platform/x86: thinkpad_acpi: Support for trackpoint doubletap

Lenovo trackpoints are adding the ability to generate a doubletap event.
This handles the doubletap event and sends the KEY_PROG4 event to
userspace. Despite the driver itself not using KEY_PROG1 - KEY_PROG3 this
still uses KEY_PROG4 because of some keys being remapped to KEY_PROG1 -
KEY_PROG3 by default by the upstream udev hwdb containing:

evdev:name:ThinkPad Extra Buttons:dmi:bvn*:bvr*:bd*:svnLENOVO*:pn*:*
 ...
 KEYBOARD_KEY_17=prog1
 KEYBOARD_KEY_1a=f20       # Microphone mute button
 KEYBOARD_KEY_45=bookmarks
 KEYBOARD_KEY_46=prog2     # Fn + PrtSc, on Windows: Snipping tool
 KEYBOARD_KEY_4a=prog3     # Fn + Right shift, on Windows: No idea
Signed-off-by: Mark Pearson <mpearson-lenovo@squebb.ca>
Signed-off-by: Vishnu Sankar <vishnuocv@gmail.com>
Link: https://lore.kernel.org/r/20240417173124.9953-2-mpearson-lenovo@squebb.ca
[hdegoede@redhat.com: Adjust for switch to sparse-keymap keymaps]
Tested-by: Mark Pearson <mpearson-lenovo@squebb.ca>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Mark Pearson <mpearson-lenovo@squebb.ca>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20240424122834.19801-23-hdegoede@redhat.com

drivers/platform/x86/thinkpad_acpi.c

@@ -248,6 +248,9 @@ enum tpacpi_hkey_event_t {
 
 	/* Misc */
 	TP_HKEY_EV_RFKILL_CHANGED	= 0x7000, /* rfkill switch changed */
+
+	/* Misc2 */
+	TP_HKEY_EV_TRACK_DOUBLETAP      = 0x8036, /* trackpoint doubletap */
 };
 
 /****************************************************************************
@@ -3268,6 +3271,7 @@ static const struct key_entry keymap_lenovo[] __initconst = {
 	 * after switching to sparse keymap support. The mappings above use translated
 	 * scancodes to preserve uAPI compatibility, see tpacpi_input_send_key().
 	 */
+	{ KE_KEY, TP_HKEY_EV_TRACK_DOUBLETAP /* 0x8036 */, { KEY_PROG4 } },
 	{ KE_END }
 };
 
@@ -3817,6 +3821,17 @@ static bool hotkey_notify_6xxx(const u32 hkey, bool *send_acpi_ev)
 	return true;
 }
 
+static bool hotkey_notify_8xxx(const u32 hkey, bool *send_acpi_ev)
+{
+	switch (hkey) {
+	case TP_HKEY_EV_TRACK_DOUBLETAP:
+		tpacpi_input_send_key(hkey, send_acpi_ev);
+		return true;
+	default:
+		return false;
+	}
+}
+
 static void hotkey_notify(struct ibm_struct *ibm, u32 event)
 {
 	u32 hkey;
@@ -3893,6 +3908,10 @@ static void hotkey_notify(struct ibm_struct *ibm, u32 event)
 				known_ev = true;
 			}
 			break;
+		case 8:
+			/* 0x8000-0x8FFF: misc2 */
+			known_ev = hotkey_notify_8xxx(hkey, &send_acpi_ev);
+			break;
 		}
 		if (!known_ev) {
 			pr_notice("unhandled HKEY event 0x%04x\n", hkey);