leds/trigger/ledtrig-cpu.c

1 // SPDX-License-Identifier: GPL-2.0-only
3  * ledtrig-cpu.c - LED trigger based on CPU activity
5  * This LED trigger will be registered for first 8 CPUs and named
12  * It can be bound to any LED just like other triggers using either a
19  * Copyright 2011 - 2012 Bryan Wu <bryan.wu@canonical.com>
31 #define MAX_NAME_LEN	8
45  * ledtrig_cpu - emit a CPU event as a trigger
49  * bound LED to turn on or turn off.
54 	bool is_active = trig->is_active;  in ledtrig_cpu()
56 	/* Locate the correct CPU LED */  in ledtrig_cpu()
60 		/* Will turn the LED on, max brightness */  in ledtrig_cpu()
67 		/* Will turn the LED off */  in ledtrig_cpu()
72 		/* Will leave the LED as it is */  in ledtrig_cpu()
76 	if (is_active != trig->is_active) {  in ledtrig_cpu()
81 		trig->is_active = is_active;  in ledtrig_cpu()
82 		atomic_add(is_active ? 1 : -1, &num_active_cpus);  in ledtrig_cpu()
86 		led_trigger_event(trig->_trig,  in ledtrig_cpu()
145 	 * Registering CPU led trigger for each CPU core here  in ledtrig_cpu_init()
152 		if (cpu >= 8)  in ledtrig_cpu_init()
155 		snprintf(trig->name, MAX_NAME_LEN, "cpu%d", cpu);  in ledtrig_cpu_init()
157 		led_trigger_register_simple(trig->name, &trig->_trig);  in ledtrig_cpu_init()
165 		pr_err("CPU hotplug notifier for ledtrig-cpu could not be registered: %d\n",  in ledtrig_cpu_init()
168 	pr_info("ledtrig-cpu: registered to indicate activity on CPUs\n");  in ledtrig_cpu_init()