143 lines
3.2 KiB
C
143 lines
3.2 KiB
C
/*
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* ledtrig-cpu.c - LED trigger based on CPU activity
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*
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* This LED trigger will be registered for each possible CPU and named as
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* cpu0, cpu1, cpu2, cpu3, etc.
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*
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* It can be bound to any LED just like other triggers using either a
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* board file or via sysfs interface.
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*
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* An API named ledtrig_cpu is exported for any user, who want to add CPU
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* activity indication in their code
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*
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* Copyright 2011 Linus Walleij <linus.walleij@linaro.org>
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* Copyright 2011 - 2012 Bryan Wu <bryan.wu@canonical.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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*/
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#include <linux/kernel.h>
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#include <linux/init.h>
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#include <linux/slab.h>
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#include <linux/percpu.h>
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#include <linux/syscore_ops.h>
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#include <linux/rwsem.h>
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#include <linux/cpu.h>
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#include "../leds.h"
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#define MAX_NAME_LEN 8
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struct led_trigger_cpu {
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char name[MAX_NAME_LEN];
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struct led_trigger *_trig;
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};
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static DEFINE_PER_CPU(struct led_trigger_cpu, cpu_trig);
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/**
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* ledtrig_cpu - emit a CPU event as a trigger
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* @evt: CPU event to be emitted
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*
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* Emit a CPU event on a CPU core, which will trigger a
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* binded LED to turn on or turn off.
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*/
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void ledtrig_cpu(enum cpu_led_event ledevt)
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{
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struct led_trigger_cpu *trig = this_cpu_ptr(&cpu_trig);
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/* Locate the correct CPU LED */
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switch (ledevt) {
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case CPU_LED_IDLE_END:
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case CPU_LED_START:
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/* Will turn the LED on, max brightness */
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led_trigger_event(trig->_trig, LED_FULL);
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break;
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case CPU_LED_IDLE_START:
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case CPU_LED_STOP:
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case CPU_LED_HALTED:
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/* Will turn the LED off */
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led_trigger_event(trig->_trig, LED_OFF);
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break;
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default:
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/* Will leave the LED as it is */
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break;
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}
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}
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EXPORT_SYMBOL(ledtrig_cpu);
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static int ledtrig_cpu_syscore_suspend(void)
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{
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ledtrig_cpu(CPU_LED_STOP);
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return 0;
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}
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static void ledtrig_cpu_syscore_resume(void)
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{
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ledtrig_cpu(CPU_LED_START);
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}
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static void ledtrig_cpu_syscore_shutdown(void)
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{
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ledtrig_cpu(CPU_LED_HALTED);
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}
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static struct syscore_ops ledtrig_cpu_syscore_ops = {
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.shutdown = ledtrig_cpu_syscore_shutdown,
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.suspend = ledtrig_cpu_syscore_suspend,
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.resume = ledtrig_cpu_syscore_resume,
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};
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static int ledtrig_cpu_notify(struct notifier_block *self,
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unsigned long action, void *hcpu)
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{
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switch (action & ~CPU_TASKS_FROZEN) {
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case CPU_STARTING:
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ledtrig_cpu(CPU_LED_START);
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break;
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case CPU_DYING:
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ledtrig_cpu(CPU_LED_STOP);
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break;
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}
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return NOTIFY_OK;
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}
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static struct notifier_block ledtrig_cpu_nb = {
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.notifier_call = ledtrig_cpu_notify,
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};
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static int __init ledtrig_cpu_init(void)
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{
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int cpu;
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/* Supports up to 9999 cpu cores */
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BUILD_BUG_ON(CONFIG_NR_CPUS > 9999);
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/*
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* Registering CPU led trigger for each CPU core here
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* ignores CPU hotplug, but after this CPU hotplug works
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* fine with this trigger.
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*/
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for_each_possible_cpu(cpu) {
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struct led_trigger_cpu *trig = &per_cpu(cpu_trig, cpu);
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snprintf(trig->name, MAX_NAME_LEN, "cpu%d", cpu);
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led_trigger_register_simple(trig->name, &trig->_trig);
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}
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register_syscore_ops(&ledtrig_cpu_syscore_ops);
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register_cpu_notifier(&ledtrig_cpu_nb);
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pr_info("ledtrig-cpu: registered to indicate activity on CPUs\n");
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return 0;
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}
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device_initcall(ledtrig_cpu_init);
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