/*      $NetBSD: gfrtc.c,v 1.7 2025/09/07 21:45:15 thorpej Exp $        */

/*-
 * Copyright (c) 2023 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Nick Hudson and by Jason R. Thorpe.
 *
 * 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 NETBSD FOUNDATION, INC. 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 FOUNDATION 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/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: gfrtc.c,v 1.7 2025/09/07 21:45:15 thorpej Exp $");

#include <sys/param.h>

#include <sys/bus.h>
#include <sys/device.h>

#include <dev/goldfish/gfrtcvar.h>

#define GOLDFISH_RTC_TIME_LOW           0x00
#define GOLDFISH_RTC_TIME_HIGH          0x04
#define GOLDFISH_RTC_ALARM_LOW          0x08
#define GOLDFISH_RTC_ALARM_HIGH         0x0c
#define GOLDFISH_RTC_IRQ_ENABLED        0x10
#define GOLDFISH_RTC_CLEAR_ALARM        0x14
#define GOLDFISH_RTC_ALARM_STATUS       0x18
#define GOLDFISH_RTC_CLEAR_INTERRUPT    0x1c

/*
 * https://android.googlesource.com/platform/external/qemu/+/master/docs/GOLDFISH-VIRTUAL-HARDWARE.TXT
 *
 * (Despite what the Google docs say, the Qemu goldfish-rtc implements
 * the timer functionality.)
 */

#define GOLDFISH_RTC_READ(sc, reg) \
        bus_space_read_4((sc)->sc_bst, (sc)->sc_bsh, (reg))
#define GOLDFISH_RTC_WRITE(sc, reg, val) \
        bus_space_write_4((sc)->sc_bst, (sc)->sc_bsh, (reg), (val))

static int
gfrtc_gettime(struct todr_chip_handle *ch, struct timeval *tv)
{
        struct gfrtc_softc *sc = device_private(ch->todr_dev);
        const uint64_t nsec = gfrtc_get_time(sc);

        tv->tv_sec = nsec / 1000000000;
        tv->tv_usec = (nsec - tv->tv_sec * 1000000000) / 1000;

        return 0;
}

static int
gfrtc_settime(struct todr_chip_handle *ch, struct timeval *tv)
{
        struct gfrtc_softc *sc = device_private(ch->todr_dev);

        const uint64_t nsec = (tv->tv_sec * 1000000 + tv->tv_usec) * 1000;
        const uint32_t hi = (uint32_t)(nsec >> 32);
        const uint32_t lo = (uint32_t)nsec;

        GOLDFISH_RTC_WRITE(sc, GOLDFISH_RTC_TIME_HIGH, hi);
        GOLDFISH_RTC_WRITE(sc, GOLDFISH_RTC_TIME_LOW, lo);

        return 0;
}


void
gfrtc_attach(struct gfrtc_softc * const sc, bool todr)
{

        aprint_naive("\n");
        aprint_normal(": Google Goldfish RTC + timer\n");

        /* Cancel any alarms, make sure interrupt is disabled. */
        GOLDFISH_RTC_WRITE(sc, GOLDFISH_RTC_IRQ_ENABLED, 0);
        GOLDFISH_RTC_WRITE(sc, GOLDFISH_RTC_CLEAR_ALARM, 0);
        GOLDFISH_RTC_WRITE(sc, GOLDFISH_RTC_CLEAR_INTERRUPT, 0);

        if (todr) {
                aprint_normal_dev(sc->sc_dev,
                    "using as Time of Day Register.\n");
                sc->sc_todr.todr_dev = sc->sc_dev;
                sc->sc_todr.todr_gettime = gfrtc_gettime;
                sc->sc_todr.todr_settime = gfrtc_settime;
                todr_attach(&sc->sc_todr);
        }
}


void
gfrtc_delay(device_t dev, unsigned int usec)
{
        struct gfrtc_softc *sc = device_private(dev);
        uint64_t start_ns, end_ns, min_ns;

        /* Get the start time now while we do the setup work. */
        start_ns = gfrtc_get_time(sc);

        /* Delay for this many nsec. */
        min_ns = (uint64_t)usec * 1000;

        do {
                end_ns = gfrtc_get_time(sc);
        } while ((end_ns - start_ns) < min_ns);
}


uint64_t
gfrtc_get_time(struct gfrtc_softc * const sc)
{
        const uint64_t lo = GOLDFISH_RTC_READ(sc, GOLDFISH_RTC_TIME_LOW);
        const uint64_t hi = GOLDFISH_RTC_READ(sc, GOLDFISH_RTC_TIME_HIGH);

        return (hi << 32) | lo;
}


void
gfrtc_set_alarm(struct gfrtc_softc * const sc, const uint64_t next)
{
        GOLDFISH_RTC_WRITE(sc, GOLDFISH_RTC_ALARM_HIGH, (uint32_t)(next >> 32));
        GOLDFISH_RTC_WRITE(sc, GOLDFISH_RTC_ALARM_LOW, (uint32_t)next);
}


void
gfrtc_clear_alarm(struct gfrtc_softc * const sc)
{
        GOLDFISH_RTC_WRITE(sc, GOLDFISH_RTC_CLEAR_ALARM, 0);
}


void
gfrtc_enable_interrupt(struct gfrtc_softc * const sc)
{
        GOLDFISH_RTC_WRITE(sc, GOLDFISH_RTC_IRQ_ENABLED, 1);
}


void
gfrtc_disable_interrupt(struct gfrtc_softc * const sc)
{
        GOLDFISH_RTC_WRITE(sc, GOLDFISH_RTC_IRQ_ENABLED, 0);
}


void
gfrtc_clear_interrupt(struct gfrtc_softc * const sc)
{
        GOLDFISH_RTC_WRITE(sc, GOLDFISH_RTC_CLEAR_INTERRUPT, 0);
}