summaryrefslogtreecommitdiffstats
path: root/drivers/usb/serial/aircable.c
blob: d634e6635632f8601fa943982a24f8c995ab320b (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
/*
 * AIRcable USB Bluetooth Dongle Driver.
 *
 * Copyright (C) 2010 Johan Hovold <jhovold@gmail.com>
 * Copyright (C) 2006 Manuel Francisco Naranjo (naranjo.manuel@gmail.com)
 *
 * This program is free software; you can redistribute it and/or modify it under
 * the terms of the GNU General Public License version 2 as published by the
 * Free Software Foundation.
 *
 * The device works as an standard CDC device, it has 2 interfaces, the first
 * one is for firmware access and the second is the serial one.
 * The protocol is very simply, there are two posibilities reading or writing.
 * When writing the first urb must have a Header that starts with 0x20 0x29 the
 * next two bytes must say how much data will be sended.
 * When reading the process is almost equal except that the header starts with
 * 0x00 0x20.
 *
 * The device simply need some stuff to understand data coming from the usb
 * buffer: The First and Second byte is used for a Header, the Third and Fourth
 * tells the  device the amount of information the package holds.
 * Packages are 60 bytes long Header Stuff.
 * When writing to the device the first two bytes of the header are 0x20 0x29
 * When reading the bytes are 0x00 0x20, or 0x00 0x10, there is an strange
 * situation, when too much data arrives to the device because it sends the data
 * but with out the header. I will use a simply hack to override this situation,
 * if there is data coming that does not contain any header, then that is data
 * that must go directly to the tty, as there is no documentation about if there
 * is any other control code, I will simply check for the first
 * one.
 *
 * The driver registers himself with the USB-serial core and the USB Core. I had
 * to implement a probe function against USB-serial, because other way, the
 * driver was attaching himself to both interfaces. I have tryed with different
 * configurations of usb_serial_driver with out exit, only the probe function
 * could handle this correctly.
 *
 * I have taken some info from a Greg Kroah-Hartman article:
 * http://www.linuxjournal.com/article/6573
 * And from Linux Device Driver Kit CD, which is a great work, the authors taken
 * the work to recompile lots of information an knowladge in drivers development
 * and made it all avaible inside a cd.
 * URL: http://kernel.org/pub/linux/kernel/people/gregkh/ddk/
 *
 */

#include <asm/unaligned.h>
#include <linux/tty.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/tty_flip.h>
#include <linux/usb.h>
#include <linux/usb/serial.h>

static bool debug;

/* Vendor and Product ID */
#define AIRCABLE_VID		0x16CA
#define AIRCABLE_USB_PID	0x1502

/* Protocol Stuff */
#define HCI_HEADER_LENGTH	0x4
#define TX_HEADER_0		0x20
#define TX_HEADER_1		0x29
#define RX_HEADER_0		0x00
#define RX_HEADER_1		0x20
#define HCI_COMPLETE_FRAME	64

/* rx_flags */
#define THROTTLED		0x01
#define ACTUALLY_THROTTLED	0x02

/*
 * Version Information
 */
#define DRIVER_VERSION "v2.0"
#define DRIVER_AUTHOR "Naranjo, Manuel Francisco <naranjo.manuel@gmail.com>, Johan Hovold <jhovold@gmail.com>"
#define DRIVER_DESC "AIRcable USB Driver"

/* ID table that will be registered with USB core */
static const struct usb_device_id id_table[] = {
	{ USB_DEVICE(AIRCABLE_VID, AIRCABLE_USB_PID) },
	{ },
};
MODULE_DEVICE_TABLE(usb, id_table);

static int aircable_prepare_write_buffer(struct usb_serial_port *port,
						void *dest, size_t size)
{
	int count;
	unsigned char *buf = dest;

	count = kfifo_out_locked(&port->write_fifo, buf + HCI_HEADER_LENGTH,
					size - HCI_HEADER_LENGTH, &port->lock);
	buf[0] = TX_HEADER_0;
	buf[1] = TX_HEADER_1;
	put_unaligned_le16(count, &buf[2]);

	return count + HCI_HEADER_LENGTH;
}

static int aircable_probe(struct usb_serial *serial,
			  const struct usb_device_id *id)
{
	struct usb_host_interface *iface_desc = serial->interface->
								cur_altsetting;
	struct usb_endpoint_descriptor *endpoint;
	int num_bulk_out = 0;
	int i;

	for (i = 0; i < iface_desc->desc.bNumEndpoints; i++) {
		endpoint = &iface_desc->endpoint[i].desc;
		if (usb_endpoint_is_bulk_out(endpoint)) {
			dev_dbg(&serial->dev->dev,
				"found bulk out on endpoint %d\n", i);
			++num_bulk_out;
		}
	}

	if (num_bulk_out == 0) {
		dev_dbg(&serial->dev->dev, "Invalid interface, discarding\n");
		return -ENODEV;
	}

	return 0;
}

static int aircable_process_packet(struct tty_struct *tty,
			struct usb_serial_port *port, int has_headers,
			char *packet, int len)
{
	if (has_headers) {
		len -= HCI_HEADER_LENGTH;
		packet += HCI_HEADER_LENGTH;
	}
	if (len <= 0) {
		dev_dbg(&port->dev, "%s - malformed packet\n", __func__);
		return 0;
	}

	tty_insert_flip_string(tty, packet, len);

	return len;
}

static void aircable_process_read_urb(struct urb *urb)
{
	struct usb_serial_port *port = urb->context;
	char *data = (char *)urb->transfer_buffer;
	struct tty_struct *tty;
	int has_headers;
	int count;
	int len;
	int i;

	tty = tty_port_tty_get(&port->port);
	if (!tty)
		return;

	has_headers = (urb->actual_length > 2 && data[0] == RX_HEADER_0);

	count = 0;
	for (i = 0; i < urb->actual_length; i += HCI_COMPLETE_FRAME) {
		len = min_t(int, urb->actual_length - i, HCI_COMPLETE_FRAME);
		count += aircable_process_packet(tty, port, has_headers,
								&data[i], len);
	}

	if (count)
		tty_flip_buffer_push(tty);
	tty_kref_put(tty);
}

static struct usb_serial_driver aircable_device = {
	.driver = {
		.owner =	THIS_MODULE,
		.name =		"aircable",
	},
	.id_table = 		id_table,
	.num_ports =		1,
	.bulk_out_size =	HCI_COMPLETE_FRAME,
	.probe =		aircable_probe,
	.process_read_urb =	aircable_process_read_urb,
	.prepare_write_buffer =	aircable_prepare_write_buffer,
	.throttle =		usb_serial_generic_throttle,
	.unthrottle =		usb_serial_generic_unthrottle,
};

static struct usb_serial_driver * const serial_drivers[] = {
	&aircable_device, NULL
};

module_usb_serial_driver(serial_drivers, id_table);

MODULE_AUTHOR(DRIVER_AUTHOR);
MODULE_DESCRIPTION(DRIVER_DESC);
MODULE_VERSION(DRIVER_VERSION);
MODULE_LICENSE("GPL");

module_param(debug, bool, S_IRUGO | S_IWUSR);
MODULE_PARM_DESC(debug, "Debug enabled or not");