hwmon: (lm90) Add explicit support for ADM1020

ADM1020 is compatible with ADM1021 but has a separate chip revision and
a limited I2C address range.
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

Documentation/hwmon/lm90.rst

@@ -51,6 +51,14 @@ Supported chips:
 
 	       http://www.national.com/mpf/LM/LM86.html
 
+  * Analog Devices ADM1020
+
+    Prefix: 'adm1020'
+
+    Addresses scanned: I2C 0x4c - 0x4e
+
+    Datasheet: Publicly available at the Analog Devices website
+
   * Analog Devices ADM1021
 
     Prefix: 'adm1021'
@@ -457,7 +465,7 @@ features:
 LM84:
   * 8 bit sensor resolution
 
-ADM1021, GL523SM, MAX1617, NE1617, NE1617A, THMC10:
+ADM1020, ADM1021, GL523SM, MAX1617, NE1617, NE1617A, THMC10:
   * 8 bit sensor resolution
   * Low temperature limits
 

drivers/hwmon/Kconfig

@@ -1360,8 +1360,8 @@ config SENSORS_LM90
 	depends on I2C
 	help
 	  If you say yes here you get support for National Semiconductor LM84,
-	  LM90, LM86, LM89 and LM99, Analog Devices ADM2021, ADM1021A, ADM1023,
-	  ADM1032, ADT7461, ADT7461A, ADT7481, ADT7482, and ADT7483A,
+	  LM90, LM86, LM89 and LM99, Analog Devices ADM1020, ADM2021, ADM1021A,
+	  ADM1023, ADM1032, ADT7461, ADT7461A, ADT7481, ADT7482, and ADT7483A,
 	  Maxim MAX1617, MAX6642, MAX6646, MAX6647, MAX6648, MAX6649, MAX6654,
 	  MAX6657, MAX6658, MAX6659, MAX6680, MAX6681, MAX6692, MAX6695,
 	  MAX6696,

drivers/hwmon/lm90.c

@@ -228,6 +228,7 @@ enum chips { adm1023, adm1032, adt7461, adt7461a, adt7481,
  */
 
 static const struct i2c_device_id lm90_id[] = {
+	{ "adm1020", max1617 },
 	{ "adm1021", max1617 },
 	{ "adm1023", adm1023 },
 	{ "adm1032", adm1032 },
@@ -1831,7 +1832,8 @@ static const char *lm90_detect_analog(struct i2c_client *client, bool common_add
 		    (config1 & 0x0b) == 0x08 && convrate <= 0x0a)
 			name = "adt7421";
 		break;
-	case 0x30 ... 0x3e:	/* ADM1021A, ADM1023 */
+	case 0x30 ... 0x38:	/* ADM1021A, ADM1023 */
+	case 0x3a ... 0x3e:
 		/*
 		 * ADM1021A and compatible chips will be mis-detected as
 		 * ADM1023. Chips labeled 'ADM1021A' and 'ADM1023' were both
@@ -1849,6 +1851,12 @@ static const char *lm90_detect_analog(struct i2c_client *client, bool common_add
 		    !(status & 0x03) && !(config1 & 0x3f) && !(convrate & 0xf8))
 			name = "adm1023";
 		break;
+	case 0x39:		/* ADM1020 (undocumented) */
+		if (man_id2 == 0x00 && chip_id2 == 0x00 &&
+		    (address == 0x4c || address == 0x4d || address == 0x4e) &&
+		    !(status & 0x03) && !(config1 & 0x3f) && !(convrate & 0xf8))
+			name = "adm1020";
+		break;
 	case 0x3f:		/* NCT210 */
 		if (man_id2 == 0x00 && chip_id2 == 0x00 && common_address &&
 		    !(status & 0x03) && !(config1 & 0x3f) && !(convrate & 0xf8))