/*      $NetBSD: s390.c,v 1.7 2021/01/30 17:38:57 thorpej Exp $ */

/*-
* Copyright (c) 2011 Frank Wille.
* All rights reserved.
*
* Written by Frank Wille for The NetBSD Project.
*
* 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 NETBSD FOUNDATION, INC. 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 FOUNDATION 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>
__KERNEL_RCSID(0, "$NetBSD: s390.c,v 1.7 2021/01/30 17:38:57 thorpej Exp $");

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/device.h>
#include <sys/conf.h>

#include <dev/clock_subr.h>

#include <dev/i2c/i2cvar.h>
#include <dev/i2c/s390reg.h>

struct s390rtc_softc {
       device_t sc_dev;
       i2c_tag_t sc_tag;
       i2c_addr_t sc_addr;
       struct todr_chip_handle sc_todr;
};

static int s390rtc_match(device_t, cfdata_t, void *);
static void s390rtc_attach(device_t, device_t, void *);

CFATTACH_DECL_NEW(s390rtc, sizeof(struct s390rtc_softc),
   s390rtc_match, s390rtc_attach, NULL, NULL);

static int s390rtc_gettime_ymdhms(struct todr_chip_handle *,
                                 struct clock_ymdhms *);
static int s390rtc_settime_ymdhms(struct todr_chip_handle *,
                                 struct clock_ymdhms *);
static int s390rtc_read(struct s390rtc_softc *, int, uint8_t *, size_t);
static int s390rtc_write(struct s390rtc_softc *, int, uint8_t *, size_t);
static uint8_t bitreverse(uint8_t);

static const struct device_compatible_entry compat_data[] = {
       { .compat = "sii,s35390a" },
       DEVICE_COMPAT_EOL
};

static int
s390rtc_match(device_t parent, cfdata_t cf, void *arg)
{
       struct i2c_attach_args *ia = arg;
       int match_result;

       if (iic_use_direct_match(ia, cf, compat_data, &match_result))
               return match_result;

       /* indirect config - check typical address */
       if (ia->ia_addr == S390_ADDR)
               return I2C_MATCH_ADDRESS_ONLY;

       return 0;
}

static void
s390rtc_attach(device_t parent, device_t self, void *arg)
{
       struct s390rtc_softc *sc = device_private(self);
       struct i2c_attach_args *ia = arg;
       uint8_t reg[1];

       aprint_naive(": Real-time Clock\n");
       aprint_normal(": Seiko Instruments 35390A Real-time Clock\n");

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

       /* Reset the chip and turn on 24h mode, after power-off or battery. */
       if (s390rtc_read(sc, S390_STATUS1, reg, sizeof(reg)))
               return;
       if (reg[0] & (S390_ST1_POC | S390_ST1_BLD)) {
               reg[0] |= S390_ST1_24H | S390_ST1_RESET;
               if (s390rtc_write(sc, S390_STATUS1, reg, sizeof(reg)))
                       return;
       }

       /* Disable the test mode, when enabled. */
       if (s390rtc_read(sc, S390_STATUS2, reg, sizeof(reg)))
               return;
       if ((reg[0] & S390_ST2_TEST)) {
               reg[0] &= ~S390_ST2_TEST;
               if (s390rtc_write(sc, S390_STATUS2, reg, sizeof(reg)))
                       return;
       }

       sc->sc_todr.cookie = sc;
       sc->sc_todr.todr_gettime = NULL;
       sc->sc_todr.todr_settime = NULL;
       sc->sc_todr.todr_gettime_ymdhms = s390rtc_gettime_ymdhms;
       sc->sc_todr.todr_settime_ymdhms = s390rtc_settime_ymdhms;
       sc->sc_todr.todr_setwen = NULL;
       todr_attach(&sc->sc_todr);
}

static int
s390rtc_gettime_ymdhms(struct todr_chip_handle *ch, struct clock_ymdhms *dt)
{
       struct s390rtc_softc *sc = ch->cookie;
       uint8_t bcd[S390_RT1_NBYTES];
       int error;

       if ((error = s390rtc_read(sc, S390_REALTIME1, bcd,
                                 S390_RT1_NBYTES)) != 0)
               return error;

       /*
        * Convert the register values into something useable.
        */
       dt->dt_sec = bcdtobin(bcd[S390_RT1_SECOND]);
       dt->dt_min = bcdtobin(bcd[S390_RT1_MINUTE]);
       dt->dt_hour = bcdtobin(bcd[S390_RT1_HOUR] & 0x3f);
       dt->dt_day = bcdtobin(bcd[S390_RT1_DAY]);
       dt->dt_mon = bcdtobin(bcd[S390_RT1_MONTH]);
       dt->dt_year = bcdtobin(bcd[S390_RT1_YEAR]) + 2000;

       return 0;
}

static int
s390rtc_settime_ymdhms(struct todr_chip_handle *ch, struct clock_ymdhms *dt)
{
       struct s390rtc_softc *sc = ch->cookie;
       uint8_t bcd[S390_RT1_NBYTES];

       /*
        * Convert our time representation into something the S-xx390
        * can understand.
        */
       bcd[S390_RT1_SECOND] = bintobcd(dt->dt_sec);
       bcd[S390_RT1_MINUTE] = bintobcd(dt->dt_min);
       bcd[S390_RT1_HOUR] = bintobcd(dt->dt_hour);
       bcd[S390_RT1_DAY] = bintobcd(dt->dt_day);
       bcd[S390_RT1_WDAY] = bintobcd(dt->dt_wday);
       bcd[S390_RT1_MONTH] = bintobcd(dt->dt_mon);
       bcd[S390_RT1_YEAR] = bintobcd(dt->dt_year % 100);

       return s390rtc_write(sc, S390_REALTIME1, bcd, S390_RT1_NBYTES);
}

static int
s390rtc_read(struct s390rtc_softc *sc, int reg, uint8_t *buf, size_t len)
{
       int i, error;

       if ((error = iic_acquire_bus(sc->sc_tag, 0)) != 0) {
               aprint_error_dev(sc->sc_dev,
                   "%s: failed to acquire I2C bus\n", __func__);
               return error;
       }

       if ((error = iic_exec(sc->sc_tag, I2C_OP_READ_WITH_STOP,
                             sc->sc_addr + reg, NULL, 0, buf, len, 0)) != 0) {
               iic_release_bus(sc->sc_tag, 0);
               aprint_error_dev(sc->sc_dev,
                   "%s: failed to read reg%d\n", __func__, reg);
               return error;
       }

       iic_release_bus(sc->sc_tag, 0);

       /* this chip returns each byte in reverse order */
       for (i = 0; i < len; i++)
               buf[i] = bitreverse(buf[i]);

       return 0;
}

static int
s390rtc_write(struct s390rtc_softc *sc, int reg, uint8_t *buf, size_t len)
{
       int i, error;

       if ((error = iic_acquire_bus(sc->sc_tag, 0)) != 0) {
               aprint_error_dev(sc->sc_dev,
                   "%s: failed to acquire I2C bus\n", __func__);
               return error;
       }

       /* this chip expects each byte in reverse order */
       for (i = 0; i < len; i++)
               buf[i] = bitreverse(buf[i]);

       if ((error = iic_exec(sc->sc_tag, I2C_OP_WRITE_WITH_STOP,
                             sc->sc_addr + reg, NULL, 0, buf, len, 0)) != 0) {
               iic_release_bus(sc->sc_tag, 0);
               aprint_error_dev(sc->sc_dev,
                   "%s: failed to write reg%d\n", __func__, reg);
               return error;
       }

       iic_release_bus(sc->sc_tag, 0);
       return 0;
}

static uint8_t
bitreverse(uint8_t x)
{
       static unsigned char nibbletab[16] = {
               0, 8, 4, 12, 2, 10, 6, 14, 1, 9, 5, 13, 3, 11, 7, 15
       };

       return (nibbletab[x & 15] << 4) | nibbletab[x >> 4];
}

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