[mirror_ubuntu-jammy-kernel.git] / drivers / leds / trigger / ledtrig-activity.c

// 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");
Commit	Line	Data
d2912cb1	1	// SPDX-License-Identifier: GPL-2.0-only
7df4f9a9 WT	2	/*
	3	* Activity LED trigger
	4	*
	5	* Copyright (C) 2017 Willy Tarreau <w@1wt.eu>
	6	* Partially based on Atsushi Nemoto's ledtrig-heartbeat.c.
7df4f9a9	7	*/
033692eb	8
7df4f9a9 WT	9	#include <linux/init.h>
	10	#include <linux/kernel.h>
	11	#include <linux/kernel_stat.h>
	12	#include <linux/leds.h>
	13	#include <linux/module.h>
	14	#include <linux/reboot.h>
	15	#include <linux/sched.h>
	16	#include <linux/slab.h>
	17	#include <linux/timer.h>
	18	#include "../leds.h"
	19
	20	static int panic_detected;
	21
	22	struct activity_data {
	23	struct timer_list timer;
49404665	24	struct led_classdev *led_cdev;
7df4f9a9 WT	25	u64 last_used;
	26	u64 last_boot;
	27	int time_left;
	28	int state;
	29	int invert;
	30	};
	31
49404665	32	static void led_activity_function(struct timer_list *t)
7df4f9a9	33	{
49404665 KC	34	struct activity_data *activity_data = from_timer(activity_data, t,
	35	timer);
	36	struct led_classdev *led_cdev = activity_data->led_cdev;
7df4f9a9 WT	37	unsigned int target;
	38	unsigned int usage;
	39	int delay;
	40	u64 curr_used;
	41	u64 curr_boot;
	42	s32 diff_used;
	43	s32 diff_boot;
	44	int cpus;
	45	int i;
	46
	47	if (test_and_clear_bit(LED_BLINK_BRIGHTNESS_CHANGE, &led_cdev->work_flags))
	48	led_cdev->blink_brightness = led_cdev->new_blink_brightness;
	49
	50	if (unlikely(panic_detected)) {
	51	/* full brightness in case of panic */
	52	led_set_brightness_nosleep(led_cdev, led_cdev->blink_brightness);
	53	return;
	54	}
	55
7df4f9a9 WT	56	cpus = 0;
	57	curr_used = 0;
	58
	59	for_each_possible_cpu(i) {
8688f2fb FW	60	struct kernel_cpustat kcpustat;
	61
	62	kcpustat_cpu_fetch(&kcpustat, i);
	63
	64	curr_used += kcpustat.cpustat[CPUTIME_USER]
	65	+ kcpustat.cpustat[CPUTIME_NICE]
	66	+ kcpustat.cpustat[CPUTIME_SYSTEM]
	67	+ kcpustat.cpustat[CPUTIME_SOFTIRQ]
	68	+ kcpustat.cpustat[CPUTIME_IRQ];
7df4f9a9 WT	69	cpus++;
	70	}
	71
	72	/* We come here every 100ms in the worst case, so that's 100M ns of
	73	* cumulated time. By dividing by 2^16, we get the time resolution
	74	* down to 16us, ensuring we won't overflow 32-bit computations below
	75	* even up to 3k CPUs, while keeping divides cheap on smaller systems.
	76	*/
9285ec4c	77	curr_boot = ktime_get_boottime_ns() * cpus;
7df4f9a9 WT	78	diff_boot = (curr_boot - activity_data->last_boot) >> 16;
	79	diff_used = (curr_used - activity_data->last_used) >> 16;
	80	activity_data->last_boot = curr_boot;
	81	activity_data->last_used = curr_used;
	82
	83	if (diff_boot <= 0 \|\| diff_used < 0)
	84	usage = 0;
	85	else if (diff_used >= diff_boot)
	86	usage = 100;
	87	else
	88	usage = 100 * diff_used / diff_boot;
	89
	90	/*
	91	* Now we know the total boot_time multiplied by the number of CPUs, and
	92	* the total idle+wait time for all CPUs. We'll compare how they evolved
	93	* since last call. The % of overall CPU usage is :
	94	*
	95	* 1 - delta_idle / delta_boot
	96	*
	97	* What we want is that when the CPU usage is zero, the LED must blink
	98	* slowly with very faint flashes that are detectable but not disturbing
	99	* (typically 10ms every second, or 10ms ON, 990ms OFF). Then we want
	100	* blinking frequency to increase up to the point where the load is
	101	* enough to saturate one core in multi-core systems or 50% in single
	102	* core systems. At this point it should reach 10 Hz with a 10/90 duty
	103	* cycle (10ms ON, 90ms OFF). After this point, the blinking frequency
	104	* remains stable (10 Hz) and only the duty cycle increases to report
	105	* the activity, up to the point where we have 90ms ON, 10ms OFF when
	106	* all cores are saturated. It's important that the LED never stays in
	107	* a steady state so that it's easy to distinguish an idle or saturated
	108	* machine from a hung one.
	109	*
	110	* This gives us :
	111	* - a target CPU usage of min(50%, 100%/#CPU) for a 10% duty cycle
	112	* (10ms ON, 90ms OFF)
	113	* - below target :
	114	* ON_ms = 10
	115	* OFF_ms = 90 + (1 - usage/target) * 900
	116	* - above target :
	117	* ON_ms = 10 + (usage-target)/(100%-target) * 80
	118	* OFF_ms = 90 - (usage-target)/(100%-target) * 80
	119	*
	120	* In order to keep a good responsiveness, we cap the sleep time to
	121	* 100 ms and keep track of the sleep time left. This allows us to
	122	* quickly change it if needed.
	123	*/
	124
	125	activity_data->time_left -= 100;
	126	if (activity_data->time_left <= 0) {
	127	activity_data->time_left = 0;
	128	activity_data->state = !activity_data->state;
	129	led_set_brightness_nosleep(led_cdev,
	130	(activity_data->state ^ activity_data->invert) ?
	131	led_cdev->blink_brightness : LED_OFF);
	132	}
	133
	134	target = (cpus > 1) ? (100 / cpus) : 50;
	135
	136	if (usage < target)
	137	delay = activity_data->state ?
	138	10 : /* ON */
	139	990 - 900 * usage / target; /* OFF */
	140	else
	141	delay = activity_data->state ?
142	10 + 80 * (usage - target) / (100 - target) : /* ON */
143	90 - 80 * (usage - target) / (100 - target); /* OFF */
144
145
146	if (!activity_data->time_left \|\| delay <= activity_data->time_left)
147	activity_data->time_left = delay;
148
149	delay = min_t(int, activity_data->time_left, 100);
150	mod_timer(&activity_data->timer, jiffies + msecs_to_jiffies(delay));
151	}
152
153	static ssize_t led_invert_show(struct device *dev,
154	struct device_attribute attr, char buf)
155	{
13d698cb	156	struct activity_data *activity_data = led_trigger_get_drvdata(dev);
7df4f9a9 WT	157
	158	return sprintf(buf, "%u\n", activity_data->invert);
	159	}
	160
	161	static ssize_t led_invert_store(struct device *dev,
	162	struct device_attribute *attr,
	163	const char *buf, size_t size)
	164	{
13d698cb	165	struct activity_data *activity_data = led_trigger_get_drvdata(dev);
7df4f9a9 WT	166	unsigned long state;
	167	int ret;
	168
	169	ret = kstrtoul(buf, 0, &state);
	170	if (ret)
	171	return ret;
	172
	173	activity_data->invert = !!state;
	174
	175	return size;
	176	}
	177
	178	static DEVICE_ATTR(invert, 0644, led_invert_show, led_invert_store);
	179
13d698cb UKK	180	static struct attribute *activity_led_attrs[] = {
	181	&dev_attr_invert.attr,
	182	NULL
	183	};
	184	ATTRIBUTE_GROUPS(activity_led);
	185
2282e125	186	static int activity_activate(struct led_classdev *led_cdev)
7df4f9a9 WT	187	{
7df4f9a9 WT	188	struct activity_data *activity_data;
7df4f9a9 WT	189
	190	activity_data = kzalloc(sizeof(*activity_data), GFP_KERNEL);
	191	if (!activity_data)
13d698cb	192	return -ENOMEM;
7df4f9a9	193
13d698cb	194	led_set_trigger_data(led_cdev, activity_data);
7df4f9a9	195
49404665 KC	196	activity_data->led_cdev = led_cdev;
49404665 KC	197	timer_setup(&activity_data->timer, led_activity_function, 0);
7df4f9a9 WT	198	if (!led_cdev->blink_brightness)
7df4f9a9 WT	199	led_cdev->blink_brightness = led_cdev->max_brightness;
49404665	200	led_activity_function(&activity_data->timer);
7df4f9a9	201	set_bit(LED_BLINK_SW, &led_cdev->work_flags);
2282e125 UKK	202
2282e125 UKK	203	return 0;
7df4f9a9 WT	204	}
	205
	206	static void activity_deactivate(struct led_classdev *led_cdev)
	207	{
13d698cb UKK	208	struct activity_data *activity_data = led_get_trigger_data(led_cdev);
	209
	210	del_timer_sync(&activity_data->timer);
	211	kfree(activity_data);
	212	clear_bit(LED_BLINK_SW, &led_cdev->work_flags);
7df4f9a9 WT	213	}
	214
	215	static struct led_trigger activity_led_trigger = {
	216	.name = "activity",
	217	.activate = activity_activate,
	218	.deactivate = activity_deactivate,
13d698cb	219	.groups = activity_led_groups,
7df4f9a9 WT	220	};
	221
	222	static int activity_reboot_notifier(struct notifier_block *nb,
	223	unsigned long code, void *unused)
	224	{
	225	led_trigger_unregister(&activity_led_trigger);
	226	return NOTIFY_DONE;
	227	}
	228
	229	static int activity_panic_notifier(struct notifier_block *nb,
	230	unsigned long code, void *unused)
	231	{
	232	panic_detected = 1;
	233	return NOTIFY_DONE;
	234	}
	235
	236	static struct notifier_block activity_reboot_nb = {
	237	.notifier_call = activity_reboot_notifier,
	238	};
	239
	240	static struct notifier_block activity_panic_nb = {
	241	.notifier_call = activity_panic_notifier,
	242	};
	243
	244	static int __init activity_init(void)
	245	{
	246	int rc = led_trigger_register(&activity_led_trigger);
	247
	248	if (!rc) {
	249	atomic_notifier_chain_register(&panic_notifier_list,
	250	&activity_panic_nb);
	251	register_reboot_notifier(&activity_reboot_nb);
	252	}
	253	return rc;
	254	}
	255
	256	static void __exit activity_exit(void)
	257	{
	258	unregister_reboot_notifier(&activity_reboot_nb);
	259	atomic_notifier_chain_unregister(&panic_notifier_list,
	260	&activity_panic_nb);
	261	led_trigger_unregister(&activity_led_trigger);
	262	}
	263
	264	module_init(activity_init);
	265	module_exit(activity_exit);
	266
	267	MODULE_AUTHOR("Willy Tarreau <w@1wt.eu>");
	268	MODULE_DESCRIPTION("Activity LED trigger");
033692eb	269	MODULE_LICENSE("GPL v2");