diff --git a/drivers/hid/Kconfig b/drivers/hid/Kconfig
index 4070b73..519918b 100644
--- a/drivers/hid/Kconfig
+++ b/drivers/hid/Kconfig
@@ -258,10 +258,12 @@ config HID_EMS_FF
 	 - Trio Linker Plus II
 
 config HID_ELECOM
-	tristate "ELECOM BM084 bluetooth mouse"
+	tristate "ELECOM HID devices"
 	depends on HID
 	---help---
-	Support for the ELECOM BM084 (bluetooth mouse).
+	Support for ELECOM devices:
+	  - BM084 Bluetooth Mouse
+	  - DEFT Trackball (Wired and wireless)
 
 config HID_ELO
 	tristate "ELO USB 4000/4500 touchscreen"
diff --git a/drivers/hid/hid-core.c b/drivers/hid/hid-core.c
index ea36b55..1bc9291 100644
--- a/drivers/hid/hid-core.c
+++ b/drivers/hid/hid-core.c
@@ -1891,6 +1891,8 @@ static const struct hid_device_id hid_have_special_driver[] = {
 	{ HID_USB_DEVICE(USB_VENDOR_ID_DREAM_CHEEKY, USB_DEVICE_ID_DREAM_CHEEKY_WN) },
 	{ HID_USB_DEVICE(USB_VENDOR_ID_DREAM_CHEEKY, USB_DEVICE_ID_DREAM_CHEEKY_FA) },
 	{ HID_BLUETOOTH_DEVICE(USB_VENDOR_ID_ELECOM, USB_DEVICE_ID_ELECOM_BM084) },
+	{ HID_USB_DEVICE(USB_VENDOR_ID_ELECOM, USB_DEVICE_ID_ELECOM_DEFT_WIRED) },
+	{ HID_USB_DEVICE(USB_VENDOR_ID_ELECOM, USB_DEVICE_ID_ELECOM_DEFT_WIRELESS) },
 	{ HID_USB_DEVICE(USB_VENDOR_ID_ELO, 0x0009) },
 	{ HID_USB_DEVICE(USB_VENDOR_ID_ELO, 0x0030) },
 	{ HID_USB_DEVICE(USB_VENDOR_ID_EMS, USB_DEVICE_ID_EMS_TRIO_LINKER_PLUS_II) },
diff --git a/drivers/hid/hid-elecom.c b/drivers/hid/hid-elecom.c
index 6e3848a..2081710 100644
--- a/drivers/hid/hid-elecom.c
+++ b/drivers/hid/hid-elecom.c
@@ -1,10 +1,8 @@
 /*
- *  HID driver for Elecom BM084 (bluetooth mouse).
- *  Removes a non-existing horizontal wheel from
- *  the HID descriptor.
- *  (This module is based on "hid-ortek".)
- *
+ *  HID driver for ELECOM devices.
  *  Copyright (c) 2010 Richard Nauber <Richard.Nauber@gmail.com>
+ *  Copyright (c) 2016 Yuxuan Shui <yshuiv7@gmail.com>
+ *  Copyright (c) 2017 Diego Elio Pettenò <flameeyes@flameeyes.eu>
  */
 
 /*
@@ -23,15 +21,59 @@
 static __u8 *elecom_report_fixup(struct hid_device *hdev, __u8 *rdesc,
 		unsigned int *rsize)
 {
-	if (*rsize >= 48 && rdesc[46] == 0x05 && rdesc[47] == 0x0c) {
-		hid_info(hdev, "Fixing up Elecom BM084 report descriptor\n");
-		rdesc[47] = 0x00;
+	switch (hdev->product) {
+	case USB_DEVICE_ID_ELECOM_BM084:
+		/* The BM084 Bluetooth mouse includes a non-existing horizontal
+		 * wheel in the HID descriptor. */
+		if (*rsize >= 48 && rdesc[46] == 0x05 && rdesc[47] == 0x0c) {
+			hid_info(hdev, "Fixing up Elecom BM084 report descriptor\n");
+			rdesc[47] = 0x00;
+		}
+	case USB_DEVICE_ID_ELECOM_DEFT_WIRED:
+	case USB_DEVICE_ID_ELECOM_DEFT_WIRELESS:
+		/* The DEFT trackball has eight buttons, but its descriptor only
+		 * reports five, disabling the three Fn buttons on the top of
+		 * the mouse.
+		 *
+		 * Apply the following diff to the descriptor:
+		 *
+		 * Collection (Physical),              Collection (Physical),
+		 *     Report ID (1),                      Report ID (1),
+		 *     Report Count (5),            |      Report Count (8),
+		 *     Report Size (1),                    Report Size (1),
+		 *     Usage Page (Button),                Usage Page (Button),
+		 *     Usage Minimum (01h),                Usage Minimum (01h),
+		 *     Usage Maximum (05h),         |      Usage Maximum (08h),
+		 *     Logical Minimum (0),                Logical Minimum (0),
+		 *     Logical Maximum (1),                Logical Maximum (1),
+		 *     Input (Variable),                   Input (Variable),
+		 *     Report Count (1),            |      Report Count (0),
+		 *     Report Size (3),                    Report Size (3),
+		 *     Input (Constant),                   Input (Constant),
+		 *     Report Size (16),                   Report Size (16),
+		 *     Report Count (2),                   Report Count (2),
+		 *     Usage Page (Desktop),               Usage Page (Desktop),
+		 *     Usage (X),                          Usage (X),
+		 *     Usage (Y),                          Usage (Y),
+		 *     Logical Minimum (-32768),           Logical Minimum (-32768),
+		 *     Logical Maximum (32767),            Logical Maximum (32767),
+		 *     Input (Variable, Relative),         Input (Variable, Relative),
+		 * End Collection,                     End Collection,
+		 */
+		if (*rsize == 213 && rdesc[13] == 5 && rdesc[21] == 5) {
+			hid_info(hdev, "Fixing up Elecom DEFT Fn buttons\n");
+			rdesc[13] = 8; /* Button/Variable Report Count */
+			rdesc[21] = 8; /* Button/Variable Usage Maximum */
+			rdesc[29] = 0; /* Button/Constant Report Count */
+		}
 	}
 	return rdesc;
 }
 
 static const struct hid_device_id elecom_devices[] = {
-	{ HID_BLUETOOTH_DEVICE(USB_VENDOR_ID_ELECOM, USB_DEVICE_ID_ELECOM_BM084)},
+	{ HID_BLUETOOTH_DEVICE(USB_VENDOR_ID_ELECOM, USB_DEVICE_ID_ELECOM_BM084) },
+	{ HID_USB_DEVICE(USB_VENDOR_ID_ELECOM, USB_DEVICE_ID_ELECOM_DEFT_WIRED) },
+	{ HID_USB_DEVICE(USB_VENDOR_ID_ELECOM, USB_DEVICE_ID_ELECOM_DEFT_WIRELESS) },
 	{ }
 };
 MODULE_DEVICE_TABLE(hid, elecom_devices);
diff --git a/drivers/hid/hid-ids.h b/drivers/hid/hid-ids.h
index 350accf..5f1635f 100644
--- a/drivers/hid/hid-ids.h
+++ b/drivers/hid/hid-ids.h
@@ -351,6 +351,8 @@
 
 #define USB_VENDOR_ID_ELECOM		0x056e
 #define USB_DEVICE_ID_ELECOM_BM084	0x0061
+#define USB_DEVICE_ID_ELECOM_DEFT_WIRED	0x00fe
+#define USB_DEVICE_ID_ELECOM_DEFT_WIRELESS	0x00ff
 
 #define USB_VENDOR_ID_DREAM_CHEEKY	0x1d34
 #define USB_DEVICE_ID_DREAM_CHEEKY_WN	0x0004
