7  * Based on the lm83 driver. The LM90 is a sensor chip made by National
9  * one external one) with a 0.125 deg resolution (1 deg for local
10  * temperature) and a 3-4 deg accuracy.
22  * has a higher accuracy.
24  * This driver also supports the ADM1032, a sensor chip made by Analog
25  * Devices. That chip is similar to the LM90, with a few differences
26  * that are not handled by this driver. Among others, it has a higher
33  * in a detection as max6657 if it is on address 0x4c. The extra address
65  * and extended mode. They are mostly compatible with LM90 except for a data
778  * to explicitly ask for a transaction without PEC.
867 	 * For volatile registers we have to use a trick.  in lm90_read16()
869 	 * but we have to beware a conversion could occur between the  in lm90_read16()
876 	 * then we have a valid reading. Otherwise we have to read the low  in lm90_read16()
877 	 * byte again, and now we believe we have a correct reading.  in lm90_read16()
905  * in detection or initialization steps), and while a remote channel other
908  * various registers have different meanings as a result of selecting a
1816 	 * Repeat several times, each time checking against a different  in lm90_detect_lm84()
1828 		/* If any register has a different value, this is not an LM84 */  in lm90_detect_lm84()
1856 	 * A byte read operation repeats the most recent read operation  in lm90_detect_max1617()
1875 	 * A byte read operation repeats the most recent read and should  in lm90_detect_max1617()
1981 	 * for most of the chips, yet appear to return a well defined value.  in lm90_detect_analog()
1983 	 * is undocumented for all chips, but also returns a well defined value.  in lm90_detect_analog()
1991 	 * adm1020	00	00	00	41	39  in lm90_detect_analog()
1992 	 * adm1021	00	00	00	41	03  in lm90_detect_analog()
1993 	 * adm1021a	00	00	00	41	3c  in lm90_detect_analog()
1994 	 * adm1023	00	00	00	41	3c	same as adm1021a  in lm90_detect_analog()
1995 	 * adm1032	00	00	00	41	42  in lm90_detect_analog()
1997 	 * adt7421	21	41	04	41	04  in lm90_detect_analog()
1998 	 * adt7461	00	00	00	41	51  in lm90_detect_analog()
1999 	 * adt7461a	61	41	05	41	57  in lm90_detect_analog()
2000 	 * adt7481	81	41	02	41	62  in lm90_detect_analog()
2001 	 * adt7482	-	-	-	41	65	datasheet  in lm90_detect_analog()
2002 	 *		82	41	05	41	75	real chip  in lm90_detect_analog()
2003 	 * adt7483	83	41	04	41	94  in lm90_detect_analog()
2005 	 * nct72	61	41	07	41	55  in lm90_detect_analog()
2006 	 * nct210	00	00	00	41	3f  in lm90_detect_analog()
2007 	 * nct214	61	41	08	41	5a  in lm90_detect_analog()
2008 	 * nct1008	-	-	-	41	57	datasheet rev. 3  in lm90_detect_analog()
2009 	 *		61	41	06	41	54	real chip  in lm90_detect_analog()
2011 	 * nvt210	-	-	-	41	-	datasheet  in lm90_detect_analog()
2012 	 * nvt211	-	-	-	41	-	datasheet  in lm90_detect_analog()
2032 		 * found to have a Chip ID of 0x3c.  in lm90_detect_analog()
2034 		 * (0x12 .. 0x14), but a chip labeled ADM1021A does support it.  in lm90_detect_analog()
2038 		 * It is currently unknown if there is a means to distinguish  in lm90_detect_analog()
2152 		 * Even though MAX6695 and MAX6696 do not have a chip ID  in lm90_detect_maxim()
2181 		 * unsupported registers were observed to return a fixed value  in lm90_detect_maxim()
2184 		 * "MAX1617" (no "A") were observed to report manufacturer ID  in lm90_detect_maxim()
2209 		 * MAX6690 datasheet lists a chip ID of 0x08, and a chip labeled  in lm90_detect_maxim()
2210 		 * MAX6654 was observed to have a chip ID of 0x09.  in lm90_detect_maxim()
2217 		 * MAX6642, MAX6657, MAX6658 and MAX6659 do NOT have a chip_id  in lm90_detect_maxim()
2221 		 * MAX6642 does not have a conversion rate register, nor low  in lm90_detect_maxim()
2226 		 * a low nibble, so the value will be those of the previous  in lm90_detect_maxim()
2228 		 * MAX6659 has a third set of upper temperature limit registers.  in lm90_detect_maxim()
2239 			 * We know that this is not a MAX6657/58/59 because its  in lm90_detect_maxim()
2241 			 * not appear to have a conversion rate register.  in lm90_detect_maxim()
2244 			/* re-read manufacturer ID to have a good baseline */  in lm90_detect_maxim()
2281 		 * and MAX6649 is at address 0x4c. A slight difference between  in lm90_detect_maxim()
2411 	 * 0x4c and have a chip ID of 0x01. G781-1 is supposed to be at I2C  in lm90_detect_gmt()
2412 	 * address 0x4d and have a chip ID of 0x03. However, when support  in lm90_detect_gmt()
2413 	 * for G781 was added, chips at 0x4c and 0x4d were found to have a  in lm90_detect_gmt()
2414 	 * chip ID of 0x01. A G781-1 at I2C address 0x4d was now found with  in lm90_detect_gmt()
2418 	 * G784 reports manufacturer ID 0x47 and chip ID 0x01. A public  in lm90_detect_gmt()
2522 	 * value. Check again with a different register and handle accordingly.  in lm90_detect()
2648 	 * Note that expeciments with an actual chip do not show a difference  in lm90_init_client()