hwmon: (lm90) Add support for ADM1021, ADM1021A, and ADM1023

Both chips are quite similar to other chips of this series, so add
support for them to the lm90 driver. Also mention ON Semiconductor NCT210,
which is pin and register compatible to ADM1021A.

None of the chips support the secondary manufacturer and chip ID registers
at 0x3e and 0x3f, but return 0 when reading from those registers.
Use that information to improve the accuracy of chip detection code.

Devicetree nodes are not added for the added chips since it is quite
unlikely that such old chips will ever be used in a devicetree based
system. They can be added later if needed.

Signed-off-by: Guenter Roeck <linux@roeck-us.net>

1 files changed, 22 insertions, 1 deletions

diff --git a/Documentation/hwmon/lm90.rst b/Documentation/hwmon/lm90.rst
index e2ee0f2e1b7b..075be136210b 100644
--- a/Documentation/hwmon/lm90.rst
+++ b/Documentation/hwmon/lm90.rst
@@ -51,6 +51,22 @@ Supported chips:
 
 	       http://www.national.com/mpf/LM/LM86.html
 
+  * Analog Devices ADM1021
+
+    Prefix: 'adm1021'
+
+    Addresses scanned: I2C 0x18 - 0x1a, 0x29 - 0x2b, 0x4c - 0x4e
+
+    Datasheet: Publicly available at the Analog Devices website
+
+  * Analog Devices ADM1021A/ADM1023
+
+    Prefix: 'adm1023'
+
+    Addresses scanned: I2C 0x18 - 0x1a, 0x29 - 0x2b, 0x4c - 0x4e
+
+    Datasheet: Publicly available at the Analog Devices website
+
   * Analog Devices ADM1032
 
     Prefix: 'adm1032'
@@ -369,10 +385,15 @@ features:
 LM84:
   * 8 bit sensor resolution
 
-MAX1617:
+ADM1021, MAX1617:
   * 8 bit sensor resolution
   * Low temperature limits
 
+ADM1021A, ADM1023:
+  * Temperature offset register for remote temperature sensor
+  * 11 bit resolution for remote temperature sensor
+  * Low temperature limits
+
 LM90:
   * 11 bit resolution for remote temperature sensor
   * Temperature offset register for remote temperature sensor