// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *  HID driver for Gembird Joypad, "PC Game Controller"
 *
 *  Copyright (c) 2015 Red Hat, Inc
 *  Copyright (c) 2015 Benjamin Tissoires
 */

/*
 */

#include <linux/device.h>
#include <linux/hid.h>
#include <linux/module.h>

#include "hid-ids.h"

#define GEMBIRD_START_FAULTY_RDESC      8

static const __u8 gembird_jpd_faulty_rdesc[] = {
        0x75, 0x08,                     /*   Report Size (8)            */
        0x95, 0x05,                     /*   Report Count (5)           */
        0x15, 0x00,                     /*   Logical Minimum (0)        */
        0x26, 0xff, 0x00,               /*   Logical Maximum (255)      */
        0x35, 0x00,                     /*   Physical Minimum (0)       */
        0x46, 0xff, 0x00,               /*   Physical Maximum (255)     */
        0x09, 0x30,                     /*   Usage (X)                  */
        0x09, 0x31,                     /*   Usage (Y)                  */
        0x09, 0x32,                     /*   Usage (Z)                  */
        0x09, 0x32,                     /*   Usage (Z)                  */
        0x09, 0x35,                     /*   Usage (Rz)                 */
        0x81, 0x02,                     /*   Input (Data,Var,Abs)       */
};

/*
 * we fix the report descriptor by:
 * - marking the first Z axis as constant (so it is ignored by HID)
 * - assign the original second Z to Rx
 * - assign the original Rz to Ry
 */
static const __u8 gembird_jpd_fixed_rdesc[] = {
        0x75, 0x08,                     /*   Report Size (8)            */
        0x95, 0x02,                     /*   Report Count (2)           */
        0x15, 0x00,                     /*   Logical Minimum (0)        */
        0x26, 0xff, 0x00,               /*   Logical Maximum (255)      */
        0x35, 0x00,                     /*   Physical Minimum (0)       */
        0x46, 0xff, 0x00,               /*   Physical Maximum (255)     */
        0x09, 0x30,                     /*   Usage (X)                  */
        0x09, 0x31,                     /*   Usage (Y)                  */
        0x81, 0x02,                     /*   Input (Data,Var,Abs)       */
        0x95, 0x01,                     /*   Report Count (1)           */
        0x09, 0x32,                     /*   Usage (Z)                  */
        0x81, 0x01,                     /*   Input (Cnst,Arr,Abs)       */
        0x95, 0x02,                     /*   Report Count (2)           */
        0x09, 0x33,                     /*   Usage (Rx)                 */
        0x09, 0x34,                     /*   Usage (Ry)                 */
        0x81, 0x02,                     /*   Input (Data,Var,Abs)       */
};

static const __u8 *gembird_report_fixup(struct hid_device *hdev, __u8 *rdesc,
                unsigned int *rsize)
{
        __u8 *new_rdesc;
        /* delta_size is > 0 */
        size_t delta_size = sizeof(gembird_jpd_fixed_rdesc) -
                            sizeof(gembird_jpd_faulty_rdesc);
        size_t new_size = *rsize + delta_size;

        if (*rsize >= 31 && !memcmp(&rdesc[GEMBIRD_START_FAULTY_RDESC],
                                    gembird_jpd_faulty_rdesc,
                                    sizeof(gembird_jpd_faulty_rdesc))) {
                new_rdesc = devm_kzalloc(&hdev->dev, new_size, GFP_KERNEL);
                if (new_rdesc == NULL)
                        return rdesc;

                dev_info(&hdev->dev,
                         "fixing Gembird JPD-DualForce 2 report descriptor.\n");

                /* start by copying the end of the rdesc */
                memcpy(new_rdesc + delta_size, rdesc, *rsize);

                /* add the correct beginning */
                memcpy(new_rdesc, rdesc, GEMBIRD_START_FAULTY_RDESC);

                /* replace the faulty part with the fixed one */
                memcpy(new_rdesc + GEMBIRD_START_FAULTY_RDESC,
                       gembird_jpd_fixed_rdesc,
                       sizeof(gembird_jpd_fixed_rdesc));

                *rsize = new_size;
                rdesc = new_rdesc;
        }

        return rdesc;
}

static const struct hid_device_id gembird_devices[] = {
        { HID_USB_DEVICE(USB_VENDOR_ID_GEMBIRD,
                         USB_DEVICE_ID_GEMBIRD_JPD_DUALFORCE2) },
        { }
};
MODULE_DEVICE_TABLE(hid, gembird_devices);

static struct hid_driver gembird_driver = {
        .name = "gembird",
        .id_table = gembird_devices,
        .report_fixup = gembird_report_fixup,
};
module_hid_driver(gembird_driver);

MODULE_AUTHOR("Benjamin Tissoires <benjamin.tissoires@gmail.com>");
MODULE_DESCRIPTION("HID Gembird joypad driver");
MODULE_LICENSE("GPL");