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
 15struct 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
 26static 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
 37static 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
 46void 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
 54void 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
 63void input_dev_poller_stop(struct input_dev_poller *poller)
 64{
 65	cancel_delayed_work_sync(&poller->work);
 66}
 67
 68int 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}
 92EXPORT_SYMBOL(input_setup_polling);
 93
 94static 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
105void 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}
110EXPORT_SYMBOL(input_set_poll_interval);
111
112void 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}
117EXPORT_SYMBOL(input_set_min_poll_interval);
118
119void 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}
124EXPORT_SYMBOL(input_set_max_poll_interval);
125
126int input_get_poll_interval(struct input_dev *dev)
127{
128	if (!dev->poller)
129		return -EINVAL;
130
131	return dev->poller->poll_interval;
132}
133EXPORT_SYMBOL(input_get_poll_interval);
134
135/* SYSFS interface */
136
137static 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
146static 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
180static DEVICE_ATTR(poll, 0644,
181		   input_dev_get_poll_interval, input_dev_set_poll_interval);
182
183static 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
191static DEVICE_ATTR(max, 0444, input_dev_get_poll_max, NULL);
192
193static 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
201static DEVICE_ATTR(min, 0444, input_dev_get_poll_min, NULL);
202
203static 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
212static struct attribute *input_poller_attrs[] = {
213	&dev_attr_poll.attr,
214	&dev_attr_max.attr,
215	&dev_attr_min.attr,
216	NULL
217};
218
219struct attribute_group input_poller_attribute_group = {
220	.is_visible	= input_poller_attrs_visible,
221	.attrs		= input_poller_attrs,
222};