Orange Pi5 kernel

// 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");