xref: /netbsd-src/sys/dev/i2c/ds1307.c (revision d909946ca08dceb44d7d0f22ec9488679695d976)
1 /*	$NetBSD: ds1307.c,v 1.22 2016/04/05 10:53:16 bouyer 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 1.22 2016/04/05 10:53:16 bouyer 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 = 1672,
87 		.dm_rtc_start = DS1672_RTC_START,
88 		.dm_rtc_size = DS1672_RTC_SIZE,
89 		.dm_ch_reg = DS1672_CONTROL,
90 		.dm_ch_value = DS1672_CONTROL_CH,
91 		.dm_flags = 0,
92 	}, {
93 		.dm_model = 3231,
94 		.dm_rtc_start = DS3232_RTC_START,
95 		.dm_rtc_size = DS3232_RTC_SIZE,
96 		/*
97 		 * XXX
98 		 * the DS3232 likely has the temperature sensor too but I can't
99 		 * easily verify or test that right now
100 		 */
101 		.dm_flags = DSRTC_FLAG_BCD | DSRTC_FLAG_TEMP,
102 	}, {
103 		.dm_model = 3232,
104 		.dm_rtc_start = DS3232_RTC_START,
105 		.dm_rtc_size = DS3232_RTC_SIZE,
106 		.dm_nvram_start = DS3232_NVRAM_START,
107 		.dm_nvram_size = DS3232_NVRAM_SIZE,
108 		.dm_flags = DSRTC_FLAG_BCD,
109 	},
110 };
111 
112 struct dsrtc_softc {
113 	device_t sc_dev;
114 	i2c_tag_t sc_tag;
115 	uint8_t sc_address;
116 	bool sc_open;
117 	struct dsrtc_model sc_model;
118 	struct todr_chip_handle sc_todr;
119 	struct sysmon_envsys *sc_sme;
120 	envsys_data_t sc_sensor;
121 };
122 
123 static void	dsrtc_attach(device_t, device_t, void *);
124 static int	dsrtc_match(device_t, cfdata_t, void *);
125 
126 CFATTACH_DECL_NEW(dsrtc, sizeof(struct dsrtc_softc),
127     dsrtc_match, dsrtc_attach, NULL, NULL);
128 extern struct cfdriver dsrtc_cd;
129 
130 dev_type_open(dsrtc_open);
131 dev_type_close(dsrtc_close);
132 dev_type_read(dsrtc_read);
133 dev_type_write(dsrtc_write);
134 
135 const struct cdevsw dsrtc_cdevsw = {
136 	.d_open = dsrtc_open,
137 	.d_close = dsrtc_close,
138 	.d_read = dsrtc_read,
139 	.d_write = dsrtc_write,
140 	.d_ioctl = noioctl,
141 	.d_stop = nostop,
142 	.d_tty = notty,
143 	.d_poll = nopoll,
144 	.d_mmap = nommap,
145 	.d_kqfilter = nokqfilter,
146 	.d_discard = nodiscard,
147 	.d_flag = D_OTHER
148 };
149 
150 static int dsrtc_gettime_ymdhms(struct todr_chip_handle *, struct clock_ymdhms *);
151 static int dsrtc_settime_ymdhms(struct todr_chip_handle *, struct clock_ymdhms *);
152 static int dsrtc_clock_read_ymdhms(struct dsrtc_softc *, struct clock_ymdhms *);
153 static int dsrtc_clock_write_ymdhms(struct dsrtc_softc *, struct clock_ymdhms *);
154 
155 static int dsrtc_gettime_timeval(struct todr_chip_handle *, struct timeval *);
156 static int dsrtc_settime_timeval(struct todr_chip_handle *, struct timeval *);
157 static int dsrtc_clock_read_timeval(struct dsrtc_softc *, time_t *);
158 static int dsrtc_clock_write_timeval(struct dsrtc_softc *, time_t);
159 
160 static int dsrtc_read_temp(struct dsrtc_softc *, uint32_t *);
161 static void dsrtc_refresh(struct sysmon_envsys *, envsys_data_t *);
162 
163 static const struct dsrtc_model *
164 dsrtc_model(u_int model)
165 {
166 	/* no model given, assume it's a DS1307 (the first one) */
167 	if (model == 0)
168 		return &dsrtc_models[0];
169 
170 	for (const struct dsrtc_model *dm = dsrtc_models;
171 	     dm < dsrtc_models + __arraycount(dsrtc_models); dm++) {
172 		if (dm->dm_model == model)
173 			return dm;
174 	}
175 	return NULL;
176 }
177 
178 static int
179 dsrtc_match(device_t parent, cfdata_t cf, void *arg)
180 {
181 	struct i2c_attach_args *ia = arg;
182 
183 	if (ia->ia_name) {
184 		/* direct config - check name */
185 		if (strcmp(ia->ia_name, "dsrtc") == 0)
186 			return 1;
187 	} else {
188 		/* indirect config - check typical address */
189 		if (ia->ia_addr == DS1307_ADDR)
190 			return dsrtc_model(cf->cf_flags & 0xffff) != NULL;
191 	}
192 	return 0;
193 }
194 
195 static void
196 dsrtc_attach(device_t parent, device_t self, void *arg)
197 {
198 	struct dsrtc_softc *sc = device_private(self);
199 	struct i2c_attach_args *ia = arg;
200 	const struct dsrtc_model * const dm =
201 	    dsrtc_model(device_cfdata(self)->cf_flags);
202 
203 	aprint_naive(": Real-time Clock%s\n",
204 	    dm->dm_nvram_size > 0 ? "/NVRAM" : "");
205 	aprint_normal(": DS%u Real-time Clock%s\n", dm->dm_model,
206 	    dm->dm_nvram_size > 0 ? "/NVRAM" : "");
207 
208 	sc->sc_tag = ia->ia_tag;
209 	sc->sc_address = ia->ia_addr;
210 	sc->sc_model = *dm;
211 	sc->sc_dev = self;
212 	sc->sc_open = 0;
213 	sc->sc_todr.cookie = sc;
214 	if (dm->dm_flags & DSRTC_FLAG_BCD) {
215 		sc->sc_todr.todr_gettime_ymdhms = dsrtc_gettime_ymdhms;
216 		sc->sc_todr.todr_settime_ymdhms = dsrtc_settime_ymdhms;
217 	} else {
218 		sc->sc_todr.todr_gettime = dsrtc_gettime_timeval;
219 		sc->sc_todr.todr_settime = dsrtc_settime_timeval;
220 	}
221 	sc->sc_todr.todr_setwen = NULL;
222 
223 	todr_attach(&sc->sc_todr);
224 	if ((sc->sc_model.dm_flags & DSRTC_FLAG_TEMP) != 0) {
225 		int error;
226 
227 		sc->sc_sme = sysmon_envsys_create();
228 		sc->sc_sme->sme_name = device_xname(self);
229 		sc->sc_sme->sme_cookie = sc;
230 		sc->sc_sme->sme_refresh = dsrtc_refresh;
231 
232 		sc->sc_sensor.units =  ENVSYS_STEMP;
233 		sc->sc_sensor.state = ENVSYS_SINVALID;
234 		sc->sc_sensor.flags = 0;
235 		(void)strlcpy(sc->sc_sensor.desc, "temperature",
236 		    sizeof(sc->sc_sensor.desc));
237 
238 		if (sysmon_envsys_sensor_attach(sc->sc_sme, &sc->sc_sensor)) {
239 			aprint_error_dev(self, "unable to attach sensor\n");
240 			goto bad;
241 		}
242 
243 		error = sysmon_envsys_register(sc->sc_sme);
244 		if (error) {
245 			aprint_error_dev(self,
246 			    "error %d registering with sysmon\n", error);
247 			goto bad;
248 		}
249 	}
250 	return;
251 bad:
252 	sysmon_envsys_destroy(sc->sc_sme);
253 }
254 
255 /*ARGSUSED*/
256 int
257 dsrtc_open(dev_t dev, int flag, int fmt, struct lwp *l)
258 {
259 	struct dsrtc_softc *sc;
260 
261 	if ((sc = device_lookup_private(&dsrtc_cd, minor(dev))) == NULL)
262 		return ENXIO;
263 
264 	/* XXX: Locking */
265 	if (sc->sc_open)
266 		return EBUSY;
267 
268 	sc->sc_open = true;
269 	return 0;
270 }
271 
272 /*ARGSUSED*/
273 int
274 dsrtc_close(dev_t dev, int flag, int fmt, struct lwp *l)
275 {
276 	struct dsrtc_softc *sc;
277 
278 	if ((sc = device_lookup_private(&dsrtc_cd, minor(dev))) == NULL)
279 		return ENXIO;
280 
281 	sc->sc_open = false;
282 	return 0;
283 }
284 
285 /*ARGSUSED*/
286 int
287 dsrtc_read(dev_t dev, struct uio *uio, int flags)
288 {
289 	struct dsrtc_softc *sc;
290 	int error;
291 
292 	if ((sc = device_lookup_private(&dsrtc_cd, minor(dev))) == NULL)
293 		return ENXIO;
294 
295 	const struct dsrtc_model * const dm = &sc->sc_model;
296 	if (uio->uio_offset >= dm->dm_nvram_size)
297 		return EINVAL;
298 
299 	if ((error = iic_acquire_bus(sc->sc_tag, 0)) != 0)
300 		return error;
301 
302 	KASSERT(uio->uio_offset >= 0);
303 	while (uio->uio_resid && uio->uio_offset < dm->dm_nvram_size) {
304 		uint8_t ch, cmd;
305 		const u_int a = uio->uio_offset;
306 		cmd = a + dm->dm_nvram_start;
307 		if ((error = iic_exec(sc->sc_tag,
308 		    uio->uio_resid > 1 ? I2C_OP_READ : I2C_OP_READ_WITH_STOP,
309 		    sc->sc_address, &cmd, 1, &ch, 1, 0)) != 0) {
310 			iic_release_bus(sc->sc_tag, 0);
311 			aprint_error_dev(sc->sc_dev,
312 			    "%s: read failed at 0x%x: %d\n",
313 			    __func__, a, error);
314 			return error;
315 		}
316 		if ((error = uiomove(&ch, 1, uio)) != 0) {
317 			iic_release_bus(sc->sc_tag, 0);
318 			return error;
319 		}
320 	}
321 
322 	iic_release_bus(sc->sc_tag, 0);
323 
324 	return 0;
325 }
326 
327 /*ARGSUSED*/
328 int
329 dsrtc_write(dev_t dev, struct uio *uio, int flags)
330 {
331 	struct dsrtc_softc *sc;
332 	int error;
333 
334 	if ((sc = device_lookup_private(&dsrtc_cd, minor(dev))) == NULL)
335 		return ENXIO;
336 
337 	const struct dsrtc_model * const dm = &sc->sc_model;
338 	if (uio->uio_offset >= dm->dm_nvram_size)
339 		return EINVAL;
340 
341 	if ((error = iic_acquire_bus(sc->sc_tag, 0)) != 0)
342 		return error;
343 
344 	while (uio->uio_resid && uio->uio_offset < dm->dm_nvram_size) {
345 		uint8_t cmdbuf[2];
346 		const u_int a = (int)uio->uio_offset;
347 		cmdbuf[0] = a + dm->dm_nvram_start;
348 		if ((error = uiomove(&cmdbuf[1], 1, uio)) != 0)
349 			break;
350 
351 		if ((error = iic_exec(sc->sc_tag,
352 		    uio->uio_resid ? I2C_OP_WRITE : I2C_OP_WRITE_WITH_STOP,
353 		    sc->sc_address, cmdbuf, 1, &cmdbuf[1], 1, 0)) != 0) {
354 			aprint_error_dev(sc->sc_dev,
355 			    "%s: write failed at 0x%x: %d\n",
356 			    __func__, a, error);
357 			break;
358 		}
359 	}
360 
361 	iic_release_bus(sc->sc_tag, 0);
362 
363 	return error;
364 }
365 
366 static int
367 dsrtc_gettime_ymdhms(struct todr_chip_handle *ch, struct clock_ymdhms *dt)
368 {
369 	struct dsrtc_softc *sc = ch->cookie;
370 	struct clock_ymdhms check;
371 	int retries;
372 
373 	memset(dt, 0, sizeof(*dt));
374 	memset(&check, 0, sizeof(check));
375 
376 	/*
377 	 * Since we don't support Burst Read, we have to read the clock twice
378 	 * until we get two consecutive identical results.
379 	 */
380 	retries = 5;
381 	do {
382 		dsrtc_clock_read_ymdhms(sc, dt);
383 		dsrtc_clock_read_ymdhms(sc, &check);
384 	} while (memcmp(dt, &check, sizeof(check)) != 0 && --retries);
385 
386 	return 0;
387 }
388 
389 static int
390 dsrtc_settime_ymdhms(struct todr_chip_handle *ch, struct clock_ymdhms *dt)
391 {
392 	struct dsrtc_softc *sc = ch->cookie;
393 
394 	if (dsrtc_clock_write_ymdhms(sc, dt) == 0)
395 		return -1;
396 
397 	return 0;
398 }
399 
400 static int
401 dsrtc_clock_read_ymdhms(struct dsrtc_softc *sc, struct clock_ymdhms *dt)
402 {
403 	struct dsrtc_model * const dm = &sc->sc_model;
404 	uint8_t bcd[DSXXXX_RTC_SIZE], cmdbuf[1];
405 	int error;
406 
407 	KASSERT(DSXXXX_RTC_SIZE >= dm->dm_rtc_size);
408 
409 	if ((error = iic_acquire_bus(sc->sc_tag, I2C_F_POLL)) != 0) {
410 		aprint_error_dev(sc->sc_dev,
411 		    "%s: failed to acquire I2C bus: %d\n",
412 		    __func__, error);
413 		return 0;
414 	}
415 
416 	/* Read each RTC register in order. */
417 	for (u_int i = 0; !error && i < dm->dm_rtc_size; i++) {
418 		cmdbuf[0] = dm->dm_rtc_start + i;
419 
420 		error = iic_exec(sc->sc_tag, I2C_OP_READ_WITH_STOP,
421 		    sc->sc_address, cmdbuf, 1, &bcd[i], 1, I2C_F_POLL);
422 	}
423 
424 	/* Done with I2C */
425 	iic_release_bus(sc->sc_tag, I2C_F_POLL);
426 
427 	if (error != 0) {
428 		aprint_error_dev(sc->sc_dev,
429 		    "%s: failed to read rtc at 0x%x: %d\n",
430 		    __func__, cmdbuf[0], error);
431 		return 0;
432 	}
433 
434 	/*
435 	 * Convert the RTC's register values into something useable
436 	 */
437 	dt->dt_sec = bcdtobin(bcd[DSXXXX_SECONDS] & DSXXXX_SECONDS_MASK);
438 	dt->dt_min = bcdtobin(bcd[DSXXXX_MINUTES] & DSXXXX_MINUTES_MASK);
439 
440 	if ((bcd[DSXXXX_HOURS] & DSXXXX_HOURS_12HRS_MODE) != 0) {
441 		dt->dt_hour = bcdtobin(bcd[DSXXXX_HOURS] &
442 		    DSXXXX_HOURS_12MASK) % 12; /* 12AM -> 0, 12PM -> 12 */
443 		if (bcd[DSXXXX_HOURS] & DSXXXX_HOURS_12HRS_PM)
444 			dt->dt_hour += 12;
445 	} else
446 		dt->dt_hour = bcdtobin(bcd[DSXXXX_HOURS] &
447 		    DSXXXX_HOURS_24MASK);
448 
449 	dt->dt_day = bcdtobin(bcd[DSXXXX_DATE] & DSXXXX_DATE_MASK);
450 	dt->dt_mon = bcdtobin(bcd[DSXXXX_MONTH] & DSXXXX_MONTH_MASK);
451 
452 	/* XXX: Should be an MD way to specify EPOCH used by BIOS/Firmware */
453 	dt->dt_year = bcdtobin(bcd[DSXXXX_YEAR]) + POSIX_BASE_YEAR;
454 	if (bcd[DSXXXX_MONTH] & DSXXXX_MONTH_CENTURY)
455 		dt->dt_year += 100;
456 
457 	return 1;
458 }
459 
460 static int
461 dsrtc_clock_write_ymdhms(struct dsrtc_softc *sc, struct clock_ymdhms *dt)
462 {
463 	struct dsrtc_model * const dm = &sc->sc_model;
464 	uint8_t bcd[DSXXXX_RTC_SIZE], cmdbuf[2];
465 	int error;
466 
467 	KASSERT(DSXXXX_RTC_SIZE >= dm->dm_rtc_size);
468 
469 	/*
470 	 * Convert our time representation into something the DSXXXX
471 	 * can understand.
472 	 */
473 	bcd[DSXXXX_SECONDS] = bintobcd(dt->dt_sec);
474 	bcd[DSXXXX_MINUTES] = bintobcd(dt->dt_min);
475 	bcd[DSXXXX_HOURS] = bintobcd(dt->dt_hour); /* DSXXXX_HOURS_12HRS_MODE=0 */
476 	bcd[DSXXXX_DATE] = bintobcd(dt->dt_day);
477 	bcd[DSXXXX_DAY] = bintobcd(dt->dt_wday);
478 	bcd[DSXXXX_MONTH] = bintobcd(dt->dt_mon);
479 	bcd[DSXXXX_YEAR] = bintobcd((dt->dt_year - POSIX_BASE_YEAR) % 100);
480 	if (dt->dt_year - POSIX_BASE_YEAR >= 100)
481 		bcd[DSXXXX_MONTH] |= DSXXXX_MONTH_CENTURY;
482 
483 	if ((error = iic_acquire_bus(sc->sc_tag, I2C_F_POLL)) != 0) {
484 		aprint_error_dev(sc->sc_dev,
485 		    "%s: failed to acquire I2C bus: %d\n",
486 		    __func__, error);
487 		return 0;
488 	}
489 
490 	/* Stop the clock */
491 	cmdbuf[0] = dm->dm_ch_reg;
492 
493 	if ((error = iic_exec(sc->sc_tag, I2C_OP_READ, sc->sc_address,
494 	    cmdbuf, 1, &cmdbuf[1], 1, I2C_F_POLL)) != 0) {
495 		iic_release_bus(sc->sc_tag, I2C_F_POLL);
496 		aprint_error_dev(sc->sc_dev,
497 		    "%s: failed to read Hold Clock: %d\n",
498 		    __func__, error);
499 		return 0;
500 	}
501 
502 	cmdbuf[1] |= dm->dm_ch_value;
503 
504 	if ((error = iic_exec(sc->sc_tag, I2C_OP_WRITE, sc->sc_address,
505 	    cmdbuf, 1, &cmdbuf[1], 1, I2C_F_POLL)) != 0) {
506 		iic_release_bus(sc->sc_tag, I2C_F_POLL);
507 		aprint_error_dev(sc->sc_dev,
508 		    "%s: failed to write Hold Clock: %d\n",
509 		    __func__, error);
510 		return 0;
511 	}
512 
513 	/*
514 	 * Write registers in reverse order. The last write (to the Seconds
515 	 * register) will undo the Clock Hold, above.
516 	 */
517 	uint8_t op = I2C_OP_WRITE;
518 	for (signed int i = dm->dm_rtc_size - 1; i >= 0; i--) {
519 		cmdbuf[0] = dm->dm_rtc_start + i;
520 		if (dm->dm_rtc_start + i == dm->dm_ch_reg) {
521 			op = I2C_OP_WRITE_WITH_STOP;
522 		}
523 		if ((error = iic_exec(sc->sc_tag, op, sc->sc_address,
524 		    cmdbuf, 1, &bcd[i], 1, I2C_F_POLL)) != 0) {
525 			iic_release_bus(sc->sc_tag, I2C_F_POLL);
526 			aprint_error_dev(sc->sc_dev,
527 			    "%s: failed to write rtc at 0x%x: %d\n",
528 			    __func__, i, error);
529 			/* XXX: Clock Hold is likely still asserted! */
530 			return 0;
531 		}
532 	}
533 	/*
534 	 * If the clock hold register isn't the same register as seconds,
535 	 * we need to reeanble the clock.
536 	 */
537 	if (op != I2C_OP_WRITE_WITH_STOP) {
538 		cmdbuf[0] = dm->dm_ch_reg;
539 		cmdbuf[1] &= ~dm->dm_ch_value;
540 
541 		if ((error = iic_exec(sc->sc_tag, I2C_OP_WRITE_WITH_STOP,
542 		    sc->sc_address, cmdbuf, 1, &cmdbuf[1], 1,
543 		    I2C_F_POLL)) != 0) {
544 			iic_release_bus(sc->sc_tag, I2C_F_POLL);
545 			aprint_error_dev(sc->sc_dev,
546 			    "%s: failed to Hold Clock: %d\n",
547 			    __func__, error);
548 			return 0;
549 		}
550 	}
551 
552 	iic_release_bus(sc->sc_tag, I2C_F_POLL);
553 
554 	return 1;
555 }
556 
557 static int
558 dsrtc_gettime_timeval(struct todr_chip_handle *ch, struct timeval *tv)
559 {
560 	struct dsrtc_softc *sc = ch->cookie;
561 	struct timeval check;
562 	int retries;
563 
564 	memset(tv, 0, sizeof(*tv));
565 	memset(&check, 0, sizeof(check));
566 
567 	/*
568 	 * Since we don't support Burst Read, we have to read the clock twice
569 	 * until we get two consecutive identical results.
570 	 */
571 	retries = 5;
572 	do {
573 		dsrtc_clock_read_timeval(sc, &tv->tv_sec);
574 		dsrtc_clock_read_timeval(sc, &check.tv_sec);
575 	} while (memcmp(tv, &check, sizeof(check)) != 0 && --retries);
576 
577 	return 0;
578 }
579 
580 static int
581 dsrtc_settime_timeval(struct todr_chip_handle *ch, struct timeval *tv)
582 {
583 	struct dsrtc_softc *sc = ch->cookie;
584 
585 	if (dsrtc_clock_write_timeval(sc, tv->tv_sec) == 0)
586 		return -1;
587 
588 	return 0;
589 }
590 
591 /*
592  * The RTC probably has a nice Clock Burst Read/Write command, but we can't use
593  * it, since some I2C controllers don't support anything other than single-byte
594  * transfers.
595  */
596 static int
597 dsrtc_clock_read_timeval(struct dsrtc_softc *sc, time_t *tp)
598 {
599 	const struct dsrtc_model * const dm = &sc->sc_model;
600 	uint8_t buf[4];
601 	int error;
602 
603 	if ((error = iic_acquire_bus(sc->sc_tag, I2C_F_POLL)) != 0) {
604 		aprint_error_dev(sc->sc_dev,
605 		    "%s: failed to acquire I2C bus: %d\n",
606 		    __func__, error);
607 		return 0;
608 	}
609 
610 	/* read all registers: */
611 	uint8_t reg = dm->dm_rtc_start;
612 	error = iic_exec(sc->sc_tag, I2C_OP_READ_WITH_STOP, sc->sc_address,
613 	     &reg, 1, buf, 4, I2C_F_POLL);
614 
615 	/* Done with I2C */
616 	iic_release_bus(sc->sc_tag, I2C_F_POLL);
617 
618 	if (error != 0) {
619 		aprint_error_dev(sc->sc_dev,
620 		    "%s: failed to read rtc at 0x%x: %d\n",
621 		    __func__, reg, error);
622 		return 0;
623 	}
624 
625 	uint32_t v = (buf[3] << 24) | (buf[2] << 16) | (buf[1] << 8) | buf[0];
626 	*tp = v;
627 
628 	aprint_debug_dev(sc->sc_dev, "%s: cntr=0x%08"PRIx32"\n",
629 	    __func__, v);
630 
631 	return 1;
632 }
633 
634 static int
635 dsrtc_clock_write_timeval(struct dsrtc_softc *sc, time_t t)
636 {
637 	const struct dsrtc_model * const dm = &sc->sc_model;
638 	size_t buflen = dm->dm_rtc_size + 2;
639 	uint8_t buf[buflen];
640 	int error;
641 
642 	KASSERT((dm->dm_flags & DSRTC_FLAG_CLOCK_HOLD) == 0);
643 	KASSERT(dm->dm_ch_reg == dm->dm_rtc_start + 4);
644 
645 	buf[0] = dm->dm_rtc_start;
646 	buf[1] = (t >> 0) & 0xff;
647 	buf[2] = (t >> 8) & 0xff;
648 	buf[3] = (t >> 16) & 0xff;
649 	buf[4] = (t >> 24) & 0xff;
650 	buf[5] = 0;
651 
652 	if ((error = iic_acquire_bus(sc->sc_tag, I2C_F_POLL)) != 0) {
653 		aprint_error_dev(sc->sc_dev,
654 		    "%s: failed to acquire I2C bus: %d\n",
655 		    __func__, error);
656 		return 0;
657 	}
658 
659 	error = iic_exec(sc->sc_tag, I2C_OP_WRITE_WITH_STOP, sc->sc_address,
660 	    &buf, buflen, NULL, 0, I2C_F_POLL);
661 
662 	/* Done with I2C */
663 	iic_release_bus(sc->sc_tag, I2C_F_POLL);
664 
665 	/* send data */
666 	if (error != 0) {
667 		aprint_error_dev(sc->sc_dev,
668 		    "%s: failed to set time: %d\n",
669 		    __func__, error);
670 		return 0;
671 	}
672 
673 	return 1;
674 }
675 
676 static int
677 dsrtc_read_temp(struct dsrtc_softc *sc, uint32_t *temp)
678 {
679 	int error, tc;
680 	uint8_t reg = DS3232_TEMP_MSB;
681 	uint8_t buf[2];
682 
683 	if ((sc->sc_model.dm_flags & DSRTC_FLAG_TEMP) == 0)
684 		return ENOTSUP;
685 
686 	if ((error = iic_acquire_bus(sc->sc_tag, I2C_F_POLL)) != 0) {
687 		aprint_error_dev(sc->sc_dev,
688 		    "%s: failed to acquire I2C bus: %d\n",
689 		    __func__, error);
690 		return 0;
691 	}
692 
693 	/* read temperature registers: */
694 	error = iic_exec(sc->sc_tag, I2C_OP_READ_WITH_STOP, sc->sc_address,
695 	     &reg, 1, buf, 2, I2C_F_POLL);
696 
697 	/* Done with I2C */
698 	iic_release_bus(sc->sc_tag, I2C_F_POLL);
699 
700 	if (error != 0) {
701 		aprint_error_dev(sc->sc_dev,
702 		    "%s: failed to read temperature: %d\n",
703 		    __func__, error);
704 		return 0;
705 	}
706 
707 	/* convert to microkelvin */
708 	tc = buf[0] * 1000000 + (buf[1] >> 6) * 250000;
709 	*temp = tc + 273150000;
710 	return 1;
711 }
712 
713 static void
714 dsrtc_refresh(struct sysmon_envsys *sme, envsys_data_t *edata)
715 {
716 	struct dsrtc_softc *sc = sme->sme_cookie;
717 	uint32_t temp = 0;	/* XXX gcc */
718 
719 	if (dsrtc_read_temp(sc, &temp) == 0) {
720 		edata->state = ENVSYS_SINVALID;
721 		return;
722 	}
723 
724 	edata->value_cur = temp;
725 
726 	edata->state = ENVSYS_SVALID;
727 }
728