreq;
        set->dev = dev;

        return (0);
}

static int
pmufreq_type(device_t dev, int *type)
{

        if (type == NULL)
                return (EINVAL);

        *type = CPUFREQ_TYPE_ABSOLUTE;
        return (0);
}