hwmon: (pmbus/max31785) Support revision "B"

There was an issue in how the tach feedbacks of dual rotor fans were
reported during any change in fan speeds with revision "A" of the
MAX31785. When the fan speeds would transition to a new target speed,
the rotor not wired to the TACH input when TACHSEL = 0 would report a
speed of 0 until the new target was reached. This has been fixed,
resulting in a revision "B" update where the MFR_REVISION of "B" is
0x3061.
Signed-off-by: Matthew Barth <msbarth@linux.ibm.com>
Link: https://lore.kernel.org/r/20210201212217.73721-1-msbarth@linux.ibm.com
[groeck: Change 'ret' variable type to int]
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

drivers/hwmon/pmbus/max31785.c

@@ -17,6 +17,7 @@ enum max31785_regs {
 
 #define MAX31785			0x3030
 #define MAX31785A			0x3040
+#define MAX31785B			0x3061
 
 #define MFR_FAN_CONFIG_DUAL_TACH	BIT(12)
 
@@ -329,7 +330,7 @@ static int max31785_probe(struct i2c_client *client)
 	struct device *dev = &client->dev;
 	struct pmbus_driver_info *info;
 	bool dual_tach = false;
-	s64 ret;
+	int ret;
 
 	if (!i2c_check_functionality(client->adapter,
 				     I2C_FUNC_SMBUS_BYTE_DATA |
@@ -350,12 +351,14 @@ static int max31785_probe(struct i2c_client *client)
 	if (ret < 0)
 		return ret;
 
-	if (ret == MAX31785A) {
+	if (ret == MAX31785A || ret == MAX31785B) {
 		dual_tach = true;
 	} else if (ret == MAX31785) {
-		if (!strcmp("max31785a", client->name))
-			dev_warn(dev, "Expected max3175a, found max31785: cannot provide secondary tachometer readings\n");
+		if (!strcmp("max31785a", client->name) ||
+		    !strcmp("max31785b", client->name))
+			dev_warn(dev, "Expected max31785a/b, found max31785: cannot provide secondary tachometer readings\n");
 	} else {
+		dev_err(dev, "Unrecognized MAX31785 revision: %x\n", ret);
 		return -ENODEV;
 	}
 
@@ -371,6 +374,7 @@ static int max31785_probe(struct i2c_client *client)
 static const struct i2c_device_id max31785_id[] = {
 	{ "max31785", 0 },
 	{ "max31785a", 0 },
+	{ "max31785b", 0 },
 	{ },
 };
 
@@ -379,6 +383,7 @@ MODULE_DEVICE_TABLE(i2c, max31785_id);
 static const struct of_device_id max31785_of_match[] = {
 	{ .compatible = "maxim,max31785" },
 	{ .compatible = "maxim,max31785a" },
+	{ .compatible = "maxim,max31785b" },
 	{ },
 };