// 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 * @ledevt: 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 *data){	ledtrig_cpu(CPU_LED_STOP);	return 0;} static void ledtrig_cpu_syscore_resume(void *data){	ledtrig_cpu(CPU_LED_START);} static void ledtrig_cpu_syscore_shutdown(void *data){	ledtrig_cpu(CPU_LED_HALTED);} static const struct syscore_ops ledtrig_cpu_syscore_ops = {	.shutdown	= ledtrig_cpu_syscore_shutdown,	.suspend	= ledtrig_cpu_syscore_suspend,	.resume		= ledtrig_cpu_syscore_resume,}; static struct syscore ledtrig_cpu_syscore = {	.ops = &ledtrig_cpu_syscore_ops,}; 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){	unsigned 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%u", cpu); 		led_trigger_register_simple(trig->name, &trig->_trig);	} 	register_syscore(&ledtrig_cpu_syscore); 	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);