/* $OpenBSD: imxdog.c,v 1.4 2022/04/06 18:59:28 naddy Exp $ */
/*
 * Copyright (c) 2012-2013,2021 Patrick Wildt <patrick@blueri.se>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/device.h>
#include <sys/timeout.h>

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

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

extern void (*cpuresetfn)(void);

/* registers */
#define WCR             0x00
#define  WCR_WDE                (1 << 2)
#define  WCR_WT_SEC(x)          (((x) * 2 - 1) << 8)
#define  WCR_WT_MASK            (0xff << 8)
#define WSR             0x02
#define WRSR            0x04
#define WICR            0x06
#define WMCR            0x08

#define WDOG_TIMEOUT_CALLBACK           60
#define WDOG_MAX_TIMEOUT_SEC            128

struct imxdog_softc {
        struct device           sc_dev;
        bus_space_tag_t         sc_iot;
        bus_space_handle_t      sc_ioh;
        struct timeout          sc_tmo;
};

struct imxdog_softc *imxdog_sc;

int     imxdog_match(struct device *, void *, void *);
void    imxdog_attach(struct device *, struct device *, void *);
void    imxdog_reset(void);
void    imxdog_timeout(void *);

const struct cfattach imxdog_ca = {
        sizeof (struct imxdog_softc), imxdog_match, imxdog_attach
};

struct cfdriver imxdog_cd = {
        NULL, "imxdog", DV_DULL
};

int
imxdog_match(struct device *parent, void *match, void *aux)
{
        struct fdt_attach_args *faa = aux;

        return OF_is_compatible(faa->fa_node, "fsl,imx21-wdt");
}

void
imxdog_attach(struct device *parent, struct device *self, void *aux)
{
        struct fdt_attach_args *faa = aux;
        struct imxdog_softc *sc = (struct imxdog_softc *) self;
        uint16_t reg;

        if (faa->fa_nreg < 1)
                return;

        sc->sc_iot = faa->fa_iot;
        if (bus_space_map(sc->sc_iot, faa->fa_reg[0].addr,
            faa->fa_reg[0].size, 0, &sc->sc_ioh))
                panic("imxdog_attach: bus_space_map failed!");

        printf("\n");

        timeout_set(&sc->sc_tmo, imxdog_timeout, sc);

        /* Adjust timeout to maximum seconds */
        reg = bus_space_read_2(sc->sc_iot, sc->sc_ioh, WCR);
        reg &= ~WCR_WT_MASK;
        reg |= WCR_WT_SEC(WDOG_MAX_TIMEOUT_SEC);
        bus_space_write_2(sc->sc_iot, sc->sc_ioh, WCR, reg);

        /* Watchdog cannot be disabled, ping the watchdog if enabled */
        if (bus_space_read_2(sc->sc_iot, sc->sc_ioh, WCR) & WCR_WDE)
                imxdog_timeout(sc);

        imxdog_sc = sc;
        if (cpuresetfn == NULL)
                cpuresetfn = imxdog_reset;
}

void
imxdog_reset(void)
{
        struct imxdog_softc *sc = imxdog_sc;

        if (sc == NULL)
                return;

        /* disable watchdog and set timeout to 0 */
        bus_space_write_2(sc->sc_iot, sc->sc_ioh, WCR, 0);

        /* sequence to reset timeout counter */
        bus_space_write_2(sc->sc_iot, sc->sc_ioh, WSR, 0x5555);
        bus_space_write_2(sc->sc_iot, sc->sc_ioh, WSR, 0xaaaa);

        /* enable watchdog */
        bus_space_write_2(sc->sc_iot, sc->sc_ioh, WCR, 1);
        /* errata TKT039676 */
        bus_space_write_2(sc->sc_iot, sc->sc_ioh, WCR, 1);

        delay(100000);
}

void
imxdog_timeout(void *args)
{
        struct imxdog_softc *sc = args;

        /* Reload timeout counter */
        bus_space_write_2(sc->sc_iot, sc->sc_ioh, WSR, 0x5555);
        bus_space_write_2(sc->sc_iot, sc->sc_ioh, WSR, 0xaaaa);

        /* Schedule reload to trigger before counter runs out */
        timeout_add_sec(&sc->sc_tmo, WDOG_TIMEOUT_CALLBACK);
}