xref: /netbsd-src/sys/dev/i2c/lm75.c (revision 9e0de8ef629e4d0dbcceb4b58bcdd81472e17c66)
1 /*	$NetBSD: lm75.c,v 1.47 2025/01/02 18:40:54 skrll Exp $	*/
2 
3 /*
4  * Copyright (c) 2003 Wasabi Systems, Inc.
5  * All rights reserved.
6  *
7  * Written by 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: lm75.c,v 1.47 2025/01/02 18:40:54 skrll 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/sysctl.h>
46 
47 #include <dev/sysmon/sysmonvar.h>
48 
49 #include <dev/i2c/i2cvar.h>
50 #include <dev/i2c/lm75reg.h>
51 
52 struct lmtemp_softc {
53 	device_t sc_dev;
54 	i2c_tag_t sc_tag;
55 	int sc_address;
56 	prop_dictionary_t sc_prop;
57 
58 	struct sysmon_envsys *sc_sme;
59 	envsys_data_t sc_sensor;
60 	int sc_tmax;
61 	uint32_t sc_smax, sc_smin, sc_scrit;
62 
63 	uint32_t (*sc_lmtemp_decode)(const uint8_t *, int);
64 	void (*sc_lmtemp_encode)(const uint32_t, uint8_t *, int);
65 };
66 
67 static int  lmtemp_match(device_t, cfdata_t, void *);
68 static void lmtemp_attach(device_t, device_t, void *);
69 
70 CFATTACH_DECL_NEW(lmtemp, sizeof(struct lmtemp_softc),
71 	lmtemp_match, lmtemp_attach, NULL, NULL);
72 
73 static void	lmtemp_refresh(struct sysmon_envsys *, envsys_data_t *);
74 static int	lmtemp_config_write(struct lmtemp_softc *, uint8_t);
75 static int	lmtemp_temp_write(struct lmtemp_softc *, uint8_t, uint32_t,
76 				int);
77 static int	lmtemp_temp_read(struct lmtemp_softc *, uint8_t, uint32_t *,
78 				int);
79 static uint32_t lmtemp_decode_lm75(const uint8_t *, int);
80 static uint32_t lmtemp_decode_ds75(const uint8_t *, int);
81 static uint32_t lmtemp_decode_lm77(const uint8_t *, int);
82 static void	lmtemp_encode_lm75(const uint32_t, uint8_t *, int);
83 static void	lmtemp_encode_ds75(const uint32_t, uint8_t *, int);
84 static void	lmtemp_encode_lm77(const uint32_t, uint8_t *, int);
85 static void	lmtemp_getlim_lm75(struct sysmon_envsys *, envsys_data_t *,
86 				sysmon_envsys_lim_t *, uint32_t *);
87 static void	lmtemp_getlim_lm77(struct sysmon_envsys *, envsys_data_t *,
88 				sysmon_envsys_lim_t *, uint32_t *);
89 static void	lmtemp_setlim_lm75(struct sysmon_envsys *, envsys_data_t *,
90 				sysmon_envsys_lim_t *, uint32_t *);
91 static void	lmtemp_setlim_lm77(struct sysmon_envsys *, envsys_data_t *,
92 				sysmon_envsys_lim_t *, uint32_t *);
93 
94 static void	lmtemp_setup_sysctl(struct lmtemp_softc *);
95 static int	sysctl_lm75_temp(SYSCTLFN_ARGS);
96 
97 enum {
98 	lmtemp_lm75 = 0,
99 	lmtemp_ds75 = 1,
100 	lmtemp_lm77 = 2,
101 };
102 
103 static const struct device_compatible_entry compat_data[] = {
104 	{ .compat = "national,lm75",	.value = lmtemp_lm75 },
105 	{ .compat = "i2c-lm75",		.value = lmtemp_lm75 },
106 	{ .compat = "lm75",		.value = lmtemp_lm75 },
107 
108 	/* XXX Linux treats ds1775 and ds75 differently. */
109 	{ .compat = "dallas,ds1775",	.value = lmtemp_ds75 },
110 	{ .compat = "ds1775",		.value = lmtemp_ds75 },
111 
112 	{ .compat = "national,lm77",	.value = lmtemp_lm77 },
113 
114 	/*
115 	 * see XXX in _attach() below: add code once non-lm75 matches are
116 	 * added here!
117 	 */
118 	DEVICE_COMPAT_EOL
119 };
120 
121 static const struct {
122 	const char *lmtemp_name;
123 	int lmtemp_addrmask;
124 	int lmtemp_addr;
125 	uint32_t (*lmtemp_decode)(const uint8_t *, int);
126 	void (*lmtemp_encode)(const uint32_t, uint8_t *, int);
127 	void (*lmtemp_getlim)(struct sysmon_envsys *, envsys_data_t *,
128 		sysmon_envsys_lim_t *, uint32_t *);
129 	void (*lmtemp_setlim)(struct sysmon_envsys *, envsys_data_t *,
130 		sysmon_envsys_lim_t *, uint32_t *);
131 } lmtemptbl[] = {
132 [lmtemp_lm75] =
133 	{
134 		.lmtemp_name = "LM75",
135 		.lmtemp_addrmask = LM75_ADDRMASK,
136 		.lmtemp_addr = LM75_ADDR,
137 		.lmtemp_decode = lmtemp_decode_lm75,
138 		.lmtemp_encode = lmtemp_encode_lm75,
139 		.lmtemp_getlim = lmtemp_getlim_lm75,
140 		.lmtemp_setlim = lmtemp_setlim_lm75,
141 	},
142 [lmtemp_ds75] =
143 	{
144 		.lmtemp_name = "DS75",
145 		.lmtemp_addrmask = LM75_ADDRMASK,
146 		.lmtemp_addr = LM75_ADDR,
147 		.lmtemp_decode = lmtemp_decode_ds75,
148 		.lmtemp_encode = lmtemp_encode_ds75,
149 		.lmtemp_getlim = lmtemp_getlim_lm75,
150 		.lmtemp_setlim = lmtemp_setlim_lm75,
151 	},
152 [lmtemp_lm77] =
153 	{
154 		.lmtemp_name = "LM77",
155 		.lmtemp_addrmask = LM77_ADDRMASK,
156 		.lmtemp_addr = LM77_ADDR,
157 		.lmtemp_decode = lmtemp_decode_lm77,
158 		.lmtemp_encode = lmtemp_encode_lm77,
159 		.lmtemp_getlim = lmtemp_getlim_lm77,
160 		.lmtemp_setlim = lmtemp_setlim_lm77,
161 	},
162 };
163 
164 static int
165 lmtemp_match(device_t parent, cfdata_t cf, void *aux)
166 {
167 	struct i2c_attach_args *ia = aux;
168 	int i, match_result;
169 
170 	if (iic_use_direct_match(ia, cf, compat_data, &match_result))
171 		return match_result;
172 
173 	/*
174 	 * Indirect config - not much we can do!
175 	 */
176 	for (i = 0; i < __arraycount(lmtemptbl); i++) {
177 		if (i == cf->cf_flags) {
178 			break;
179 		}
180 	}
181 	if (i == __arraycount(lmtemptbl)) {
182 		return 0;
183 	}
184 
185 	if ((ia->ia_addr & lmtemptbl[i].lmtemp_addrmask) ==
186 	    lmtemptbl[i].lmtemp_addr)
187 		return I2C_MATCH_ADDRESS_ONLY;
188 
189 	return 0;
190 }
191 
192 static void
193 lmtemp_attach(device_t parent, device_t self, void *aux)
194 {
195 	struct lmtemp_softc *sc = device_private(self);
196 	struct i2c_attach_args *ia = aux;
197 	const struct device_compatible_entry *dce;
198 	char name[64];
199 	const char *desc;
200 	int i;
201 
202 	sc->sc_dev = self;
203 	dce = iic_compatible_lookup(ia, compat_data);
204 	if (dce != NULL) {
205 		i = (int)dce->value;
206 	} else {
207 		for (i = 0; i < __arraycount(lmtemptbl); i++) {
208 			if (i == device_cfdata(self)->cf_flags) {
209 				break;
210 			}
211 		}
212 		KASSERT(i < __arraycount(lmtemptbl));
213 	}
214 
215 	sc->sc_tag = ia->ia_tag;
216 	sc->sc_address = ia->ia_addr;
217 	sc->sc_prop = ia->ia_prop;
218 
219 	if (ia->ia_prop != NULL) prop_object_retain(sc->sc_prop);
220 
221 	aprint_naive(": Temperature Sensor\n");
222 	if (ia->ia_name) {
223 		aprint_normal(": %s %s Temperature Sensor\n", ia->ia_name,
224 			lmtemptbl[i].lmtemp_name);
225 	} else {
226 		aprint_normal(": %s Temperature Sensor\n",
227 			lmtemptbl[i].lmtemp_name);
228 	}
229 
230 	sc->sc_lmtemp_decode = lmtemptbl[i].lmtemp_decode;
231 	sc->sc_lmtemp_encode = lmtemptbl[i].lmtemp_encode;
232 
233 	if (iic_acquire_bus(sc->sc_tag, 0)) {
234 		aprint_error_dev(self,
235 		    "unable to acquire I2C bus\n");
236 		return;
237 	}
238 
239 	/* Read temperature limit(s) and remember initial value(s). */
240 	if (i == lmtemp_lm77) {
241 		if (lmtemp_temp_read(sc, LM77_REG_TCRIT_SET_POINT,
242 		    &sc->sc_scrit, 1) != 0) {
243 			aprint_error_dev(self,
244 			    "unable to read low register\n");
245 			iic_release_bus(sc->sc_tag, 0);
246 			return;
247 		}
248 		if (lmtemp_temp_read(sc, LM77_REG_TLOW_SET_POINT,
249 		    &sc->sc_smin, 1) != 0) {
250 			aprint_error_dev(self,
251 			    "unable to read low register\n");
252 			iic_release_bus(sc->sc_tag, 0);
253 			return;
254 		}
255 		if (lmtemp_temp_read(sc, LM77_REG_THIGH_SET_POINT,
256 		    &sc->sc_smax, 1) != 0) {
257 			aprint_error_dev(self,
258 			    "unable to read high register\n");
259 			iic_release_bus(sc->sc_tag, 0);
260 			return;
261 		}
262 	} else {	/* LM75 or compatible */
263 		if (lmtemp_temp_read(sc, LM75_REG_TOS_SET_POINT,
264 		    &sc->sc_smax, 1) != 0) {
265 			aprint_error_dev(self, "unable to read Tos register\n");
266 			iic_release_bus(sc->sc_tag, 0);
267 			return;
268 		}
269 	}
270 	sc->sc_tmax = sc->sc_smax;
271 
272 	if (i == lmtemp_lm75)
273 		lmtemp_setup_sysctl(sc);
274 
275 	/* Set the configuration of the LM75 to defaults. */
276 	if (lmtemp_config_write(sc, LM75_CONFIG_FAULT_QUEUE_4) != 0) {
277 		aprint_error_dev(self, "unable to write config register\n");
278 		iic_release_bus(sc->sc_tag, 0);
279 		return;
280 	}
281 	iic_release_bus(sc->sc_tag, 0);
282 
283 	sc->sc_sme = sysmon_envsys_create();
284 	/* Initialize sensor data. */
285 	sc->sc_sensor.units = ENVSYS_STEMP;
286 	sc->sc_sensor.state = ENVSYS_SINVALID;
287 	sc->sc_sensor.flags = ENVSYS_FMONLIMITS | ENVSYS_FHAS_ENTROPY;
288 
289 	(void)strlcpy(name,
290 	    ia->ia_name? ia->ia_name : device_xname(self),
291 	    sizeof(sc->sc_sensor.desc));
292 
293 	if (prop_dictionary_get_string(sc->sc_prop, "s00", &desc)) {
294 		strncpy(name, desc, 64);
295 	}
296 
297 	(void)strlcpy(sc->sc_sensor.desc, name,
298 	    sizeof(sc->sc_sensor.desc));
299 	if (sysmon_envsys_sensor_attach(sc->sc_sme, &sc->sc_sensor)) {
300 		sysmon_envsys_destroy(sc->sc_sme);
301 		return;
302 	}
303 
304 	/* Hook into system monitor. */
305 	sc->sc_sme->sme_name = device_xname(self);
306 	sc->sc_sme->sme_cookie = sc;
307 	sc->sc_sme->sme_refresh = lmtemp_refresh;
308 	sc->sc_sme->sme_get_limits = lmtemptbl[i].lmtemp_getlim;
309 	sc->sc_sme->sme_set_limits = lmtemptbl[i].lmtemp_setlim;
310 
311 	if (sysmon_envsys_register(sc->sc_sme)) {
312 		aprint_error_dev(self, "unable to register with sysmon\n");
313 		sysmon_envsys_destroy(sc->sc_sme);
314 	}
315 }
316 
317 static int
318 lmtemp_config_write(struct lmtemp_softc *sc, uint8_t val)
319 {
320 	uint8_t cmdbuf[2];
321 
322 	cmdbuf[0] = LM75_REG_CONFIG;
323 	cmdbuf[1] = val;
324 
325 	return iic_exec(sc->sc_tag, I2C_OP_WRITE_WITH_STOP,
326 	    sc->sc_address, cmdbuf, 1, &cmdbuf[1], 1, 0);
327 }
328 
329 static int
330 lmtemp_temp_write(struct lmtemp_softc *sc, uint8_t reg, uint32_t val, int degc)
331 {
332 	uint8_t cmdbuf[3];
333 
334 	cmdbuf[0] = reg;
335 	sc->sc_lmtemp_encode(val, &cmdbuf[1], degc);
336 
337 	return iic_exec(sc->sc_tag, I2C_OP_WRITE_WITH_STOP,
338 	    sc->sc_address, cmdbuf, 1, &cmdbuf[1], 2, 0);
339 }
340 
341 static int
342 lmtemp_temp_read(struct lmtemp_softc *sc, uint8_t which, uint32_t *valp,
343     int degc)
344 {
345 	int error;
346 	uint8_t cmdbuf[1];
347 	uint8_t buf[LM75_TEMP_LEN];
348 
349 	cmdbuf[0] = which;
350 
351 	error = iic_exec(sc->sc_tag, I2C_OP_READ_WITH_STOP,
352 	    sc->sc_address, cmdbuf, 1, buf, LM75_TEMP_LEN, 0);
353 	if (error)
354 		return error;
355 
356 	*valp = sc->sc_lmtemp_decode(buf, degc);
357 	return 0;
358 }
359 
360 static void
361 lmtemp_refresh_sensor_data(struct lmtemp_softc *sc)
362 {
363 	uint32_t val;
364 	int error;
365 
366 	error = lmtemp_temp_read(sc, LM75_REG_TEMP, &val, 0);
367 	if (error) {
368 #if 0
369 		aprint_error_dev(sc->sc_dev, "unable to read temperature, error = %d\n",
370 		    error);
371 #endif
372 		sc->sc_sensor.state = ENVSYS_SINVALID;
373 		return;
374 	}
375 
376 	sc->sc_sensor.value_cur = val;
377 	sc->sc_sensor.state = ENVSYS_SVALID;
378 }
379 
380 static void
381 lmtemp_refresh(struct sysmon_envsys *sme, envsys_data_t *edata)
382 {
383 	struct lmtemp_softc *sc = sme->sme_cookie;
384 
385 	if (iic_acquire_bus(sc->sc_tag, 0))	/* also locks our instance */
386 		return;
387 	lmtemp_refresh_sensor_data(sc);
388 	iic_release_bus(sc->sc_tag, 0);	/* also unlocks our instance */
389 }
390 
391 static void
392 lmtemp_getlim_lm75(struct sysmon_envsys *sme, envsys_data_t *edata,
393     sysmon_envsys_lim_t *limits, uint32_t *props)
394 {
395 	struct lmtemp_softc *sc = sme->sme_cookie;
396 	uint32_t val;
397 
398 	*props &= ~(PROP_CRITMAX);
399 
400 	if (iic_acquire_bus(sc->sc_tag, 0))
401 		return;
402 	if (lmtemp_temp_read(sc, LM75_REG_TOS_SET_POINT, &val, 0) == 0) {
403 		limits->sel_critmax = val;
404 		*props |= PROP_CRITMAX;
405 	}
406 	iic_release_bus(sc->sc_tag, 0);
407 }
408 
409 static void
410 lmtemp_getlim_lm77(struct sysmon_envsys *sme, envsys_data_t *edata,
411     sysmon_envsys_lim_t *limits, uint32_t *props)
412 {
413 	struct lmtemp_softc *sc = sme->sme_cookie;
414 	uint32_t val;
415 
416 	*props &= ~(PROP_CRITMAX | PROP_WARNMAX | PROP_WARNMIN);
417 
418 	if (iic_acquire_bus(sc->sc_tag, 0))
419 		return;
420 	if (lmtemp_temp_read(sc, LM77_REG_TCRIT_SET_POINT, &val, 0) == 0) {
421 		limits->sel_critmax = val;
422 		*props |= PROP_CRITMAX;
423 	}
424 	if (lmtemp_temp_read(sc, LM77_REG_THIGH_SET_POINT, &val, 0) == 0) {
425 		limits->sel_warnmax = val;
426 		*props |= PROP_WARNMAX;
427 	}
428 	if (lmtemp_temp_read(sc, LM77_REG_TLOW_SET_POINT, &val, 0) == 0) {
429 		limits->sel_warnmin = val;
430 		*props |= PROP_WARNMIN;
431 	}
432 	iic_release_bus(sc->sc_tag, 0);
433 }
434 
435 static void
436 lmtemp_setlim_lm75(struct sysmon_envsys *sme, envsys_data_t *edata,
437     sysmon_envsys_lim_t *limits, uint32_t *props)
438 {
439 	struct lmtemp_softc *sc = sme->sme_cookie;
440 	int32_t limit;
441 
442 	if (*props & PROP_CRITMAX) {
443 		if (limits == NULL)	/* Restore defaults */
444 			limit = sc->sc_smax;
445 		else
446 			limit = limits->sel_critmax;
447 		if (iic_acquire_bus(sc->sc_tag, 0))
448 			return;
449 		lmtemp_temp_write(sc, LM75_REG_THYST_SET_POINT,
450 		    limit - 5000000, 0);
451 		lmtemp_temp_write(sc, LM75_REG_TOS_SET_POINT, limit, 0);
452 		iic_release_bus(sc->sc_tag, 0);
453 
454 		/* Synchronise sysctl */
455 		sc->sc_tmax = (limit - 273150000) / 1000000;
456 	}
457 }
458 
459 static void
460 lmtemp_setlim_lm77(struct sysmon_envsys *sme, envsys_data_t *edata,
461     sysmon_envsys_lim_t *limits, uint32_t *props)
462 {
463 	struct lmtemp_softc *sc = sme->sme_cookie;
464 	int32_t limit;
465 
466 	iic_acquire_bus(sc->sc_tag, 0);
467 	if (*props & PROP_CRITMAX) {
468 		if (limits == NULL)	/* Restore defaults */
469 			limit = sc->sc_scrit;
470 		else
471 			limit = limits->sel_critmax;
472 		lmtemp_temp_write(sc, LM77_REG_TCRIT_SET_POINT, limit, 0);
473 	}
474 	if (*props & PROP_WARNMAX) {
475 		if (limits == NULL)	/* Restore defaults */
476 			limit = sc->sc_smax;
477 		else
478 			limit = limits->sel_warnmax;
479 		lmtemp_temp_write(sc, LM77_REG_THIGH_SET_POINT, limit, 0);
480 	}
481 	if (*props & PROP_WARNMIN) {
482 		if (limits == NULL)	/* Restore defaults */
483 			limit = sc->sc_smin;
484 		else
485 			limit = limits->sel_warnmin;
486 		lmtemp_temp_write(sc, LM77_REG_TLOW_SET_POINT, limit, 0);
487 	}
488 	iic_release_bus(sc->sc_tag, 0);
489 }
490 
491 static uint32_t
492 lmtemp_decode_lm75(const uint8_t *buf, int degc)
493 {
494 	int temp;
495 	uint32_t val;
496 
497 	/*
498 	 * LM75 temps are the most-significant 9 bits of a 16-bit reg.
499 	 * sign-extend the MSB and add in the 0.5 from the LSB
500 	 */
501 	temp = (int8_t) buf[0];
502 	temp = (temp << 1) + ((buf[1] >> 7) & 0x1);
503 
504 	/* Temp is given in 1/2 deg. C, we convert to C or uK. */
505 	if (degc)
506 		val = temp / 2;
507 	else
508 		val = temp * 500000 + 273150000;
509 
510 	return val;
511 }
512 
513 static uint32_t
514 lmtemp_decode_ds75(const uint8_t *buf, int degc)
515 {
516 	int temp;
517 
518 	/*
519 	 * Sign-extend the MSB byte, and add in the fractions of a
520 	 * degree contained in the LSB (precision 1/16th DegC).
521 	 */
522 	temp = (int8_t)buf[0];
523 	temp = (temp << 4) | ((buf[1] >> 4) & 0xf);
524 
525 	/*
526 	 * Conversion to C or uK is simple.
527 	 */
528 	if (degc)
529 		return temp / 16;
530 	else
531 		return (temp * 62500 + 273150000);
532 }
533 
534 static uint32_t
535 lmtemp_decode_lm77(const uint8_t *buf, int degc)
536 {
537 	int temp;
538 	uint32_t val;
539 
540 	/*
541 	 * Describe each bits of temperature registers on LM77.
542 	 *   D15 - D12:	Sign
543 	 *   D11 - D3 :	Bit8(MSB) - Bit0
544 	 */
545 	temp = (int8_t)buf[0];
546 	temp = (temp << 5) | ((buf[1] >> 3) & 0x1f);
547 
548 	/* Temp is given in 1/2 deg. C, we convert to C or uK. */
549 	if (degc)
550 		val = temp / 2;
551 	else
552 		val = temp * 500000 + 273150000;
553 
554 	return val;
555 }
556 
557 static void lmtemp_encode_lm75(const uint32_t val, uint8_t *buf, int degc)
558 {
559 	int temp;
560 
561 	/* Convert from C or uK to register format */
562 	if (degc)
563 		temp = val * 2;
564 	else
565 		temp = (val - 273150000) / 500000;
566 	buf[0] = (temp >> 1) & 0xff;
567 	buf[1] = (temp & 1) << 7;
568 }
569 
570 static void lmtemp_encode_ds75(const uint32_t val, uint8_t *buf, int degc)
571 {
572 	int temp;
573 
574 	/* Convert from C or uK to register format */
575 	if (degc)
576 		temp = val * 16;
577 	else
578 		temp = (val - 273150000) / 62500;
579 	buf[0] = (temp >> 4) & 0xff;
580 	buf[1] = (temp & 0xf) << 4;
581 }
582 
583 static void lmtemp_encode_lm77(const uint32_t val, uint8_t *buf, int degc)
584 {
585 	int temp;
586 
587 	/* Convert from C or uK to register format */
588 	if (degc)
589 		temp = val * 2;
590 	else
591 		temp = (val - 273150000) / 500000;
592 	buf[0] = (temp >> 5) & 0xff;
593 	buf[1] = (temp & 0x1f) << 3;
594 }
595 
596 static void
597 lmtemp_setup_sysctl(struct lmtemp_softc *sc)
598 {
599 	const struct sysctlnode *me = NULL, *node = NULL;
600 
601 	sysctl_createv(NULL, 0, NULL, &me,
602 	    CTLFLAG_READWRITE,
603 	    CTLTYPE_NODE, device_xname(sc->sc_dev), NULL,
604 	    NULL, 0, NULL, 0,
605 	    CTL_MACHDEP, CTL_CREATE, CTL_EOL);
606 
607 	sysctl_createv(NULL, 0, NULL, &node,
608 	    CTLFLAG_READWRITE | CTLFLAG_OWNDESC,
609 	    CTLTYPE_INT, "temp", "Threshold temperature",
610 	    sysctl_lm75_temp, 1, (void *)sc, 0,
611 	    CTL_MACHDEP, me->sysctl_num, CTL_CREATE, CTL_EOL);
612 }
613 
614 static int
615 sysctl_lm75_temp(SYSCTLFN_ARGS)
616 {
617 	struct sysctlnode node = *rnode;
618 	struct lmtemp_softc *sc = node.sysctl_data;
619 	int temp, error;
620 
621 	if (newp) {
622 
623 		/* we're asked to write */
624 		node.sysctl_data = &sc->sc_tmax;
625 		if (sysctl_lookup(SYSCTLFN_CALL(&node)) == 0) {
626 
627 			temp = *(int *)node.sysctl_data;
628 			sc->sc_tmax = temp;
629 			error = iic_acquire_bus(sc->sc_tag, 0);
630 			if (error)
631 				return error;
632 			lmtemp_temp_write(sc, LM75_REG_THYST_SET_POINT,
633 			    sc->sc_tmax - 5, 1);
634 			lmtemp_temp_write(sc, LM75_REG_TOS_SET_POINT,
635 			    sc->sc_tmax, 1);
636 			iic_release_bus(sc->sc_tag, 0);
637 
638 			/* Synchronise envsys - calls lmtemp_getlim_lm75() */
639 			sysmon_envsys_update_limits(sc->sc_sme, &sc->sc_sensor);
640 			return 0;
641 		}
642 		return EINVAL;
643 	} else {
644 
645 		node.sysctl_data = &sc->sc_tmax;
646 		node.sysctl_size = 4;
647 		return (sysctl_lookup(SYSCTLFN_CALL(&node)));
648 	}
649 
650 	return 0;
651 }
652 
653 SYSCTL_SETUP(sysctl_lmtemp_setup, "sysctl lmtemp subtree setup")
654 {
655 
656 	sysctl_createv(NULL, 0, NULL, NULL,
657 		       CTLFLAG_PERMANENT,
658 		       CTLTYPE_NODE, "machdep", NULL,
659 		       NULL, 0, NULL, 0,
660 		       CTL_MACHDEP, CTL_EOL);
661 }
662 
663 
664