xref: /netbsd-src/sys/dev/i2c/adm1026.c (revision f3cfa6f6ce31685c6c4a758bc430e69eb99f50a4)
1 /*-
2  * Copyright (c) 2015 The NetBSD Foundation, Inc.
3  * All rights reserved.
4  *
5  * This code is derived from software contributed to The NetBSD Foundation
6  * by Julian Coleman.
7  *
8  * Redistribution and use in source and binary forms, with or without
9  * modification, are permitted provided that the following conditions
10  * are met:
11  * 1. Redistributions of source code must retain the above copyright
12  *    notice, this list of conditions and the following disclaimer.
13  * 2. Redistributions in binary form must reproduce the above copyright
14  *    notice, this list of conditions and the following disclaimer in the
15  *    documentation and/or other materials provided with the distribution.
16  *
17  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
18  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
19  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
20  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
21  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
22  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
23  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
24  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
25  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
26  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
27  * POSSIBILITY OF SUCH DAMAGE.
28  */
29 
30 #include <sys/cdefs.h>
31 __KERNEL_RCSID(0, "$NetBSD: adm1026.c,v 1.5 2018/06/26 06:03:57 thorpej Exp $");
32 
33 #include <sys/param.h>
34 #include <sys/systm.h>
35 #include <sys/device.h>
36 #include <sys/kernel.h>
37 #include <sys/sysctl.h>
38 
39 #include <dev/sysmon/sysmonvar.h>
40 
41 #include <dev/i2c/i2cvar.h>
42 #include <dev/i2c/adm1026reg.h>
43 
44 /* Voltage/analog sensors descriptions and registers */
45 struct adm1026_volts_info {
46 	const char* desc;
47 	int incr;
48 	uint8_t reg, check_tdm2;
49 };
50 
51 /* Voltage maximums (in mV) from datasheet table 7 divided by 255 increments */
52 static struct adm1026_volts_info adm1026_volts_table[] = {
53 	{ "Vbatt", 15624, ADM1026_VBAT_VAL, 0 },
54 	{ "V3.3 standby", 17345, ADM1026_33VSTBY_VAL, 0 },
55 	{ "V3.3 main", 17345, ADM1026_33VMAIN_VAL, 0 },
56 	{ "V5.0", 26016, ADM1026_50V_VAL, 0 },
57 	{ "Vccp", 11718, ADM1026_VCCP_VAL, 0 },
58 	{ "V+12", 62502, ADM1026_12V_VAL, 0 },
59 	{ "V-12", -62502, ADM1026_N12V_VAL, 0 },
60 	{ "V3.0 0", 11718, ADM1026_AIN_VAL(0), 0 },
61 	{ "V3.0 1", 11718, ADM1026_AIN_VAL(1), 0 },
62 	{ "V3.0 2", 11718, ADM1026_AIN_VAL(2), 0 },
63 	{ "V3.0 3", 11718, ADM1026_AIN_VAL(3), 0 },
64 	{ "V3.0 4", 11718, ADM1026_AIN_VAL(4), 0 },
65 	{ "V3.0 5", 11718, ADM1026_AIN_VAL(5), 0 },
66 	{ "V2.5 0", 9765, ADM1026_AIN_VAL(6), 0 },
67 	{ "V2.5 1", 9765, ADM1026_AIN_VAL(7), 0 },
68 	{ "V2.5 2", 9765, ADM1026_AIN8_VAL, 1 },
69 	{ "V2.5 3", 9765, ADM1026_TDM2_AIN9_VAL, 1 }
70 };
71 
72 /* Maximum number of each type of sensor */
73 #define ADM1026_MAX_FANS	8
74 #define ADM1026_MAX_TEMPS	3
75 #define ADM1026_MAX_VOLTS	(sizeof(adm1026_volts_table) / \
76 				    sizeof (adm1026_volts_table[0]))
77 
78 /* Map sensor to/from sysmon numbers */
79 #define ADM1026_FAN_NUM(x)	(x)
80 #define ADM1026_TEMP_NUM(x)	(x + sc->sc_nfans)
81 #define ADM1026_VOLT_NUM(x)	(x + sc->sc_nfans + sc->sc_ntemps)
82 #define ADM1026_NUM_FAN(x)	(x)
83 #define ADM1026_NUM_TEMP(x)	(x - sc->sc_nfans)
84 #define ADM1026_NUM_VOLT(x)	(x - sc->sc_nfans - sc->sc_ntemps)
85 
86 struct adm1026_softc {
87 	device_t sc_dev;
88 	i2c_tag_t sc_tag;
89 	int sc_address;
90 	int sc_iic_flags;
91 	bool sc_multi_read;
92 
93 	uint8_t sc_rev, sc_cfg[2];
94 	int sc_nfans, sc_ntemps;	/* Map sysmon numbers to sensors */
95 	int sc_fandiv[ADM1026_MAX_FANS], sc_temp_off[ADM1026_MAX_TEMPS];
96 	struct sysmon_envsys *sc_sme;
97 	envsys_data_t sc_sensor[ADM1026_MAX_FANS + ADM1026_MAX_TEMPS +
98 	    ADM1026_MAX_VOLTS];
99 };
100 
101 static int adm1026_match(device_t, cfdata_t, void *);
102 static int adm1026_ident(struct adm1026_softc *sc);
103 static void adm1026_attach(device_t, device_t, void *);
104 static int adm1026_detach(device_t, int);
105 bool adm1026_pmf_suspend(device_t dev, const pmf_qual_t *qual);
106 bool adm1026_pmf_resume(device_t dev, const pmf_qual_t *qual);
107 
108 static void adm1026_setup_fans(struct adm1026_softc *sc, int div2_val);
109 static void adm1026_setup_temps(struct adm1026_softc *sc);
110 static void adm1026_setup_volts(struct adm1026_softc *sc);
111 
112 void adm1026_refresh(struct sysmon_envsys *sme, envsys_data_t *edata);
113 static void adm1026_read_fan(struct adm1026_softc *sc, envsys_data_t *edata);
114 static void adm1026_read_temp(struct adm1026_softc *sc, envsys_data_t *edata);
115 static void adm1026_read_volt(struct adm1026_softc *sc, envsys_data_t *edata);
116 
117 static int adm1026_read_reg(struct adm1026_softc *sc,
118     uint8_t reg, uint8_t *val);
119 static int adm1026_write_reg(struct adm1026_softc *sc,
120     uint8_t reg, uint8_t val);
121 
122 CFATTACH_DECL_NEW(adm1026hm, sizeof(struct adm1026_softc),
123 	adm1026_match, adm1026_attach, adm1026_detach, NULL);
124 
125 static const struct device_compatible_entry compat_data[] = {
126 	{ "i2c-adm1026",		0 },
127 	{ NULL,				0 }
128 };
129 
130 static int
131 adm1026_match(device_t parent, cfdata_t cf, void *aux)
132 {
133 	struct i2c_attach_args *ia = aux;
134 	struct adm1026_softc sc;	/* For chip ident */
135 	int match_result;
136 
137 	sc.sc_tag = ia->ia_tag;
138 	sc.sc_address = ia->ia_addr;
139 	sc.sc_iic_flags = 0;
140 
141 	if (iic_use_direct_match(ia, cf, compat_data, &match_result))
142 		return match_result;
143 
144 	if ((ia->ia_addr & ADM1026_ADDRMASK) == ADM1026_ADDR &&
145 	    adm1026_ident(&sc))
146 		return I2C_MATCH_ADDRESS_AND_PROBE;
147 
148 	return 0;
149 }
150 
151 static int
152 adm1026_ident(struct adm1026_softc *sc)
153 {
154 	uint8_t val;
155 	int err;
156 
157 	/* Manufacturer ID and revision/stepping */
158 	err = adm1026_read_reg(sc, ADM1026_ID, &val);
159 	if (err || val != ADM1026_MANF_ID) {
160 		aprint_verbose("adm1026_ident: "
161 		    "manufacturer ID invalid or missing\n");
162 		return 0;
163 	}
164 	err = adm1026_read_reg(sc, ADM1026_REV, &sc->sc_rev);
165 	if (err || ADM1026_REVISION(sc->sc_rev) != ADM1026_MANF_REV) {
166 		aprint_verbose("adm1026_ident: "
167 		    "manufacturer revision invalid or missing\n");
168 		return 0;
169 	}
170 	return 1;
171 }
172 
173 static void
174 adm1026_attach(device_t parent, device_t self, void *aux)
175 {
176 	struct adm1026_softc *sc = device_private(self);
177 	struct i2c_attach_args *ia = aux;
178 	prop_dictionary_t props = device_properties(self);
179 	uint8_t val, fan_div2;
180 	int err, div2_val;
181 
182 	sc->sc_tag = ia->ia_tag;
183 	sc->sc_address = ia->ia_addr;
184 	sc->sc_dev = self;
185 	sc->sc_iic_flags = I2C_F_POLL;	/* Use polling during autoconf */
186 
187 	sc->sc_multi_read = false;
188 	prop_dictionary_get_bool(props, "multi_read", &sc->sc_multi_read);
189 	if (prop_dictionary_get_uint8(props, "fan_div2", &fan_div2) != 0)
190 		div2_val = fan_div2;
191 	else
192 		div2_val = -1;
193 
194 	(void) adm1026_ident(sc);
195 	aprint_normal(": ADM1026 hardware monitor: rev. 0x%x, step. 0x%x\n",
196 	    ADM1026_REVISION(sc->sc_rev), ADM1026_STEPPING(sc->sc_rev));
197 
198 	/*
199 	 * Start monitoring if not already monitoring.
200 	 * Wait 1.8s for the fan readings to stabilise.
201 	 */
202 	if ((err = adm1026_read_reg(sc, ADM1026_CONF1, &val)) != 0) {
203 		aprint_error_dev(sc->sc_dev, ": unable to read conf1\n");
204 		return;
205 	}
206 	if (!(val & ADM1026_CONF1_MONITOR)) {
207 		aprint_normal_dev(sc->sc_dev,
208 		    ": starting monitoring, waiting 1.8s for readings\n");
209 		val |= ADM1026_CONF1_MONITOR;
210 		if ((err = adm1026_write_reg(sc, ADM1026_CONF1, val)) != 0) {
211 			aprint_error_dev(sc->sc_dev,
212 			    ": unable to write conf1\n");
213 			return;
214 		}
215 		delay(1800000);
216 	}
217 	sc->sc_cfg[0] = val;
218 
219 	sc->sc_sme = sysmon_envsys_create();
220 	sc->sc_nfans = 0;
221 	adm1026_setup_fans(sc, div2_val);
222 	sc->sc_ntemps = 0;
223 	adm1026_setup_temps(sc);
224 	adm1026_setup_volts(sc);
225 	aprint_normal_dev(self, "%d fans, %d temperatures, %d voltages\n",
226 	    sc->sc_nfans, sc->sc_ntemps, sc->sc_ntemps == 3 ? 15 : 17);
227 
228         sc->sc_sme->sme_name = device_xname(self);
229         sc->sc_sme->sme_cookie = sc;
230         sc->sc_sme->sme_refresh = adm1026_refresh;
231 	if (sysmon_envsys_register(sc->sc_sme)) {
232 		aprint_error_dev(self,
233 		    "unable to register with sysmon\n");
234 		sysmon_envsys_destroy(sc->sc_sme);
235 		return;
236 	}
237 
238 	if (!pmf_device_register(self, adm1026_pmf_suspend, adm1026_pmf_resume))
239 		aprint_error_dev(self, "couldn't establish power handler\n");
240 
241 	sc->sc_iic_flags = 0;	/* Drop polling flag */
242 
243 	return;
244 }
245 
246 /*
247  * We could stop (suspend/detach) and restart (resume) monitoring,
248  * but we don't do that because some machines have separate
249  * management hardware which can read the sensors.
250  */
251 bool
252 adm1026_pmf_suspend(device_t dev, const pmf_qual_t *qual)
253 {
254 	return true;
255 }
256 
257 bool
258 adm1026_pmf_resume(device_t dev, const pmf_qual_t *qual)
259 {
260 	return true;
261 }
262 
263 static int
264 adm1026_detach(device_t self, int flags)
265 {
266 	struct adm1026_softc *sc = device_private(self);
267 
268 	pmf_device_deregister(self);
269 
270 	sysmon_envsys_unregister(sc->sc_sme);
271 	sc->sc_sme = NULL;
272 
273 	return 0;
274 }
275 
276 static void
277 adm1026_setup_fans(struct adm1026_softc *sc, int div2_val)
278 {
279 	int i, err = 0;
280 	uint8_t div1, div2;
281 
282 	/* Read fan-related registers (configuration and divisors) */
283 	if ((err = adm1026_read_reg(sc, ADM1026_CONF2, &sc->sc_cfg[1])) != 0) {
284 		aprint_error_dev(sc->sc_dev, "unable to read conf2\n");
285 		return;
286 	}
287 	if ((err = adm1026_read_reg(sc, ADM1026_FAN_DIV1, &div1)) != 0) {
288 		aprint_error_dev(sc->sc_dev, "unable to read fan_div1\n");
289 		return;
290 	}
291 	sc->sc_fandiv[0] = 1 << ADM1026_FAN0_DIV(div1);
292 	sc->sc_fandiv[1] = 1 << ADM1026_FAN1_DIV(div1);
293 	sc->sc_fandiv[2] = 1 << ADM1026_FAN2_DIV(div1);
294 	sc->sc_fandiv[3] = 1 << ADM1026_FAN3_DIV(div1);
295 	if (div2_val < 0) {
296 		if ((err =
297 		    adm1026_read_reg(sc, ADM1026_FAN_DIV2, &div2)) != 0) {
298 			aprint_error_dev(sc->sc_dev,
299 			    "unable to read fan_div2\n");
300 			return;
301 		}
302 	} else
303 		div2 = div2_val;
304 	sc->sc_fandiv[4] = 1 << ADM1026_FAN4_DIV(div2);
305 	sc->sc_fandiv[5] = 1 << ADM1026_FAN5_DIV(div2);
306 	sc->sc_fandiv[6] = 1 << ADM1026_FAN6_DIV(div2);
307 	sc->sc_fandiv[7] = 1 << ADM1026_FAN7_DIV(div2);
308 
309 	for (i = 0; i < ADM1026_MAX_FANS; i++) {
310 		sc->sc_sensor[ADM1026_FAN_NUM(i)].state = ENVSYS_SINVALID;
311 		/* Check configuration2 register to see which pins are fans. */
312 		if (ADM1026_PIN_IS_FAN(sc->sc_cfg[1], i)) {
313 			sc->sc_sensor[ADM1026_FAN_NUM(i)].units =
314 			    ENVSYS_SFANRPM;
315 			snprintf(sc->sc_sensor[ADM1026_FAN_NUM(i)].desc,
316 			    sizeof(sc->sc_sensor[ADM1026_FAN_NUM(i)].desc),
317 			    "fan %d", ADM1026_FAN_NUM(i));
318 			sc->sc_nfans++;
319 			if (sysmon_envsys_sensor_attach(
320 			    sc->sc_sme, &sc->sc_sensor[ADM1026_FAN_NUM(i)])) {
321 				sysmon_envsys_destroy(sc->sc_sme);
322 				aprint_error_dev(sc->sc_dev,
323 				    "unable to attach fan %d at sysmon\n", i);
324 				return;
325 			}
326 		}
327 	}
328 }
329 
330 static void
331 adm1026_setup_temps(struct adm1026_softc *sc)
332 {
333 	int i;
334 	uint8_t val;
335 
336 	/* Temperature offsets */
337 	if (adm1026_read_reg(sc, ADM1026_INT_TEMP_OFF, &val)
338 	    != 0) {
339 		aprint_error_dev(sc->sc_dev, "unable to read int temp. off.\n");
340 		return;
341 	}
342 	if (val & 0x80)
343 		sc->sc_temp_off[0] = 0 - 1000000 * (val & 0x7f);
344 	else
345 		sc->sc_temp_off[0] = 1000000 * (val & 0x7f);
346 	if (adm1026_read_reg(sc, ADM1026_TDM1_OFF, &val) != 0) {
347 		aprint_error_dev(sc->sc_dev, "unable to read tdm1 off.\n");
348 		return;
349 	}
350 	if (val & 0x80)
351 		sc->sc_temp_off[1] = 0 - 1000000 * (val & 0x7f);
352 	else
353 		sc->sc_temp_off[1] = 1000000 * (val & 0x7f);
354 	if (adm1026_read_reg(sc, ADM1026_TDM2_OFF, &val) != 0) {
355 		aprint_error_dev(sc->sc_dev, "unable to read tdm2 off.\n");
356 		return;
357 	}
358 	if (val & 0x80)
359 		sc->sc_temp_off[2] = 0 - 1000000 * (val & 0x7f);
360 	else
361 		sc->sc_temp_off[2] = 1000000 * (val & 0x7f);
362 
363 	strlcpy(sc->sc_sensor[ADM1026_TEMP_NUM(0)].desc, "internal",
364 	    sizeof(sc->sc_sensor[ADM1026_TEMP_NUM(0)].desc));
365 	strlcpy(sc->sc_sensor[ADM1026_TEMP_NUM(1)].desc, "external 1",
366 	    sizeof(sc->sc_sensor[ADM1026_TEMP_NUM(1)].desc));
367 	strlcpy(sc->sc_sensor[ADM1026_TEMP_NUM(2)].desc, "external 2",
368 	    sizeof(sc->sc_sensor[ADM1026_TEMP_NUM(2)].desc));
369 	for (i = 0; i < ADM1026_MAX_TEMPS; i++) {
370 		/* Check configuration1 register to see if TDM2 is configured */
371 		if (i == 2 && !ADM1026_PIN_IS_TDM2(sc->sc_cfg[0]))
372 			continue;
373 		sc->sc_sensor[ADM1026_TEMP_NUM(i)].units = ENVSYS_STEMP;
374 		sc->sc_sensor[ADM1026_TEMP_NUM(i)].state = ENVSYS_SINVALID;
375 		sc->sc_ntemps++;
376 		if (sysmon_envsys_sensor_attach(
377 		    sc->sc_sme, &sc->sc_sensor[ADM1026_TEMP_NUM(i)])) {
378 			sysmon_envsys_destroy(sc->sc_sme);
379 			aprint_error_dev(sc->sc_dev,
380 			    "unable to attach temp %d at sysmon\n", i);
381 			return;
382 		}
383 	}
384 }
385 
386 static void
387 adm1026_setup_volts(struct adm1026_softc *sc)
388 {
389 	int i;
390 
391 	for (i = 0; i < ADM1026_MAX_VOLTS; i++) {
392 		/* Check configuration1 register to see if TDM2 is configured */
393 		if (adm1026_volts_table[i].check_tdm2 &&
394 		    ADM1026_PIN_IS_TDM2(sc->sc_cfg[0]))
395 			continue;
396 		strlcpy(sc->sc_sensor[ADM1026_VOLT_NUM(i)].desc,
397 		    adm1026_volts_table[i].desc,
398 		    sizeof(sc->sc_sensor[ADM1026_VOLT_NUM(i)].desc));
399 		sc->sc_sensor[ADM1026_VOLT_NUM(i)].units = ENVSYS_SVOLTS_DC;
400 		sc->sc_sensor[ADM1026_VOLT_NUM(i)].state = ENVSYS_SINVALID;
401 		if (sysmon_envsys_sensor_attach(
402 		    sc->sc_sme, &sc->sc_sensor[ADM1026_VOLT_NUM(i)])) {
403 			sysmon_envsys_destroy(sc->sc_sme);
404 			aprint_error_dev(sc->sc_dev,
405 			    "unable to attach volts %d at sysmon\n", i);
406 			return;
407 		}
408 	}
409 }
410 
411 void
412 adm1026_refresh(struct sysmon_envsys *sme, envsys_data_t *edata)
413 {
414 	struct adm1026_softc *sc = sme->sme_cookie;
415 
416 	if (edata->sensor < sc->sc_nfans)
417 		adm1026_read_fan(sc, edata);
418 	else if (edata->sensor < sc->sc_nfans + sc->sc_ntemps)
419 		adm1026_read_temp(sc, edata);
420 	else
421 		adm1026_read_volt(sc, edata);
422 }
423 
424 static void
425 adm1026_read_fan(struct adm1026_softc *sc, envsys_data_t *edata)
426 {
427 	int fan = ADM1026_NUM_FAN(edata->sensor);
428 	int err;
429 	uint8_t	val;
430 
431 	if ((err = adm1026_read_reg(sc, ADM1026_FAN_VAL(fan), &val)) != 0) {
432 		edata->state = ENVSYS_SINVALID;
433 		return;
434 	}
435 	if (val == 0xff || val == 0x00)	/* Fan missing or stopped */
436 		edata->value_cur = 0;
437 	else
438 		edata->value_cur = 1350000 / (val * sc->sc_fandiv[fan]);
439 	edata->state = ENVSYS_SVALID;
440 }
441 
442 static void
443 adm1026_read_temp(struct adm1026_softc *sc, envsys_data_t *edata)
444 {
445 	int temp = ADM1026_NUM_TEMP(edata->sensor);
446 	int err;
447 	uint8_t	val;
448 
449 	if (temp == 0)
450 		err = adm1026_read_reg(sc, ADM1026_INT_TEMP_VAL, &val);
451 	else if (temp == 1)
452 		err = adm1026_read_reg(sc, ADM1026_TDM1_VAL, &val);
453 	else
454 		err = adm1026_read_reg(sc, ADM1026_TDM2_AIN9_VAL, &val);
455 	if (err) {
456 		edata->state = ENVSYS_SINVALID;
457 		return;
458 	}
459 
460 	if (val & 0x80)	/* Negative temperature */
461 		edata->value_cur = 273150000 - sc->sc_temp_off[temp] -
462 		    1000000 * (val & 0x7f);
463 	else		/* Positive temperature */
464 		edata->value_cur = 273150000 - sc->sc_temp_off[temp] +
465 		    1000000 * val;
466 	edata->state = ENVSYS_SVALID;
467 }
468 
469 static void
470 adm1026_read_volt(struct adm1026_softc *sc, envsys_data_t *edata)
471 {
472 	int volt = ADM1026_NUM_VOLT(edata->sensor);
473 	int err;
474 	uint8_t	val;
475 
476 	err = adm1026_read_reg(sc, adm1026_volts_table[volt].reg, &val);
477 	if (err) {
478 		edata->state = ENVSYS_SINVALID;
479 		return;
480 	}
481 	/* Vbatt is not valid for < 1.5V */
482 	if (volt == 0 && val < 0x60)
483 		edata->state = ENVSYS_SINVALID;
484 	edata->value_cur = (int) val * adm1026_volts_table[volt].incr;
485 	edata->state = ENVSYS_SVALID;
486 }
487 
488 static int
489 adm1026_read_reg(struct adm1026_softc *sc, uint8_t reg, uint8_t *val)
490 {
491 #define ADM1026_READ_RETRIES	5
492 	int i, j, err = 0;
493 	uint8_t creg, cval, tmp[ADM1026_READ_RETRIES + 1];
494 
495 	if ((err = iic_acquire_bus(sc->sc_tag, sc->sc_iic_flags)) != 0)
496 		return err;
497 	/* Standard ADM1026 */
498 	if (sc->sc_multi_read == false) {
499 		err = iic_exec(sc->sc_tag, I2C_OP_READ_WITH_STOP,
500 		    sc->sc_address, &reg, 1, val, 1, 0);
501 	/*
502 	 * The ADM1026 found in some Sun machines sometimes reads bogus values.
503 	 * We'll read at least twice and check that we get (nearly) the same
504 	 * value.  If not, we'll read another register and then re-read the
505 	 * first.
506 	 */
507 	} else {
508 		if (reg == ADM1026_CONF1)
509 			creg = ADM1026_CONF2;
510 		else
511 			creg = ADM1026_CONF1;
512 		if ((err = iic_exec(sc->sc_tag, I2C_OP_READ_WITH_STOP,
513 		    sc->sc_address, &reg, 1, &tmp[0], 1, 0)) != 0) {
514 			iic_release_bus(sc->sc_tag, sc->sc_iic_flags);
515 			return err;
516 		}
517 		for (i = 1; i <= ADM1026_READ_RETRIES; i++) {
518 			if ((err = iic_exec(sc->sc_tag, I2C_OP_READ_WITH_STOP,
519 			    sc->sc_address, &reg, 1, &tmp[i], 1, 0)) != 0)
520 				break;
521 			for (j = 0; j < i; j++)
522 				if (abs(tmp[j] - tmp[i]) < 3) {
523 					*val = tmp[i];
524 					iic_release_bus(sc->sc_tag,
525 					    sc->sc_iic_flags);
526 					return 0;
527 				}
528 			if ((err = iic_exec(sc->sc_tag, I2C_OP_READ_WITH_STOP,
529 			    sc->sc_address, &creg, 1, &cval, 1, 0)) != 0)
530 				break;
531 			err = -1;	/* Return error if we don't match. */
532 		}
533 	}
534 	iic_release_bus(sc->sc_tag, sc->sc_iic_flags);
535 	return err;
536 }
537 
538 static int
539 adm1026_write_reg(struct adm1026_softc *sc, uint8_t reg, uint8_t val)
540 {
541 	int err = 0;
542 
543 	if ((err = iic_acquire_bus(sc->sc_tag, sc->sc_iic_flags)) != 0)
544 		return err;
545 	err = iic_exec(sc->sc_tag, I2C_OP_WRITE_WITH_STOP, sc->sc_address,
546 	    &reg, 1, &val, 1, 0);
547 	iic_release_bus(sc->sc_tag, sc->sc_iic_flags);
548 	return err;
549 }
550