hwmon: (emc1403) Add EMC1423 support

EMC1423 uses the similar register and adds a hardware shutdown pin to
protect exceed temperature. This function is set by resistor; it's not
necessary to do anything in the driver except add the emc1423 pid of 0x23.

Signed-off-by: Jekyll Lai <[e-mail]>
[Updated Kconfig/comments and minor further changes asked for by the hwmon
maintainers]
Signed-off-by: Alan Cox <[e-mail]>
[Fixed checkpatch warning]
Signed-of--by: Jean Delvare <[e-mail]>

drivers/hwmon/Kconfig

···
 	  will be called dme1737.
 
 config SENSORS_EMC1403
-	tristate "SMSC EMC1403 thermal sensor"
+	tristate "SMSC EMC1403/23 thermal sensor"
 	depends on I2C
 	help
-	  If you say yes here you get support for the SMSC EMC1403
+	  If you say yes here you get support for the SMSC EMC1403/23
 	  temperature monitoring chip.
 
 	  Threshold values can be configured using sysfs.

drivers/hwmon/emc1403.c

···
 			struct i2c_board_info *info)
 {
 	int id;
-	/* Check if thermal chip is SMSC and EMC1403 */
+	/* Check if thermal chip is SMSC and EMC1403 or EMC1423 */
 
 	id = i2c_smbus_read_byte_data(client, THERMAL_SMSC_ID_REG);
 	if (id != 0x5d)
 		return -ENODEV;
 
+	id = i2c_smbus_read_byte_data(client, THERMAL_PID_REG);
+	switch (id) {
+	case 0x21:
+		strlcpy(info->type, "emc1403", I2C_NAME_SIZE);
+		break;
+	case 0x23:
+		strlcpy(info->type, "emc1423", I2C_NAME_SIZE);
+		break;
 	/* Note: 0x25 is the 1404 which is very similar and this
 	   driver could be extended */
-	id = i2c_smbus_read_byte_data(client, THERMAL_PID_REG);
-	if (id != 0x21)
+	default:
 		return -ENODEV;
+	}
 
 	id = i2c_smbus_read_byte_data(client, THERMAL_REVISION_REG);
 	if (id != 0x01)
 		return -ENODEV;
 
-	strlcpy(info->type, "emc1403", I2C_NAME_SIZE);
 	return 0;
 }
 
···
 
 static const struct i2c_device_id emc1403_idtable[] = {
 	{ "emc1403", 0 },
+	{ "emc1423", 0 },
 	{ }
 };
 MODULE_DEVICE_TABLE(i2c, emc1403_idtable);