linux/drivers/leds/trigger/ledtrig-cpu.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * ledtrig-cpu.c - LED trigger based on CPU activity
 *
 * This LED trigger will be registered for first 8 CPUs and named
 * as cpu0..cpu7. There's additional trigger called cpu that
 * is on when any CPU is active.
 *
 * If you want support for arbitrary number of CPUs, make it one trigger,
 * with additional sysfs file selecting which CPU to watch.
 *
 * It can be bound to any LED just like other triggers using either a
 * board file or via sysfs interface.
 *
 * An API named ledtrig_cpu is exported for any user, who want to add CPU
 * activity indication in their code.
 *
 * Copyright 2011 Linus Walleij <[email protected]>
 * Copyright 2011 - 2012 Bryan Wu <[email protected]>
 */

#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/percpu.h>
#include <linux/syscore_ops.h>
#include <linux/rwsem.h>
#include <linux/cpu.h>
#include "../leds.h"

#define MAX_NAME_LEN …

struct led_trigger_cpu { … };

static DEFINE_PER_CPU(struct led_trigger_cpu, cpu_trig);

static struct led_trigger *trig_cpu_all;
static atomic_t num_active_cpus = …;

/**
 * ledtrig_cpu - emit a CPU event as a trigger
 * @ledevt: CPU event to be emitted
 *
 * Emit a CPU event on a CPU core, which will trigger a
 * bound LED to turn on or turn off.
 */
void ledtrig_cpu(enum cpu_led_event ledevt)
{ … }
EXPORT_SYMBOL(…);

static int ledtrig_cpu_syscore_suspend(void)
{ … }

static void ledtrig_cpu_syscore_resume(void)
{ … }

static void ledtrig_cpu_syscore_shutdown(void)
{ … }

static struct syscore_ops ledtrig_cpu_syscore_ops = …;

static int ledtrig_online_cpu(unsigned int cpu)
{ … }

static int ledtrig_prepare_down_cpu(unsigned int cpu)
{ … }

static int __init ledtrig_cpu_init(void)
{ … }
device_initcall(ledtrig_cpu_init);