hwmon: (lm90) Add support for ADT7421

ADT7421 is similar to ADT7461A but supports configurable Beta Compensation.
Packet Error Checking (PEC) is supported but undocumented.

A devicetree node is not added for the added chip since it is quite
unlikely that such an old chip will ever be used in a devicetree based
system. It can be added later if needed.

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

diff --git a/drivers/hwmon/lm90.c b/drivers/hwmon/lm90.c
index a553c611624b61831ce97e90087a5b7891fc7816..c7bf288c8401648d1ab777f650b790ffd6a238b2 100644 (file)
--- a/drivers/hwmon/lm90.c
+++ b/drivers/hwmon/lm90.c
@@ -231,6 +231,7 @@ static const struct i2c_device_id lm90_id[] = {
        { "adm1021", max1617 },
        { "adm1023", adm1023 },
        { "adm1032", adm1032 },
+       { "adt7421", adt7461a },
        { "adt7461", adt7461 },
        { "adt7461a", adt7461a },
        { "adt7481", adt7481 },
@@ -1818,11 +1819,18 @@ static const char *lm90_detect_analog(struct i2c_client *client, bool common_add
                return NULL;
 
        switch (chip_id) {
-       case 0x00 ... 0x0f:     /* ADM1021, undocumented */
+       case 0x00 ... 0x03:     /* ADM1021 */
+       case 0x05 ... 0x0f:
                if (man_id2 == 0x00 && chip_id2 == 0x00 && common_address &&
                    !(status & 0x03) && !(config1 & 0x3f) && !(convrate & 0xf8))
                        name = "adm1021";
                break;
+       case 0x04:              /* ADT7421 (undocumented) */
+               if (man_id2 == 0x41 && chip_id2 == 0x21 &&
+                   (address == 0x4c || address == 0x4d) &&
+                   (config1 & 0x0b) == 0x08 && convrate <= 0x0a)
+                       name = "adt7421";
+               break;
        case 0x30 ... 0x3e:     /* ADM1021A, ADM1023 */
                /*
                 * ADM1021A and compatible chips will be mis-detected as