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/slab.h>
15#include <linux/timer.h>
16#include <linux/sched.h>
17#include <linux/sched/loadavg.h>
18#include <linux/leds.h>
19#include <linux/reboot.h>
20#include "../leds.h"
21
22static int panic_heartbeats;
23
24struct heartbeat_trig_data {
25	struct led_classdev *led_cdev;
26	unsigned int phase;
27	unsigned int period;
28	struct timer_list timer;
29	unsigned int invert;
30};
31
32static void led_heartbeat_function(struct timer_list *t)
33{
34	struct heartbeat_trig_data *heartbeat_data =
35		from_timer(heartbeat_data, t, timer);
36	struct led_classdev *led_cdev;
37	unsigned long brightness = LED_OFF;
38	unsigned long delay = 0;
39
40	led_cdev = heartbeat_data->led_cdev;
41
42	if (unlikely(panic_heartbeats)) {
43		led_set_brightness_nosleep(led_cdev, LED_OFF);
44		return;
45	}
46
47	if (test_and_clear_bit(LED_BLINK_BRIGHTNESS_CHANGE, &led_cdev->work_flags))
48		led_cdev->blink_brightness = led_cdev->new_blink_brightness;
49
50	/* acts like an actual heart beat -- ie thump-thump-pause... */
51	switch (heartbeat_data->phase) {
52	case 0:
53		/*
54		 * The hyperbolic function below modifies the
55		 * heartbeat period length in dependency of the
56		 * current (1min) load. It goes through the points
57		 * f(0)=1260, f(1)=860, f(5)=510, f(inf)->300.
58		 */
59		heartbeat_data->period = 300 +
60			(6720 << FSHIFT) / (5 * avenrun[0] + (7 << FSHIFT));
61		heartbeat_data->period =
62			msecs_to_jiffies(heartbeat_data->period);
63		delay = msecs_to_jiffies(70);
64		heartbeat_data->phase++;
65		if (!heartbeat_data->invert)
66			brightness = led_cdev->blink_brightness;
67		break;
68	case 1:
69		delay = heartbeat_data->period / 4 - msecs_to_jiffies(70);
70		heartbeat_data->phase++;
71		if (heartbeat_data->invert)
72			brightness = led_cdev->blink_brightness;
73		break;
74	case 2:
75		delay = msecs_to_jiffies(70);
76		heartbeat_data->phase++;
77		if (!heartbeat_data->invert)
78			brightness = led_cdev->blink_brightness;
79		break;
80	default:
81		delay = heartbeat_data->period - heartbeat_data->period / 4 -
82			msecs_to_jiffies(70);
83		heartbeat_data->phase = 0;
84		if (heartbeat_data->invert)
85			brightness = led_cdev->blink_brightness;
86		break;
87	}
88
89	led_set_brightness_nosleep(led_cdev, brightness);
90	mod_timer(&heartbeat_data->timer, jiffies + delay);
91}
92
93static ssize_t led_invert_show(struct device *dev,
94		struct device_attribute *attr, char *buf)
95{
96	struct heartbeat_trig_data *heartbeat_data =
97		led_trigger_get_drvdata(dev);
98
99	return sprintf(buf, "%u\n", heartbeat_data->invert);
100}
101
102static ssize_t led_invert_store(struct device *dev,
103		struct device_attribute *attr, const char *buf, size_t size)
104{
105	struct heartbeat_trig_data *heartbeat_data =
106		led_trigger_get_drvdata(dev);
107	unsigned long state;
108	int ret;
109
110	ret = kstrtoul(buf, 0, &state);
111	if (ret)
112		return ret;
113
114	heartbeat_data->invert = !!state;
115
116	return size;
117}
118
119static DEVICE_ATTR(invert, 0644, led_invert_show, led_invert_store);
120
121static struct attribute *heartbeat_trig_attrs[] = {
122	&dev_attr_invert.attr,
123	NULL
124};
125ATTRIBUTE_GROUPS(heartbeat_trig);
126
127static int heartbeat_trig_activate(struct led_classdev *led_cdev)
128{
129	struct heartbeat_trig_data *heartbeat_data;
130
131	heartbeat_data = kzalloc(sizeof(*heartbeat_data), GFP_KERNEL);
132	if (!heartbeat_data)
133		return -ENOMEM;
134
135	led_set_trigger_data(led_cdev, heartbeat_data);
136	heartbeat_data->led_cdev = led_cdev;
137
138	timer_setup(&heartbeat_data->timer, led_heartbeat_function, 0);
139	heartbeat_data->phase = 0;
140	if (!led_cdev->blink_brightness)
141		led_cdev->blink_brightness = led_cdev->max_brightness;
142	led_heartbeat_function(&heartbeat_data->timer);
143	set_bit(LED_BLINK_SW, &led_cdev->work_flags);
144
145	return 0;
146}
147
148static void heartbeat_trig_deactivate(struct led_classdev *led_cdev)
149{
150	struct heartbeat_trig_data *heartbeat_data =
151		led_get_trigger_data(led_cdev);
152
153	del_timer_sync(&heartbeat_data->timer);
154	kfree(heartbeat_data);
155	clear_bit(LED_BLINK_SW, &led_cdev->work_flags);
156}
157
158static struct led_trigger heartbeat_led_trigger = {
159	.name     = "heartbeat",
160	.activate = heartbeat_trig_activate,
161	.deactivate = heartbeat_trig_deactivate,
162	.groups = heartbeat_trig_groups,
163};
164
165static int heartbeat_reboot_notifier(struct notifier_block *nb,
166				     unsigned long code, void *unused)
167{
168	led_trigger_unregister(&heartbeat_led_trigger);
169	return NOTIFY_DONE;
170}
171
172static int heartbeat_panic_notifier(struct notifier_block *nb,
173				     unsigned long code, void *unused)
174{
175	panic_heartbeats = 1;
176	return NOTIFY_DONE;
177}
178
179static struct notifier_block heartbeat_reboot_nb = {
180	.notifier_call = heartbeat_reboot_notifier,
181};
182
183static struct notifier_block heartbeat_panic_nb = {
184	.notifier_call = heartbeat_panic_notifier,
185};
186
187static int __init heartbeat_trig_init(void)
188{
189	int rc = led_trigger_register(&heartbeat_led_trigger);
190
191	if (!rc) {
192		atomic_notifier_chain_register(&panic_notifier_list,
193					       &heartbeat_panic_nb);
194		register_reboot_notifier(&heartbeat_reboot_nb);
195	}
196	return rc;
197}
198
199static void __exit heartbeat_trig_exit(void)
200{
201	unregister_reboot_notifier(&heartbeat_reboot_nb);
202	atomic_notifier_chain_unregister(&panic_notifier_list,
203					 &heartbeat_panic_nb);
204	led_trigger_unregister(&heartbeat_led_trigger);
205}
206
207module_init(heartbeat_trig_init);
208module_exit(heartbeat_trig_exit);
209
210MODULE_AUTHOR("Atsushi Nemoto <anemo@mba.ocn.ne.jp>");
211MODULE_DESCRIPTION("Heartbeat LED trigger");
212MODULE_LICENSE("GPL v2");
213