xref: /netbsd-src/sys/dev/i2c/ds1307.c (revision b7b7574d3bf8eeb51a1fa3977b59142ec6434a55)
1 /*	$NetBSD: ds1307.c,v 1.17 2014/03/16 05:20:27 dholland 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 1.17 2014/03/16 05:20:27 dholland 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 
55 struct dsrtc_model {
56 	uint16_t dm_model;
57 	uint8_t dm_ch_reg;
58 	uint8_t dm_ch_value;
59 	uint8_t dm_rtc_start;
60 	uint8_t dm_rtc_size;
61 	uint8_t dm_nvram_start;
62 	uint8_t dm_nvram_size;
63 	uint8_t dm_flags;
64 #define	DSRTC_FLAG_CLOCK_HOLD	1
65 #define	DSRTC_FLAG_BCD		2
66 };
67 
68 static const struct dsrtc_model dsrtc_models[] = {
69 	{
70 		.dm_model = 1307,
71 		.dm_ch_reg = DSXXXX_SECONDS,
72 		.dm_ch_value = DS1307_SECONDS_CH,
73 		.dm_rtc_start = DS1307_RTC_START,
74 		.dm_rtc_size = DS1307_RTC_SIZE,
75 		.dm_nvram_start = DS1307_NVRAM_START,
76 		.dm_nvram_size = DS1307_NVRAM_SIZE,
77 		.dm_flags = DSRTC_FLAG_BCD | DSRTC_FLAG_CLOCK_HOLD,
78 	}, {
79 		.dm_model = 1339,
80 		.dm_rtc_start = DS1339_RTC_START,
81 		.dm_rtc_size = DS1339_RTC_SIZE,
82 		.dm_flags = DSRTC_FLAG_BCD,
83 	}, {
84 		.dm_model = 1672,
85 		.dm_rtc_start = DS1672_RTC_START,
86 		.dm_rtc_size = DS1672_RTC_SIZE,
87 		.dm_flags = 0,
88 	}, {
89 		.dm_model = 3232,
90 		.dm_rtc_start = DS3232_RTC_START,
91 		.dm_rtc_size = DS3232_RTC_SIZE,
92 		.dm_nvram_start = DS3232_NVRAM_START,
93 		.dm_nvram_size = DS3232_NVRAM_SIZE,
94 		.dm_flags = DSRTC_FLAG_BCD,
95 	},
96 };
97 
98 struct dsrtc_softc {
99 	device_t sc_dev;
100 	i2c_tag_t sc_tag;
101 	uint8_t sc_address;
102 	bool sc_open;
103 	struct dsrtc_model sc_model;
104 	struct todr_chip_handle sc_todr;
105 };
106 
107 static void	dsrtc_attach(device_t, device_t, void *);
108 static int	dsrtc_match(device_t, cfdata_t, void *);
109 
110 CFATTACH_DECL_NEW(dsrtc, sizeof(struct dsrtc_softc),
111     dsrtc_match, dsrtc_attach, NULL, NULL);
112 extern struct cfdriver dsrtc_cd;
113 
114 dev_type_open(dsrtc_open);
115 dev_type_close(dsrtc_close);
116 dev_type_read(dsrtc_read);
117 dev_type_write(dsrtc_write);
118 
119 const struct cdevsw dsrtc_cdevsw = {
120 	.d_open = dsrtc_open,
121 	.d_close = dsrtc_close,
122 	.d_read = dsrtc_read,
123 	.d_write = dsrtc_write,
124 	.d_ioctl = noioctl,
125 	.d_stop = nostop,
126 	.d_tty = notty,
127 	.d_poll = nopoll,
128 	.d_mmap = nommap,
129 	.d_kqfilter = nokqfilter,
130 	.d_flag = D_OTHER
131 };
132 
133 static int dsrtc_gettime_ymdhms(struct todr_chip_handle *, struct clock_ymdhms *);
134 static int dsrtc_settime_ymdhms(struct todr_chip_handle *, struct clock_ymdhms *);
135 static int dsrtc_clock_read_ymdhms(struct dsrtc_softc *, struct clock_ymdhms *);
136 static int dsrtc_clock_write_ymdhms(struct dsrtc_softc *, struct clock_ymdhms *);
137 
138 static int dsrtc_gettime_timeval(struct todr_chip_handle *, struct timeval *);
139 static int dsrtc_settime_timeval(struct todr_chip_handle *, struct timeval *);
140 static int dsrtc_clock_read_timeval(struct dsrtc_softc *, time_t *);
141 static int dsrtc_clock_write_timeval(struct dsrtc_softc *, time_t);
142 
143 static const struct dsrtc_model *
144 dsrtc_model(u_int model)
145 {
146 	/* no model given, assume it's a DS1307 (the first one) */
147 	if (model == 0)
148 		return &dsrtc_models[0];
149 
150 	for (const struct dsrtc_model *dm = dsrtc_models;
151 	     dm < dsrtc_models + __arraycount(dsrtc_models); dm++) {
152 		if (dm->dm_model == model)
153 			return dm;
154 	}
155 	return NULL;
156 }
157 
158 static int
159 dsrtc_match(device_t parent, cfdata_t cf, void *arg)
160 {
161 	struct i2c_attach_args *ia = arg;
162 
163 	if (ia->ia_name) {
164 		/* direct config - check name */
165 		if (strcmp(ia->ia_name, "dsrtc") == 0)
166 			return 1;
167 	} else {
168 		/* indirect config - check typical address */
169 		if (ia->ia_addr == DS1307_ADDR)
170 			return dsrtc_model(cf->cf_flags & 0xffff) != NULL;
171 	}
172 	return 0;
173 }
174 
175 static void
176 dsrtc_attach(device_t parent, device_t self, void *arg)
177 {
178 	struct dsrtc_softc *sc = device_private(self);
179 	struct i2c_attach_args *ia = arg;
180 	const struct dsrtc_model * const dm =
181 	    dsrtc_model(device_cfdata(self)->cf_flags);
182 
183 	aprint_naive(": Real-time Clock%s\n",
184 	    dm->dm_nvram_size > 0 ? "/NVRAM" : "");
185 	aprint_normal(": DS%u Real-time Clock%s\n", dm->dm_model,
186 	    dm->dm_nvram_size > 0 ? "/NVRAM" : "");
187 
188 	sc->sc_tag = ia->ia_tag;
189 	sc->sc_address = ia->ia_addr;
190 	sc->sc_model = *dm;
191 	sc->sc_dev = self;
192 	sc->sc_open = 0;
193 	sc->sc_todr.cookie = sc;
194 	if (dm->dm_flags & DSRTC_FLAG_BCD) {
195 		sc->sc_todr.todr_gettime_ymdhms = dsrtc_gettime_ymdhms;
196 		sc->sc_todr.todr_settime_ymdhms = dsrtc_settime_ymdhms;
197 	} else {
198 		sc->sc_todr.todr_gettime = dsrtc_gettime_timeval;
199 		sc->sc_todr.todr_settime = dsrtc_settime_timeval;
200 	}
201 	sc->sc_todr.todr_setwen = NULL;
202 
203 	todr_attach(&sc->sc_todr);
204 }
205 
206 /*ARGSUSED*/
207 int
208 dsrtc_open(dev_t dev, int flag, int fmt, struct lwp *l)
209 {
210 	struct dsrtc_softc *sc;
211 
212 	if ((sc = device_lookup_private(&dsrtc_cd, minor(dev))) == NULL)
213 		return ENXIO;
214 
215 	/* XXX: Locking */
216 	if (sc->sc_open)
217 		return EBUSY;
218 
219 	sc->sc_open = true;
220 	return 0;
221 }
222 
223 /*ARGSUSED*/
224 int
225 dsrtc_close(dev_t dev, int flag, int fmt, struct lwp *l)
226 {
227 	struct dsrtc_softc *sc;
228 
229 	if ((sc = device_lookup_private(&dsrtc_cd, minor(dev))) == NULL)
230 		return ENXIO;
231 
232 	sc->sc_open = false;
233 	return 0;
234 }
235 
236 /*ARGSUSED*/
237 int
238 dsrtc_read(dev_t dev, struct uio *uio, int flags)
239 {
240 	struct dsrtc_softc *sc;
241 	int error;
242 
243 	if ((sc = device_lookup_private(&dsrtc_cd, minor(dev))) == NULL)
244 		return ENXIO;
245 
246 	const struct dsrtc_model * const dm = &sc->sc_model;
247 	if (uio->uio_offset >= dm->dm_nvram_size)
248 		return EINVAL;
249 
250 	if ((error = iic_acquire_bus(sc->sc_tag, 0)) != 0)
251 		return error;
252 
253 	KASSERT(uio->uio_offset >= 0);
254 	while (uio->uio_resid && uio->uio_offset < dm->dm_nvram_size) {
255 		uint8_t ch, cmd;
256 		const u_int a = uio->uio_offset;
257 		cmd = a + dm->dm_nvram_start;
258 		if ((error = iic_exec(sc->sc_tag,
259 		    uio->uio_resid > 1 ? I2C_OP_READ : I2C_OP_READ_WITH_STOP,
260 		    sc->sc_address, &cmd, 1, &ch, 1, 0)) != 0) {
261 			iic_release_bus(sc->sc_tag, 0);
262 			aprint_error_dev(sc->sc_dev,
263 			    "%s: read failed at 0x%x: %d\n",
264 			    __func__, a, error);
265 			return error;
266 		}
267 		if ((error = uiomove(&ch, 1, uio)) != 0) {
268 			iic_release_bus(sc->sc_tag, 0);
269 			return error;
270 		}
271 	}
272 
273 	iic_release_bus(sc->sc_tag, 0);
274 
275 	return 0;
276 }
277 
278 /*ARGSUSED*/
279 int
280 dsrtc_write(dev_t dev, struct uio *uio, int flags)
281 {
282 	struct dsrtc_softc *sc;
283 	int error;
284 
285 	if ((sc = device_lookup_private(&dsrtc_cd, minor(dev))) == NULL)
286 		return ENXIO;
287 
288 	const struct dsrtc_model * const dm = &sc->sc_model;
289 	if (uio->uio_offset >= dm->dm_nvram_size)
290 		return EINVAL;
291 
292 	if ((error = iic_acquire_bus(sc->sc_tag, 0)) != 0)
293 		return error;
294 
295 	while (uio->uio_resid && uio->uio_offset < dm->dm_nvram_size) {
296 		uint8_t cmdbuf[2];
297 		const u_int a = (int)uio->uio_offset;
298 		cmdbuf[0] = a + dm->dm_nvram_start;
299 		if ((error = uiomove(&cmdbuf[1], 1, uio)) != 0)
300 			break;
301 
302 		if ((error = iic_exec(sc->sc_tag,
303 		    uio->uio_resid ? I2C_OP_WRITE : I2C_OP_WRITE_WITH_STOP,
304 		    sc->sc_address, cmdbuf, 1, &cmdbuf[1], 1, 0)) != 0) {
305 			aprint_error_dev(sc->sc_dev,
306 			    "%s: write failed at 0x%x: %d\n",
307 			    __func__, a, error);
308 			break;
309 		}
310 	}
311 
312 	iic_release_bus(sc->sc_tag, 0);
313 
314 	return error;
315 }
316 
317 static int
318 dsrtc_gettime_ymdhms(struct todr_chip_handle *ch, struct clock_ymdhms *dt)
319 {
320 	struct dsrtc_softc *sc = ch->cookie;
321 	struct clock_ymdhms check;
322 	int retries;
323 
324 	memset(dt, 0, sizeof(*dt));
325 	memset(&check, 0, sizeof(check));
326 
327 	/*
328 	 * Since we don't support Burst Read, we have to read the clock twice
329 	 * until we get two consecutive identical results.
330 	 */
331 	retries = 5;
332 	do {
333 		dsrtc_clock_read_ymdhms(sc, dt);
334 		dsrtc_clock_read_ymdhms(sc, &check);
335 	} while (memcmp(dt, &check, sizeof(check)) != 0 && --retries);
336 
337 	return 0;
338 }
339 
340 static int
341 dsrtc_settime_ymdhms(struct todr_chip_handle *ch, struct clock_ymdhms *dt)
342 {
343 	struct dsrtc_softc *sc = ch->cookie;
344 
345 	if (dsrtc_clock_write_ymdhms(sc, dt) == 0)
346 		return -1;
347 
348 	return 0;
349 }
350 
351 static int
352 dsrtc_clock_read_ymdhms(struct dsrtc_softc *sc, struct clock_ymdhms *dt)
353 {
354 	struct dsrtc_model * const dm = &sc->sc_model;
355 	uint8_t bcd[DSXXXX_RTC_SIZE], cmdbuf[1];
356 	int error;
357 
358 	KASSERT(DSXXXX_RTC_SIZE >= dm->dm_rtc_size);
359 
360 	if ((error = iic_acquire_bus(sc->sc_tag, I2C_F_POLL)) != 0) {
361 		aprint_error_dev(sc->sc_dev,
362 		    "%s: failed to acquire I2C bus: %d\n",
363 		    __func__, error);
364 		return 0;
365 	}
366 
367 	/* Read each RTC register in order. */
368 	for (u_int i = 0; !error && i < dm->dm_rtc_size; i++) {
369 		cmdbuf[0] = dm->dm_rtc_start + i;
370 
371 		error = iic_exec(sc->sc_tag, I2C_OP_READ_WITH_STOP,
372 		    sc->sc_address, cmdbuf, 1, &bcd[i], 1, I2C_F_POLL);
373 	}
374 
375 	/* Done with I2C */
376 	iic_release_bus(sc->sc_tag, I2C_F_POLL);
377 
378 	if (error != 0) {
379 		aprint_error_dev(sc->sc_dev,
380 		    "%s: failed to read rtc at 0x%x: %d\n",
381 		    __func__, cmdbuf[0], error);
382 		return 0;
383 	}
384 
385 	/*
386 	 * Convert the RTC's register values into something useable
387 	 */
388 	dt->dt_sec = FROMBCD(bcd[DSXXXX_SECONDS] & DSXXXX_SECONDS_MASK);
389 	dt->dt_min = FROMBCD(bcd[DSXXXX_MINUTES] & DSXXXX_MINUTES_MASK);
390 
391 	if ((bcd[DSXXXX_HOURS] & DSXXXX_HOURS_12HRS_MODE) != 0) {
392 		dt->dt_hour = FROMBCD(bcd[DSXXXX_HOURS] &
393 		    DSXXXX_HOURS_12MASK) % 12; /* 12AM -> 0, 12PM -> 12 */
394 		if (bcd[DSXXXX_HOURS] & DSXXXX_HOURS_12HRS_PM)
395 			dt->dt_hour += 12;
396 	} else
397 		dt->dt_hour = FROMBCD(bcd[DSXXXX_HOURS] &
398 		    DSXXXX_HOURS_24MASK);
399 
400 	dt->dt_day = FROMBCD(bcd[DSXXXX_DATE] & DSXXXX_DATE_MASK);
401 	dt->dt_mon = FROMBCD(bcd[DSXXXX_MONTH] & DSXXXX_MONTH_MASK);
402 
403 	/* XXX: Should be an MD way to specify EPOCH used by BIOS/Firmware */
404 	dt->dt_year = FROMBCD(bcd[DSXXXX_YEAR]) + POSIX_BASE_YEAR;
405 	if (bcd[DSXXXX_MONTH] & DSXXXX_MONTH_CENTURY)
406 		dt->dt_year += 100;
407 
408 	return 1;
409 }
410 
411 static int
412 dsrtc_clock_write_ymdhms(struct dsrtc_softc *sc, struct clock_ymdhms *dt)
413 {
414 	struct dsrtc_model * const dm = &sc->sc_model;
415 	uint8_t bcd[DSXXXX_RTC_SIZE], cmdbuf[2];
416 	int error;
417 
418 	KASSERT(DSXXXX_RTC_SIZE >= dm->dm_rtc_size);
419 
420 	/*
421 	 * Convert our time representation into something the DSXXXX
422 	 * can understand.
423 	 */
424 	bcd[DSXXXX_SECONDS] = TOBCD(dt->dt_sec);
425 	bcd[DSXXXX_MINUTES] = TOBCD(dt->dt_min);
426 	bcd[DSXXXX_HOURS] = TOBCD(dt->dt_hour); /* DSXXXX_HOURS_12HRS_MODE=0 */
427 	bcd[DSXXXX_DATE] = TOBCD(dt->dt_day);
428 	bcd[DSXXXX_DAY] = TOBCD(dt->dt_wday);
429 	bcd[DSXXXX_MONTH] = TOBCD(dt->dt_mon);
430 	bcd[DSXXXX_YEAR] = TOBCD((dt->dt_year - POSIX_BASE_YEAR) % 100);
431 	if (dt->dt_year - POSIX_BASE_YEAR >= 100)
432 		bcd[DSXXXX_MONTH] |= DSXXXX_MONTH_CENTURY;
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 	/* Stop the clock */
442 	cmdbuf[0] = dm->dm_ch_reg;
443 
444 	if ((error = iic_exec(sc->sc_tag, I2C_OP_READ, sc->sc_address,
445 	    cmdbuf, 1, &cmdbuf[1], 1, I2C_F_POLL)) != 0) {
446 		iic_release_bus(sc->sc_tag, I2C_F_POLL);
447 		aprint_error_dev(sc->sc_dev,
448 		    "%s: failed to read Hold Clock: %d\n",
449 		    __func__, error);
450 		return 0;
451 	}
452 
453 	cmdbuf[1] |= dm->dm_ch_value;
454 
455 	if ((error = iic_exec(sc->sc_tag, I2C_OP_WRITE, sc->sc_address,
456 	    cmdbuf, 1, &cmdbuf[1], 1, I2C_F_POLL)) != 0) {
457 		iic_release_bus(sc->sc_tag, I2C_F_POLL);
458 		aprint_error_dev(sc->sc_dev,
459 		    "%s: failed to write Hold Clock: %d\n",
460 		    __func__, error);
461 		return 0;
462 	}
463 
464 	/*
465 	 * Write registers in reverse order. The last write (to the Seconds
466 	 * register) will undo the Clock Hold, above.
467 	 */
468 	uint8_t op = I2C_OP_WRITE;
469 	for (signed int i = dm->dm_rtc_size - 1; i >= 0; i--) {
470 		cmdbuf[0] = dm->dm_rtc_start + i;
471 		if (dm->dm_rtc_start + i == dm->dm_ch_reg) {
472 			op = I2C_OP_WRITE_WITH_STOP;
473 		}
474 		if ((error = iic_exec(sc->sc_tag, op, sc->sc_address,
475 		    cmdbuf, 1, &bcd[i], 1, I2C_F_POLL)) != 0) {
476 			iic_release_bus(sc->sc_tag, I2C_F_POLL);
477 			aprint_error_dev(sc->sc_dev,
478 			    "%s: failed to write rtc at 0x%x: %d\n",
479 			    __func__, i, error);
480 			/* XXX: Clock Hold is likely still asserted! */
481 			return 0;
482 		}
483 	}
484 	/*
485 	 * If the clock hold register isn't the same register as seconds,
486 	 * we need to reeanble the clock.
487 	 */
488 	if (op != I2C_OP_WRITE_WITH_STOP) {
489 		cmdbuf[0] = dm->dm_ch_reg;
490 		cmdbuf[1] &= ~dm->dm_ch_value;
491 
492 		if ((error = iic_exec(sc->sc_tag, I2C_OP_WRITE_WITH_STOP,
493 		    sc->sc_address, cmdbuf, 1, &cmdbuf[1], 1,
494 		    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 Hold Clock: %d\n",
498 			    __func__, error);
499 			return 0;
500 		}
501 	}
502 
503 	iic_release_bus(sc->sc_tag, I2C_F_POLL);
504 
505 	return 1;
506 }
507 
508 static int
509 dsrtc_gettime_timeval(struct todr_chip_handle *ch, struct timeval *tv)
510 {
511 	struct dsrtc_softc *sc = ch->cookie;
512 	struct timeval check;
513 	int retries;
514 
515 	memset(tv, 0, sizeof(*tv));
516 	memset(&check, 0, sizeof(check));
517 
518 	/*
519 	 * Since we don't support Burst Read, we have to read the clock twice
520 	 * until we get two consecutive identical results.
521 	 */
522 	retries = 5;
523 	do {
524 		dsrtc_clock_read_timeval(sc, &tv->tv_sec);
525 		dsrtc_clock_read_timeval(sc, &check.tv_sec);
526 	} while (memcmp(tv, &check, sizeof(check)) != 0 && --retries);
527 
528 	return 0;
529 }
530 
531 static int
532 dsrtc_settime_timeval(struct todr_chip_handle *ch, struct timeval *tv)
533 {
534 	struct dsrtc_softc *sc = ch->cookie;
535 
536 	if (dsrtc_clock_write_timeval(sc, tv->tv_sec) == 0)
537 		return -1;
538 
539 	return 0;
540 }
541 
542 /*
543  * The RTC probably has a nice Clock Burst Read/Write command, but we can't use
544  * it, since some I2C controllers don't support anything other than single-byte
545  * transfers.
546  */
547 static int
548 dsrtc_clock_read_timeval(struct dsrtc_softc *sc, time_t *tp)
549 {
550 	const struct dsrtc_model * const dm = &sc->sc_model;
551 	uint8_t buf[4];
552 	int error;
553 
554 	if ((error = iic_acquire_bus(sc->sc_tag, I2C_F_POLL)) != 0) {
555 		aprint_error_dev(sc->sc_dev,
556 		    "%s: failed to acquire I2C bus: %d\n",
557 		    __func__, error);
558 		return 0;
559 	}
560 
561 	/* read all registers: */
562 	uint8_t reg = dm->dm_rtc_start;
563 	error = iic_exec(sc->sc_tag, I2C_OP_READ_WITH_STOP, sc->sc_address,
564 	     &reg, 1, buf, 4, I2C_F_POLL);
565 
566 	/* Done with I2C */
567 	iic_release_bus(sc->sc_tag, I2C_F_POLL);
568 
569 	if (error != 0) {
570 		aprint_error_dev(sc->sc_dev,
571 		    "%s: failed to read rtc at 0x%x: %d\n",
572 		    __func__, reg, error);
573 		return 0;
574 	}
575 
576 	uint32_t v = (buf[3] << 24) | (buf[2] << 16) | (buf[1] << 8) | buf[0];
577 	*tp = v;
578 
579 	aprint_debug_dev(sc->sc_dev, "%s: cntr=0x%08"PRIx32"\n",
580 	    __func__, v);
581 
582 	return 1;
583 }
584 
585 static int
586 dsrtc_clock_write_timeval(struct dsrtc_softc *sc, time_t t)
587 {
588 	const struct dsrtc_model * const dm = &sc->sc_model;
589 	size_t buflen = dm->dm_rtc_size + 2;
590 	uint8_t buf[buflen];
591 	int error;
592 
593 	KASSERT((dm->dm_flags & DSRTC_FLAG_CLOCK_HOLD) == 0);
594 	KASSERT(dm->dm_ch_reg == dm->dm_rtc_start + 4);
595 
596 	buf[0] = dm->dm_rtc_start;
597 	buf[1] = (t >> 0) & 0xff;
598 	buf[2] = (t >> 8) & 0xff;
599 	buf[3] = (t >> 16) & 0xff;
600 	buf[4] = (t >> 24) & 0xff;
601 	buf[5] = 0;
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 	error = iic_exec(sc->sc_tag, I2C_OP_WRITE_WITH_STOP, sc->sc_address,
611 	    &buf, buflen, NULL, 0, I2C_F_POLL);
612 
613 	/* Done with I2C */
614 	iic_release_bus(sc->sc_tag, I2C_F_POLL);
615 
616 	/* send data */
617 	if (error != 0) {
618 		aprint_error_dev(sc->sc_dev,
619 		    "%s: failed to set time: %d\n",
620 		    __func__, error);
621 		return 0;
622 	}
623 
624 	return 1;
625 }
626