drivers/usb/serial/aircable.c

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