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/slab.h>
19#include <linux/module.h>
20#include <linux/init.h>
21#include <linux/serio.h>
22#include <linux/tty.h>
23
24MODULE_AUTHOR("Vojtech Pavlik <vojtech@ucw.cz>");
25MODULE_DESCRIPTION("Input device TTY line discipline");
26MODULE_LICENSE("GPL");
27MODULE_ALIAS_LDISC(N_MOUSE);
28
29#define SERPORT_BUSY	1
30#define SERPORT_ACTIVE	2
31#define SERPORT_DEAD	3
32
33struct serport {
34	struct tty_struct *tty;
35	wait_queue_head_t wait;
36	struct serio *serio;
37	struct serio_device_id id;
38	spinlock_t lock;
39	unsigned long flags;
40};
41
42/*
43 * Callback functions from the serio code.
44 */
45
46static int serport_serio_write(struct serio *serio, unsigned char data)
47{
48	struct serport *serport = serio->port_data;
49	return -(serport->tty->driver->write(serport->tty, &data, 1) != 1);
50}
51
52static int serport_serio_open(struct serio *serio)
53{
54	struct serport *serport = serio->port_data;
55	unsigned long flags;
56
57	spin_lock_irqsave(&serport->lock, flags);
58	set_bit(SERPORT_ACTIVE, &serport->flags);
59	spin_unlock_irqrestore(&serport->lock, flags);
60
61	return 0;
62}
63
64
65static void serport_serio_close(struct serio *serio)
66{
67	struct serport *serport = serio->port_data;
68	unsigned long flags;
69
70	spin_lock_irqsave(&serport->lock, flags);
71	clear_bit(SERPORT_ACTIVE, &serport->flags);
72	set_bit(SERPORT_DEAD, &serport->flags);
73	spin_unlock_irqrestore(&serport->lock, flags);
74
75	wake_up_interruptible(&serport->wait);
76}
77
78/*
79 * serport_ldisc_open() is the routine that is called upon setting our line
80 * discipline on a tty. It prepares the serio struct.
81 */
82
83static int serport_ldisc_open(struct tty_struct *tty)
84{
85	struct serport *serport;
86
87	if (!capable(CAP_SYS_ADMIN))
88		return -EPERM;
89
90	serport = kzalloc(sizeof(struct serport), GFP_KERNEL);
91	if (!serport)
92		return -ENOMEM;
93
94	serport->tty = tty;
95	spin_lock_init(&serport->lock);
96	init_waitqueue_head(&serport->wait);
97
98	tty->disc_data = serport;
99	tty->receive_room = 256;
100	set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
101
102	return 0;
103}
104
105/*
106 * serport_ldisc_close() is the opposite of serport_ldisc_open()
107 */
108
109static void serport_ldisc_close(struct tty_struct *tty)
110{
111	struct serport *serport = (struct serport *) tty->disc_data;
112
113	kfree(serport);
114}
115
116/*
117 * serport_ldisc_receive() is called by the low level tty driver when characters
118 * are ready for us. We forward the characters, one by one to the 'interrupt'
119 * routine.
120 */
121
122static void serport_ldisc_receive(struct tty_struct *tty, const unsigned char *cp, char *fp, int count)
123{
124	struct serport *serport = (struct serport*) tty->disc_data;
125	unsigned long flags;
126	int i;
127
128	spin_lock_irqsave(&serport->lock, flags);
129
130	if (!test_bit(SERPORT_ACTIVE, &serport->flags))
131		goto out;
132
133	for (i = 0; i < count; i++)
134		serio_interrupt(serport->serio, cp[i], 0);
135
136out:
137	spin_unlock_irqrestore(&serport->lock, flags);
138}
139
140/*
141 * serport_ldisc_read() just waits indefinitely if everything goes well.
142 * However, when the serio driver closes the serio port, it finishes,
143 * returning 0 characters.
144 */
145
146static ssize_t serport_ldisc_read(struct tty_struct * tty, struct file * file, unsigned char __user * buf, size_t nr)
147{
148	struct serport *serport = (struct serport*) tty->disc_data;
149	struct serio *serio;
150	char name[64];
151
152	if (test_and_set_bit(SERPORT_BUSY, &serport->flags))
153		return -EBUSY;
154
155	serport->serio = serio = kzalloc(sizeof(struct serio), GFP_KERNEL);
156	if (!serio)
157		return -ENOMEM;
158
159	strlcpy(serio->name, "Serial port", sizeof(serio->name));
160	snprintf(serio->phys, sizeof(serio->phys), "%s/serio0", tty_name(tty, name));
161	serio->id = serport->id;
162	serio->id.type = SERIO_RS232;
163	serio->write = serport_serio_write;
164	serio->open = serport_serio_open;
165	serio->close = serport_serio_close;
166	serio->port_data = serport;
167
168	serio_register_port(serport->serio);
169	printk(KERN_INFO "serio: Serial port %s\n", tty_name(tty, name));
170
171	wait_event_interruptible(serport->wait, test_bit(SERPORT_DEAD, &serport->flags));
172	serio_unregister_port(serport->serio);
173	serport->serio = NULL;
174
175	clear_bit(SERPORT_DEAD, &serport->flags);
176	clear_bit(SERPORT_BUSY, &serport->flags);
177
178	return 0;
179}
180
181/*
182 * serport_ldisc_ioctl() allows to set the port protocol, and device ID
183 */
184
185static int serport_ldisc_ioctl(struct tty_struct * tty, struct file * file, unsigned int cmd, unsigned long arg)
186{
187	struct serport *serport = (struct serport*) tty->disc_data;
188	unsigned long type;
189
190	if (cmd == SPIOCSTYPE) {
191		if (get_user(type, (unsigned long __user *) arg))
192			return -EFAULT;
193
194		serport->id.proto = type & 0x000000ff;
195		serport->id.id	  = (type & 0x0000ff00) >> 8;
196		serport->id.extra = (type & 0x00ff0000) >> 16;
197
198		return 0;
199	}
200
201	return -EINVAL;
202}
203
204static void serport_ldisc_write_wakeup(struct tty_struct * tty)
205{
206	struct serport *serport = (struct serport *) tty->disc_data;
207	unsigned long flags;
208
209	spin_lock_irqsave(&serport->lock, flags);
210	if (test_bit(SERPORT_ACTIVE, &serport->flags))
211		serio_drv_write_wakeup(serport->serio);
212	spin_unlock_irqrestore(&serport->lock, flags);
213}
214
215/*
216 * The line discipline structure.
217 */
218
219static struct tty_ldisc serport_ldisc = {
220	.owner =	THIS_MODULE,
221	.name =		"input",
222	.open =		serport_ldisc_open,
223	.close =	serport_ldisc_close,
224	.read =		serport_ldisc_read,
225	.ioctl =	serport_ldisc_ioctl,
226	.receive_buf =	serport_ldisc_receive,
227	.write_wakeup =	serport_ldisc_write_wakeup
228};
229
230/*
231 * The functions for insering/removing us as a module.
232 */
233
234static int __init serport_init(void)
235{
236	int retval;
237	retval = tty_register_ldisc(N_MOUSE, &serport_ldisc);
238	if (retval)
239		printk(KERN_ERR "serport.c: Error registering line discipline.\n");
240
241	return  retval;
242}
243
244static void __exit serport_exit(void)
245{
246	tty_unregister_ldisc(N_MOUSE);
247}
248
249module_init(serport_init);
250module_exit(serport_exit);
251