xref: /netbsd-src/sys/dev/i2c/ds1307.c (revision e89934bbf778a6d6d6894877c4da59d0c7835b0f)
1 /*	$NetBSD: ds1307.c,v 1.24 2016/10/18 18:54:54 aymeric 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 1.24 2016/10/18 18:54:54 aymeric 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_vbaten_reg;
61 	uint8_t dm_vbaten_value;
62 	uint8_t dm_rtc_start;
63 	uint8_t dm_rtc_size;
64 	uint8_t dm_nvram_start;
65 	uint8_t dm_nvram_size;
66 	uint8_t dm_flags;
67 #define	DSRTC_FLAG_CLOCK_HOLD		0x01
68 #define	DSRTC_FLAG_BCD			0x02
69 #define	DSRTC_FLAG_TEMP			0x04
70 #define DSRTC_FLAG_VBATEN		0x08
71 #define	DSRTC_FLAG_YEAR_START_2K	0x10
72 #define	DSRTC_FLAG_CLOCK_HOLD_REVERSED	0x20
73 };
74 
75 static const struct dsrtc_model dsrtc_models[] = {
76 	{
77 		.dm_model = 1307,
78 		.dm_ch_reg = DSXXXX_SECONDS,
79 		.dm_ch_value = DS1307_SECONDS_CH,
80 		.dm_rtc_start = DS1307_RTC_START,
81 		.dm_rtc_size = DS1307_RTC_SIZE,
82 		.dm_nvram_start = DS1307_NVRAM_START,
83 		.dm_nvram_size = DS1307_NVRAM_SIZE,
84 		.dm_flags = DSRTC_FLAG_BCD | DSRTC_FLAG_CLOCK_HOLD,
85 	}, {
86 		.dm_model = 1339,
87 		.dm_rtc_start = DS1339_RTC_START,
88 		.dm_rtc_size = DS1339_RTC_SIZE,
89 		.dm_flags = DSRTC_FLAG_BCD,
90 	}, {
91 		.dm_model = 1340,
92 		.dm_ch_reg = DSXXXX_SECONDS,
93 		.dm_ch_value = DS1340_SECONDS_EOSC,
94 		.dm_rtc_start = DS1340_RTC_START,
95 		.dm_rtc_size = DS1340_RTC_SIZE,
96 		.dm_flags = DSRTC_FLAG_BCD,
97 	}, {
98 		.dm_model = 1672,
99 		.dm_rtc_start = DS1672_RTC_START,
100 		.dm_rtc_size = DS1672_RTC_SIZE,
101 		.dm_ch_reg = DS1672_CONTROL,
102 		.dm_ch_value = DS1672_CONTROL_CH,
103 		.dm_flags = 0,
104 	}, {
105 		.dm_model = 3231,
106 		.dm_rtc_start = DS3232_RTC_START,
107 		.dm_rtc_size = DS3232_RTC_SIZE,
108 		/*
109 		 * XXX
110 		 * the DS3232 likely has the temperature sensor too but I can't
111 		 * easily verify or test that right now
112 		 */
113 		.dm_flags = DSRTC_FLAG_BCD | DSRTC_FLAG_TEMP,
114 	}, {
115 		.dm_model = 3232,
116 		.dm_rtc_start = DS3232_RTC_START,
117 		.dm_rtc_size = DS3232_RTC_SIZE,
118 		.dm_nvram_start = DS3232_NVRAM_START,
119 		.dm_nvram_size = DS3232_NVRAM_SIZE,
120 		.dm_flags = DSRTC_FLAG_BCD,
121 	}, {
122 		/* MCP7940 */
123 		.dm_model = 7940,
124 		.dm_rtc_start = DS1307_RTC_START,
125 		.dm_rtc_size = DS1307_RTC_SIZE,
126 		.dm_ch_reg = DSXXXX_SECONDS,
127 		.dm_ch_value = DS1307_SECONDS_CH,
128 		.dm_vbaten_reg = DSXXXX_DAY,
129 		.dm_vbaten_value = MCP7940_TOD_DAY_VBATEN,
130 		.dm_nvram_start = MCP7940_NVRAM_START,
131 		.dm_nvram_size = MCP7940_NVRAM_SIZE,
132 		.dm_flags = DSRTC_FLAG_BCD | DSRTC_FLAG_CLOCK_HOLD |
133 			DSRTC_FLAG_VBATEN | DSRTC_FLAG_CLOCK_HOLD_REVERSED,
134 	},
135 };
136 
137 struct dsrtc_softc {
138 	device_t sc_dev;
139 	i2c_tag_t sc_tag;
140 	uint8_t sc_address;
141 	bool sc_open;
142 	struct dsrtc_model sc_model;
143 	struct todr_chip_handle sc_todr;
144 	struct sysmon_envsys *sc_sme;
145 	envsys_data_t sc_sensor;
146 };
147 
148 static void	dsrtc_attach(device_t, device_t, void *);
149 static int	dsrtc_match(device_t, cfdata_t, void *);
150 
151 CFATTACH_DECL_NEW(dsrtc, sizeof(struct dsrtc_softc),
152     dsrtc_match, dsrtc_attach, NULL, NULL);
153 extern struct cfdriver dsrtc_cd;
154 
155 dev_type_open(dsrtc_open);
156 dev_type_close(dsrtc_close);
157 dev_type_read(dsrtc_read);
158 dev_type_write(dsrtc_write);
159 
160 const struct cdevsw dsrtc_cdevsw = {
161 	.d_open = dsrtc_open,
162 	.d_close = dsrtc_close,
163 	.d_read = dsrtc_read,
164 	.d_write = dsrtc_write,
165 	.d_ioctl = noioctl,
166 	.d_stop = nostop,
167 	.d_tty = notty,
168 	.d_poll = nopoll,
169 	.d_mmap = nommap,
170 	.d_kqfilter = nokqfilter,
171 	.d_discard = nodiscard,
172 	.d_flag = D_OTHER
173 };
174 
175 static int dsrtc_gettime_ymdhms(struct todr_chip_handle *, struct clock_ymdhms *);
176 static int dsrtc_settime_ymdhms(struct todr_chip_handle *, struct clock_ymdhms *);
177 static int dsrtc_clock_read_ymdhms(struct dsrtc_softc *, struct clock_ymdhms *);
178 static int dsrtc_clock_write_ymdhms(struct dsrtc_softc *, struct clock_ymdhms *);
179 
180 static int dsrtc_gettime_timeval(struct todr_chip_handle *, struct timeval *);
181 static int dsrtc_settime_timeval(struct todr_chip_handle *, struct timeval *);
182 static int dsrtc_clock_read_timeval(struct dsrtc_softc *, time_t *);
183 static int dsrtc_clock_write_timeval(struct dsrtc_softc *, time_t);
184 
185 static int dsrtc_read_temp(struct dsrtc_softc *, uint32_t *);
186 static void dsrtc_refresh(struct sysmon_envsys *, envsys_data_t *);
187 
188 static const struct dsrtc_model *
189 dsrtc_model(u_int model)
190 {
191 	/* no model given, assume it's a DS1307 (the first one) */
192 	if (model == 0)
193 		return &dsrtc_models[0];
194 
195 	for (const struct dsrtc_model *dm = dsrtc_models;
196 	     dm < dsrtc_models + __arraycount(dsrtc_models); dm++) {
197 		if (dm->dm_model == model)
198 			return dm;
199 	}
200 	return NULL;
201 }
202 
203 static int
204 dsrtc_match(device_t parent, cfdata_t cf, void *arg)
205 {
206 	struct i2c_attach_args *ia = arg;
207 
208 	if (ia->ia_name) {
209 		/* direct config - check name */
210 		if (strcmp(ia->ia_name, "dsrtc") == 0)
211 			return 1;
212 	} else {
213 		/* indirect config - check typical address */
214 		if (ia->ia_addr == DS1307_ADDR || ia->ia_addr == MCP7940_ADDR)
215 			return dsrtc_model(cf->cf_flags & 0xffff) != NULL;
216 	}
217 	return 0;
218 }
219 
220 static void
221 dsrtc_attach(device_t parent, device_t self, void *arg)
222 {
223 	struct dsrtc_softc *sc = device_private(self);
224 	struct i2c_attach_args *ia = arg;
225 	const struct dsrtc_model * const dm =
226 	    dsrtc_model(device_cfdata(self)->cf_flags);
227 
228 	aprint_naive(": Real-time Clock%s\n",
229 	    dm->dm_nvram_size > 0 ? "/NVRAM" : "");
230 	aprint_normal(": DS%u Real-time Clock%s\n", dm->dm_model,
231 	    dm->dm_nvram_size > 0 ? "/NVRAM" : "");
232 
233 	sc->sc_tag = ia->ia_tag;
234 	sc->sc_address = ia->ia_addr;
235 	sc->sc_model = *dm;
236 	sc->sc_dev = self;
237 	sc->sc_open = 0;
238 	sc->sc_todr.cookie = sc;
239 	if (dm->dm_flags & DSRTC_FLAG_BCD) {
240 		sc->sc_todr.todr_gettime_ymdhms = dsrtc_gettime_ymdhms;
241 		sc->sc_todr.todr_settime_ymdhms = dsrtc_settime_ymdhms;
242 	} else {
243 		sc->sc_todr.todr_gettime = dsrtc_gettime_timeval;
244 		sc->sc_todr.todr_settime = dsrtc_settime_timeval;
245 	}
246 	sc->sc_todr.todr_setwen = NULL;
247 
248 	todr_attach(&sc->sc_todr);
249 	if ((sc->sc_model.dm_flags & DSRTC_FLAG_TEMP) != 0) {
250 		int error;
251 
252 		sc->sc_sme = sysmon_envsys_create();
253 		sc->sc_sme->sme_name = device_xname(self);
254 		sc->sc_sme->sme_cookie = sc;
255 		sc->sc_sme->sme_refresh = dsrtc_refresh;
256 
257 		sc->sc_sensor.units =  ENVSYS_STEMP;
258 		sc->sc_sensor.state = ENVSYS_SINVALID;
259 		sc->sc_sensor.flags = 0;
260 		(void)strlcpy(sc->sc_sensor.desc, "temperature",
261 		    sizeof(sc->sc_sensor.desc));
262 
263 		if (sysmon_envsys_sensor_attach(sc->sc_sme, &sc->sc_sensor)) {
264 			aprint_error_dev(self, "unable to attach sensor\n");
265 			goto bad;
266 		}
267 
268 		error = sysmon_envsys_register(sc->sc_sme);
269 		if (error) {
270 			aprint_error_dev(self,
271 			    "error %d registering with sysmon\n", error);
272 			goto bad;
273 		}
274 	}
275 	return;
276 bad:
277 	sysmon_envsys_destroy(sc->sc_sme);
278 }
279 
280 /*ARGSUSED*/
281 int
282 dsrtc_open(dev_t dev, int flag, int fmt, struct lwp *l)
283 {
284 	struct dsrtc_softc *sc;
285 
286 	if ((sc = device_lookup_private(&dsrtc_cd, minor(dev))) == NULL)
287 		return ENXIO;
288 
289 	/* XXX: Locking */
290 	if (sc->sc_open)
291 		return EBUSY;
292 
293 	sc->sc_open = true;
294 	return 0;
295 }
296 
297 /*ARGSUSED*/
298 int
299 dsrtc_close(dev_t dev, int flag, int fmt, struct lwp *l)
300 {
301 	struct dsrtc_softc *sc;
302 
303 	if ((sc = device_lookup_private(&dsrtc_cd, minor(dev))) == NULL)
304 		return ENXIO;
305 
306 	sc->sc_open = false;
307 	return 0;
308 }
309 
310 /*ARGSUSED*/
311 int
312 dsrtc_read(dev_t dev, struct uio *uio, int flags)
313 {
314 	struct dsrtc_softc *sc;
315 	int error;
316 
317 	if ((sc = device_lookup_private(&dsrtc_cd, minor(dev))) == NULL)
318 		return ENXIO;
319 
320 	const struct dsrtc_model * const dm = &sc->sc_model;
321 	if (uio->uio_offset >= dm->dm_nvram_size)
322 		return EINVAL;
323 
324 	if ((error = iic_acquire_bus(sc->sc_tag, 0)) != 0)
325 		return error;
326 
327 	KASSERT(uio->uio_offset >= 0);
328 	while (uio->uio_resid && uio->uio_offset < dm->dm_nvram_size) {
329 		uint8_t ch, cmd;
330 		const u_int a = uio->uio_offset;
331 		cmd = a + dm->dm_nvram_start;
332 		if ((error = iic_exec(sc->sc_tag,
333 		    uio->uio_resid > 1 ? I2C_OP_READ : I2C_OP_READ_WITH_STOP,
334 		    sc->sc_address, &cmd, 1, &ch, 1, 0)) != 0) {
335 			iic_release_bus(sc->sc_tag, 0);
336 			aprint_error_dev(sc->sc_dev,
337 			    "%s: read failed at 0x%x: %d\n",
338 			    __func__, a, error);
339 			return error;
340 		}
341 		if ((error = uiomove(&ch, 1, uio)) != 0) {
342 			iic_release_bus(sc->sc_tag, 0);
343 			return error;
344 		}
345 	}
346 
347 	iic_release_bus(sc->sc_tag, 0);
348 
349 	return 0;
350 }
351 
352 /*ARGSUSED*/
353 int
354 dsrtc_write(dev_t dev, struct uio *uio, int flags)
355 {
356 	struct dsrtc_softc *sc;
357 	int error;
358 
359 	if ((sc = device_lookup_private(&dsrtc_cd, minor(dev))) == NULL)
360 		return ENXIO;
361 
362 	const struct dsrtc_model * const dm = &sc->sc_model;
363 	if (uio->uio_offset >= dm->dm_nvram_size)
364 		return EINVAL;
365 
366 	if ((error = iic_acquire_bus(sc->sc_tag, 0)) != 0)
367 		return error;
368 
369 	while (uio->uio_resid && uio->uio_offset < dm->dm_nvram_size) {
370 		uint8_t cmdbuf[2];
371 		const u_int a = (int)uio->uio_offset;
372 		cmdbuf[0] = a + dm->dm_nvram_start;
373 		if ((error = uiomove(&cmdbuf[1], 1, uio)) != 0)
374 			break;
375 
376 		if ((error = iic_exec(sc->sc_tag,
377 		    uio->uio_resid ? I2C_OP_WRITE : I2C_OP_WRITE_WITH_STOP,
378 		    sc->sc_address, cmdbuf, 1, &cmdbuf[1], 1, 0)) != 0) {
379 			aprint_error_dev(sc->sc_dev,
380 			    "%s: write failed at 0x%x: %d\n",
381 			    __func__, a, error);
382 			break;
383 		}
384 	}
385 
386 	iic_release_bus(sc->sc_tag, 0);
387 
388 	return error;
389 }
390 
391 static int
392 dsrtc_gettime_ymdhms(struct todr_chip_handle *ch, struct clock_ymdhms *dt)
393 {
394 	struct dsrtc_softc *sc = ch->cookie;
395 	struct clock_ymdhms check;
396 	int retries;
397 
398 	memset(dt, 0, sizeof(*dt));
399 	memset(&check, 0, sizeof(check));
400 
401 	/*
402 	 * Since we don't support Burst Read, we have to read the clock twice
403 	 * until we get two consecutive identical results.
404 	 */
405 	retries = 5;
406 	do {
407 		dsrtc_clock_read_ymdhms(sc, dt);
408 		dsrtc_clock_read_ymdhms(sc, &check);
409 	} while (memcmp(dt, &check, sizeof(check)) != 0 && --retries);
410 
411 	return 0;
412 }
413 
414 static int
415 dsrtc_settime_ymdhms(struct todr_chip_handle *ch, struct clock_ymdhms *dt)
416 {
417 	struct dsrtc_softc *sc = ch->cookie;
418 
419 	if (dsrtc_clock_write_ymdhms(sc, dt) == 0)
420 		return -1;
421 
422 	return 0;
423 }
424 
425 static int
426 dsrtc_clock_read_ymdhms(struct dsrtc_softc *sc, struct clock_ymdhms *dt)
427 {
428 	struct dsrtc_model * const dm = &sc->sc_model;
429 	uint8_t bcd[DSXXXX_RTC_SIZE], cmdbuf[1];
430 	int error;
431 
432 	KASSERT(DSXXXX_RTC_SIZE >= dm->dm_rtc_size);
433 
434 	if ((error = iic_acquire_bus(sc->sc_tag, I2C_F_POLL)) != 0) {
435 		aprint_error_dev(sc->sc_dev,
436 		    "%s: failed to acquire I2C bus: %d\n",
437 		    __func__, error);
438 		return 0;
439 	}
440 
441 	/* Read each RTC register in order. */
442 	for (u_int i = 0; !error && i < dm->dm_rtc_size; i++) {
443 		cmdbuf[0] = dm->dm_rtc_start + i;
444 
445 		error = iic_exec(sc->sc_tag, I2C_OP_READ_WITH_STOP,
446 		    sc->sc_address, cmdbuf, 1, &bcd[i], 1, I2C_F_POLL);
447 	}
448 
449 	/* Done with I2C */
450 	iic_release_bus(sc->sc_tag, I2C_F_POLL);
451 
452 	if (error != 0) {
453 		aprint_error_dev(sc->sc_dev,
454 		    "%s: failed to read rtc at 0x%x: %d\n",
455 		    __func__, cmdbuf[0], error);
456 		return 0;
457 	}
458 
459 	/*
460 	 * Convert the RTC's register values into something useable
461 	 */
462 	dt->dt_sec = bcdtobin(bcd[DSXXXX_SECONDS] & DSXXXX_SECONDS_MASK);
463 	dt->dt_min = bcdtobin(bcd[DSXXXX_MINUTES] & DSXXXX_MINUTES_MASK);
464 
465 	if ((bcd[DSXXXX_HOURS] & DSXXXX_HOURS_12HRS_MODE) != 0) {
466 		dt->dt_hour = bcdtobin(bcd[DSXXXX_HOURS] &
467 		    DSXXXX_HOURS_12MASK) % 12; /* 12AM -> 0, 12PM -> 12 */
468 		if (bcd[DSXXXX_HOURS] & DSXXXX_HOURS_12HRS_PM)
469 			dt->dt_hour += 12;
470 	} else
471 		dt->dt_hour = bcdtobin(bcd[DSXXXX_HOURS] &
472 		    DSXXXX_HOURS_24MASK);
473 
474 	dt->dt_day = bcdtobin(bcd[DSXXXX_DATE] & DSXXXX_DATE_MASK);
475 	dt->dt_mon = bcdtobin(bcd[DSXXXX_MONTH] & DSXXXX_MONTH_MASK);
476 
477 	/* XXX: Should be an MD way to specify EPOCH used by BIOS/Firmware */
478 	if (sc->sc_model.dm_flags & DSRTC_FLAG_YEAR_START_2K)
479 		dt->dt_year = bcdtobin(bcd[DSXXXX_YEAR]) + 2000;
480 	else {
481 		dt->dt_year = bcdtobin(bcd[DSXXXX_YEAR]) + POSIX_BASE_YEAR;
482 		if (bcd[DSXXXX_MONTH] & DSXXXX_MONTH_CENTURY)
483 			dt->dt_year += 100;
484 	}
485 
486 	return 1;
487 }
488 
489 static int
490 dsrtc_clock_write_ymdhms(struct dsrtc_softc *sc, struct clock_ymdhms *dt)
491 {
492 	struct dsrtc_model * const dm = &sc->sc_model;
493 	uint8_t bcd[DSXXXX_RTC_SIZE], cmdbuf[2];
494 	int error;
495 
496 	KASSERT(DSXXXX_RTC_SIZE >= dm->dm_rtc_size);
497 
498 	/*
499 	 * Convert our time representation into something the DSXXXX
500 	 * can understand.
501 	 */
502 	bcd[DSXXXX_SECONDS] = bintobcd(dt->dt_sec);
503 	bcd[DSXXXX_MINUTES] = bintobcd(dt->dt_min);
504 	bcd[DSXXXX_HOURS] = bintobcd(dt->dt_hour); /* DSXXXX_HOURS_12HRS_MODE=0 */
505 	bcd[DSXXXX_DATE] = bintobcd(dt->dt_day);
506 	bcd[DSXXXX_DAY] = bintobcd(dt->dt_wday);
507 	bcd[DSXXXX_MONTH] = bintobcd(dt->dt_mon);
508 	bcd[DSXXXX_YEAR] = bintobcd((dt->dt_year - POSIX_BASE_YEAR) % 100);
509 	if (dt->dt_year - POSIX_BASE_YEAR >= 100)
510 		bcd[DSXXXX_MONTH] |= DSXXXX_MONTH_CENTURY;
511 
512 	if ((error = iic_acquire_bus(sc->sc_tag, I2C_F_POLL)) != 0) {
513 		aprint_error_dev(sc->sc_dev,
514 		    "%s: failed to acquire I2C bus: %d\n",
515 		    __func__, error);
516 		return 0;
517 	}
518 
519 	/* Stop the clock */
520 	cmdbuf[0] = dm->dm_ch_reg;
521 
522 	if ((error = iic_exec(sc->sc_tag, I2C_OP_READ, sc->sc_address,
523 	    cmdbuf, 1, &cmdbuf[1], 1, I2C_F_POLL)) != 0) {
524 		iic_release_bus(sc->sc_tag, I2C_F_POLL);
525 		aprint_error_dev(sc->sc_dev,
526 		    "%s: failed to read Hold Clock: %d\n",
527 		    __func__, error);
528 		return 0;
529 	}
530 
531 	if (sc->sc_model.dm_flags & DSRTC_FLAG_CLOCK_HOLD_REVERSED)
532 		cmdbuf[1] &= ~dm->dm_ch_value;
533 	else
534 		cmdbuf[1] |= dm->dm_ch_value;
535 
536 	if ((error = iic_exec(sc->sc_tag, I2C_OP_WRITE, sc->sc_address,
537 	    cmdbuf, 1, &cmdbuf[1], 1, I2C_F_POLL)) != 0) {
538 		iic_release_bus(sc->sc_tag, I2C_F_POLL);
539 		aprint_error_dev(sc->sc_dev,
540 		    "%s: failed to write Hold Clock: %d\n",
541 		    __func__, error);
542 		return 0;
543 	}
544 
545 	/*
546 	 * Write registers in reverse order. The last write (to the Seconds
547 	 * register) will undo the Clock Hold, above.
548 	 */
549 	uint8_t op = I2C_OP_WRITE;
550 	for (signed int i = dm->dm_rtc_size - 1; i >= 0; i--) {
551 		cmdbuf[0] = dm->dm_rtc_start + i;
552 		if ((dm->dm_flags & DSRTC_FLAG_VBATEN) &&
553 				dm->dm_rtc_start + i == dm->dm_vbaten_reg)
554 			bcd[i] |= dm->dm_vbaten_value;
555 		if (dm->dm_rtc_start + i == dm->dm_ch_reg) {
556 			op = I2C_OP_WRITE_WITH_STOP;
557 			if (dm->dm_flags & DSRTC_FLAG_CLOCK_HOLD_REVERSED)
558 				bcd[i] |= dm->dm_ch_value;
559 		}
560 		if ((error = iic_exec(sc->sc_tag, op, sc->sc_address,
561 		    cmdbuf, 1, &bcd[i], 1, I2C_F_POLL)) != 0) {
562 			iic_release_bus(sc->sc_tag, I2C_F_POLL);
563 			aprint_error_dev(sc->sc_dev,
564 			    "%s: failed to write rtc at 0x%x: %d\n",
565 			    __func__, i, error);
566 			/* XXX: Clock Hold is likely still asserted! */
567 			return 0;
568 		}
569 	}
570 	/*
571 	 * If the clock hold register isn't the same register as seconds,
572 	 * we need to reeanble the clock.
573 	 */
574 	if (op != I2C_OP_WRITE_WITH_STOP) {
575 		cmdbuf[0] = dm->dm_ch_reg;
576 		if (dm->dm_flags & DSRTC_FLAG_CLOCK_HOLD_REVERSED)
577 			cmdbuf[1] |= dm->dm_ch_value;
578 		else
579 			cmdbuf[1] &= ~dm->dm_ch_value;
580 
581 		if ((error = iic_exec(sc->sc_tag, I2C_OP_WRITE_WITH_STOP,
582 		    sc->sc_address, cmdbuf, 1, &cmdbuf[1], 1,
583 		    I2C_F_POLL)) != 0) {
584 			iic_release_bus(sc->sc_tag, I2C_F_POLL);
585 			aprint_error_dev(sc->sc_dev,
586 			    "%s: failed to Hold Clock: %d\n",
587 			    __func__, error);
588 			return 0;
589 		}
590 	}
591 
592 	iic_release_bus(sc->sc_tag, I2C_F_POLL);
593 
594 	return 1;
595 }
596 
597 static int
598 dsrtc_gettime_timeval(struct todr_chip_handle *ch, struct timeval *tv)
599 {
600 	struct dsrtc_softc *sc = ch->cookie;
601 	struct timeval check;
602 	int retries;
603 
604 	memset(tv, 0, sizeof(*tv));
605 	memset(&check, 0, sizeof(check));
606 
607 	/*
608 	 * Since we don't support Burst Read, we have to read the clock twice
609 	 * until we get two consecutive identical results.
610 	 */
611 	retries = 5;
612 	do {
613 		dsrtc_clock_read_timeval(sc, &tv->tv_sec);
614 		dsrtc_clock_read_timeval(sc, &check.tv_sec);
615 	} while (memcmp(tv, &check, sizeof(check)) != 0 && --retries);
616 
617 	return 0;
618 }
619 
620 static int
621 dsrtc_settime_timeval(struct todr_chip_handle *ch, struct timeval *tv)
622 {
623 	struct dsrtc_softc *sc = ch->cookie;
624 
625 	if (dsrtc_clock_write_timeval(sc, tv->tv_sec) == 0)
626 		return -1;
627 
628 	return 0;
629 }
630 
631 /*
632  * The RTC probably has a nice Clock Burst Read/Write command, but we can't use
633  * it, since some I2C controllers don't support anything other than single-byte
634  * transfers.
635  */
636 static int
637 dsrtc_clock_read_timeval(struct dsrtc_softc *sc, time_t *tp)
638 {
639 	const struct dsrtc_model * const dm = &sc->sc_model;
640 	uint8_t buf[4];
641 	int error;
642 
643 	if ((error = iic_acquire_bus(sc->sc_tag, I2C_F_POLL)) != 0) {
644 		aprint_error_dev(sc->sc_dev,
645 		    "%s: failed to acquire I2C bus: %d\n",
646 		    __func__, error);
647 		return 0;
648 	}
649 
650 	/* read all registers: */
651 	uint8_t reg = dm->dm_rtc_start;
652 	error = iic_exec(sc->sc_tag, I2C_OP_READ_WITH_STOP, sc->sc_address,
653 	     &reg, 1, buf, 4, I2C_F_POLL);
654 
655 	/* Done with I2C */
656 	iic_release_bus(sc->sc_tag, I2C_F_POLL);
657 
658 	if (error != 0) {
659 		aprint_error_dev(sc->sc_dev,
660 		    "%s: failed to read rtc at 0x%x: %d\n",
661 		    __func__, reg, error);
662 		return 0;
663 	}
664 
665 	uint32_t v = (buf[3] << 24) | (buf[2] << 16) | (buf[1] << 8) | buf[0];
666 	*tp = v;
667 
668 	aprint_debug_dev(sc->sc_dev, "%s: cntr=0x%08"PRIx32"\n",
669 	    __func__, v);
670 
671 	return 1;
672 }
673 
674 static int
675 dsrtc_clock_write_timeval(struct dsrtc_softc *sc, time_t t)
676 {
677 	const struct dsrtc_model * const dm = &sc->sc_model;
678 	size_t buflen = dm->dm_rtc_size + 2;
679 	uint8_t buf[buflen];
680 	int error;
681 
682 	KASSERT((dm->dm_flags & DSRTC_FLAG_CLOCK_HOLD) == 0);
683 	KASSERT(dm->dm_ch_reg == dm->dm_rtc_start + 4);
684 
685 	buf[0] = dm->dm_rtc_start;
686 	buf[1] = (t >> 0) & 0xff;
687 	buf[2] = (t >> 8) & 0xff;
688 	buf[3] = (t >> 16) & 0xff;
689 	buf[4] = (t >> 24) & 0xff;
690 	buf[5] = 0;
691 
692 	if ((error = iic_acquire_bus(sc->sc_tag, I2C_F_POLL)) != 0) {
693 		aprint_error_dev(sc->sc_dev,
694 		    "%s: failed to acquire I2C bus: %d\n",
695 		    __func__, error);
696 		return 0;
697 	}
698 
699 	error = iic_exec(sc->sc_tag, I2C_OP_WRITE_WITH_STOP, sc->sc_address,
700 	    &buf, buflen, NULL, 0, I2C_F_POLL);
701 
702 	/* Done with I2C */
703 	iic_release_bus(sc->sc_tag, I2C_F_POLL);
704 
705 	/* send data */
706 	if (error != 0) {
707 		aprint_error_dev(sc->sc_dev,
708 		    "%s: failed to set time: %d\n",
709 		    __func__, error);
710 		return 0;
711 	}
712 
713 	return 1;
714 }
715 
716 static int
717 dsrtc_read_temp(struct dsrtc_softc *sc, uint32_t *temp)
718 {
719 	int error, tc;
720 	uint8_t reg = DS3232_TEMP_MSB;
721 	uint8_t buf[2];
722 
723 	if ((sc->sc_model.dm_flags & DSRTC_FLAG_TEMP) == 0)
724 		return ENOTSUP;
725 
726 	if ((error = iic_acquire_bus(sc->sc_tag, I2C_F_POLL)) != 0) {
727 		aprint_error_dev(sc->sc_dev,
728 		    "%s: failed to acquire I2C bus: %d\n",
729 		    __func__, error);
730 		return 0;
731 	}
732 
733 	/* read temperature registers: */
734 	error = iic_exec(sc->sc_tag, I2C_OP_READ_WITH_STOP, sc->sc_address,
735 	     &reg, 1, buf, 2, I2C_F_POLL);
736 
737 	/* Done with I2C */
738 	iic_release_bus(sc->sc_tag, I2C_F_POLL);
739 
740 	if (error != 0) {
741 		aprint_error_dev(sc->sc_dev,
742 		    "%s: failed to read temperature: %d\n",
743 		    __func__, error);
744 		return 0;
745 	}
746 
747 	/* convert to microkelvin */
748 	tc = buf[0] * 1000000 + (buf[1] >> 6) * 250000;
749 	*temp = tc + 273150000;
750 	return 1;
751 }
752 
753 static void
754 dsrtc_refresh(struct sysmon_envsys *sme, envsys_data_t *edata)
755 {
756 	struct dsrtc_softc *sc = sme->sme_cookie;
757 	uint32_t temp = 0;	/* XXX gcc */
758 
759 	if (dsrtc_read_temp(sc, &temp) == 0) {
760 		edata->state = ENVSYS_SINVALID;
761 		return;
762 	}
763 
764 	edata->value_cur = temp;
765 
766 	edata->state = ENVSYS_SVALID;
767 }
768