xref: /openbmc/linux/drivers/usb/serial/aircable.c (revision eb0c68ea)
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * AIRcable USB Bluetooth Dongle Driver.
4  *
5  * Copyright (C) 2010 Johan Hovold <jhovold@gmail.com>
6  * Copyright (C) 2006 Manuel Francisco Naranjo (naranjo.manuel@gmail.com)
7  *
8  * The device works as an standard CDC device, it has 2 interfaces, the first
9  * one is for firmware access and the second is the serial one.
10  * The protocol is very simply, there are two possibilities reading or writing.
11  * When writing the first urb must have a Header that starts with 0x20 0x29 the
12  * next two bytes must say how much data will be sent.
13  * When reading the process is almost equal except that the header starts with
14  * 0x00 0x20.
15  *
16  * The device simply need some stuff to understand data coming from the usb
17  * buffer: The First and Second byte is used for a Header, the Third and Fourth
18  * tells the  device the amount of information the package holds.
19  * Packages are 60 bytes long Header Stuff.
20  * When writing to the device the first two bytes of the header are 0x20 0x29
21  * When reading the bytes are 0x00 0x20, or 0x00 0x10, there is an strange
22  * situation, when too much data arrives to the device because it sends the data
23  * but with out the header. I will use a simply hack to override this situation,
24  * if there is data coming that does not contain any header, then that is data
25  * that must go directly to the tty, as there is no documentation about if there
26  * is any other control code, I will simply check for the first
27  * one.
28  *
29  * I have taken some info from a Greg Kroah-Hartman article:
30  * http://www.linuxjournal.com/article/6573
31  * And from Linux Device Driver Kit CD, which is a great work, the authors taken
32  * the work to recompile lots of information an knowledge in drivers development
33  * and made it all available inside a cd.
34  * URL: http://kernel.org/pub/linux/kernel/people/gregkh/ddk/
35  *
36  */
37 
38 #include <asm/unaligned.h>
39 #include <linux/tty.h>
40 #include <linux/slab.h>
41 #include <linux/module.h>
42 #include <linux/tty_flip.h>
43 #include <linux/usb.h>
44 #include <linux/usb/serial.h>
45 
46 /* Vendor and Product ID */
47 #define AIRCABLE_VID		0x16CA
48 #define AIRCABLE_USB_PID	0x1502
49 
50 /* Protocol Stuff */
51 #define HCI_HEADER_LENGTH	0x4
52 #define TX_HEADER_0		0x20
53 #define TX_HEADER_1		0x29
54 #define RX_HEADER_0		0x00
55 #define RX_HEADER_1		0x20
56 #define HCI_COMPLETE_FRAME	64
57 
58 /* rx_flags */
59 #define THROTTLED		0x01
60 #define ACTUALLY_THROTTLED	0x02
61 
62 #define DRIVER_AUTHOR "Naranjo, Manuel Francisco <naranjo.manuel@gmail.com>, Johan Hovold <jhovold@gmail.com>"
63 #define DRIVER_DESC "AIRcable USB Driver"
64 
65 /* ID table that will be registered with USB core */
66 static const struct usb_device_id id_table[] = {
67 	{ USB_DEVICE(AIRCABLE_VID, AIRCABLE_USB_PID) },
68 	{ },
69 };
70 MODULE_DEVICE_TABLE(usb, id_table);
71 
aircable_prepare_write_buffer(struct usb_serial_port * port,void * dest,size_t size)72 static int aircable_prepare_write_buffer(struct usb_serial_port *port,
73 						void *dest, size_t size)
74 {
75 	int count;
76 	unsigned char *buf = dest;
77 
78 	count = kfifo_out_locked(&port->write_fifo, buf + HCI_HEADER_LENGTH,
79 					size - HCI_HEADER_LENGTH, &port->lock);
80 	buf[0] = TX_HEADER_0;
81 	buf[1] = TX_HEADER_1;
82 	put_unaligned_le16(count, &buf[2]);
83 
84 	return count + HCI_HEADER_LENGTH;
85 }
86 
aircable_calc_num_ports(struct usb_serial * serial,struct usb_serial_endpoints * epds)87 static int aircable_calc_num_ports(struct usb_serial *serial,
88 					struct usb_serial_endpoints *epds)
89 {
90 	/* Ignore the first interface, which has no bulk endpoints. */
91 	if (epds->num_bulk_out == 0) {
92 		dev_dbg(&serial->interface->dev,
93 			"ignoring interface with no bulk-out endpoints\n");
94 		return -ENODEV;
95 	}
96 
97 	return 1;
98 }
99 
aircable_process_packet(struct usb_serial_port * port,int has_headers,char * packet,int len)100 static int aircable_process_packet(struct usb_serial_port *port,
101 		int has_headers, char *packet, int len)
102 {
103 	if (has_headers) {
104 		len -= HCI_HEADER_LENGTH;
105 		packet += HCI_HEADER_LENGTH;
106 	}
107 	if (len <= 0) {
108 		dev_dbg(&port->dev, "%s - malformed packet\n", __func__);
109 		return 0;
110 	}
111 
112 	tty_insert_flip_string(&port->port, packet, len);
113 
114 	return len;
115 }
116 
aircable_process_read_urb(struct urb * urb)117 static void aircable_process_read_urb(struct urb *urb)
118 {
119 	struct usb_serial_port *port = urb->context;
120 	char *data = urb->transfer_buffer;
121 	int has_headers;
122 	int count;
123 	int len;
124 	int i;
125 
126 	has_headers = (urb->actual_length > 2 && data[0] == RX_HEADER_0);
127 
128 	count = 0;
129 	for (i = 0; i < urb->actual_length; i += HCI_COMPLETE_FRAME) {
130 		len = min_t(int, urb->actual_length - i, HCI_COMPLETE_FRAME);
131 		count += aircable_process_packet(port, has_headers,
132 								&data[i], len);
133 	}
134 
135 	if (count)
136 		tty_flip_buffer_push(&port->port);
137 }
138 
139 static struct usb_serial_driver aircable_device = {
140 	.driver = {
141 		.owner =	THIS_MODULE,
142 		.name =		"aircable",
143 	},
144 	.id_table = 		id_table,
145 	.bulk_out_size =	HCI_COMPLETE_FRAME,
146 	.calc_num_ports =	aircable_calc_num_ports,
147 	.process_read_urb =	aircable_process_read_urb,
148 	.prepare_write_buffer =	aircable_prepare_write_buffer,
149 	.throttle =		usb_serial_generic_throttle,
150 	.unthrottle =		usb_serial_generic_unthrottle,
151 };
152 
153 static struct usb_serial_driver * const serial_drivers[] = {
154 	&aircable_device, NULL
155 };
156 
157 module_usb_serial_driver(serial_drivers, id_table);
158 
159 MODULE_AUTHOR(DRIVER_AUTHOR);
160 MODULE_DESCRIPTION(DRIVER_DESC);
161 MODULE_LICENSE("GPL v2");
162