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 <linux/cpu.h>
30 #include "../leds.h"
31
32 #define MAX_NAME_LEN 8
33
34 struct led_trigger_cpu {
35 char name[MAX_NAME_LEN];
36 struct led_trigger *_trig;
37 };
38
39 static DEFINE_PER_CPU(struct led_trigger_cpu, cpu_trig);
40
41 /**
42 * ledtrig_cpu - emit a CPU event as a trigger
43 * @evt: CPU event to be emitted
44 *
45 * Emit a CPU event on a CPU core, which will trigger a
46 * binded LED to turn on or turn off.
47 */
ledtrig_cpu(enum cpu_led_event ledevt)48 void ledtrig_cpu(enum cpu_led_event ledevt)
49 {
50 struct led_trigger_cpu *trig = this_cpu_ptr(&cpu_trig);
51
52 /* Locate the correct CPU LED */
53 switch (ledevt) {
54 case CPU_LED_IDLE_END:
55 case CPU_LED_START:
56 /* Will turn the LED on, max brightness */
57 led_trigger_event(trig->_trig, LED_FULL);
58 break;
59
60 case CPU_LED_IDLE_START:
61 case CPU_LED_STOP:
62 case CPU_LED_HALTED:
63 /* Will turn the LED off */
64 led_trigger_event(trig->_trig, LED_OFF);
65 break;
66
67 default:
68 /* Will leave the LED as it is */
69 break;
70 }
71 }
72 EXPORT_SYMBOL(ledtrig_cpu);
73
ledtrig_cpu_syscore_suspend(void)74 static int ledtrig_cpu_syscore_suspend(void)
75 {
76 ledtrig_cpu(CPU_LED_STOP);
77 return 0;
78 }
79
ledtrig_cpu_syscore_resume(void)80 static void ledtrig_cpu_syscore_resume(void)
81 {
82 ledtrig_cpu(CPU_LED_START);
83 }
84
ledtrig_cpu_syscore_shutdown(void)85 static void ledtrig_cpu_syscore_shutdown(void)
86 {
87 ledtrig_cpu(CPU_LED_HALTED);
88 }
89
90 static struct syscore_ops ledtrig_cpu_syscore_ops = {
91 .shutdown = ledtrig_cpu_syscore_shutdown,
92 .suspend = ledtrig_cpu_syscore_suspend,
93 .resume = ledtrig_cpu_syscore_resume,
94 };
95
ledtrig_cpu_notify(struct notifier_block * self,unsigned long action,void * hcpu)96 static int ledtrig_cpu_notify(struct notifier_block *self,
97 unsigned long action, void *hcpu)
98 {
99 switch (action & ~CPU_TASKS_FROZEN) {
100 case CPU_STARTING:
101 ledtrig_cpu(CPU_LED_START);
102 break;
103 case CPU_DYING:
104 ledtrig_cpu(CPU_LED_STOP);
105 break;
106 }
107
108 return NOTIFY_OK;
109 }
110
111
112 static struct notifier_block ledtrig_cpu_nb = {
113 .notifier_call = ledtrig_cpu_notify,
114 };
115
ledtrig_cpu_init(void)116 static int __init ledtrig_cpu_init(void)
117 {
118 int cpu;
119
120 /* Supports up to 9999 cpu cores */
121 BUILD_BUG_ON(CONFIG_NR_CPUS > 9999);
122
123 /*
124 * Registering CPU led trigger for each CPU core here
125 * ignores CPU hotplug, but after this CPU hotplug works
126 * fine with this trigger.
127 */
128 for_each_possible_cpu(cpu) {
129 struct led_trigger_cpu *trig = &per_cpu(cpu_trig, cpu);
130
131 snprintf(trig->name, MAX_NAME_LEN, "cpu%d", cpu);
132
133 led_trigger_register_simple(trig->name, &trig->_trig);
134 }
135
136 register_syscore_ops(&ledtrig_cpu_syscore_ops);
137 register_cpu_notifier(&ledtrig_cpu_nb);
138
139 pr_info("ledtrig-cpu: registered to indicate activity on CPUs\n");
140
141 return 0;
142 }
143 module_init(ledtrig_cpu_init);
144
ledtrig_cpu_exit(void)145 static void __exit ledtrig_cpu_exit(void)
146 {
147 int cpu;
148
149 unregister_cpu_notifier(&ledtrig_cpu_nb);
150
151 for_each_possible_cpu(cpu) {
152 struct led_trigger_cpu *trig = &per_cpu(cpu_trig, cpu);
153
154 led_trigger_unregister_simple(trig->_trig);
155 trig->_trig = NULL;
156 memset(trig->name, 0, MAX_NAME_LEN);
157 }
158
159 unregister_syscore_ops(&ledtrig_cpu_syscore_ops);
160 }
161 module_exit(ledtrig_cpu_exit);
162
163 MODULE_AUTHOR("Linus Walleij <linus.walleij@linaro.org>");
164 MODULE_AUTHOR("Bryan Wu <bryan.wu@canonical.com>");
165 MODULE_DESCRIPTION("CPU LED trigger");
166 MODULE_LICENSE("GPL");
167