diff options
Diffstat (limited to 'drivers/leds/trigger/ledtrig-activity.c')
| -rw-r--r-- | drivers/leds/trigger/ledtrig-activity.c | 270 |
1 files changed, 270 insertions, 0 deletions
diff --git a/drivers/leds/trigger/ledtrig-activity.c b/drivers/leds/trigger/ledtrig-activity.c new file mode 100644 index 000000000..30bc9df03 --- /dev/null +++ b/drivers/leds/trigger/ledtrig-activity.c @@ -0,0 +1,270 @@ +// 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/panic_notifier.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"); |