drivers/leds/trigger/ledtrig-activity.c - linux/kernel/git/gregkh/driver-core - Git at Google

 // SPDX-License-Identifier: GPL-2.0-only
 /*
  * Activity LED trigger
  *
  * Copyright (C) 2017 Willy Tarreau <w@1wt.eu>
  * Partially based on Atsushi Nemoto's ledtrig-heartbeat.c.
  */

 #include <linux/init.h>
 #include <linux/kernel.h>
 #include <linux/kernel_stat.h>
 #include <linux/leds.h>
 #include <linux/module.h>
 #include <linux/reboot.h>
 #include <linux/sched.h>
 #include <linux/slab.h>
 #include <linux/timer.h>
 #include "../leds.h"

 static int panic_detected;

 struct activity_data {
 	struct timer_list timer;
 	struct led_classdev *led_cdev;
 	u64 last_used;
 	u64 last_boot;
 	int time_left;
 	int state;
 	int invert;
 };

 static void led_activity_function(struct timer_list *t)
 {
 	struct activity_data *activity_data = from_timer(activity_data, t,
 							 timer);
 	struct led_classdev *led_cdev = activity_data->led_cdev;
 	unsigned int target;
 	unsigned int usage;
 	int delay;
 	u64 curr_used;
 	u64 curr_boot;
 	s32 diff_used;
 	s32 diff_boot;
 	int cpus;
 	int i;

 	if (test_and_clear_bit(LED_BLINK_BRIGHTNESS_CHANGE, &led_cdev->work_flags))
 		led_cdev->blink_brightness = led_cdev->new_blink_brightness;

 	if (unlikely(panic_detected)) {
 		/* full brightness in case of panic */
 		led_set_brightness_nosleep(led_cdev, led_cdev->blink_brightness);
 		return;
 	}

 	cpus = 0;
 	curr_used = 0;

 	for_each_possible_cpu(i) {
 		struct kernel_cpustat kcpustat;

 		kcpustat_cpu_fetch(&kcpustat, i);

 		curr_used += kcpustat.cpustat[CPUTIME_USER]
 			  +  kcpustat.cpustat[CPUTIME_NICE]
 			  +  kcpustat.cpustat[CPUTIME_SYSTEM]
 			  +  kcpustat.cpustat[CPUTIME_SOFTIRQ]
 			  +  kcpustat.cpustat[CPUTIME_IRQ];
 		cpus++;
 	}

 	/* We come here every 100ms in the worst case, so that's 100M ns of
 	 * cumulated time. By dividing by 2^16, we get the time resolution
 	 * down to 16us, ensuring we won't overflow 32-bit computations below
 	 * even up to 3k CPUs, while keeping divides cheap on smaller systems.
 	 */
 	curr_boot = ktime_get_boottime_ns() * cpus;
 	diff_boot = (curr_boot - activity_data->last_boot) >> 16;
 	diff_used = (curr_used - activity_data->last_used) >> 16;
 	activity_data->last_boot = curr_boot;
 	activity_data->last_used = curr_used;

 	if (diff_boot <= 0 || diff_used < 0)
 		usage = 0;
 	else if (diff_used >= diff_boot)
 		usage = 100;
 	else
 		usage = 100 * diff_used / diff_boot;

 	/*
 	 * Now we know the total boot_time multiplied by the number of CPUs, and
 	 * the total idle+wait time for all CPUs. We'll compare how they evolved
 	 * since last call. The % of overall CPU usage is :
 	 *
 	 *      1 - delta_idle / delta_boot
 	 *
 	 * What we want is that when the CPU usage is zero, the LED must blink
 	 * slowly with very faint flashes that are detectable but not disturbing
 	 * (typically 10ms every second, or 10ms ON, 990ms OFF). Then we want
 	 * blinking frequency to increase up to the point where the load is
 	 * enough to saturate one core in multi-core systems or 50% in single
 	 * core systems. At this point it should reach 10 Hz with a 10/90 duty
 	 * cycle (10ms ON, 90ms OFF). After this point, the blinking frequency
 	 * remains stable (10 Hz) and only the duty cycle increases to report
 	 * the activity, up to the point where we have 90ms ON, 10ms OFF when
 	 * all cores are saturated. It's important that the LED never stays in
 	 * a steady state so that it's easy to distinguish an idle or saturated
 	 * machine from a hung one.
 	 *
 	 * This gives us :
 	 *   - a target CPU usage of min(50%, 100%/#CPU) for a 10% duty cycle
 	 *     (10ms ON, 90ms OFF)
 	 *   - below target :
 	 *      ON_ms  = 10
 	 *      OFF_ms = 90 + (1 - usage/target) * 900
 	 *   - above target :
 	 *      ON_ms  = 10 + (usage-target)/(100%-target) * 80
 	 *      OFF_ms = 90 - (usage-target)/(100%-target) * 80
 	 *
 	 * In order to keep a good responsiveness, we cap the sleep time to
 	 * 100 ms and keep track of the sleep time left. This allows us to
 	 * quickly change it if needed.
 	 */

 	activity_data->time_left -= 100;
 	if (activity_data->time_left <= 0) {
 		activity_data->time_left = 0;
 		activity_data->state = !activity_data->state;
 		led_set_brightness_nosleep(led_cdev,
 			(activity_data->state ^ activity_data->invert) ?
 			led_cdev->blink_brightness : LED_OFF);
 	}

 	target = (cpus > 1) ? (100 / cpus) : 50;

 	if (usage < target)
 		delay = activity_data->state ?
 			10 :                        /* ON  */
 			990 - 900 * usage / target; /* OFF */
 	else
 		delay = activity_data->state ?
 			10 + 80 * (usage - target) / (100 - target) : /* ON  */
 			90 - 80 * (usage - target) / (100 - target);  /* OFF */


 	if (!activity_data->time_left || delay <= activity_data->time_left)
 		activity_data->time_left = delay;

 	delay = min_t(int, activity_data->time_left, 100);
 	mod_timer(&activity_data->timer, jiffies + msecs_to_jiffies(delay));
 }

 static ssize_t led_invert_show(struct device *dev,
                                struct device_attribute *attr, char *buf)
 {
 	struct activity_data *activity_data = led_trigger_get_drvdata(dev);

 	return sprintf(buf, "%u\n", activity_data->invert);
 }

 static ssize_t led_invert_store(struct device *dev,
                                 struct device_attribute *attr,
                                 const char *buf, size_t size)
 {
 	struct activity_data *activity_data = led_trigger_get_drvdata(dev);
 	unsigned long state;
 	int ret;

 	ret = kstrtoul(buf, 0, &state);
 	if (ret)
 		return ret;

 	activity_data->invert = !!state;

 	return size;
 }

 static DEVICE_ATTR(invert, 0644, led_invert_show, led_invert_store);

 static struct attribute *activity_led_attrs[] = {
 	&dev_attr_invert.attr,
 	NULL
 };
 ATTRIBUTE_GROUPS(activity_led);

 static int activity_activate(struct led_classdev *led_cdev)
 {
 	struct activity_data *activity_data;

 	activity_data = kzalloc(sizeof(*activity_data), GFP_KERNEL);
 	if (!activity_data)
 		return -ENOMEM;

 	led_set_trigger_data(led_cdev, activity_data);

 	activity_data->led_cdev = led_cdev;
 	timer_setup(&activity_data->timer, led_activity_function, 0);
 	if (!led_cdev->blink_brightness)
 		led_cdev->blink_brightness = led_cdev->max_brightness;
 	led_activity_function(&activity_data->timer);
 	set_bit(LED_BLINK_SW, &led_cdev->work_flags);

 	return 0;
 }

 static void activity_deactivate(struct led_classdev *led_cdev)
 {
 	struct activity_data *activity_data = led_get_trigger_data(led_cdev);

 	del_timer_sync(&activity_data->timer);
 	kfree(activity_data);
 	clear_bit(LED_BLINK_SW, &led_cdev->work_flags);
 }

 static struct led_trigger activity_led_trigger = {
 	.name       = "activity",
 	.activate   = activity_activate,
 	.deactivate = activity_deactivate,
 	.groups     = activity_led_groups,
 };

 static int activity_reboot_notifier(struct notifier_block *nb,
                                     unsigned long code, void *unused)
 {
 	led_trigger_unregister(&activity_led_trigger);
 	return NOTIFY_DONE;
 }

 static int activity_panic_notifier(struct notifier_block *nb,
                                    unsigned long code, void *unused)
 {
 	panic_detected = 1;
 	return NOTIFY_DONE;
 }

 static struct notifier_block activity_reboot_nb = {
 	.notifier_call = activity_reboot_notifier,
 };

 static struct notifier_block activity_panic_nb = {
 	.notifier_call = activity_panic_notifier,
 };

 static int __init activity_init(void)
 {
 	int rc = led_trigger_register(&activity_led_trigger);

 	if (!rc) {
 		atomic_notifier_chain_register(&panic_notifier_list,
 					       &activity_panic_nb);
 		register_reboot_notifier(&activity_reboot_nb);
 	}
 	return rc;
 }

 static void __exit activity_exit(void)
 {
 	unregister_reboot_notifier(&activity_reboot_nb);
 	atomic_notifier_chain_unregister(&panic_notifier_list,
 					 &activity_panic_nb);
 	led_trigger_unregister(&activity_led_trigger);
 }

 module_init(activity_init);
 module_exit(activity_exit);

 MODULE_AUTHOR("Willy Tarreau <w@1wt.eu>");
 MODULE_DESCRIPTION("Activity LED trigger");
 MODULE_LICENSE("GPL v2");
	// SPDX-License-Identifier: GPL-2.0-only
	/*
	* Activity LED trigger
	*
	* Copyright (C) 2017 Willy Tarreau <w@1wt.eu>
	* Partially based on Atsushi Nemoto's ledtrig-heartbeat.c.
	*/

	#include <linux/init.h>
	#include <linux/kernel.h>
	#include <linux/kernel_stat.h>
	#include <linux/leds.h>
	#include <linux/module.h>
	#include <linux/reboot.h>
	#include <linux/sched.h>
	#include <linux/slab.h>
	#include <linux/timer.h>
	#include "../leds.h"

	static int panic_detected;

	struct activity_data {
	struct timer_list timer;
	struct led_classdev *led_cdev;
	u64 last_used;
	u64 last_boot;
	int time_left;
	int state;
	int invert;
	};

	static void led_activity_function(struct timer_list *t)
	{
	struct activity_data *activity_data = from_timer(activity_data, t,
	timer);
	struct led_classdev *led_cdev = activity_data->led_cdev;
	unsigned int target;
	unsigned int usage;
	int delay;
	u64 curr_used;
	u64 curr_boot;
	s32 diff_used;
	s32 diff_boot;
	int cpus;
	int i;

	if (test_and_clear_bit(LED_BLINK_BRIGHTNESS_CHANGE, &led_cdev->work_flags))
	led_cdev->blink_brightness = led_cdev->new_blink_brightness;

	if (unlikely(panic_detected)) {
	/* full brightness in case of panic */
	led_set_brightness_nosleep(led_cdev, led_cdev->blink_brightness);
	return;
	}

	cpus = 0;
	curr_used = 0;

	for_each_possible_cpu(i) {
	struct kernel_cpustat kcpustat;

	kcpustat_cpu_fetch(&kcpustat, i);

	curr_used += kcpustat.cpustat[CPUTIME_USER]
	+ kcpustat.cpustat[CPUTIME_NICE]
	+ kcpustat.cpustat[CPUTIME_SYSTEM]
	+ kcpustat.cpustat[CPUTIME_SOFTIRQ]
	+ kcpustat.cpustat[CPUTIME_IRQ];
	cpus++;
	}

	/* We come here every 100ms in the worst case, so that's 100M ns of
	* cumulated time. By dividing by 2^16, we get the time resolution
	* down to 16us, ensuring we won't overflow 32-bit computations below
	* even up to 3k CPUs, while keeping divides cheap on smaller systems.
	*/
	curr_boot = ktime_get_boottime_ns() * cpus;
	diff_boot = (curr_boot - activity_data->last_boot) >> 16;
	diff_used = (curr_used - activity_data->last_used) >> 16;
	activity_data->last_boot = curr_boot;
	activity_data->last_used = curr_used;

	if (diff_boot <= 0 \|\| diff_used < 0)
	usage = 0;
	else if (diff_used >= diff_boot)
	usage = 100;
	else
	usage = 100 * diff_used / diff_boot;

	/*
	* Now we know the total boot_time multiplied by the number of CPUs, and
	* the total idle+wait time for all CPUs. We'll compare how they evolved
	* since last call. The % of overall CPU usage is :
	*
	* 1 - delta_idle / delta_boot
	*
	* What we want is that when the CPU usage is zero, the LED must blink
	* slowly with very faint flashes that are detectable but not disturbing
	* (typically 10ms every second, or 10ms ON, 990ms OFF). Then we want
	* blinking frequency to increase up to the point where the load is
	* enough to saturate one core in multi-core systems or 50% in single
	* core systems. At this point it should reach 10 Hz with a 10/90 duty
	* cycle (10ms ON, 90ms OFF). After this point, the blinking frequency
	* remains stable (10 Hz) and only the duty cycle increases to report
	* the activity, up to the point where we have 90ms ON, 10ms OFF when
	* all cores are saturated. It's important that the LED never stays in
	* a steady state so that it's easy to distinguish an idle or saturated
	* machine from a hung one.
	*
	* This gives us :
	* - a target CPU usage of min(50%, 100%/#CPU) for a 10% duty cycle
	* (10ms ON, 90ms OFF)
	* - below target :
	* ON_ms = 10
	* OFF_ms = 90 + (1 - usage/target) * 900
	* - above target :
	* ON_ms = 10 + (usage-target)/(100%-target) * 80
	* OFF_ms = 90 - (usage-target)/(100%-target) * 80
	*
	* In order to keep a good responsiveness, we cap the sleep time to
	* 100 ms and keep track of the sleep time left. This allows us to
	* quickly change it if needed.
	*/

	activity_data->time_left -= 100;
	if (activity_data->time_left <= 0) {
	activity_data->time_left = 0;
	activity_data->state = !activity_data->state;
	led_set_brightness_nosleep(led_cdev,
	(activity_data->state ^ activity_data->invert) ?
	led_cdev->blink_brightness : LED_OFF);
	}

	target = (cpus > 1) ? (100 / cpus) : 50;

	if (usage < target)
	delay = activity_data->state ?
	10 : /* ON */
	990 - 900 * usage / target; /* OFF */
	else
	delay = activity_data->state ?
	10 + 80 * (usage - target) / (100 - target) : /* ON */
	90 - 80 * (usage - target) / (100 - target); /* OFF */


	if (!activity_data->time_left \|\| delay <= activity_data->time_left)
	activity_data->time_left = delay;

	delay = min_t(int, activity_data->time_left, 100);
	mod_timer(&activity_data->timer, jiffies + msecs_to_jiffies(delay));
	}

	static ssize_t led_invert_show(struct device *dev,
	struct device_attribute attr, char buf)
	{
	struct activity_data *activity_data = led_trigger_get_drvdata(dev);

	return sprintf(buf, "%u\n", activity_data->invert);
	}

	static ssize_t led_invert_store(struct device *dev,
	struct device_attribute *attr,
	const char *buf, size_t size)
	{
	struct activity_data *activity_data = led_trigger_get_drvdata(dev);
	unsigned long state;
	int ret;

	ret = kstrtoul(buf, 0, &state);
	if (ret)
	return ret;

	activity_data->invert = !!state;

	return size;
	}

	static DEVICE_ATTR(invert, 0644, led_invert_show, led_invert_store);

	static struct attribute *activity_led_attrs[] = {
	&dev_attr_invert.attr,
	NULL
	};
	ATTRIBUTE_GROUPS(activity_led);

	static int activity_activate(struct led_classdev *led_cdev)
	{
	struct activity_data *activity_data;

	activity_data = kzalloc(sizeof(*activity_data), GFP_KERNEL);
	if (!activity_data)
	return -ENOMEM;

	led_set_trigger_data(led_cdev, activity_data);

	activity_data->led_cdev = led_cdev;
	timer_setup(&activity_data->timer, led_activity_function, 0);
	if (!led_cdev->blink_brightness)
	led_cdev->blink_brightness = led_cdev->max_brightness;
	led_activity_function(&activity_data->timer);
	set_bit(LED_BLINK_SW, &led_cdev->work_flags);

	return 0;
	}

	static void activity_deactivate(struct led_classdev *led_cdev)
	{
	struct activity_data *activity_data = led_get_trigger_data(led_cdev);

	del_timer_sync(&activity_data->timer);
	kfree(activity_data);
	clear_bit(LED_BLINK_SW, &led_cdev->work_flags);
	}

	static struct led_trigger activity_led_trigger = {
	.name = "activity",
	.activate = activity_activate,
	.deactivate = activity_deactivate,
	.groups = activity_led_groups,
	};

	static int activity_reboot_notifier(struct notifier_block *nb,
	unsigned long code, void *unused)
	{
	led_trigger_unregister(&activity_led_trigger);
	return NOTIFY_DONE;
	}

	static int activity_panic_notifier(struct notifier_block *nb,
	unsigned long code, void *unused)
	{
	panic_detected = 1;
	return NOTIFY_DONE;
	}

	static struct notifier_block activity_reboot_nb = {
	.notifier_call = activity_reboot_notifier,
	};

	static struct notifier_block activity_panic_nb = {
	.notifier_call = activity_panic_notifier,
	};

	static int __init activity_init(void)
	{
	int rc = led_trigger_register(&activity_led_trigger);

	if (!rc) {
	atomic_notifier_chain_register(&panic_notifier_list,
	&activity_panic_nb);
	register_reboot_notifier(&activity_reboot_nb);
	}
	return rc;
	}

	static void __exit activity_exit(void)
	{
	unregister_reboot_notifier(&activity_reboot_nb);
	atomic_notifier_chain_unregister(&panic_notifier_list,
	&activity_panic_nb);
	led_trigger_unregister(&activity_led_trigger);
	}

	module_init(activity_init);
	module_exit(activity_exit);

	MODULE_AUTHOR("Willy Tarreau <w@1wt.eu>");
	MODULE_DESCRIPTION("Activity LED trigger");
	MODULE_LICENSE("GPL v2");