/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2024 Ruslan Bukin <br@bsdpad.com>
 *
 * 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/param.h>
#include <sys/systm.h>
#include <sys/bus.h>
#include <sys/kernel.h>
#include <sys/lock.h>
#include <sys/module.h>
#include <sys/mutex.h>

#include <machine/bus.h>
#include <machine/cpu.h>

#include <dev/syscon/syscon.h>
#include <dev/hwreset/hwreset.h>

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

#include "syscon_if.h"
#include "hwreset_if.h"

struct eswin_rst_softc {
        device_t                dev;
        struct mtx              mtx;
        struct syscon           *syscon;
};

#define RESET_BLOCK                     0x400
#define RESET_ID_TO_REG(x)              (RESET_BLOCK + (x) * 4)

#define ERST_LOCK(sc)                   mtx_lock(&(sc)->mtx)
#define ERST_UNLOCK(sc)                 mtx_unlock(&(sc)->mtx)
#define ERST_ASSERT_LOCKED(sc)          mtx_assert(&(sc)->mtx, MA_OWNED);
#define ERST_ASSERT_UNLOCKED(sc)        mtx_assert(&(sc)->mtx, MA_NOTOWNED);

#define ERST_READ(_sc, _reg)            \
    SYSCON_READ_4(sc->syscon, (_reg))
#define ERST_WRITE(_sc, _reg, _val)     \
    SYSCON_WRITE_4(sc->syscon, (_reg), (_val))

static struct ofw_compat_data compat_data[] = {
        { "eswin,eic7700-reset",        1 },
        { NULL,                         0 },
};

static int
eswin_rst_probe(device_t dev)
{

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

        if (ofw_bus_search_compatible(dev, compat_data)->ocd_data == 0)
                return (ENXIO);

        device_set_desc(dev, "Eswin Reset");

        return (BUS_PROBE_DEFAULT);
}

static int
eswin_rst_attach(device_t dev)
{
        struct eswin_rst_softc *sc;
        int error;

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

        error = syscon_get_by_ofw_node(dev, OF_parent(ofw_bus_get_node(dev)),
            &sc->syscon);
        if (error != 0) {
                device_printf(dev, "Couldn't get syscon handle of parent\n");
                return (error);
        }

        mtx_init(&sc->mtx, device_get_nameunit(sc->dev), NULL, MTX_DEF);

        hwreset_register_ofw_provider(dev);

        return (0);
}

static int
eswin_rst_reset_assert(device_t dev, intptr_t id, bool reset)
{
        struct eswin_rst_softc *sc;
        uint32_t reg;
        uint32_t base;
        uint32_t bit;

        sc = device_get_softc(dev);

        base = RESET_ID_TO_REG(id >> 5);
        bit = id & 0x1f;

        ERST_LOCK(sc);
        reg = ERST_READ(sc, base);
        if (reset)
                reg &= ~(1 << bit);
        else
                reg |= (1 << bit);
        ERST_WRITE(sc, base, reg);
        ERST_UNLOCK(sc);

        return (0);
}

static int
eswin_rst_reset_is_asserted(device_t dev, intptr_t id, bool *reset)
{
        struct eswin_rst_softc *sc;
        uint32_t reg;
        uint32_t base;
        uint32_t bit;

        sc = device_get_softc(dev);

        base = RESET_ID_TO_REG(id >> 5);
        bit = id & 0x1f;

        ERST_LOCK(sc);
        reg = ERST_READ(sc, base);
        *reset = (reg & (1 << bit)) == 0;
        ERST_UNLOCK(sc);

        return (0);
}

static int
eswin_rst_map(device_t provider_dev, phandle_t xref, int ncells,
    pcell_t *cells, intptr_t *id)
{

        KASSERT(ncells == 2, ("wrong ncells"));

        *id = cells[0] << 5;
        *id |= ilog2(cells[1]);

        return (0);
}

static device_method_t eswin_rst_methods[] = {
        /* Device interface. */
        DEVMETHOD(device_probe,         eswin_rst_probe),
        DEVMETHOD(device_attach,        eswin_rst_attach),

        /* Reset interface. */
        DEVMETHOD(hwreset_assert,       eswin_rst_reset_assert),
        DEVMETHOD(hwreset_is_asserted,  eswin_rst_reset_is_asserted),
        DEVMETHOD(hwreset_map,          eswin_rst_map),

        DEVMETHOD_END
};

static driver_t eswin_rst_driver = {
        "eswin_rst",
        eswin_rst_methods,
        sizeof(struct eswin_rst_softc)
};

EARLY_DRIVER_MODULE(eswin_rst, simplebus, eswin_rst_driver, 0, 0,
    BUS_PASS_BUS + BUS_PASS_ORDER_LATE);