[PATCH] HID: asus: Add support for Fn keys on Asus ROG G752

["Maxime Bellengé" <maxime.bellenge@gmail.com>]

This patch adds support for Fn keys on Asus ROG G752 laptop.
The report descriptor is broken so I fixed it.

Tested on an Asus G752VT.

Signed-off-by: Maxime Bellengé <maxime.bellenge@gmail.com>
---
 drivers/hid/hid-asus.c | 29 +++++++++++++++++++++++++++++
 drivers/hid/hid-core.c |  2 +-
 drivers/hid/hid-ids.h  |  1 +
 3 files changed, 31 insertions(+), 1 deletion(-)

diff --git a/drivers/hid/hid-asus.c b/drivers/hid/hid-asus.c
index a4a3c38bc145..2a03ed842186 100644
--- a/drivers/hid/hid-asus.c
+++ b/drivers/hid/hid-asus.c
@@ -70,6 +70,7 @@ MODULE_DESCRIPTION("Asus HID Keyboard and TouchPad");
 #define QUIRK_NO_CONSUMER_USAGES	BIT(4)
 #define QUIRK_USE_KBD_BACKLIGHT		BIT(5)
 #define QUIRK_T100_KEYBOARD		BIT(6)
+#define QUIRK_G752_KEYBOARD		BIT(7)
 
 #define I2C_KEYBOARD_QUIRKS			(QUIRK_FIX_NOTEBOOK_REPORT | \
 						 QUIRK_NO_INIT_REPORTS | \
@@ -568,6 +569,11 @@ static void asus_remove(struct hid_device *hdev)
 	hid_hw_stop(hdev);
 }
 
+static const __u8 asus_g752_fixed_rdesc[] = {
+        0x19, 0x00,                     /*   Usage Minimum (0x00)       */
+        0x2A, 0xFF, 0x00,               /*   Usage Maximum (0xFF)       */
+};
+
 static __u8 *asus_report_fixup(struct hid_device *hdev, __u8 *rdesc,
 		unsigned int *rsize)
 {
@@ -583,6 +589,27 @@ static __u8 *asus_report_fixup(struct hid_device *hdev, __u8 *rdesc,
 		hid_info(hdev, "Fixing up Asus T100 keyb report descriptor\n");
 		rdesc[74] &= ~HID_MAIN_ITEM_CONSTANT;
 	}
+        if (drvdata->quirks & QUIRK_G752_KEYBOARD &&
+		 *rsize == 75 && rdesc[61] == 0x15 && rdesc[62] == 0x00) {
+                /* report is missing usage mninum and maximum */
+                __u8 *new_rdesc;
+                size_t new_size = *rsize + sizeof(asus_g752_fixed_rdesc);
+
+                new_rdesc = devm_kzalloc(&hdev->dev, new_size, GFP_KERNEL);
+                if (new_rdesc == NULL)
+			return rdesc;
+
+                hid_info(hdev, "Fixing up Asus G752 keyb report descriptor\n");
+                /* copy the valid part */
+                memcpy(new_rdesc, rdesc, 61);
+                /* insert missing part */
+                memcpy(new_rdesc + 61, asus_g752_fixed_rdesc, sizeof(asus_g752_fixed_rdesc));
+                /* copy remaining data */
+                memcpy(new_rdesc + 61 + sizeof(asus_g752_fixed_rdesc), rdesc + 61, *rsize - 61);
+
+                *rsize = new_size;
+                rdesc = new_rdesc;
+	}
 
 	return rdesc;
 }
@@ -596,6 +623,8 @@ static const struct hid_device_id asus_devices[] = {
 		USB_DEVICE_ID_ASUSTEK_ROG_KEYBOARD1) },
 	{ HID_USB_DEVICE(USB_VENDOR_ID_ASUSTEK,
 		USB_DEVICE_ID_ASUSTEK_ROG_KEYBOARD2), QUIRK_USE_KBD_BACKLIGHT },
+        { HID_USB_DEVICE(USB_VENDOR_ID_ASUSTEK,
+                USB_DEVICE_ID_ASUSTEK_ROG_KEYBOARD3), QUIRK_G752_KEYBOARD },
 	{ HID_USB_DEVICE(USB_VENDOR_ID_ASUSTEK,
 		USB_DEVICE_ID_ASUSTEK_T100_KEYBOARD),
 	  QUIRK_T100_KEYBOARD | QUIRK_NO_CONSUMER_USAGES },
diff --git a/drivers/hid/hid-core.c b/drivers/hid/hid-core.c
index 9017dcc14502..45369f5dad6e 100644
--- a/drivers/hid/hid-core.c
+++ b/drivers/hid/hid-core.c
@@ -1979,6 +1979,7 @@ static const struct hid_device_id hid_have_special_driver[] = {
 	{ HID_I2C_DEVICE(USB_VENDOR_ID_ASUSTEK, USB_DEVICE_ID_ASUSTEK_I2C_TOUCHPAD) },
 	{ HID_USB_DEVICE(USB_VENDOR_ID_ASUSTEK, USB_DEVICE_ID_ASUSTEK_ROG_KEYBOARD1) },
 	{ HID_USB_DEVICE(USB_VENDOR_ID_ASUSTEK, USB_DEVICE_ID_ASUSTEK_ROG_KEYBOARD2) },
+        { HID_USB_DEVICE(USB_VENDOR_ID_ASUSTEK, USB_DEVICE_ID_ASUSTEK_ROG_KEYBOARD3) },
 	{ HID_USB_DEVICE(USB_VENDOR_ID_ASUSTEK, USB_DEVICE_ID_ASUSTEK_T100_KEYBOARD) },
 	{ HID_USB_DEVICE(USB_VENDOR_ID_JESS, USB_DEVICE_ID_ASUS_MD_5112) },
 	{ HID_USB_DEVICE(USB_VENDOR_ID_TURBOX, USB_DEVICE_ID_ASUS_MD_5110) },
@@ -3125,4 +3126,3 @@ MODULE_AUTHOR("Andreas Gal");
 MODULE_AUTHOR("Vojtech Pavlik");
 MODULE_AUTHOR("Jiri Kosina");
 MODULE_LICENSE("GPL");
-
diff --git a/drivers/hid/hid-ids.h b/drivers/hid/hid-ids.h
index c9ba4c6db74c..602409663743 100644
--- a/drivers/hid/hid-ids.h
+++ b/drivers/hid/hid-ids.h
@@ -180,6 +180,7 @@
 #define USB_DEVICE_ID_ASUSTEK_I2C_TOUCHPAD	0x0101
 #define USB_DEVICE_ID_ASUSTEK_ROG_KEYBOARD1 0x1854
 #define USB_DEVICE_ID_ASUSTEK_ROG_KEYBOARD2 0x1837
+#define USB_DEVICE_ID_ASUSTEK_ROG_KEYBOARD3 0x1822
 
 #define USB_VENDOR_ID_ATEN		0x0557
 #define USB_DEVICE_ID_ATEN_UC100KM	0x2004
-- 
2.13.5