[PATCH v2 2/2] platform/x86: msi-wmi: Add MSI Claw M-Center keys

["Derek J. Clark" <derekjohn.clark@gmail.com>]

MSI Claw devices produce WMI events through the MSI WMI hotkeys GUID for
some of their buttons. When pressed, these cause spam in the kernel. For
the majority of devices these events can be safely ignored as they are
duplicated by the AT Translated Set 2 Keyboard device exposed as an
evdev. For the MSI Claw A8 BZ2EM model's M-Center Menu button (left of
the screen) there is no associated keyboard event, so this event must be
exposed. Map this button to the same scancode produced by the AT
Keyboard device on other models. This does cause double F15 events on
the A1M, 7 AI+ A2VM, and 8 AI+ A2VM, but it appears to be harmless in my
testing.

Signed-off-by: Derek J. Clark <derekjohn.clark@gmail.com>
---
v2:
  - Add comments explaining buffer fields & length.
  - Test that we have at lease u8[2] before assignment of key ID
---
 drivers/platform/x86/msi-wmi.c | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)

diff --git a/drivers/platform/x86/msi-wmi.c b/drivers/platform/x86/msi-wmi.c
index d00ced756581..c9db750fe5ae 100644
--- a/drivers/platform/x86/msi-wmi.c
+++ b/drivers/platform/x86/msi-wmi.c
@@ -46,6 +46,12 @@ enum msi_scancodes {
 	WIND_KEY_WLAN		= 0x5f,	/* Fn+F11 Wi-Fi toggle */
 	WIND_KEY_TURBO,			/* Fn+F10 turbo mode toggle */
 	WIND_KEY_ECO		= 0x69,	/* Fn+F10 ECO mode toggle */
+	/* MSI Claw keys */
+	CLAW_KEY_VOLUMEDOWN	= 0x21,
+	CLAW_KEY_CENTER		= 0x29,	/* MSI M-Center main menu */
+	CLAW_KEY_QUICK_LONG	= 0x2a,	/* MSI M-Center quick access long hold */
+	CLAW_KEY_VOLUMEUP	= 0x32,
+	CLAW_KEY_QUICK_SHORT	= 0x58,	/* MSI M-Center quick access short press */
 };
 static struct key_entry msi_wmi_keymap[] = {
 	{ KE_KEY, MSI_KEY_BRIGHTNESSUP,		{KEY_BRIGHTNESSUP} },
@@ -69,6 +75,15 @@ static struct key_entry msi_wmi_keymap[] = {
 	{ KE_KEY, WIND_KEY_TURBO,		{KEY_PROG1} },
 	{ KE_KEY, WIND_KEY_ECO,			{KEY_PROG2} },
 
+	/* These are MSI Claw keys, used for MSI M-Center in Windows */
+	{ KE_KEY, CLAW_KEY_CENTER,		{KEY_F15} },
+
+	/* These MSI Claw keys work without WMI. Ignore them to avoid double keycodes */
+	{ KE_IGNORE, CLAW_KEY_QUICK_SHORT },
+	{ KE_IGNORE, CLAW_KEY_QUICK_LONG },
+	{ KE_IGNORE, CLAW_KEY_VOLUMEUP },
+	{ KE_IGNORE, CLAW_KEY_VOLUMEDOWN },
+
 	{ KE_END, 0 }
 };
 
@@ -183,6 +198,17 @@ static void msi_wmi_notify(union acpi_object *obj, void *context)
 		eventcode = obj->integer.value;
 		pr_debug("Eventcode: 0x%x\n", eventcode);
 		break;
+	case ACPI_TYPE_BUFFER:
+		/* Field returns u8[2] here, but is u32 by spec. Allow "oversized" buffers. */
+		if (obj->buffer.length < 2)
+			return;
+
+		/* pointer[0] is key ID, pointer[1] is active state. We don't get release
+		 * events, so ignore the active state and treat as autorelease.
+		 */
+		eventcode = obj->buffer.pointer[0];
+		pr_debug("Eventcode: 0x%x\n", eventcode);
+		break;
 	default:
 		pr_info("Unknown event received\n");
 		return;
-- 
2.54.0