[PATCH] Input: Add ioctl to block suspend while event queue is not empty.

["Arve Hjønnevåg" <arve@android.com>]

Add an ioctl, EVIOCSSUSPENDBLOCK, to block suspend while the event
queue is not empty. This allows userspace code to process input
events while the device appears to be asleep.

Signed-off-by: Arve Hjønnevåg <arve@android.com>
---
 drivers/input/evdev.c |   63 +++++++++++++++++++++++++++++++++++++++++++++++++
 include/linux/input.h |    3 ++
 2 files changed, 66 insertions(+), 0 deletions(-)

diff --git a/drivers/input/evdev.c b/drivers/input/evdev.c
index 76457d5..e212757 100644
--- a/drivers/input/evdev.c
+++ b/drivers/input/evdev.c
@@ -43,6 +43,7 @@ struct evdev_client {
 	unsigned int tail;
 	unsigned int packet_head; /* [future] position of the first element of next packet */
 	spinlock_t buffer_lock; /* protects access to buffer, head and tail */
+	struct wakeup_source *wakeup_source;
 	struct fasync_struct *fasync;
 	struct evdev *evdev;
 	struct list_head node;
@@ -75,10 +76,14 @@ static void evdev_pass_event(struct evdev_client *client,
 		client->buffer[client->tail].value = 0;
 
 		client->packet_head = client->tail;
+		if (client->wakeup_source)
+			__pm_relax(client->wakeup_source);
 	}
 
 	if (event->type == EV_SYN && event->code == SYN_REPORT) {
 		client->packet_head = client->head;
+		if (client->wakeup_source)
+			__pm_stay_awake(client->wakeup_source);
 		kill_fasync(&client->fasync, SIGIO, POLL_IN);
 	}
 
@@ -255,6 +260,10 @@ static int evdev_release(struct inode *inode, struct file *file)
 	mutex_unlock(&evdev->mutex);
 
 	evdev_detach_client(evdev, client);
+	if (client->wakeup_source) {
+		__pm_relax(client->wakeup_source);
+		wakeup_source_unregister(client->wakeup_source);
+	}
 	kfree(client);
 
 	evdev_close_device(evdev);
@@ -373,6 +382,9 @@ static int evdev_fetch_next_event(struct evdev_client *client,
 	if (have_event) {
 		*event = client->buffer[client->tail++];
 		client->tail &= client->bufsize - 1;
+		if (client->wakeup_source &&
+		    client->packet_head == client->tail)
+			__pm_relax(client->wakeup_source);
 	}
 
 	spin_unlock_irq(&client->buffer_lock);
@@ -623,6 +635,48 @@ static int evdev_handle_set_keycode_v2(struct input_dev *dev, void __user *p)
 	return input_set_keycode(dev, &ke);
 }
 
+static int evdev_enable_suspend_block(struct evdev *evdev,
+				      struct evdev_client *client)
+{
+	struct wakeup_source *ws;
+	char name[28];
+
+	if (client->wakeup_source)
+		return 0;
+
+	snprintf(name, sizeof(name), "%s-%d",
+		 dev_name(&evdev->dev), task_tgid_vnr(current));
+
+	ws = wakeup_source_register(name);
+	if (!ws)
+		return -ENOMEM;
+
+	spin_lock_irq(&client->buffer_lock);
+	client->wakeup_source = ws;
+	if (client->packet_head != client->tail)
+		__pm_stay_awake(client->wakeup_source);
+	spin_unlock_irq(&client->buffer_lock);
+	return 0;
+}
+
+static int evdev_disable_suspend_block(struct evdev *evdev,
+				       struct evdev_client *client)
+{
+	struct wakeup_source *ws;
+
+	spin_lock_irq(&client->buffer_lock);
+	ws = client->wakeup_source;
+	client->wakeup_source = NULL;
+	spin_unlock_irq(&client->buffer_lock);
+
+	if (ws) {
+		__pm_relax(ws);
+		wakeup_source_unregister(ws);
+	}
+
+	return 0;
+}
+
 static long evdev_do_ioctl(struct file *file, unsigned int cmd,
 			   void __user *p, int compat_mode)
 {
@@ -696,6 +750,15 @@ static long evdev_do_ioctl(struct file *file, unsigned int cmd,
 
 	case EVIOCSKEYCODE_V2:
 		return evdev_handle_set_keycode_v2(dev, p);
+
+	case EVIOCGSUSPENDBLOCK:
+		return put_user(!!client->wakeup_source, ip);
+
+	case EVIOCSSUSPENDBLOCK:
+		if (p)
+			return evdev_enable_suspend_block(evdev, client);
+		else
+			return evdev_disable_suspend_block(evdev, client);
 	}
 
 	size = _IOC_SIZE(cmd);
diff --git a/include/linux/input.h b/include/linux/input.h
index 3862e32..daf0177 100644
--- a/include/linux/input.h
+++ b/include/linux/input.h
@@ -129,6 +129,9 @@ struct input_keymap_entry {
 
 #define EVIOCGRAB		_IOW('E', 0x90, int)			/* Grab/Release device */
 
+#define EVIOCGSUSPENDBLOCK	_IOR('E', 0x91, int)			/* get suspend block enable */
+#define EVIOCSSUSPENDBLOCK	_IOW('E', 0x91, int)			/* set suspend block enable */
+
 /*
  * Device properties and quirks
  */
-- 
1.7.7.3

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