/*      $OpenBSD: ds3231.c,v 1.3 2022/10/15 18:22:53 kettenis Exp $     */
/*
 * Copyright (c) 2020 Mark Kettenis <kettenis@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/device.h>

#include <dev/i2c/i2cvar.h>

#include <dev/clock_subr.h>

#define DS3231_SC               0x00
#define DS3231_MN               0x01
#define DS3231_HR               0x02
#define  DS3231_HR_PM           (1 << 5)
#define  DS3231_HR_12           (1 << 6)
#define  DS3231_HR_12_MASK      ~(DS3231_HR_12 | DS3231_HR_PM)
#define DS3231_DW               0x03
#define DS3231_DT               0x04
#define DS3231_MO               0x05
#define  DS3231_MO_MASK         0x3f
#define DS3231_YR               0x06
#define DS3231_SR               0x07
#define  DS3231_SR_OSF          (1 << 7)

#define DS3231_NRTC_REGS        7

struct dsxrtc_softc {
        struct device sc_dev;
        i2c_tag_t sc_tag;
        i2c_addr_t sc_addr;

        struct todr_chip_handle sc_todr;
};

int     dsxrtc_match(struct device *, void *, void *);
void    dsxrtc_attach(struct device *, struct device *, void *);

const struct cfattach dsxrtc_ca = {
        sizeof(struct dsxrtc_softc), dsxrtc_match, dsxrtc_attach
};

struct cfdriver dsxrtc_cd = {
        NULL, "dsxrtc", DV_DULL
};

uint8_t dsxrtc_reg_read(struct dsxrtc_softc *, int);
void    dsxrtc_reg_write(struct dsxrtc_softc *, int, uint8_t);
int     dsxrtc_clock_read(struct dsxrtc_softc *, struct clock_ymdhms *);
int     dsxrtc_clock_write(struct dsxrtc_softc *, struct clock_ymdhms *);
int     dsxrtc_gettime(struct todr_chip_handle *, struct timeval *);
int     dsxrtc_settime(struct todr_chip_handle *, struct timeval *);

int
dsxrtc_match(struct device *parent, void *match, void *aux)
{
        struct i2c_attach_args *ia = aux;

        if (strcmp(ia->ia_name, "maxim,ds3231") == 0 ||
            strcmp(ia->ia_name, "maxim,ds3232") == 0)
                return 1;

        return 0;
}

void
dsxrtc_attach(struct device *parent, struct device *self, void *aux)
{
        struct dsxrtc_softc *sc = (struct dsxrtc_softc *)self;
        struct i2c_attach_args *ia = aux;

        sc->sc_tag = ia->ia_tag;
        sc->sc_addr = ia->ia_addr;

        sc->sc_todr.cookie = sc;
        sc->sc_todr.todr_gettime = dsxrtc_gettime;
        sc->sc_todr.todr_settime = dsxrtc_settime;
        sc->sc_todr.todr_quality = 1000;
        todr_attach(&sc->sc_todr);

        printf("\n");
}

int
dsxrtc_gettime(struct todr_chip_handle *handle, struct timeval *tv)
{
        struct dsxrtc_softc *sc = handle->cookie;
        struct clock_ymdhms dt;
        int error;

        error = dsxrtc_clock_read(sc, &dt);
        if (error)
                return error;

        if (dt.dt_sec > 59 || dt.dt_min > 59 || dt.dt_hour > 23 ||
            dt.dt_day > 31 || dt.dt_day == 0 ||
            dt.dt_mon > 12 || dt.dt_mon == 0 ||
            dt.dt_year < POSIX_BASE_YEAR)
                return EINVAL;

        tv->tv_sec = clock_ymdhms_to_secs(&dt);
        tv->tv_usec = 0;
        return 0;
}

int
dsxrtc_settime(struct todr_chip_handle *handle, struct timeval *tv)
{
        struct dsxrtc_softc *sc = handle->cookie;
        struct clock_ymdhms dt;

        clock_secs_to_ymdhms(tv->tv_sec, &dt);

        return dsxrtc_clock_write(sc, &dt);

}

uint8_t
dsxrtc_reg_read(struct dsxrtc_softc *sc, int reg)
{
        uint8_t cmd = reg;
        uint8_t val;
        int error;

        iic_acquire_bus(sc->sc_tag, I2C_F_POLL);
        error = iic_exec(sc->sc_tag, I2C_OP_READ_WITH_STOP, sc->sc_addr,
            &cmd, sizeof cmd, &val, sizeof val, I2C_F_POLL);
        iic_release_bus(sc->sc_tag, I2C_F_POLL);

        if (error) {
                printf("%s: can't read register 0x%02x\n",
                    sc->sc_dev.dv_xname, reg);
                val = 0xff;
        }

        return val;
}

void
dsxrtc_reg_write(struct dsxrtc_softc *sc, int reg, uint8_t val)
{
        uint8_t cmd = reg;
        int error;

        iic_acquire_bus(sc->sc_tag, I2C_F_POLL);
        error = iic_exec(sc->sc_tag, I2C_OP_WRITE_WITH_STOP, sc->sc_addr,
            &cmd, sizeof cmd, &val, sizeof val, I2C_F_POLL);
        iic_release_bus(sc->sc_tag, I2C_F_POLL);

        if (error) {
                printf("%s: can't write register 0x%02x\n",
                    sc->sc_dev.dv_xname, reg);
        }
}

int
dsxrtc_clock_read(struct dsxrtc_softc *sc, struct clock_ymdhms *dt)
{
        uint8_t regs[DS3231_NRTC_REGS];
        uint8_t cmd = DS3231_SC;
        uint8_t status;
        int error;

        /* Consider the time to be invalid if the OSF bit is set. */
        status = dsxrtc_reg_read(sc, DS3231_SR);
        if (status & DS3231_SR_OSF)
                return EINVAL;

        iic_acquire_bus(sc->sc_tag, I2C_F_POLL);
        error = iic_exec(sc->sc_tag, I2C_OP_READ_WITH_STOP, sc->sc_addr,
            &cmd, sizeof(cmd), regs, DS3231_NRTC_REGS, I2C_F_POLL);
        iic_release_bus(sc->sc_tag, I2C_F_POLL);

        if (error) {
                printf("%s: can't read RTC\n", sc->sc_dev.dv_xname);
                return error;
        }

        /*
         * Convert the DS3231's register values into something useable.
         */
        dt->dt_sec = FROMBCD(regs[0]);
        dt->dt_min = FROMBCD(regs[1]);
        if (regs[2] & DS3231_HR_12) {
                dt->dt_hour = FROMBCD(regs[2] & DS3231_HR_12_MASK);
                if (regs[2] & DS3231_HR_PM)
                        dt->dt_hour += 12;
        } else {
                dt->dt_hour = FROMBCD(regs[2]);
        }
        dt->dt_day = FROMBCD(regs[4]);
        dt->dt_mon = FROMBCD(regs[5] & DS3231_MO_MASK);
        dt->dt_year = FROMBCD(regs[6]) + 2000;

        return 0;
}

int
dsxrtc_clock_write(struct dsxrtc_softc *sc, struct clock_ymdhms *dt)
{
        uint8_t regs[DS3231_NRTC_REGS];
        uint8_t cmd = DS3231_SC;
        uint8_t status;
        int error;

        /*
         * Convert our time representation into something the DS3231
         * can understand.
         */
        regs[0] = TOBCD(dt->dt_sec);
        regs[1] = TOBCD(dt->dt_min);
        regs[2] = TOBCD(dt->dt_hour);
        regs[3] = TOBCD(dt->dt_wday + 1);
        regs[4] = TOBCD(dt->dt_day);
        regs[5] = TOBCD(dt->dt_mon);
        regs[6] = TOBCD(dt->dt_year - 2000);

        iic_acquire_bus(sc->sc_tag, I2C_F_POLL);
        error = iic_exec(sc->sc_tag, I2C_OP_WRITE_WITH_STOP, sc->sc_addr,
            &cmd, sizeof(cmd), regs, DS3231_NRTC_REGS, I2C_F_POLL);
        iic_release_bus(sc->sc_tag, I2C_F_POLL);

        if (error) {
                printf("%s: can't write RTC\n", sc->sc_dev.dv_xname);
                return error;
        }

        /* Clear OSF flag.  */
        status = dsxrtc_reg_read(sc, DS3231_SR);
        dsxrtc_reg_write(sc, DS3231_SR, status & ~DS3231_SR_OSF);

        return 0;
}