/*      $OpenBSD: owtemp.c,v 1.18 2022/04/06 18:59:29 naddy Exp $       */

/*
 * Copyright (c) 2006, 2009 Alexander Yurchenko <grange@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.
 */

/*
 * 1-Wire temperature family type device driver.
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/device.h>
#include <sys/kernel.h>
#include <sys/rwlock.h>
#include <sys/sensors.h>

#include <dev/onewire/onewiredevs.h>
#include <dev/onewire/onewirereg.h>
#include <dev/onewire/onewirevar.h>

/* Commands */
#define DS1920_CMD_CONVERT              0x44
#define DS1920_CMD_READ_SCRATCHPAD      0xbe

/* Scratchpad layout */
#define DS1920_SP_TEMP_LSB              0
#define DS1920_SP_TEMP_MSB              1
#define DS1920_SP_TH                    2
#define DS1920_SP_TL                    3
#define DS18B20_SP_CONFIG               4
#define DS1920_SP_COUNT_REMAIN          6
#define DS1920_SP_COUNT_PERC            7
#define DS1920_SP_CRC                   8

struct owtemp_softc {
        struct device           sc_dev;

        void *                  sc_onewire;
        u_int64_t               sc_rom;

        struct ksensor          sc_sensor;
        struct ksensordev       sc_sensordev;
        struct sensor_task      *sc_sensortask;
        struct rwlock           sc_lock;
};

int     owtemp_match(struct device *, void *, void *);
void    owtemp_attach(struct device *, struct device *, void *);
int     owtemp_detach(struct device *, int);
int     owtemp_activate(struct device *, int);

void    owtemp_update(void *);

const struct cfattach owtemp_ca = {
        sizeof(struct owtemp_softc),
        owtemp_match,
        owtemp_attach,
        owtemp_detach,
        owtemp_activate
};

struct cfdriver owtemp_cd = {
        NULL, "owtemp", DV_DULL
};

static const struct onewire_matchfam owtemp_fams[] = {
        { ONEWIRE_FAMILY_DS1920 },
        { ONEWIRE_FAMILY_DS18B20 },
        { ONEWIRE_FAMILY_DS1822 }
};

int
owtemp_match(struct device *parent, void *match, void *aux)
{
        return (onewire_matchbyfam(aux, owtemp_fams, nitems(owtemp_fams)));
}

void
owtemp_attach(struct device *parent, struct device *self, void *aux)
{
        struct owtemp_softc *sc = (struct owtemp_softc *)self;
        struct onewire_attach_args *oa = aux;

        sc->sc_onewire = oa->oa_onewire;
        sc->sc_rom = oa->oa_rom;

        /* Initialize sensor */
        strlcpy(sc->sc_sensordev.xname, sc->sc_dev.dv_xname,
            sizeof(sc->sc_sensordev.xname));
        sc->sc_sensor.type = SENSOR_TEMP;
        snprintf(sc->sc_sensor.desc, sizeof(sc->sc_sensor.desc), "sn %012llx",
            ONEWIRE_ROM_SN(oa->oa_rom));

        sc->sc_sensortask = sensor_task_register(sc, owtemp_update, 5);
        if (sc->sc_sensortask == NULL) {
                printf(": unable to register update task\n");
                return;
        }
        sensor_attach(&sc->sc_sensordev, &sc->sc_sensor);
        sensordev_install(&sc->sc_sensordev);

        rw_init(&sc->sc_lock, sc->sc_dev.dv_xname);
        printf("\n");
}

int
owtemp_detach(struct device *self, int flags)
{
        struct owtemp_softc *sc = (struct owtemp_softc *)self;

        rw_enter_write(&sc->sc_lock);
        sensordev_deinstall(&sc->sc_sensordev);
        if (sc->sc_sensortask != NULL)
                sensor_task_unregister(sc->sc_sensortask);
        rw_exit_write(&sc->sc_lock);

        return (0);
}

int
owtemp_activate(struct device *self, int act)
{
        return (0);
}

void
owtemp_update(void *arg)
{
        struct owtemp_softc *sc = arg;
        u_int8_t data[9];
        int16_t temp;
        int count_perc, count_remain, val;

        rw_enter_write(&sc->sc_lock);
        onewire_lock(sc->sc_onewire, 0);
        if (onewire_reset(sc->sc_onewire) != 0)
                goto done;
        onewire_matchrom(sc->sc_onewire, sc->sc_rom);

        /*
         * Start temperature conversion. The conversion takes up to 750ms.
         * After sending the command, the data line must be held high for
         * at least 750ms to provide power during the conversion process.
         * As such, no other activity may take place on the 1-Wire bus for
         * at least this period.
         */
        onewire_write_byte(sc->sc_onewire, DS1920_CMD_CONVERT);
        tsleep_nsec(sc, PRIBIO, "owtemp", SEC_TO_NSEC(1));

        if (onewire_reset(sc->sc_onewire) != 0)
                goto done;
        onewire_matchrom(sc->sc_onewire, sc->sc_rom);

        /*
         * The result of the temperature measurement is placed in the
         * first two bytes of the scratchpad.
         */
        onewire_write_byte(sc->sc_onewire, DS1920_CMD_READ_SCRATCHPAD);
        onewire_read_block(sc->sc_onewire, data, 9);
        if (onewire_crc(data, 8) == data[DS1920_SP_CRC]) {
                temp = data[DS1920_SP_TEMP_MSB] << 8 |
                    data[DS1920_SP_TEMP_LSB];
                if (ONEWIRE_ROM_FAMILY(sc->sc_rom) == ONEWIRE_FAMILY_DS18B20 ||
                    ONEWIRE_ROM_FAMILY(sc->sc_rom) == ONEWIRE_FAMILY_DS1822) {
                        /*
                         * DS18B20 decoding
                         * default 12 bit 0.0625 C resolution
                         */
                        val = temp * (1000000 / 16);
                } else {
                        /* DS1920 decoding */
                        count_perc = data[DS1920_SP_COUNT_PERC];
                        count_remain = data[DS1920_SP_COUNT_REMAIN];

                        if (count_perc != 0) {
                                /* High resolution algorithm */
                                temp &= ~0x0001;
                                val = temp * 500000 - 250000 +
                                    ((count_perc - count_remain) * 1000000) /
                                    count_perc;
                        } else {
                                val = temp * 500000;
                        }
                }
                sc->sc_sensor.value = 273150000 + val;
        }

done:
        onewire_unlock(sc->sc_onewire);
        rw_exit_write(&sc->sc_lock);
}