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
24 MODULE_AUTHOR("Vojtech Pavlik <vojtech@ucw.cz>");
25 MODULE_DESCRIPTION("Input device TTY line discipline");
26 MODULE_LICENSE("GPL");
27 MODULE_ALIAS_LDISC(N_MOUSE);
28
29 #define SERPORT_BUSY 1
30 #define SERPORT_ACTIVE 2
31 #define SERPORT_DEAD 3
32
33 struct 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
46 static int serport_serio_write(struct serio *serio, unsigned char data)
47 {
48 struct serport *serport = serio->port_data;
49 return -(serport->tty->ops->write(serport->tty, &data, 1) != 1);
50 }
51
52 static 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
65 static 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
83 static 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
109 static 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
122 static 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
136 out:
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
146 static 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
185 static 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
204 static 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
219 static struct tty_ldisc_ops 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
234 static 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
244 static void __exit serport_exit(void)
245 {
246 tty_unregister_ldisc(N_MOUSE);
247 }
248
249 module_init(serport_init);
250 module_exit(serport_exit);
251
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