1 // SPDX-License-Identifier: GPL-2.0
2 //
3 // LED Kernel Transient Trigger
4 //
5 // Transient trigger allows one shot timer activation. Please refer to
6 // Documentation/leds/ledtrig-transient.rst for details
7 // Copyright (C) 2012 Shuah Khan <shuahkhan@gmail.com>
8 //
9 // Based on Richard Purdie's ledtrig-timer.c and Atsushi Nemoto's
10 // ledtrig-heartbeat.c
11 // Design and use-case input from Jonas Bonn <jonas@southpole.se> and
12 // Neil Brown <neilb@suse.de>
13 
14 #include <linux/module.h>
15 #include <linux/kernel.h>
16 #include <linux/init.h>
17 #include <linux/device.h>
18 #include <linux/slab.h>
19 #include <linux/timer.h>
20 #include <linux/leds.h>
21 #include "../leds.h"
22 
23 struct transient_trig_data {
24 	int activate;
25 	int state;
26 	int restore_state;
27 	unsigned long duration;
28 	struct timer_list timer;
29 	struct led_classdev *led_cdev;
30 };
31 
32 static void transient_timer_function(struct timer_list *t)
33 {
34 	struct transient_trig_data *transient_data =
35 		from_timer(transient_data, t, timer);
36 	struct led_classdev *led_cdev = transient_data->led_cdev;
37 
38 	transient_data->activate = 0;
39 	led_set_brightness_nosleep(led_cdev, transient_data->restore_state);
40 }
41 
42 static ssize_t transient_activate_show(struct device *dev,
43 		struct device_attribute *attr, char *buf)
44 {
45 	struct transient_trig_data *transient_data =
46 		led_trigger_get_drvdata(dev);
47 
48 	return sprintf(buf, "%d\n", transient_data->activate);
49 }
50 
51 static ssize_t transient_activate_store(struct device *dev,
52 		struct device_attribute *attr, const char *buf, size_t size)
53 {
54 	struct led_classdev *led_cdev = led_trigger_get_led(dev);
55 	struct transient_trig_data *transient_data =
56 		led_trigger_get_drvdata(dev);
57 	unsigned long state;
58 	ssize_t ret;
59 
60 	ret = kstrtoul(buf, 10, &state);
61 	if (ret)
62 		return ret;
63 
64 	if (state != 1 && state != 0)
65 		return -EINVAL;
66 
67 	/* cancel the running timer */
68 	if (state == 0 && transient_data->activate == 1) {
69 		del_timer(&transient_data->timer);
70 		transient_data->activate = state;
71 		led_set_brightness_nosleep(led_cdev,
72 					transient_data->restore_state);
73 		return size;
74 	}
75 
76 	/* start timer if there is no active timer */
77 	if (state == 1 && transient_data->activate == 0 &&
78 	    transient_data->duration != 0) {
79 		transient_data->activate = state;
80 		led_set_brightness_nosleep(led_cdev, transient_data->state);
81 		transient_data->restore_state =
82 		    (transient_data->state == LED_FULL) ? LED_OFF : LED_FULL;
83 		mod_timer(&transient_data->timer,
84 			  jiffies + msecs_to_jiffies(transient_data->duration));
85 	}
86 
87 	/* state == 0 && transient_data->activate == 0
88 		timer is not active - just return */
89 	/* state == 1 && transient_data->activate == 1
90 		timer is already active - just return */
91 
92 	return size;
93 }
94 
95 static ssize_t transient_duration_show(struct device *dev,
96 		struct device_attribute *attr, char *buf)
97 {
98 	struct transient_trig_data *transient_data = led_trigger_get_drvdata(dev);
99 
100 	return sprintf(buf, "%lu\n", transient_data->duration);
101 }
102 
103 static ssize_t transient_duration_store(struct device *dev,
104 		struct device_attribute *attr, const char *buf, size_t size)
105 {
106 	struct transient_trig_data *transient_data =
107 		led_trigger_get_drvdata(dev);
108 	unsigned long state;
109 	ssize_t ret;
110 
111 	ret = kstrtoul(buf, 10, &state);
112 	if (ret)
113 		return ret;
114 
115 	transient_data->duration = state;
116 	return size;
117 }
118 
119 static ssize_t transient_state_show(struct device *dev,
120 		struct device_attribute *attr, char *buf)
121 {
122 	struct transient_trig_data *transient_data =
123 		led_trigger_get_drvdata(dev);
124 	int state;
125 
126 	state = (transient_data->state == LED_FULL) ? 1 : 0;
127 	return sprintf(buf, "%d\n", state);
128 }
129 
130 static ssize_t transient_state_store(struct device *dev,
131 		struct device_attribute *attr, const char *buf, size_t size)
132 {
133 	struct transient_trig_data *transient_data =
134 		led_trigger_get_drvdata(dev);
135 	unsigned long state;
136 	ssize_t ret;
137 
138 	ret = kstrtoul(buf, 10, &state);
139 	if (ret)
140 		return ret;
141 
142 	if (state != 1 && state != 0)
143 		return -EINVAL;
144 
145 	transient_data->state = (state == 1) ? LED_FULL : LED_OFF;
146 	return size;
147 }
148 
149 static DEVICE_ATTR(activate, 0644, transient_activate_show,
150 		   transient_activate_store);
151 static DEVICE_ATTR(duration, 0644, transient_duration_show,
152 		   transient_duration_store);
153 static DEVICE_ATTR(state, 0644, transient_state_show, transient_state_store);
154 
155 static struct attribute *transient_trig_attrs[] = {
156 	&dev_attr_activate.attr,
157 	&dev_attr_duration.attr,
158 	&dev_attr_state.attr,
159 	NULL
160 };
161 ATTRIBUTE_GROUPS(transient_trig);
162 
163 static int transient_trig_activate(struct led_classdev *led_cdev)
164 {
165 	struct transient_trig_data *tdata;
166 
167 	tdata = kzalloc(sizeof(struct transient_trig_data), GFP_KERNEL);
168 	if (!tdata)
169 		return -ENOMEM;
170 
171 	led_set_trigger_data(led_cdev, tdata);
172 	tdata->led_cdev = led_cdev;
173 
174 	timer_setup(&tdata->timer, transient_timer_function, 0);
175 
176 	return 0;
177 }
178 
179 static void transient_trig_deactivate(struct led_classdev *led_cdev)
180 {
181 	struct transient_trig_data *transient_data = led_get_trigger_data(led_cdev);
182 
183 	timer_shutdown_sync(&transient_data->timer);
184 	led_set_brightness_nosleep(led_cdev, transient_data->restore_state);
185 	kfree(transient_data);
186 }
187 
188 static struct led_trigger transient_trigger = {
189 	.name     = "transient",
190 	.activate = transient_trig_activate,
191 	.deactivate = transient_trig_deactivate,
192 	.groups = transient_trig_groups,
193 };
194 module_led_trigger(transient_trigger);
195 
196 MODULE_AUTHOR("Shuah Khan <shuahkhan@gmail.com>");
197 MODULE_DESCRIPTION("Transient LED trigger");
198 MODULE_LICENSE("GPL v2");
199