/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2012 Alexander Rybalko <ray@freebsd.org>
 * 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 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/bus.h>
#include <sys/eventhandler.h>
#include <sys/kernel.h>
#include <sys/lock.h>
#include <sys/module.h>
#include <sys/mutex.h>
#include <sys/reboot.h>
#include <sys/rman.h>
#include <sys/systm.h>
#include <sys/watchdog.h>

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

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

#include <arm/broadcom/bcm2835/bcm2835_wdog.h>

#define BCM2835_PASSWORD        0x5a

#define BCM2835_WDOG_RESET      0
#define BCM2835_PASSWORD_MASK   0xff000000
#define BCM2835_PASSWORD_SHIFT  24
#define BCM2835_WDOG_TIME_MASK  0x000fffff
#define BCM2835_WDOG_TIME_SHIFT 0

#define READ(_sc, _r) bus_space_read_4((_sc)->bst, (_sc)->bsh, (_r) + (_sc)->regs_offset)
#define WRITE(_sc, _r, _v) bus_space_write_4((_sc)->bst, (_sc)->bsh, (_r) + (_sc)->regs_offset, (_v))

#define BCM2835_RSTC_WRCFG_CLR          0xffffffcf
#define BCM2835_RSTC_WRCFG_SET          0x00000030
#define BCM2835_RSTC_WRCFG_FULL_RESET   0x00000020
#define BCM2835_RSTC_RESET              0x00000102

#define BCM2835_RSTC_REG        0x00
#define BCM2835_RSTS_REG        0x04
#define BCM2835_WDOG_REG        0x08

static struct bcmwd_softc *bcmwd_lsc = NULL;

struct bcmwd_softc {
        device_t                dev;
        struct resource *       res;
        bus_space_tag_t         bst;
        bus_space_handle_t      bsh;
        int                     wdog_armed;
        int                     wdog_period;
        char                    wdog_passwd;
        struct mtx              mtx;
        int                     regs_offset;
};

#define BSD_DTB         1
#define UPSTREAM_DTB    2
#define UPSTREAM_DTB_REGS_OFFSET        0x1c

static struct ofw_compat_data compat_data[] = {
        {"broadcom,bcm2835-wdt",        BSD_DTB},
        {"brcm,bcm2835-pm-wdt",         UPSTREAM_DTB},
        {"brcm,bcm2835-pm",             UPSTREAM_DTB},
        {NULL,                          0}
};

static void bcmwd_watchdog_fn(void *private, u_int cmd, int *error);
static void bcmwd_reboot_system(void *, int);

static int
bcmwd_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, "BCM2708/2835 Watchdog");

        return (BUS_PROBE_DEFAULT);
}

static int
bcmwd_attach(device_t dev)
{
        struct bcmwd_softc *sc;
        int rid;

        if (bcmwd_lsc != NULL)
                return (ENXIO);

        sc = device_get_softc(dev);
        sc->wdog_period = 7;
        sc->wdog_passwd = BCM2835_PASSWORD;
        sc->wdog_armed = 0;
        sc->dev = dev;

        rid = 0;
        sc->res = bus_alloc_resource_any(dev, SYS_RES_MEMORY, &rid, RF_ACTIVE);
        if (sc->res == NULL) {
                device_printf(dev, "could not allocate memory resource\n");
                return (ENXIO);
        }

        sc->bst = rman_get_bustag(sc->res);
        sc->bsh = rman_get_bushandle(sc->res);

        /* compensate base address difference */
        if (ofw_bus_search_compatible(dev, compat_data)->ocd_data
           == UPSTREAM_DTB)
                sc->regs_offset = UPSTREAM_DTB_REGS_OFFSET;

        bcmwd_lsc = sc;
        mtx_init(&sc->mtx, "BCM2835 Watchdog", "bcmwd", MTX_DEF);
        EVENTHANDLER_REGISTER(watchdog_list, bcmwd_watchdog_fn, sc, 0);

        /*
         * Handle reboot events. This needs to happen with slightly greater
         * priority than the PSCI handler, since PSCI reset is not properly
         * implemented on the Pi and it just puts the Pi into a halt
         * state.
         */
        EVENTHANDLER_REGISTER(shutdown_final, bcmwd_reboot_system, sc,
            SHUTDOWN_PRI_LAST-1);

        return (0);
}

static void
bcmwd_watchdog_fn(void *private, u_int cmd, int *error)
{
        struct bcmwd_softc *sc;
        uint64_t sec;
        uint32_t ticks, reg;

        sc = private;
        mtx_lock(&sc->mtx);

        cmd &= WD_INTERVAL;

        if (cmd > 0) {
                sec = ((uint64_t)1 << (cmd & WD_INTERVAL)) / 1000000000;
                if (sec == 0 || sec > 15) {
                        /*
                         * Can't arm
                         * disable watchdog as watchdog(9) requires
                         */
                        device_printf(sc->dev,
                            "Can't arm, timeout must be between 1-15 seconds\n");
                        WRITE(sc, BCM2835_RSTC_REG,
                            (BCM2835_PASSWORD << BCM2835_PASSWORD_SHIFT) |
                            BCM2835_RSTC_RESET);
                        mtx_unlock(&sc->mtx);
                        *error = EINVAL;
                        return;
                }

                ticks = (sec << 16) & BCM2835_WDOG_TIME_MASK;
                reg = (BCM2835_PASSWORD << BCM2835_PASSWORD_SHIFT) | ticks;
                WRITE(sc, BCM2835_WDOG_REG, reg);

                reg = READ(sc, BCM2835_RSTC_REG);
                reg &= BCM2835_RSTC_WRCFG_CLR;
                reg |= BCM2835_RSTC_WRCFG_FULL_RESET;
                reg |= (BCM2835_PASSWORD << BCM2835_PASSWORD_SHIFT);
                WRITE(sc, BCM2835_RSTC_REG, reg);

                *error = 0;
        }
        else
                WRITE(sc, BCM2835_RSTC_REG,
                    (BCM2835_PASSWORD << BCM2835_PASSWORD_SHIFT) |
                    BCM2835_RSTC_RESET);

        mtx_unlock(&sc->mtx);
}

void
bcmwd_watchdog_reset(void)
{

        if (bcmwd_lsc == NULL)
                return;

        WRITE(bcmwd_lsc, BCM2835_WDOG_REG,
            (BCM2835_PASSWORD << BCM2835_PASSWORD_SHIFT) | 10);

        WRITE(bcmwd_lsc, BCM2835_RSTC_REG,
            (READ(bcmwd_lsc, BCM2835_RSTC_REG) & BCM2835_RSTC_WRCFG_CLR) |
                (BCM2835_PASSWORD << BCM2835_PASSWORD_SHIFT) |
                BCM2835_RSTC_WRCFG_FULL_RESET);
}

static void
bcmwd_reboot_system(void *sc, int howto)
{
        int cmd, error = 0;

        /* Only handle reset. */
        if (howto & RB_HALT || howto & RB_POWEROFF)
                return;

        printf("Resetting system ... ");

        cmd = WD_TO_1SEC;
        bcmwd_watchdog_fn(sc, cmd, &error);

        /* Wait for watchdog timeout. */
        DELAY(2000000);

        /* Not reached ... one hopes. */
        printf("failed to reset (errno %d).\n", error);
}

static device_method_t bcmwd_methods[] = {
        DEVMETHOD(device_probe, bcmwd_probe),
        DEVMETHOD(device_attach, bcmwd_attach),

        DEVMETHOD_END
};

static driver_t bcmwd_driver = {
        "bcmwd",
        bcmwd_methods,
        sizeof(struct bcmwd_softc),
};

DRIVER_MODULE(bcmwd, simplebus, bcmwd_driver, 0, 0);