1/*
2 * Symbol USB barcode to serial driver
3 *
4 * Copyright (C) 2013 Johan Hovold <jhovold@gmail.com>
5 * Copyright (C) 2009 Greg Kroah-Hartman <gregkh@suse.de>
6 * Copyright (C) 2009 Novell Inc.
7 *
8 *	This program is free software; you can redistribute it and/or
9 *	modify it under the terms of the GNU General Public License version
10 *	2 as published by the Free Software Foundation.
11 */
12
13#include <linux/kernel.h>
14#include <linux/tty.h>
15#include <linux/slab.h>
16#include <linux/tty_driver.h>
17#include <linux/tty_flip.h>
18#include <linux/module.h>
19#include <linux/usb.h>
20#include <linux/usb/serial.h>
21#include <linux/uaccess.h>
22
23static const struct usb_device_id id_table[] = {
24	{ USB_DEVICE(0x05e0, 0x0600) },
25	{ },
26};
27MODULE_DEVICE_TABLE(usb, id_table);
28
29struct symbol_private {
30	spinlock_t lock;	/* protects the following flags */
31	bool throttled;
32	bool actually_throttled;
33};
34
35static void symbol_int_callback(struct urb *urb)
36{
37	struct usb_serial_port *port = urb->context;
38	struct symbol_private *priv = usb_get_serial_port_data(port);
39	unsigned char *data = urb->transfer_buffer;
40	int status = urb->status;
41	int result;
42	int data_length;
43
44	switch (status) {
45	case 0:
46		/* success */
47		break;
48	case -ECONNRESET:
49	case -ENOENT:
50	case -ESHUTDOWN:
51		/* this urb is terminated, clean up */
52		dev_dbg(&port->dev, "%s - urb shutting down with status: %d\n",
53			__func__, status);
54		return;
55	default:
56		dev_dbg(&port->dev, "%s - nonzero urb status received: %d\n",
57			__func__, status);
58		goto exit;
59	}
60
61	usb_serial_debug_data(&port->dev, __func__, urb->actual_length, data);
62
63	if (urb->actual_length > 1) {
64		data_length = urb->actual_length - 1;
65
66		/*
67		 * Data from the device comes with a 1 byte header:
68		 *
69		 * <size of data>data...
70		 * 	This is real data to be sent to the tty layer
71		 * we pretty much just ignore the size and send everything
72		 * else to the tty layer.
73		 */
74		tty_insert_flip_string(&port->port, &data[1], data_length);
75		tty_flip_buffer_push(&port->port);
76	} else {
77		dev_dbg(&port->dev, "%s - short packet\n", __func__);
78	}
79
80exit:
81	spin_lock(&priv->lock);
82
83	/* Continue trying to always read if we should */
84	if (!priv->throttled) {
85		result = usb_submit_urb(port->interrupt_in_urb, GFP_ATOMIC);
86		if (result)
87			dev_err(&port->dev,
88			    "%s - failed resubmitting read urb, error %d\n",
89							__func__, result);
90	} else
91		priv->actually_throttled = true;
92	spin_unlock(&priv->lock);
93}
94
95static int symbol_open(struct tty_struct *tty, struct usb_serial_port *port)
96{
97	struct symbol_private *priv = usb_get_serial_port_data(port);
98	unsigned long flags;
99	int result = 0;
100
101	spin_lock_irqsave(&priv->lock, flags);
102	priv->throttled = false;
103	priv->actually_throttled = false;
104	spin_unlock_irqrestore(&priv->lock, flags);
105
106	/* Start reading from the device */
107	result = usb_submit_urb(port->interrupt_in_urb, GFP_KERNEL);
108	if (result)
109		dev_err(&port->dev,
110			"%s - failed resubmitting read urb, error %d\n",
111			__func__, result);
112	return result;
113}
114
115static void symbol_close(struct usb_serial_port *port)
116{
117	usb_kill_urb(port->interrupt_in_urb);
118}
119
120static void symbol_throttle(struct tty_struct *tty)
121{
122	struct usb_serial_port *port = tty->driver_data;
123	struct symbol_private *priv = usb_get_serial_port_data(port);
124
125	spin_lock_irq(&priv->lock);
126	priv->throttled = true;
127	spin_unlock_irq(&priv->lock);
128}
129
130static void symbol_unthrottle(struct tty_struct *tty)
131{
132	struct usb_serial_port *port = tty->driver_data;
133	struct symbol_private *priv = usb_get_serial_port_data(port);
134	int result;
135	bool was_throttled;
136
137	spin_lock_irq(&priv->lock);
138	priv->throttled = false;
139	was_throttled = priv->actually_throttled;
140	priv->actually_throttled = false;
141	spin_unlock_irq(&priv->lock);
142
143	if (was_throttled) {
144		result = usb_submit_urb(port->interrupt_in_urb, GFP_KERNEL);
145		if (result)
146			dev_err(&port->dev,
147				"%s - failed submitting read urb, error %d\n",
148							__func__, result);
149	}
150}
151
152static int symbol_startup(struct usb_serial *serial)
153{
154	if (!serial->num_interrupt_in) {
155		dev_err(&serial->dev->dev, "no interrupt-in endpoint\n");
156		return -ENODEV;
157	}
158
159	return 0;
160}
161
162static int symbol_port_probe(struct usb_serial_port *port)
163{
164	struct symbol_private *priv;
165
166	priv = kzalloc(sizeof(*priv), GFP_KERNEL);
167	if (!priv)
168		return -ENOMEM;
169
170	spin_lock_init(&priv->lock);
171
172	usb_set_serial_port_data(port, priv);
173
174	return 0;
175}
176
177static int symbol_port_remove(struct usb_serial_port *port)
178{
179	struct symbol_private *priv = usb_get_serial_port_data(port);
180
181	kfree(priv);
182
183	return 0;
184}
185
186static struct usb_serial_driver symbol_device = {
187	.driver = {
188		.owner =	THIS_MODULE,
189		.name =		"symbol",
190	},
191	.id_table =		id_table,
192	.num_ports =		1,
193	.attach =		symbol_startup,
194	.port_probe =		symbol_port_probe,
195	.port_remove =		symbol_port_remove,
196	.open =			symbol_open,
197	.close =		symbol_close,
198	.throttle = 		symbol_throttle,
199	.unthrottle =		symbol_unthrottle,
200	.read_int_callback =	symbol_int_callback,
201};
202
203static struct usb_serial_driver * const serial_drivers[] = {
204	&symbol_device, NULL
205};
206
207module_usb_serial_driver(serial_drivers, id_table);
208
209MODULE_LICENSE("GPL");
210