/*      $OpenBSD: gpiodcf.c,v 1.11 2024/05/13 01:15:50 jsg Exp $ */

/*
 * Copyright (c) 2008 Marc Balmer <mbalmer@openbsd.org>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/conf.h>
#include <sys/proc.h>
#include <sys/vnode.h>
#include <sys/device.h>
#include <sys/time.h>
#include <sys/sensors.h>
#include <sys/gpio.h>

#include <dev/gpio/gpiovar.h>

#ifdef GPIODCF_DEBUG
#define DPRINTFN(n, x)  do { if (gpiodcfdebug > (n)) printf x; } while (0)
int gpiodcfdebug = 0;
#else
#define DPRINTFN(n, x)
#endif
#define DPRINTF(x)      DPRINTFN(0, x)

/* max. skew of received time diff vs. measured time diff in percent. */
#define MAX_SKEW        5

#define GPIODCF_NPINS           1
#define GPIODCF_PIN_DATA        0

struct gpiodcf_softc {
        struct device           sc_dev;         /* base device */
        void                    *sc_gpio; 
        struct gpio_pinmap      sc_map;
        int                     __map[GPIODCF_NPINS];
        u_char                  sc_dying;       /* disconnecting */
        int                     sc_data;

        struct timeout          sc_to;

        struct timeout          sc_bv_to;       /* bit-value detect */
        struct timeout          sc_db_to;       /* debounce */
        struct timeout          sc_mg_to;       /* minute-gap detect */
        struct timeout          sc_sl_to;       /* signal-loss detect */
        struct timeout          sc_it_to;       /* invalidate time */

        int                     sc_sync;        /* 1 during sync */
        u_int64_t               sc_mask;        /* 64 bit mask */
        u_int64_t               sc_tbits;       /* Time bits */
        int                     sc_minute;
        int                     sc_level;
        time_t                  sc_last_mg;
        time_t                  sc_current;     /* current time */
        time_t                  sc_next;        /* time to become valid next */
        time_t                  sc_last;
        int                     sc_nrecv;       /* consecutive valid times */
        struct timeval          sc_last_tv;     /* uptime of last valid time */
        struct ksensor          sc_sensor;
#ifdef GPIODCF_DEBUG
        struct ksensor          sc_skew;        /* recv vs local skew */
#endif
        struct ksensordev       sc_sensordev;
};

/*
 * timeouts used:
 */
#define T_BV            150     /* bit value detection (150ms) */
#define T_SYNC          950     /* sync (950ms) */
#define T_MG            1500    /* minute gap detection (1500ms) */
#define T_MGSYNC        450     /* resync after a minute gap (450ms) */
#define T_SL            3000    /* detect signal loss (3sec) */
#define T_WAIT          5000    /* wait (5sec) */
#define T_WARN          300000  /* degrade sensor status to warning (5min) */
#define T_CRIT          900000  /* degrade sensor status to critical (15min) */

void    gpiodcf_probe(void *);
void    gpiodcf_bv_probe(void *);
void    gpiodcf_mg_probe(void *);
void    gpiodcf_sl_probe(void *);
void    gpiodcf_invalidate(void *);

int gpiodcf_match(struct device *, void *, void *); 
void gpiodcf_attach(struct device *, struct device *, void *); 
int gpiodcf_detach(struct device *, int); 
int gpiodcf_activate(struct device *, int); 

int gpiodcf_signal(struct gpiodcf_softc *);

struct cfdriver gpiodcf_cd = {
        NULL, "gpiodcf", DV_DULL
};

const struct cfattach gpiodcf_ca = {
        sizeof(struct gpiodcf_softc),
        gpiodcf_match,
        gpiodcf_attach,
        gpiodcf_detach,
        gpiodcf_activate
};

int
gpiodcf_match(struct device *parent, void *match, void *aux)
{
        struct cfdata *cf = match;
        struct gpio_attach_args *ga = aux;

        if (ga->ga_offset == -1)
                return 0;

        return (strcmp(cf->cf_driver->cd_name, "gpiodcf") == 0);
}

void
gpiodcf_attach(struct device *parent, struct device *self, void *aux)
{
        struct gpiodcf_softc            *sc = (struct gpiodcf_softc *)self;
        struct gpio_attach_args         *ga = aux;
        int                              caps;

        if (gpio_npins(ga->ga_mask) != GPIODCF_NPINS) {
                printf(": invalid pin mask\n");
                return;
        }
        sc->sc_gpio = ga->ga_gpio;
        sc->sc_map.pm_map = sc->__map;
        if (gpio_pin_map(sc->sc_gpio, ga->ga_offset, ga->ga_mask,
            &sc->sc_map)) {
                printf(": can't map pins\n");
                return;
        }

        caps = gpio_pin_caps(sc->sc_gpio, &sc->sc_map, GPIODCF_PIN_DATA);
        if (!(caps & GPIO_PIN_INPUT)) {
                printf(": data pin is unable to receive input\n");
                goto fishy;
        }
        printf(": DATA[%d]", sc->sc_map.pm_map[GPIODCF_PIN_DATA]);
        sc->sc_data = GPIO_PIN_INPUT;
        gpio_pin_ctl(sc->sc_gpio, &sc->sc_map, GPIODCF_PIN_DATA, sc->sc_data);
        printf("\n");

        strlcpy(sc->sc_sensor.desc, "DCF77", sizeof(sc->sc_sensor.desc));

        timeout_set(&sc->sc_to, gpiodcf_probe, sc);
        timeout_set(&sc->sc_bv_to, gpiodcf_bv_probe, sc);
        timeout_set(&sc->sc_mg_to, gpiodcf_mg_probe, sc);
        timeout_set(&sc->sc_sl_to, gpiodcf_sl_probe, sc);
        timeout_set(&sc->sc_it_to, gpiodcf_invalidate, sc);

        strlcpy(sc->sc_sensordev.xname, sc->sc_dev.dv_xname,
            sizeof(sc->sc_sensordev.xname));

        sc->sc_sensor.type = SENSOR_TIMEDELTA;
        sc->sc_sensor.status = SENSOR_S_UNKNOWN;
        sensor_attach(&sc->sc_sensordev, &sc->sc_sensor);

#ifdef GPIODCF_DEBUG
        sc->sc_skew.type = SENSOR_TIMEDELTA;
        sc->sc_skew.status = SENSOR_S_UNKNOWN;
        strlcpy(sc->sc_skew.desc, "local clock skew",
            sizeof(sc->sc_skew.desc));
        sensor_attach(&sc->sc_sensordev, &sc->sc_skew);
#endif
        sensordev_install(&sc->sc_sensordev);

        sc->sc_level = 0;
        sc->sc_minute = 0;
        sc->sc_last_mg = 0L;

        sc->sc_sync = 1;

        sc->sc_current = 0L;
        sc->sc_next = 0L;
        sc->sc_nrecv = 0;
        sc->sc_last = 0L;
        sc->sc_last_tv.tv_sec = 0L;

        /* Give the receiver some slack to stabilize */
        timeout_add_msec(&sc->sc_to, T_WAIT);

        /* Detect signal loss */
        timeout_add_msec(&sc->sc_sl_to, T_WAIT + T_SL);

        DPRINTF(("synchronizing\n"));
        return;

fishy:
        DPRINTF(("gpiodcf_attach failed\n"));
        gpio_pin_unmap(sc->sc_gpio, &sc->sc_map);
        sc->sc_dying = 1;
}

int
gpiodcf_detach(struct device *self, int flags)
{
        struct gpiodcf_softc    *sc = (struct gpiodcf_softc *)self;

        sc->sc_dying = 1;

        timeout_del(&sc->sc_to);
        timeout_del(&sc->sc_bv_to);
        timeout_del(&sc->sc_mg_to);
        timeout_del(&sc->sc_sl_to);
        timeout_del(&sc->sc_it_to);

        /* Unregister the clock with the kernel */
        sensordev_deinstall(&sc->sc_sensordev);

        /* Finally unmap the GPIO pin */
        gpio_pin_unmap(sc->sc_gpio, &sc->sc_map);

        return 0;
}

/*
 * return 1 during high-power-, 0 during low-power-emission
 * If bit 0 is set, the transmitter emits at full power.
 * During the low-power emission we decode a zero bit.
 */
int
gpiodcf_signal(struct gpiodcf_softc *sc)
{
        return (gpio_pin_read(sc->sc_gpio, &sc->sc_map, GPIODCF_PIN_DATA) ==
            GPIO_PIN_HIGH ? 1 : 0);
}

/* gpiodcf_probe runs in a process context. */
void
gpiodcf_probe(void *xsc)
{
        struct gpiodcf_softc    *sc = xsc;
        struct timespec          now;
        int                      data;

        if (sc->sc_dying)
                return;

        data = gpiodcf_signal(sc);
        if (data == -1)
                return;

        if (data) {
                sc->sc_level = 1;
                timeout_add(&sc->sc_to, 1);
                return;
        }

        if (sc->sc_level == 0)
                return;

        /* the beginning of a second */
        sc->sc_level = 0;
        if (sc->sc_minute == 1) {
                if (sc->sc_sync) {
                        DPRINTF(("start collecting bits\n"));
                        sc->sc_sync = 0;
                } else {
                        /* provide the timedelta */
                        microtime(&sc->sc_sensor.tv);
                        nanotime(&now);
                        sc->sc_current = sc->sc_next;
                        sc->sc_sensor.value = (int64_t)(now.tv_sec -
                            sc->sc_current) * 1000000000LL + now.tv_nsec;

                        sc->sc_sensor.status = SENSOR_S_OK;

                        /*
                         * if no valid time information is received
                         * during the next 5 minutes, the sensor state
                         * will be degraded to SENSOR_S_WARN
                         */
                        timeout_add_msec(&sc->sc_it_to, T_WARN);
                }
                sc->sc_minute = 0;
        }

        timeout_add_msec(&sc->sc_to, T_SYNC);   /* resync in 950 ms */

        /* no clock and bit detection during sync */
        if (!sc->sc_sync) {
                /* detect bit value */
                timeout_add_msec(&sc->sc_bv_to, T_BV);
        }
        timeout_add_msec(&sc->sc_mg_to, T_MG);  /* detect minute gap */
        timeout_add_msec(&sc->sc_sl_to, T_SL);  /* detect signal loss */
}

/* detect the bit value */
void
gpiodcf_bv_probe(void *xsc)
{
        struct gpiodcf_softc    *sc = xsc;
        int                      data;

        if (sc->sc_dying)
                return;

        data = gpiodcf_signal(sc);
        if (data == -1) {
                DPRINTF(("bit detection failed\n"));
                return;
        }       

        DPRINTFN(1, (data ? "0" : "1"));
        if (!(data))
                sc->sc_tbits |= sc->sc_mask;
        sc->sc_mask <<= 1;
}

/* detect the minute gap */
void
gpiodcf_mg_probe(void *xsc)
{
        struct gpiodcf_softc    *sc = xsc;
        struct clock_ymdhms      ymdhm;
        struct timeval           monotime;
        int                      tdiff_recv, tdiff_local;
        int                      skew;
        int                      minute_bits, hour_bits, day_bits;
        int                      month_bits, year_bits, wday;
        int                      p1, p2, p3;
        int                      p1_bit, p2_bit, p3_bit;
        int                      r_bit, a1_bit, a2_bit, z1_bit, z2_bit;
        int                      s_bit, m_bit;
        u_int32_t                parity = 0x6996;

        if (sc->sc_sync) {
                sc->sc_minute = 1;
                goto cleanbits;
        }

        if (gettime() - sc->sc_last_mg < 57) {
                DPRINTF(("\nunexpected gap, resync\n"));
                sc->sc_sync = sc->sc_minute = 1;
                goto cleanbits; 
        }

        /* extract bits w/o parity */
        m_bit = sc->sc_tbits & 1;
        r_bit = sc->sc_tbits >> 15 & 1;
        a1_bit = sc->sc_tbits >> 16 & 1;
        z1_bit = sc->sc_tbits >> 17 & 1;
        z2_bit = sc->sc_tbits >> 18 & 1;
        a2_bit = sc->sc_tbits >> 19 & 1;
        s_bit = sc->sc_tbits >> 20 & 1;
        p1_bit = sc->sc_tbits >> 28 & 1;
        p2_bit = sc->sc_tbits >> 35 & 1;
        p3_bit = sc->sc_tbits >> 58 & 1;

        minute_bits = sc->sc_tbits >> 21 & 0x7f;        
        hour_bits = sc->sc_tbits >> 29 & 0x3f;
        day_bits = sc->sc_tbits >> 36 & 0x3f;
        wday = (sc->sc_tbits >> 42) & 0x07;
        month_bits = sc->sc_tbits >> 45 & 0x1f;
        year_bits = sc->sc_tbits >> 50 & 0xff;

        /* validate time information */
        p1 = (parity >> (minute_bits & 0x0f) & 1) ^
            (parity >> (minute_bits >> 4) & 1);

        p2 = (parity >> (hour_bits & 0x0f) & 1) ^
            (parity >> (hour_bits >> 4) & 1);

        p3 = (parity >> (day_bits & 0x0f) & 1) ^
            (parity >> (day_bits >> 4) & 1) ^
            ((parity >> wday) & 1) ^ (parity >> (month_bits & 0x0f) & 1) ^
            (parity >> (month_bits >> 4) & 1) ^
            (parity >> (year_bits & 0x0f) & 1) ^
            (parity >> (year_bits >> 4) & 1);

        if (m_bit == 0 && s_bit == 1 && p1 == p1_bit && p2 == p2_bit &&
            p3 == p3_bit && (z1_bit ^ z2_bit)) {

                /* Decode time */
                if ((ymdhm.dt_year = 2000 + FROMBCD(year_bits)) > 2037) {
                        DPRINTF(("year out of range, resync\n"));
                        sc->sc_sync = 1;
                        goto cleanbits;
                }
                ymdhm.dt_min = FROMBCD(minute_bits);
                ymdhm.dt_hour = FROMBCD(hour_bits);
                ymdhm.dt_day = FROMBCD(day_bits);
                ymdhm.dt_mon = FROMBCD(month_bits);
                ymdhm.dt_sec = 0;

                sc->sc_next = clock_ymdhms_to_secs(&ymdhm);
                getmicrouptime(&monotime);

                /* convert to coordinated universal time */
                sc->sc_next -= z1_bit ? 7200 : 3600;

                DPRINTF(("\n%02d.%02d.%04d %02d:%02d:00 %s",
                    ymdhm.dt_day, ymdhm.dt_mon, ymdhm.dt_year,
                    ymdhm.dt_hour, ymdhm.dt_min, z1_bit ? "CEST" : "CET"));
                DPRINTF((r_bit ? ", call bit" : ""));
                DPRINTF((a1_bit ? ", dst chg ann." : ""));
                DPRINTF((a2_bit ? ", leap sec ann." : ""));
                DPRINTF(("\n"));

                if (sc->sc_last) {
                        tdiff_recv = sc->sc_next - sc->sc_last;
                        tdiff_local = monotime.tv_sec - sc->sc_last_tv.tv_sec;
                        skew = abs(tdiff_local - tdiff_recv);
#ifdef GPIODCF_DEBUG
                        if (sc->sc_skew.status == SENSOR_S_UNKNOWN)
                                sc->sc_skew.status = SENSOR_S_CRIT;
                        sc->sc_skew.value = skew * 1000000000LL;
                        getmicrotime(&sc->sc_skew.tv);
#endif
                        DPRINTF(("local = %d, recv = %d, skew = %d\n",
                            tdiff_local, tdiff_recv, skew));

                        if (skew && skew * 100LL / tdiff_local > MAX_SKEW) {
                                DPRINTF(("skew out of tolerated range\n"));
                                goto cleanbits;
                        } else {
                                if (sc->sc_nrecv < 2) {
                                        sc->sc_nrecv++;
                                        DPRINTF(("got frame %d\n",
                                            sc->sc_nrecv));
                                } else {
                                        DPRINTF(("data is valid\n"));
                                        sc->sc_minute = 1;
                                }
                        }
                } else {
                        DPRINTF(("received the first frame\n"));
                        sc->sc_nrecv = 1;
                }

                /* record the time received and when it was received */
                sc->sc_last = sc->sc_next;
                sc->sc_last_tv.tv_sec = monotime.tv_sec;
        } else {
                DPRINTF(("\nparity error, resync\n"));
                sc->sc_sync = sc->sc_minute = 1;
        }

cleanbits:
        timeout_add_msec(&sc->sc_to, T_MGSYNC); /* re-sync in 450 ms */
        sc->sc_last_mg = gettime();
        sc->sc_tbits = 0LL;
        sc->sc_mask = 1LL;
}

/* detect signal loss */
void
gpiodcf_sl_probe(void *xsc)
{
        struct gpiodcf_softc *sc = xsc;

        if (sc->sc_dying)
                return;

        DPRINTF(("no signal\n"));
        sc->sc_sync = 1;
        timeout_add_msec(&sc->sc_to, T_WAIT);
        timeout_add_msec(&sc->sc_sl_to, T_WAIT + T_SL);
}

/* invalidate timedelta (called in an interrupt context) */
void
gpiodcf_invalidate(void *xsc)
{
        struct gpiodcf_softc *sc = xsc;

        if (sc->sc_dying)
                return;

        if (sc->sc_sensor.status == SENSOR_S_OK) {
                sc->sc_sensor.status = SENSOR_S_WARN;
                /*
                 * further degrade in 15 minutes if we dont receive any new
                 * time information
                 */
                timeout_add_msec(&sc->sc_it_to, T_CRIT);
        } else {
                sc->sc_sensor.status = SENSOR_S_CRIT;
                sc->sc_nrecv = 0;
        }
}

int
gpiodcf_activate(struct device *self, int act)
{
        struct gpiodcf_softc *sc = (struct gpiodcf_softc *)self;

        switch (act) {
        case DVACT_DEACTIVATE:
                sc->sc_dying = 1;
                break;
        }
        return 0;
}