4 files changed, 707 insertions, 0 deletions
diff --git a/drivers/thermal/testing/Makefile b/drivers/thermal/testing/Makefile
new file mode 100644
index 000000000000..ede9678efbce
--- /dev/null
+++ b/drivers/thermal/testing/Makefile
@@ -0,0 +1,7 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# Thermal core testing facility.
+
+obj-$(CONFIG_THERMAL_CORE_TESTING) += thermal-testing.o
+
+thermal-testing-y := command.o zone.o
diff --git a/drivers/thermal/testing/command.c b/drivers/thermal/testing/command.c
new file mode 100644
index 000000000000..ba11d70e8021
--- /dev/null
+++ b/drivers/thermal/testing/command.c
@@ -0,0 +1,221 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright 2024, Intel Corporation
+ *
+ * Author: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
+ *
+ * Thermal subsystem testing facility.
+ *
+ * This facility allows the thermal core functionality to be exercised in a
+ * controlled way in order to verify its behavior.
+ *
+ * It resides in the "thermal-testing" directory under the debugfs root and
+ * starts with a single file called "command" which can be written a string
+ * representing a thermal testing facility command.
+ *
+ * The currently supported commands are listed in the tt_commands enum below.
+ *
+ * The "addtz" command causes a new test thermal zone template to be created,
+ * for example:
+ *
+ * # echo addtz > /sys/kernel/debug/thermal-testing/command
+ *
+ * That template will be represented as a subdirectory in the "thermal-testing"
+ * directory, for example
+ *
+ * # ls /sys/kernel/debug/thermal-testing/
+ * command tz0
+ *
+ * The thermal zone template can be populated with trip points with the help of
+ * the "tzaddtrip" command, for example:
+ *
+ * # echo tzaddtrip:0 > /sys/kernel/debug/thermal-testing/command
+ *
+ * which causes a trip point template to be added to the test thermal zone
+ * template 0 (represented by the tz0 subdirectory in "thermal-testing").
+ *
+ * # ls /sys/kernel/debug/thermal-testing/tz0
+ * init_temp temp trip_0_temp trip_0_hyst
+ *
+ * The temperature of a trip point template is initially THERMAL_TEMP_INVALID
+ * and its hysteresis is initially 0.  They can be adjusted by writing to the
+ * "trip_x_temp" and "trip_x_hyst" files correspoinding to that trip point
+ * template, respectively.
+ *
+ * The initial temperature of a thermal zone based on a template can be set by
+ * writing to the "init_temp" file in its directory under "thermal-testing", for
+ * example:
+ *
+ * echo 50000 > /sys/kernel/debug/thermal-testing/tz0/init_temp
+ *
+ * When ready, "tzreg" command can be used for registering and enabling a
+ * thermal zone based on a given template with the thermal core, for example
+ *
+ * # echo tzreg:0 > /sys/kernel/debug/thermal-testing/command
+ *
+ * In this case, test thermal zone template 0 is used for registering a new
+ * thermal zone and the set of trip point templates associated with it is used
+ * for populating the new thermal zone's trip points table.  The type of the new
+ * thermal zone is "test_tz".
+ *
+ * The temperature and hysteresis of all of the trip points in that new thermal
+ * zone are adjustable via sysfs, so they can be updated at any time.
+ *
+ * The current temperature of the new thermal zone can be set by writing to the
+ * "temp" file in the corresponding thermal zone template's directory under
+ * "thermal-testing", for example
+ *
+ * echo 10000 > /sys/kernel/debug/thermal-testing/tz0/temp
+ *
+ * which will also trigger a temperature update for this zone in the thermal
+ * core, including checking its trip points, sending notifications to user space
+ * if any of them have been crossed and so on.
+ *
+ * When it is not needed any more, a test thermal zone template can be deleted
+ * with the help of the "deltz" command, for example
+ *
+ * # echo deltz:0 > /sys/kernel/debug/thermal-testing/command
+ *
+ * which will also unregister the thermal zone based on it, if present.
+ */
+
+#define pr_fmt(fmt) "thermal-testing: " fmt
+
+#include <linux/debugfs.h>
+#include <linux/module.h>
+
+#include "thermal_testing.h"
+
+struct dentry *d_testing;
+
+#define TT_COMMAND_SIZE		16
+
+enum tt_commands {
+	TT_CMD_ADDTZ,
+	TT_CMD_DELTZ,
+	TT_CMD_TZADDTRIP,
+	TT_CMD_TZREG,
+	TT_CMD_TZUNREG,
+};
+
+static const char *tt_command_strings[] = {
+	[TT_CMD_ADDTZ] = "addtz",
+	[TT_CMD_DELTZ] = "deltz",
+	[TT_CMD_TZADDTRIP] = "tzaddtrip",
+	[TT_CMD_TZREG] = "tzreg",
+	[TT_CMD_TZUNREG] = "tzunreg",
+};
+
+static int tt_command_exec(int index, const char *arg)
+{
+	int ret;
+
+	switch (index) {
+	case TT_CMD_ADDTZ:
+		ret = tt_add_tz();
+		break;
+
+	case TT_CMD_DELTZ:
+		ret = tt_del_tz(arg);
+		break;
+
+	case TT_CMD_TZADDTRIP:
+		ret = tt_zone_add_trip(arg);
+		break;
+
+	case TT_CMD_TZREG:
+		ret = tt_zone_reg(arg);
+		break;
+
+	case TT_CMD_TZUNREG:
+		ret = tt_zone_unreg(arg);
+		break;
+
+	default:
+		ret = -EINVAL;
+		break;
+	}
+
+	return ret;
+}
+
+static ssize_t tt_command_process(struct dentry *dentry, const char __user *user_buf,
+				  size_t count)
+{
+	char *buf __free(kfree);
+	char *arg;
+	int i;
+
+	buf = kmalloc(count + 1, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	if (copy_from_user(buf, user_buf, count))
+		return -EFAULT;
+
+	buf[count] = '\0';
+	strim(buf);
+
+	arg = strstr(buf, ":");
+	if (arg) {
+		*arg = '\0';
+		arg++;
+	}
+
+	for (i = 0; i < ARRAY_SIZE(tt_command_strings); i++) {
+		if (!strcmp(buf, tt_command_strings[i]))
+			return tt_command_exec(i, arg);
+	}
+
+	return -EINVAL;
+}
+
+static ssize_t tt_command_write(struct file *file, const char __user *user_buf,
+				size_t count, loff_t *ppos)
+{
+	struct dentry *dentry = file->f_path.dentry;
+	ssize_t ret;
+
+	if (*ppos)
+		return -EINVAL;
+
+	if (count + 1 > TT_COMMAND_SIZE)
+		return -E2BIG;
+
+	ret = debugfs_file_get(dentry);
+	if (unlikely(ret))
+		return ret;
+
+	ret = tt_command_process(dentry, user_buf, count);
+	if (ret)
+		return ret;
+
+	return count;
+}
+
+static const struct file_operations tt_command_fops = {
+	.write = tt_command_write,
+	.open =	 simple_open,
+	.llseek = default_llseek,
+};
+
+static int __init thermal_testing_init(void)
+{
+	d_testing = debugfs_create_dir("thermal-testing", NULL);
+	if (!IS_ERR(d_testing))
+		debugfs_create_file("command", 0200, d_testing, NULL,
+				    &tt_command_fops);
+
+	return 0;
+}
+module_init(thermal_testing_init);
+
+static void __exit thermal_testing_exit(void)
+{
+	debugfs_remove(d_testing);
+	tt_zone_cleanup();
+}
+module_exit(thermal_testing_exit);
+
+MODULE_DESCRIPTION("Thermal core testing facility");
+MODULE_LICENSE("GPL v2");
diff --git a/drivers/thermal/testing/thermal_testing.h b/drivers/thermal/testing/thermal_testing.h
new file mode 100644
index 000000000000..c790a32aae4e
--- /dev/null
+++ b/drivers/thermal/testing/thermal_testing.h
@@ -0,0 +1,11 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+extern struct dentry *d_testing;
+
+int tt_add_tz(void);
+int tt_del_tz(const char *arg);
+int tt_zone_add_trip(const char *arg);
+int tt_zone_reg(const char *arg);
+int tt_zone_unreg(const char *arg);
+
+void tt_zone_cleanup(void);
diff --git a/drivers/thermal/testing/zone.c b/drivers/thermal/testing/zone.c
new file mode 100644
index 000000000000..c6d8c66f40f9
--- /dev/null
+++ b/drivers/thermal/testing/zone.c
@@ -0,0 +1,468 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright 2024, Intel Corporation
+ *
+ * Author: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
+ *
+ * Thermal zone tempalates handling for thermal core testing.
+ */
+
+#define pr_fmt(fmt) "thermal-testing: " fmt
+
+#include <linux/debugfs.h>
+#include <linux/idr.h>
+#include <linux/list.h>
+#include <linux/thermal.h>
+#include <linux/workqueue.h>
+
+#include "thermal_testing.h"
+
+#define TT_MAX_FILE_NAME_LENGTH		16
+
+/**
+ * struct tt_thermal_zone - Testing thermal zone template
+ *
+ * Represents a template of a thermal zone that can be used for registering
+ * a test thermal zone with the thermal core.
+ *
+ * @list_node: Node in the list of all testing thermal zone templates.
+ * @trips: List of trip point templates for this thermal zone template.
+ * @d_tt_zone: Directory in debugfs representing this template.
+ * @tz: Test thermal zone based on this template, if present.
+ * @lock: Mutex for synchronizing changes of this template.
+ * @ida: IDA for trip point IDs.
+ * @id: The ID of this template for the debugfs interface.
+ * @temp: Temperature value.
+ * @tz_temp: Current thermal zone temperature (after registration).
+ * @num_trips: Number of trip points in the @trips list.
+ * @refcount: Reference counter for usage and removal synchronization.
+ */
+struct tt_thermal_zone {
+	struct list_head list_node;
+	struct list_head trips;
+	struct dentry *d_tt_zone;
+	struct thermal_zone_device *tz;
+	struct mutex lock;
+	struct ida ida;
+	int id;
+	int temp;
+	int tz_temp;
+	unsigned int num_trips;
+	unsigned int refcount;
+};
+
+DEFINE_GUARD(tt_zone, struct tt_thermal_zone *, mutex_lock(&_T->lock), mutex_unlock(&_T->lock))
+
+/**
+ * struct tt_trip - Testing trip point template
+ *
+ * Represents a template of a trip point to be used for populating a trip point
+ * during the registration of a thermal zone based on a given zone template.
+ *
+ * @list_node: Node in the list of all trip templates in the zone template.
+ * @trip: Trip point data to use for thernal zone registration.
+ * @id: The ID of this trip template for the debugfs interface.
+ */
+struct tt_trip {
+	struct list_head list_node;
+	struct thermal_trip trip;
+	int id;
+};
+
+/*
+ * It is both questionable and potentially problematic from the sychnronization
+ * perspective to attempt to manipulate debugfs from within a debugfs file
+ * "write" operation, so auxiliary work items are used for that.  The majority
+ * of zone-related command functions have a part that runs from a workqueue and
+ * make changes in debugs, among other things.
+ */
+struct tt_work {
+	struct work_struct work;
+	struct tt_thermal_zone *tt_zone;
+	struct tt_trip *tt_trip;
+};
+
+static inline struct tt_work *tt_work_of_work(struct work_struct *work)
+{
+	return container_of(work, struct tt_work, work);
+}
+
+static LIST_HEAD(tt_thermal_zones);
+static DEFINE_IDA(tt_thermal_zones_ida);
+static DEFINE_MUTEX(tt_thermal_zones_lock);
+
+static int tt_int_get(void *data, u64 *val)
+{
+	*val = *(int *)data;
+	return 0;
+}
+static int tt_int_set(void *data, u64 val)
+{
+	if ((int)val < THERMAL_TEMP_INVALID)
+		return -EINVAL;
+
+	*(int *)data = val;
+	return 0;
+}
+DEFINE_DEBUGFS_ATTRIBUTE_SIGNED(tt_int_attr, tt_int_get, tt_int_set, "%lld\n");
+DEFINE_DEBUGFS_ATTRIBUTE(tt_unsigned_int_attr, tt_int_get, tt_int_set, "%llu\n");
+
+static int tt_zone_tz_temp_get(void *data, u64 *val)
+{
+	struct tt_thermal_zone *tt_zone = data;
+
+	guard(tt_zone)(tt_zone);
+
+	if (!tt_zone->tz)
+		return -EBUSY;
+
+	*val = tt_zone->tz_temp;
+
+	return 0;
+}
+static int tt_zone_tz_temp_set(void *data, u64 val)
+{
+	struct tt_thermal_zone *tt_zone = data;
+
+	guard(tt_zone)(tt_zone);
+
+	if (!tt_zone->tz)
+		return -EBUSY;
+
+	WRITE_ONCE(tt_zone->tz_temp, val);
+	thermal_zone_device_update(tt_zone->tz, THERMAL_EVENT_TEMP_SAMPLE);
+
+	return 0;
+}
+DEFINE_DEBUGFS_ATTRIBUTE_SIGNED(tt_zone_tz_temp_attr, tt_zone_tz_temp_get,
+				tt_zone_tz_temp_set, "%lld\n");
+
+static void tt_zone_free_trips(struct tt_thermal_zone *tt_zone)
+{
+	struct tt_trip *tt_trip, *aux;
+
+	list_for_each_entry_safe(tt_trip, aux, &tt_zone->trips, list_node) {
+		list_del(&tt_trip->list_node);
+		ida_free(&tt_zone->ida, tt_trip->id);
+		kfree(tt_trip);
+	}
+}
+
+static void tt_zone_free(struct tt_thermal_zone *tt_zone)
+{
+	tt_zone_free_trips(tt_zone);
+	ida_free(&tt_thermal_zones_ida, tt_zone->id);
+	ida_destroy(&tt_zone->ida);
+	kfree(tt_zone);
+}
+
+static void tt_add_tz_work_fn(struct work_struct *work)
+{
+	struct tt_work *tt_work = tt_work_of_work(work);
+	struct tt_thermal_zone *tt_zone = tt_work->tt_zone;
+	char f_name[TT_MAX_FILE_NAME_LENGTH];
+
+	kfree(tt_work);
+
+	snprintf(f_name, TT_MAX_FILE_NAME_LENGTH, "tz%d", tt_zone->id);
+	tt_zone->d_tt_zone = debugfs_create_dir(f_name, d_testing);
+	if (IS_ERR(tt_zone->d_tt_zone)) {
+		tt_zone_free(tt_zone);
+		return;
+	}
+
+	debugfs_create_file_unsafe("temp", 0600, tt_zone->d_tt_zone, tt_zone,
+				   &tt_zone_tz_temp_attr);
+
+	debugfs_create_file_unsafe("init_temp", 0600, tt_zone->d_tt_zone,
+				   &tt_zone->temp, &tt_int_attr);
+
+	guard(mutex)(&tt_thermal_zones_lock);
+
+	list_add_tail(&tt_zone->list_node, &tt_thermal_zones);
+}
+
+int tt_add_tz(void)
+{
+	struct tt_thermal_zone *tt_zone __free(kfree);
+	struct tt_work *tt_work __free(kfree);
+	int ret;
+
+	tt_zone = kzalloc(sizeof(*tt_zone), GFP_KERNEL);
+	if (!tt_zone)
+		return -ENOMEM;
+
+	tt_work = kzalloc(sizeof(*tt_work), GFP_KERNEL);
+	if (!tt_work)
+		return -ENOMEM;
+
+	INIT_LIST_HEAD(&tt_zone->trips);
+	mutex_init(&tt_zone->lock);
+	ida_init(&tt_zone->ida);
+	tt_zone->temp = THERMAL_TEMP_INVALID;
+
+	ret = ida_alloc(&tt_thermal_zones_ida, GFP_KERNEL);
+	if (ret < 0)
+		return ret;
+
+	tt_zone->id = ret;
+
+	INIT_WORK(&tt_work->work, tt_add_tz_work_fn);
+	tt_work->tt_zone = no_free_ptr(tt_zone);
+	schedule_work(&(no_free_ptr(tt_work)->work));
+
+	return 0;
+}
+
+static void tt_del_tz_work_fn(struct work_struct *work)
+{
+	struct tt_work *tt_work = tt_work_of_work(work);
+	struct tt_thermal_zone *tt_zone = tt_work->tt_zone;
+
+	kfree(tt_work);
+
+	debugfs_remove(tt_zone->d_tt_zone);
+	tt_zone_free(tt_zone);
+}
+
+static void tt_zone_unregister_tz(struct tt_thermal_zone *tt_zone)
+{
+	guard(tt_zone)(tt_zone);
+
+	if (tt_zone->tz) {
+		thermal_zone_device_unregister(tt_zone->tz);
+		tt_zone->tz = NULL;
+	}
+}
+
+int tt_del_tz(const char *arg)
+{
+	struct tt_work *tt_work __free(kfree);
+	struct tt_thermal_zone *tt_zone, *aux;
+	int ret;
+	int id;
+
+	ret = sscanf(arg, "%d", &id);
+	if (ret != 1)
+		return -EINVAL;
+
+	tt_work = kzalloc(sizeof(*tt_work), GFP_KERNEL);
+	if (!tt_work)
+		return -ENOMEM;
+
+	guard(mutex)(&tt_thermal_zones_lock);
+
+	ret = -EINVAL;
+	list_for_each_entry_safe(tt_zone, aux, &tt_thermal_zones, list_node) {
+		if (tt_zone->id == id) {
+			if (tt_zone->refcount) {
+				ret = -EBUSY;
+			} else {
+				list_del(&tt_zone->list_node);
+				ret = 0;
+			}
+			break;
+		}
+	}
+
+	if (ret)
+		return ret;
+
+	tt_zone_unregister_tz(tt_zone);
+
+	INIT_WORK(&tt_work->work, tt_del_tz_work_fn);
+	tt_work->tt_zone = tt_zone;
+	schedule_work(&(no_free_ptr(tt_work)->work));
+
+	return 0;
+}
+
+static struct tt_thermal_zone *tt_get_tt_zone(const char *arg)
+{
+	struct tt_thermal_zone *tt_zone;
+	int ret, id;
+
+	ret = sscanf(arg, "%d", &id);
+	if (ret != 1)
+		return ERR_PTR(-EINVAL);
+
+	guard(mutex)(&tt_thermal_zones_lock);
+
+	ret = -EINVAL;
+	list_for_each_entry(tt_zone, &tt_thermal_zones, list_node) {
+		if (tt_zone->id == id) {
+			tt_zone->refcount++;
+			ret = 0;
+			break;
+		}
+	}
+
+	if (ret)
+		return ERR_PTR(ret);
+
+	return tt_zone;
+}
+
+static void tt_put_tt_zone(struct tt_thermal_zone *tt_zone)
+{
+	guard(mutex)(&tt_thermal_zones_lock);
+
+	tt_zone->refcount--;
+}
+
+static void tt_zone_add_trip_work_fn(struct work_struct *work)
+{
+	struct tt_work *tt_work = tt_work_of_work(work);
+	struct tt_thermal_zone *tt_zone = tt_work->tt_zone;
+	struct tt_trip *tt_trip = tt_work->tt_trip;
+	char d_name[TT_MAX_FILE_NAME_LENGTH];
+
+	kfree(tt_work);
+
+	snprintf(d_name, TT_MAX_FILE_NAME_LENGTH, "trip_%d_temp", tt_trip->id);
+	debugfs_create_file_unsafe(d_name, 0600, tt_zone->d_tt_zone,
+				   &tt_trip->trip.temperature, &tt_int_attr);
+
+	snprintf(d_name, TT_MAX_FILE_NAME_LENGTH, "trip_%d_hyst", tt_trip->id);
+	debugfs_create_file_unsafe(d_name, 0600, tt_zone->d_tt_zone,
+				   &tt_trip->trip.hysteresis, &tt_unsigned_int_attr);
+
+	tt_put_tt_zone(tt_zone);
+}
+
+int tt_zone_add_trip(const char *arg)
+{
+	struct tt_work *tt_work __free(kfree);
+	struct tt_trip *tt_trip __free(kfree);
+	struct tt_thermal_zone *tt_zone;
+	int id;
+
+	tt_work = kzalloc(sizeof(*tt_work), GFP_KERNEL);
+	if (!tt_work)
+		return -ENOMEM;
+
+	tt_trip = kzalloc(sizeof(*tt_trip), GFP_KERNEL);
+	if (!tt_trip)
+		return -ENOMEM;
+
+	tt_zone = tt_get_tt_zone(arg);
+	if (IS_ERR(tt_zone))
+		return PTR_ERR(tt_zone);
+
+	id = ida_alloc(&tt_zone->ida, GFP_KERNEL);
+	if (id < 0) {
+		tt_put_tt_zone(tt_zone);
+		return id;
+	}
+
+	tt_trip->trip.type = THERMAL_TRIP_ACTIVE;
+	tt_trip->trip.temperature = THERMAL_TEMP_INVALID;
+	tt_trip->trip.flags = THERMAL_TRIP_FLAG_RW;
+	tt_trip->id = id;
+
+	guard(tt_zone)(tt_zone);
+
+	list_add_tail(&tt_trip->list_node, &tt_zone->trips);
+	tt_zone->num_trips++;
+
+	INIT_WORK(&tt_work->work, tt_zone_add_trip_work_fn);
+	tt_work->tt_zone = tt_zone;
+	tt_work->tt_trip = no_free_ptr(tt_trip);
+	schedule_work(&(no_free_ptr(tt_work)->work));
+
+	return 0;
+}
+
+static int tt_zone_get_temp(struct thermal_zone_device *tz, int *temp)
+{
+	struct tt_thermal_zone *tt_zone = thermal_zone_device_priv(tz);
+
+	*temp = READ_ONCE(tt_zone->tz_temp);
+
+	if (*temp < THERMAL_TEMP_INVALID)
+		return -ENODATA;
+
+	return 0;
+}
+
+static struct thermal_zone_device_ops tt_zone_ops = {
+	.get_temp = tt_zone_get_temp,
+};
+
+static int tt_zone_register_tz(struct tt_thermal_zone *tt_zone)
+{
+	struct thermal_trip *trips __free(kfree);
+	struct thermal_zone_device *tz;
+	struct tt_trip *tt_trip;
+	int i;
+
+	guard(tt_zone)(tt_zone);
+
+	if (tt_zone->tz)
+		return -EINVAL;
+
+	trips = kcalloc(tt_zone->num_trips, sizeof(*trips), GFP_KERNEL);
+	if (!trips)
+		return -ENOMEM;
+
+	i = 0;
+	list_for_each_entry(tt_trip, &tt_zone->trips, list_node)
+		trips[i++] = tt_trip->trip;
+
+	tt_zone->tz_temp = tt_zone->temp;
+
+	tz = thermal_zone_device_register_with_trips("test_tz", trips, i, tt_zone,
+						     &tt_zone_ops, NULL, 0, 0);
+	if (IS_ERR(tz))
+		return PTR_ERR(tz);
+
+	tt_zone->tz = tz;
+
+	thermal_zone_device_enable(tz);
+
+	return 0;
+}
+
+int tt_zone_reg(const char *arg)
+{
+	struct tt_thermal_zone *tt_zone;
+	int ret;
+
+	tt_zone = tt_get_tt_zone(arg);
+	if (IS_ERR(tt_zone))
+		return PTR_ERR(tt_zone);
+
+	ret = tt_zone_register_tz(tt_zone);
+
+	tt_put_tt_zone(tt_zone);
+
+	return ret;
+}
+
+int tt_zone_unreg(const char *arg)
+{
+	struct tt_thermal_zone *tt_zone;
+
+	tt_zone = tt_get_tt_zone(arg);
+	if (IS_ERR(tt_zone))
+		return PTR_ERR(tt_zone);
+
+	tt_zone_unregister_tz(tt_zone);
+
+	tt_put_tt_zone(tt_zone);
+
+	return 0;
+}
+
+void tt_zone_cleanup(void)
+{
+	struct tt_thermal_zone *tt_zone, *aux;
+
+	list_for_each_entry_safe(tt_zone, aux, &tt_thermal_zones, list_node) {
+		tt_zone_unregister_tz(tt_zone);
+
+		list_del(&tt_zone->list_node);
+
+		tt_zone_free(tt_zone);
+	}
+}