1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3  * USB Wishbone-Serial adapter driver
4  *
5  * Copyright (C) 2013 Wesley W. Terpstra <w.terpstra@gsi.de>
6  * Copyright (C) 2013 GSI Helmholtz Centre for Heavy Ion Research GmbH
7  */
8 
9 #include <linux/kernel.h>
10 #include <linux/tty.h>
11 #include <linux/module.h>
12 #include <linux/usb.h>
13 #include <linux/usb/serial.h>
14 #include <linux/uaccess.h>
15 
16 #define GSI_VENDOR_OPENCLOSE 0xB0
17 
18 static const struct usb_device_id id_table[] = {
19 	{ USB_DEVICE_AND_INTERFACE_INFO(0x1D50, 0x6062, 0xFF, 0xFF, 0xFF) },
20 	{ },
21 };
22 MODULE_DEVICE_TABLE(usb, id_table);
23 
24 /*
25  * Etherbone must be told that a new stream has begun before data arrives.
26  * This is necessary to restart the negotiation of Wishbone bus parameters.
27  * Similarly, when the stream ends, Etherbone must be told so that the cycle
28  * line can be driven low in the case that userspace failed to do so.
29  */
30 static int usb_gsi_openclose(struct usb_serial_port *port, int value)
31 {
32 	struct usb_device *dev = port->serial->dev;
33 
34 	return usb_control_msg(
35 		dev,
36 		usb_sndctrlpipe(dev, 0), /* Send to EP0OUT */
37 		GSI_VENDOR_OPENCLOSE,
38 		USB_DIR_OUT|USB_TYPE_VENDOR|USB_RECIP_INTERFACE,
39 		value, /* wValue = device is open(1) or closed(0) */
40 		port->serial->interface->cur_altsetting->desc.bInterfaceNumber,
41 		NULL, 0,  /* There is no data stage */
42 		5000); /* Timeout till operation fails */
43 }
44 
45 static int wishbone_serial_open(struct tty_struct *tty,
46 				struct usb_serial_port *port)
47 {
48 	int retval;
49 
50 	retval = usb_gsi_openclose(port, 1);
51 	if (retval) {
52 		dev_err(&port->serial->dev->dev,
53 		       "Could not mark device as open (%d)\n",
54 		       retval);
55 		return retval;
56 	}
57 
58 	retval = usb_serial_generic_open(tty, port);
59 	if (retval)
60 		usb_gsi_openclose(port, 0);
61 
62 	return retval;
63 }
64 
65 static void wishbone_serial_close(struct usb_serial_port *port)
66 {
67 	usb_serial_generic_close(port);
68 	usb_gsi_openclose(port, 0);
69 }
70 
71 static struct usb_serial_driver wishbone_serial_device = {
72 	.driver = {
73 		.owner =	THIS_MODULE,
74 		.name =		"wishbone_serial",
75 	},
76 	.id_table =		id_table,
77 	.num_ports =		1,
78 	.open =			&wishbone_serial_open,
79 	.close =		&wishbone_serial_close,
80 };
81 
82 static struct usb_serial_driver * const serial_drivers[] = {
83 	&wishbone_serial_device, NULL
84 };
85 
86 module_usb_serial_driver(serial_drivers, id_table);
87 
88 MODULE_AUTHOR("Wesley W. Terpstra <w.terpstra@gsi.de>");
89 MODULE_DESCRIPTION("USB Wishbone-Serial adapter");
90 MODULE_LICENSE("GPL");
91