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
55static 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 */
81static const struct usb_device_id id_table[] = {
82	{ USB_DEVICE(AIRCABLE_VID, AIRCABLE_USB_PID) },
83	{ },
84};
85MODULE_DEVICE_TABLE(usb, id_table);
86
87static 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
102static 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			dbg("found bulk out on endpoint %d", i);
115			++num_bulk_out;
116		}
117	}
118
119	if (num_bulk_out == 0) {
120		dbg("Invalid interface, discarding");
121		return -ENODEV;
122	}
123
124	return 0;
125}
126
127static int aircable_process_packet(struct tty_struct *tty,
128			struct usb_serial_port *port, int has_headers,
129			char *packet, int len)
130{
131	if (has_headers) {
132		len -= HCI_HEADER_LENGTH;
133		packet += HCI_HEADER_LENGTH;
134	}
135	if (len <= 0) {
136		dbg("%s - malformed packet", __func__);
137		return 0;
138	}
139
140	tty_insert_flip_string(tty, packet, len);
141
142	return len;
143}
144
145static void aircable_process_read_urb(struct urb *urb)
146{
147	struct usb_serial_port *port = urb->context;
148	char *data = (char *)urb->transfer_buffer;
149	struct tty_struct *tty;
150	int has_headers;
151	int count;
152	int len;
153	int i;
154
155	tty = tty_port_tty_get(&port->port);
156	if (!tty)
157		return;
158
159	has_headers = (urb->actual_length > 2 && data[0] == RX_HEADER_0);
160
161	count = 0;
162	for (i = 0; i < urb->actual_length; i += HCI_COMPLETE_FRAME) {
163		len = min_t(int, urb->actual_length - i, HCI_COMPLETE_FRAME);
164		count += aircable_process_packet(tty, port, has_headers,
165								&data[i], len);
166	}
167
168	if (count)
169		tty_flip_buffer_push(tty);
170	tty_kref_put(tty);
171}
172
173static struct usb_driver aircable_driver = {
174	.name =		"aircable",
175	.probe =	usb_serial_probe,
176	.disconnect =	usb_serial_disconnect,
177	.id_table =	id_table,
178};
179
180static struct usb_serial_driver aircable_device = {
181	.driver = {
182		.owner =	THIS_MODULE,
183		.name =		"aircable",
184	},
185	.id_table = 		id_table,
186	.num_ports =		1,
187	.bulk_out_size =	HCI_COMPLETE_FRAME,
188	.probe =		aircable_probe,
189	.process_read_urb =	aircable_process_read_urb,
190	.prepare_write_buffer =	aircable_prepare_write_buffer,
191	.throttle =		usb_serial_generic_throttle,
192	.unthrottle =		usb_serial_generic_unthrottle,
193};
194
195static struct usb_serial_driver * const serial_drivers[] = {
196	&aircable_device, NULL
197};
198
199module_usb_serial_driver(aircable_driver, serial_drivers);
200
201MODULE_AUTHOR(DRIVER_AUTHOR);
202MODULE_DESCRIPTION(DRIVER_DESC);
203MODULE_VERSION(DRIVER_VERSION);
204MODULE_LICENSE("GPL");
205
206module_param(debug, bool, S_IRUGO | S_IWUSR);
207MODULE_PARM_DESC(debug, "Debug enabled or not");
208