Root/drivers/leds/ledtrig-transient.c

1/*
2 * LED Kernel Transient Trigger
3 *
4 * Copyright (C) 2012 Shuah Khan <shuahkhan@gmail.com>
5 *
6 * Based on Richard Purdie's ledtrig-timer.c and Atsushi Nemoto's
7 * ledtrig-heartbeat.c
8 * Design and use-case input from Jonas Bonn <jonas@southpole.se> and
9 * Neil Brown <neilb@suse.de>
10 *
11 * This program is free software; you can redistribute it and/or modify
12 * it under the terms of the GNU General Public License version 2 as
13 * published by the Free Software Foundation.
14 *
15 */
16/*
17 * Transient trigger allows one shot timer activation. Please refer to
18 * Documentation/leds/ledtrig-transient.txt for details
19*/
20
21#include <linux/module.h>
22#include <linux/kernel.h>
23#include <linux/init.h>
24#include <linux/device.h>
25#include <linux/slab.h>
26#include <linux/timer.h>
27#include <linux/leds.h>
28#include "leds.h"
29
30struct transient_trig_data {
31    int activate;
32    int state;
33    int restore_state;
34    unsigned long duration;
35    struct timer_list timer;
36};
37
38static void transient_timer_function(unsigned long data)
39{
40    struct led_classdev *led_cdev = (struct led_classdev *) data;
41    struct transient_trig_data *transient_data = led_cdev->trigger_data;
42
43    transient_data->activate = 0;
44    __led_set_brightness(led_cdev, transient_data->restore_state);
45}
46
47static ssize_t transient_activate_show(struct device *dev,
48        struct device_attribute *attr, char *buf)
49{
50    struct led_classdev *led_cdev = dev_get_drvdata(dev);
51    struct transient_trig_data *transient_data = led_cdev->trigger_data;
52
53    return sprintf(buf, "%d\n", transient_data->activate);
54}
55
56static ssize_t transient_activate_store(struct device *dev,
57        struct device_attribute *attr, const char *buf, size_t size)
58{
59    struct led_classdev *led_cdev = dev_get_drvdata(dev);
60    struct transient_trig_data *transient_data = led_cdev->trigger_data;
61    unsigned long state;
62    ssize_t ret;
63
64    ret = kstrtoul(buf, 10, &state);
65    if (ret)
66        return ret;
67
68    if (state != 1 && state != 0)
69        return -EINVAL;
70
71    /* cancel the running timer */
72    if (state == 0 && transient_data->activate == 1) {
73        del_timer(&transient_data->timer);
74        transient_data->activate = state;
75        __led_set_brightness(led_cdev, transient_data->restore_state);
76        return size;
77    }
78
79    /* start timer if there is no active timer */
80    if (state == 1 && transient_data->activate == 0 &&
81        transient_data->duration != 0) {
82        transient_data->activate = state;
83        __led_set_brightness(led_cdev, transient_data->state);
84        transient_data->restore_state =
85            (transient_data->state == LED_FULL) ? LED_OFF : LED_FULL;
86        mod_timer(&transient_data->timer,
87              jiffies + transient_data->duration);
88    }
89
90    /* state == 0 && transient_data->activate == 0
91        timer is not active - just return */
92    /* state == 1 && transient_data->activate == 1
93        timer is already active - just return */
94
95    return size;
96}
97
98static ssize_t transient_duration_show(struct device *dev,
99        struct device_attribute *attr, char *buf)
100{
101    struct led_classdev *led_cdev = dev_get_drvdata(dev);
102    struct transient_trig_data *transient_data = led_cdev->trigger_data;
103
104    return sprintf(buf, "%lu\n", transient_data->duration);
105}
106
107static ssize_t transient_duration_store(struct device *dev,
108        struct device_attribute *attr, const char *buf, size_t size)
109{
110    struct led_classdev *led_cdev = dev_get_drvdata(dev);
111    struct transient_trig_data *transient_data = led_cdev->trigger_data;
112    unsigned long state;
113    ssize_t ret;
114
115    ret = kstrtoul(buf, 10, &state);
116    if (ret)
117        return ret;
118
119    transient_data->duration = state;
120    return size;
121}
122
123static ssize_t transient_state_show(struct device *dev,
124        struct device_attribute *attr, char *buf)
125{
126    struct led_classdev *led_cdev = dev_get_drvdata(dev);
127    struct transient_trig_data *transient_data = led_cdev->trigger_data;
128    int state;
129
130    state = (transient_data->state == LED_FULL) ? 1 : 0;
131    return sprintf(buf, "%d\n", state);
132}
133
134static ssize_t transient_state_store(struct device *dev,
135        struct device_attribute *attr, const char *buf, size_t size)
136{
137    struct led_classdev *led_cdev = dev_get_drvdata(dev);
138    struct transient_trig_data *transient_data = led_cdev->trigger_data;
139    unsigned long state;
140    ssize_t ret;
141
142    ret = kstrtoul(buf, 10, &state);
143    if (ret)
144        return ret;
145
146    if (state != 1 && state != 0)
147        return -EINVAL;
148
149    transient_data->state = (state == 1) ? LED_FULL : LED_OFF;
150    return size;
151}
152
153static DEVICE_ATTR(activate, 0644, transient_activate_show,
154           transient_activate_store);
155static DEVICE_ATTR(duration, 0644, transient_duration_show,
156           transient_duration_store);
157static DEVICE_ATTR(state, 0644, transient_state_show, transient_state_store);
158
159static void transient_trig_activate(struct led_classdev *led_cdev)
160{
161    int rc;
162    struct transient_trig_data *tdata;
163
164    tdata = kzalloc(sizeof(struct transient_trig_data), GFP_KERNEL);
165    if (!tdata) {
166        dev_err(led_cdev->dev,
167            "unable to allocate transient trigger\n");
168        return;
169    }
170    led_cdev->trigger_data = tdata;
171
172    rc = device_create_file(led_cdev->dev, &dev_attr_activate);
173    if (rc)
174        goto err_out;
175
176    rc = device_create_file(led_cdev->dev, &dev_attr_duration);
177    if (rc)
178        goto err_out_duration;
179
180    rc = device_create_file(led_cdev->dev, &dev_attr_state);
181    if (rc)
182        goto err_out_state;
183
184    setup_timer(&tdata->timer, transient_timer_function,
185            (unsigned long) led_cdev);
186    led_cdev->activated = true;
187
188    return;
189
190err_out_state:
191    device_remove_file(led_cdev->dev, &dev_attr_duration);
192err_out_duration:
193    device_remove_file(led_cdev->dev, &dev_attr_activate);
194err_out:
195    dev_err(led_cdev->dev, "unable to register transient trigger\n");
196    led_cdev->trigger_data = NULL;
197    kfree(tdata);
198}
199
200static void transient_trig_deactivate(struct led_classdev *led_cdev)
201{
202    struct transient_trig_data *transient_data = led_cdev->trigger_data;
203
204    if (led_cdev->activated) {
205        del_timer_sync(&transient_data->timer);
206        __led_set_brightness(led_cdev, transient_data->restore_state);
207        device_remove_file(led_cdev->dev, &dev_attr_activate);
208        device_remove_file(led_cdev->dev, &dev_attr_duration);
209        device_remove_file(led_cdev->dev, &dev_attr_state);
210        led_cdev->trigger_data = NULL;
211        led_cdev->activated = false;
212        kfree(transient_data);
213    }
214}
215
216static struct led_trigger transient_trigger = {
217    .name = "transient",
218    .activate = transient_trig_activate,
219    .deactivate = transient_trig_deactivate,
220};
221
222static int __init transient_trig_init(void)
223{
224    return led_trigger_register(&transient_trigger);
225}
226
227static void __exit transient_trig_exit(void)
228{
229    led_trigger_unregister(&transient_trigger);
230}
231
232module_init(transient_trig_init);
233module_exit(transient_trig_exit);
234
235MODULE_AUTHOR("Shuah Khan <shuahkhan@gmail.com>");
236MODULE_DESCRIPTION("Transient LED trigger");
237MODULE_LICENSE("GPL");
238

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