[PATCH v2 2/3] thermal: Add support of multi sensors to thermal_core

[Alexandre Bailon <abailon@baylibre.com>]

This adds support of multi sensors to thermal.
Currently, this only support the get_temp operation.
This returns an average temperature of all the sensors.
If defined, a coefficient is applied to the value read from the sensor
before computing the average.

Signed-off-by: Alexandre Bailon <abailon@baylibre.com>
---
 drivers/thermal/Makefile        |   1 +
 drivers/thermal/thermal_core.h  |   7 ++
 drivers/thermal/thermal_multi.c | 178 ++++++++++++++++++++++++++++++++
 3 files changed, 186 insertions(+)
 create mode 100644 drivers/thermal/thermal_multi.c

diff --git a/drivers/thermal/Makefile b/drivers/thermal/Makefile
index c934cab309ae..757289a406f7 100644
--- a/drivers/thermal/Makefile
+++ b/drivers/thermal/Makefile
@@ -6,6 +6,7 @@ CFLAGS_thermal_core.o		:= -I$(src)
 obj-$(CONFIG_THERMAL)		+= thermal_sys.o
 thermal_sys-y			+= thermal_core.o thermal_sysfs.o
 thermal_sys-y			+= thermal_trip.o thermal_helpers.o
+thermal_sys-y			+= thermal_multi.o
 
 # netlink interface to manage the thermal framework
 thermal_sys-$(CONFIG_THERMAL_NETLINK)		+= thermal_netlink.o
diff --git a/drivers/thermal/thermal_core.h b/drivers/thermal/thermal_core.h
index 0a3b3ec5120b..26e83a5c8298 100644
--- a/drivers/thermal/thermal_core.h
+++ b/drivers/thermal/thermal_core.h
@@ -138,6 +138,13 @@ ssize_t weight_show(struct device *, struct device_attribute *, char *);
 ssize_t weight_store(struct device *, struct device_attribute *, const char *,
 		     size_t);
 
+/* Multi sensors */
+int thermal_multi_sensor_validate_coeff(int *coeff, int count, int offset);
+int thermal_multi_sensor_register(const char *name,
+	struct thermal_zone_device *sensor_tz, int coeff);
+void thermal_multi_sensor_unregister(struct thermal_zone_device *sensor_tz);
+
+
 #ifdef CONFIG_THERMAL_STATISTICS
 void thermal_cooling_device_stats_update(struct thermal_cooling_device *cdev,
 					 unsigned long new_state);
diff --git a/drivers/thermal/thermal_multi.c b/drivers/thermal/thermal_multi.c
new file mode 100644
index 000000000000..a5a4f1f2d594
--- /dev/null
+++ b/drivers/thermal/thermal_multi.c
@@ -0,0 +1,178 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/err.h>
+#include <linux/export.h>
+#include <linux/of.h>
+#include <linux/slab.h>
+#include <linux/thermal.h>
+#include <linux/types.h>
+#include <linux/string.h>
+
+#include "thermal_core.h"
+
+struct sensor_interface {
+	struct thermal_zone_device *tz;
+	int coeff;
+
+	struct list_head node;
+};
+
+struct multi_sensor_thermal_zone {
+	struct thermal_zone_device *tz;
+	struct mutex sensors_lock;
+	struct list_head sensors;
+
+	struct list_head node;
+};
+
+static DEFINE_MUTEX(multi_tz_mutex);
+static LIST_HEAD(multi_tz_list);
+
+#define TJ_MAX 120000
+
+static int multi_sensor_get_temp(struct thermal_zone_device *tz, int *temp)
+{
+	struct multi_sensor_thermal_zone *multi_tz = tz->devdata;
+	struct sensor_interface *sensor;
+	int accumulated_temp = 0;
+	u32 accumulated_coeff;
+	int ret;
+
+	mutex_lock(&multi_tz->sensors_lock);
+
+	if (list_empty(&multi_tz->sensors)) {
+		mutex_unlock(&multi_tz->sensors_lock);
+		return -ENODEV;
+	}
+
+	list_for_each_entry(sensor, &multi_tz->sensors, node) {
+		ret = thermal_zone_get_temp(sensor->tz, temp);
+		if (ret) {
+			mutex_unlock(&multi_tz->sensors_lock);
+			return ret;
+		}
+
+		accumulated_temp += *temp * sensor->coeff;
+		accumulated_coeff += sensor->coeff;
+	}
+
+	mutex_unlock(&multi_tz->sensors_lock);
+
+	*temp = accumulated_temp / accumulated_coeff;
+	return ret;
+}
+
+struct thermal_zone_device_ops multi_sensor_ops = {
+	.get_temp = multi_sensor_get_temp,
+};
+
+int thermal_multi_sensor_validate_coeff(int *coeff, int count, int offset)
+{
+	int max_accumulated_temp = 0;
+	int i;
+
+	for (i = 0; i < count; i++) {
+		max_accumulated_temp += TJ_MAX * coeff[i];
+		if (max_accumulated_temp < 0)
+			return -EOVERFLOW;
+	}
+
+	max_accumulated_temp += offset;
+	return max_accumulated_temp < 0 ? -EOVERFLOW : 0;
+}
+
+static struct thermal_zone_device *multi_sensor_tz_alloc(const char *name)
+{
+	struct thermal_zone_device *tz;
+	struct thermal_zone_params tzp = {};
+	struct multi_sensor_thermal_zone *multi_tz;
+
+	tz = thermal_zone_get_zone_by_name(name);
+	if (!IS_ERR(tz)) {
+		mutex_unlock(&multi_tz_mutex);
+		return tz;
+	}
+
+	multi_tz = kzalloc(sizeof(*multi_tz), GFP_KERNEL);
+	if (!multi_tz)
+		return ERR_PTR(-ENOMEM);
+	mutex_init(&multi_tz->sensors_lock);
+	INIT_LIST_HEAD(&multi_tz->sensors);
+
+	tzp.no_hwmon = true;
+	tzp.slope = 1;
+	tzp.offset = 0;
+
+	tz = thermal_tripless_zone_device_register(name, multi_tz,
+						   &multi_sensor_ops, &tzp);
+	if (IS_ERR(tz)) {
+		kfree(multi_tz);
+	} else {
+		multi_tz->tz = tz;
+		list_add(&multi_tz->node, &multi_tz_list);
+	}
+
+	return tz;
+}
+
+int thermal_multi_sensor_register(const char *name,
+	struct thermal_zone_device *sensor_tz, int coeff)
+{
+	struct thermal_zone_device *tz;
+	struct multi_sensor_thermal_zone *multi_tz;
+	struct sensor_interface *sensor;
+
+	mutex_lock(&multi_tz_mutex);
+
+	tz = multi_sensor_tz_alloc(name);
+	if (IS_ERR(tz)) {
+		mutex_unlock(&multi_tz_mutex);
+		return PTR_ERR(tz);
+	}
+	multi_tz =  tz->devdata;
+
+	sensor = kzalloc(sizeof(*sensor), GFP_KERNEL);
+	if (!sensor) {
+		mutex_unlock(&multi_tz_mutex);
+		return -ENOMEM;
+	}
+
+	sensor->tz = sensor_tz;
+	sensor->coeff = coeff;
+	mutex_lock(&multi_tz->sensors_lock);
+	list_add(&sensor->node, &multi_tz->sensors);
+	mutex_unlock(&multi_tz->sensors_lock);
+
+	thermal_zone_device_enable(tz);
+
+	mutex_unlock(&multi_tz_mutex);
+
+	return 0;
+}
+
+void thermal_multi_sensor_unregister(struct thermal_zone_device *sensor_tz)
+{
+	struct multi_sensor_thermal_zone *multi_tz;
+	struct sensor_interface *sensor, *tmp;
+
+	mutex_lock(&multi_tz_mutex);
+	list_for_each_entry(multi_tz, &multi_tz_list, node) {
+		mutex_lock(&multi_tz->sensors_lock);
+		list_for_each_entry_safe(sensor, tmp, &multi_tz->sensors, node) {
+			if (sensor->tz == sensor_tz) {
+				list_del(&sensor->node);
+				kfree(sensor);
+				break;
+			}
+		}
+
+		if (list_empty(&multi_tz->sensors)) {
+			thermal_zone_device_unregister(multi_tz->tz);
+			mutex_unlock(&multi_tz->sensors_lock);
+			kfree(multi_tz);
+		} else {
+			mutex_unlock(&multi_tz->sensors_lock);
+		}
+	}
+	mutex_unlock(&multi_tz_mutex);
+}
-- 
2.41.0