[PATCH 1/2] Input: Add a helper for reporting a screen lock key sequence

[Mario Limonciello <superm1@kernel.org>]

From: Mario Limonciello <mario.limonciello@amd.com>

In the PC industry KEY_SCREENLOCK isn't used as frequently as it used
to be. Modern versions of Windows [1], GNOME and KDE support "META" + "L"
to lock the screen. Modern hardware [2] also sends this sequence of
events for keys with a silkscreen for screen lock.

Introduced a helper input_report_lock_sequence() for drivers to utilize
if they want to send this sequence.

Link: https://support.microsoft.com/en-us/windows/keyboard-shortcuts-in-windows-dcc61a57-8ff0-cffe-9796-cb9706c75eec [1]
Link: https://www.logitech.com/en-us/shop/p/k860-split-ergonomic.920-009166 [2]
Suggested-by: Armin Wolf <W_Armin@gmx.de>
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
---
 drivers/input/input.c | 20 ++++++++++++++++++++
 include/linux/input.h |  2 ++
 2 files changed, 22 insertions(+)

diff --git a/drivers/input/input.c b/drivers/input/input.c
index ec4346f20efdd..dfeace85c4710 100644
--- a/drivers/input/input.c
+++ b/drivers/input/input.c
@@ -508,6 +508,26 @@ void input_copy_abs(struct input_dev *dst, unsigned int dst_axis,
 }
 EXPORT_SYMBOL(input_copy_abs);
 
+/**
+ * input_report_lock_sequence - Report key combination to lock the screen
+ * @dev: input device
+ *
+ * Key combination used in the PC industry since Windows 7 for locking display
+ * is META + L. This is also used in GNOME and KDE by default.
+ * See https://support.microsoft.com/en-us/windows/keyboard-shortcuts-in-windows-dcc61a57-8ff0-cffe-9796-cb9706c75eec
+ */
+void input_report_lock_sequence(struct input_dev *dev)
+{
+	input_report_key(dev, KEY_LEFTMETA, 1);
+	input_report_key(dev, KEY_L, 1);
+	input_sync(dev);
+	input_report_key(dev, KEY_L, 0);
+	input_sync(dev);
+	input_report_key(dev, KEY_LEFTMETA, 0);
+	input_sync(dev);
+}
+EXPORT_SYMBOL(input_report_lock_sequence);
+
 /**
  * input_grab_device - grabs device for exclusive use
  * @handle: input handle that wants to own the device
diff --git a/include/linux/input.h b/include/linux/input.h
index 7d7cb0593a63e..16f7bef12f1c1 100644
--- a/include/linux/input.h
+++ b/include/linux/input.h
@@ -492,6 +492,8 @@ void input_set_abs_params(struct input_dev *dev, unsigned int axis,
 void input_copy_abs(struct input_dev *dst, unsigned int dst_axis,
 		    const struct input_dev *src, unsigned int src_axis);
 
+void input_report_lock_sequence(struct input_dev *dev);
+
 #define INPUT_GENERATE_ABS_ACCESSORS(_suffix, _item)			\
 static inline int input_abs_get_##_suffix(struct input_dev *dev,	\
 					  unsigned int axis)		\
-- 
2.43.0