LXR linux/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/* 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 */
  75static const struct usb_device_id id_table[] = {
  76        { USB_DEVICE(AIRCABLE_VID, AIRCABLE_USB_PID) },
  77        { },
  78};
  79MODULE_DEVICE_TABLE(usb, id_table);
  80
  81static 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
  96static 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
 122static 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
 139static 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
 161static 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
 176static struct usb_serial_driver * const serial_drivers[] = {
 177        &aircable_device, NULL
 178};
 179
 180module_usb_serial_driver(serial_drivers, id_table);
 181
 182MODULE_AUTHOR(DRIVER_AUTHOR);
 183MODULE_DESCRIPTION(DRIVER_DESC);
 184MODULE_LICENSE("GPL");
 185