1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Support for polling mode for input devices.
4  */
5 
6 #include <linux/device.h>
7 #include <linux/input.h>
8 #include <linux/jiffies.h>
9 #include <linux/mutex.h>
10 #include <linux/slab.h>
11 #include <linux/types.h>
12 #include <linux/workqueue.h>
13 #include "input-poller.h"
14 
15 struct input_dev_poller {
16 	void (*poll)(struct input_dev *dev);
17 
18 	unsigned int poll_interval; /* msec */
19 	unsigned int poll_interval_max; /* msec */
20 	unsigned int poll_interval_min; /* msec */
21 
22 	struct input_dev *input;
23 	struct delayed_work work;
24 };
25 
input_dev_poller_queue_work(struct input_dev_poller * poller)26 static void input_dev_poller_queue_work(struct input_dev_poller *poller)
27 {
28 	unsigned long delay;
29 
30 	delay = msecs_to_jiffies(poller->poll_interval);
31 	if (delay >= HZ)
32 		delay = round_jiffies_relative(delay);
33 
34 	queue_delayed_work(system_freezable_wq, &poller->work, delay);
35 }
36 
input_dev_poller_work(struct work_struct * work)37 static void input_dev_poller_work(struct work_struct *work)
38 {
39 	struct input_dev_poller *poller =
40 		container_of(work, struct input_dev_poller, work.work);
41 
42 	poller->poll(poller->input);
43 	input_dev_poller_queue_work(poller);
44 }
45 
input_dev_poller_finalize(struct input_dev_poller * poller)46 void input_dev_poller_finalize(struct input_dev_poller *poller)
47 {
48 	if (!poller->poll_interval)
49 		poller->poll_interval = 500;
50 	if (!poller->poll_interval_max)
51 		poller->poll_interval_max = poller->poll_interval;
52 }
53 
input_dev_poller_start(struct input_dev_poller * poller)54 void input_dev_poller_start(struct input_dev_poller *poller)
55 {
56 	/* Only start polling if polling is enabled */
57 	if (poller->poll_interval > 0) {
58 		poller->poll(poller->input);
59 		input_dev_poller_queue_work(poller);
60 	}
61 }
62 
input_dev_poller_stop(struct input_dev_poller * poller)63 void input_dev_poller_stop(struct input_dev_poller *poller)
64 {
65 	cancel_delayed_work_sync(&poller->work);
66 }
67 
input_setup_polling(struct input_dev * dev,void (* poll_fn)(struct input_dev * dev))68 int input_setup_polling(struct input_dev *dev,
69 			void (*poll_fn)(struct input_dev *dev))
70 {
71 	struct input_dev_poller *poller;
72 
73 	poller = kzalloc(sizeof(*poller), GFP_KERNEL);
74 	if (!poller) {
75 		/*
76 		 * We want to show message even though kzalloc() may have
77 		 * printed backtrace as knowing what instance of input
78 		 * device we were dealing with is helpful.
79 		 */
80 		dev_err(dev->dev.parent ?: &dev->dev,
81 			"%s: unable to allocate poller structure\n", __func__);
82 		return -ENOMEM;
83 	}
84 
85 	INIT_DELAYED_WORK(&poller->work, input_dev_poller_work);
86 	poller->input = dev;
87 	poller->poll = poll_fn;
88 
89 	dev->poller = poller;
90 	return 0;
91 }
92 EXPORT_SYMBOL(input_setup_polling);
93 
input_dev_ensure_poller(struct input_dev * dev)94 static bool input_dev_ensure_poller(struct input_dev *dev)
95 {
96 	if (!dev->poller) {
97 		dev_err(dev->dev.parent ?: &dev->dev,
98 			"poller structure has not been set up\n");
99 		return false;
100 	}
101 
102 	return true;
103 }
104 
input_set_poll_interval(struct input_dev * dev,unsigned int interval)105 void input_set_poll_interval(struct input_dev *dev, unsigned int interval)
106 {
107 	if (input_dev_ensure_poller(dev))
108 		dev->poller->poll_interval = interval;
109 }
110 EXPORT_SYMBOL(input_set_poll_interval);
111 
input_set_min_poll_interval(struct input_dev * dev,unsigned int interval)112 void input_set_min_poll_interval(struct input_dev *dev, unsigned int interval)
113 {
114 	if (input_dev_ensure_poller(dev))
115 		dev->poller->poll_interval_min = interval;
116 }
117 EXPORT_SYMBOL(input_set_min_poll_interval);
118 
input_set_max_poll_interval(struct input_dev * dev,unsigned int interval)119 void input_set_max_poll_interval(struct input_dev *dev, unsigned int interval)
120 {
121 	if (input_dev_ensure_poller(dev))
122 		dev->poller->poll_interval_max = interval;
123 }
124 EXPORT_SYMBOL(input_set_max_poll_interval);
125 
input_get_poll_interval(struct input_dev * dev)126 int input_get_poll_interval(struct input_dev *dev)
127 {
128 	if (!dev->poller)
129 		return -EINVAL;
130 
131 	return dev->poller->poll_interval;
132 }
133 EXPORT_SYMBOL(input_get_poll_interval);
134 
135 /* SYSFS interface */
136 
input_dev_get_poll_interval(struct device * dev,struct device_attribute * attr,char * buf)137 static ssize_t input_dev_get_poll_interval(struct device *dev,
138 					   struct device_attribute *attr,
139 					   char *buf)
140 {
141 	struct input_dev *input = to_input_dev(dev);
142 
143 	return sprintf(buf, "%d\n", input->poller->poll_interval);
144 }
145 
input_dev_set_poll_interval(struct device * dev,struct device_attribute * attr,const char * buf,size_t count)146 static ssize_t input_dev_set_poll_interval(struct device *dev,
147 					   struct device_attribute *attr,
148 					   const char *buf, size_t count)
149 {
150 	struct input_dev *input = to_input_dev(dev);
151 	struct input_dev_poller *poller = input->poller;
152 	unsigned int interval;
153 	int err;
154 
155 	err = kstrtouint(buf, 0, &interval);
156 	if (err)
157 		return err;
158 
159 	if (interval < poller->poll_interval_min)
160 		return -EINVAL;
161 
162 	if (interval > poller->poll_interval_max)
163 		return -EINVAL;
164 
165 	mutex_lock(&input->mutex);
166 
167 	poller->poll_interval = interval;
168 
169 	if (input_device_enabled(input)) {
170 		cancel_delayed_work_sync(&poller->work);
171 		if (poller->poll_interval > 0)
172 			input_dev_poller_queue_work(poller);
173 	}
174 
175 	mutex_unlock(&input->mutex);
176 
177 	return count;
178 }
179 
180 static DEVICE_ATTR(poll, 0644,
181 		   input_dev_get_poll_interval, input_dev_set_poll_interval);
182 
input_dev_get_poll_max(struct device * dev,struct device_attribute * attr,char * buf)183 static ssize_t input_dev_get_poll_max(struct device *dev,
184 				      struct device_attribute *attr, char *buf)
185 {
186 	struct input_dev *input = to_input_dev(dev);
187 
188 	return sprintf(buf, "%d\n", input->poller->poll_interval_max);
189 }
190 
191 static DEVICE_ATTR(max, 0444, input_dev_get_poll_max, NULL);
192 
input_dev_get_poll_min(struct device * dev,struct device_attribute * attr,char * buf)193 static ssize_t input_dev_get_poll_min(struct device *dev,
194 				     struct device_attribute *attr, char *buf)
195 {
196 	struct input_dev *input = to_input_dev(dev);
197 
198 	return sprintf(buf, "%d\n", input->poller->poll_interval_min);
199 }
200 
201 static DEVICE_ATTR(min, 0444, input_dev_get_poll_min, NULL);
202 
input_poller_attrs_visible(struct kobject * kobj,struct attribute * attr,int n)203 static umode_t input_poller_attrs_visible(struct kobject *kobj,
204 					  struct attribute *attr, int n)
205 {
206 	struct device *dev = kobj_to_dev(kobj);
207 	struct input_dev *input = to_input_dev(dev);
208 
209 	return input->poller ? attr->mode : 0;
210 }
211 
212 static struct attribute *input_poller_attrs[] = {
213 	&dev_attr_poll.attr,
214 	&dev_attr_max.attr,
215 	&dev_attr_min.attr,
216 	NULL
217 };
218 
219 struct attribute_group input_poller_attribute_group = {
220 	.is_visible	= input_poller_attrs_visible,
221 	.attrs		= input_poller_attrs,
222 };
223