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  * 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 tried 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 knowledge in drivers development
  42  * and made it all available 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 /* Vendor and Product ID */
  56 #define AIRCABLE_VID            0x16CA
  57 #define AIRCABLE_USB_PID        0x1502
  58
  59 /* Protocol Stuff */
  60 #define HCI_HEADER_LENGTH       0x4
  61 #define TX_HEADER_0             0x20
  62 #define TX_HEADER_1             0x29
  63 #define RX_HEADER_0             0x00
  64 #define RX_HEADER_1             0x20
  65 #define HCI_COMPLETE_FRAME      64
  66
  67 /* rx_flags */
  68 #define THROTTLED               0x01
  69 #define ACTUALLY_THROTTLED      0x02
  70
  71 #define DRIVER_AUTHOR "Naranjo, Manuel Francisco <naranjo.manuel@gmail.com>, Johan Hovold <jhovold@gmail.com>"
  72 #define DRIVER_DESC "AIRcable USB Driver"
  73
  74 /* ID table that will be registered with USB core */
  75 static const struct usb_device_id id_table[] = {
  76         { USB_DEVICE(AIRCABLE_VID, AIRCABLE_USB_PID) },
  77         { },
  78 };
  79 MODULE_DEVICE_TABLE(usb, id_table);
  80
  81 static int aircable_prepare_write_buffer(struct usb_serial_port *port,
  82                                                 void *dest, size_t size)
  83 {
  84         int count;
  85         unsigned char *buf = dest;
  86
  87         count = kfifo_out_locked(&port->write_fifo, buf + HCI_HEADER_LENGTH,
  88                                         size - HCI_HEADER_LENGTH, &port->lock);
  89         buf[0] = TX_HEADER_0;
  90         buf[1] = TX_HEADER_1;
  91         put_unaligned_le16(count, &buf[2]);
  92
  93         return count + HCI_HEADER_LENGTH;
  94 }
  95
  96 static int aircable_probe(struct usb_serial *serial,
  97                           const struct usb_device_id *id)
  98 {
  99         struct usb_host_interface *iface_desc = serial->interface->
 100                                                                 cur_altsetting;
 101         struct usb_endpoint_descriptor *endpoint;
 102         int num_bulk_out = 0;
 103         int i;
 104
 105         for (i = 0; i < iface_desc->desc.bNumEndpoints; i++) {
 106                 endpoint = &iface_desc->endpoint[i].desc;
 107                 if (usb_endpoint_is_bulk_out(endpoint)) {
 108                         dev_dbg(&serial->dev->dev,
 109                                 "found bulk out on endpoint %d\n", i);
 110                         ++num_bulk_out;
 111                 }
 112         }
 113
 114         if (num_bulk_out == 0) {
 115                 dev_dbg(&serial->dev->dev, "Invalid interface, discarding\n");
 116                 return -ENODEV;
 117         }
 118
 119         return 0;
 120 }
 121
 122 static int aircable_process_packet(struct usb_serial_port *port,
 123                 int has_headers, char *packet, int len)
 124 {
 125         if (has_headers) {
 126                 len -= HCI_HEADER_LENGTH;
 127                 packet += HCI_HEADER_LENGTH;
 128         }
 129         if (len <= 0) {
 130                 dev_dbg(&port->dev, "%s - malformed packet\n", __func__);
 131                 return 0;
 132         }
 133
 134         tty_insert_flip_string(&port->port, packet, len);
 135
 136         return len;
 137 }
 138
 139 static void aircable_process_read_urb(struct urb *urb)
 140 {
 141         struct usb_serial_port *port = urb->context;
 142         char *data = (char *)urb->transfer_buffer;
 143         int has_headers;
 144         int count;
 145         int len;
 146         int i;
 147
 148         has_headers = (urb->actual_length > 2 && data[0] == RX_HEADER_0);
 149
 150         count = 0;
 151         for (i = 0; i < urb->actual_length; i += HCI_COMPLETE_FRAME) {
 152                 len = min_t(int, urb->actual_length - i, HCI_COMPLETE_FRAME);
 153                 count += aircable_process_packet(port, has_headers,
 154                                                                 &data[i], len);
 155         }
 156
 157         if (count)
 158                 tty_flip_buffer_push(&port->port);
 159 }
 160
 161 static struct usb_serial_driver aircable_device = {
 162         .driver = {
 163                 .owner =        THIS_MODULE,
 164                 .name =         "aircable",
 165         },
 166         .id_table =             id_table,
 167         .num_ports =            1,
 168         .bulk_out_size =        HCI_COMPLETE_FRAME,
 169         .probe =                aircable_probe,
 170         .process_read_urb =     aircable_process_read_urb,
 171         .prepare_write_buffer = aircable_prepare_write_buffer,
 172         .throttle =             usb_serial_generic_throttle,
 173         .unthrottle =           usb_serial_generic_unthrottle,
 174 };
 175
 176 static struct usb_serial_driver * const serial_drivers[] = {
 177         &aircable_device, NULL
 178 };
 179
 180 module_usb_serial_driver(serial_drivers, id_table);
 181
 182 MODULE_AUTHOR(DRIVER_AUTHOR);
 183 MODULE_DESCRIPTION(DRIVER_DESC);
 184 MODULE_LICENSE("GPL");