/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2017 Ian Lepore <ian@freebsd.org>
 *
 * 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 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 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>
/*
 * Driver for Dallas/Maxim DS13xx real-time clock/calendar chips:
 *
 * - DS1307 = Original/basic rtc + 56 bytes ram; 5v only.
 * - DS1308 = Updated 1307, available in 1.8v-5v variations.
 * - DS1337 = Like 1308, integrated xtal, 32khz output on at powerup.
 * - DS1338 = Like 1308, integrated xtal.
 * - DS1339 = Like 1337, integrated xtal, integrated trickle charger.
 * - DS1340 = Like 1338, ST M41T00 compatible.
 * - DS1341 = Like 1338, can slave-sync osc to external clock signal.
 * - DS1342 = Like 1341 but requires different xtal.
 * - DS1371 = 32-bit binary counter, watchdog timer.
 * - DS1372 = 32-bit binary counter, 64-bit unique id in rom.
 * - DS1374 = 32-bit binary counter, watchdog timer, trickle charger.
 * - DS1375 = Like 1308 but only 16 bytes ram.
 * - DS1388 = Rtc, watchdog timer, 512 bytes eeprom (not sram).
 *
 * This driver supports only basic timekeeping functions.  It provides no access
 * to or control over any other functionality provided by the chips.
 */

#include "opt_platform.h"

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

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

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

/*
 * I2C address 1101 000x
 */
#define DS13xx_ADDR             0xd0

/*
 * Registers, bits within them, and masks for the various chip types.
 */

#define DS13xx_R_NONE           0xff    /* Placeholder */

#define DS130x_R_CONTROL        0x07
#define DS133x_R_CONTROL        0x0e
#define DS1340_R_CONTROL        0x07
#define DS1341_R_CONTROL        0x0e
#define DS1371_R_CONTROL        0x07
#define DS1372_R_CONTROL        0x07
#define DS1374_R_CONTROL        0x07
#define DS1375_R_CONTROL        0x0e
#define DS1388_R_CONTROL        0x0c

#define DS13xx_R_SECOND         0x00
#define DS1388_R_SECOND         0x01

#define DS130x_R_STATUS         DS13xx_R_NONE
#define DS133x_R_STATUS         0x0f
#define DS1340_R_STATUS         0x09
#define DS137x_R_STATUS         0x08
#define DS1388_R_STATUS         0x0b

#define DS13xx_B_STATUS_OSF     0x80    /* OSF is 1<<7 in status and sec regs */
#define DS13xx_B_HOUR_AMPM      0x40    /* AMPM mode is bit 1<<6 */
#define DS13xx_B_HOUR_PM        0x20    /* PM hours indicated by 1<<5 */
#define DS13xx_B_MONTH_CENTURY  0x80    /* 21st century indicated by 1<<7 */

#define DS13xx_M_SECOND         0x7f    /* Masks for all BCD time regs... */
#define DS13xx_M_MINUTE         0x7f
#define DS13xx_M_12HOUR         0x1f
#define DS13xx_M_24HOUR         0x3f
#define DS13xx_M_DAY            0x3f
#define DS13xx_M_MONTH          0x1f
#define DS13xx_M_YEAR           0xff

/*
 * The chip types we support.
 */
enum {
        TYPE_NONE,
        TYPE_DS1307,
        TYPE_DS1308,
        TYPE_DS1337,
        TYPE_DS1338,
        TYPE_DS1339,
        TYPE_DS1340,
        TYPE_DS1341,
        TYPE_DS1342,
        TYPE_DS1371,
        TYPE_DS1372,
        TYPE_DS1374,
        TYPE_DS1375,
        TYPE_DS1388,

        TYPE_COUNT
};
static const char *desc_strings[] = {
        "",
        "Dallas/Maxim DS1307 RTC",
        "Dallas/Maxim DS1308 RTC",
        "Dallas/Maxim DS1337 RTC",
        "Dallas/Maxim DS1338 RTC",
        "Dallas/Maxim DS1339 RTC",
        "Dallas/Maxim DS1340 RTC",
        "Dallas/Maxim DS1341 RTC",
        "Dallas/Maxim DS1342 RTC",
        "Dallas/Maxim DS1371 RTC",
        "Dallas/Maxim DS1372 RTC",
        "Dallas/Maxim DS1374 RTC",
        "Dallas/Maxim DS1375 RTC",
        "Dallas/Maxim DS1388 RTC",
};
CTASSERT(nitems(desc_strings) == TYPE_COUNT);

/*
 * The time registers in the order they are laid out in hardware.
 */
struct time_regs {
        uint8_t sec, min, hour, wday, day, month, year;
};

struct ds13rtc_softc {
        device_t        dev;
        device_t        busdev;
        u_int           chiptype;       /* Type of DS13xx chip */
        uint8_t         secaddr;        /* Address of seconds register */
        uint8_t         osfaddr;        /* Address of register with OSF */
        bool            use_ampm;       /* Use AM/PM mode. */
        bool            use_century;    /* Use the Century bit. */
        bool            is_binary_counter; /* Chip has 32-bit binary counter. */
};

/*
 * We use the compat_data table to look up hint strings in the non-FDT case, so
 * define the struct locally when we don't get it from ofw_bus_subr.h.
 */
#ifdef FDT
typedef struct ofw_compat_data ds13_compat_data;
#else
typedef struct {
        const char *ocd_str;
        uintptr_t  ocd_data;
} ds13_compat_data;
#endif

static ds13_compat_data compat_data[] = {
        {"dallas,ds1307",   TYPE_DS1307},
        {"dallas,ds1308",   TYPE_DS1308},
        {"dallas,ds1337",   TYPE_DS1337},
        {"dallas,ds1338",   TYPE_DS1338},
        {"dallas,ds1339",   TYPE_DS1339},
        {"dallas,ds1340",   TYPE_DS1340},
        {"dallas,ds1341",   TYPE_DS1341},
        {"dallas,ds1342",   TYPE_DS1342},
        {"dallas,ds1371",   TYPE_DS1371},
        {"dallas,ds1372",   TYPE_DS1372},
        {"dallas,ds1374",   TYPE_DS1374},
        {"dallas,ds1375",   TYPE_DS1375},
        {"dallas,ds1388",   TYPE_DS1388},

        {NULL,              TYPE_NONE},
};

static int
read_reg(struct ds13rtc_softc *sc, uint8_t reg, uint8_t *val)
{

        return (iicdev_readfrom(sc->dev, reg, val, sizeof(*val), IIC_WAIT));
}

static int
write_reg(struct ds13rtc_softc *sc, uint8_t reg, uint8_t val)
{

        return (iicdev_writeto(sc->dev, reg, &val, sizeof(val), IIC_WAIT));
}

static int
read_timeregs(struct ds13rtc_softc *sc, struct time_regs *tregs)
{
        int err;

        if ((err = iicdev_readfrom(sc->dev, sc->secaddr, tregs,
            sizeof(*tregs), IIC_WAIT)) != 0)
                return (err);

        return (err);
}

static int
write_timeregs(struct ds13rtc_softc *sc, struct time_regs *tregs)
{

        return (iicdev_writeto(sc->dev, sc->secaddr, tregs,
            sizeof(*tregs), IIC_WAIT));
}

static int
read_timeword(struct ds13rtc_softc *sc, time_t *secs)
{
        int err;
        uint8_t buf[4];

        if ((err = iicdev_readfrom(sc->dev, sc->secaddr, buf, sizeof(buf),
            IIC_WAIT)) == 0)
                *secs = le32dec(buf);

        return (err);
}

static int
write_timeword(struct ds13rtc_softc *sc, time_t secs)
{
        uint8_t buf[4];

        le32enc(buf, (uint32_t)secs);
        return (iicdev_writeto(sc->dev, sc->secaddr, buf, sizeof(buf),
            IIC_WAIT));
}

static void
ds13rtc_start(void *arg)
{
        struct ds13rtc_softc *sc;
        uint8_t ctlreg, statreg;

        sc = arg;

        /*
         * Every chip in this family can be usefully initialized by writing 0 to
         * the control register, except DS1375 which has an external oscillator
         * controlled by values in the ctlreg that we know nothing about, so
         * we'd best leave them alone.  For all other chips, writing 0 enables
         * the oscillator, disables signals/outputs in battery-backed mode
         * (saves power) and disables features like watchdog timers and alarms.
         */
        switch (sc->chiptype) {
        case TYPE_DS1307:
        case TYPE_DS1308:
        case TYPE_DS1338:
        case TYPE_DS1340:
        case TYPE_DS1371:
        case TYPE_DS1372:
        case TYPE_DS1374:
                ctlreg = DS130x_R_CONTROL;
                break;
        case TYPE_DS1337:
        case TYPE_DS1339:
                ctlreg = DS133x_R_CONTROL;
                break;
        case TYPE_DS1341:
        case TYPE_DS1342:
                ctlreg = DS1341_R_CONTROL;
                break;
        case TYPE_DS1375:
                ctlreg = DS13xx_R_NONE;
                break;
        case TYPE_DS1388:
                ctlreg = DS1388_R_CONTROL;
                break;
        default:
                device_printf(sc->dev, "missing init code for this chiptype\n");
                return;
        }
        if (ctlreg != DS13xx_R_NONE)
                write_reg(sc, ctlreg, 0);

        /*
         * Common init.  Read the OSF/CH status bit and report stopped clocks to
         * the user.  The status bit will be cleared the first time we write
         * valid time to the chip (and must not be cleared before that).
         */
        if (read_reg(sc, sc->osfaddr, &statreg) != 0) {
                device_printf(sc->dev, "cannot read RTC clock status bit\n");
                return;
        }
        if (statreg & DS13xx_B_STATUS_OSF) {
                device_printf(sc->dev, 
                    "WARNING: RTC battery failed; time is invalid\n");
        }

        /*
         * Figure out whether the chip is configured for AM/PM mode.  On all
         * chips that do AM/PM mode, the flag bit is in the hours register,
         * which is secaddr+2.
         */
        if ((sc->chiptype != TYPE_DS1340) && !sc->is_binary_counter) {
                if (read_reg(sc, sc->secaddr + 2, &statreg) != 0) {
                        device_printf(sc->dev,
                            "cannot read RTC clock AM/PM bit\n");
                        return;
                }
                if (statreg & DS13xx_B_HOUR_AMPM)
                        sc->use_ampm = true;
        }

        /*
         * Everything looks good if we make it to here; register as an RTC.
         * Schedule RTC updates to happen just after top-of-second.
         */
        clock_register_flags(sc->dev, 1000000, CLOCKF_SETTIME_NO_ADJ);
        clock_schedule(sc->dev, 1);
}

static int
ds13rtc_gettime(device_t dev, struct timespec *ts)
{
        struct bcd_clocktime bct;
        struct time_regs tregs;
        struct ds13rtc_softc *sc;
        int err;
        uint8_t statreg, hourmask;

        sc = device_get_softc(dev);

        /* Read the OSF/CH bit; if the clock stopped we can't provide time. */
        if ((err = read_reg(sc, sc->osfaddr, &statreg)) != 0) {
                return (err);
        }
        if (statreg & DS13xx_B_STATUS_OSF)
                return (EINVAL); /* hardware is good, time is not. */

        /* If the chip counts time in binary, we just read and return it. */
        if (sc->is_binary_counter) {
                ts->tv_nsec = 0;
                return (read_timeword(sc, &ts->tv_sec));
        }

        /*
         * Chip counts in BCD, read and decode it...
         */
        if ((err = read_timeregs(sc, &tregs)) != 0) {
                device_printf(dev, "cannot read RTC time\n");
                return (err);
        }

        if (sc->use_ampm)
                hourmask = DS13xx_M_12HOUR;
        else
                hourmask = DS13xx_M_24HOUR;

        bct.nsec = 0;
        bct.ispm = tregs.hour  & DS13xx_B_HOUR_PM;
        bct.sec  = tregs.sec   & DS13xx_M_SECOND;
        bct.min  = tregs.min   & DS13xx_M_MINUTE;
        bct.hour = tregs.hour  & hourmask;
        bct.day  = tregs.day   & DS13xx_M_DAY;
        bct.mon  = tregs.month & DS13xx_M_MONTH;
        bct.year = tregs.year  & DS13xx_M_YEAR;

        /*
         * If this chip has a century bit, honor it.  Otherwise let
         * clock_ct_to_ts() infer the century from the 2-digit year.
         */
        if (sc->use_century)
                bct.year += (tregs.month & DS13xx_B_MONTH_CENTURY) ? 0x100 : 0;

        clock_dbgprint_bcd(sc->dev, CLOCK_DBG_READ, &bct); 
        err = clock_bcd_to_ts(&bct, ts, sc->use_ampm);

        return (err);
}

static int
ds13rtc_settime(device_t dev, struct timespec *ts)
{
        struct bcd_clocktime bct;
        struct time_regs tregs;
        struct ds13rtc_softc *sc;
        int err;
        uint8_t cflag, statreg, pmflags;

        sc = device_get_softc(dev);

        /*
         * We request a timespec with no resolution-adjustment.  That also
         * disables utc adjustment, so apply that ourselves.
         */
        ts->tv_sec -= utc_offset();

        /* If the chip counts time in binary, store tv_sec and we're done. */
        if (sc->is_binary_counter)
                return (write_timeword(sc, ts->tv_sec));

        clock_ts_to_bcd(ts, &bct, sc->use_ampm);
        clock_dbgprint_bcd(sc->dev, CLOCK_DBG_WRITE, &bct); 

        /* If the chip is in AMPM mode deal with the PM flag. */
        pmflags = 0;
        if (sc->use_ampm) {
                pmflags = DS13xx_B_HOUR_AMPM;
                if (bct.ispm)
                        pmflags |= DS13xx_B_HOUR_PM;
        }

        /* If the chip has a century bit, set it as needed. */
        cflag = 0;
        if (sc->use_century) {
                if (bct.year >= 2000)
                        cflag |= DS13xx_B_MONTH_CENTURY;
        }

        tregs.sec   = bct.sec;
        tregs.min   = bct.min;
        tregs.hour  = bct.hour | pmflags;
        tregs.day   = bct.day;
        tregs.month = bct.mon | cflag;
        tregs.year  = bct.year & 0xff;
        tregs.wday  = bct.dow;

        /*
         * Set the time.  Reset the OSF bit if it is on and it is not part of
         * the time registers (in which case writing time resets it).
         */
        if ((err = write_timeregs(sc, &tregs)) != 0)
                goto errout;
        if (sc->osfaddr != sc->secaddr) {
                if ((err = read_reg(sc, sc->osfaddr, &statreg)) != 0)
                        goto errout;
                if (statreg & DS13xx_B_STATUS_OSF) {
                        statreg &= ~DS13xx_B_STATUS_OSF;
                        err = write_reg(sc, sc->osfaddr, statreg);
                }
        }

errout:

        if (err != 0)
                device_printf(dev, "cannot update RTC time\n");

        return (err);
}

static int
ds13rtc_get_chiptype(device_t dev)
{
#ifdef FDT

        return (ofw_bus_search_compatible(dev, compat_data)->ocd_data);
#else
        ds13_compat_data *cdata;
        const char *htype; 

        /*
         * We can only attach if provided a chiptype hint string.
         */
        if (resource_string_value(device_get_name(dev), 
            device_get_unit(dev), "compatible", &htype) != 0)
                return (TYPE_NONE);

        /*
         * Loop through the ofw compat data comparing the hinted chip type to
         * the compat strings.
         */
        for (cdata = compat_data; cdata->ocd_str != NULL; ++cdata) {
                if (strcmp(htype, cdata->ocd_str) == 0)
                        break;
        }
        return (cdata->ocd_data);
#endif
}

static int
ds13rtc_probe(device_t dev)
{
        int chiptype, goodrv;

#ifdef FDT
        if (!ofw_bus_status_okay(dev))
                return (ENXIO);
        goodrv = BUS_PROBE_GENERIC;
#else
        goodrv = BUS_PROBE_NOWILDCARD;
#endif

        chiptype = ds13rtc_get_chiptype(dev);
        if (chiptype == TYPE_NONE)
                return (ENXIO);

        device_set_desc(dev, desc_strings[chiptype]);
        return (goodrv);
}

static int
ds13rtc_attach(device_t dev)
{
        struct ds13rtc_softc *sc;

        sc = device_get_softc(dev);
        sc->dev = dev;
        sc->busdev = device_get_parent(dev);

        /*
         * We need to know what kind of chip we're driving.
         */
        if ((sc->chiptype = ds13rtc_get_chiptype(dev)) == TYPE_NONE) {
                device_printf(dev, "impossible: cannot determine chip type\n");
                return (ENXIO);
        }

        /* The seconds register is in the same place on all except DS1388. */
        if (sc->chiptype == TYPE_DS1388) 
                sc->secaddr = DS1388_R_SECOND;
        else
                sc->secaddr = DS13xx_R_SECOND;

        /*
         * The OSF/CH (osc failed/clock-halted) bit appears in different
         * registers for different chip types.  The DS1375 has no OSF indicator
         * because it has no internal oscillator; we just point to an always-
         * zero bit in the status register for that chip.
         */
        switch (sc->chiptype) {
        case TYPE_DS1307:
        case TYPE_DS1308:
        case TYPE_DS1338:
                sc->osfaddr = DS13xx_R_SECOND;
                break;
        case TYPE_DS1337:
        case TYPE_DS1339:
        case TYPE_DS1341:
        case TYPE_DS1342:
        case TYPE_DS1375:
                sc->osfaddr = DS133x_R_STATUS;
                sc->use_century = true;
                break;
        case TYPE_DS1340:
                sc->osfaddr = DS1340_R_STATUS;
                break;
        case TYPE_DS1371:
        case TYPE_DS1372:
        case TYPE_DS1374:
                sc->osfaddr = DS137x_R_STATUS;
                sc->is_binary_counter = true;
                break;
        case TYPE_DS1388:
                sc->osfaddr = DS1388_R_STATUS;
                break;
        }

        /*
         * We have to wait until interrupts are enabled.  Sometimes I2C read
         * and write only works when the interrupts are available.
         */
        config_intrhook_oneshot(ds13rtc_start, sc);

        return (0);
}

static int
ds13rtc_detach(device_t dev)
{

        clock_unregister(dev);
        return (0);
}

static device_method_t ds13rtc_methods[] = {
        DEVMETHOD(device_probe,         ds13rtc_probe),
        DEVMETHOD(device_attach,        ds13rtc_attach),
        DEVMETHOD(device_detach,        ds13rtc_detach),

        DEVMETHOD(clock_gettime,        ds13rtc_gettime),
        DEVMETHOD(clock_settime,        ds13rtc_settime),

        DEVMETHOD_END
};

static driver_t ds13rtc_driver = {
        "ds13rtc",
        ds13rtc_methods,
        sizeof(struct ds13rtc_softc),
};

DRIVER_MODULE(ds13rtc, iicbus, ds13rtc_driver, NULL, NULL);
MODULE_VERSION(ds13rtc, 1);
MODULE_DEPEND(ds13rtc, iicbus, IICBB_MINVER, IICBB_PREFVER, IICBB_MAXVER);
IICBUS_FDT_PNP_INFO(compat_data);