// SPDX-License-Identifier: GPL-2.0
/*
 * Driver for Phoenix RC Flight Controller Adapter
 *
 * Copyright (C) 2018 Marcus Folkesson <marcus.folkesson@gmail.com>
 */

#include <linux/cleanup.h>
#include <linux/errno.h>
#include <linux/input.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/slab.h>
#include <linux/uaccess.h>

#include <linux/usb.h>
#include <linux/usb/input.h>

#define PXRC_VENDOR_ID          0x1781
#define PXRC_PRODUCT_ID         0x0898

struct pxrc {
        struct input_dev        *input;
        struct usb_interface    *intf;
        struct urb              *urb;
        struct mutex            pm_mutex;
        bool                    is_open;
        char                    phys[64];
};

static void pxrc_usb_irq(struct urb *urb)
{
        struct pxrc *pxrc = urb->context;
        u8 *data = urb->transfer_buffer;
        int error;

        switch (urb->status) {
        case 0:
                /* success */
                break;
        case -ETIME:
                /* this urb is timing out */
                dev_dbg(&pxrc->intf->dev,
                        "%s - urb timed out - was the device unplugged?\n",
                        __func__);
                return;
        case -ECONNRESET:
        case -ENOENT:
        case -ESHUTDOWN:
        case -EPIPE:
                /* this urb is terminated, clean up */
                dev_dbg(&pxrc->intf->dev, "%s - urb shutting down with status: %d\n",
                        __func__, urb->status);
                return;
        default:
                dev_dbg(&pxrc->intf->dev, "%s - nonzero urb status received: %d\n",
                        __func__, urb->status);
                goto exit;
        }

        if (urb->actual_length == 8) {
                input_report_abs(pxrc->input, ABS_X, data[0]);
                input_report_abs(pxrc->input, ABS_Y, data[2]);
                input_report_abs(pxrc->input, ABS_RX, data[3]);
                input_report_abs(pxrc->input, ABS_RY, data[4]);
                input_report_abs(pxrc->input, ABS_RUDDER, data[5]);
                input_report_abs(pxrc->input, ABS_THROTTLE, data[6]);
                input_report_abs(pxrc->input, ABS_MISC, data[7]);

                input_report_key(pxrc->input, BTN_A, data[1]);
        }

exit:
        /* Resubmit to fetch new fresh URBs */
        error = usb_submit_urb(urb, GFP_ATOMIC);
        if (error && error != -EPERM)
                dev_err(&pxrc->intf->dev,
                        "%s - usb_submit_urb failed with result: %d",
                        __func__, error);
}

static int pxrc_open(struct input_dev *input)
{
        struct pxrc *pxrc = input_get_drvdata(input);
        int error;

        guard(mutex)(&pxrc->pm_mutex);
        error = usb_submit_urb(pxrc->urb, GFP_KERNEL);
        if (error) {
                dev_err(&pxrc->intf->dev,
                        "%s - usb_submit_urb failed, error: %d\n",
                        __func__, error);
                return -EIO;
        }

        pxrc->is_open = true;
        return 0;
}

static void pxrc_close(struct input_dev *input)
{
        struct pxrc *pxrc = input_get_drvdata(input);

        guard(mutex)(&pxrc->pm_mutex);
        usb_kill_urb(pxrc->urb);
        pxrc->is_open = false;
}

static void pxrc_free_urb(void *_pxrc)
{
        struct pxrc *pxrc = _pxrc;

        usb_free_urb(pxrc->urb);
}

static int pxrc_probe(struct usb_interface *intf,
                      const struct usb_device_id *id)
{
        struct usb_device *udev = interface_to_usbdev(intf);
        struct pxrc *pxrc;
        struct usb_endpoint_descriptor *epirq;
        size_t xfer_size;
        void *xfer_buf;
        int error;

        /*
         * Locate the endpoint information. This device only has an
         * interrupt endpoint.
         */
        error = usb_find_common_endpoints(intf->cur_altsetting,
                                          NULL, NULL, &epirq, NULL);
        if (error) {
                dev_err(&intf->dev, "Could not find endpoint\n");
                return error;
        }

        pxrc = devm_kzalloc(&intf->dev, sizeof(*pxrc), GFP_KERNEL);
        if (!pxrc)
                return -ENOMEM;

        mutex_init(&pxrc->pm_mutex);
        pxrc->intf = intf;

        usb_set_intfdata(pxrc->intf, pxrc);

        xfer_size = usb_endpoint_maxp(epirq);
        xfer_buf = devm_kmalloc(&intf->dev, xfer_size, GFP_KERNEL);
        if (!xfer_buf)
                return -ENOMEM;

        pxrc->urb = usb_alloc_urb(0, GFP_KERNEL);
        if (!pxrc->urb)
                return -ENOMEM;

        error = devm_add_action_or_reset(&intf->dev, pxrc_free_urb, pxrc);
        if (error)
                return error;

        usb_fill_int_urb(pxrc->urb, udev,
                         usb_rcvintpipe(udev, epirq->bEndpointAddress),
                         xfer_buf, xfer_size, pxrc_usb_irq, pxrc, 1);

        pxrc->input = devm_input_allocate_device(&intf->dev);
        if (!pxrc->input) {
                dev_err(&intf->dev, "couldn't allocate input device\n");
                return -ENOMEM;
        }

        pxrc->input->name = "PXRC Flight Controller Adapter";

        usb_make_path(udev, pxrc->phys, sizeof(pxrc->phys));
        strlcat(pxrc->phys, "/input0", sizeof(pxrc->phys));
        pxrc->input->phys = pxrc->phys;

        usb_to_input_id(udev, &pxrc->input->id);

        pxrc->input->open = pxrc_open;
        pxrc->input->close = pxrc_close;

        input_set_capability(pxrc->input, EV_KEY, BTN_A);
        input_set_abs_params(pxrc->input, ABS_X, 0, 255, 0, 0);
        input_set_abs_params(pxrc->input, ABS_Y, 0, 255, 0, 0);
        input_set_abs_params(pxrc->input, ABS_RX, 0, 255, 0, 0);
        input_set_abs_params(pxrc->input, ABS_RY, 0, 255, 0, 0);
        input_set_abs_params(pxrc->input, ABS_RUDDER, 0, 255, 0, 0);
        input_set_abs_params(pxrc->input, ABS_THROTTLE, 0, 255, 0, 0);
        input_set_abs_params(pxrc->input, ABS_MISC, 0, 255, 0, 0);

        input_set_drvdata(pxrc->input, pxrc);

        error = input_register_device(pxrc->input);
        if (error)
                return error;

        return 0;
}

static void pxrc_disconnect(struct usb_interface *intf)
{
        /* All driver resources are devm-managed. */
}

static int pxrc_suspend(struct usb_interface *intf, pm_message_t message)
{
        struct pxrc *pxrc = usb_get_intfdata(intf);

        guard(mutex)(&pxrc->pm_mutex);
        if (pxrc->is_open)
                usb_kill_urb(pxrc->urb);

        return 0;
}

static int pxrc_resume(struct usb_interface *intf)
{
        struct pxrc *pxrc = usb_get_intfdata(intf);

        guard(mutex)(&pxrc->pm_mutex);
        if (pxrc->is_open && usb_submit_urb(pxrc->urb, GFP_KERNEL) < 0)
                return -EIO;

        return 0;
}

static int pxrc_pre_reset(struct usb_interface *intf)
{
        struct pxrc *pxrc = usb_get_intfdata(intf);

        mutex_lock(&pxrc->pm_mutex);
        usb_kill_urb(pxrc->urb);
        return 0;
}

static int pxrc_post_reset(struct usb_interface *intf)
{
        struct pxrc *pxrc = usb_get_intfdata(intf);
        int retval = 0;

        if (pxrc->is_open && usb_submit_urb(pxrc->urb, GFP_KERNEL) < 0)
                retval = -EIO;

        mutex_unlock(&pxrc->pm_mutex);

        return retval;
}

static int pxrc_reset_resume(struct usb_interface *intf)
{
        return pxrc_resume(intf);
}

static const struct usb_device_id pxrc_table[] = {
        { USB_DEVICE(PXRC_VENDOR_ID, PXRC_PRODUCT_ID) },
        { }
};
MODULE_DEVICE_TABLE(usb, pxrc_table);

static struct usb_driver pxrc_driver = {
        .name =         "pxrc",
        .probe =        pxrc_probe,
        .disconnect =   pxrc_disconnect,
        .id_table =     pxrc_table,
        .suspend        = pxrc_suspend,
        .resume         = pxrc_resume,
        .pre_reset      = pxrc_pre_reset,
        .post_reset     = pxrc_post_reset,
        .reset_resume   = pxrc_reset_resume,
};

module_usb_driver(pxrc_driver);

MODULE_AUTHOR("Marcus Folkesson <marcus.folkesson@gmail.com>");
MODULE_DESCRIPTION("PhoenixRC Flight Controller Adapter");
MODULE_LICENSE("GPL v2");