1 /*
2 * ledtrig-cpu.c - LED trigger based on CPU activity
3 *
4 * This LED trigger will be registered for each possible CPU and named as
5 * cpu0, cpu1, cpu2, cpu3, etc.
6 *
7 * It can be bound to any LED just like other triggers using either a
8 * board file or via sysfs interface.
9 *
10 * An API named ledtrig_cpu is exported for any user, who want to add CPU
11 * activity indication in their code
12 *
13 * Copyright 2011 Linus Walleij <linus.walleij@linaro.org>
14 * Copyright 2011 - 2012 Bryan Wu <bryan.wu@canonical.com>
15 *
16 * This program is free software; you can redistribute it and/or modify
17 * it under the terms of the GNU General Public License version 2 as
18 * published by the Free Software Foundation.
19 *
20 */
21
22 #include <linux/module.h>
23 #include <linux/kernel.h>
24 #include <linux/init.h>
25 #include <linux/slab.h>
26 #include <linux/percpu.h>
27 #include <linux/syscore_ops.h>
28 #include <linux/rwsem.h>
29 #include "../leds.h"
30
31 #define MAX_NAME_LEN 8
32
33 struct led_trigger_cpu {
34 char name[MAX_NAME_LEN];
35 struct led_trigger *_trig;
36 };
37
38 static DEFINE_PER_CPU(struct led_trigger_cpu, cpu_trig);
39
40 /**
41 * ledtrig_cpu - emit a CPU event as a trigger
42 * @evt: CPU event to be emitted
43 *
44 * Emit a CPU event on a CPU core, which will trigger a
45 * binded LED to turn on or turn off.
46 */
ledtrig_cpu(enum cpu_led_event ledevt)47 void ledtrig_cpu(enum cpu_led_event ledevt)
48 {
49 struct led_trigger_cpu *trig = &__get_cpu_var(cpu_trig);
50
51 /* Locate the correct CPU LED */
52 switch (ledevt) {
53 case CPU_LED_IDLE_END:
54 case CPU_LED_START:
55 /* Will turn the LED on, max brightness */
56 led_trigger_event(trig->_trig, LED_FULL);
57 break;
58
59 case CPU_LED_IDLE_START:
60 case CPU_LED_STOP:
61 case CPU_LED_HALTED:
62 /* Will turn the LED off */
63 led_trigger_event(trig->_trig, LED_OFF);
64 break;
65
66 default:
67 /* Will leave the LED as it is */
68 break;
69 }
70 }
71 EXPORT_SYMBOL(ledtrig_cpu);
72
ledtrig_cpu_syscore_suspend(void)73 static int ledtrig_cpu_syscore_suspend(void)
74 {
75 ledtrig_cpu(CPU_LED_STOP);
76 return 0;
77 }
78
ledtrig_cpu_syscore_resume(void)79 static void ledtrig_cpu_syscore_resume(void)
80 {
81 ledtrig_cpu(CPU_LED_START);
82 }
83
ledtrig_cpu_syscore_shutdown(void)84 static void ledtrig_cpu_syscore_shutdown(void)
85 {
86 ledtrig_cpu(CPU_LED_HALTED);
87 }
88
89 static struct syscore_ops ledtrig_cpu_syscore_ops = {
90 .shutdown = ledtrig_cpu_syscore_shutdown,
91 .suspend = ledtrig_cpu_syscore_suspend,
92 .resume = ledtrig_cpu_syscore_resume,
93 };
94
ledtrig_cpu_init(void)95 static int __init ledtrig_cpu_init(void)
96 {
97 int cpu;
98
99 /* Supports up to 9999 cpu cores */
100 BUILD_BUG_ON(CONFIG_NR_CPUS > 9999);
101
102 /*
103 * Registering CPU led trigger for each CPU core here
104 * ignores CPU hotplug, but after this CPU hotplug works
105 * fine with this trigger.
106 */
107 for_each_possible_cpu(cpu) {
108 struct led_trigger_cpu *trig = &per_cpu(cpu_trig, cpu);
109
110 snprintf(trig->name, MAX_NAME_LEN, "cpu%d", cpu);
111
112 led_trigger_register_simple(trig->name, &trig->_trig);
113 }
114
115 register_syscore_ops(&ledtrig_cpu_syscore_ops);
116
117 pr_info("ledtrig-cpu: registered to indicate activity on CPUs\n");
118
119 return 0;
120 }
121 module_init(ledtrig_cpu_init);
122
ledtrig_cpu_exit(void)123 static void __exit ledtrig_cpu_exit(void)
124 {
125 int cpu;
126
127 for_each_possible_cpu(cpu) {
128 struct led_trigger_cpu *trig = &per_cpu(cpu_trig, cpu);
129
130 led_trigger_unregister_simple(trig->_trig);
131 trig->_trig = NULL;
132 memset(trig->name, 0, MAX_NAME_LEN);
133 }
134
135 unregister_syscore_ops(&ledtrig_cpu_syscore_ops);
136 }
137 module_exit(ledtrig_cpu_exit);
138
139 MODULE_AUTHOR("Linus Walleij <linus.walleij@linaro.org>");
140 MODULE_AUTHOR("Bryan Wu <bryan.wu@canonical.com>");
141 MODULE_DESCRIPTION("CPU LED trigger");
142 MODULE_LICENSE("GPL");
143