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 */
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