// SPDX-License-Identifier: GPL-2.0+
/*
 * USB Wishbone-Serial adapter driver
 *
 * Copyright (C) 2013 Wesley W. Terpstra <w.terpstra@gsi.de>
 * Copyright (C) 2013 GSI Helmholtz Centre for Heavy Ion Research GmbH
 */

#include <linux/kernel.h>
#include <linux/tty.h>
#include <linux/module.h>
#include <linux/usb.h>
#include <linux/usb/serial.h>
#include <linux/uaccess.h>

#define GSI_VENDOR_OPENCLOSE 0xB0

static const struct usb_device_id id_table[] = {
        { USB_DEVICE_AND_INTERFACE_INFO(0x1D50, 0x6062, 0xFF, 0xFF, 0xFF) },
        { },
};
MODULE_DEVICE_TABLE(usb, id_table);

/*
 * Etherbone must be told that a new stream has begun before data arrives.
 * This is necessary to restart the negotiation of Wishbone bus parameters.
 * Similarly, when the stream ends, Etherbone must be told so that the cycle
 * line can be driven low in the case that userspace failed to do so.
 */
static int usb_gsi_openclose(struct usb_serial_port *port, int value)
{
        struct usb_device *dev = port->serial->dev;

        return usb_control_msg(
                dev,
                usb_sndctrlpipe(dev, 0), /* Send to EP0OUT */
                GSI_VENDOR_OPENCLOSE,
                USB_DIR_OUT|USB_TYPE_VENDOR|USB_RECIP_INTERFACE,
                value, /* wValue = device is open(1) or closed(0) */
                port->serial->interface->cur_altsetting->desc.bInterfaceNumber,
                NULL, 0,  /* There is no data stage */
                5000); /* Timeout till operation fails */
}

static int wishbone_serial_open(struct tty_struct *tty,
                                struct usb_serial_port *port)
{
        int retval;

        retval = usb_gsi_openclose(port, 1);
        if (retval) {
                dev_err(&port->serial->dev->dev,
                       "Could not mark device as open (%d)\n",
                       retval);
                return retval;
        }

        retval = usb_serial_generic_open(tty, port);
        if (retval)
                usb_gsi_openclose(port, 0);

        return retval;
}

static void wishbone_serial_close(struct usb_serial_port *port)
{
        usb_serial_generic_close(port);
        usb_gsi_openclose(port, 0);
}

static struct usb_serial_driver wishbone_serial_device = {
        .driver = {
                .name =         "wishbone_serial",
        },
        .id_table =             id_table,
        .num_ports =            1,
        .open =                 &wishbone_serial_open,
        .close =                &wishbone_serial_close,
};

static struct usb_serial_driver * const serial_drivers[] = {
        &wishbone_serial_device, NULL
};

module_usb_serial_driver(serial_drivers, id_table);

MODULE_AUTHOR("Wesley W. Terpstra <w.terpstra@gsi.de>");
MODULE_DESCRIPTION("USB Wishbone-Serial adapter");
MODULE_LICENSE("GPL");