--- /dev/null
+/*
+ * 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");
projects / platform / kernel / linux-starfive.git / commitdiff