/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2020 Alstom Group.
 * Copyright (c) 2020 Semihalf.
 *
 * 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>
#include "opt_platform.h"

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/bus.h>
#include <sys/clock.h>
#include <sys/kernel.h>
#include <sys/lock.h>
#include <sys/module.h>

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

#include <dev/iicbus/iiconf.h>
#include <dev/iicbus/iicbus.h>

#include "clock_if.h"
#include "iicbus_if.h"

#define BIT(x)                  (1 << (x))

#define RX8803_TIME             0x0
#define RX8803_FLAGS            0xE
#define RX8803_CTRL             0xF

#define RX8803_FLAGS_V1F        BIT(0)
#define RX8803_FLAGS_V2F        BIT(1)

#define RX8803_CTRL_DISABLE     BIT(0)

#define HALF_OF_SEC_NS          500000000
#define MAX_WRITE_LEN           16

struct rx8803_time {
        uint8_t sec;
        uint8_t min;
        uint8_t hour;
        uint8_t dow;
        uint8_t day;
        uint8_t mon;
        uint8_t year;
};

static struct ofw_compat_data compat_data[] = {
        {"epson,rx8803", 1},
        {NULL,           0},
};

static int rx8803_probe(device_t dev);
static int rx8803_attach(device_t dev);
static int rx8803_detach(device_t dev);

static int rx8803_gettime(device_t dev, struct timespec *ts);
static int rx8803_settime(device_t dev, struct timespec *ts);

static int rx8803_check_status(device_t dev);

static int
rx8803_check_status(device_t dev)
{
        uint8_t flags;
        int rc;

        rc = iicdev_readfrom(dev, RX8803_FLAGS, &flags, 1, IIC_WAIT);
        if (rc != 0)
                return (rc);

        if (flags & RX8803_FLAGS_V2F) {
                device_printf(dev, "Low voltage flag set, date is incorrect\n");
                return (ENXIO);
        }

        return (0);
}

static int
rx8803_gettime(device_t dev, struct timespec *ts)
{
        struct rx8803_time data;
        struct bcd_clocktime bcd;
        int rc;

        rc = rx8803_check_status(dev);
        if (rc != 0)
                return (rc);

        rc = iicdev_readfrom(dev,
            RX8803_TIME,
            &data, sizeof(struct rx8803_time),
            IIC_WAIT);
        if (rc != 0)
                return (rc);

        bcd.nsec = 0;
        bcd.sec = data.sec & 0x7F;
        bcd.min = data.min & 0x7F;
        bcd.hour = data.hour & 0x3F;
        bcd.dow = flsl(data.dow & 0x7F) - 1;
        bcd.day = data.day & 0x3F;
        bcd.mon = (data.mon & 0x1F);
        bcd.year = data.year;

        clock_dbgprint_bcd(dev, CLOCK_DBG_READ, &bcd);

        rc = clock_bcd_to_ts(&bcd, ts, false);
        return (rc);
}

static int
rx8803_settime(device_t dev, struct timespec *ts)
{
        struct rx8803_time data;
        struct bcd_clocktime bcd;
        uint8_t reg;
        int rc;

        ts->tv_sec -= utc_offset();
        clock_ts_to_bcd(ts, &bcd, false);
        clock_dbgprint_bcd(dev, CLOCK_DBG_WRITE, &bcd);

        data.sec = bcd.sec;
        data.min = bcd.min;
        data.hour = bcd.hour;
        data.dow = 1 << bcd.dow;
        data.day = bcd.day;
        data.mon = bcd.mon;
        data.year = bcd.year;

        if (ts->tv_nsec > HALF_OF_SEC_NS)
                data.sec++;

        /* First disable clock. */
        rc = iicdev_readfrom(dev, RX8803_CTRL, &reg, sizeof(uint8_t), IIC_WAIT);
        if (rc != 0)
                return (rc);

        reg |= RX8803_CTRL_DISABLE;

        rc = iicdev_writeto(dev, RX8803_CTRL, &reg, sizeof(uint8_t), IIC_WAIT);
        if (rc != 0)
                return (rc);

        /* Update the date. */
        rc = iicdev_writeto(dev,
            RX8803_TIME,
            &data, sizeof(struct rx8803_time),
            IIC_WAIT);
        if (rc != 0)
                return (rc);

        /* Now restart it. */
        reg &= ~RX8803_CTRL_DISABLE;
        rc = iicdev_writeto(dev, RX8803_CTRL, &reg, sizeof(uint8_t), IIC_WAIT);
        if (rc != 0)
                return (rc);

        /* Clear low voltage flags, as we have just updated the clock. */
        rc = iicdev_readfrom(dev, RX8803_FLAGS, &reg, sizeof(uint8_t), IIC_WAIT);
        if (rc != 0)
                return (rc);

        reg &= ~(RX8803_FLAGS_V1F | RX8803_FLAGS_V2F);
        rc = iicdev_writeto(dev, RX8803_FLAGS, &reg, sizeof(uint8_t), IIC_WAIT);
        return (rc);
}

static int
rx8803_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, "Epson RX8803 Real Time Clock");

        return (BUS_PROBE_GENERIC);
}

static int
rx8803_attach(device_t dev)
{

        /* Set 1 sec resolution. */
        clock_register_flags(dev, 1000000, 0);
        clock_schedule(dev, 1);

        return (0);

}

static int
rx8803_detach(device_t dev)
{

        clock_unregister(dev);

        return (0);
}

static device_method_t rx8803_methods[] = {
        DEVMETHOD(device_probe, rx8803_probe),
        DEVMETHOD(device_attach, rx8803_attach),
        DEVMETHOD(device_detach, rx8803_detach),

        DEVMETHOD(clock_gettime, rx8803_gettime),
        DEVMETHOD(clock_settime, rx8803_settime),

        DEVMETHOD_END,
};

static driver_t rx8803_driver = {
        "rx8803",
        rx8803_methods,
        0,                      /* We don't need softc for this one. */
};

DRIVER_MODULE(rx8803, iicbus, rx8803_driver, NULL, NULL);
MODULE_VERSION(rx8803, 1);
MODULE_DEPEND(rx8803, iicbus, IICBUS_MINVER, IICBUS_PREFVER, IICBUS_MAXVER);
IICBUS_FDT_PNP_INFO(compat_data);