[PATCH 5/7] hid-asus: Fix input mapping on dedicated vendor HID interfaces

[Paolo Pisati <p.pisati@gmail.com>]

From: Joshua Leivenzon <hacker1024@users.sourceforge.net>

Signed-off-by: Joshua Leivenzon <hacker1024@users.sourceforge.net>
---
 drivers/hid/hid-asus.c | 44 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 44 insertions(+)

diff --git a/drivers/hid/hid-asus.c b/drivers/hid/hid-asus.c
index cf9184ed2d3ec..fe52fd63d61c6 100644
--- a/drivers/hid/hid-asus.c
+++ b/drivers/hid/hid-asus.c
@@ -1376,6 +1376,30 @@ static void asus_remove(struct hid_device *hdev)
 	hid_hw_stop(hdev);
 }
 
+/*
+ * Some USB keyboards, like the Zenbook Duo UX8406MA keyboard, have a dedicated
+ * USB interface for vendor-specific reports, separate to the generic HID
+ * keyboard or consumer control interfaces.
+ *
+ * The kernel does not register these vendor-specific interfaces as keyboards,
+ * or perform input mapping on them at all.
+ *
+ * To work around this, a fake keyboard input can be added to the
+ * vendor-specific interface's report descriptor. The kernel then combines it
+ * with the vendor-specific collections, and allows the interface to be used as
+ * a regular keyboard with our custom mappings.
+ */
+static const __u8 asus_fake_keyboard_rdesc[] = {
+	0x05, 0x01, /* Usage Page (Generic Desktop) */
+	0x09, 0x06, /* Usage (Keyboard) */
+	0xa1, 0x01, /* Collection (Application) */
+	0x85, 0x01, /*   Report ID (1) */
+	0x75, 0x08, /*   Report Size (8) */
+	0x95, 0x01, /*   Report Count (1) */
+	0x81, 0x00, /*   Input (Data,Arr,Abs) */
+	0xc0,       /* End Collection */
+};
+
 static const __u8 asus_g752_fixed_rdesc[] = {
         0x19, 0x00,			/*   Usage Minimum (0x00)       */
         0x2A, 0xFF, 0x00,		/*   Usage Maximum (0xFF)       */
@@ -1457,6 +1481,26 @@ static const __u8 *asus_report_fixup(struct hid_device *hdev, __u8 *rdesc,
 		}
 	}
 
+	if ((drvdata->quirks & QUIRK_ZENBOOK_DUO_KEYBOARD) &&
+	    hid_is_usb(hdev) &&
+	    to_usb_interface(hdev->dev.parent)->altsetting->desc.bInterfaceNumber == 4) {
+
+		__u8 *new_rdesc;
+		size_t new_size = *rsize + sizeof(asus_fake_keyboard_rdesc);
+
+		new_rdesc = devm_kzalloc(&hdev->dev, new_size, GFP_KERNEL);
+		if (new_rdesc == NULL)
+			return rdesc;
+
+		hid_info(hdev, "Injecting virtual Zenbook Duo keyboard usage page\n");
+
+		memcpy(new_rdesc, asus_fake_keyboard_rdesc, sizeof(asus_fake_keyboard_rdesc));
+		memcpy(new_rdesc + sizeof(asus_fake_keyboard_rdesc), rdesc, *rsize);
+
+		*rsize = new_size;
+		rdesc = new_rdesc;
+	}
+
 	if (drvdata->quirks & QUIRK_G752_KEYBOARD &&
 		 *rsize == 75 && rdesc[61] == 0x15 && rdesc[62] == 0x00) {
 		/* report is missing usage minimum and maximum */
-- 
2.53.0