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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * ledtrig-cpu.c - LED trigger based on CPU activity
4 *
5 * This LED trigger will be registered for first 8 CPUs and named
6 * as cpu0..cpu7. There's additional trigger called cpu that
7 * 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 a
13 * board file or via sysfs interface.
14 *
15 * An API named ledtrig_cpu is exported for any user, who want to add CPU
16 * 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 8
32
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 trigger
46 * @ledevt: CPU event to be emitted
47 *
48 * Emit a CPU event on a CPU core, which will trigger a
49 * 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 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 here
146 * ignores CPU hotplug, but after this CPU hotplug works
147 * 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%d", 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);
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
34struct led_trigger_cpu {
35 char name[MAX_NAME_LEN];
36 struct led_trigger *_trig;
37};
38
39static 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 */
48void ledtrig_cpu(enum cpu_led_event ledevt)
49{
50 struct led_trigger_cpu *trig = &__get_cpu_var(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}
72EXPORT_SYMBOL(ledtrig_cpu);
73
74static int ledtrig_cpu_syscore_suspend(void)
75{
76 ledtrig_cpu(CPU_LED_STOP);
77 return 0;
78}
79
80static void ledtrig_cpu_syscore_resume(void)
81{
82 ledtrig_cpu(CPU_LED_START);
83}
84
85static void ledtrig_cpu_syscore_shutdown(void)
86{
87 ledtrig_cpu(CPU_LED_HALTED);
88}
89
90static 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
96static 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
112static struct notifier_block ledtrig_cpu_nb = {
113 .notifier_call = ledtrig_cpu_notify,
114};
115
116static 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}
143module_init(ledtrig_cpu_init);
144
145static 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}
161module_exit(ledtrig_cpu_exit);
162
163MODULE_AUTHOR("Linus Walleij <linus.walleij@linaro.org>");
164MODULE_AUTHOR("Bryan Wu <bryan.wu@canonical.com>");
165MODULE_DESCRIPTION("CPU LED trigger");
166MODULE_LICENSE("GPL");