170 lines
3.9 KiB
C
170 lines
3.9 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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bool is_active;
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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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static struct led_trigger *trig_cpu_all;
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static atomic_t num_active_cpus = ATOMIC_INIT(0);
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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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* bound 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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bool is_active = trig->is_active;
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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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is_active = true;
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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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is_active = false;
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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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if (is_active != trig->is_active) {
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unsigned int active_cpus;
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unsigned int total_cpus;
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/* Update trigger state */
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trig->is_active = is_active;
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atomic_add(is_active ? 1 : -1, &num_active_cpus);
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active_cpus = atomic_read(&num_active_cpus);
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total_cpus = num_present_cpus();
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led_trigger_event(trig->_trig,
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is_active ? LED_FULL : LED_OFF);
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led_trigger_event(trig_cpu_all,
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DIV_ROUND_UP(LED_FULL * active_cpus, total_cpus));
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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_online_cpu(unsigned int cpu)
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{
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ledtrig_cpu(CPU_LED_START);
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return 0;
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}
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static int ledtrig_prepare_down_cpu(unsigned int cpu)
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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 int __init ledtrig_cpu_init(void)
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{
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int cpu;
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int ret;
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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 a trigger for all CPUs.
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*/
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led_trigger_register_simple("cpu", &trig_cpu_all);
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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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ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "leds/trigger:starting",
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ledtrig_online_cpu, ledtrig_prepare_down_cpu);
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if (ret < 0)
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pr_err("CPU hotplug notifier for ledtrig-cpu could not be registered: %d\n",
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ret);
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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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