1/*
2 * Input device TTY line discipline
3 *
4 * Copyright (c) 1999-2002 Vojtech Pavlik
5 *
6 * This is a module that converts a tty line into a much simpler
7 * 'serial io port' abstraction that the input device drivers use.
8 */
9
10/*
11 * This program is free software; you can redistribute it and/or modify it
12 * under the terms of the GNU General Public License version 2 as published by
13 * the Free Software Foundation.
14 */
15
16#include <asm/uaccess.h>
17#include <linux/kernel.h>
18#include <linux/sched.h>
19#include <linux/slab.h>
20#include <linux/module.h>
21#include <linux/init.h>
22#include <linux/serio.h>
23#include <linux/tty.h>
24#include <linux/compat.h>
25
26MODULE_AUTHOR("Vojtech Pavlik <vojtech@ucw.cz>");
27MODULE_DESCRIPTION("Input device TTY line discipline");
28MODULE_LICENSE("GPL");
29MODULE_ALIAS_LDISC(N_MOUSE);
30
31#define SERPORT_BUSY	1
32#define SERPORT_ACTIVE	2
33#define SERPORT_DEAD	3
34
35struct serport {
36	struct tty_struct *tty;
37	wait_queue_head_t wait;
38	struct serio *serio;
39	struct serio_device_id id;
40	spinlock_t lock;
41	unsigned long flags;
42};
43
44/*
45 * Callback functions from the serio code.
46 */
47
48static int serport_serio_write(struct serio *serio, unsigned char data)
49{
50	struct serport *serport = serio->port_data;
51	return -(serport->tty->ops->write(serport->tty, &data, 1) != 1);
52}
53
54static int serport_serio_open(struct serio *serio)
55{
56	struct serport *serport = serio->port_data;
57	unsigned long flags;
58
59	spin_lock_irqsave(&serport->lock, flags);
60	set_bit(SERPORT_ACTIVE, &serport->flags);
61	spin_unlock_irqrestore(&serport->lock, flags);
62
63	return 0;
64}
65
66
67static void serport_serio_close(struct serio *serio)
68{
69	struct serport *serport = serio->port_data;
70	unsigned long flags;
71
72	spin_lock_irqsave(&serport->lock, flags);
73	clear_bit(SERPORT_ACTIVE, &serport->flags);
74	set_bit(SERPORT_DEAD, &serport->flags);
75	spin_unlock_irqrestore(&serport->lock, flags);
76
77	wake_up_interruptible(&serport->wait);
78}
79
80/*
81 * serport_ldisc_open() is the routine that is called upon setting our line
82 * discipline on a tty. It prepares the serio struct.
83 */
84
85static int serport_ldisc_open(struct tty_struct *tty)
86{
87	struct serport *serport;
88
89	if (!capable(CAP_SYS_ADMIN))
90		return -EPERM;
91
92	serport = kzalloc(sizeof(struct serport), GFP_KERNEL);
93	if (!serport)
94		return -ENOMEM;
95
96	serport->tty = tty;
97	spin_lock_init(&serport->lock);
98	init_waitqueue_head(&serport->wait);
99
100	tty->disc_data = serport;
101	tty->receive_room = 256;
102	set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
103
104	return 0;
105}
106
107/*
108 * serport_ldisc_close() is the opposite of serport_ldisc_open()
109 */
110
111static void serport_ldisc_close(struct tty_struct *tty)
112{
113	struct serport *serport = (struct serport *) tty->disc_data;
114
115	kfree(serport);
116}
117
118/*
119 * serport_ldisc_receive() is called by the low level tty driver when characters
120 * are ready for us. We forward the characters and flags, one by one to the
121 * 'interrupt' routine.
122 */
123
124static void serport_ldisc_receive(struct tty_struct *tty, const unsigned char *cp, char *fp, int count)
125{
126	struct serport *serport = (struct serport*) tty->disc_data;
127	unsigned long flags;
128	unsigned int ch_flags = 0;
129	int i;
130
131	spin_lock_irqsave(&serport->lock, flags);
132
133	if (!test_bit(SERPORT_ACTIVE, &serport->flags))
134		goto out;
135
136	for (i = 0; i < count; i++) {
137		if (fp) {
138			switch (fp[i]) {
139			case TTY_FRAME:
140				ch_flags = SERIO_FRAME;
141				break;
142
143			case TTY_PARITY:
144				ch_flags = SERIO_PARITY;
145				break;
146
147			default:
148				ch_flags = 0;
149				break;
150			}
151		}
152
153		serio_interrupt(serport->serio, cp[i], ch_flags);
154	}
155
156out:
157	spin_unlock_irqrestore(&serport->lock, flags);
158}
159
160/*
161 * serport_ldisc_read() just waits indefinitely if everything goes well.
162 * However, when the serio driver closes the serio port, it finishes,
163 * returning 0 characters.
164 */
165
166static ssize_t serport_ldisc_read(struct tty_struct * tty, struct file * file, unsigned char __user * buf, size_t nr)
167{
168	struct serport *serport = (struct serport*) tty->disc_data;
169	struct serio *serio;
170
171	if (test_and_set_bit(SERPORT_BUSY, &serport->flags))
172		return -EBUSY;
173
174	serport->serio = serio = kzalloc(sizeof(struct serio), GFP_KERNEL);
175	if (!serio)
176		return -ENOMEM;
177
178	strlcpy(serio->name, "Serial port", sizeof(serio->name));
179	snprintf(serio->phys, sizeof(serio->phys), "%s/serio0", tty_name(tty));
180	serio->id = serport->id;
181	serio->id.type = SERIO_RS232;
182	serio->write = serport_serio_write;
183	serio->open = serport_serio_open;
184	serio->close = serport_serio_close;
185	serio->port_data = serport;
186	serio->dev.parent = tty->dev;
187
188	serio_register_port(serport->serio);
189	printk(KERN_INFO "serio: Serial port %s\n", tty_name(tty));
190
191	wait_event_interruptible(serport->wait, test_bit(SERPORT_DEAD, &serport->flags));
192	serio_unregister_port(serport->serio);
193	serport->serio = NULL;
194
195	clear_bit(SERPORT_DEAD, &serport->flags);
196	clear_bit(SERPORT_BUSY, &serport->flags);
197
198	return 0;
199}
200
201static void serport_set_type(struct tty_struct *tty, unsigned long type)
202{
203	struct serport *serport = tty->disc_data;
204
205	serport->id.proto = type & 0x000000ff;
206	serport->id.id    = (type & 0x0000ff00) >> 8;
207	serport->id.extra = (type & 0x00ff0000) >> 16;
208}
209
210/*
211 * serport_ldisc_ioctl() allows to set the port protocol, and device ID
212 */
213
214static int serport_ldisc_ioctl(struct tty_struct *tty, struct file *file,
215			       unsigned int cmd, unsigned long arg)
216{
217	if (cmd == SPIOCSTYPE) {
218		unsigned long type;
219
220		if (get_user(type, (unsigned long __user *) arg))
221			return -EFAULT;
222
223		serport_set_type(tty, type);
224		return 0;
225	}
226
227	return -EINVAL;
228}
229
230#ifdef CONFIG_COMPAT
231#define COMPAT_SPIOCSTYPE	_IOW('q', 0x01, compat_ulong_t)
232static long serport_ldisc_compat_ioctl(struct tty_struct *tty,
233				       struct file *file,
234				       unsigned int cmd, unsigned long arg)
235{
236	if (cmd == COMPAT_SPIOCSTYPE) {
237		void __user *uarg = compat_ptr(arg);
238		compat_ulong_t compat_type;
239
240		if (get_user(compat_type, (compat_ulong_t __user *)uarg))
241			return -EFAULT;
242
243		serport_set_type(tty, compat_type);
244		return 0;
245	}
246
247	return -EINVAL;
248}
249#endif
250
251static void serport_ldisc_write_wakeup(struct tty_struct * tty)
252{
253	struct serport *serport = (struct serport *) tty->disc_data;
254	unsigned long flags;
255
256	spin_lock_irqsave(&serport->lock, flags);
257	if (test_bit(SERPORT_ACTIVE, &serport->flags))
258		serio_drv_write_wakeup(serport->serio);
259	spin_unlock_irqrestore(&serport->lock, flags);
260}
261
262/*
263 * The line discipline structure.
264 */
265
266static struct tty_ldisc_ops serport_ldisc = {
267	.owner =	THIS_MODULE,
268	.name =		"input",
269	.open =		serport_ldisc_open,
270	.close =	serport_ldisc_close,
271	.read =		serport_ldisc_read,
272	.ioctl =	serport_ldisc_ioctl,
273#ifdef CONFIG_COMPAT
274	.compat_ioctl =	serport_ldisc_compat_ioctl,
275#endif
276	.receive_buf =	serport_ldisc_receive,
277	.write_wakeup =	serport_ldisc_write_wakeup
278};
279
280/*
281 * The functions for insering/removing us as a module.
282 */
283
284static int __init serport_init(void)
285{
286	int retval;
287	retval = tty_register_ldisc(N_MOUSE, &serport_ldisc);
288	if (retval)
289		printk(KERN_ERR "serport.c: Error registering line discipline.\n");
290
291	return  retval;
292}
293
294static void __exit serport_exit(void)
295{
296	tty_unregister_ldisc(N_MOUSE);
297}
298
299module_init(serport_init);
300module_exit(serport_exit);
301