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// 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 <linus.walleij@linaro.org>
* Copyright 2011 - 2012 Bryan Wu <bryan.wu@canonical.com>
*/
#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 8
struct led_trigger_cpu {
bool is_active;
char name[MAX_NAME_LEN];
struct led_trigger *_trig;
};
static DEFINE_PER_CPU(struct led_trigger_cpu, cpu_trig);
static struct led_trigger *trig_cpu_all;
static atomic_t num_active_cpus = ATOMIC_INIT(0);
/**
* 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
* bound LED to turn on or turn off.
*/
void ledtrig_cpu(enum cpu_led_event ledevt)
{
struct led_trigger_cpu *trig = this_cpu_ptr(&cpu_trig);
bool is_active = trig->is_active;
/* Locate the correct CPU LED */
switch (ledevt) {
case CPU_LED_IDLE_END:
case CPU_LED_START:
/* Will turn the LED on, max brightness */
is_active = true;
break;
case CPU_LED_IDLE_START:
case CPU_LED_STOP:
case CPU_LED_HALTED:
/* Will turn the LED off */
is_active = false;
break;
default:
/* Will leave the LED as it is */
break;
}
if (is_active != trig->is_active) {
unsigned int active_cpus;
unsigned int total_cpus;
/* Update trigger state */
trig->is_active = is_active;
atomic_add(is_active ? 1 : -1, &num_active_cpus);
active_cpus = atomic_read(&num_active_cpus);
total_cpus = num_present_cpus();
led_trigger_event(trig->_trig,
is_active ? LED_FULL : LED_OFF);
led_trigger_event(trig_cpu_all,
DIV_ROUND_UP(LED_FULL * active_cpus, total_cpus));
}
}
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 ledtrig_online_cpu(unsigned int cpu)
{
ledtrig_cpu(CPU_LED_START);
return 0;
}
static int ledtrig_prepare_down_cpu(unsigned int cpu)
{
ledtrig_cpu(CPU_LED_STOP);
return 0;
}
static int __init ledtrig_cpu_init(void)
{
int cpu;
int ret;
/* Supports up to 9999 cpu cores */
BUILD_BUG_ON(CONFIG_NR_CPUS > 9999);
/*
* Registering a trigger for all CPUs.
*/
led_trigger_register_simple("cpu", &trig_cpu_all);
/*
* 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);
if (cpu >= 8)
continue;
snprintf(trig->name, MAX_NAME_LEN, "cpu%d", cpu);
led_trigger_register_simple(trig->name, &trig->_trig);
}
register_syscore_ops(&ledtrig_cpu_syscore_ops);
ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "leds/trigger:starting",
ledtrig_online_cpu, ledtrig_prepare_down_cpu);
if (ret < 0)
pr_err("CPU hotplug notifier for ledtrig-cpu could not be registered: %d\n",
ret);
pr_info("ledtrig-cpu: registered to indicate activity on CPUs\n");
return 0;
}
device_initcall(ledtrig_cpu_init);
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