1 /*
2 * Generic implementation of a polled input device
3
4 * Copyright (c) 2007 Dmitry Torokhov
5 *
6 * This program is free software; you can redistribute it and/or modify it
7 * under the terms of the GNU General Public License version 2 as published by
8 * the Free Software Foundation.
9 */
10
11 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
12
13 #include <linux/jiffies.h>
14 #include <linux/slab.h>
15 #include <linux/mutex.h>
16 #include <linux/workqueue.h>
17 #include <linux/module.h>
18 #include <linux/input-polldev.h>
19
20 MODULE_AUTHOR("Dmitry Torokhov <dtor@mail.ru>");
21 MODULE_DESCRIPTION("Generic implementation of a polled input device");
22 MODULE_LICENSE("GPL v2");
23 MODULE_VERSION("0.1");
24
input_polldev_queue_work(struct input_polled_dev * dev)25 static void input_polldev_queue_work(struct input_polled_dev *dev)
26 {
27 unsigned long delay;
28
29 delay = msecs_to_jiffies(dev->poll_interval);
30 if (delay >= HZ)
31 delay = round_jiffies_relative(delay);
32
33 queue_delayed_work(system_freezable_wq, &dev->work, delay);
34 }
35
input_polled_device_work(struct work_struct * work)36 static void input_polled_device_work(struct work_struct *work)
37 {
38 struct input_polled_dev *dev =
39 container_of(work, struct input_polled_dev, work.work);
40
41 dev->poll(dev);
42 input_polldev_queue_work(dev);
43 }
44
input_open_polled_device(struct input_dev * input)45 static int input_open_polled_device(struct input_dev *input)
46 {
47 struct input_polled_dev *dev = input_get_drvdata(input);
48
49 if (dev->open)
50 dev->open(dev);
51
52 /* Only start polling if polling is enabled */
53 if (dev->poll_interval > 0) {
54 dev->poll(dev);
55 input_polldev_queue_work(dev);
56 }
57
58 return 0;
59 }
60
input_close_polled_device(struct input_dev * input)61 static void input_close_polled_device(struct input_dev *input)
62 {
63 struct input_polled_dev *dev = input_get_drvdata(input);
64
65 cancel_delayed_work_sync(&dev->work);
66
67 if (dev->close)
68 dev->close(dev);
69 }
70
71 /* SYSFS interface */
72
input_polldev_get_poll(struct device * dev,struct device_attribute * attr,char * buf)73 static ssize_t input_polldev_get_poll(struct device *dev,
74 struct device_attribute *attr, char *buf)
75 {
76 struct input_polled_dev *polldev = dev_get_drvdata(dev);
77
78 return sprintf(buf, "%d\n", polldev->poll_interval);
79 }
80
input_polldev_set_poll(struct device * dev,struct device_attribute * attr,const char * buf,size_t count)81 static ssize_t input_polldev_set_poll(struct device *dev,
82 struct device_attribute *attr, const char *buf,
83 size_t count)
84 {
85 struct input_polled_dev *polldev = dev_get_drvdata(dev);
86 struct input_dev *input = polldev->input;
87 unsigned int interval;
88 int err;
89
90 err = kstrtouint(buf, 0, &interval);
91 if (err)
92 return err;
93
94 if (interval < polldev->poll_interval_min)
95 return -EINVAL;
96
97 if (interval > polldev->poll_interval_max)
98 return -EINVAL;
99
100 mutex_lock(&input->mutex);
101
102 polldev->poll_interval = interval;
103
104 if (input->users) {
105 cancel_delayed_work_sync(&polldev->work);
106 if (polldev->poll_interval > 0)
107 input_polldev_queue_work(polldev);
108 }
109
110 mutex_unlock(&input->mutex);
111
112 return count;
113 }
114
115 static DEVICE_ATTR(poll, S_IRUGO | S_IWUSR, input_polldev_get_poll,
116 input_polldev_set_poll);
117
118
input_polldev_get_max(struct device * dev,struct device_attribute * attr,char * buf)119 static ssize_t input_polldev_get_max(struct device *dev,
120 struct device_attribute *attr, char *buf)
121 {
122 struct input_polled_dev *polldev = dev_get_drvdata(dev);
123
124 return sprintf(buf, "%d\n", polldev->poll_interval_max);
125 }
126
127 static DEVICE_ATTR(max, S_IRUGO, input_polldev_get_max, NULL);
128
input_polldev_get_min(struct device * dev,struct device_attribute * attr,char * buf)129 static ssize_t input_polldev_get_min(struct device *dev,
130 struct device_attribute *attr, char *buf)
131 {
132 struct input_polled_dev *polldev = dev_get_drvdata(dev);
133
134 return sprintf(buf, "%d\n", polldev->poll_interval_min);
135 }
136
137 static DEVICE_ATTR(min, S_IRUGO, input_polldev_get_min, NULL);
138
139 static struct attribute *sysfs_attrs[] = {
140 &dev_attr_poll.attr,
141 &dev_attr_max.attr,
142 &dev_attr_min.attr,
143 NULL
144 };
145
146 static struct attribute_group input_polldev_attribute_group = {
147 .attrs = sysfs_attrs
148 };
149
150 /**
151 * input_allocate_polled_device - allocate memory for polled device
152 *
153 * The function allocates memory for a polled device and also
154 * for an input device associated with this polled device.
155 */
input_allocate_polled_device(void)156 struct input_polled_dev *input_allocate_polled_device(void)
157 {
158 struct input_polled_dev *dev;
159
160 dev = kzalloc(sizeof(struct input_polled_dev), GFP_KERNEL);
161 if (!dev)
162 return NULL;
163
164 dev->input = input_allocate_device();
165 if (!dev->input) {
166 kfree(dev);
167 return NULL;
168 }
169
170 return dev;
171 }
172 EXPORT_SYMBOL(input_allocate_polled_device);
173
174 /**
175 * input_free_polled_device - free memory allocated for polled device
176 * @dev: device to free
177 *
178 * The function frees memory allocated for polling device and drops
179 * reference to the associated input device.
180 */
input_free_polled_device(struct input_polled_dev * dev)181 void input_free_polled_device(struct input_polled_dev *dev)
182 {
183 if (dev) {
184 input_free_device(dev->input);
185 kfree(dev);
186 }
187 }
188 EXPORT_SYMBOL(input_free_polled_device);
189
190 /**
191 * input_register_polled_device - register polled device
192 * @dev: device to register
193 *
194 * The function registers previously initialized polled input device
195 * with input layer. The device should be allocated with call to
196 * input_allocate_polled_device(). Callers should also set up poll()
197 * method and set up capabilities (id, name, phys, bits) of the
198 * corresponding input_dev structure.
199 */
input_register_polled_device(struct input_polled_dev * dev)200 int input_register_polled_device(struct input_polled_dev *dev)
201 {
202 struct input_dev *input = dev->input;
203 int error;
204
205 input_set_drvdata(input, dev);
206 INIT_DELAYED_WORK(&dev->work, input_polled_device_work);
207 if (!dev->poll_interval)
208 dev->poll_interval = 500;
209 if (!dev->poll_interval_max)
210 dev->poll_interval_max = dev->poll_interval;
211 input->open = input_open_polled_device;
212 input->close = input_close_polled_device;
213
214 error = input_register_device(input);
215 if (error)
216 return error;
217
218 error = sysfs_create_group(&input->dev.kobj,
219 &input_polldev_attribute_group);
220 if (error) {
221 input_unregister_device(input);
222 return error;
223 }
224
225 /*
226 * Take extra reference to the underlying input device so
227 * that it survives call to input_unregister_polled_device()
228 * and is deleted only after input_free_polled_device()
229 * has been invoked. This is needed to ease task of freeing
230 * sparse keymaps.
231 */
232 input_get_device(input);
233
234 return 0;
235 }
236 EXPORT_SYMBOL(input_register_polled_device);
237
238 /**
239 * input_unregister_polled_device - unregister polled device
240 * @dev: device to unregister
241 *
242 * The function unregisters previously registered polled input
243 * device from input layer. Polling is stopped and device is
244 * ready to be freed with call to input_free_polled_device().
245 */
input_unregister_polled_device(struct input_polled_dev * dev)246 void input_unregister_polled_device(struct input_polled_dev *dev)
247 {
248 sysfs_remove_group(&dev->input->dev.kobj,
249 &input_polldev_attribute_group);
250
251 input_unregister_device(dev->input);
252 }
253 EXPORT_SYMBOL(input_unregister_polled_device);
254