// SPDX-License-Identifier: GPL-2.0
/*
 * USB Debug cable driver
 *
 * Copyright (C) 2006 Greg Kroah-Hartman <greg@kroah.com>
 */

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

#define USB_DEBUG_MAX_PACKET_SIZE       8
#define USB_DEBUG_BRK_SIZE              8
static const char USB_DEBUG_BRK[USB_DEBUG_BRK_SIZE] = {
        0x00,
        0xff,
        0x01,
        0xfe,
        0x00,
        0xfe,
        0x01,
        0xff,
};

static const struct usb_device_id id_table[] = {
        { USB_DEVICE(0x0525, 0x127a) },
        { },
};

static const struct usb_device_id dbc_id_table[] = {
        { USB_DEVICE(0x1d6b, 0x0010) },
        { USB_DEVICE(0x1d6b, 0x0011) },
        { },
};

static const struct usb_device_id id_table_combined[] = {
        { USB_DEVICE(0x0525, 0x127a) },
        { USB_DEVICE(0x1d6b, 0x0010) },
        { USB_DEVICE(0x1d6b, 0x0011) },
        { },
};
MODULE_DEVICE_TABLE(usb, id_table_combined);

/* This HW really does not support a serial break, so one will be
 * emulated when ever the break state is set to true.
 */
static int usb_debug_break_ctl(struct tty_struct *tty, int break_state)
{
        struct usb_serial_port *port = tty->driver_data;
        int ret;

        if (!break_state)
                return 0;

        ret = usb_serial_generic_write(tty, port, USB_DEBUG_BRK, USB_DEBUG_BRK_SIZE);
        if (ret < 0)
                return ret;

        return 0;
}

static void usb_debug_process_read_urb(struct urb *urb)
{
        struct usb_serial_port *port = urb->context;

        if (urb->actual_length == USB_DEBUG_BRK_SIZE &&
                memcmp(urb->transfer_buffer, USB_DEBUG_BRK,
                                                USB_DEBUG_BRK_SIZE) == 0) {
                usb_serial_handle_break(port);
                return;
        }

        usb_serial_generic_process_read_urb(urb);
}

static void usb_debug_init_termios(struct tty_struct *tty)
{
        tty->termios.c_lflag &= ~(ECHO | ECHONL);
}

static struct usb_serial_driver debug_device = {
        .driver = {
                .name =         "debug",
        },
        .id_table =             id_table,
        .num_ports =            1,
        .bulk_out_size =        USB_DEBUG_MAX_PACKET_SIZE,
        .break_ctl =            usb_debug_break_ctl,
        .init_termios =         usb_debug_init_termios,
        .process_read_urb =     usb_debug_process_read_urb,
};

static struct usb_serial_driver dbc_device = {
        .driver = {
                .name =         "xhci_dbc",
        },
        .id_table =             dbc_id_table,
        .num_ports =            1,
        .break_ctl =            usb_debug_break_ctl,
        .init_termios =         usb_debug_init_termios,
        .process_read_urb =     usb_debug_process_read_urb,
};

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

module_usb_serial_driver(serial_drivers, id_table_combined);
MODULE_DESCRIPTION("USB Debug cable driver");
MODULE_LICENSE("GPL v2");