hwmon: (applesmc) Add temperature sensor labels to sysfs interface

The Apple SMC uses a systematic labeling scheme for the hardware
temperature sensors. This scheme is currently hidden from
userland. Since the sensor set, and consequently the numbering,
differs between models, an extensive database of configurations is
required for an application such as fan control. This patch adds the
SMC labels to the hwmon sysfs interface, allowing applications to use
the sensors more intelligibly.

[rydberg@euromail.se: fixed error handling]
Signed-off-by: Alex Murray <murray.alex@gmail.com>
Signed-off-by: Henrik Rydberg <rydberg@euromail.se>
Signed-off-by: Jean Delvare <khali@linux-fr.org>

drivers/hwmon/applesmc.c

@@ -660,6 +660,17 @@ static ssize_t applesmc_light_show(struct device *dev,
 		return snprintf(sysfsbuf, PAGE_SIZE, "(%d,%d)\n", left, right);
 }
 
+/* Displays sensor key as label */
+static ssize_t applesmc_show_sensor_label(struct device *dev,
+			struct device_attribute *devattr, char *sysfsbuf)
+{
+	struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);
+	const char *key =
+		temperature_sensors_sets[applesmc_temperature_set][attr->index];
+
+	return snprintf(sysfsbuf, PAGE_SIZE, "%s\n", key);
+}
+
 /* Displays degree Celsius * 1000 */
 static ssize_t applesmc_show_temperature(struct device *dev,
 			struct device_attribute *devattr, char *sysfsbuf)
@@ -1127,6 +1138,86 @@ static const struct attribute_group fan_attribute_groups[] = {
 /*
  * Temperature sensors sysfs entries.
  */
+static SENSOR_DEVICE_ATTR(temp1_label, S_IRUGO,
+					applesmc_show_sensor_label, NULL, 0);
+static SENSOR_DEVICE_ATTR(temp2_label, S_IRUGO,
+					applesmc_show_sensor_label, NULL, 1);
+static SENSOR_DEVICE_ATTR(temp3_label, S_IRUGO,
+					applesmc_show_sensor_label, NULL, 2);
+static SENSOR_DEVICE_ATTR(temp4_label, S_IRUGO,
+					applesmc_show_sensor_label, NULL, 3);
+static SENSOR_DEVICE_ATTR(temp5_label, S_IRUGO,
+					applesmc_show_sensor_label, NULL, 4);
+static SENSOR_DEVICE_ATTR(temp6_label, S_IRUGO,
+					applesmc_show_sensor_label, NULL, 5);
+static SENSOR_DEVICE_ATTR(temp7_label, S_IRUGO,
+					applesmc_show_sensor_label, NULL, 6);
+static SENSOR_DEVICE_ATTR(temp8_label, S_IRUGO,
+					applesmc_show_sensor_label, NULL, 7);
+static SENSOR_DEVICE_ATTR(temp9_label, S_IRUGO,
+					applesmc_show_sensor_label, NULL, 8);
+static SENSOR_DEVICE_ATTR(temp10_label, S_IRUGO,
+					applesmc_show_sensor_label, NULL, 9);
+static SENSOR_DEVICE_ATTR(temp11_label, S_IRUGO,
+					applesmc_show_sensor_label, NULL, 10);
+static SENSOR_DEVICE_ATTR(temp12_label, S_IRUGO,
+					applesmc_show_sensor_label, NULL, 11);
+static SENSOR_DEVICE_ATTR(temp13_label, S_IRUGO,
+					applesmc_show_sensor_label, NULL, 12);
+static SENSOR_DEVICE_ATTR(temp14_label, S_IRUGO,
+					applesmc_show_sensor_label, NULL, 13);
+static SENSOR_DEVICE_ATTR(temp15_label, S_IRUGO,
+					applesmc_show_sensor_label, NULL, 14);
+static SENSOR_DEVICE_ATTR(temp16_label, S_IRUGO,
+					applesmc_show_sensor_label, NULL, 15);
+static SENSOR_DEVICE_ATTR(temp17_label, S_IRUGO,
+					applesmc_show_sensor_label, NULL, 16);
+static SENSOR_DEVICE_ATTR(temp18_label, S_IRUGO,
+					applesmc_show_sensor_label, NULL, 17);
+static SENSOR_DEVICE_ATTR(temp19_label, S_IRUGO,
+					applesmc_show_sensor_label, NULL, 18);
+static SENSOR_DEVICE_ATTR(temp20_label, S_IRUGO,
+					applesmc_show_sensor_label, NULL, 19);
+static SENSOR_DEVICE_ATTR(temp21_label, S_IRUGO,
+					applesmc_show_sensor_label, NULL, 20);
+static SENSOR_DEVICE_ATTR(temp22_label, S_IRUGO,
+					applesmc_show_sensor_label, NULL, 21);
+static SENSOR_DEVICE_ATTR(temp23_label, S_IRUGO,
+					applesmc_show_sensor_label, NULL, 22);
+static SENSOR_DEVICE_ATTR(temp24_label, S_IRUGO,
+					applesmc_show_sensor_label, NULL, 23);
+static SENSOR_DEVICE_ATTR(temp25_label, S_IRUGO,
+					applesmc_show_sensor_label, NULL, 24);
+static SENSOR_DEVICE_ATTR(temp26_label, S_IRUGO,
+					applesmc_show_sensor_label, NULL, 25);
+static SENSOR_DEVICE_ATTR(temp27_label, S_IRUGO,
+					applesmc_show_sensor_label, NULL, 26);
+static SENSOR_DEVICE_ATTR(temp28_label, S_IRUGO,
+					applesmc_show_sensor_label, NULL, 27);
+static SENSOR_DEVICE_ATTR(temp29_label, S_IRUGO,
+					applesmc_show_sensor_label, NULL, 28);
+static SENSOR_DEVICE_ATTR(temp30_label, S_IRUGO,
+					applesmc_show_sensor_label, NULL, 29);
+static SENSOR_DEVICE_ATTR(temp31_label, S_IRUGO,
+					applesmc_show_sensor_label, NULL, 30);
+static SENSOR_DEVICE_ATTR(temp32_label, S_IRUGO,
+					applesmc_show_sensor_label, NULL, 31);
+static SENSOR_DEVICE_ATTR(temp33_label, S_IRUGO,
+					applesmc_show_sensor_label, NULL, 32);
+static SENSOR_DEVICE_ATTR(temp34_label, S_IRUGO,
+					applesmc_show_sensor_label, NULL, 33);
+static SENSOR_DEVICE_ATTR(temp35_label, S_IRUGO,
+					applesmc_show_sensor_label, NULL, 34);
+static SENSOR_DEVICE_ATTR(temp36_label, S_IRUGO,
+					applesmc_show_sensor_label, NULL, 35);
+static SENSOR_DEVICE_ATTR(temp37_label, S_IRUGO,
+					applesmc_show_sensor_label, NULL, 36);
+static SENSOR_DEVICE_ATTR(temp38_label, S_IRUGO,
+					applesmc_show_sensor_label, NULL, 37);
+static SENSOR_DEVICE_ATTR(temp39_label, S_IRUGO,
+					applesmc_show_sensor_label, NULL, 38);
+static SENSOR_DEVICE_ATTR(temp40_label, S_IRUGO,
+					applesmc_show_sensor_label, NULL, 39);
 static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO,
 					applesmc_show_temperature, NULL, 0);
 static SENSOR_DEVICE_ATTR(temp2_input, S_IRUGO,
@@ -1208,6 +1299,50 @@ static SENSOR_DEVICE_ATTR(temp39_input, S_IRUGO,
 static SENSOR_DEVICE_ATTR(temp40_input, S_IRUGO,
 					applesmc_show_temperature, NULL, 39);
 
+static struct attribute *label_attributes[] = {
+	&sensor_dev_attr_temp1_label.dev_attr.attr,
+	&sensor_dev_attr_temp2_label.dev_attr.attr,
+	&sensor_dev_attr_temp3_label.dev_attr.attr,
+	&sensor_dev_attr_temp4_label.dev_attr.attr,
+	&sensor_dev_attr_temp5_label.dev_attr.attr,
+	&sensor_dev_attr_temp6_label.dev_attr.attr,
+	&sensor_dev_attr_temp7_label.dev_attr.attr,
+	&sensor_dev_attr_temp8_label.dev_attr.attr,
+	&sensor_dev_attr_temp9_label.dev_attr.attr,
+	&sensor_dev_attr_temp10_label.dev_attr.attr,
+	&sensor_dev_attr_temp11_label.dev_attr.attr,
+	&sensor_dev_attr_temp12_label.dev_attr.attr,
+	&sensor_dev_attr_temp13_label.dev_attr.attr,
+	&sensor_dev_attr_temp14_label.dev_attr.attr,
+	&sensor_dev_attr_temp15_label.dev_attr.attr,
+	&sensor_dev_attr_temp16_label.dev_attr.attr,
+	&sensor_dev_attr_temp17_label.dev_attr.attr,
+	&sensor_dev_attr_temp18_label.dev_attr.attr,
+	&sensor_dev_attr_temp19_label.dev_attr.attr,
+	&sensor_dev_attr_temp20_label.dev_attr.attr,
+	&sensor_dev_attr_temp21_label.dev_attr.attr,
+	&sensor_dev_attr_temp22_label.dev_attr.attr,
+	&sensor_dev_attr_temp23_label.dev_attr.attr,
+	&sensor_dev_attr_temp24_label.dev_attr.attr,
+	&sensor_dev_attr_temp25_label.dev_attr.attr,
+	&sensor_dev_attr_temp26_label.dev_attr.attr,
+	&sensor_dev_attr_temp27_label.dev_attr.attr,
+	&sensor_dev_attr_temp28_label.dev_attr.attr,
+	&sensor_dev_attr_temp29_label.dev_attr.attr,
+	&sensor_dev_attr_temp30_label.dev_attr.attr,
+	&sensor_dev_attr_temp31_label.dev_attr.attr,
+	&sensor_dev_attr_temp32_label.dev_attr.attr,
+	&sensor_dev_attr_temp33_label.dev_attr.attr,
+	&sensor_dev_attr_temp34_label.dev_attr.attr,
+	&sensor_dev_attr_temp35_label.dev_attr.attr,
+	&sensor_dev_attr_temp36_label.dev_attr.attr,
+	&sensor_dev_attr_temp37_label.dev_attr.attr,
+	&sensor_dev_attr_temp38_label.dev_attr.attr,
+	&sensor_dev_attr_temp39_label.dev_attr.attr,
+	&sensor_dev_attr_temp40_label.dev_attr.attr,
+	NULL
+};
+
 static struct attribute *temperature_attributes[] = {
 	&sensor_dev_attr_temp1_input.dev_attr.attr,
 	&sensor_dev_attr_temp2_input.dev_attr.attr,
@@ -1255,6 +1390,10 @@ static struct attribute *temperature_attributes[] = {
 static const struct attribute_group temperature_attributes_group =
 	{ .attrs = temperature_attributes };
 
+static const struct attribute_group label_attributes_group = {
+	.attrs = label_attributes
+};
+
 /* Module stuff */
 
 /*
@@ -1556,7 +1695,8 @@ static int __init applesmc_init(void)
 	for (i = 0;
 	     temperature_sensors_sets[applesmc_temperature_set][i] != NULL;
 	     i++) {
-		if (temperature_attributes[i] == NULL) {
+		if (temperature_attributes[i] == NULL ||
+		    label_attributes[i] == NULL) {
 			printk(KERN_ERR "applesmc: More temperature sensors "
 				"in temperature_sensors_sets (at least %i)"
 				"than available sysfs files in "
@@ -1568,6 +1708,10 @@ static int __init applesmc_init(void)
 						temperature_attributes[i]);
 		if (ret)
 			goto out_temperature;
+		ret = sysfs_create_file(&pdev->dev.kobj,
+						label_attributes[i]);
+		if (ret)
+			goto out_temperature;
 	}
 
 	if (applesmc_accelerometer) {
@@ -1618,6 +1762,7 @@ static int __init applesmc_init(void)
 	if (applesmc_accelerometer)
 		applesmc_release_accelerometer();
 out_temperature:
+	sysfs_remove_group(&pdev->dev.kobj, &label_attributes_group);
 	sysfs_remove_group(&pdev->dev.kobj, &temperature_attributes_group);
 out_fans:
 	while (fans_handled)
@@ -1647,6 +1792,7 @@ static void __exit applesmc_exit(void)
 	}
 	if (applesmc_accelerometer)
 		applesmc_release_accelerometer();
+	sysfs_remove_group(&pdev->dev.kobj, &label_attributes_group);
 	sysfs_remove_group(&pdev->dev.kobj, &temperature_attributes_group);
 	while (fans_handled)
 		sysfs_remove_group(&pdev->dev.kobj,