path: root/drivers/thermal/thermal_core.c

// SPDX-License-Identifier: GPL-2.0
/*
 *  thermal.c - Generic Thermal Management Sysfs support.
 *
 *  Copyright (C) 2008 Intel Corp
 *  Copyright (C) 2008 Zhang Rui <rui.zhang@intel.com>
 *  Copyright (C) 2008 Sujith Thomas <sujith.thomas@intel.com>
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/module.h>
#include <linux/device.h>
#include <linux/err.h>
#include <linux/slab.h>
#include <linux/kdev_t.h>
#include <linux/idr.h>
#include <linux/thermal.h>
#include <linux/reboot.h>
#include <linux/string.h>
#include <linux/of.h>
#include <linux/suspend.h>

#define CREATE_TRACE_POINTS
#include <trace/events/thermal.h>

#include "thermal_core.h"
#include "thermal_hwmon.h"

MODULE_AUTHOR("Zhang Rui");
MODULE_DESCRIPTION("Generic thermal management sysfs support");
MODULE_LICENSE("GPL v2");

static DEFINE_IDA(thermal_tz_ida);
static DEFINE_IDA(thermal_cdev_ida);

static LIST_HEAD(thermal_tz_list);
static LIST_HEAD(thermal_cdev_list);
static LIST_HEAD(thermal_governor_list);

static DEFINE_MUTEX(thermal_list_lock);
static DEFINE_MUTEX(thermal_governor_lock);
static DEFINE_MUTEX(poweroff_lock);

static atomic_t in_suspend;
static bool power_off_triggered;

static struct thermal_governor *def_governor;

/*
 * Governor section: set of functions to handle thermal governors
 *
 * Functions to help in the life cycle of thermal governors within
 * the thermal core and by the thermal governor code.
 */

static struct thermal_governor *__find_governor(const char *name)
{
	struct thermal_governor *pos;

	if (!name || !name[0])
		return def_governor;

	list_for_each_entry(pos, &thermal_governor_list, governor_list)
		if (!strncasecmp(name, pos->name, THERMAL_NAME_LENGTH))
			return pos;

	return NULL;
}

/**
 * bind_previous_governor() - bind the previous governor of the thermal zone
 * @tz:		a valid pointer to a struct thermal_zone_device
 * @failed_gov_name:	the name of the governor that failed to register
 *
 * Register the previous governor of the thermal zone after a new
 * governor has failed to be bound.
 */
static void bind_previous_governor(struct thermal_zone_device *tz,
				   const char *failed_gov_name)
{
	if (tz->governor && tz->governor->bind_to_tz) {
		if (tz->governor->bind_to_tz(tz)) {
			dev_err(&tz->device,
				"governor %s failed to bind and the previous one (%s) failed to bind again, thermal zone %s has no governor\n",
				failed_gov_name, tz->governor->name, tz->type);
			tz->governor = NULL;
		}
	}
}

/**
 * thermal_set_governor() - Switch to another governor
 * @tz:		a valid pointer to a struct thermal_zone_device
 * @new_gov:	pointer to the new governor
 *
 * Change the governor of thermal zone @tz.
 *
 * Return: 0 on success, an error if the new governor's bind_to_tz() failed.
 */
static int thermal_set_governor(struct thermal_zone_device *tz,
				struct thermal_governor *new_gov)
{
	int ret = 0;

	if (tz->governor && tz->governor->unbind_from_tz)
		tz->governor->unbind_from_tz(tz);

	if (new_gov && new_gov->bind_to_tz) {
		ret = new_gov->bind_to_tz(tz);
		if (ret) {
			bind_previous_governor(tz, new_gov->name);

			return ret;
		}
	}

	tz->governor = new_gov;

	return ret;
}

int thermal_register_governor(struct thermal_governor *governor)
{
	int err;
	const char *name;
	struct thermal_zone_device *pos;

	if (!governor)
		return -EINVAL;

	mutex_lock(&thermal_governor_lock);

	err = -EBUSY;
	if (!__find_governor(governor->name)) {
		bool match_default;

		err = 0;
		list_add(&governor->governor_list, &thermal_governor_list);
		match_default = !strncmp(governor->name,
					 DEFAULT_THERMAL_GOVERNOR,
					 THERMAL_NAME_LENGTH);

		if (!def_governor && match_default)
			def_governor = governor;
	}

	mutex_lock(&thermal_list_lock);

	list_for_each_entry(pos, &thermal_tz_list, node) {
		/*
		 * only thermal zones with specified tz->tzp->governor_name
		 * may run with tz->govenor unset
		 */
		if (pos->governor)
			continue;

		name = pos->tzp->governor_name;

		if (!strncasecmp(name, governor->name, THERMAL_NAME_LENGTH)) {
			int ret;

			ret = thermal_set_governor(pos, governor);
			if (ret)
				dev_err(&pos->device,
					"Failed to set governor %s for thermal zone %s: %d\n",
					governor->name, pos->type, ret);
		}
	}

	mutex_unlock(&thermal_list_lock);
	mutex_unlock(&thermal_governor_lock);

	return err;
}

void thermal_unregister_governor(struct thermal_governor *governor)
{
	struct thermal_zone_device *pos;

	if (!governor)
		return;

	mutex_lock(&thermal_governor_lock);

	if (!__find_governor(governor->name))
		goto exit;

	mutex_lock(&thermal_list_lock);

	list_for_each_entry(pos, &thermal_tz_list, node) {
		if (!strncasecmp(pos->governor->name, governor->name,
				 THERMAL_NAME_LENGTH))
			thermal_set_governor(pos, NULL);
	}

	mutex_unlock(&thermal_list_lock);
	list_del(&governor->governor_list);
exit:
	mutex_unlock(&thermal_governor_lock);
}

int thermal_zone_device_set_policy(struct thermal_zone_device *tz,
				   char *policy)
{
	struct thermal_governor *gov;
	int ret = -EINVAL;

	mutex_lock(&thermal_governor_lock);
	mutex_lock(&tz->lock);

	gov = __find_governor(strim(policy));
	if (!gov)
		goto exit;

	ret = thermal_set_governor(tz, gov);

exit:
	mutex_unlock(&tz->lock);
	mutex_unlock(&thermal_governor_lock);

	return ret;
}

int thermal_build_list_of_policies(char *buf)
{
	struct thermal_governor *pos;
	ssize_t count = 0;
	ssize_t size = PAGE_SIZE;

	mutex_lock(&thermal_governor_lock);

	list_for_each_entry(pos, &thermal_governor_list, governor_list) {
		size = PAGE_SIZE - count;
		count += scnprintf(buf + count, size, "%s ", pos->name);
	}
	count += scnprintf(buf + count, size, "\n");

	mutex_unlock(&thermal_governor_lock);

	return count;
}

static void __init thermal_unregister_governors(void)
{
	struct thermal_governor **governor;

	for_each_governor_table(governor)
		thermal_unregister_governor(*governor);
}

static int __init thermal_register_governors(void)
{
	int ret = 0;
	struct thermal_governor **governor;

	for_each_governor_table(governor) {
		ret = thermal_register_governor(*governor);
		if (ret) {
			pr_err("Failed to register governor: '%s'",
			       (*governor)->name);
			break;
		}

		pr_info("Registered thermal governor '%s'",
			(*governor)->name);
	}

	if (ret) {
		struct thermal_governor **gov;

		for_each_governor_table(gov) {
			if (gov == governor)
				break;
			thermal_unregister_governor(*gov);
		}
	}

	return ret;
}

/*
 * Zone update section: main control loop applied to each zone while monitoring
 *
 * in polling mode. The monitoring is done using a workqueue.
 * Same update may be done on a zone by calling thermal_zone_device_update().
 *
 * An update means:
 * - Non-critical trips will invoke the governor responsible for that zone;
 * - Hot trips will produce a notification to userspace;
 * - Critical trip point will cause a system shutdown