hwmon: (max1668) Add support for tempX_fault attributes

MAX1668 and compatibles have several external temperature sensors, but only a
single FAULT status bit. If a fault occurs, the temperature reported on the
affected sensors is 127 degrees C. Use this knowledge to report fault on
external sensors.

Signed-off-by: Guenter Roeck <guenter.roeck@ericsson.com>
Acked-by: Jean Delvare <khali@linux-fr.org>

drivers/hwmon/max1668.c

@@ -122,16 +122,14 @@ static struct max1668_data *max1668_update_device(struct device *dev)
 		ret = ERR_PTR(val);
 		goto abort;
 	}
-	data->alarms &= 0x00ff;
-	data->alarms |= ((u8) (val & 0x60)) << 8;
+	data->alarms = val << 8;
 
 	val = i2c_smbus_read_byte_data(client, MAX1668_REG_STAT2);
 	if (unlikely(val < 0)) {
 		ret = ERR_PTR(val);
 		goto abort;
 	}
-	data->alarms &= 0xff00;
-	data->alarms |= ((u8) val);
+	data->alarms |= val;
 
 	data->last_updated = jiffies;
 	data->valid = 1;
@@ -189,6 +187,19 @@ static ssize_t show_alarm(struct device *dev, struct device_attribute *attr,
 	return sprintf(buf, "%u\n", (data->alarms >> index) & 0x1);
 }
 
+static ssize_t show_fault(struct device *dev,
+			  struct device_attribute *devattr, char *buf)
+{
+	int index = to_sensor_dev_attr(devattr)->index;
+	struct max1668_data *data = max1668_update_device(dev);
+
+	if (IS_ERR(data))
+		return PTR_ERR(data);
+
+	return sprintf(buf, "%u\n",
+		       (data->alarms & (1 << 12)) && data->temp[index] == 127);
+}
+
 static ssize_t set_temp_max(struct device *dev,
 			    struct device_attribute *devattr,
 			    const char *buf, size_t count)
@@ -276,6 +287,11 @@ static SENSOR_DEVICE_ATTR(temp4_max_alarm, S_IRUGO, show_alarm, NULL, 2);
 static SENSOR_DEVICE_ATTR(temp5_min_alarm, S_IRUGO, show_alarm, NULL, 1);
 static SENSOR_DEVICE_ATTR(temp5_max_alarm, S_IRUGO, show_alarm, NULL, 0);
 
+static SENSOR_DEVICE_ATTR(temp2_fault, S_IRUGO, show_fault, NULL, 1);
+static SENSOR_DEVICE_ATTR(temp3_fault, S_IRUGO, show_fault, NULL, 2);
+static SENSOR_DEVICE_ATTR(temp4_fault, S_IRUGO, show_fault, NULL, 3);
+static SENSOR_DEVICE_ATTR(temp5_fault, S_IRUGO, show_fault, NULL, 4);
+
 /* Attributes common to MAX1668, MAX1989 and MAX1805 */
 static struct attribute *max1668_attribute_common[] = {
 	&sensor_dev_attr_temp1_max.dev_attr.attr,
@@ -294,6 +310,9 @@ static struct attribute *max1668_attribute_common[] = {
 	&sensor_dev_attr_temp2_min_alarm.dev_attr.attr,
 	&sensor_dev_attr_temp3_max_alarm.dev_attr.attr,
 	&sensor_dev_attr_temp3_min_alarm.dev_attr.attr,
+
+	&sensor_dev_attr_temp2_fault.dev_attr.attr,
+	&sensor_dev_attr_temp3_fault.dev_attr.attr,
 	NULL
 };
 
@@ -310,6 +329,9 @@ static struct attribute *max1668_attribute_unique[] = {
 	&sensor_dev_attr_temp4_min_alarm.dev_attr.attr,
 	&sensor_dev_attr_temp5_max_alarm.dev_attr.attr,
 	&sensor_dev_attr_temp5_min_alarm.dev_attr.attr,
+
+	&sensor_dev_attr_temp4_fault.dev_attr.attr,
+	&sensor_dev_attr_temp5_fault.dev_attr.attr,
 	NULL
 };