Linux Kernel  3.7.1
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serport.c
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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 
25 MODULE_AUTHOR("Vojtech Pavlik <[email protected]>");
26 MODULE_DESCRIPTION("Input device TTY line discipline");
27 MODULE_LICENSE("GPL");
29 
30 #define SERPORT_BUSY 1
31 #define SERPORT_ACTIVE 2
32 #define SERPORT_DEAD 3
33 
34 struct serport {
35  struct tty_struct *tty;
37  struct serio *serio;
40  unsigned long flags;
41 };
42 
43 /*
44  * Callback functions from the serio code.
45  */
46 
47 static int serport_serio_write(struct serio *serio, unsigned char data)
48 {
49  struct serport *serport = serio->port_data;
50  return -(serport->tty->ops->write(serport->tty, &data, 1) != 1);
51 }
52 
53 static int serport_serio_open(struct serio *serio)
54 {
55  struct serport *serport = serio->port_data;
56  unsigned long flags;
57 
58  spin_lock_irqsave(&serport->lock, flags);
59  set_bit(SERPORT_ACTIVE, &serport->flags);
60  spin_unlock_irqrestore(&serport->lock, flags);
61 
62  return 0;
63 }
64 
65 
66 static void serport_serio_close(struct serio *serio)
67 {
68  struct serport *serport = serio->port_data;
69  unsigned long flags;
70 
71  spin_lock_irqsave(&serport->lock, flags);
72  clear_bit(SERPORT_ACTIVE, &serport->flags);
73  set_bit(SERPORT_DEAD, &serport->flags);
74  spin_unlock_irqrestore(&serport->lock, flags);
75 
76  wake_up_interruptible(&serport->wait);
77 }
78 
79 /*
80  * serport_ldisc_open() is the routine that is called upon setting our line
81  * discipline on a tty. It prepares the serio struct.
82  */
83 
84 static int serport_ldisc_open(struct tty_struct *tty)
85 {
86  struct serport *serport;
87 
88  if (!capable(CAP_SYS_ADMIN))
89  return -EPERM;
90 
91  serport = kzalloc(sizeof(struct serport), GFP_KERNEL);
92  if (!serport)
93  return -ENOMEM;
94 
95  serport->tty = tty;
96  spin_lock_init(&serport->lock);
97  init_waitqueue_head(&serport->wait);
98 
99  tty->disc_data = serport;
100  tty->receive_room = 256;
102 
103  return 0;
104 }
105 
106 /*
107  * serport_ldisc_close() is the opposite of serport_ldisc_open()
108  */
109 
110 static void serport_ldisc_close(struct tty_struct *tty)
111 {
112  struct serport *serport = (struct serport *) tty->disc_data;
113 
114  kfree(serport);
115 }
116 
117 /*
118  * serport_ldisc_receive() is called by the low level tty driver when characters
119  * are ready for us. We forward the characters and flags, one by one to the
120  * 'interrupt' routine.
121  */
122 
123 static void serport_ldisc_receive(struct tty_struct *tty, const unsigned char *cp, char *fp, int count)
124 {
125  struct serport *serport = (struct serport*) tty->disc_data;
126  unsigned long flags;
127  unsigned int ch_flags;
128  int i;
129 
130  spin_lock_irqsave(&serport->lock, flags);
131 
132  if (!test_bit(SERPORT_ACTIVE, &serport->flags))
133  goto out;
134 
135  for (i = 0; i < count; i++) {
136  switch (fp[i]) {
137  case TTY_FRAME:
138  ch_flags = SERIO_FRAME;
139  break;
140 
141  case TTY_PARITY:
142  ch_flags = SERIO_PARITY;
143  break;
144 
145  default:
146  ch_flags = 0;
147  break;
148  }
149 
150  serio_interrupt(serport->serio, cp[i], ch_flags);
151  }
152 
153 out:
154  spin_unlock_irqrestore(&serport->lock, flags);
155 }
156 
157 /*
158  * serport_ldisc_read() just waits indefinitely if everything goes well.
159  * However, when the serio driver closes the serio port, it finishes,
160  * returning 0 characters.
161  */
162 
163 static ssize_t serport_ldisc_read(struct tty_struct * tty, struct file * file, unsigned char __user * buf, size_t nr)
164 {
165  struct serport *serport = (struct serport*) tty->disc_data;
166  struct serio *serio;
167  char name[64];
168 
169  if (test_and_set_bit(SERPORT_BUSY, &serport->flags))
170  return -EBUSY;
171 
172  serport->serio = serio = kzalloc(sizeof(struct serio), GFP_KERNEL);
173  if (!serio)
174  return -ENOMEM;
175 
176  strlcpy(serio->name, "Serial port", sizeof(serio->name));
177  snprintf(serio->phys, sizeof(serio->phys), "%s/serio0", tty_name(tty, name));
178  serio->id = serport->id;
179  serio->id.type = SERIO_RS232;
180  serio->write = serport_serio_write;
181  serio->open = serport_serio_open;
182  serio->close = serport_serio_close;
183  serio->port_data = serport;
184  serio->dev.parent = tty->dev;
185 
186  serio_register_port(serport->serio);
187  printk(KERN_INFO "serio: Serial port %s\n", tty_name(tty, name));
188 
190  serio_unregister_port(serport->serio);
191  serport->serio = NULL;
192 
193  clear_bit(SERPORT_DEAD, &serport->flags);
194  clear_bit(SERPORT_BUSY, &serport->flags);
195 
196  return 0;
197 }
198 
199 /*
200  * serport_ldisc_ioctl() allows to set the port protocol, and device ID
201  */
202 
203 static int serport_ldisc_ioctl(struct tty_struct * tty, struct file * file, unsigned int cmd, unsigned long arg)
204 {
205  struct serport *serport = (struct serport*) tty->disc_data;
206  unsigned long type;
207 
208  if (cmd == SPIOCSTYPE) {
209  if (get_user(type, (unsigned long __user *) arg))
210  return -EFAULT;
211 
212  serport->id.proto = type & 0x000000ff;
213  serport->id.id = (type & 0x0000ff00) >> 8;
214  serport->id.extra = (type & 0x00ff0000) >> 16;
215 
216  return 0;
217  }
218 
219  return -EINVAL;
220 }
221 
222 static void serport_ldisc_write_wakeup(struct tty_struct * tty)
223 {
224  struct serport *serport = (struct serport *) tty->disc_data;
225  unsigned long flags;
226 
227  spin_lock_irqsave(&serport->lock, flags);
228  if (test_bit(SERPORT_ACTIVE, &serport->flags))
229  serio_drv_write_wakeup(serport->serio);
230  spin_unlock_irqrestore(&serport->lock, flags);
231 }
232 
233 /*
234  * The line discipline structure.
235  */
236 
237 static struct tty_ldisc_ops serport_ldisc = {
238  .owner = THIS_MODULE,
239  .name = "input",
240  .open = serport_ldisc_open,
241  .close = serport_ldisc_close,
242  .read = serport_ldisc_read,
243  .ioctl = serport_ldisc_ioctl,
244  .receive_buf = serport_ldisc_receive,
245  .write_wakeup = serport_ldisc_write_wakeup
246 };
247 
248 /*
249  * The functions for insering/removing us as a module.
250  */
251 
252 static int __init serport_init(void)
253 {
254  int retval;
255  retval = tty_register_ldisc(N_MOUSE, &serport_ldisc);
256  if (retval)
257  printk(KERN_ERR "serport.c: Error registering line discipline.\n");
258 
259  return retval;
260 }
261 
262 static void __exit serport_exit(void)
263 {
265 }
266 
267 module_init(serport_init);
268 module_exit(serport_exit);