// SPDX-License-Identifier: GPL-2.0-or-later

  /*

   *  HID driver for ELECOM devices:
   *  - BM084 Bluetooth Mouse

   *  - EX-G Trackballs (M-XT3DRBK, M-XT3URBK, M-XT4DRBK)

   *  - DEFT Trackballs (M-DT1DRBK, M-DT1URBK, M-DT2DRBK, M-DT2URBK)
   *  - HUGE Trackballs (M-HT1DRBK, M-HT1URBK)

   *

   *  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>

   *  Copyright (c) 2017 Alex Manoussakis <amanou@gnu.org>

   *  Copyright (c) 2017 Tomasz Kramkowski <tk@the-tk.com>

   */
  
  /*

   */
  
  #include <linux/device.h>
  #include <linux/hid.h>
  #include <linux/module.h>
  
  #include "hid-ids.h"

  /*
   * Certain ELECOM mice misreport their button count meaning that they only work
   * correctly with the ELECOM mouse assistant software which is unavailable for
   * Linux. A four extra INPUT reports and a FEATURE report are described by the
   * report descriptor but it does not appear that these enable software to
   * control what the extra buttons map to. The only simple and straightforward
   * solution seems to involve fixing up the report descriptor.
   *
   * Report descriptor format:
   * Positions 13, 15, 21 and 31 store the button bit count, button usage minimum,
   * button usage maximum and padding bit count respectively.
   */
  #define MOUSE_BUTTONS_MAX 8
  static void mouse_button_fixup(struct hid_device *hdev,
  			       __u8 *rdesc, unsigned int rsize,
  			       int nbuttons)
  {
  	if (rsize < 32 || rdesc[12] != 0x95 ||
  	    rdesc[14] != 0x75 || rdesc[15] != 0x01 ||
  	    rdesc[20] != 0x29 || rdesc[30] != 0x75)
  		return;
  	hid_info(hdev, "Fixing up Elecom mouse button count
  ");
  	nbuttons = clamp(nbuttons, 0, MOUSE_BUTTONS_MAX);
  	rdesc[13] = nbuttons;
  	rdesc[21] = nbuttons;
  	rdesc[31] = MOUSE_BUTTONS_MAX - nbuttons;
  }

  static __u8 *elecom_report_fixup(struct hid_device *hdev, __u8 *rdesc,
  		unsigned int *rsize)

  {

  	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
  ");
  			rdesc[47] = 0x00;
  		}
  		break;

  	case USB_DEVICE_ID_ELECOM_M_XT3URBK:
  	case USB_DEVICE_ID_ELECOM_M_XT3DRBK:

  	case USB_DEVICE_ID_ELECOM_M_XT4DRBK:

  		mouse_button_fixup(hdev, rdesc, *rsize, 6);
  		break;

  	case USB_DEVICE_ID_ELECOM_M_DT1URBK:
  	case USB_DEVICE_ID_ELECOM_M_DT1DRBK:
  	case USB_DEVICE_ID_ELECOM_M_HT1URBK:
  	case USB_DEVICE_ID_ELECOM_M_HT1DRBK:

  		mouse_button_fixup(hdev, rdesc, *rsize, 8);

  		break;

  	}

  	return rdesc;

  }
  
  static const struct hid_device_id elecom_devices[] = {

  	{ HID_BLUETOOTH_DEVICE(USB_VENDOR_ID_ELECOM, USB_DEVICE_ID_ELECOM_BM084) },

  	{ HID_USB_DEVICE(USB_VENDOR_ID_ELECOM, USB_DEVICE_ID_ELECOM_M_XT3URBK) },
  	{ HID_USB_DEVICE(USB_VENDOR_ID_ELECOM, USB_DEVICE_ID_ELECOM_M_XT3DRBK) },

  	{ HID_USB_DEVICE(USB_VENDOR_ID_ELECOM, USB_DEVICE_ID_ELECOM_M_XT4DRBK) },

  	{ HID_USB_DEVICE(USB_VENDOR_ID_ELECOM, USB_DEVICE_ID_ELECOM_M_DT1URBK) },
  	{ HID_USB_DEVICE(USB_VENDOR_ID_ELECOM, USB_DEVICE_ID_ELECOM_M_DT1DRBK) },
  	{ HID_USB_DEVICE(USB_VENDOR_ID_ELECOM, USB_DEVICE_ID_ELECOM_M_HT1URBK) },
  	{ HID_USB_DEVICE(USB_VENDOR_ID_ELECOM, USB_DEVICE_ID_ELECOM_M_HT1DRBK) },

  	{ }
  };
  MODULE_DEVICE_TABLE(hid, elecom_devices);
  
  static struct hid_driver elecom_driver = {
  	.name = "elecom",
  	.id_table = elecom_devices,
  	.report_fixup = elecom_report_fixup
  };

  module_hid_driver(elecom_driver);

  MODULE_LICENSE("GPL");