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ds1307.c revision 1.25.2.1
      1 /*	$NetBSD: ds1307.c,v 1.25.2.1 2018/06/25 07:25:50 pgoyette Exp $	*/
      2 
      3 /*
      4  * Copyright (c) 2003 Wasabi Systems, Inc.
      5  * All rights reserved.
      6  *
      7  * Written by Steve C. Woodford and Jason R. Thorpe for Wasabi Systems, Inc.
      8  *
      9  * Redistribution and use in source and binary forms, with or without
     10  * modification, are permitted provided that the following conditions
     11  * are met:
     12  * 1. Redistributions of source code must retain the above copyright
     13  *    notice, this list of conditions and the following disclaimer.
     14  * 2. Redistributions in binary form must reproduce the above copyright
     15  *    notice, this list of conditions and the following disclaimer in the
     16  *    documentation and/or other materials provided with the distribution.
     17  * 3. All advertising materials mentioning features or use of this software
     18  *    must display the following acknowledgement:
     19  *      This product includes software developed for the NetBSD Project by
     20  *      Wasabi Systems, Inc.
     21  * 4. The name of Wasabi Systems, Inc. may not be used to endorse
     22  *    or promote products derived from this software without specific prior
     23  *    written permission.
     24  *
     25  * THIS SOFTWARE IS PROVIDED BY WASABI SYSTEMS, INC. ``AS IS'' AND
     26  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     27  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     28  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL WASABI SYSTEMS, INC
     29  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     30  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     31  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     32  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     33  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     34  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     35  * POSSIBILITY OF SUCH DAMAGE.
     36  */
     37 
     38 #include <sys/cdefs.h>
     39 __KERNEL_RCSID(0, "$NetBSD: ds1307.c,v 1.25.2.1 2018/06/25 07:25:50 pgoyette Exp $");
     40 
     41 #include <sys/param.h>
     42 #include <sys/systm.h>
     43 #include <sys/device.h>
     44 #include <sys/kernel.h>
     45 #include <sys/fcntl.h>
     46 #include <sys/uio.h>
     47 #include <sys/conf.h>
     48 #include <sys/event.h>
     49 
     50 #include <dev/clock_subr.h>
     51 
     52 #include <dev/i2c/i2cvar.h>
     53 #include <dev/i2c/ds1307reg.h>
     54 #include <dev/sysmon/sysmonvar.h>
     55 
     56 #include "ioconf.h"
     57 
     58 struct dsrtc_model {
     59 	const i2c_addr_t *dm_valid_addrs;
     60 	uint16_t dm_model;
     61 	uint8_t dm_ch_reg;
     62 	uint8_t dm_ch_value;
     63 	uint8_t dm_vbaten_reg;
     64 	uint8_t dm_vbaten_value;
     65 	uint8_t dm_rtc_start;
     66 	uint8_t dm_rtc_size;
     67 	uint8_t dm_nvram_start;
     68 	uint8_t dm_nvram_size;
     69 	uint8_t dm_flags;
     70 #define	DSRTC_FLAG_CLOCK_HOLD		0x01
     71 #define	DSRTC_FLAG_BCD			0x02
     72 #define	DSRTC_FLAG_TEMP			0x04
     73 #define DSRTC_FLAG_VBATEN		0x08
     74 #define	DSRTC_FLAG_YEAR_START_2K	0x10
     75 #define	DSRTC_FLAG_CLOCK_HOLD_REVERSED	0x20
     76 };
     77 
     78 static const char *ds1307_compats[] = { "dallas,ds1307", "maxim,ds1307", NULL };
     79 static const i2c_addr_t ds1307_valid_addrs[] = { DS1307_ADDR, 0 };
     80 static const struct dsrtc_model ds1307_model = {
     81 	.dm_valid_addrs = ds1307_valid_addrs,
     82 	.dm_model = 1307,
     83 	.dm_ch_reg = DSXXXX_SECONDS,
     84 	.dm_ch_value = DS1307_SECONDS_CH,
     85 	.dm_rtc_start = DS1307_RTC_START,
     86 	.dm_rtc_size = DS1307_RTC_SIZE,
     87 	.dm_nvram_start = DS1307_NVRAM_START,
     88 	.dm_nvram_size = DS1307_NVRAM_SIZE,
     89 	.dm_flags = DSRTC_FLAG_BCD | DSRTC_FLAG_CLOCK_HOLD,
     90 };
     91 
     92 static const char *ds1339_compats[] = { "dallas,ds1339", "maxim,ds1339", NULL };
     93 static const struct dsrtc_model ds1339_model = {
     94 	.dm_valid_addrs = ds1307_valid_addrs,
     95 	.dm_model = 1339,
     96 	.dm_rtc_start = DS1339_RTC_START,
     97 	.dm_rtc_size = DS1339_RTC_SIZE,
     98 	.dm_flags = DSRTC_FLAG_BCD,
     99 };
    100 
    101 static const char *ds1340_compats[] = { "dallas,ds1340", "maxim,ds1340", NULL };
    102 static const struct dsrtc_model ds1340_model = {
    103 	.dm_valid_addrs = ds1307_valid_addrs,
    104 	.dm_model = 1340,
    105 	.dm_ch_reg = DSXXXX_SECONDS,
    106 	.dm_ch_value = DS1340_SECONDS_EOSC,
    107 	.dm_rtc_start = DS1340_RTC_START,
    108 	.dm_rtc_size = DS1340_RTC_SIZE,
    109 	.dm_flags = DSRTC_FLAG_BCD,
    110 };
    111 
    112 static const char *ds1672_compats[] = { "dallas,ds1672", "maxim,ds1672", NULL };
    113 static const struct dsrtc_model ds1672_model = {
    114 	.dm_valid_addrs = ds1307_valid_addrs,
    115 	.dm_model = 1672,
    116 	.dm_rtc_start = DS1672_RTC_START,
    117 	.dm_rtc_size = DS1672_RTC_SIZE,
    118 	.dm_ch_reg = DS1672_CONTROL,
    119 	.dm_ch_value = DS1672_CONTROL_CH,
    120 	.dm_flags = 0,
    121 };
    122 
    123 static const char *ds3231_compats[] = { "dallas,ds3231", "maxim,ds3231", NULL };
    124 static const struct dsrtc_model ds3231_model = {
    125 	.dm_valid_addrs = ds1307_valid_addrs,
    126 	.dm_model = 3231,
    127 	.dm_rtc_start = DS3232_RTC_START,
    128 	.dm_rtc_size = DS3232_RTC_SIZE,
    129 	.dm_flags = DSRTC_FLAG_BCD | DSRTC_FLAG_TEMP,
    130 };
    131 
    132 static const char *ds3232_compats[] = { "dallas,ds3232", "maxim,ds3232", NULL };
    133 static const struct dsrtc_model ds3232_model = {
    134 	.dm_valid_addrs = ds1307_valid_addrs,
    135 	.dm_model = 3232,
    136 	.dm_rtc_start = DS3232_RTC_START,
    137 	.dm_rtc_size = DS3232_RTC_SIZE,
    138 	.dm_nvram_start = DS3232_NVRAM_START,
    139 	.dm_nvram_size = DS3232_NVRAM_SIZE,
    140 	/*
    141 	 * XXX
    142 	 * the DS3232 likely has the temperature sensor too but I can't
    143 	 * easily verify or test that right now
    144 	 */
    145 	.dm_flags = DSRTC_FLAG_BCD,
    146 };
    147 
    148 				/* XXX vendor prefix */
    149 static const char *mcp7940_compats[] = { "microchip,mcp7940", NULL };
    150 static const i2c_addr_t mcp7940_valid_addrs[] = { MCP7940_ADDR, 0 };
    151 static const struct dsrtc_model mcp7940_model = {
    152 	.dm_valid_addrs = mcp7940_valid_addrs,
    153 	.dm_model = 7940,
    154 	.dm_rtc_start = DS1307_RTC_START,
    155 	.dm_rtc_size = DS1307_RTC_SIZE,
    156 	.dm_ch_reg = DSXXXX_SECONDS,
    157 	.dm_ch_value = DS1307_SECONDS_CH,
    158 	.dm_vbaten_reg = DSXXXX_DAY,
    159 	.dm_vbaten_value = MCP7940_TOD_DAY_VBATEN,
    160 	.dm_nvram_start = MCP7940_NVRAM_START,
    161 	.dm_nvram_size = MCP7940_NVRAM_SIZE,
    162 	.dm_flags = DSRTC_FLAG_BCD | DSRTC_FLAG_CLOCK_HOLD |
    163 		DSRTC_FLAG_VBATEN | DSRTC_FLAG_CLOCK_HOLD_REVERSED,
    164 };
    165 
    166 static const struct device_compatible_entry dsrtc_compat_data[] = {
    167 	DEVICE_COMPAT_ENTRY_WITH_DATA(ds1307_compats,  &ds1307_model),
    168 	DEVICE_COMPAT_ENTRY_WITH_DATA(ds1339_compats,  &ds1339_model),
    169 	DEVICE_COMPAT_ENTRY_WITH_DATA(ds1340_compats,  &ds1340_model),
    170 	DEVICE_COMPAT_ENTRY_WITH_DATA(ds1672_compats,  &ds1672_model),
    171 	DEVICE_COMPAT_ENTRY_WITH_DATA(ds3231_compats,  &ds3231_model),
    172 	DEVICE_COMPAT_ENTRY_WITH_DATA(ds3232_compats,  &ds3232_model),
    173 	DEVICE_COMPAT_ENTRY_WITH_DATA(mcp7940_compats, &mcp7940_model),
    174 	DEVICE_COMPAT_TERMINATOR
    175 };
    176 
    177 struct dsrtc_softc {
    178 	device_t sc_dev;
    179 	i2c_tag_t sc_tag;
    180 	uint8_t sc_address;
    181 	bool sc_open;
    182 	struct dsrtc_model sc_model;
    183 	struct todr_chip_handle sc_todr;
    184 	struct sysmon_envsys *sc_sme;
    185 	envsys_data_t sc_sensor;
    186 };
    187 
    188 static void	dsrtc_attach(device_t, device_t, void *);
    189 static int	dsrtc_match(device_t, cfdata_t, void *);
    190 
    191 CFATTACH_DECL_NEW(dsrtc, sizeof(struct dsrtc_softc),
    192     dsrtc_match, dsrtc_attach, NULL, NULL);
    193 
    194 dev_type_open(dsrtc_open);
    195 dev_type_close(dsrtc_close);
    196 dev_type_read(dsrtc_read);
    197 dev_type_write(dsrtc_write);
    198 
    199 const struct cdevsw dsrtc_cdevsw = {
    200 	.d_open = dsrtc_open,
    201 	.d_close = dsrtc_close,
    202 	.d_read = dsrtc_read,
    203 	.d_write = dsrtc_write,
    204 	.d_ioctl = noioctl,
    205 	.d_stop = nostop,
    206 	.d_tty = notty,
    207 	.d_poll = nopoll,
    208 	.d_mmap = nommap,
    209 	.d_kqfilter = nokqfilter,
    210 	.d_discard = nodiscard,
    211 	.d_flag = D_OTHER
    212 };
    213 
    214 static int dsrtc_gettime_ymdhms(struct todr_chip_handle *, struct clock_ymdhms *);
    215 static int dsrtc_settime_ymdhms(struct todr_chip_handle *, struct clock_ymdhms *);
    216 static int dsrtc_clock_read_ymdhms(struct dsrtc_softc *, struct clock_ymdhms *);
    217 static int dsrtc_clock_write_ymdhms(struct dsrtc_softc *, struct clock_ymdhms *);
    218 
    219 static int dsrtc_gettime_timeval(struct todr_chip_handle *, struct timeval *);
    220 static int dsrtc_settime_timeval(struct todr_chip_handle *, struct timeval *);
    221 static int dsrtc_clock_read_timeval(struct dsrtc_softc *, time_t *);
    222 static int dsrtc_clock_write_timeval(struct dsrtc_softc *, time_t);
    223 
    224 static int dsrtc_read_temp(struct dsrtc_softc *, uint32_t *);
    225 static void dsrtc_refresh(struct sysmon_envsys *, envsys_data_t *);
    226 
    227 static const struct dsrtc_model *
    228 dsrtc_model_by_number(u_int model)
    229 {
    230 	const struct device_compatible_entry *dce;
    231 	const struct dsrtc_model *dm;
    232 
    233 	/* no model given, assume it's a DS1307 */
    234 	if (model == 0)
    235 		return &ds1307_model;
    236 
    237 	for (dce = dsrtc_compat_data;
    238 	     DEVICE_COMPAT_ENTRY_IS_TERMINATOR(dce) == false; dce++) {
    239 		dm = DEVICE_COMPAT_ENTRY_GET_PTR(dce);
    240 		if (dm->dm_model == model)
    241 			return dm;
    242 	}
    243 	return NULL;
    244 }
    245 
    246 static const struct dsrtc_model *
    247 dsrtc_model_by_compat(const struct i2c_attach_args *ia)
    248 {
    249 	const struct dsrtc_model *dm = NULL;
    250 	const struct device_compatible_entry *dce;
    251 
    252 	dce = iic_compatible_match(ia, dsrtc_compat_data, NULL);
    253 	if (dce != NULL)
    254 		dm = DEVICE_COMPAT_ENTRY_GET_PTR(dce);
    255 
    256 	return dm;
    257 }
    258 
    259 static bool
    260 dsrtc_is_valid_addr_for_model(const struct dsrtc_model *dm, i2c_addr_t addr)
    261 {
    262 
    263 	for (int i = 0; dm->dm_valid_addrs[i] != 0; i++) {
    264 		if (addr == dm->dm_valid_addrs[i])
    265 			return true;
    266 	}
    267 	return false;
    268 }
    269 
    270 static int
    271 dsrtc_match(device_t parent, cfdata_t cf, void *arg)
    272 {
    273 	struct i2c_attach_args *ia = arg;
    274 	const struct dsrtc_model *dm;
    275 	int match_result;
    276 
    277 	if (iic_use_direct_match(ia, cf, dsrtc_compat_data, &match_result))
    278 		return match_result;
    279 
    280 	dm = dsrtc_model_by_number(cf->cf_flags & 0xffff);
    281 	if (dm == NULL)
    282 		return 0;
    283 
    284 	if (dsrtc_is_valid_addr_for_model(dm, ia->ia_addr))
    285 		return I2C_MATCH_ADDRESS_ONLY;
    286 
    287 	return 0;
    288 }
    289 
    290 static void
    291 dsrtc_attach(device_t parent, device_t self, void *arg)
    292 {
    293 	struct dsrtc_softc *sc = device_private(self);
    294 	struct i2c_attach_args *ia = arg;
    295 	const struct dsrtc_model *dm;
    296 
    297 	if ((dm = dsrtc_model_by_compat(ia)) == NULL)
    298 		dm = dsrtc_model_by_number(device_cfdata(self)->cf_flags);
    299 
    300 	if (dm == NULL) {
    301 		aprint_error(": unable to determine model!\n");
    302 		return;
    303 	}
    304 
    305 	aprint_naive(": Real-time Clock%s\n",
    306 	    dm->dm_nvram_size > 0 ? "/NVRAM" : "");
    307 	aprint_normal(": DS%u Real-time Clock%s\n", dm->dm_model,
    308 	    dm->dm_nvram_size > 0 ? "/NVRAM" : "");
    309 
    310 	sc->sc_tag = ia->ia_tag;
    311 	sc->sc_address = ia->ia_addr;
    312 	sc->sc_model = *dm;
    313 	sc->sc_dev = self;
    314 	sc->sc_open = 0;
    315 	sc->sc_todr.cookie = sc;
    316 	if (dm->dm_flags & DSRTC_FLAG_BCD) {
    317 		sc->sc_todr.todr_gettime_ymdhms = dsrtc_gettime_ymdhms;
    318 		sc->sc_todr.todr_settime_ymdhms = dsrtc_settime_ymdhms;
    319 	} else {
    320 		sc->sc_todr.todr_gettime = dsrtc_gettime_timeval;
    321 		sc->sc_todr.todr_settime = dsrtc_settime_timeval;
    322 	}
    323 	sc->sc_todr.todr_setwen = NULL;
    324 
    325 	todr_attach(&sc->sc_todr);
    326 	if ((sc->sc_model.dm_flags & DSRTC_FLAG_TEMP) != 0) {
    327 		int error;
    328 
    329 		sc->sc_sme = sysmon_envsys_create();
    330 		sc->sc_sme->sme_name = device_xname(self);
    331 		sc->sc_sme->sme_cookie = sc;
    332 		sc->sc_sme->sme_refresh = dsrtc_refresh;
    333 
    334 		sc->sc_sensor.units =  ENVSYS_STEMP;
    335 		sc->sc_sensor.state = ENVSYS_SINVALID;
    336 		sc->sc_sensor.flags = 0;
    337 		(void)strlcpy(sc->sc_sensor.desc, "temperature",
    338 		    sizeof(sc->sc_sensor.desc));
    339 
    340 		if (sysmon_envsys_sensor_attach(sc->sc_sme, &sc->sc_sensor)) {
    341 			aprint_error_dev(self, "unable to attach sensor\n");
    342 			goto bad;
    343 		}
    344 
    345 		error = sysmon_envsys_register(sc->sc_sme);
    346 		if (error) {
    347 			aprint_error_dev(self,
    348 			    "error %d registering with sysmon\n", error);
    349 			goto bad;
    350 		}
    351 	}
    352 	return;
    353 bad:
    354 	sysmon_envsys_destroy(sc->sc_sme);
    355 }
    356 
    357 /*ARGSUSED*/
    358 int
    359 dsrtc_open(dev_t dev, int flag, int fmt, struct lwp *l)
    360 {
    361 	struct dsrtc_softc *sc;
    362 
    363 	if ((sc = device_lookup_private(&dsrtc_cd, minor(dev))) == NULL)
    364 		return ENXIO;
    365 
    366 	/* XXX: Locking */
    367 	if (sc->sc_open)
    368 		return EBUSY;
    369 
    370 	sc->sc_open = true;
    371 	return 0;
    372 }
    373 
    374 /*ARGSUSED*/
    375 int
    376 dsrtc_close(dev_t dev, int flag, int fmt, struct lwp *l)
    377 {
    378 	struct dsrtc_softc *sc;
    379 
    380 	if ((sc = device_lookup_private(&dsrtc_cd, minor(dev))) == NULL)
    381 		return ENXIO;
    382 
    383 	sc->sc_open = false;
    384 	return 0;
    385 }
    386 
    387 /*ARGSUSED*/
    388 int
    389 dsrtc_read(dev_t dev, struct uio *uio, int flags)
    390 {
    391 	struct dsrtc_softc *sc;
    392 	int error;
    393 
    394 	if ((sc = device_lookup_private(&dsrtc_cd, minor(dev))) == NULL)
    395 		return ENXIO;
    396 
    397 	const struct dsrtc_model * const dm = &sc->sc_model;
    398 	if (uio->uio_offset >= dm->dm_nvram_size)
    399 		return EINVAL;
    400 
    401 	if ((error = iic_acquire_bus(sc->sc_tag, 0)) != 0)
    402 		return error;
    403 
    404 	KASSERT(uio->uio_offset >= 0);
    405 	while (uio->uio_resid && uio->uio_offset < dm->dm_nvram_size) {
    406 		uint8_t ch, cmd;
    407 		const u_int a = uio->uio_offset;
    408 		cmd = a + dm->dm_nvram_start;
    409 		if ((error = iic_exec(sc->sc_tag,
    410 		    uio->uio_resid > 1 ? I2C_OP_READ : I2C_OP_READ_WITH_STOP,
    411 		    sc->sc_address, &cmd, 1, &ch, 1, 0)) != 0) {
    412 			iic_release_bus(sc->sc_tag, 0);
    413 			aprint_error_dev(sc->sc_dev,
    414 			    "%s: read failed at 0x%x: %d\n",
    415 			    __func__, a, error);
    416 			return error;
    417 		}
    418 		if ((error = uiomove(&ch, 1, uio)) != 0) {
    419 			iic_release_bus(sc->sc_tag, 0);
    420 			return error;
    421 		}
    422 	}
    423 
    424 	iic_release_bus(sc->sc_tag, 0);
    425 
    426 	return 0;
    427 }
    428 
    429 /*ARGSUSED*/
    430 int
    431 dsrtc_write(dev_t dev, struct uio *uio, int flags)
    432 {
    433 	struct dsrtc_softc *sc;
    434 	int error;
    435 
    436 	if ((sc = device_lookup_private(&dsrtc_cd, minor(dev))) == NULL)
    437 		return ENXIO;
    438 
    439 	const struct dsrtc_model * const dm = &sc->sc_model;
    440 	if (uio->uio_offset >= dm->dm_nvram_size)
    441 		return EINVAL;
    442 
    443 	if ((error = iic_acquire_bus(sc->sc_tag, 0)) != 0)
    444 		return error;
    445 
    446 	while (uio->uio_resid && uio->uio_offset < dm->dm_nvram_size) {
    447 		uint8_t cmdbuf[2];
    448 		const u_int a = (int)uio->uio_offset;
    449 		cmdbuf[0] = a + dm->dm_nvram_start;
    450 		if ((error = uiomove(&cmdbuf[1], 1, uio)) != 0)
    451 			break;
    452 
    453 		if ((error = iic_exec(sc->sc_tag,
    454 		    uio->uio_resid ? I2C_OP_WRITE : I2C_OP_WRITE_WITH_STOP,
    455 		    sc->sc_address, cmdbuf, 1, &cmdbuf[1], 1, 0)) != 0) {
    456 			aprint_error_dev(sc->sc_dev,
    457 			    "%s: write failed at 0x%x: %d\n",
    458 			    __func__, a, error);
    459 			break;
    460 		}
    461 	}
    462 
    463 	iic_release_bus(sc->sc_tag, 0);
    464 
    465 	return error;
    466 }
    467 
    468 static int
    469 dsrtc_gettime_ymdhms(struct todr_chip_handle *ch, struct clock_ymdhms *dt)
    470 {
    471 	struct dsrtc_softc *sc = ch->cookie;
    472 	struct clock_ymdhms check;
    473 	int retries;
    474 
    475 	memset(dt, 0, sizeof(*dt));
    476 	memset(&check, 0, sizeof(check));
    477 
    478 	/*
    479 	 * Since we don't support Burst Read, we have to read the clock twice
    480 	 * until we get two consecutive identical results.
    481 	 */
    482 	retries = 5;
    483 	do {
    484 		dsrtc_clock_read_ymdhms(sc, dt);
    485 		dsrtc_clock_read_ymdhms(sc, &check);
    486 	} while (memcmp(dt, &check, sizeof(check)) != 0 && --retries);
    487 
    488 	return 0;
    489 }
    490 
    491 static int
    492 dsrtc_settime_ymdhms(struct todr_chip_handle *ch, struct clock_ymdhms *dt)
    493 {
    494 	struct dsrtc_softc *sc = ch->cookie;
    495 
    496 	if (dsrtc_clock_write_ymdhms(sc, dt) == 0)
    497 		return -1;
    498 
    499 	return 0;
    500 }
    501 
    502 static int
    503 dsrtc_clock_read_ymdhms(struct dsrtc_softc *sc, struct clock_ymdhms *dt)
    504 {
    505 	struct dsrtc_model * const dm = &sc->sc_model;
    506 	uint8_t bcd[DSXXXX_RTC_SIZE], cmdbuf[1];
    507 	int error;
    508 
    509 	KASSERT(DSXXXX_RTC_SIZE >= dm->dm_rtc_size);
    510 
    511 	if ((error = iic_acquire_bus(sc->sc_tag, I2C_F_POLL)) != 0) {
    512 		aprint_error_dev(sc->sc_dev,
    513 		    "%s: failed to acquire I2C bus: %d\n",
    514 		    __func__, error);
    515 		return 0;
    516 	}
    517 
    518 	/* Read each RTC register in order. */
    519 	for (u_int i = 0; !error && i < dm->dm_rtc_size; i++) {
    520 		cmdbuf[0] = dm->dm_rtc_start + i;
    521 
    522 		error = iic_exec(sc->sc_tag, I2C_OP_READ_WITH_STOP,
    523 		    sc->sc_address, cmdbuf, 1, &bcd[i], 1, I2C_F_POLL);
    524 	}
    525 
    526 	/* Done with I2C */
    527 	iic_release_bus(sc->sc_tag, I2C_F_POLL);
    528 
    529 	if (error != 0) {
    530 		aprint_error_dev(sc->sc_dev,
    531 		    "%s: failed to read rtc at 0x%x: %d\n",
    532 		    __func__, cmdbuf[0], error);
    533 		return 0;
    534 	}
    535 
    536 	/*
    537 	 * Convert the RTC's register values into something useable
    538 	 */
    539 	dt->dt_sec = bcdtobin(bcd[DSXXXX_SECONDS] & DSXXXX_SECONDS_MASK);
    540 	dt->dt_min = bcdtobin(bcd[DSXXXX_MINUTES] & DSXXXX_MINUTES_MASK);
    541 
    542 	if ((bcd[DSXXXX_HOURS] & DSXXXX_HOURS_12HRS_MODE) != 0) {
    543 		dt->dt_hour = bcdtobin(bcd[DSXXXX_HOURS] &
    544 		    DSXXXX_HOURS_12MASK) % 12; /* 12AM -> 0, 12PM -> 12 */
    545 		if (bcd[DSXXXX_HOURS] & DSXXXX_HOURS_12HRS_PM)
    546 			dt->dt_hour += 12;
    547 	} else
    548 		dt->dt_hour = bcdtobin(bcd[DSXXXX_HOURS] &
    549 		    DSXXXX_HOURS_24MASK);
    550 
    551 	dt->dt_day = bcdtobin(bcd[DSXXXX_DATE] & DSXXXX_DATE_MASK);
    552 	dt->dt_mon = bcdtobin(bcd[DSXXXX_MONTH] & DSXXXX_MONTH_MASK);
    553 
    554 	/* XXX: Should be an MD way to specify EPOCH used by BIOS/Firmware */
    555 	if (sc->sc_model.dm_flags & DSRTC_FLAG_YEAR_START_2K)
    556 		dt->dt_year = bcdtobin(bcd[DSXXXX_YEAR]) + 2000;
    557 	else {
    558 		dt->dt_year = bcdtobin(bcd[DSXXXX_YEAR]) + POSIX_BASE_YEAR;
    559 		if (bcd[DSXXXX_MONTH] & DSXXXX_MONTH_CENTURY)
    560 			dt->dt_year += 100;
    561 	}
    562 
    563 	return 1;
    564 }
    565 
    566 static int
    567 dsrtc_clock_write_ymdhms(struct dsrtc_softc *sc, struct clock_ymdhms *dt)
    568 {
    569 	struct dsrtc_model * const dm = &sc->sc_model;
    570 	uint8_t bcd[DSXXXX_RTC_SIZE], cmdbuf[2];
    571 	int error;
    572 
    573 	KASSERT(DSXXXX_RTC_SIZE >= dm->dm_rtc_size);
    574 
    575 	/*
    576 	 * Convert our time representation into something the DSXXXX
    577 	 * can understand.
    578 	 */
    579 	bcd[DSXXXX_SECONDS] = bintobcd(dt->dt_sec);
    580 	bcd[DSXXXX_MINUTES] = bintobcd(dt->dt_min);
    581 	bcd[DSXXXX_HOURS] = bintobcd(dt->dt_hour); /* DSXXXX_HOURS_12HRS_MODE=0 */
    582 	bcd[DSXXXX_DATE] = bintobcd(dt->dt_day);
    583 	bcd[DSXXXX_DAY] = bintobcd(dt->dt_wday);
    584 	bcd[DSXXXX_MONTH] = bintobcd(dt->dt_mon);
    585 	bcd[DSXXXX_YEAR] = bintobcd((dt->dt_year - POSIX_BASE_YEAR) % 100);
    586 	if (dt->dt_year - POSIX_BASE_YEAR >= 100)
    587 		bcd[DSXXXX_MONTH] |= DSXXXX_MONTH_CENTURY;
    588 
    589 	if ((error = iic_acquire_bus(sc->sc_tag, I2C_F_POLL)) != 0) {
    590 		aprint_error_dev(sc->sc_dev,
    591 		    "%s: failed to acquire I2C bus: %d\n",
    592 		    __func__, error);
    593 		return 0;
    594 	}
    595 
    596 	/* Stop the clock */
    597 	cmdbuf[0] = dm->dm_ch_reg;
    598 
    599 	if ((error = iic_exec(sc->sc_tag, I2C_OP_READ, sc->sc_address,
    600 	    cmdbuf, 1, &cmdbuf[1], 1, I2C_F_POLL)) != 0) {
    601 		iic_release_bus(sc->sc_tag, I2C_F_POLL);
    602 		aprint_error_dev(sc->sc_dev,
    603 		    "%s: failed to read Hold Clock: %d\n",
    604 		    __func__, error);
    605 		return 0;
    606 	}
    607 
    608 	if (sc->sc_model.dm_flags & DSRTC_FLAG_CLOCK_HOLD_REVERSED)
    609 		cmdbuf[1] &= ~dm->dm_ch_value;
    610 	else
    611 		cmdbuf[1] |= dm->dm_ch_value;
    612 
    613 	if ((error = iic_exec(sc->sc_tag, I2C_OP_WRITE, sc->sc_address,
    614 	    cmdbuf, 1, &cmdbuf[1], 1, I2C_F_POLL)) != 0) {
    615 		iic_release_bus(sc->sc_tag, I2C_F_POLL);
    616 		aprint_error_dev(sc->sc_dev,
    617 		    "%s: failed to write Hold Clock: %d\n",
    618 		    __func__, error);
    619 		return 0;
    620 	}
    621 
    622 	/*
    623 	 * Write registers in reverse order. The last write (to the Seconds
    624 	 * register) will undo the Clock Hold, above.
    625 	 */
    626 	uint8_t op = I2C_OP_WRITE;
    627 	for (signed int i = dm->dm_rtc_size - 1; i >= 0; i--) {
    628 		cmdbuf[0] = dm->dm_rtc_start + i;
    629 		if ((dm->dm_flags & DSRTC_FLAG_VBATEN) &&
    630 				dm->dm_rtc_start + i == dm->dm_vbaten_reg)
    631 			bcd[i] |= dm->dm_vbaten_value;
    632 		if (dm->dm_rtc_start + i == dm->dm_ch_reg) {
    633 			op = I2C_OP_WRITE_WITH_STOP;
    634 			if (dm->dm_flags & DSRTC_FLAG_CLOCK_HOLD_REVERSED)
    635 				bcd[i] |= dm->dm_ch_value;
    636 		}
    637 		if ((error = iic_exec(sc->sc_tag, op, sc->sc_address,
    638 		    cmdbuf, 1, &bcd[i], 1, I2C_F_POLL)) != 0) {
    639 			iic_release_bus(sc->sc_tag, I2C_F_POLL);
    640 			aprint_error_dev(sc->sc_dev,
    641 			    "%s: failed to write rtc at 0x%x: %d\n",
    642 			    __func__, i, error);
    643 			/* XXX: Clock Hold is likely still asserted! */
    644 			return 0;
    645 		}
    646 	}
    647 	/*
    648 	 * If the clock hold register isn't the same register as seconds,
    649 	 * we need to reeanble the clock.
    650 	 */
    651 	if (op != I2C_OP_WRITE_WITH_STOP) {
    652 		cmdbuf[0] = dm->dm_ch_reg;
    653 		if (dm->dm_flags & DSRTC_FLAG_CLOCK_HOLD_REVERSED)
    654 			cmdbuf[1] |= dm->dm_ch_value;
    655 		else
    656 			cmdbuf[1] &= ~dm->dm_ch_value;
    657 
    658 		if ((error = iic_exec(sc->sc_tag, I2C_OP_WRITE_WITH_STOP,
    659 		    sc->sc_address, cmdbuf, 1, &cmdbuf[1], 1,
    660 		    I2C_F_POLL)) != 0) {
    661 			iic_release_bus(sc->sc_tag, I2C_F_POLL);
    662 			aprint_error_dev(sc->sc_dev,
    663 			    "%s: failed to Hold Clock: %d\n",
    664 			    __func__, error);
    665 			return 0;
    666 		}
    667 	}
    668 
    669 	iic_release_bus(sc->sc_tag, I2C_F_POLL);
    670 
    671 	return 1;
    672 }
    673 
    674 static int
    675 dsrtc_gettime_timeval(struct todr_chip_handle *ch, struct timeval *tv)
    676 {
    677 	struct dsrtc_softc *sc = ch->cookie;
    678 	struct timeval check;
    679 	int retries;
    680 
    681 	memset(tv, 0, sizeof(*tv));
    682 	memset(&check, 0, sizeof(check));
    683 
    684 	/*
    685 	 * Since we don't support Burst Read, we have to read the clock twice
    686 	 * until we get two consecutive identical results.
    687 	 */
    688 	retries = 5;
    689 	do {
    690 		dsrtc_clock_read_timeval(sc, &tv->tv_sec);
    691 		dsrtc_clock_read_timeval(sc, &check.tv_sec);
    692 	} while (memcmp(tv, &check, sizeof(check)) != 0 && --retries);
    693 
    694 	return 0;
    695 }
    696 
    697 static int
    698 dsrtc_settime_timeval(struct todr_chip_handle *ch, struct timeval *tv)
    699 {
    700 	struct dsrtc_softc *sc = ch->cookie;
    701 
    702 	if (dsrtc_clock_write_timeval(sc, tv->tv_sec) == 0)
    703 		return -1;
    704 
    705 	return 0;
    706 }
    707 
    708 /*
    709  * The RTC probably has a nice Clock Burst Read/Write command, but we can't use
    710  * it, since some I2C controllers don't support anything other than single-byte
    711  * transfers.
    712  */
    713 static int
    714 dsrtc_clock_read_timeval(struct dsrtc_softc *sc, time_t *tp)
    715 {
    716 	const struct dsrtc_model * const dm = &sc->sc_model;
    717 	uint8_t buf[4];
    718 	int error;
    719 
    720 	if ((error = iic_acquire_bus(sc->sc_tag, I2C_F_POLL)) != 0) {
    721 		aprint_error_dev(sc->sc_dev,
    722 		    "%s: failed to acquire I2C bus: %d\n",
    723 		    __func__, error);
    724 		return 0;
    725 	}
    726 
    727 	/* read all registers: */
    728 	uint8_t reg = dm->dm_rtc_start;
    729 	error = iic_exec(sc->sc_tag, I2C_OP_READ_WITH_STOP, sc->sc_address,
    730 	     &reg, 1, buf, 4, I2C_F_POLL);
    731 
    732 	/* Done with I2C */
    733 	iic_release_bus(sc->sc_tag, I2C_F_POLL);
    734 
    735 	if (error != 0) {
    736 		aprint_error_dev(sc->sc_dev,
    737 		    "%s: failed to read rtc at 0x%x: %d\n",
    738 		    __func__, reg, error);
    739 		return 0;
    740 	}
    741 
    742 	uint32_t v = (buf[3] << 24) | (buf[2] << 16) | (buf[1] << 8) | buf[0];
    743 	*tp = v;
    744 
    745 	aprint_debug_dev(sc->sc_dev, "%s: cntr=0x%08"PRIx32"\n",
    746 	    __func__, v);
    747 
    748 	return 1;
    749 }
    750 
    751 static int
    752 dsrtc_clock_write_timeval(struct dsrtc_softc *sc, time_t t)
    753 {
    754 	const struct dsrtc_model * const dm = &sc->sc_model;
    755 	size_t buflen = dm->dm_rtc_size + 2;
    756 	uint8_t buf[buflen];
    757 	int error;
    758 
    759 	KASSERT((dm->dm_flags & DSRTC_FLAG_CLOCK_HOLD) == 0);
    760 	KASSERT(dm->dm_ch_reg == dm->dm_rtc_start + 4);
    761 
    762 	buf[0] = dm->dm_rtc_start;
    763 	buf[1] = (t >> 0) & 0xff;
    764 	buf[2] = (t >> 8) & 0xff;
    765 	buf[3] = (t >> 16) & 0xff;
    766 	buf[4] = (t >> 24) & 0xff;
    767 	buf[5] = 0;
    768 
    769 	if ((error = iic_acquire_bus(sc->sc_tag, I2C_F_POLL)) != 0) {
    770 		aprint_error_dev(sc->sc_dev,
    771 		    "%s: failed to acquire I2C bus: %d\n",
    772 		    __func__, error);
    773 		return 0;
    774 	}
    775 
    776 	error = iic_exec(sc->sc_tag, I2C_OP_WRITE_WITH_STOP, sc->sc_address,
    777 	    &buf, buflen, NULL, 0, I2C_F_POLL);
    778 
    779 	/* Done with I2C */
    780 	iic_release_bus(sc->sc_tag, I2C_F_POLL);
    781 
    782 	/* send data */
    783 	if (error != 0) {
    784 		aprint_error_dev(sc->sc_dev,
    785 		    "%s: failed to set time: %d\n",
    786 		    __func__, error);
    787 		return 0;
    788 	}
    789 
    790 	return 1;
    791 }
    792 
    793 static int
    794 dsrtc_read_temp(struct dsrtc_softc *sc, uint32_t *temp)
    795 {
    796 	int error, tc;
    797 	uint8_t reg = DS3232_TEMP_MSB;
    798 	uint8_t buf[2];
    799 
    800 	if ((sc->sc_model.dm_flags & DSRTC_FLAG_TEMP) == 0)
    801 		return ENOTSUP;
    802 
    803 	if ((error = iic_acquire_bus(sc->sc_tag, I2C_F_POLL)) != 0) {
    804 		aprint_error_dev(sc->sc_dev,
    805 		    "%s: failed to acquire I2C bus: %d\n",
    806 		    __func__, error);
    807 		return 0;
    808 	}
    809 
    810 	/* read temperature registers: */
    811 	error = iic_exec(sc->sc_tag, I2C_OP_READ_WITH_STOP, sc->sc_address,
    812 	     &reg, 1, buf, 2, I2C_F_POLL);
    813 
    814 	/* Done with I2C */
    815 	iic_release_bus(sc->sc_tag, I2C_F_POLL);
    816 
    817 	if (error != 0) {
    818 		aprint_error_dev(sc->sc_dev,
    819 		    "%s: failed to read temperature: %d\n",
    820 		    __func__, error);
    821 		return 0;
    822 	}
    823 
    824 	/* convert to microkelvin */
    825 	tc = buf[0] * 1000000 + (buf[1] >> 6) * 250000;
    826 	*temp = tc + 273150000;
    827 	return 1;
    828 }
    829 
    830 static void
    831 dsrtc_refresh(struct sysmon_envsys *sme, envsys_data_t *edata)
    832 {
    833 	struct dsrtc_softc *sc = sme->sme_cookie;
    834 	uint32_t temp = 0;	/* XXX gcc */
    835 
    836 	if (dsrtc_read_temp(sc, &temp) == 0) {
    837 		edata->state = ENVSYS_SINVALID;
    838 		return;
    839 	}
    840 
    841 	edata->value_cur = temp;
    842 
    843 	edata->state = ENVSYS_SVALID;
    844 }
    845