[PATCH 1/1] Input polldev: Sysfs interface for setting of polling interval

[Samu Onkalo <samu.p.onkalo@xxxxxxxxx>]

Sysfs entry for reading and setting of the polling interval.
If the interval is set to 0, polling is stopped. Polling
is restarted when interval is changed to non-zero.

Minimum and maximum limit for interval can be set while setting up the
device.

Interval can be adjusted even if the input device is not currently open.

applicable to Dmitry Torokhov's input-tree->next
(git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input.git->next)

Signed-off-by: Samu Onkalo <samu.p.onkalo@xxxxxxxxx>
---
 drivers/input/input-polldev.c |   86 +++++++++++++++++++++++++++++++++++++++--
 include/linux/input-polldev.h |    3 +
 2 files changed, 85 insertions(+), 4 deletions(-)

diff --git a/drivers/input/input-polldev.c b/drivers/input/input-polldev.c
index 910220c..5d7fffd 100644
--- a/drivers/input/input-polldev.c
+++ b/drivers/input/input-polldev.c
@@ -46,10 +46,12 @@ static int input_polldev_start_workqueue(void)
 	return retval;
 }
 
-static void input_polldev_stop_workqueue(void)
+static void input_polldev_stop_workqueue(struct input_polled_dev *dev)
 {
 	mutex_lock(&polldev_mutex);
 
+	cancel_delayed_work_sync(&dev->work);
+
 	if (!--polldev_users)
 		destroy_workqueue(polldev_wq);
 
@@ -83,6 +85,8 @@ static int input_open_polled_device(struct input_dev *input)
 	if (dev->open)
 		dev->open(dev);
 
+	dev->is_opened = 1;
+
 	queue_delayed_work(polldev_wq, &dev->work,
 			   msecs_to_jiffies(dev->poll_interval));
 
@@ -93,13 +97,72 @@ static void input_close_polled_device(struct input_dev *input)
 {
 	struct input_polled_dev *dev = input_get_drvdata(input);
 
-	cancel_delayed_work_sync(&dev->work);
-	input_polldev_stop_workqueue();
+	dev->is_opened = 0;
+	input_polldev_stop_workqueue(dev);
 
 	if (dev->close)
 		dev->close(dev);
 }
 
+/* SYSFS interface */
+
+static ssize_t input_polldev_get_interval(struct device *dev,
+				    struct device_attribute *attr, char *buf)
+{
+	struct input_polled_dev *polldev = dev_get_drvdata(dev);
+
+	return sprintf(buf, "%d\n", polldev->poll_interval);
+}
+
+static ssize_t input_polldev_set_interval(struct device *dev,
+				struct device_attribute *attr, const char *buf,
+				size_t count)
+{
+	struct input_polled_dev *polldev = dev_get_drvdata(dev);
+	unsigned long delay;
+	unsigned long interval;
+
+	if (strict_strtoul(buf, 0, &interval))
+		return -EINVAL;
+
+	if (interval < polldev->poll_interval_min)
+		return -EINVAL;
+
+	if (interval > polldev->poll_interval_max)
+		return -EINVAL;
+
+	mutex_lock(&polldev_mutex);
+
+	polldev->poll_interval = interval;
+
+	if (polldev->is_opened) {
+		if (polldev->poll_interval > 0) {
+			delay = msecs_to_jiffies(polldev->poll_interval);
+			if (delay >= HZ)
+				delay = round_jiffies_relative(delay);
+
+			queue_delayed_work(polldev_wq, &polldev->work, delay);
+		} else {
+			cancel_delayed_work_sync(&polldev->work);
+		}
+	}
+	mutex_unlock(&polldev_mutex);
+
+	return count;
+}
+
+static DEVICE_ATTR(interval, S_IRUGO | S_IWUSR, input_polldev_get_interval,
+						input_polldev_set_interval);
+
+static struct attribute *sysfs_attrs[] = {
+	&dev_attr_interval.attr,
+	NULL
+};
+
+static struct attribute_group input_polldev_attribute_group = {
+	.attrs = sysfs_attrs
+};
+
 /**
  * input_allocate_polled_device - allocated memory polled device
  *
@@ -153,15 +216,27 @@ EXPORT_SYMBOL(input_free_polled_device);
 int input_register_polled_device(struct input_polled_dev *dev)
 {
 	struct input_dev *input = dev->input;
+	int error;
 
 	input_set_drvdata(input, dev);
 	INIT_DELAYED_WORK(&dev->work, input_polled_device_work);
 	if (!dev->poll_interval)
 		dev->poll_interval = 500;
+	if (!dev->poll_interval_max)
+		dev->poll_interval_max = dev->poll_interval;
 	input->open = input_open_polled_device;
 	input->close = input_close_polled_device;
 
-	return input_register_device(input);
+	error = input_register_device(input);
+	if (error < 0)
+		goto fail;
+
+	error = sysfs_create_group(&input->dev.kobj,
+				   &input_polldev_attribute_group);
+	if (error < 0)
+		input_unregister_device(input);
+fail:
+	return error;
 }
 EXPORT_SYMBOL(input_register_polled_device);
 
@@ -177,6 +252,9 @@ EXPORT_SYMBOL(input_register_polled_device);
  */
 void input_unregister_polled_device(struct input_polled_dev *dev)
 {
+	sysfs_remove_group(&dev->input->dev.kobj,
+			   &input_polldev_attribute_group);
+
 	input_unregister_device(dev->input);
 	dev->input = NULL;
 }
diff --git a/include/linux/input-polldev.h b/include/linux/input-polldev.h
index 5c0ec68..f2b1e03 100644
--- a/include/linux/input-polldev.h
+++ b/include/linux/input-polldev.h
@@ -36,6 +36,9 @@ struct input_polled_dev {
 	void (*close)(struct input_polled_dev *dev);
 	void (*poll)(struct input_polled_dev *dev);
 	unsigned int poll_interval; /* msec */
+	unsigned int poll_interval_max; /* msec */
+	unsigned int poll_interval_min; /* msec */
+	int is_opened;
 
 	struct input_dev *input;
 	struct delayed_work work;
-- 
1.5.6.3

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