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 
22 static int panic_heartbeats;
23 
24 struct 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 
32 static 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 
93 static 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 
102 static 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 
119 static DEVICE_ATTR(invert, 0644, led_invert_show, led_invert_store);
120 
121 static struct attribute *heartbeat_trig_attrs[] = {
122 	&dev_attr_invert.attr,
123 	NULL
124 };
125 ATTRIBUTE_GROUPS(heartbeat_trig);
126 
127 static 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 
148 static 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 
158 static 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 
165 static 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 
172 static 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 
179 static struct notifier_block heartbeat_reboot_nb = {
180 	.notifier_call = heartbeat_reboot_notifier,
181 };
182 
183 static struct notifier_block heartbeat_panic_nb = {
184 	.notifier_call = heartbeat_panic_notifier,
185 };
186 
187 static 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 
199 static 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 
207 module_init(heartbeat_trig_init);
208 module_exit(heartbeat_trig_exit);
209 
210 MODULE_AUTHOR("Atsushi Nemoto <anemo@mba.ocn.ne.jp>");
211 MODULE_DESCRIPTION("Heartbeat LED trigger");
212 MODULE_LICENSE("GPL v2");
213