[PATCH v3 1/2] Input: Add a Kconfig to emulate KEY_SCREENLOCK with META + L

[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 new Kconfig option that will change KEY_SCREENLOCK when
emitted by driver to META + L.

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>
---
v3:
 * Emulation in the input core instead

 drivers/input/Kconfig |  8 ++++++++
 drivers/input/input.c | 19 +++++++++++++++++++
 2 files changed, 27 insertions(+)

diff --git a/drivers/input/Kconfig b/drivers/input/Kconfig
index 88ecdf5218ee9..ffb4163fe315f 100644
--- a/drivers/input/Kconfig
+++ b/drivers/input/Kconfig
@@ -174,6 +174,14 @@ config INPUT_APMPOWER
 	  To compile this driver as a module, choose M here: the
 	  module will be called apm-power.
 
+config INPUT_SCREENLOCK_EMULATION
+	bool "Pass KEY_SCREENLOCK as META + L"
+	help
+	  Say Y here if you want KEY_SCREENLOCK to be passed to userspace as
+	  META + L.
+
+	  If unsure, say Y.
+
 comment "Input Device Drivers"
 
 source "drivers/input/keyboard/Kconfig"
diff --git a/drivers/input/input.c b/drivers/input/input.c
index dfeace85c4710..08a857cea0c5d 100644
--- a/drivers/input/input.c
+++ b/drivers/input/input.c
@@ -370,6 +370,13 @@ void input_handle_event(struct input_dev *dev,
 	}
 }
 
+static void handle_screenlock_as_meta_l(struct input_dev *dev, unsigned int type,
+					int value)
+{
+	input_handle_event(dev, type, KEY_LEFTMETA, value);
+	input_handle_event(dev, type, KEY_L, value);
+}
+
 /**
  * input_event() - report new input event
  * @dev: device that generated the event
@@ -392,6 +399,12 @@ void input_event(struct input_dev *dev,
 {
 	if (is_event_supported(type, dev->evbit, EV_MAX)) {
 		guard(spinlock_irqsave)(&dev->event_lock);
+#ifdef CONFIG_INPUT_SCREENLOCK_EMULATION
+		if (code == KEY_SCREENLOCK) {
+			handle_screenlock_as_meta_l(dev, type, value);
+			return;
+		}
+#endif
 		input_handle_event(dev, type, code, value);
 	}
 }
@@ -2134,6 +2147,12 @@ void input_set_capability(struct input_dev *dev, unsigned int type, unsigned int
 
 	switch (type) {
 	case EV_KEY:
+#ifdef CONFIG_INPUT_SCREENLOCK_EMULATION
+		if (code == KEY_SCREENLOCK) {
+			__set_bit(KEY_L, dev->keybit);
+			__set_bit(KEY_LEFTMETA, dev->keybit);
+		}
+#endif
 		__set_bit(code, dev->keybit);
 		break;
 
-- 
2.43.0