// SPDX-License-Identifier: GPL-2.0
/*
 * When connected to the machine, the Thrustmaster wheels appear as
 * a «generic» hid gamepad called "Thrustmaster FFB Wheel".
 *
 * When in this mode not every functionality of the wheel, like the force feedback,
 * are available. To enable all functionalities of a Thrustmaster wheel we have to send
 * to it a specific USB CONTROL request with a code different for each wheel.
 *
 * This driver tries to understand which model of Thrustmaster wheel the generic
 * "Thrustmaster FFB Wheel" really is and then sends the appropriate control code.
 *
 * Copyright (c) 2020-2021 Dario Pagani <dario.pagani.146+linuxk@gmail.com>
 * Copyright (c) 2020-2021 Kim Kuparinen <kimi.h.kuparinen@gmail.com>
 */
#include <linux/hid.h>
#include <linux/usb.h>
#include <linux/input.h>
#include <linux/slab.h>
#include <linux/module.h>

/*
 * These interrupts are used to prevent a nasty crash when initializing the
 * T300RS. Used in thrustmaster_interrupts().
 */
static const u8 setup_0[] = { 0x42, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 };
static const u8 setup_1[] = { 0x0a, 0x04, 0x90, 0x03, 0x00, 0x00, 0x00, 0x00 };
static const u8 setup_2[] = { 0x0a, 0x04, 0x00, 0x0c, 0x00, 0x00, 0x00, 0x00 };
static const u8 setup_3[] = { 0x0a, 0x04, 0x12, 0x10, 0x00, 0x00, 0x00, 0x00 };
static const u8 setup_4[] = { 0x0a, 0x04, 0x00, 0x06, 0x00, 0x00, 0x00, 0x00 };
static const u8 *const setup_arr[] = { setup_0, setup_1, setup_2, setup_3, setup_4 };
static const unsigned int setup_arr_sizes[] = {
        ARRAY_SIZE(setup_0),
        ARRAY_SIZE(setup_1),
        ARRAY_SIZE(setup_2),
        ARRAY_SIZE(setup_3),
        ARRAY_SIZE(setup_4)
};
/*
 * This struct contains for each type of
 * Thrustmaster wheel
 *
 * Note: The values are stored in the CPU
 * endianness, the USB protocols always use
 * little endian; the macro cpu_to_le[BIT]()
 * must be used when preparing USB packets
 * and vice-versa
 */
struct tm_wheel_info {
        uint16_t wheel_type;

        /*
         * See when the USB control out packet is prepared...
         * @TODO The TMX seems to require multiple control codes to switch.
         */
        uint16_t switch_value;

        char const *const wheel_name;
};

/*
 * Known wheels.
 * Note: TMX does not work as it requires 2 control packets
 */
static const struct tm_wheel_info tm_wheels_infos[] = {
        {0x0306, 0x0006, "Thrustmaster T150RS"},
        {0x0206, 0x0005, "Thrustmaster T300RS"},
        {0x0204, 0x0005, "Thrustmaster T300 Ferrari Alcantara Edition"},
        {0x0002, 0x0002, "Thrustmaster T500RS"}
        //{0x0407, 0x0001, "Thrustmaster TMX"}
};

static const uint8_t tm_wheels_infos_length = 4;

/*
 * This structs contains (in little endian) the response data
 * of the wheel to the request 73
 *
 * A sufficient research to understand what each field does is not
 * beign conducted yet. The position and meaning of fields are a
 * just a very optimistic guess based on instinct....
 */
struct __packed tm_wheel_response
{
        /*
         * Seems to be the type of packet
         * - 0x0049 if is data.a (15 bytes)
         * - 0x0047 if is data.b (7 bytes)
         */
        uint16_t type;

        union {
                struct __packed {
                        uint16_t field0;
                        uint16_t field1;
                        /*
                         * Seems to be the model code of the wheel
                         * Read table thrustmaster_wheels to values
                         */
                        uint16_t model;

                        uint16_t field2;
                        uint16_t field3;
                        uint16_t field4;
                        uint16_t field5;
                } a;
                struct __packed {
                        uint16_t field0;
                        uint16_t field1;
                        uint16_t model;
                } b;
        } data;
};

struct tm_wheel {
        struct usb_device *usb_dev;
        struct urb *urb;

        struct usb_ctrlrequest *model_request;
        struct tm_wheel_response *response;

        struct usb_ctrlrequest *change_request;
};

/* The control packet to send to wheel */
static const struct usb_ctrlrequest model_request = {
        .bRequestType = 0xc1,
        .bRequest = 73,
        .wValue = 0,
        .wIndex = 0,
        .wLength = cpu_to_le16(0x0010)
};

static const struct usb_ctrlrequest change_request = {
        .bRequestType = 0x41,
        .bRequest = 83,
        .wValue = 0, // Will be filled by the driver
        .wIndex = 0,
        .wLength = 0
};

/*
 * On some setups initializing the T300RS crashes the kernel,
 * these interrupts fix that particular issue. So far they haven't caused any
 * adverse effects in other wheels.
 */
static void thrustmaster_interrupts(struct hid_device *hdev)
{
        int ret, trans, i, b_ep;
        u8 *send_buf = kmalloc(256, GFP_KERNEL);
        struct usb_host_endpoint *ep;
        struct device *dev = &hdev->dev;
        struct usb_interface *usbif = to_usb_interface(dev->parent);
        struct usb_device *usbdev = interface_to_usbdev(usbif);

        if (!send_buf) {
                hid_err(hdev, "failed allocating send buffer\n");
                return;
        }

        ep = &usbif->cur_altsetting->endpoint[1];
        b_ep = ep->desc.bEndpointAddress;

        for (i = 0; i < ARRAY_SIZE(setup_arr); ++i) {
                memcpy(send_buf, setup_arr[i], setup_arr_sizes[i]);

                ret = usb_interrupt_msg(usbdev,
                        usb_sndintpipe(usbdev, b_ep),
                        send_buf,
                        setup_arr_sizes[i],
                        &trans,
                        USB_CTRL_SET_TIMEOUT);

                if (ret) {
                        hid_err(hdev, "setup data couldn't be sent\n");
                        kfree(send_buf);
                        return;
                }
        }

        kfree(send_buf);
}

static void thrustmaster_change_handler(struct urb *urb)
{
        struct hid_device *hdev = urb->context;

        // The wheel seems to kill himself before answering the host and therefore is violating the USB protocol...
        if (urb->status == 0 || urb->status == -EPROTO || urb->status == -EPIPE)
                hid_info(hdev, "Success?! The wheel should have been initialized!\n");
        else
                hid_warn(hdev, "URB to change wheel mode seems to have failed with error %d\n", urb->status);
}

/*
 * Called by the USB subsystem when the wheel responses to our request
 * to get [what it seems to be] the wheel's model.
 *
 * If the model id is recognized then we send an opportune USB CONTROL REQUEST
 * to switch the wheel to its full capabilities
 */
static void thrustmaster_model_handler(struct urb *urb)
{
        struct hid_device *hdev = urb->context;
        struct tm_wheel *tm_wheel = hid_get_drvdata(hdev);
        uint16_t model = 0;
        int i, ret;
        const struct tm_wheel_info *twi = 0;

        if (urb->status) {
                hid_err(hdev, "URB to get model id failed with error %d\n", urb->status);
                return;
        }

        if (tm_wheel->response->type == cpu_to_le16(0x49))
                model = le16_to_cpu(tm_wheel->response->data.a.model);
        else if (tm_wheel->response->type == cpu_to_le16(0x47))
                model = le16_to_cpu(tm_wheel->response->data.b.model);
        else {
                hid_err(hdev, "Unknown packet type 0x%x, unable to proceed further with wheel init\n", tm_wheel->response->type);
                return;
        }

        for (i = 0; i < tm_wheels_infos_length && !twi; i++)
                if (tm_wheels_infos[i].wheel_type == model)
                        twi = tm_wheels_infos + i;

        if (twi)
                hid_info(hdev, "Wheel with model id 0x%x is a %s\n", model, twi->wheel_name);
        else {
                hid_err(hdev, "Unknown wheel's model id 0x%x, unable to proceed further with wheel init\n", model);
                return;
        }

        tm_wheel->change_request->wValue = cpu_to_le16(twi->switch_value);
        usb_fill_control_urb(
                tm_wheel->urb,
                tm_wheel->usb_dev,
                usb_sndctrlpipe(tm_wheel->usb_dev, 0),
                (char *)tm_wheel->change_request,
                0, 0, // We do not expect any response from the wheel
                thrustmaster_change_handler,
                hdev
        );

        ret = usb_submit_urb(tm_wheel->urb, GFP_ATOMIC);
        if (ret)
                hid_err(hdev, "Error %d while submitting the change URB. I am unable to initialize this wheel...\n", ret);
}

static void thrustmaster_remove(struct hid_device *hdev)
{
        struct tm_wheel *tm_wheel = hid_get_drvdata(hdev);

        usb_kill_urb(tm_wheel->urb);

        kfree(tm_wheel->change_request);
        kfree(tm_wheel->response);
        kfree(tm_wheel->model_request);
        usb_free_urb(tm_wheel->urb);
        kfree(tm_wheel);

        hid_hw_stop(hdev);
}

/*
 * Function called by HID when a hid Thrustmaster FFB wheel is connected to the host.
 * This function starts the hid dev, tries to allocate the tm_wheel data structure and
 * finally send an USB CONTROL REQUEST to the wheel to get [what it seems to be] its
 * model type.
 */
static int thrustmaster_probe(struct hid_device *hdev, const struct hid_device_id *id)
{
        int ret = 0;
        struct tm_wheel *tm_wheel = 0;

        ret = hid_parse(hdev);
        if (ret) {
                hid_err(hdev, "parse failed with error %d\n", ret);
                goto error0;
        }

        ret = hid_hw_start(hdev, HID_CONNECT_DEFAULT & ~HID_CONNECT_FF);
        if (ret) {
                hid_err(hdev, "hw start failed with error %d\n", ret);
                goto error0;
        }

        // Now we allocate the tm_wheel
        tm_wheel = kzalloc(sizeof(struct tm_wheel), GFP_KERNEL);
        if (!tm_wheel) {
                ret = -ENOMEM;
                goto error1;
        }

        tm_wheel->urb = usb_alloc_urb(0, GFP_ATOMIC);
        if (!tm_wheel->urb) {
                ret = -ENOMEM;
                goto error2;
        }

        tm_wheel->model_request = kmemdup(&model_request,
                                          sizeof(struct usb_ctrlrequest),
                                          GFP_KERNEL);
        if (!tm_wheel->model_request) {
                ret = -ENOMEM;
                goto error3;
        }

        tm_wheel->response = kzalloc(sizeof(struct tm_wheel_response), GFP_KERNEL);
        if (!tm_wheel->response) {
                ret = -ENOMEM;
                goto error4;
        }

        tm_wheel->change_request = kmemdup(&change_request,
                                           sizeof(struct usb_ctrlrequest),
                                           GFP_KERNEL);
        if (!tm_wheel->change_request) {
                ret = -ENOMEM;
                goto error5;
        }

        tm_wheel->usb_dev = interface_to_usbdev(to_usb_interface(hdev->dev.parent));
        hid_set_drvdata(hdev, tm_wheel);

        thrustmaster_interrupts(hdev);

        usb_fill_control_urb(
                tm_wheel->urb,
                tm_wheel->usb_dev,
                usb_rcvctrlpipe(tm_wheel->usb_dev, 0),
                (char *)tm_wheel->model_request,
                tm_wheel->response,
                sizeof(struct tm_wheel_response),
                thrustmaster_model_handler,
                hdev
        );

        ret = usb_submit_urb(tm_wheel->urb, GFP_ATOMIC);
        if (ret) {
                hid_err(hdev, "Error %d while submitting the URB. I am unable to initialize this wheel...\n", ret);
                goto error6;
        }

        return ret;

error6: kfree(tm_wheel->change_request);
error5: kfree(tm_wheel->response);
error4: kfree(tm_wheel->model_request);
error3: usb_free_urb(tm_wheel->urb);
error2: kfree(tm_wheel);
error1: hid_hw_stop(hdev);
error0:
        return ret;
}

static const struct hid_device_id thrustmaster_devices[] = {
        { HID_USB_DEVICE(0x044f, 0xb65d)},
        {}
};

MODULE_DEVICE_TABLE(hid, thrustmaster_devices);

static struct hid_driver thrustmaster_driver = {
        .name = "hid-thrustmaster",
        .id_table = thrustmaster_devices,
        .probe = thrustmaster_probe,
        .remove = thrustmaster_remove,
};

module_hid_driver(thrustmaster_driver);

MODULE_AUTHOR("Dario Pagani <dario.pagani.146+linuxk@gmail.com>");
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Driver to initialize some steering wheel joysticks from Thrustmaster");