xref: /netbsd-src/sys/dev/i2c/ds1307.c (revision f21b7d7f2cbdd5c14b3882c4e8a3d43580d460a6)
1 /*	$NetBSD: ds1307.c,v 1.23 2016/10/04 15:06:59 kiyohara 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 1.23 2016/10/04 15:06:59 kiyohara 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 struct dsrtc_model {
57 	uint16_t dm_model;
58 	uint8_t dm_ch_reg;
59 	uint8_t dm_ch_value;
60 	uint8_t dm_rtc_start;
61 	uint8_t dm_rtc_size;
62 	uint8_t dm_nvram_start;
63 	uint8_t dm_nvram_size;
64 	uint8_t dm_flags;
65 #define	DSRTC_FLAG_CLOCK_HOLD	1
66 #define	DSRTC_FLAG_BCD		2
67 #define	DSRTC_FLAG_TEMP		4
68 };
69 
70 static const struct dsrtc_model dsrtc_models[] = {
71 	{
72 		.dm_model = 1307,
73 		.dm_ch_reg = DSXXXX_SECONDS,
74 		.dm_ch_value = DS1307_SECONDS_CH,
75 		.dm_rtc_start = DS1307_RTC_START,
76 		.dm_rtc_size = DS1307_RTC_SIZE,
77 		.dm_nvram_start = DS1307_NVRAM_START,
78 		.dm_nvram_size = DS1307_NVRAM_SIZE,
79 		.dm_flags = DSRTC_FLAG_BCD | DSRTC_FLAG_CLOCK_HOLD,
80 	}, {
81 		.dm_model = 1339,
82 		.dm_rtc_start = DS1339_RTC_START,
83 		.dm_rtc_size = DS1339_RTC_SIZE,
84 		.dm_flags = DSRTC_FLAG_BCD,
85 	}, {
86 		.dm_model = 1340,
87 		.dm_ch_reg = DSXXXX_SECONDS,
88 		.dm_ch_value = DS1340_SECONDS_EOSC,
89 		.dm_rtc_start = DS1340_RTC_START,
90 		.dm_rtc_size = DS1340_RTC_SIZE,
91 		.dm_flags = DSRTC_FLAG_BCD,
92 	}, {
93 		.dm_model = 1672,
94 		.dm_rtc_start = DS1672_RTC_START,
95 		.dm_rtc_size = DS1672_RTC_SIZE,
96 		.dm_ch_reg = DS1672_CONTROL,
97 		.dm_ch_value = DS1672_CONTROL_CH,
98 		.dm_flags = 0,
99 	}, {
100 		.dm_model = 3231,
101 		.dm_rtc_start = DS3232_RTC_START,
102 		.dm_rtc_size = DS3232_RTC_SIZE,
103 		/*
104 		 * XXX
105 		 * the DS3232 likely has the temperature sensor too but I can't
106 		 * easily verify or test that right now
107 		 */
108 		.dm_flags = DSRTC_FLAG_BCD | DSRTC_FLAG_TEMP,
109 	}, {
110 		.dm_model = 3232,
111 		.dm_rtc_start = DS3232_RTC_START,
112 		.dm_rtc_size = DS3232_RTC_SIZE,
113 		.dm_nvram_start = DS3232_NVRAM_START,
114 		.dm_nvram_size = DS3232_NVRAM_SIZE,
115 		.dm_flags = DSRTC_FLAG_BCD,
116 	},
117 };
118 
119 struct dsrtc_softc {
120 	device_t sc_dev;
121 	i2c_tag_t sc_tag;
122 	uint8_t sc_address;
123 	bool sc_open;
124 	struct dsrtc_model sc_model;
125 	struct todr_chip_handle sc_todr;
126 	struct sysmon_envsys *sc_sme;
127 	envsys_data_t sc_sensor;
128 };
129 
130 static void	dsrtc_attach(device_t, device_t, void *);
131 static int	dsrtc_match(device_t, cfdata_t, void *);
132 
133 CFATTACH_DECL_NEW(dsrtc, sizeof(struct dsrtc_softc),
134     dsrtc_match, dsrtc_attach, NULL, NULL);
135 extern struct cfdriver dsrtc_cd;
136 
137 dev_type_open(dsrtc_open);
138 dev_type_close(dsrtc_close);
139 dev_type_read(dsrtc_read);
140 dev_type_write(dsrtc_write);
141 
142 const struct cdevsw dsrtc_cdevsw = {
143 	.d_open = dsrtc_open,
144 	.d_close = dsrtc_close,
145 	.d_read = dsrtc_read,
146 	.d_write = dsrtc_write,
147 	.d_ioctl = noioctl,
148 	.d_stop = nostop,
149 	.d_tty = notty,
150 	.d_poll = nopoll,
151 	.d_mmap = nommap,
152 	.d_kqfilter = nokqfilter,
153 	.d_discard = nodiscard,
154 	.d_flag = D_OTHER
155 };
156 
157 static int dsrtc_gettime_ymdhms(struct todr_chip_handle *, struct clock_ymdhms *);
158 static int dsrtc_settime_ymdhms(struct todr_chip_handle *, struct clock_ymdhms *);
159 static int dsrtc_clock_read_ymdhms(struct dsrtc_softc *, struct clock_ymdhms *);
160 static int dsrtc_clock_write_ymdhms(struct dsrtc_softc *, struct clock_ymdhms *);
161 
162 static int dsrtc_gettime_timeval(struct todr_chip_handle *, struct timeval *);
163 static int dsrtc_settime_timeval(struct todr_chip_handle *, struct timeval *);
164 static int dsrtc_clock_read_timeval(struct dsrtc_softc *, time_t *);
165 static int dsrtc_clock_write_timeval(struct dsrtc_softc *, time_t);
166 
167 static int dsrtc_read_temp(struct dsrtc_softc *, uint32_t *);
168 static void dsrtc_refresh(struct sysmon_envsys *, envsys_data_t *);
169 
170 static const struct dsrtc_model *
171 dsrtc_model(u_int model)
172 {
173 	/* no model given, assume it's a DS1307 (the first one) */
174 	if (model == 0)
175 		return &dsrtc_models[0];
176 
177 	for (const struct dsrtc_model *dm = dsrtc_models;
178 	     dm < dsrtc_models + __arraycount(dsrtc_models); dm++) {
179 		if (dm->dm_model == model)
180 			return dm;
181 	}
182 	return NULL;
183 }
184 
185 static int
186 dsrtc_match(device_t parent, cfdata_t cf, void *arg)
187 {
188 	struct i2c_attach_args *ia = arg;
189 
190 	if (ia->ia_name) {
191 		/* direct config - check name */
192 		if (strcmp(ia->ia_name, "dsrtc") == 0)
193 			return 1;
194 	} else {
195 		/* indirect config - check typical address */
196 		if (ia->ia_addr == DS1307_ADDR)
197 			return dsrtc_model(cf->cf_flags & 0xffff) != NULL;
198 	}
199 	return 0;
200 }
201 
202 static void
203 dsrtc_attach(device_t parent, device_t self, void *arg)
204 {
205 	struct dsrtc_softc *sc = device_private(self);
206 	struct i2c_attach_args *ia = arg;
207 	const struct dsrtc_model * const dm =
208 	    dsrtc_model(device_cfdata(self)->cf_flags);
209 
210 	aprint_naive(": Real-time Clock%s\n",
211 	    dm->dm_nvram_size > 0 ? "/NVRAM" : "");
212 	aprint_normal(": DS%u Real-time Clock%s\n", dm->dm_model,
213 	    dm->dm_nvram_size > 0 ? "/NVRAM" : "");
214 
215 	sc->sc_tag = ia->ia_tag;
216 	sc->sc_address = ia->ia_addr;
217 	sc->sc_model = *dm;
218 	sc->sc_dev = self;
219 	sc->sc_open = 0;
220 	sc->sc_todr.cookie = sc;
221 	if (dm->dm_flags & DSRTC_FLAG_BCD) {
222 		sc->sc_todr.todr_gettime_ymdhms = dsrtc_gettime_ymdhms;
223 		sc->sc_todr.todr_settime_ymdhms = dsrtc_settime_ymdhms;
224 	} else {
225 		sc->sc_todr.todr_gettime = dsrtc_gettime_timeval;
226 		sc->sc_todr.todr_settime = dsrtc_settime_timeval;
227 	}
228 	sc->sc_todr.todr_setwen = NULL;
229 
230 	todr_attach(&sc->sc_todr);
231 	if ((sc->sc_model.dm_flags & DSRTC_FLAG_TEMP) != 0) {
232 		int error;
233 
234 		sc->sc_sme = sysmon_envsys_create();
235 		sc->sc_sme->sme_name = device_xname(self);
236 		sc->sc_sme->sme_cookie = sc;
237 		sc->sc_sme->sme_refresh = dsrtc_refresh;
238 
239 		sc->sc_sensor.units =  ENVSYS_STEMP;
240 		sc->sc_sensor.state = ENVSYS_SINVALID;
241 		sc->sc_sensor.flags = 0;
242 		(void)strlcpy(sc->sc_sensor.desc, "temperature",
243 		    sizeof(sc->sc_sensor.desc));
244 
245 		if (sysmon_envsys_sensor_attach(sc->sc_sme, &sc->sc_sensor)) {
246 			aprint_error_dev(self, "unable to attach sensor\n");
247 			goto bad;
248 		}
249 
250 		error = sysmon_envsys_register(sc->sc_sme);
251 		if (error) {
252 			aprint_error_dev(self,
253 			    "error %d registering with sysmon\n", error);
254 			goto bad;
255 		}
256 	}
257 	return;
258 bad:
259 	sysmon_envsys_destroy(sc->sc_sme);
260 }
261 
262 /*ARGSUSED*/
263 int
264 dsrtc_open(dev_t dev, int flag, int fmt, struct lwp *l)
265 {
266 	struct dsrtc_softc *sc;
267 
268 	if ((sc = device_lookup_private(&dsrtc_cd, minor(dev))) == NULL)
269 		return ENXIO;
270 
271 	/* XXX: Locking */
272 	if (sc->sc_open)
273 		return EBUSY;
274 
275 	sc->sc_open = true;
276 	return 0;
277 }
278 
279 /*ARGSUSED*/
280 int
281 dsrtc_close(dev_t dev, int flag, int fmt, struct lwp *l)
282 {
283 	struct dsrtc_softc *sc;
284 
285 	if ((sc = device_lookup_private(&dsrtc_cd, minor(dev))) == NULL)
286 		return ENXIO;
287 
288 	sc->sc_open = false;
289 	return 0;
290 }
291 
292 /*ARGSUSED*/
293 int
294 dsrtc_read(dev_t dev, struct uio *uio, int flags)
295 {
296 	struct dsrtc_softc *sc;
297 	int error;
298 
299 	if ((sc = device_lookup_private(&dsrtc_cd, minor(dev))) == NULL)
300 		return ENXIO;
301 
302 	const struct dsrtc_model * const dm = &sc->sc_model;
303 	if (uio->uio_offset >= dm->dm_nvram_size)
304 		return EINVAL;
305 
306 	if ((error = iic_acquire_bus(sc->sc_tag, 0)) != 0)
307 		return error;
308 
309 	KASSERT(uio->uio_offset >= 0);
310 	while (uio->uio_resid && uio->uio_offset < dm->dm_nvram_size) {
311 		uint8_t ch, cmd;
312 		const u_int a = uio->uio_offset;
313 		cmd = a + dm->dm_nvram_start;
314 		if ((error = iic_exec(sc->sc_tag,
315 		    uio->uio_resid > 1 ? I2C_OP_READ : I2C_OP_READ_WITH_STOP,
316 		    sc->sc_address, &cmd, 1, &ch, 1, 0)) != 0) {
317 			iic_release_bus(sc->sc_tag, 0);
318 			aprint_error_dev(sc->sc_dev,
319 			    "%s: read failed at 0x%x: %d\n",
320 			    __func__, a, error);
321 			return error;
322 		}
323 		if ((error = uiomove(&ch, 1, uio)) != 0) {
324 			iic_release_bus(sc->sc_tag, 0);
325 			return error;
326 		}
327 	}
328 
329 	iic_release_bus(sc->sc_tag, 0);
330 
331 	return 0;
332 }
333 
334 /*ARGSUSED*/
335 int
336 dsrtc_write(dev_t dev, struct uio *uio, int flags)
337 {
338 	struct dsrtc_softc *sc;
339 	int error;
340 
341 	if ((sc = device_lookup_private(&dsrtc_cd, minor(dev))) == NULL)
342 		return ENXIO;
343 
344 	const struct dsrtc_model * const dm = &sc->sc_model;
345 	if (uio->uio_offset >= dm->dm_nvram_size)
346 		return EINVAL;
347 
348 	if ((error = iic_acquire_bus(sc->sc_tag, 0)) != 0)
349 		return error;
350 
351 	while (uio->uio_resid && uio->uio_offset < dm->dm_nvram_size) {
352 		uint8_t cmdbuf[2];
353 		const u_int a = (int)uio->uio_offset;
354 		cmdbuf[0] = a + dm->dm_nvram_start;
355 		if ((error = uiomove(&cmdbuf[1], 1, uio)) != 0)
356 			break;
357 
358 		if ((error = iic_exec(sc->sc_tag,
359 		    uio->uio_resid ? I2C_OP_WRITE : I2C_OP_WRITE_WITH_STOP,
360 		    sc->sc_address, cmdbuf, 1, &cmdbuf[1], 1, 0)) != 0) {
361 			aprint_error_dev(sc->sc_dev,
362 			    "%s: write failed at 0x%x: %d\n",
363 			    __func__, a, error);
364 			break;
365 		}
366 	}
367 
368 	iic_release_bus(sc->sc_tag, 0);
369 
370 	return error;
371 }
372 
373 static int
374 dsrtc_gettime_ymdhms(struct todr_chip_handle *ch, struct clock_ymdhms *dt)
375 {
376 	struct dsrtc_softc *sc = ch->cookie;
377 	struct clock_ymdhms check;
378 	int retries;
379 
380 	memset(dt, 0, sizeof(*dt));
381 	memset(&check, 0, sizeof(check));
382 
383 	/*
384 	 * Since we don't support Burst Read, we have to read the clock twice
385 	 * until we get two consecutive identical results.
386 	 */
387 	retries = 5;
388 	do {
389 		dsrtc_clock_read_ymdhms(sc, dt);
390 		dsrtc_clock_read_ymdhms(sc, &check);
391 	} while (memcmp(dt, &check, sizeof(check)) != 0 && --retries);
392 
393 	return 0;
394 }
395 
396 static int
397 dsrtc_settime_ymdhms(struct todr_chip_handle *ch, struct clock_ymdhms *dt)
398 {
399 	struct dsrtc_softc *sc = ch->cookie;
400 
401 	if (dsrtc_clock_write_ymdhms(sc, dt) == 0)
402 		return -1;
403 
404 	return 0;
405 }
406 
407 static int
408 dsrtc_clock_read_ymdhms(struct dsrtc_softc *sc, struct clock_ymdhms *dt)
409 {
410 	struct dsrtc_model * const dm = &sc->sc_model;
411 	uint8_t bcd[DSXXXX_RTC_SIZE], cmdbuf[1];
412 	int error;
413 
414 	KASSERT(DSXXXX_RTC_SIZE >= dm->dm_rtc_size);
415 
416 	if ((error = iic_acquire_bus(sc->sc_tag, I2C_F_POLL)) != 0) {
417 		aprint_error_dev(sc->sc_dev,
418 		    "%s: failed to acquire I2C bus: %d\n",
419 		    __func__, error);
420 		return 0;
421 	}
422 
423 	/* Read each RTC register in order. */
424 	for (u_int i = 0; !error && i < dm->dm_rtc_size; i++) {
425 		cmdbuf[0] = dm->dm_rtc_start + i;
426 
427 		error = iic_exec(sc->sc_tag, I2C_OP_READ_WITH_STOP,
428 		    sc->sc_address, cmdbuf, 1, &bcd[i], 1, I2C_F_POLL);
429 	}
430 
431 	/* Done with I2C */
432 	iic_release_bus(sc->sc_tag, I2C_F_POLL);
433 
434 	if (error != 0) {
435 		aprint_error_dev(sc->sc_dev,
436 		    "%s: failed to read rtc at 0x%x: %d\n",
437 		    __func__, cmdbuf[0], error);
438 		return 0;
439 	}
440 
441 	/*
442 	 * Convert the RTC's register values into something useable
443 	 */
444 	dt->dt_sec = bcdtobin(bcd[DSXXXX_SECONDS] & DSXXXX_SECONDS_MASK);
445 	dt->dt_min = bcdtobin(bcd[DSXXXX_MINUTES] & DSXXXX_MINUTES_MASK);
446 
447 	if ((bcd[DSXXXX_HOURS] & DSXXXX_HOURS_12HRS_MODE) != 0) {
448 		dt->dt_hour = bcdtobin(bcd[DSXXXX_HOURS] &
449 		    DSXXXX_HOURS_12MASK) % 12; /* 12AM -> 0, 12PM -> 12 */
450 		if (bcd[DSXXXX_HOURS] & DSXXXX_HOURS_12HRS_PM)
451 			dt->dt_hour += 12;
452 	} else
453 		dt->dt_hour = bcdtobin(bcd[DSXXXX_HOURS] &
454 		    DSXXXX_HOURS_24MASK);
455 
456 	dt->dt_day = bcdtobin(bcd[DSXXXX_DATE] & DSXXXX_DATE_MASK);
457 	dt->dt_mon = bcdtobin(bcd[DSXXXX_MONTH] & DSXXXX_MONTH_MASK);
458 
459 	/* XXX: Should be an MD way to specify EPOCH used by BIOS/Firmware */
460 	dt->dt_year = bcdtobin(bcd[DSXXXX_YEAR]) + POSIX_BASE_YEAR;
461 	if (bcd[DSXXXX_MONTH] & DSXXXX_MONTH_CENTURY)
462 		dt->dt_year += 100;
463 
464 	return 1;
465 }
466 
467 static int
468 dsrtc_clock_write_ymdhms(struct dsrtc_softc *sc, struct clock_ymdhms *dt)
469 {
470 	struct dsrtc_model * const dm = &sc->sc_model;
471 	uint8_t bcd[DSXXXX_RTC_SIZE], cmdbuf[2];
472 	int error;
473 
474 	KASSERT(DSXXXX_RTC_SIZE >= dm->dm_rtc_size);
475 
476 	/*
477 	 * Convert our time representation into something the DSXXXX
478 	 * can understand.
479 	 */
480 	bcd[DSXXXX_SECONDS] = bintobcd(dt->dt_sec);
481 	bcd[DSXXXX_MINUTES] = bintobcd(dt->dt_min);
482 	bcd[DSXXXX_HOURS] = bintobcd(dt->dt_hour); /* DSXXXX_HOURS_12HRS_MODE=0 */
483 	bcd[DSXXXX_DATE] = bintobcd(dt->dt_day);
484 	bcd[DSXXXX_DAY] = bintobcd(dt->dt_wday);
485 	bcd[DSXXXX_MONTH] = bintobcd(dt->dt_mon);
486 	bcd[DSXXXX_YEAR] = bintobcd((dt->dt_year - POSIX_BASE_YEAR) % 100);
487 	if (dt->dt_year - POSIX_BASE_YEAR >= 100)
488 		bcd[DSXXXX_MONTH] |= DSXXXX_MONTH_CENTURY;
489 
490 	if ((error = iic_acquire_bus(sc->sc_tag, I2C_F_POLL)) != 0) {
491 		aprint_error_dev(sc->sc_dev,
492 		    "%s: failed to acquire I2C bus: %d\n",
493 		    __func__, error);
494 		return 0;
495 	}
496 
497 	/* Stop the clock */
498 	cmdbuf[0] = dm->dm_ch_reg;
499 
500 	if ((error = iic_exec(sc->sc_tag, I2C_OP_READ, sc->sc_address,
501 	    cmdbuf, 1, &cmdbuf[1], 1, I2C_F_POLL)) != 0) {
502 		iic_release_bus(sc->sc_tag, I2C_F_POLL);
503 		aprint_error_dev(sc->sc_dev,
504 		    "%s: failed to read Hold Clock: %d\n",
505 		    __func__, error);
506 		return 0;
507 	}
508 
509 	cmdbuf[1] |= dm->dm_ch_value;
510 
511 	if ((error = iic_exec(sc->sc_tag, I2C_OP_WRITE, sc->sc_address,
512 	    cmdbuf, 1, &cmdbuf[1], 1, I2C_F_POLL)) != 0) {
513 		iic_release_bus(sc->sc_tag, I2C_F_POLL);
514 		aprint_error_dev(sc->sc_dev,
515 		    "%s: failed to write Hold Clock: %d\n",
516 		    __func__, error);
517 		return 0;
518 	}
519 
520 	/*
521 	 * Write registers in reverse order. The last write (to the Seconds
522 	 * register) will undo the Clock Hold, above.
523 	 */
524 	uint8_t op = I2C_OP_WRITE;
525 	for (signed int i = dm->dm_rtc_size - 1; i >= 0; i--) {
526 		cmdbuf[0] = dm->dm_rtc_start + i;
527 		if (dm->dm_rtc_start + i == dm->dm_ch_reg) {
528 			op = I2C_OP_WRITE_WITH_STOP;
529 		}
530 		if ((error = iic_exec(sc->sc_tag, op, sc->sc_address,
531 		    cmdbuf, 1, &bcd[i], 1, I2C_F_POLL)) != 0) {
532 			iic_release_bus(sc->sc_tag, I2C_F_POLL);
533 			aprint_error_dev(sc->sc_dev,
534 			    "%s: failed to write rtc at 0x%x: %d\n",
535 			    __func__, i, error);
536 			/* XXX: Clock Hold is likely still asserted! */
537 			return 0;
538 		}
539 	}
540 	/*
541 	 * If the clock hold register isn't the same register as seconds,
542 	 * we need to reeanble the clock.
543 	 */
544 	if (op != I2C_OP_WRITE_WITH_STOP) {
545 		cmdbuf[0] = dm->dm_ch_reg;
546 		cmdbuf[1] &= ~dm->dm_ch_value;
547 
548 		if ((error = iic_exec(sc->sc_tag, I2C_OP_WRITE_WITH_STOP,
549 		    sc->sc_address, cmdbuf, 1, &cmdbuf[1], 1,
550 		    I2C_F_POLL)) != 0) {
551 			iic_release_bus(sc->sc_tag, I2C_F_POLL);
552 			aprint_error_dev(sc->sc_dev,
553 			    "%s: failed to Hold Clock: %d\n",
554 			    __func__, error);
555 			return 0;
556 		}
557 	}
558 
559 	iic_release_bus(sc->sc_tag, I2C_F_POLL);
560 
561 	return 1;
562 }
563 
564 static int
565 dsrtc_gettime_timeval(struct todr_chip_handle *ch, struct timeval *tv)
566 {
567 	struct dsrtc_softc *sc = ch->cookie;
568 	struct timeval check;
569 	int retries;
570 
571 	memset(tv, 0, sizeof(*tv));
572 	memset(&check, 0, sizeof(check));
573 
574 	/*
575 	 * Since we don't support Burst Read, we have to read the clock twice
576 	 * until we get two consecutive identical results.
577 	 */
578 	retries = 5;
579 	do {
580 		dsrtc_clock_read_timeval(sc, &tv->tv_sec);
581 		dsrtc_clock_read_timeval(sc, &check.tv_sec);
582 	} while (memcmp(tv, &check, sizeof(check)) != 0 && --retries);
583 
584 	return 0;
585 }
586 
587 static int
588 dsrtc_settime_timeval(struct todr_chip_handle *ch, struct timeval *tv)
589 {
590 	struct dsrtc_softc *sc = ch->cookie;
591 
592 	if (dsrtc_clock_write_timeval(sc, tv->tv_sec) == 0)
593 		return -1;
594 
595 	return 0;
596 }
597 
598 /*
599  * The RTC probably has a nice Clock Burst Read/Write command, but we can't use
600  * it, since some I2C controllers don't support anything other than single-byte
601  * transfers.
602  */
603 static int
604 dsrtc_clock_read_timeval(struct dsrtc_softc *sc, time_t *tp)
605 {
606 	const struct dsrtc_model * const dm = &sc->sc_model;
607 	uint8_t buf[4];
608 	int error;
609 
610 	if ((error = iic_acquire_bus(sc->sc_tag, I2C_F_POLL)) != 0) {
611 		aprint_error_dev(sc->sc_dev,
612 		    "%s: failed to acquire I2C bus: %d\n",
613 		    __func__, error);
614 		return 0;
615 	}
616 
617 	/* read all registers: */
618 	uint8_t reg = dm->dm_rtc_start;
619 	error = iic_exec(sc->sc_tag, I2C_OP_READ_WITH_STOP, sc->sc_address,
620 	     &reg, 1, buf, 4, I2C_F_POLL);
621 
622 	/* Done with I2C */
623 	iic_release_bus(sc->sc_tag, I2C_F_POLL);
624 
625 	if (error != 0) {
626 		aprint_error_dev(sc->sc_dev,
627 		    "%s: failed to read rtc at 0x%x: %d\n",
628 		    __func__, reg, error);
629 		return 0;
630 	}
631 
632 	uint32_t v = (buf[3] << 24) | (buf[2] << 16) | (buf[1] << 8) | buf[0];
633 	*tp = v;
634 
635 	aprint_debug_dev(sc->sc_dev, "%s: cntr=0x%08"PRIx32"\n",
636 	    __func__, v);
637 
638 	return 1;
639 }
640 
641 static int
642 dsrtc_clock_write_timeval(struct dsrtc_softc *sc, time_t t)
643 {
644 	const struct dsrtc_model * const dm = &sc->sc_model;
645 	size_t buflen = dm->dm_rtc_size + 2;
646 	uint8_t buf[buflen];
647 	int error;
648 
649 	KASSERT((dm->dm_flags & DSRTC_FLAG_CLOCK_HOLD) == 0);
650 	KASSERT(dm->dm_ch_reg == dm->dm_rtc_start + 4);
651 
652 	buf[0] = dm->dm_rtc_start;
653 	buf[1] = (t >> 0) & 0xff;
654 	buf[2] = (t >> 8) & 0xff;
655 	buf[3] = (t >> 16) & 0xff;
656 	buf[4] = (t >> 24) & 0xff;
657 	buf[5] = 0;
658 
659 	if ((error = iic_acquire_bus(sc->sc_tag, I2C_F_POLL)) != 0) {
660 		aprint_error_dev(sc->sc_dev,
661 		    "%s: failed to acquire I2C bus: %d\n",
662 		    __func__, error);
663 		return 0;
664 	}
665 
666 	error = iic_exec(sc->sc_tag, I2C_OP_WRITE_WITH_STOP, sc->sc_address,
667 	    &buf, buflen, NULL, 0, I2C_F_POLL);
668 
669 	/* Done with I2C */
670 	iic_release_bus(sc->sc_tag, I2C_F_POLL);
671 
672 	/* send data */
673 	if (error != 0) {
674 		aprint_error_dev(sc->sc_dev,
675 		    "%s: failed to set time: %d\n",
676 		    __func__, error);
677 		return 0;
678 	}
679 
680 	return 1;
681 }
682 
683 static int
684 dsrtc_read_temp(struct dsrtc_softc *sc, uint32_t *temp)
685 {
686 	int error, tc;
687 	uint8_t reg = DS3232_TEMP_MSB;
688 	uint8_t buf[2];
689 
690 	if ((sc->sc_model.dm_flags & DSRTC_FLAG_TEMP) == 0)
691 		return ENOTSUP;
692 
693 	if ((error = iic_acquire_bus(sc->sc_tag, I2C_F_POLL)) != 0) {
694 		aprint_error_dev(sc->sc_dev,
695 		    "%s: failed to acquire I2C bus: %d\n",
696 		    __func__, error);
697 		return 0;
698 	}
699 
700 	/* read temperature registers: */
701 	error = iic_exec(sc->sc_tag, I2C_OP_READ_WITH_STOP, sc->sc_address,
702 	     &reg, 1, buf, 2, I2C_F_POLL);
703 
704 	/* Done with I2C */
705 	iic_release_bus(sc->sc_tag, I2C_F_POLL);
706 
707 	if (error != 0) {
708 		aprint_error_dev(sc->sc_dev,
709 		    "%s: failed to read temperature: %d\n",
710 		    __func__, error);
711 		return 0;
712 	}
713 
714 	/* convert to microkelvin */
715 	tc = buf[0] * 1000000 + (buf[1] >> 6) * 250000;
716 	*temp = tc + 273150000;
717 	return 1;
718 }
719 
720 static void
721 dsrtc_refresh(struct sysmon_envsys *sme, envsys_data_t *edata)
722 {
723 	struct dsrtc_softc *sc = sme->sme_cookie;
724 	uint32_t temp = 0;	/* XXX gcc */
725 
726 	if (dsrtc_read_temp(sc, &temp) == 0) {
727 		edata->state = ENVSYS_SINVALID;
728 		return;
729 	}
730 
731 	edata->value_cur = temp;
732 
733 	edata->state = ENVSYS_SVALID;
734 }
735