/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2017 Hiroki Mori.  All rights reserved.
 * Copyright (c) 2017 Ian Lepore.
 *
 * 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.
 *
 * This code base on isl12xx.c
 */

#include <sys/cdefs.h>
/*
 * Driver for realtime clock EPSON RTC-8583
 */

#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>

#ifdef FDT
#include <dev/ofw/ofw_bus.h>
#include <dev/ofw/ofw_bus_subr.h>
#endif

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

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

#define RTC8583_SC_REG          0x01            /* RTC Seconds */
#define RTC8583_USERSRAM_REG    0x10            /* User SRAM register (first) */
#define MAX_TRANSFER            16

/*
 * A struct laid out in the same order as the time registers in the chip.
 */
struct time_regs {
        uint8_t msec, sec, min, hour, day, month;
};

struct rtc8583_softc {
        device_t        dev;
        device_t        busdev;
        struct intr_config_hook 
                        init_hook;
};

#ifdef FDT
static struct ofw_compat_data compat_data[] = {
        {"epson,rtc8583", 1},
        {NULL,           0},
};
#endif

static void     rtc8583_init(void *arg);
static int      rtc8583_probe(device_t dev);
static int      rtc8583_attach(device_t dev);
static int      rtc8583_detach(device_t dev);

static int      rtc8583_gettime(device_t dev, struct timespec *ts);
static int      rtc8583_settime(device_t dev, struct timespec *ts);

static int      rtc8583_writeto(device_t slavedev, uint8_t regaddr, 
                    void *buffer, uint16_t buflen, int waithow);

/* Implementation */

static int 
rtc8583_writeto(device_t slavedev, uint8_t regaddr, void *buffer,
    uint16_t buflen, int waithow)
{
        struct iic_msg  msgs;
        uint8_t         slaveaddr;
        uint8_t         newbuf[MAX_TRANSFER];

        slaveaddr = iicbus_get_addr(slavedev);

        newbuf[0] = regaddr;
        memcpy(newbuf + 1, buffer, buflen);
        msgs.slave = slaveaddr;
        msgs.flags = IIC_M_WR;
        msgs.len   = 1 + buflen;
        msgs.buf   = newbuf;

        return (iicbus_transfer_excl(slavedev, &msgs, 1, waithow));
}

static inline int
rtc8583_read1(struct rtc8583_softc *sc, uint8_t reg, uint8_t *data) 
{

        return (iicdev_readfrom(sc->dev, reg, data, 1, IIC_WAIT));
}

static inline int
rtc8583_write1(struct rtc8583_softc *sc, uint8_t reg, uint8_t val) 
{

        return (rtc8583_writeto(sc->dev, reg, &val, 1, IIC_WAIT));
}

static void
rtc8583_init(void *arg)
{
        struct rtc8583_softc    *sc;
        
        sc = (struct rtc8583_softc*)arg;
        config_intrhook_disestablish(&sc->init_hook);

        /*
         * Register as a system realtime clock.
         */
        clock_register_flags(sc->dev, 1000000, CLOCKF_SETTIME_NO_ADJ);
        clock_schedule(sc->dev, 1);
        return;
}

static int
rtc8583_probe(device_t dev)
{

#ifdef FDT
        if (!ofw_bus_status_okay(dev))
                return (ENXIO);

        if (ofw_bus_search_compatible(dev, compat_data)->ocd_data != 0) {
                device_set_desc(dev, "EPSON RTC-8583");
                return (BUS_PROBE_DEFAULT);
        }
#endif
        return (ENXIO);
}

static int
rtc8583_attach(device_t dev)
{
        struct rtc8583_softc    *sc;
        
        sc = device_get_softc(dev);
        sc->dev = dev;
        sc->busdev = device_get_parent(sc->dev);

        /*
         * Chip init must wait until interrupts are enabled.  Often i2c access
         * works only when the interrupts are available.
         */
        sc->init_hook.ich_func = rtc8583_init;
        sc->init_hook.ich_arg = sc;
        if (config_intrhook_establish(&sc->init_hook) != 0)
                return (ENOMEM);

        return (0);
}

static int
rtc8583_detach(device_t dev)
{

        clock_unregister(dev);
        return (0);
}

static int
rtc8583_gettime(device_t dev, struct timespec *ts)
{
        struct rtc8583_softc    *sc;
        struct bcd_clocktime     bct;
        struct time_regs         tregs;
        uint8_t                  y, ytmp, sreg;
        int                      err;

        sc = device_get_softc(dev);

        /* Read the bcd time registers. */
        if ((err = iicdev_readfrom(sc->dev, RTC8583_SC_REG, &tregs, sizeof(tregs),
            IIC_WAIT)) != 0)
                return (err);

        y = tregs.day >> 6;
        /* Get year from user SRAM */
        rtc8583_read1(sc, RTC8583_USERSRAM_REG,  &sreg);
        
        /* 
         * Check if year adjustment is required.
         * RTC has only 2 bits for year value (i.e. maximum is 4 years), so
         * full year value is stored in user SRAM and updated manually or 
         * by this code.
         */
        ytmp = sreg & 0x03;
        if (ytmp != y) {
                /* shift according to difference */
                sreg += y - ytmp;
                
                /* check if overflow happened */
                if (ytmp > y)
                        sreg += 4;
                
                if ((err = iicbus_request_bus(sc->busdev, sc->dev, IIC_WAIT)) != 0)
                        return (err);
                rtc8583_write1(sc, RTC8583_USERSRAM_REG, sreg);
                iicbus_release_bus(sc->busdev, sc->dev);
        }

        if (!validbcd(tregs.msec))
                return (EINVAL);

        /* The 'msec' reg is actually 1/100ths, in bcd.  */
        bct.nsec = bcd2bin(tregs.msec) * 10 * 1000 * 1000;
        bct.sec  = tregs.sec;
        bct.min  = tregs.min;
        bct.hour = tregs.hour & 0x3f;
        bct.day  = tregs.day & 0x3f;
        bct.mon  = tregs.month & 0x1f;
        bct.year = bin2bcd(sreg % 100);

        clock_dbgprint_bcd(sc->dev, CLOCK_DBG_READ, &bct); 
        return (clock_bcd_to_ts(&bct, ts, false));
}

static int
rtc8583_settime(device_t dev, struct timespec *ts)
{
        struct rtc8583_softc    *sc;
        struct bcd_clocktime     bct;
        struct time_regs         tregs;
        uint8_t                  sreg;
        int                      err;

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

        /* The 'msec' reg is actually 1/100ths, in bcd.  */
        tregs.msec  = bin2bcd(ts->tv_nsec / (10 * 1000 * 1000));
        tregs.sec   = bct.sec;
        tregs.min   = bct.min;
        tregs.hour  = bct.hour;
        tregs.day   = bct.day | (bct.year & 0x03 << 6);
        tregs.month = bct.mon;

        if ((err = iicbus_request_bus(sc->busdev, sc->dev, IIC_WAIT)) != 0)
                return (err);
        err = rtc8583_writeto(sc->dev, RTC8583_SC_REG, &tregs,
            sizeof(tregs), IIC_WAIT);
        sreg = bcd2bin(bct.year & 0xff);
        /* save to year to sram */
        rtc8583_write1(sc, RTC8583_USERSRAM_REG, sreg);
        iicbus_release_bus(sc->busdev, sc->dev);

        return (err);
}

static device_method_t rtc8583_methods[] = {
        /* device_if methods */
        DEVMETHOD(device_probe,         rtc8583_probe),
        DEVMETHOD(device_attach,        rtc8583_attach),
        DEVMETHOD(device_detach,        rtc8583_detach),

        /* clock_if methods */
        DEVMETHOD(clock_gettime,        rtc8583_gettime),
        DEVMETHOD(clock_settime,        rtc8583_settime),

        DEVMETHOD_END,
};

static driver_t rtc8583_driver = {
        "rtc8583",
        rtc8583_methods,
        sizeof(struct rtc8583_softc),
};

DRIVER_MODULE(rtc8583, iicbus, rtc8583_driver, NULL, NULL);
MODULE_VERSION(rtc8583, 1);
MODULE_DEPEND(rtc8583, iicbus, IICBUS_MINVER, IICBUS_PREFVER, IICBUS_MAXVER);
IICBUS_FDT_PNP_INFO(compat_data);