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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 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");
185 

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