@@ -203,21 +203,25 @@ static int tmp421_read(struct device *dev, enum hwmon_sensor_types type,
  	if (ret)
  		return ret;
  
-	if (!tmp421->channel[channel].enabled)
-		return -ENODATA;
-
  	switch (attr) {
  	case hwmon_temp_input:
+		if (!tmp421->channel[channel].enabled)
+			return -ENODATA;
  		*val = temp_from_raw(tmp421->channel[channel].temp,
  				     tmp421->config & TMP421_CONFIG_RANGE);
  		return 0;
  	case hwmon_temp_fault:
+		if (!tmp421->channel[channel].enabled)
+			return -ENODATA;
  		/*
  		 * Any of OPEN or /PVLD bits indicate a hardware mulfunction
  		 * and the conversion result may be incorrect
  		 */
  		*val = !!(tmp421->channel[channel].temp & 0x03);
  		return 0;
+	case hwmon_temp_enable:
+		*val = tmp421->channel[channel].enabled;
+		return 0;
  	default:
  		return -EOPNOTSUPP;
  	}

@@ -234,6 +238,24 @@ static int tmp421_read_string(struct device *dev, enum hwmon_sensor_types type,
  	return 0;
  }
  
+static int tmp421_write(struct device *dev, enum hwmon_sensor_types type,
+			u32 attr, int channel, long val)
+{
+	struct tmp421_data *data = dev_get_drvdata(dev);
+	int ret;
+
+	switch (attr) {
+	case hwmon_temp_enable:
+		data->channel[channel].enabled = val;
+		ret = tmp421_enable_channels(data);
+		break;
+	default:
+	    ret = -EOPNOTSUPP;
+	}
+
+	return ret;
+}
+
  static umode_t tmp421_is_visible(const void *data, enum hwmon_sensor_types type,
  				 u32 attr, int channel)
  {

@@ -243,6 +265,8 @@ static umode_t tmp421_is_visible(const void *data, enum hwmon_sensor_types type,
  		return 0444;
  	case hwmon_temp_label:
  		return 0444;
+	case hwmon_temp_enable:
+		return 0644;
  	default:
  		return 0;
  	}

@@ -402,6 +426,7 @@ static const struct hwmon_ops tmp421_ops = {
  	.is_visible = tmp421_is_visible,
  	.read = tmp421_read,
  	.read_string = tmp421_read_string,
+	.write = tmp421_write,
  };
  
  static int tmp421_probe(struct i2c_client *client)

@@ -424,7 +449,7 @@ static int tmp421_probe(struct i2c_client *client)
  	data->client = client;
  
  	for (i = 0; i < data->channels; i++) {
-		data->temp_config[i] = HWMON_T_INPUT | HWMON_T_FAULT;
+		data->temp_config[i] = HWMON_T_INPUT | HWMON_T_FAULT | HWMON_T_ENABLE;
  		data->channel[i].enabled = true;
  	}