thermal: sysfs: Get to trips via attribute pointers

The  _store() and _show() functions for sysfs attributes corresponding
to trip point parameters (type, temperature and hysteresis) read the
trip ID from the attribute name and then use the trip ID as the index
in the given thermal zone's trips table to get to the trip object they
want.

Instead of doing this, make them use the attribute pointer they get
as the second argument to get to the trip object embedded in the same
struct thermal_trip_desc as the struct device_attribute pointed to by
it, which is much more straightforward and less overhead.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Link: https://patch.msgid.link/114841552.nniJfEyVGO@rjwysocki.net

drivers/thermal/thermal_sysfs.c

@@ -12,6 +12,7 @@
 
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 
+#include <linux/container_of.h>
 #include <linux/sysfs.h>
 #include <linux/device.h>
 #include <linux/err.h>
@@ -78,39 +79,38 @@ mode_store(struct device *dev, struct device_attribute *attr,
 	return count;
 }
 
+#define thermal_trip_of_attr(_ptr_, _attr_)				\
+	({ 								\
+		struct thermal_trip_desc *td;				\
+									\
+		td = container_of(_ptr_, struct thermal_trip_desc,	\
+				  trip_attrs._attr_.attr);		\
+		&td->trip;						\
+	})
+
 static ssize_t
 trip_point_type_show(struct device *dev, struct device_attribute *attr,
 		     char *buf)
 {
-	struct thermal_zone_device *tz = to_thermal_zone(dev);
-	int trip_id;
-
-	if (sscanf(attr->attr.name, "trip_point_%d_type", &trip_id) != 1)
-		return -EINVAL;
+	struct thermal_trip *trip = thermal_trip_of_attr(attr, type);
 
-	return sprintf(buf, "%s\n", thermal_trip_type_name(tz->trips[trip_id].trip.type));
+	return sprintf(buf, "%s\n", thermal_trip_type_name(trip->type));
 }
 
 static ssize_t
 trip_point_temp_store(struct device *dev, struct device_attribute *attr,
 		      const char *buf, size_t count)
 {
+	struct thermal_trip *trip = thermal_trip_of_attr(attr, temp);
 	struct thermal_zone_device *tz = to_thermal_zone(dev);
-	struct thermal_trip *trip;
-	int trip_id, ret;
-	int temp;
+	int ret, temp;
 
 	ret = kstrtoint(buf, 10, &temp);
 	if (ret)
 		return -EINVAL;
 
-	if (sscanf(attr->attr.name, "trip_point_%d_temp", &trip_id) != 1)
-		return -EINVAL;
-
 	mutex_lock(&tz->lock);
 
-	trip = &tz->trips[trip_id].trip;
-
 	if (temp != trip->temperature) {
 		if (tz->ops.set_trip_temp) {
 			ret = tz->ops.set_trip_temp(tz, trip, temp);
@@ -133,35 +133,25 @@ static ssize_t
 trip_point_temp_show(struct device *dev, struct device_attribute *attr,
 		     char *buf)
 {
-	struct thermal_zone_device *tz = to_thermal_zone(dev);
-	int trip_id;
+	struct thermal_trip *trip = thermal_trip_of_attr(attr, temp);
 
-	if (sscanf(attr->attr.name, "trip_point_%d_temp", &trip_id) != 1)
-		return -EINVAL;
-
-	return sprintf(buf, "%d\n", READ_ONCE(tz->trips[trip_id].trip.temperature));
+	return sprintf(buf, "%d\n", READ_ONCE(trip->temperature));
 }
 
 static ssize_t
 trip_point_hyst_store(struct device *dev, struct device_attribute *attr,
 		      const char *buf, size_t count)
 {
+	struct thermal_trip *trip = thermal_trip_of_attr(attr, hyst);
 	struct thermal_zone_device *tz = to_thermal_zone(dev);
-	struct thermal_trip *trip;
-	int trip_id, ret;
-	int hyst;
+	int ret, hyst;
 
 	ret = kstrtoint(buf, 10, &hyst);
 	if (ret || hyst < 0)
 		return -EINVAL;
 
-	if (sscanf(attr->attr.name, "trip_point_%d_hyst", &trip_id) != 1)
-		return -EINVAL;
-
 	mutex_lock(&tz->lock);
 
-	trip = &tz->trips[trip_id].trip;
-
 	if (hyst != trip->hysteresis) {
 		WRITE_ONCE(trip->hysteresis, hyst);
 
@@ -177,13 +167,9 @@ static ssize_t
 trip_point_hyst_show(struct device *dev, struct device_attribute *attr,
 		     char *buf)
 {
-	struct thermal_zone_device *tz = to_thermal_zone(dev);
-	int trip_id;
-
-	if (sscanf(attr->attr.name, "trip_point_%d_hyst", &trip_id) != 1)
-		return -EINVAL;
+	struct thermal_trip *trip = thermal_trip_of_attr(attr, hyst);
 
-	return sprintf(buf, "%d\n", READ_ONCE(tz->trips[trip_id].trip.hysteresis));
+	return sprintf(buf, "%d\n", READ_ONCE(trip->hysteresis));
 }
 
 static ssize_t