1 /*
2  * USB Wishbone-Serial adapter driver
3  *
4  * Copyright (C) 2013 Wesley W. Terpstra <w.terpstra@gsi.de>
5  * Copyright (C) 2013 GSI Helmholtz Centre for Heavy Ion Research GmbH
6  *
7  * This program is free software; you can redistribute it and/or
8  * modify it under the terms of the GNU General Public License
9  * as published by the Free Software Foundation; either version 2
10  * of the License, or (at your option) any later version.
11  */
12 
13 #include <linux/kernel.h>
14 #include <linux/tty.h>
15 #include <linux/module.h>
16 #include <linux/usb.h>
17 #include <linux/usb/serial.h>
18 #include <linux/uaccess.h>
19 
20 #define GSI_VENDOR_OPENCLOSE 0xB0
21 
22 static const struct usb_device_id id_table[] = {
23 	{ USB_DEVICE_AND_INTERFACE_INFO(0x1D50, 0x6062, 0xFF, 0xFF, 0xFF) },
24 	{ },
25 };
26 MODULE_DEVICE_TABLE(usb, id_table);
27 
28 /*
29  * Etherbone must be told that a new stream has begun before data arrives.
30  * This is necessary to restart the negotiation of Wishbone bus parameters.
31  * Similarly, when the stream ends, Etherbone must be told so that the cycle
32  * line can be driven low in the case that userspace failed to do so.
33  */
34 static int usb_gsi_openclose(struct usb_serial_port *port, int value)
35 {
36 	struct usb_device *dev = port->serial->dev;
37 
38 	return usb_control_msg(
39 		dev,
40 		usb_sndctrlpipe(dev, 0), /* Send to EP0OUT */
41 		GSI_VENDOR_OPENCLOSE,
42 		USB_DIR_OUT|USB_TYPE_VENDOR|USB_RECIP_INTERFACE,
43 		value, /* wValue = device is open(1) or closed(0) */
44 		port->serial->interface->cur_altsetting->desc.bInterfaceNumber,
45 		NULL, 0,  /* There is no data stage */
46 		5000); /* Timeout till operation fails */
47 }
48 
49 static int wishbone_serial_open(struct tty_struct *tty,
50 				struct usb_serial_port *port)
51 {
52 	int retval;
53 
54 	retval = usb_gsi_openclose(port, 1);
55 	if (retval) {
56 		dev_err(&port->serial->dev->dev,
57 		       "Could not mark device as open (%d)\n",
58 		       retval);
59 		return retval;
60 	}
61 
62 	retval = usb_serial_generic_open(tty, port);
63 	if (retval)
64 		usb_gsi_openclose(port, 0);
65 
66 	return retval;
67 }
68 
69 static void wishbone_serial_close(struct usb_serial_port *port)
70 {
71 	usb_serial_generic_close(port);
72 	usb_gsi_openclose(port, 0);
73 }
74 
75 static struct usb_serial_driver wishbone_serial_device = {
76 	.driver = {
77 		.owner =	THIS_MODULE,
78 		.name =		"wishbone_serial",
79 	},
80 	.id_table =		id_table,
81 	.num_ports =		1,
82 	.open =			&wishbone_serial_open,
83 	.close =		&wishbone_serial_close,
84 };
85 
86 static struct usb_serial_driver * const serial_drivers[] = {
87 	&wishbone_serial_device, NULL
88 };
89 
90 module_usb_serial_driver(serial_drivers, id_table);
91 
92 MODULE_AUTHOR("Wesley W. Terpstra <w.terpstra@gsi.de>");
93 MODULE_DESCRIPTION("USB Wishbone-Serial adapter");
94 MODULE_LICENSE("GPL");
95