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 
23 static int panic_heartbeats;
24 
25 struct 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 
33 static 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 
94 static 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 
103 static 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 
120 static DEVICE_ATTR(invert, 0644, led_invert_show, led_invert_store);
121 
122 static struct attribute *heartbeat_trig_attrs[] = {
123 	&dev_attr_invert.attr,
124 	NULL
125 };
126 ATTRIBUTE_GROUPS(heartbeat_trig);
127 
128 static 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 
149 static 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 
159 static 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 
166 static 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 
173 static 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 
180 static struct notifier_block heartbeat_reboot_nb = {
181 	.notifier_call = heartbeat_reboot_notifier,
182 };
183 
184 static struct notifier_block heartbeat_panic_nb = {
185 	.notifier_call = heartbeat_panic_notifier,
186 };
187 
188 static 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 
200 static 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 
208 module_init(heartbeat_trig_init);
209 module_exit(heartbeat_trig_exit);
210 
211 MODULE_AUTHOR("Atsushi Nemoto <anemo@mba.ocn.ne.jp>");
212 MODULE_DESCRIPTION("Heartbeat LED trigger");
213 MODULE_LICENSE("GPL v2");
214