leds: ledtrig-activity: Add a system activity LED trigger (7df4f9a9) · Commits · 戴 / test

drivers/leds/trigger/Kconfig

+9 −0

Original line number	Diff line number	Diff line
		@@ -77,6 +77,15 @@ config LEDS_TRIGGER_CPU

		If unsure, say N.

		config LEDS_TRIGGER_ACTIVITY
		tristate "LED activity Trigger"
		depends on LEDS_TRIGGERS
		help
		This allows LEDs to be controlled by a immediate CPU usage.
		The flash frequency and duty cycle varies from faint flashes to
		intense brightness depending on the instant CPU load.
		If unsure, say N.

		config LEDS_TRIGGER_GPIO
		tristate "LED GPIO Trigger"
		depends on LEDS_TRIGGERS

drivers/leds/trigger/Makefile

+1 −0

Original line number	Diff line number	Diff line
		@@ -6,6 +6,7 @@ obj-$(CONFIG_LEDS_TRIGGER_HEARTBEAT) += ledtrig-heartbeat.o
		obj-$(CONFIG_LEDS_TRIGGER_BACKLIGHT) += ledtrig-backlight.o
		obj-$(CONFIG_LEDS_TRIGGER_GPIO) += ledtrig-gpio.o
		obj-$(CONFIG_LEDS_TRIGGER_CPU) += ledtrig-cpu.o
		obj-$(CONFIG_LEDS_TRIGGER_ACTIVITY) += ledtrig-activity.o
		obj-$(CONFIG_LEDS_TRIGGER_DEFAULT_ON) += ledtrig-default-on.o
		obj-$(CONFIG_LEDS_TRIGGER_TRANSIENT) += ledtrig-transient.o
		obj-$(CONFIG_LEDS_TRIGGER_CAMERA) += ledtrig-camera.o

drivers/leds/trigger/ledtrig-activity.c

0 → 100644

+273 −0

Original line number	Diff line number	Diff line
		/*
		* Activity LED trigger
		*
		* Copyright (C) 2017 Willy Tarreau <w@1wt.eu>
		* Partially based on Atsushi Nemoto's ledtrig-heartbeat.c.
		*
		* This program is free software; you can redistribute it and/or modify
		* it under the terms of the GNU General Public License version 2 as
		* published by the Free Software Foundation.
		*
		*/
		#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;
		u64 last_used;
		u64 last_boot;
		int time_left;
		int state;
		int invert;
		};

		static void led_activity_function(unsigned long data)
		{
		struct led_classdev led_cdev = (struct led_classdev )data;
		struct activity_data *activity_data = led_cdev->trigger_data;
		struct timespec boot_time;
		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;
		}

		get_monotonic_boottime(&boot_time);

		cpus = 0;
		curr_used = 0;

		for_each_possible_cpu(i) {
		curr_used += kcpustat_cpu(i).cpustat[CPUTIME_USER]
		+ kcpustat_cpu(i).cpustat[CPUTIME_NICE]
		+ kcpustat_cpu(i).cpustat[CPUTIME_SYSTEM]
		+ kcpustat_cpu(i).cpustat[CPUTIME_SOFTIRQ]
		+ kcpustat_cpu(i).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 = timespec_to_ns(&boot_time) * 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 led_classdev *led_cdev = dev_get_drvdata(dev);
		struct activity_data *activity_data = led_cdev->trigger_data;

		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 led_classdev *led_cdev = dev_get_drvdata(dev);
		struct activity_data *activity_data = led_cdev->trigger_data;
		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 void activity_activate(struct led_classdev *led_cdev)
		{
		struct activity_data *activity_data;
		int rc;

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

		led_cdev->trigger_data = activity_data;
		rc = device_create_file(led_cdev->dev, &dev_attr_invert);
		if (rc) {
		kfree(led_cdev->trigger_data);
		return;
		}

		setup_timer(&activity_data->timer,
		led_activity_function, (unsigned long)led_cdev);
		if (!led_cdev->blink_brightness)
		led_cdev->blink_brightness = led_cdev->max_brightness;
		led_activity_function(activity_data->timer.data);
		set_bit(LED_BLINK_SW, &led_cdev->work_flags);
		led_cdev->activated = true;
		}

		static void activity_deactivate(struct led_classdev *led_cdev)
		{
		struct activity_data *activity_data = led_cdev->trigger_data;

		if (led_cdev->activated) {
		del_timer_sync(&activity_data->timer);
		device_remove_file(led_cdev->dev, &dev_attr_invert);
		kfree(activity_data);
		clear_bit(LED_BLINK_SW, &led_cdev->work_flags);
		led_cdev->activated = false;
		}
		}

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

		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");

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