xref: /netbsd-src/sys/dev/i2c/sdtemp.c (revision b1c86f5f087524e68db12794ee9c3e3da1ab17a0)
1 /*      $NetBSD: sdtemp.c,v 1.18 2010/07/29 13:07:14 pgoyette Exp $        */
2 
3 /*
4  * Copyright (c) 2009 The NetBSD Foundation, Inc.
5  * All rights reserved.
6  *
7  * This code is derived from software contributed to The NetBSD Foundation
8  * by Paul Goyette.
9  *
10  * Redistribution and use in source and binary forms, with or without
11  * modification, are permitted provided that the following conditions
12  * are met:
13  * 1. Redistributions of source code must retain the above copyright
14  *    notice, this list of conditions and the following disclaimer.
15  * 2. Redistributions in binary form must reproduce the above copyright
16  *    notice, this list of conditions and the following disclaimer in the
17  *    documentation and/or other materials provided with the distribution.
18  *
19  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
20  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
21  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
22  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
23  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
24  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
25  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
26  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
27  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
28  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
29  * POSSIBILITY OF SUCH DAMAGE.
30  */
31 
32 #include <sys/cdefs.h>
33 __KERNEL_RCSID(0, "$NetBSD: sdtemp.c,v 1.18 2010/07/29 13:07:14 pgoyette Exp $");
34 
35 #include <sys/param.h>
36 #include <sys/systm.h>
37 #include <sys/kmem.h>
38 #include <sys/device.h>
39 #include <sys/kernel.h>
40 #include <sys/endian.h>
41 
42 #include <dev/sysmon/sysmonvar.h>
43 
44 #include <dev/i2c/i2cvar.h>
45 #include <dev/i2c/sdtemp_reg.h>
46 
47 struct sdtemp_softc {
48 	device_t sc_dev;
49 	i2c_tag_t sc_tag;
50 	int sc_address;
51 
52 	struct sysmon_envsys *sc_sme;
53 	envsys_data_t *sc_sensor;
54 	sysmon_envsys_lim_t sc_deflims;
55 	uint32_t sc_defprops;
56 	int sc_resolution;
57 	uint16_t sc_capability;
58 };
59 
60 static int  sdtemp_match(device_t, cfdata_t, void *);
61 static void sdtemp_attach(device_t, device_t, void *);
62 
63 CFATTACH_DECL_NEW(sdtemp, sizeof(struct sdtemp_softc),
64 	sdtemp_match, sdtemp_attach, NULL, NULL);
65 
66 static void	sdtemp_refresh(struct sysmon_envsys *, envsys_data_t *);
67 static void	sdtemp_get_limits(struct sysmon_envsys *, envsys_data_t *,
68 				  sysmon_envsys_lim_t *, uint32_t *);
69 static void	sdtemp_set_limits(struct sysmon_envsys *, envsys_data_t *,
70 				  sysmon_envsys_lim_t *, uint32_t *);
71 #ifdef NOT_YET
72 static int	sdtemp_read_8(struct sdtemp_softc *, uint8_t, uint8_t *);
73 static int	sdtemp_write_8(struct sdtemp_softc *, uint8_t, uint8_t);
74 #endif /* NOT YET */
75 static int	sdtemp_read_16(struct sdtemp_softc *, uint8_t, uint16_t *);
76 static int	sdtemp_write_16(struct sdtemp_softc *, uint8_t, uint16_t);
77 static uint32_t	sdtemp_decode_temp(struct sdtemp_softc *, uint16_t);
78 static bool	sdtemp_pmf_suspend(device_t, const pmf_qual_t *);
79 static bool	sdtemp_pmf_resume(device_t, const pmf_qual_t *);
80 
81 struct sdtemp_dev_entry {
82 	const uint16_t sdtemp_mfg_id;
83 	const uint16_t  sdtemp_devrev;
84 	const uint16_t  sdtemp_mask;
85 	const uint8_t  sdtemp_resolution;
86 	const char    *sdtemp_desc;
87 };
88 
89 /* Convert sysmon_envsys uKelvin value to simple degC */
90 
91 #define	__UK2C(uk) (((uk) - 273150000) / 1000000)
92 
93 /*
94  * List of devices known to conform to JEDEC JC42.4
95  *
96  * NOTE: A non-negative value for resolution indicates that the sensor
97  * resolution is fixed at that number of fractional bits;  a negative
98  * value indicates that the sensor needs to be configured.  In either
99  * case, trip-point registers are fixed at two-bit (0.25C) resolution.
100  */
101 static const struct sdtemp_dev_entry
102 sdtemp_dev_table[] = {
103     { MAXIM_MANUFACTURER_ID, MAX_6604_DEVICE_ID,    MAX_6604_MASK,   3,
104 	"Maxim MAX6604" },
105     { MCP_MANUFACTURER_ID,   MCP_9805_DEVICE_ID,    MCP_9805_MASK,   2,
106 	"Microchip Tech MCP9805/MCP9843" },
107     { MCP_MANUFACTURER_ID,   MCP_98243_DEVICE_ID,   MCP_98243_MASK, -4,
108 	"Microchip Tech MCP98243" },
109     { MCP_MANUFACTURER_ID,   MCP_98242_DEVICE_ID,   MCP_98242_MASK, -4,
110 	"Microchip Tech MCP98242" },
111     { ADT_MANUFACTURER_ID,   ADT_7408_DEVICE_ID,    ADT_7408_MASK,   4,
112 	"Analog Devices ADT7408" },
113     { NXP_MANUFACTURER_ID,   NXP_SE98_DEVICE_ID,    NXP_SE98_MASK,   3,
114 	"NXP Semiconductors SE97B/SE98" },
115     { NXP_MANUFACTURER_ID,   NXP_SE97_DEVICE_ID,    NXP_SE97_MASK,   3,
116 	"NXP Semiconductors SE97" },
117     { STTS_MANUFACTURER_ID,  STTS_424E_DEVICE_ID,   STTS_424E_MASK,  2,
118 	"STmicroelectronics STTS424E" },
119     { STTS_MANUFACTURER_ID,  STTS_424_DEVICE_ID,    STTS_424_MASK,   2,
120 	"STmicroelectronics STTS424" },
121     { CAT_MANUFACTURER_ID,   CAT_34TS02_DEVICE_ID,  CAT_34TS02_MASK, 4,
122 	"Catalyst CAT34TS02/CAT6095" },
123     { IDT_MANUFACTURER_ID,   IDT_TS3000B3_DEVICE_ID, IDT_TS3000B3_MASK, 4,
124 	"Integrated Device Technology TS3000B3/TSE2002B3" },
125     { 0, 0, 0, 2, "Unknown" }
126 };
127 
128 static int
129 sdtemp_lookup(uint16_t mfg, uint16_t devrev)
130 {
131 	int i;
132 
133 	for (i = 0; sdtemp_dev_table[i].sdtemp_mfg_id; i++) {
134 		if (mfg != sdtemp_dev_table[i].sdtemp_mfg_id)
135 			continue;
136 		if ((devrev & sdtemp_dev_table[i].sdtemp_mask) ==
137 		    sdtemp_dev_table[i].sdtemp_devrev)
138 			break;
139 	}
140 
141 	return i;
142 }
143 
144 static int
145 sdtemp_match(device_t parent, cfdata_t cf, void *aux)
146 {
147 	struct i2c_attach_args *ia = aux;
148 	uint16_t mfgid, devid;
149 	struct sdtemp_softc sc;
150 	int i, error;
151 
152 	sc.sc_tag = ia->ia_tag;
153 	sc.sc_address = ia->ia_addr;
154 
155 	if ((ia->ia_addr & SDTEMP_ADDRMASK) != SDTEMP_ADDR)
156 		return 0;
157 
158 	/* Verify that we can read the manufacturer ID  & Device ID */
159 	iic_acquire_bus(sc.sc_tag, 0);
160 	error = sdtemp_read_16(&sc, SDTEMP_REG_MFG_ID,  &mfgid) |
161 		sdtemp_read_16(&sc, SDTEMP_REG_DEV_REV, &devid);
162 	iic_release_bus(sc.sc_tag, 0);
163 
164 	if (error)
165 		return 0;
166 
167 	i = sdtemp_lookup(mfgid, devid);
168 	if (sdtemp_dev_table[i].sdtemp_mfg_id == 0) {
169 		aprint_debug("sdtemp: No match for mfg 0x%04x dev 0x%02x "
170 		    "rev 0x%02x at address 0x%02x\n", mfgid, devid >> 8,
171 		    devid & 0xff, sc.sc_address);
172 		return 0;
173 	}
174 
175 	return 1;
176 }
177 
178 static void
179 sdtemp_attach(device_t parent, device_t self, void *aux)
180 {
181 	struct sdtemp_softc *sc = device_private(self);
182 	struct i2c_attach_args *ia = aux;
183 	uint16_t mfgid, devid;
184 	int i, error;
185 
186 	sc->sc_tag = ia->ia_tag;
187 	sc->sc_address = ia->ia_addr;
188 	sc->sc_dev = self;
189 
190 	iic_acquire_bus(sc->sc_tag, 0);
191 	if ((error = sdtemp_read_16(sc, SDTEMP_REG_MFG_ID,  &mfgid)) != 0 ||
192 	    (error = sdtemp_read_16(sc, SDTEMP_REG_DEV_REV, &devid)) != 0) {
193 		iic_release_bus(sc->sc_tag, 0);
194 		aprint_error(": attach error %d\n", error);
195 		return;
196 	}
197 	i = sdtemp_lookup(mfgid, devid);
198 	sc->sc_resolution =
199 	    sdtemp_dev_table[i].sdtemp_resolution;
200 
201 	aprint_naive(": Temp Sensor\n");
202 	aprint_normal(": %s Temp Sensor\n", sdtemp_dev_table[i].sdtemp_desc);
203 
204 	if (sdtemp_dev_table[i].sdtemp_mfg_id == 0)
205 		aprint_debug_dev(self,
206 		    "mfg 0x%04x dev 0x%02x rev 0x%02x at addr 0x%02x\n",
207 		    mfgid, devid >> 8, devid & 0xff, ia->ia_addr);
208 
209 	/*
210 	 * Alarm capability is required;  if not present, this is likely
211 	 * not a real sdtemp device.
212 	 */
213 	error = sdtemp_read_16(sc, SDTEMP_REG_CAPABILITY, &sc->sc_capability);
214 	if (error != 0 || (sc->sc_capability & SDTEMP_CAP_HAS_ALARM) == 0) {
215 		iic_release_bus(sc->sc_tag, 0);
216 		aprint_error_dev(self,
217 		    "required alarm capability not present!\n");
218 		return;
219 	}
220 	/* Set the configuration to defaults. */
221 	error = sdtemp_write_16(sc, SDTEMP_REG_CONFIG, 0);
222 	if (error != 0) {
223 		iic_release_bus(sc->sc_tag, 0);
224 		aprint_error_dev(self, "error %d writing config register\n",
225 		    error);
226 		return;
227 	}
228 	/* If variable resolution, set to max */
229 	if (sc->sc_resolution < 0) {
230 		sc->sc_resolution = ~sc->sc_resolution;
231 		error = sdtemp_write_16(sc, SDTEMP_REG_RESOLUTION,
232 					sc->sc_resolution & 0x3);
233 		if (error != 0) {
234 			iic_release_bus(sc->sc_tag, 0);
235 			aprint_error_dev(self,
236 			    "error %d writing resolution register\n", error);
237 			return;
238 		} else
239 			sc->sc_resolution++;
240 	}
241 	iic_release_bus(sc->sc_tag, 0);
242 
243 	/* Hook us into the sysmon_envsys subsystem */
244 	sc->sc_sme = sysmon_envsys_create();
245 	sc->sc_sme->sme_name = device_xname(self);
246 	sc->sc_sme->sme_cookie = sc;
247 	sc->sc_sme->sme_refresh = sdtemp_refresh;
248 	sc->sc_sme->sme_get_limits = sdtemp_get_limits;
249 	sc->sc_sme->sme_set_limits = sdtemp_set_limits;
250 
251 	sc->sc_sensor = kmem_zalloc(sizeof(envsys_data_t), KM_NOSLEEP);
252 	if (!sc->sc_sensor) {
253 		aprint_error_dev(self, "unable to allocate sc_sensor\n");
254 		goto bad2;
255 	}
256 
257 	/* Initialize sensor data. */
258 	sc->sc_sensor->units =  ENVSYS_STEMP;
259 	sc->sc_sensor->state = ENVSYS_SINVALID;
260 	sc->sc_sensor->flags |= ENVSYS_FMONLIMITS;
261 	(void)strlcpy(sc->sc_sensor->desc, device_xname(self),
262 	    sizeof(sc->sc_sensor->desc));
263 
264 	/* Now attach the sensor */
265 	if (sysmon_envsys_sensor_attach(sc->sc_sme, sc->sc_sensor)) {
266 		aprint_error_dev(self, "unable to attach sensor\n");
267 		goto bad;
268 	}
269 
270 	/* Register the device */
271 	error = sysmon_envsys_register(sc->sc_sme);
272 	if (error) {
273 		aprint_error_dev(self, "error %d registering with sysmon\n",
274 		    error);
275 		goto bad;
276 	}
277 
278 	if (!pmf_device_register(self, sdtemp_pmf_suspend, sdtemp_pmf_resume))
279 		aprint_error_dev(self, "couldn't establish power handler\n");
280 
281 	/* Retrieve and display hardware monitor limits */
282 	sdtemp_get_limits(sc->sc_sme, sc->sc_sensor, &sc->sc_deflims,
283 	    &sc->sc_defprops);
284 	aprint_normal_dev(self, "");
285 	i = 0;
286 	if (sc->sc_defprops & PROP_WARNMIN) {
287 		aprint_normal("low limit %dC",
288 		              __UK2C(sc->sc_deflims.sel_warnmin));
289 		i++;
290 	}
291 	if (sc->sc_defprops & PROP_WARNMAX) {
292 		aprint_normal("%shigh limit %dC ", (i)?", ":"",
293 			      __UK2C(sc->sc_deflims.sel_warnmax));
294 		i++;
295 	}
296 	if (sc->sc_defprops & PROP_CRITMAX) {
297 		aprint_normal("%scritical limit %dC ", (i)?", ":"",
298 			      __UK2C(sc->sc_deflims.sel_critmax));
299 		i++;
300 	}
301 	if (i == 0)
302 		aprint_normal("no hardware limits set\n");
303 	else
304 		aprint_normal("\n");
305 
306 	return;
307 
308 bad:
309 	kmem_free(sc->sc_sensor, sizeof(envsys_data_t));
310 bad2:
311 	sysmon_envsys_destroy(sc->sc_sme);
312 }
313 
314 /* Retrieve current limits from device, and encode in uKelvins */
315 static void
316 sdtemp_get_limits(struct sysmon_envsys *sme, envsys_data_t *edata,
317 		  sysmon_envsys_lim_t *limits, uint32_t *props)
318 {
319 	struct sdtemp_softc *sc = sme->sme_cookie;
320 	uint16_t lim;
321 
322 	*props = 0;
323 	iic_acquire_bus(sc->sc_tag, 0);
324 	if (sdtemp_read_16(sc, SDTEMP_REG_LOWER_LIM, &lim) == 0 && lim != 0) {
325 		limits->sel_warnmin = sdtemp_decode_temp(sc, lim);
326 		*props |= PROP_WARNMIN;
327 	}
328 	if (sdtemp_read_16(sc, SDTEMP_REG_UPPER_LIM, &lim) == 0 && lim != 0) {
329 		limits->sel_warnmax = sdtemp_decode_temp(sc, lim);
330 		*props |= PROP_WARNMAX;
331 	}
332 	if (sdtemp_read_16(sc, SDTEMP_REG_CRIT_LIM, &lim) == 0 && lim != 0) {
333 		limits->sel_critmax = sdtemp_decode_temp(sc, lim);
334 		*props |= PROP_CRITMAX;
335 	}
336 	iic_release_bus(sc->sc_tag, 0);
337 	if (*props != 0)
338 		*props |= PROP_DRIVER_LIMITS;
339 }
340 
341 /* Send current limit values to the device */
342 static void
343 sdtemp_set_limits(struct sysmon_envsys *sme, envsys_data_t *edata,
344 		  sysmon_envsys_lim_t *limits, uint32_t *props)
345 {
346 	uint16_t val;
347 	struct sdtemp_softc *sc = sme->sme_cookie;
348 
349 	if (limits == NULL) {
350 		limits = &sc->sc_deflims;
351 		props  = &sc->sc_defprops;
352 	}
353 	iic_acquire_bus(sc->sc_tag, 0);
354 	if (*props & PROP_WARNMIN) {
355 		val = __UK2C(limits->sel_warnmin);
356 		(void)sdtemp_write_16(sc, SDTEMP_REG_LOWER_LIM,
357 					(val << 4) & SDTEMP_TEMP_MASK);
358 	}
359 	if (*props & PROP_WARNMAX) {
360 		val = __UK2C(limits->sel_warnmax);
361 		(void)sdtemp_write_16(sc, SDTEMP_REG_UPPER_LIM,
362 					(val << 4) & SDTEMP_TEMP_MASK);
363 	}
364 	if (*props & PROP_CRITMAX) {
365 		val = __UK2C(limits->sel_critmax);
366 		(void)sdtemp_write_16(sc, SDTEMP_REG_CRIT_LIM,
367 					(val << 4) & SDTEMP_TEMP_MASK);
368 	}
369 	iic_release_bus(sc->sc_tag, 0);
370 
371 	/*
372 	 * If at least one limit is set that we can handle, and no
373 	 * limits are set that we cannot handle, tell sysmon that
374 	 * the driver will take care of monitoring the limits!
375 	 */
376 	if (*props & (PROP_CRITMIN | PROP_BATTCAP | PROP_BATTWARN))
377 		*props &= ~PROP_DRIVER_LIMITS;
378 	else if (*props & PROP_LIMITS)
379 		*props |= PROP_DRIVER_LIMITS;
380 	else
381 		*props &= ~PROP_DRIVER_LIMITS;
382 }
383 
384 #ifdef NOT_YET	/* All registers on these sensors are 16-bits */
385 
386 /* Read a 8-bit value from a register */
387 static int
388 sdtemp_read_8(struct sdtemp_softc *sc, uint8_t reg, uint8_t *valp)
389 {
390 	int error;
391 
392 	error = iic_exec(sc->sc_tag, I2C_OP_READ_WITH_STOP,
393 	    sc->sc_address, &reg, 1, valp, sizeof(*valp), 0);
394 
395 	return error;
396 }
397 
398 static int
399 sdtemp_write_8(struct sdtemp_softc *sc, uint8_t reg, uint8_t val)
400 {
401 	return iic_exec(sc->sc_tag, I2C_OP_WRITE_WITH_STOP,
402 	    sc->sc_address, &reg, 1, &val, sizeof(val), 0);
403 }
404 #endif /* NOT_YET */
405 
406 /* Read a 16-bit value from a register */
407 static int
408 sdtemp_read_16(struct sdtemp_softc *sc, uint8_t reg, uint16_t *valp)
409 {
410 	int error;
411 
412 	error = iic_exec(sc->sc_tag, I2C_OP_READ_WITH_STOP,
413 	    sc->sc_address, &reg, 1, valp, sizeof(*valp), 0);
414 	if (error)
415 		return error;
416 
417 	*valp = be16toh(*valp);
418 
419 	return 0;
420 }
421 
422 static int
423 sdtemp_write_16(struct sdtemp_softc *sc, uint8_t reg, uint16_t val)
424 {
425 	uint16_t temp;
426 
427 	temp = htobe16(val);
428 	return iic_exec(sc->sc_tag, I2C_OP_WRITE_WITH_STOP,
429 	    sc->sc_address, &reg, 1, &temp, sizeof(temp), 0);
430 }
431 
432 static uint32_t
433 sdtemp_decode_temp(struct sdtemp_softc *sc, uint16_t temp)
434 {
435 	uint32_t val;
436 	int32_t stemp;
437 
438 	/* Get only the temperature bits */
439 	temp &= SDTEMP_TEMP_MASK;
440 
441 	/* If necessary, extend the sign bit */
442 	if ((sc->sc_capability & SDTEMP_CAP_WIDER_RANGE) &&
443 	    (temp & SDTEMP_TEMP_NEGATIVE))
444 		temp |= SDTEMP_TEMP_SIGN_EXT;
445 
446 	/* Mask off only bits valid within current resolution */
447 	temp &= ~(0xf >> sc->sc_resolution);
448 
449 	/* Treat as signed and extend to 32-bits */
450 	stemp = (int16_t)temp;
451 
452 	/* Now convert from 0.0625 (1/16) deg C increments to microKelvins */
453 	val = (stemp * 62500) + 273150000;
454 
455 	return val;
456 }
457 
458 static void
459 sdtemp_refresh(struct sysmon_envsys *sme, envsys_data_t *edata)
460 {
461 	struct sdtemp_softc *sc = sme->sme_cookie;
462 	uint16_t val;
463 	int error;
464 
465 	iic_acquire_bus(sc->sc_tag, 0);
466 	error = sdtemp_read_16(sc, SDTEMP_REG_AMBIENT_TEMP, &val);
467 	iic_release_bus(sc->sc_tag, 0);
468 
469 	if (error) {
470 		edata->state = ENVSYS_SINVALID;
471 		return;
472 	}
473 
474 	edata->value_cur = sdtemp_decode_temp(sc, val);
475 
476 	/* Now check for limits */
477 	if ((edata->upropset & PROP_DRIVER_LIMITS) == 0)
478 		edata->state = ENVSYS_SVALID;
479 	else if ((val & SDTEMP_ABOVE_CRIT) &&
480 		    (edata->upropset & PROP_CRITMAX))
481 		edata->state = ENVSYS_SCRITOVER;
482 	else if ((val & SDTEMP_ABOVE_UPPER) &&
483 		    (edata->upropset & PROP_WARNMAX))
484 		edata->state = ENVSYS_SWARNOVER;
485 	else if ((val & SDTEMP_BELOW_LOWER) &&
486 		    (edata->upropset & PROP_WARNMIN))
487 		edata->state = ENVSYS_SWARNUNDER;
488 	else
489 		edata->state = ENVSYS_SVALID;
490 }
491 
492 /*
493  * power management functions
494  *
495  * We go into "shutdown" mode at suspend time, and return to normal
496  * mode upon resume.  This reduces power consumption by disabling
497  * the A/D converter.
498  */
499 
500 static bool
501 sdtemp_pmf_suspend(device_t dev, const pmf_qual_t *qual)
502 {
503 	struct sdtemp_softc *sc = device_private(dev);
504 	int error;
505 	uint16_t config;
506 
507 	iic_acquire_bus(sc->sc_tag, 0);
508 	error = sdtemp_read_16(sc, SDTEMP_REG_CONFIG, &config);
509 	if (error == 0) {
510 		config |= SDTEMP_CONFIG_SHUTDOWN_MODE;
511 		error = sdtemp_write_16(sc, SDTEMP_REG_CONFIG, config);
512 	}
513 	iic_release_bus(sc->sc_tag, 0);
514 	return (error == 0);
515 }
516 
517 static bool
518 sdtemp_pmf_resume(device_t dev, const pmf_qual_t *qual)
519 {
520 	struct sdtemp_softc *sc = device_private(dev);
521 	int error;
522 	uint16_t config;
523 
524 	iic_acquire_bus(sc->sc_tag, 0);
525 	error = sdtemp_read_16(sc, SDTEMP_REG_CONFIG, &config);
526 	if (error == 0) {
527 		config &= ~SDTEMP_CONFIG_SHUTDOWN_MODE;
528 		error = sdtemp_write_16(sc, SDTEMP_REG_CONFIG, config);
529 	}
530 	iic_release_bus(sc->sc_tag, 0);
531 	return (error == 0);
532 }
533