xref: /linux/drivers/usb/serial/aircable.c (revision b889fcf63cb62e7fdb7816565e28f44dbe4a76a5)
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 */
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 tty_struct *tty,
123 			struct usb_serial_port *port, int has_headers,
124 			char *packet, int len)
125 {
126 	if (has_headers) {
127 		len -= HCI_HEADER_LENGTH;
128 		packet += HCI_HEADER_LENGTH;
129 	}
130 	if (len <= 0) {
131 		dev_dbg(&port->dev, "%s - malformed packet\n", __func__);
132 		return 0;
133 	}
134 
135 	tty_insert_flip_string(tty, packet, len);
136 
137 	return len;
138 }
139 
140 static void aircable_process_read_urb(struct urb *urb)
141 {
142 	struct usb_serial_port *port = urb->context;
143 	char *data = (char *)urb->transfer_buffer;
144 	struct tty_struct *tty;
145 	int has_headers;
146 	int count;
147 	int len;
148 	int i;
149 
150 	tty = tty_port_tty_get(&port->port);
151 	if (!tty)
152 		return;
153 
154 	has_headers = (urb->actual_length > 2 && data[0] == RX_HEADER_0);
155 
156 	count = 0;
157 	for (i = 0; i < urb->actual_length; i += HCI_COMPLETE_FRAME) {
158 		len = min_t(int, urb->actual_length - i, HCI_COMPLETE_FRAME);
159 		count += aircable_process_packet(tty, port, has_headers,
160 								&data[i], len);
161 	}
162 
163 	if (count)
164 		tty_flip_buffer_push(tty);
165 	tty_kref_put(tty);
166 }
167 
168 static struct usb_serial_driver aircable_device = {
169 	.driver = {
170 		.owner =	THIS_MODULE,
171 		.name =		"aircable",
172 	},
173 	.id_table = 		id_table,
174 	.num_ports =		1,
175 	.bulk_out_size =	HCI_COMPLETE_FRAME,
176 	.probe =		aircable_probe,
177 	.process_read_urb =	aircable_process_read_urb,
178 	.prepare_write_buffer =	aircable_prepare_write_buffer,
179 	.throttle =		usb_serial_generic_throttle,
180 	.unthrottle =		usb_serial_generic_unthrottle,
181 };
182 
183 static struct usb_serial_driver * const serial_drivers[] = {
184 	&aircable_device, NULL
185 };
186 
187 module_usb_serial_driver(serial_drivers, id_table);
188 
189 MODULE_AUTHOR(DRIVER_AUTHOR);
190 MODULE_DESCRIPTION(DRIVER_DESC);
191 MODULE_LICENSE("GPL");
192