platform/x86: dell-wmi-base: Handle electronic privacy screen on/off events

Add handling for events for the electronic privacy screen found on some
models (e.g. Dell Latitude 7300) being toggled on/off.

Emit KEY_EPRIVACY_SCREEN_OFF / KEY_EPRIVACY_SCREEN_ON events for this so
that userspace can show the usual on-screen-display (OSD) notification for
eprivacy screen on/off to the user.

Signed-off-by: Hans de Goede <[email protected]>
Link: https://patch.msgid.link/[email protected]
Reviewed-by: Ilpo Järvinen <[email protected]>
Signed-off-by: Ilpo Järvinen <[email protected]>

Author: Hans de Goede

drivers/platform/x86/dell/dell-wmi-base.c

@@ -365,6 +365,13 @@ static const struct key_entry dell_wmi_keymap_type_0012[] = {
 	/* Backlight brightness change event */
 	{ KE_IGNORE, 0x0003, { KEY_RESERVED } },
 
+	/*
+	 * Electronic privacy screen toggled, extended data gives state,
+	 * separate entries for on/off see handling in dell_wmi_process_key().
+	 */
+	{ KE_KEY, 0x000c, { KEY_EPRIVACY_SCREEN_OFF } },
+	{ KE_KEY, 0x000c, { KEY_EPRIVACY_SCREEN_ON } },
+
 	/* Ultra-performance mode switch request */
 	{ KE_IGNORE, 0x000d, { KEY_RESERVED } },
 
@@ -435,6 +442,11 @@ static int dell_wmi_process_key(struct wmi_device *wdev, int type, int code, u16
 				      "Dell tablet mode switch",
 				      SW_TABLET_MODE, !buffer[0]);
 		return 1;
+	} else if (type == 0x0012 && code == 0x000c && remaining > 0) {
+		/* Eprivacy toggle, switch to "on" key entry for on events */
+		if (buffer[0] == 2)
+			key++;
+		used = 1;
 	} else if (type == 0x0012 && code == 0x000d && remaining > 0) {
 		value = (buffer[2] == 2);
 		used = 1;