[RFC][PATCH 3/5] thermal: Add support for setting notification thresholds

[Srinivas Pandruvada]

Add new attributes in thermal syfs when a thermal drivers provides
callbacks for them and CONFIG_THERMAL_USER_EVENT_INTERFACE is defined.

These attribute allow user space to stop polling for temperature.

These attributes are:
- temp_thres_low: Specify a notification temperature for a low
temperature threshold event.
temp_thres_high: Specify a notification temperature for a high
temperature threshold event.
temp_thres_hyst: Specify a change in temperature to send notification
again.

This is implemented by adding additional sysfs attribute group. The
changes in this patch are trivial to add new attributes in thermal
sysfs as done for other attributes.

Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@xxxxxxxxxxxxxxx>
---
 drivers/thermal/thermal_sysfs.c | 136 +++++++++++++++++++++++++++++++-
 include/linux/thermal.h         |  10 ++-
 2 files changed, 143 insertions(+), 3 deletions(-)

diff --git a/drivers/thermal/thermal_sysfs.c b/drivers/thermal/thermal_sysfs.c
index aa99edb4dff7..aa85424c3ac4 100644
--- a/drivers/thermal/thermal_sysfs.c
+++ b/drivers/thermal/thermal_sysfs.c
@@ -215,6 +215,125 @@ trip_point_hyst_show(struct device *dev, struct device_attribute *attr,
 	return ret ? ret : sprintf(buf, "%d\n", temperature);
 }
 
+#if IS_ENABLED(CONFIG_THERMAL_USER_EVENT_INTERFACE)
+
+#define create_thres_attr(name)					\
+	static ssize_t							\
+	name##_show(struct device *dev, struct device_attribute *devattr, \
+		char *buf)						\
+	{								\
+	struct thermal_zone_device *tz = to_thermal_zone(dev);	\
+	int temperature, ret;						\
+									\
+	ret = tz->ops->get_##name(tz, &temperature);			\
+									\
+	return ret ? ret : sprintf(buf, "%d\n", temperature);	\
+	}								\
+									\
+	static ssize_t							\
+	name##_store(struct device *dev, struct device_attribute *devattr, \
+		const char *buf, size_t count)				\
+	{								\
+		struct thermal_zone_device *tz = to_thermal_zone(dev);	\
+		int temperature, ret;					\
+									\
+		if (kstrtoint(buf, 10, &temperature))			\
+			return -EINVAL;				\
+									\
+		ret = tz->ops->set_##name(tz, temperature);		\
+		return ret ? ret : count;				\
+	}
+
+create_thres_attr(temp_thres_low);
+create_thres_attr(temp_thres_high);
+create_thres_attr(temp_thres_hyst);
+
+static int create_user_events_attrs(struct thermal_zone_device *tz)
+{
+	struct attribute **attrs;
+	int index = 0;
+
+	if (tz->ops->get_temp_thres_low)
+		++index;
+	if (tz->ops->get_temp_thres_high)
+		++index;
+	if (tz->ops->get_temp_thres_high)
+		++index;
+
+	/* One additional space for NULL */
+	attrs = kcalloc(index + 1, sizeof(*attrs), GFP_KERNEL);
+	if (!attrs)
+		return -ENOMEM;
+
+	tz->threshold_attrs = kcalloc(index, sizeof(*tz->threshold_attrs), GFP_KERNEL);
+	if (!tz->threshold_attrs) {
+		kfree(attrs);
+		return -ENOMEM;
+	}
+
+	index = 0;
+
+	if (tz->ops->get_temp_thres_low) {
+		snprintf(tz->threshold_attrs[index].name, THERMAL_NAME_LENGTH,
+			 "temp_thres_low");
+
+		sysfs_attr_init(&tz->threshold_attrs[index].attr.attr);
+		tz->threshold_attrs[index].attr.attr.name =
+						tz->threshold_attrs[index].name;
+		tz->threshold_attrs[index].attr.attr.mode = S_IWUSR | S_IRUGO;
+		tz->threshold_attrs[index].attr.show = temp_thres_low_show;
+		tz->threshold_attrs[index].attr.store = temp_thres_low_store;
+		attrs[index] = &tz->threshold_attrs[index].attr.attr;
+		++index;
+	}
+	if (tz->ops->get_temp_thres_high) {
+		snprintf(tz->threshold_attrs[index].name, THERMAL_NAME_LENGTH,
+			 "temp_thres_high");
+
+		sysfs_attr_init(&tz->threshold_attrs[index].attr.attr);
+		tz->threshold_attrs[index].attr.attr.name =
+						tz->threshold_attrs[index].name;
+		tz->threshold_attrs[index].attr.attr.mode = S_IWUSR | S_IRUGO;
+		tz->threshold_attrs[index].attr.show = temp_thres_high_show;
+		tz->threshold_attrs[index].attr.store = temp_thres_high_store;
+		attrs[index] = &tz->threshold_attrs[index].attr.attr;
+		++index;
+	}
+	if (tz->ops->get_temp_thres_hyst) {
+		snprintf(tz->threshold_attrs[index].name, THERMAL_NAME_LENGTH,
+			 "temp_thres_hyst");
+
+		sysfs_attr_init(&tz->threshold_attrs[index].attr.attr);
+		tz->threshold_attrs[index].attr.attr.name =
+						tz->threshold_attrs[index].name;
+		tz->threshold_attrs[index].attr.attr.mode = S_IWUSR | S_IRUGO;
+		tz->threshold_attrs[index].attr.show = temp_thres_hyst_show;
+		tz->threshold_attrs[index].attr.store = temp_thres_hyst_store;
+		attrs[index] = &tz->threshold_attrs[index].attr.attr;
+		++index;
+	}
+	attrs[index] = NULL;
+	tz->threshold_attribute_group.attrs = attrs;
+
+	return 0;
+}
+
+static void delete_user_events_attrs(struct thermal_zone_device *tz)
+{
+	kfree(tz->threshold_attrs);
+	kfree(tz->threshold_attribute_group.attrs);
+}
+#else
+static int create_user_events_attrs(struct thermal_zone_device *tz)
+{
+	return -EINVAL;
+}
+
+static void delete_user_events_attrs(struct thermal_zone_device *tz)
+{
+}
+#endif
+
 static ssize_t
 passive_store(struct device *dev, struct device_attribute *attr,
 	      const char *buf, size_t count)
@@ -625,16 +744,27 @@ int thermal_zone_create_device_groups(struct thermal_zone_device *tz,
 {
 	const struct attribute_group **groups;
 	int i, size, result;
+	int start = 0;
 
 	/* we need one extra for trips and the NULL to terminate the array */
 	size = ARRAY_SIZE(thermal_zone_attribute_groups) + 2;
+
+	result = create_user_events_attrs(tz);
+	if (!result) {
+		++size;
+		++start;
+	}
+
 	/* This also takes care of API requirement to be NULL terminated */
 	groups = kcalloc(size, sizeof(*groups), GFP_KERNEL);
 	if (!groups)
 		return -ENOMEM;
 
-	for (i = 0; i < size - 2; i++)
-		groups[i] = thermal_zone_attribute_groups[i];
+	if (start)
+		groups[0] = &tz->threshold_attribute_group;
+
+	for (i = 0; i < size - 2 - start; i++)
+		groups[i + start] = thermal_zone_attribute_groups[i];
 
 	if (tz->trips) {
 		result = create_trip_attrs(tz, mask);
@@ -660,6 +790,8 @@ void thermal_zone_destroy_device_groups(struct thermal_zone_device *tz)
 	if (tz->trips)
 		destroy_trip_attrs(tz);
 
+	delete_user_events_attrs(tz);
+
 	kfree(tz->device.groups);
 }
 
diff --git a/include/linux/thermal.h b/include/linux/thermal.h
index f5e1e7c6a9a2..ee9d79ace7ce 100644
--- a/include/linux/thermal.h
+++ b/include/linux/thermal.h
@@ -102,6 +102,12 @@ struct thermal_zone_device_ops {
 			  enum thermal_trend *);
 	int (*notify) (struct thermal_zone_device *, int,
 		       enum thermal_trip_type);
+	int (*set_temp_thres_low)(struct thermal_zone_device *, int);
+	int (*set_temp_thres_high)(struct thermal_zone_device *, int);
+	int (*set_temp_thres_hyst)(struct thermal_zone_device *, int);
+	int (*get_temp_thres_low)(struct thermal_zone_device *, int *);
+	int (*get_temp_thres_high)(struct thermal_zone_device *, int *);
+	int (*get_temp_thres_hyst)(struct thermal_zone_device *, int *);
 };
 
 struct thermal_cooling_device_ops {
@@ -208,6 +214,8 @@ struct thermal_zone_device {
 	struct list_head node;
 	struct delayed_work poll_queue;
 	enum thermal_notify_event notify_event;
+	struct attribute_group threshold_attribute_group;
+	struct thermal_attr *threshold_attrs;
 };
 
 /**
@@ -558,7 +566,7 @@ enum thermal_device_events {
 	THERMAL_PERF_CHANGED,
 };
 
-#ifdef CONFIG_THERMAL_USER_EVENT_INTERFACE
+#if IS_ENABLED(CONFIG_THERMAL_USER_EVENT_INTERFACE)
 int thermal_dev_send_event(int zone_id, enum thermal_device_events event, u64 event_data);
 #else
 int thermal_dev_send_event(int zone_id, enum thermal_device_events event, u64 event_data)
-- 
2.25.4