/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2000 Sascha Schumann. All rights reserved.
 *
 * 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 SASCHA SCHUMANN ``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 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>
#include "opt_pcfclock.h"

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/bus.h>
#include <sys/sockio.h>
#include <sys/mbuf.h>
#include <sys/kernel.h>
#include <sys/module.h>
#include <sys/conf.h>
#include <sys/fcntl.h>
#include <sys/uio.h>

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

#include <dev/ppbus/ppbconf.h>
#include <dev/ppbus/ppb_msq.h>
#include <dev/ppbus/ppbio.h>

#include "ppbus_if.h"

#define PCFCLOCK_NAME "pcfclock"

struct pcfclock_data {
        device_t dev;
        struct cdev *cdev;
};

static  d_open_t                pcfclock_open;
static  d_close_t               pcfclock_close;
static  d_read_t                pcfclock_read;

static struct cdevsw pcfclock_cdevsw = {
        .d_version =    D_VERSION,
        .d_open =       pcfclock_open,
        .d_close =      pcfclock_close,
        .d_read =       pcfclock_read,
        .d_name =       PCFCLOCK_NAME,
};

#ifndef PCFCLOCK_MAX_RETRIES
#define PCFCLOCK_MAX_RETRIES 10
#endif

#define AFC_HI 0
#define AFC_LO AUTOFEED

/* AUTO FEED is used as clock */
#define AUTOFEED_CLOCK(val) \
        ctr = (ctr & ~(AUTOFEED)) ^ (val); ppb_wctr(ppbus, ctr)

/* SLCT is used as clock */
#define CLOCK_OK \
        ((ppb_rstr(ppbus) & SELECT) == (i & 1 ? SELECT : 0))

/* PE is used as data */
#define BIT_SET (ppb_rstr(ppbus)&PERROR)

/* the first byte sent as reply must be 00001001b */
#define PCFCLOCK_CORRECT_SYNC(buf) (buf[0] == 9)

#define NR(buf, off) (buf[off+1]*10+buf[off])

/* check for correct input values */
#define PCFCLOCK_CORRECT_FORMAT(buf) (\
        NR(buf, 14) <= 99 && \
        NR(buf, 12) <= 12 && \
        NR(buf, 10) <= 31 && \
        NR(buf,  6) <= 23 && \
        NR(buf,  4) <= 59 && \
        NR(buf,  2) <= 59)

#define PCFCLOCK_BATTERY_STATUS_LOW(buf) (buf[8] & 4)

#define PCFCLOCK_CMD_TIME 0             /* send current time */
#define PCFCLOCK_CMD_COPY 7     /* copy received signal to PC */

static void
pcfclock_identify(driver_t *driver, device_t parent)
{

        device_t dev;

        dev = device_find_child(parent, PCFCLOCK_NAME, DEVICE_UNIT_ANY);
        if (!dev)
                BUS_ADD_CHILD(parent, 0, PCFCLOCK_NAME, DEVICE_UNIT_ANY);
}

static int
pcfclock_probe(device_t dev)
{

        device_set_desc(dev, "PCF-1.0");
        return (0);
}

static int
pcfclock_attach(device_t dev)
{
        struct pcfclock_data *sc = device_get_softc(dev);
        int unit;

        unit = device_get_unit(dev);

        sc->dev = dev;
        sc->cdev = make_dev(&pcfclock_cdevsw, unit,
                        UID_ROOT, GID_WHEEL, 0400, PCFCLOCK_NAME "%d", unit);
        if (sc->cdev == NULL) {
                device_printf(dev, "Failed to create character device\n");
                return (ENXIO);
        }
        sc->cdev->si_drv1 = sc;

        return (0);
}

static int
pcfclock_open(struct cdev *dev, int flag, int fms, struct thread *td)
{
        struct pcfclock_data *sc = dev->si_drv1;
        device_t pcfclockdev;
        device_t ppbus;
        int res;

        if (!sc)
                return (ENXIO);
        pcfclockdev = sc->dev;
        ppbus = device_get_parent(pcfclockdev);

        ppb_lock(ppbus);
        res = ppb_request_bus(ppbus, pcfclockdev,
            (flag & O_NONBLOCK) ? PPB_DONTWAIT : PPB_WAIT);
        ppb_unlock(ppbus);
        return (res);
}

static int
pcfclock_close(struct cdev *dev, int flags, int fmt, struct thread *td)
{
        struct pcfclock_data *sc = dev->si_drv1;
        device_t pcfclockdev = sc->dev;
        device_t ppbus = device_get_parent(pcfclockdev);

        ppb_lock(ppbus);
        ppb_release_bus(ppbus, pcfclockdev);
        ppb_unlock(ppbus);

        return (0);
}

static void
pcfclock_write_cmd(struct cdev *dev, unsigned char command)
{
        struct pcfclock_data *sc = dev->si_drv1;
        device_t pcfclockdev = sc->dev;
        device_t ppbus = device_get_parent(pcfclockdev);
        unsigned char ctr = 14;
        char i;

        for (i = 0; i <= 7; i++) {
                ppb_wdtr(ppbus, i);
                AUTOFEED_CLOCK(i & 1 ? AFC_HI : AFC_LO);
                DELAY(3000);
        }
        ppb_wdtr(ppbus, command);
        AUTOFEED_CLOCK(AFC_LO);
        DELAY(3000);
        AUTOFEED_CLOCK(AFC_HI);
}

static void
pcfclock_display_data(struct cdev *dev, char buf[18])
{
        struct pcfclock_data *sc = dev->si_drv1;
#ifdef PCFCLOCK_VERBOSE
        int year;

        year = NR(buf, 14);
        if (year < 70)
                year += 100;

        device_printf(sc->dev, "%02d.%02d.%4d %02d:%02d:%02d, "
                        "battery status: %s\n",
                        NR(buf, 10), NR(buf, 12), 1900 + year,
                        NR(buf, 6), NR(buf, 4), NR(buf, 2),
                        PCFCLOCK_BATTERY_STATUS_LOW(buf) ? "LOW" : "ok");
#else
        if (PCFCLOCK_BATTERY_STATUS_LOW(buf))
                device_printf(sc->dev, "BATTERY STATUS LOW ON\n");
#endif
}

static int
pcfclock_read_data(struct cdev *dev, char *buf, ssize_t bits)
{
        struct pcfclock_data *sc = dev->si_drv1;
        device_t pcfclockdev = sc->dev;
        device_t ppbus = device_get_parent(pcfclockdev);
        int i;
        char waitfor;
        int offset;

        /* one byte per four bits */
        bzero(buf, ((bits + 3) >> 2) + 1);

        waitfor = 100;
        for (i = 0; i <= bits; i++) {
                /* wait for clock, maximum (waitfor*100) usec */
                while (!CLOCK_OK && --waitfor > 0)
                        DELAY(100);

                /* timed out? */
                if (!waitfor)
                        return (EIO);

                waitfor = 100; /* reload */

                /* give it some time */
                DELAY(500);

                /* calculate offset into buffer */
                offset = i >> 2;
                buf[offset] <<= 1;

                if (BIT_SET)
                        buf[offset] |= 1;
        }

        return (0);
}

static int
pcfclock_read_dev(struct cdev *dev, char *buf, int maxretries)
{
        struct pcfclock_data *sc = dev->si_drv1;
        device_t pcfclockdev = sc->dev;
        device_t ppbus = device_get_parent(pcfclockdev);
        int error = 0;

        ppb_set_mode(ppbus, PPB_COMPATIBLE);

        while (--maxretries > 0) {
                pcfclock_write_cmd(dev, PCFCLOCK_CMD_TIME);
                if (pcfclock_read_data(dev, buf, 68))
                        continue;

                if (!PCFCLOCK_CORRECT_SYNC(buf))
                        continue;

                if (!PCFCLOCK_CORRECT_FORMAT(buf))
                        continue;

                break;
        }

        if (!maxretries)
                error = EIO;

        return (error);
}

static int
pcfclock_read(struct cdev *dev, struct uio *uio, int ioflag)
{
        struct pcfclock_data *sc = dev->si_drv1;
        device_t ppbus;
        char buf[18];
        int error = 0;

        if (uio->uio_resid < 18)
                return (ERANGE);

        ppbus = device_get_parent(sc->dev);
        ppb_lock(ppbus);
        error = pcfclock_read_dev(dev, buf, PCFCLOCK_MAX_RETRIES);
        ppb_unlock(ppbus);

        if (error) {
                device_printf(sc->dev, "no PCF found\n");
        } else {
                pcfclock_display_data(dev, buf);

                uiomove(buf, 18, uio);
        }

        return (error);
}

static device_method_t pcfclock_methods[] = {
        /* device interface */
        DEVMETHOD(device_identify,      pcfclock_identify),
        DEVMETHOD(device_probe,         pcfclock_probe),
        DEVMETHOD(device_attach,        pcfclock_attach),
        DEVMETHOD_END
};

static driver_t pcfclock_driver = {
        PCFCLOCK_NAME,
        pcfclock_methods,
        sizeof(struct pcfclock_data),
};

DRIVER_MODULE(pcfclock, ppbus, pcfclock_driver, 0, 0);