/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2012, 2013 The FreeBSD Foundation
 *
 * This software was developed by Oleksandr Rybalko under sponsorship
 * from the FreeBSD Foundation.
 *
 * 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/resource.h>
#include <sys/rman.h>
#include <sys/systm.h>
#include <sys/time.h>
#include <sys/watchdog.h>

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

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

#include <arm/freescale/imx/imx_machdep.h>
#include <arm/freescale/imx/imx_wdogreg.h>

struct imx_wdog_softc {
        struct mtx              sc_mtx;
        device_t                sc_dev;
        struct resource         *sc_res[2];
        void                    *sc_ih;
        uint32_t                sc_timeout;
        bool                    sc_pde_enabled;
};

static struct resource_spec imx_wdog_spec[] = {
        { SYS_RES_MEMORY,       0,      RF_ACTIVE },
        { SYS_RES_IRQ,          0,      RF_ACTIVE },
        RESOURCE_SPEC_END
};

#define MEMRES  0
#define IRQRES  1

static struct ofw_compat_data compat_data[] = {
        {"fsl,imx6sx-wdt", 1},
        {"fsl,imx6sl-wdt", 1},
        {"fsl,imx6q-wdt",  1},
        {"fsl,imx53-wdt",  1},
        {"fsl,imx51-wdt",  1},
        {"fsl,imx50-wdt",  1},
        {"fsl,imx35-wdt",  1},
        {"fsl,imx27-wdt",  1},
        {"fsl,imx25-wdt",  1},
        {"fsl,imx21-wdt",  1},
        {NULL,             0}
};

static inline uint16_t
RD2(struct imx_wdog_softc *sc, bus_size_t offs)
{

        return (bus_read_2(sc->sc_res[MEMRES], offs));
}

static inline void
WR2(struct imx_wdog_softc *sc, bus_size_t offs, uint16_t val)
{

        bus_write_2(sc->sc_res[MEMRES], offs, val);
}

static int
imx_wdog_enable(struct imx_wdog_softc *sc, u_int timeout)
{
        uint16_t reg;

        if (timeout < 1 || timeout > 128)
                return (EINVAL);

        mtx_lock(&sc->sc_mtx);
        if (timeout != sc->sc_timeout) {
                sc->sc_timeout = timeout;
                reg = RD2(sc, WDOG_CR_REG);
                reg &= ~WDOG_CR_WT_MASK;
                reg |= ((2 * timeout - 1) << WDOG_CR_WT_SHIFT);
                WR2(sc, WDOG_CR_REG, reg | WDOG_CR_WDE);
        }
        /* Refresh counter */
        WR2(sc, WDOG_SR_REG, WDOG_SR_STEP1);
        WR2(sc, WDOG_SR_REG, WDOG_SR_STEP2);
        /* Watchdog active, can disable rom-boot watchdog. */
        if (sc->sc_pde_enabled) {
                sc->sc_pde_enabled = false;
                reg = RD2(sc, WDOG_MCR_REG);
                WR2(sc, WDOG_MCR_REG, reg & ~WDOG_MCR_PDE);
        }
        mtx_unlock(&sc->sc_mtx);

        return (0);
}

static void
imx_watchdog(void *arg, u_int cmd, int *error)
{
        struct imx_wdog_softc *sc;
        u_int timeout;

        sc = arg;
        if (cmd == 0) {
                if (bootverbose)
                        device_printf(sc->sc_dev, "Can not be disabled.\n");
                *error = EOPNOTSUPP;
        } else {
                timeout = (u_int)((1ULL << (cmd & WD_INTERVAL)) / 1000000000U);
                if (imx_wdog_enable(sc, timeout) == 0)
                        *error = 0;
        }
}

static int
imx_wdog_intr(void *arg)
{
        struct imx_wdog_softc *sc = arg;

        /*
         * When configured for external reset, the actual reset is supposed to
         * happen when some external device responds to the assertion of the
         * WDOG_B signal by asserting the POR signal to the chip.  This
         * interrupt handler is a backstop mechanism; it is set up to fire
         * simultaneously with WDOG_B, and if the external reset happens we'll
         * never actually make it to here.  If we do make it here, just trigger
         * a software reset.  That code will see that external reset is
         * configured, and it will wait for 1 second for it to take effect, then
         * it will do a software reset as a fallback.
         */
        imx_wdog_cpu_reset(BUS_SPACE_PHYSADDR(sc->sc_res[MEMRES], WDOG_CR_REG));

        return (FILTER_HANDLED); /* unreached */
}

static int
imx_wdog_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, "Freescale i.MX Watchdog");
        return (0);
}

static int
imx_wdog_attach(device_t dev)
{
        struct imx_wdog_softc *sc;
        pcell_t timeout;

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

        if (bus_alloc_resources(dev, imx_wdog_spec, sc->sc_res)) {
                device_printf(dev, "could not allocate resources\n");
                return (ENXIO);
        }

        mtx_init(&sc->sc_mtx, device_get_nameunit(dev), "imx_wdt", MTX_DEF);

        /*
         * If we're configured to assert an external reset signal, set up the
         * hardware to do so, and install an interrupt handler whose only
         * purpose is to backstop the external reset.  Don't worry if the
         * interrupt setup fails, since it's only a backstop measure.
         */
        if (ofw_bus_has_prop(sc->sc_dev, "fsl,ext-reset-output")) {
                WR2(sc, WDOG_CR_REG, WDOG_CR_WDT | RD2(sc, WDOG_CR_REG));
                bus_setup_intr(sc->sc_dev, sc->sc_res[IRQRES],
                    INTR_TYPE_MISC | INTR_MPSAFE, imx_wdog_intr, NULL, sc,
                    &sc->sc_ih);
                WR2(sc, WDOG_ICR_REG, WDOG_ICR_WIE); /* Enable, count is 0. */
        }

        /*
         * Note whether the rom-boot so-called "power-down" watchdog is active,
         * so we can disable it when the regular watchdog is first enabled.
         */
        if (RD2(sc, WDOG_MCR_REG) & WDOG_MCR_PDE)
                sc->sc_pde_enabled = true;

        EVENTHANDLER_REGISTER(watchdog_list, imx_watchdog, sc, 0);

        /* If there is a timeout-sec property, activate the watchdog. */
        if (OF_getencprop(ofw_bus_get_node(sc->sc_dev), "timeout-sec",
            &timeout, sizeof(timeout)) == sizeof(timeout)) {
                if (timeout < 1 || timeout > 128) {
                        device_printf(sc->sc_dev, "ERROR: bad timeout-sec "
                            "property value %u, using 128\n", timeout);
                        timeout = 128;
                }
                imx_wdog_enable(sc, timeout);
                device_printf(sc->sc_dev, "watchdog enabled using "
                    "timeout-sec property value %u\n", timeout);
        }

        /*
         * The watchdog hardware cannot be disabled, so there's little point in
         * coding up a detach() routine to carefully tear everything down, just
         * make the device busy so that detach can't happen.
         */
        device_busy(sc->sc_dev);
        return (0);
}

static device_method_t imx_wdog_methods[] = {
        DEVMETHOD(device_probe,         imx_wdog_probe),
        DEVMETHOD(device_attach,        imx_wdog_attach),
        DEVMETHOD_END
};

static driver_t imx_wdog_driver = {
        "imx_wdog",
        imx_wdog_methods,
        sizeof(struct imx_wdog_softc),
};

EARLY_DRIVER_MODULE(imx_wdog, simplebus, imx_wdog_driver, 0, 0, BUS_PASS_TIMER);
SIMPLEBUS_PNP_INFO(compat_data);