LXR linux/drivers/usb/serial/aircable.c

   1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 * AIRcable USB Bluetooth Dongle Driver.
   4 *
   5 * Copyright (C) 2010 Johan Hovold <jhovold@gmail.com>
   6 * Copyright (C) 2006 Manuel Francisco Naranjo (naranjo.manuel@gmail.com)
   7 *
   8 * The device works as an standard CDC device, it has 2 interfaces, the first
   9 * one is for firmware access and the second is the serial one.
  10 * The protocol is very simply, there are two possibilities reading or writing.
  11 * When writing the first urb must have a Header that starts with 0x20 0x29 the
  12 * next two bytes must say how much data will be sent.
  13 * When reading the process is almost equal except that the header starts with
  14 * 0x00 0x20.
  15 *
  16 * The device simply need some stuff to understand data coming from the usb
  17 * buffer: The First and Second byte is used for a Header, the Third and Fourth
  18 * tells the  device the amount of information the package holds.
  19 * Packages are 60 bytes long Header Stuff.
  20 * When writing to the device the first two bytes of the header are 0x20 0x29
  21 * When reading the bytes are 0x00 0x20, or 0x00 0x10, there is an strange
  22 * situation, when too much data arrives to the device because it sends the data
  23 * but with out the header. I will use a simply hack to override this situation,
  24 * if there is data coming that does not contain any header, then that is data
  25 * that must go directly to the tty, as there is no documentation about if there
  26 * is any other control code, I will simply check for the first
  27 * one.
  28 *
  29 * I have taken some info from a Greg Kroah-Hartman article:
  30 * http://www.linuxjournal.com/article/6573
  31 * And from Linux Device Driver Kit CD, which is a great work, the authors taken
  32 * the work to recompile lots of information an knowledge in drivers development
  33 * and made it all available inside a cd.
  34 * URL: http://kernel.org/pub/linux/kernel/people/gregkh/ddk/
  35 *
  36 */
  37
  38#include <asm/unaligned.h>
  39#include <linux/tty.h>
  40#include <linux/slab.h>
  41#include <linux/module.h>
  42#include <linux/tty_flip.h>
  43#include <linux/usb.h>
  44#include <linux/usb/serial.h>
  45
  46/* Vendor and Product ID */
  47#define AIRCABLE_VID            0x16CA
  48#define AIRCABLE_USB_PID        0x1502
  49
  50/* Protocol Stuff */
  51#define HCI_HEADER_LENGTH       0x4
  52#define TX_HEADER_0             0x20
  53#define TX_HEADER_1             0x29
  54#define RX_HEADER_0             0x00
  55#define RX_HEADER_1             0x20
  56#define HCI_COMPLETE_FRAME      64
  57
  58/* rx_flags */
  59#define THROTTLED               0x01
  60#define ACTUALLY_THROTTLED      0x02
  61
  62#define DRIVER_AUTHOR "Naranjo, Manuel Francisco <naranjo.manuel@gmail.com>, Johan Hovold <jhovold@gmail.com>"
  63#define DRIVER_DESC "AIRcable USB Driver"
  64
  65/* ID table that will be registered with USB core */
  66static const struct usb_device_id id_table[] = {
  67        { USB_DEVICE(AIRCABLE_VID, AIRCABLE_USB_PID) },
  68        { },
  69};
  70MODULE_DEVICE_TABLE(usb, id_table);
  71
  72static int aircable_prepare_write_buffer(struct usb_serial_port *port,
  73                                                void *dest, size_t size)
  74{
  75        int count;
  76        unsigned char *buf = dest;
  77
  78        count = kfifo_out_locked(&port->write_fifo, buf + HCI_HEADER_LENGTH,
  79                                        size - HCI_HEADER_LENGTH, &port->lock);
  80        buf[0] = TX_HEADER_0;
  81        buf[1] = TX_HEADER_1;
  82        put_unaligned_le16(count, &buf[2]);
  83
  84        return count + HCI_HEADER_LENGTH;
  85}
  86
  87static int aircable_calc_num_ports(struct usb_serial *serial,
  88                                        struct usb_serial_endpoints *epds)
  89{
  90        /* Ignore the first interface, which has no bulk endpoints. */
  91        if (epds->num_bulk_out == 0) {
  92                dev_dbg(&serial->interface->dev,
  93                        "ignoring interface with no bulk-out endpoints\n");
  94                return -ENODEV;
  95        }
  96
  97        return 1;
  98}
  99
 100static int aircable_process_packet(struct usb_serial_port *port,
 101                int has_headers, char *packet, int len)
 102{
 103        if (has_headers) {
 104                len -= HCI_HEADER_LENGTH;
 105                packet += HCI_HEADER_LENGTH;
 106        }
 107        if (len <= 0) {
 108                dev_dbg(&port->dev, "%s - malformed packet\n", __func__);
 109                return 0;
 110        }
 111
 112        tty_insert_flip_string(&port->port, packet, len);
 113
 114        return len;
 115}
 116
 117static void aircable_process_read_urb(struct urb *urb)
 118{
 119        struct usb_serial_port *port = urb->context;
 120        char *data = (char *)urb->transfer_buffer;
 121        int has_headers;
 122        int count;
 123        int len;
 124        int i;
 125
 126        has_headers = (urb->actual_length > 2 && data[0] == RX_HEADER_0);
 127
 128        count = 0;
 129        for (i = 0; i < urb->actual_length; i += HCI_COMPLETE_FRAME) {
 130                len = min_t(int, urb->actual_length - i, HCI_COMPLETE_FRAME);
 131                count += aircable_process_packet(port, has_headers,
 132                                                                &data[i], len);
 133        }
 134
 135        if (count)
 136                tty_flip_buffer_push(&port->port);
 137}
 138
 139static struct usb_serial_driver aircable_device = {
 140        .driver = {
 141                .owner =        THIS_MODULE,
 142                .name =         "aircable",
 143        },
 144        .id_table =             id_table,
 145        .bulk_out_size =        HCI_COMPLETE_FRAME,
 146        .calc_num_ports =       aircable_calc_num_ports,
 147        .process_read_urb =     aircable_process_read_urb,
 148        .prepare_write_buffer = aircable_prepare_write_buffer,
 149        .throttle =             usb_serial_generic_throttle,
 150        .unthrottle =           usb_serial_generic_unthrottle,
 151};
 152
 153static struct usb_serial_driver * const serial_drivers[] = {
 154        &aircable_device, NULL
 155};
 156
 157module_usb_serial_driver(serial_drivers, id_table);
 158
 159MODULE_AUTHOR(DRIVER_AUTHOR);
 160MODULE_DESCRIPTION(DRIVER_DESC);
 161MODULE_LICENSE("GPL v2");
 162