/* $OpenBSD: imxdog.c,v 1.3 2021/05/28 13:08:37 patrick 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 *);

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);
}