1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * LED Heartbeat Trigger
4 *
5 * Copyright (C) 2006 Atsushi Nemoto <anemo@mba.ocn.ne.jp>
6 *
7 * Based on Richard Purdie's ledtrig-timer.c and some arch's
8 * CONFIG_HEARTBEAT code.
9 */
10
11#include <linux/module.h>
12#include <linux/kernel.h>
13#include <linux/init.h>
14#include <linux/panic_notifier.h>
15#include <linux/slab.h>
16#include <linux/timer.h>
17#include <linux/sched.h>
18#include <linux/sched/loadavg.h>
19#include <linux/leds.h>
20#include <linux/reboot.h>
21#include "../leds.h"
22
23static int panic_heartbeats;
24
25struct heartbeat_trig_data {
26	struct led_classdev *led_cdev;
27	unsigned int phase;
28	unsigned int period;
29	struct timer_list timer;
30	unsigned int invert;
31};
32
33static void led_heartbeat_function(struct timer_list *t)
34{
35	struct heartbeat_trig_data *heartbeat_data =
36		from_timer(heartbeat_data, t, timer);
37	struct led_classdev *led_cdev;
38	unsigned long brightness = LED_OFF;
39	unsigned long delay = 0;
40
41	led_cdev = heartbeat_data->led_cdev;
42
43	if (unlikely(panic_heartbeats)) {
44		led_set_brightness_nosleep(led_cdev, LED_OFF);
45		return;
46	}
47
48	if (test_and_clear_bit(LED_BLINK_BRIGHTNESS_CHANGE, &led_cdev->work_flags))
49		led_cdev->blink_brightness = led_cdev->new_blink_brightness;
50
51	/* acts like an actual heart beat -- ie thump-thump-pause... */
52	switch (heartbeat_data->phase) {
53	case 0:
54		/*
55		 * The hyperbolic function below modifies the
56		 * heartbeat period length in dependency of the
57		 * current (1min) load. It goes through the points
58		 * f(0)=1260, f(1)=860, f(5)=510, f(inf)->300.
59		 */
60		heartbeat_data->period = 300 +
61			(6720 << FSHIFT) / (5 * avenrun[0] + (7 << FSHIFT));
62		heartbeat_data->period =
63			msecs_to_jiffies(heartbeat_data->period);
64		delay = msecs_to_jiffies(70);
65		heartbeat_data->phase++;
66		if (!heartbeat_data->invert)
67			brightness = led_cdev->blink_brightness;
68		break;
69	case 1:
70		delay = heartbeat_data->period / 4 - msecs_to_jiffies(70);
71		heartbeat_data->phase++;
72		if (heartbeat_data->invert)
73			brightness = led_cdev->blink_brightness;
74		break;
75	case 2:
76		delay = msecs_to_jiffies(70);
77		heartbeat_data->phase++;
78		if (!heartbeat_data->invert)
79			brightness = led_cdev->blink_brightness;
80		break;
81	default:
82		delay = heartbeat_data->period - heartbeat_data->period / 4 -
83			msecs_to_jiffies(70);
84		heartbeat_data->phase = 0;
85		if (heartbeat_data->invert)
86			brightness = led_cdev->blink_brightness;
87		break;
88	}
89
90	led_set_brightness_nosleep(led_cdev, brightness);
91	mod_timer(&heartbeat_data->timer, jiffies + delay);
92}
93
94static ssize_t led_invert_show(struct device *dev,
95		struct device_attribute *attr, char *buf)
96{
97	struct heartbeat_trig_data *heartbeat_data =
98		led_trigger_get_drvdata(dev);
99
100	return sprintf(buf, "%u\n", heartbeat_data->invert);
101}
102
103static ssize_t led_invert_store(struct device *dev,
104		struct device_attribute *attr, const char *buf, size_t size)
105{
106	struct heartbeat_trig_data *heartbeat_data =
107		led_trigger_get_drvdata(dev);
108	unsigned long state;
109	int ret;
110
111	ret = kstrtoul(buf, 0, &state);
112	if (ret)
113		return ret;
114
115	heartbeat_data->invert = !!state;
116
117	return size;
118}
119
120static DEVICE_ATTR(invert, 0644, led_invert_show, led_invert_store);
121
122static struct attribute *heartbeat_trig_attrs[] = {
123	&dev_attr_invert.attr,
124	NULL
125};
126ATTRIBUTE_GROUPS(heartbeat_trig);
127
128static int heartbeat_trig_activate(struct led_classdev *led_cdev)
129{
130	struct heartbeat_trig_data *heartbeat_data;
131
132	heartbeat_data = kzalloc(sizeof(*heartbeat_data), GFP_KERNEL);
133	if (!heartbeat_data)
134		return -ENOMEM;
135
136	led_set_trigger_data(led_cdev, heartbeat_data);
137	heartbeat_data->led_cdev = led_cdev;
138
139	timer_setup(&heartbeat_data->timer, led_heartbeat_function, 0);
140	heartbeat_data->phase = 0;
141	if (!led_cdev->blink_brightness)
142		led_cdev->blink_brightness = led_cdev->max_brightness;
143	led_heartbeat_function(&heartbeat_data->timer);
144	set_bit(LED_BLINK_SW, &led_cdev->work_flags);
145
146	return 0;
147}
148
149static void heartbeat_trig_deactivate(struct led_classdev *led_cdev)
150{
151	struct heartbeat_trig_data *heartbeat_data =
152		led_get_trigger_data(led_cdev);
153
154	timer_shutdown_sync(&heartbeat_data->timer);
155	kfree(heartbeat_data);
156	clear_bit(LED_BLINK_SW, &led_cdev->work_flags);
157}
158
159static struct led_trigger heartbeat_led_trigger = {
160	.name     = "heartbeat",
161	.activate = heartbeat_trig_activate,
162	.deactivate = heartbeat_trig_deactivate,
163	.groups = heartbeat_trig_groups,
164};
165
166static int heartbeat_reboot_notifier(struct notifier_block *nb,
167				     unsigned long code, void *unused)
168{
169	led_trigger_unregister(&heartbeat_led_trigger);
170	return NOTIFY_DONE;
171}
172
173static int heartbeat_panic_notifier(struct notifier_block *nb,
174				     unsigned long code, void *unused)
175{
176	panic_heartbeats = 1;
177	return NOTIFY_DONE;
178}
179
180static struct notifier_block heartbeat_reboot_nb = {
181	.notifier_call = heartbeat_reboot_notifier,
182};
183
184static struct notifier_block heartbeat_panic_nb = {
185	.notifier_call = heartbeat_panic_notifier,
186};
187
188static int __init heartbeat_trig_init(void)
189{
190	int rc = led_trigger_register(&heartbeat_led_trigger);
191
192	if (!rc) {
193		atomic_notifier_chain_register(&panic_notifier_list,
194					       &heartbeat_panic_nb);
195		register_reboot_notifier(&heartbeat_reboot_nb);
196	}
197	return rc;
198}
199
200static void __exit heartbeat_trig_exit(void)
201{
202	unregister_reboot_notifier(&heartbeat_reboot_nb);
203	atomic_notifier_chain_unregister(&panic_notifier_list,
204					 &heartbeat_panic_nb);
205	led_trigger_unregister(&heartbeat_led_trigger);
206}
207
208module_init(heartbeat_trig_init);
209module_exit(heartbeat_trig_exit);
210
211MODULE_AUTHOR("Atsushi Nemoto <anemo@mba.ocn.ne.jp>");
212MODULE_DESCRIPTION("Heartbeat LED trigger");
213MODULE_LICENSE("GPL v2");
214