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 posibilities 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 sended.
  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  * The driver registers himself with the USB-serial core and the USB Core. I had
  33  * to implement a probe function against USB-serial, because other way, the
  34  * driver was attaching himself to both interfaces. I have tryed with different
  35  * configurations of usb_serial_driver with out exit, only the probe function
  36  * could handle this correctly.
  37  *
  38  * I have taken some info from a Greg Kroah-Hartman article:
  39  * http://www.linuxjournal.com/article/6573
  40  * And from Linux Device Driver Kit CD, which is a great work, the authors taken
  41  * the work to recompile lots of information an knowladge in drivers development
  42  * and made it all avaible inside a cd.
  43  * URL: http://kernel.org/pub/linux/kernel/people/gregkh/ddk/
  44  *
  45  */
  46
  47 #include <asm/unaligned.h>
  48 #include <linux/tty.h>
  49 #include <linux/slab.h>
  50 #include <linux/module.h>
  51 #include <linux/tty_flip.h>
  52 #include <linux/usb.h>
  53 #include <linux/usb/serial.h>
  54
  55 static bool debug;
  56
  57 /* Vendor and Product ID */
  58 #define AIRCABLE_VID            0x16CA
  59 #define AIRCABLE_USB_PID        0x1502
  60
  61 /* Protocol Stuff */
  62 #define HCI_HEADER_LENGTH       0x4
  63 #define TX_HEADER_0             0x20
  64 #define TX_HEADER_1             0x29
  65 #define RX_HEADER_0             0x00
  66 #define RX_HEADER_1             0x20
  67 #define HCI_COMPLETE_FRAME      64
  68
  69 /* rx_flags */
  70 #define THROTTLED               0x01
  71 #define ACTUALLY_THROTTLED      0x02
  72
  73 /*
  74  * Version Information
  75  */
  76 #define DRIVER_VERSION "v2.0"
  77 #define DRIVER_AUTHOR "Naranjo, Manuel Francisco <naranjo.manuel@gmail.com>, Johan Hovold <jhovold@gmail.com>"
  78 #define DRIVER_DESC "AIRcable USB Driver"
  79
  80 /* ID table that will be registered with USB core */
  81 static const struct usb_device_id id_table[] = {
  82         { USB_DEVICE(AIRCABLE_VID, AIRCABLE_USB_PID) },
  83         { },
  84 };
  85 MODULE_DEVICE_TABLE(usb, id_table);
  86
  87 static int aircable_prepare_write_buffer(struct usb_serial_port *port,
  88                                                 void *dest, size_t size)
  89 {
  90         int count;
  91         unsigned char *buf = dest;
  92
  93         count = kfifo_out_locked(&port->write_fifo, buf + HCI_HEADER_LENGTH,
  94                                         size - HCI_HEADER_LENGTH, &port->lock);
  95         buf[0] = TX_HEADER_0;
  96         buf[1] = TX_HEADER_1;
  97         put_unaligned_le16(count, &buf[2]);
  98
  99         return count + HCI_HEADER_LENGTH;
 100 }
 101
 102 static int aircable_probe(struct usb_serial *serial,
 103                           const struct usb_device_id *id)
 104 {
 105         struct usb_host_interface *iface_desc = serial->interface->
 106                                                                 cur_altsetting;
 107         struct usb_endpoint_descriptor *endpoint;
 108         int num_bulk_out = 0;
 109         int i;
 110
 111         for (i = 0; i < iface_desc->desc.bNumEndpoints; i++) {
 112                 endpoint = &iface_desc->endpoint[i].desc;
 113                 if (usb_endpoint_is_bulk_out(endpoint)) {
 114                         dev_dbg(&serial->dev->dev,
 115                                 "found bulk out on endpoint %d\n", i);
 116                         ++num_bulk_out;
 117                 }
 118         }
 119
 120         if (num_bulk_out == 0) {
 121                 dev_dbg(&serial->dev->dev, "Invalid interface, discarding\n");
 122                 return -ENODEV;
 123         }
 124
 125         return 0;
 126 }
 127
 128 static int aircable_process_packet(struct tty_struct *tty,
 129                         struct usb_serial_port *port, int has_headers,
 130                         char *packet, int len)
 131 {
 132         if (has_headers) {
 133                 len -= HCI_HEADER_LENGTH;
 134                 packet += HCI_HEADER_LENGTH;
 135         }
 136         if (len <= 0) {
 137                 dev_dbg(&port->dev, "%s - malformed packet\n", __func__);
 138                 return 0;
 139         }
 140
 141         tty_insert_flip_string(tty, packet, len);
 142
 143         return len;
 144 }
 145
 146 static void aircable_process_read_urb(struct urb *urb)
 147 {
 148         struct usb_serial_port *port = urb->context;
 149         char *data = (char *)urb->transfer_buffer;
 150         struct tty_struct *tty;
 151         int has_headers;
 152         int count;
 153         int len;
 154         int i;
 155
 156         tty = tty_port_tty_get(&port->port);
 157         if (!tty)
 158                 return;
 159
 160         has_headers = (urb->actual_length > 2 && data[0] == RX_HEADER_0);
 161
 162         count = 0;
 163         for (i = 0; i < urb->actual_length; i += HCI_COMPLETE_FRAME) {
 164                 len = min_t(int, urb->actual_length - i, HCI_COMPLETE_FRAME);
 165                 count += aircable_process_packet(tty, port, has_headers,
 166                                                                 &data[i], len);
 167         }
 168
 169         if (count)
 170                 tty_flip_buffer_push(tty);
 171         tty_kref_put(tty);
 172 }
 173
 174 static struct usb_serial_driver aircable_device = {
 175         .driver = {
 176                 .owner =        THIS_MODULE,
 177                 .name =         "aircable",
 178         },
 179         .id_table =             id_table,
 180         .num_ports =            1,
 181         .bulk_out_size =        HCI_COMPLETE_FRAME,
 182         .probe =                aircable_probe,
 183         .process_read_urb =     aircable_process_read_urb,
 184         .prepare_write_buffer = aircable_prepare_write_buffer,
 185         .throttle =             usb_serial_generic_throttle,
 186         .unthrottle =           usb_serial_generic_unthrottle,
 187 };
 188
 189 static struct usb_serial_driver * const serial_drivers[] = {
 190         &aircable_device, NULL
 191 };
 192
 193 module_usb_serial_driver(serial_drivers, id_table);
 194
 195 MODULE_AUTHOR(DRIVER_AUTHOR);
 196 MODULE_DESCRIPTION(DRIVER_DESC);
 197 MODULE_VERSION(DRIVER_VERSION);
 198 MODULE_LICENSE("GPL");
 199
 200 module_param(debug, bool, S_IRUGO | S_IWUSR);
 201 MODULE_PARM_DESC(debug, "Debug enabled or not");