ledtrig-cpu.c
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/*
* ledtrig-cpu.c - LED trigger based on CPU activity
*
* This LED trigger will be registered for each possible CPU and named as
* cpu0, cpu1, cpu2, cpu3, etc.
*
* 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 <linus.walleij@linaro.org>
* Copyright 2011 - 2012 Bryan Wu <bryan.wu@canonical.com>
*
* 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/module.h>
#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 "../leds.h"
#define MAX_NAME_LEN 8
struct led_trigger_cpu {
char name[MAX_NAME_LEN];
struct led_trigger *_trig;
};
static DEFINE_PER_CPU(struct led_trigger_cpu, cpu_trig);
/**
* ledtrig_cpu - emit a CPU event as a trigger
* @evt: CPU event to be emitted
*
* Emit a CPU event on a CPU core, which will trigger a
* binded LED to turn on or turn off.
*/
void ledtrig_cpu(enum cpu_led_event ledevt)
{
struct led_trigger_cpu *trig = &__get_cpu_var(cpu_trig);
/* Locate the correct CPU LED */
switch (ledevt) {
case CPU_LED_IDLE_END:
case CPU_LED_START:
/* Will turn the LED on, max brightness */
led_trigger_event(trig->_trig, LED_FULL);
break;
case CPU_LED_IDLE_START:
case CPU_LED_STOP:
case CPU_LED_HALTED:
/* Will turn the LED off */
led_trigger_event(trig->_trig, LED_OFF);
break;
default:
/* Will leave the LED as it is */
break;
}
}
EXPORT_SYMBOL(ledtrig_cpu);
static int ledtrig_cpu_syscore_suspend(void)
{
ledtrig_cpu(CPU_LED_STOP);
return 0;
}
static void ledtrig_cpu_syscore_resume(void)
{
ledtrig_cpu(CPU_LED_START);
}
static void ledtrig_cpu_syscore_shutdown(void)
{
ledtrig_cpu(CPU_LED_HALTED);
}
static struct syscore_ops ledtrig_cpu_syscore_ops = {
.shutdown = ledtrig_cpu_syscore_shutdown,
.suspend = ledtrig_cpu_syscore_suspend,
.resume = ledtrig_cpu_syscore_resume,
};
static int __init ledtrig_cpu_init(void)
{
int cpu;
/* Supports up to 9999 cpu cores */
BUILD_BUG_ON(CONFIG_NR_CPUS > 9999);
/*
* Registering CPU led trigger for each CPU core here
* ignores CPU hotplug, but after this CPU hotplug works
* fine with this trigger.
*/
for_each_possible_cpu(cpu) {
struct led_trigger_cpu *trig = &per_cpu(cpu_trig, cpu);
snprintf(trig->name, MAX_NAME_LEN, "cpu%d", cpu);
led_trigger_register_simple(trig->name, &trig->_trig);
}
register_syscore_ops(&ledtrig_cpu_syscore_ops);
pr_info("ledtrig-cpu: registered to indicate activity on CPUs\n");
return 0;
}
module_init(ledtrig_cpu_init);
static void __exit ledtrig_cpu_exit(void)
{
int cpu;
for_each_possible_cpu(cpu) {
struct led_trigger_cpu *trig = &per_cpu(cpu_trig, cpu);
led_trigger_unregister_simple(trig->_trig);
trig->_trig = NULL;
memset(trig->name, 0, MAX_NAME_LEN);
}
unregister_syscore_ops(&ledtrig_cpu_syscore_ops);
}
module_exit(ledtrig_cpu_exit);
MODULE_AUTHOR("Linus Walleij <linus.walleij@linaro.org>");
MODULE_AUTHOR("Bryan Wu <bryan.wu@canonical.com>");
MODULE_DESCRIPTION("CPU LED trigger");
MODULE_LICENSE("GPL");