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1// SPDX-License-Identifier: GPL-2.0-only2/*3 * ledtrig-cpu.c - LED trigger based on CPU activity4 *5 * This LED trigger will be registered for first 8 CPUs and named6 * as cpu0..cpu7. There's additional trigger called cpu that7 * is on when any CPU is active.8 *9 * If you want support for arbitrary number of CPUs, make it one trigger,10 * with additional sysfs file selecting which CPU to watch.11 *12 * It can be bound to any LED just like other triggers using either a13 * board file or via sysfs interface.14 *15 * An API named ledtrig_cpu is exported for any user, who want to add CPU16 * activity indication in their code.17 *18 * Copyright 2011 Linus Walleij <linus.walleij@linaro.org>19 * Copyright 2011 - 2012 Bryan Wu <bryan.wu@canonical.com>20 */21 22#include <linux/kernel.h>23#include <linux/init.h>24#include <linux/slab.h>25#include <linux/percpu.h>26#include <linux/syscore_ops.h>27#include <linux/rwsem.h>28#include <linux/cpu.h>29#include "../leds.h"30 31#define MAX_NAME_LEN 832 33struct led_trigger_cpu {34 bool is_active;35 char name[MAX_NAME_LEN];36 struct led_trigger *_trig;37};38 39static DEFINE_PER_CPU(struct led_trigger_cpu, cpu_trig);40 41static struct led_trigger *trig_cpu_all;42static atomic_t num_active_cpus = ATOMIC_INIT(0);43 44/**45 * ledtrig_cpu - emit a CPU event as a trigger46 * @ledevt: CPU event to be emitted47 *48 * Emit a CPU event on a CPU core, which will trigger a49 * bound LED to turn on or turn off.50 */51void ledtrig_cpu(enum cpu_led_event ledevt)52{53 struct led_trigger_cpu *trig = this_cpu_ptr(&cpu_trig);54 bool is_active = trig->is_active;55 56 /* Locate the correct CPU LED */57 switch (ledevt) {58 case CPU_LED_IDLE_END:59 case CPU_LED_START:60 /* Will turn the LED on, max brightness */61 is_active = true;62 break;63 64 case CPU_LED_IDLE_START:65 case CPU_LED_STOP:66 case CPU_LED_HALTED:67 /* Will turn the LED off */68 is_active = false;69 break;70 71 default:72 /* Will leave the LED as it is */73 break;74 }75 76 if (is_active != trig->is_active) {77 unsigned int active_cpus;78 unsigned int total_cpus;79 80 /* Update trigger state */81 trig->is_active = is_active;82 atomic_add(is_active ? 1 : -1, &num_active_cpus);83 active_cpus = atomic_read(&num_active_cpus);84 total_cpus = num_present_cpus();85 86 led_trigger_event(trig->_trig,87 is_active ? LED_FULL : LED_OFF);88 89 90 led_trigger_event(trig_cpu_all,91 DIV_ROUND_UP(LED_FULL * active_cpus, total_cpus));92 93 }94}95EXPORT_SYMBOL(ledtrig_cpu);96 97static int ledtrig_cpu_syscore_suspend(void)98{99 ledtrig_cpu(CPU_LED_STOP);100 return 0;101}102 103static void ledtrig_cpu_syscore_resume(void)104{105 ledtrig_cpu(CPU_LED_START);106}107 108static void ledtrig_cpu_syscore_shutdown(void)109{110 ledtrig_cpu(CPU_LED_HALTED);111}112 113static struct syscore_ops ledtrig_cpu_syscore_ops = {114 .shutdown = ledtrig_cpu_syscore_shutdown,115 .suspend = ledtrig_cpu_syscore_suspend,116 .resume = ledtrig_cpu_syscore_resume,117};118 119static int ledtrig_online_cpu(unsigned int cpu)120{121 ledtrig_cpu(CPU_LED_START);122 return 0;123}124 125static int ledtrig_prepare_down_cpu(unsigned int cpu)126{127 ledtrig_cpu(CPU_LED_STOP);128 return 0;129}130 131static int __init ledtrig_cpu_init(void)132{133 unsigned int cpu;134 int ret;135 136 /* Supports up to 9999 cpu cores */137 BUILD_BUG_ON(CONFIG_NR_CPUS > 9999);138 139 /*140 * Registering a trigger for all CPUs.141 */142 led_trigger_register_simple("cpu", &trig_cpu_all);143 144 /*145 * Registering CPU led trigger for each CPU core here146 * ignores CPU hotplug, but after this CPU hotplug works147 * fine with this trigger.148 */149 for_each_possible_cpu(cpu) {150 struct led_trigger_cpu *trig = &per_cpu(cpu_trig, cpu);151 152 if (cpu >= 8)153 continue;154 155 snprintf(trig->name, MAX_NAME_LEN, "cpu%u", cpu);156 157 led_trigger_register_simple(trig->name, &trig->_trig);158 }159 160 register_syscore_ops(&ledtrig_cpu_syscore_ops);161 162 ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "leds/trigger:starting",163 ledtrig_online_cpu, ledtrig_prepare_down_cpu);164 if (ret < 0)165 pr_err("CPU hotplug notifier for ledtrig-cpu could not be registered: %d\n",166 ret);167 168 pr_info("ledtrig-cpu: registered to indicate activity on CPUs\n");169 170 return 0;171}172device_initcall(ledtrig_cpu_init);173