1// SPDX-License-Identifier: GPL-2.0
2/*
3 * USB Debug cable driver
4 *
5 * Copyright (C) 2006 Greg Kroah-Hartman <greg@kroah.com>
6 */
7
8#include <linux/gfp.h>
9#include <linux/kernel.h>
10#include <linux/tty.h>
11#include <linux/module.h>
12#include <linux/usb.h>
13#include <linux/usb/serial.h>
14
15#define USB_DEBUG_MAX_PACKET_SIZE 8
16#define USB_DEBUG_BRK_SIZE 8
17static const char USB_DEBUG_BRK[USB_DEBUG_BRK_SIZE] = {
18 0x00,
19 0xff,
20 0x01,
21 0xfe,
22 0x00,
23 0xfe,
24 0x01,
25 0xff,
26};
27
28static const struct usb_device_id id_table[] = {
29 { USB_DEVICE(0x0525, 0x127a) },
30 { },
31};
32
33static const struct usb_device_id dbc_id_table[] = {
34 { USB_DEVICE(0x1d6b, 0x0010) },
35 { USB_DEVICE(0x1d6b, 0x0011) },
36 { },
37};
38
39static const struct usb_device_id id_table_combined[] = {
40 { USB_DEVICE(0x0525, 0x127a) },
41 { USB_DEVICE(0x1d6b, 0x0010) },
42 { USB_DEVICE(0x1d6b, 0x0011) },
43 { },
44};
45MODULE_DEVICE_TABLE(usb, id_table_combined);
46
47/* This HW really does not support a serial break, so one will be
48 * emulated when ever the break state is set to true.
49 */
50static int usb_debug_break_ctl(struct tty_struct *tty, int break_state)
51{
52 struct usb_serial_port *port = tty->driver_data;
53 int ret;
54
55 if (!break_state)
56 return 0;
57
58 ret = usb_serial_generic_write(tty, port, buf: USB_DEBUG_BRK, USB_DEBUG_BRK_SIZE);
59 if (ret < 0)
60 return ret;
61
62 return 0;
63}
64
65static void usb_debug_process_read_urb(struct urb *urb)
66{
67 struct usb_serial_port *port = urb->context;
68
69 if (urb->actual_length == USB_DEBUG_BRK_SIZE &&
70 memcmp(p: urb->transfer_buffer, q: USB_DEBUG_BRK,
71 USB_DEBUG_BRK_SIZE) == 0) {
72 usb_serial_handle_break(port);
73 return;
74 }
75
76 usb_serial_generic_process_read_urb(urb);
77}
78
79static struct usb_serial_driver debug_device = {
80 .driver = {
81 .owner = THIS_MODULE,
82 .name = "debug",
83 },
84 .id_table = id_table,
85 .num_ports = 1,
86 .bulk_out_size = USB_DEBUG_MAX_PACKET_SIZE,
87 .break_ctl = usb_debug_break_ctl,
88 .process_read_urb = usb_debug_process_read_urb,
89};
90
91static struct usb_serial_driver dbc_device = {
92 .driver = {
93 .owner = THIS_MODULE,
94 .name = "xhci_dbc",
95 },
96 .id_table = dbc_id_table,
97 .num_ports = 1,
98 .break_ctl = usb_debug_break_ctl,
99 .process_read_urb = usb_debug_process_read_urb,
100};
101
102static struct usb_serial_driver * const serial_drivers[] = {
103 &debug_device, &dbc_device, NULL
104};
105
106module_usb_serial_driver(serial_drivers, id_table_combined);
107MODULE_LICENSE("GPL v2");
108

source code of linux/drivers/usb/serial/usb_debug.c