/* $NetBSD: meson_wdt.c,v 1.2 2021/01/27 03:10:18 thorpej Exp $ */

/*-
 * Copyright (c) 2019 Jared McNeill <jmcneill@invisible.ca>
 * 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/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: meson_wdt.c,v 1.2 2021/01/27 03:10:18 thorpej Exp $");

#include <sys/param.h>
#include <sys/bus.h>
#include <sys/cpu.h>
#include <sys/device.h>
#include <sys/wdog.h>

#include <dev/sysmon/sysmonvar.h>

#include <dev/fdt/fdtvar.h>

#define CBUS_REG(x)             ((x) << 2)

#define WATCHDOG_TC_REG         CBUS_REG(0)
#define  WATCHDOG_TC_CPUS       __BITS(27,24)
#define  WATCHDOG_TC_ENABLE     __BIT(19)
#define  WATCHDOG_TC_TCNT       __BITS(15,0)

#define WATCHDOG_RESET_REG      CBUS_REG(1)
#define  WATCHDOG_RESET_COUNT   __BITS(15,0)

#define WATCHDOG_PERIOD_DEFAULT         8
#define WATCHDOG_PERIOD_MAX             8
#define WATCHDOG_TICKS_PER_SEC          7812

static const struct device_compatible_entry compat_data[] = {
        { .compat = "amlogic,meson8b-wdt" },
        DEVICE_COMPAT_EOL
};

struct meson_wdt_softc {
        device_t                sc_dev;
        bus_space_tag_t         sc_bst;
        bus_space_handle_t      sc_bsh;

        struct sysmon_wdog      sc_wdog;
};

#define WDT_READ(sc, reg)               \
        bus_space_read_4((sc)->sc_bst, (sc)->sc_bsh, (reg))
#define WDT_WRITE(sc, reg, val) \
        bus_space_write_4((sc)->sc_bst, (sc)->sc_bsh, (reg), (val))

static int
meson_wdt_setmode(struct sysmon_wdog *smw)
{
        struct meson_wdt_softc * const sc = smw->smw_cookie;
        uint32_t val;

        if ((smw->smw_mode & WDOG_MODE_MASK) == WDOG_MODE_DISARMED) {
                WDT_WRITE(sc, WATCHDOG_RESET_REG, 0);
                val = WDT_READ(sc, WATCHDOG_TC_REG);
                val &= ~WATCHDOG_TC_ENABLE;
                WDT_WRITE(sc, WATCHDOG_TC_REG, val);
                return 0;
        }

        if (smw->smw_period == WDOG_PERIOD_DEFAULT) {
                sc->sc_wdog.smw_period = WATCHDOG_PERIOD_DEFAULT;
        } else if (smw->smw_period == 0 ||
                   smw->smw_period > WATCHDOG_PERIOD_MAX) {
                return EINVAL;
        } else {
                sc->sc_wdog.smw_period = smw->smw_period;
        }

        const u_int tcnt = sc->sc_wdog.smw_period * WATCHDOG_TICKS_PER_SEC;
        WDT_WRITE(sc, WATCHDOG_RESET_REG, 0);
        WDT_WRITE(sc, WATCHDOG_TC_REG, WATCHDOG_TC_CPUS | WATCHDOG_TC_ENABLE |
            __SHIFTIN(tcnt, WATCHDOG_TC_TCNT));

        return 0;
}

static int
meson_wdt_tickle(struct sysmon_wdog *smw)
{
        struct meson_wdt_softc * const sc = smw->smw_cookie;

        WDT_WRITE(sc, WATCHDOG_RESET_REG, 0);

        return 0;
}

static int
meson_wdt_match(device_t parent, cfdata_t cf, void *aux)
{
        struct fdt_attach_args * const faa = aux;

        return of_compatible_match(faa->faa_phandle, compat_data);
}

static void
meson_wdt_attach(device_t parent, device_t self, void *aux)
{
        struct meson_wdt_softc * const sc = device_private(self);
        struct fdt_attach_args * const faa = aux;
        const int phandle = faa->faa_phandle;
        bus_addr_t addr;
        bus_size_t size;
        uint32_t val;

        if (fdtbus_get_reg(phandle, 0, &addr, &size) != 0) {
                aprint_error(": couldn't get registers\n");
                return;
        }

        sc->sc_dev = self;
        sc->sc_bst = faa->faa_bst;
        if (bus_space_map(sc->sc_bst, addr, size, 0, &sc->sc_bsh) != 0) {
                aprint_error(": couldn't map registers\n");
                return;
        }

        aprint_naive("\n");
        aprint_normal(": EE-watchdog\n");

        /* Disable watchdog */
        WDT_WRITE(sc, WATCHDOG_RESET_REG, 0);
        val = WDT_READ(sc, WATCHDOG_TC_REG);
        val &= ~WATCHDOG_TC_ENABLE;
        WDT_WRITE(sc, WATCHDOG_TC_REG, val);

        /* Register watchdog */
        sc->sc_wdog.smw_name = "EE-watchdog";
        sc->sc_wdog.smw_setmode = meson_wdt_setmode;
        sc->sc_wdog.smw_tickle = meson_wdt_tickle;
        sc->sc_wdog.smw_period = WATCHDOG_PERIOD_DEFAULT;
        sc->sc_wdog.smw_cookie = sc;
        sysmon_wdog_register(&sc->sc_wdog);
}

CFATTACH_DECL_NEW(meson_wdt, sizeof(struct meson_wdt_softc),
    meson_wdt_match, meson_wdt_attach, NULL, NULL);