tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
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linux
1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Input device TTY line discipline
4 *
5 * Copyright (c) 1999-2002 Vojtech Pavlik
6 *
7 * This is a module that converts a tty line into a much simpler
8 * 'serial io port' abstraction that the input device drivers use.
9 */
10
11
12#include <linux/uaccess.h>
13#include <linux/kernel.h>
14#include <linux/sched.h>
15#include <linux/slab.h>
16#include <linux/module.h>
17#include <linux/init.h>
18#include <linux/serio.h>
19#include <linux/tty.h>
20#include <linux/compat.h>
21
22MODULE_AUTHOR("Vojtech Pavlik <vojtech@ucw.cz>");
23MODULE_DESCRIPTION("Input device TTY line discipline");
24MODULE_LICENSE("GPL");
25MODULE_ALIAS_LDISC(N_MOUSE);
26
27#define SERPORT_BUSY 1
28#define SERPORT_ACTIVE 2
29#define SERPORT_DEAD 3
30
31struct serport {
32 struct tty_struct *tty;
33 wait_queue_head_t wait;
34 struct serio *serio;
35 struct serio_device_id id;
36 spinlock_t lock;
37 unsigned long flags;
38};
39
40/*
41 * Callback functions from the serio code.
42 */
43
44static int serport_serio_write(struct serio *serio, unsigned char data)
45{
46 struct serport *serport = serio->port_data;
47 return -(serport->tty->ops->write(serport->tty, &data, 1) != 1);
48}
49
50static int serport_serio_open(struct serio *serio)
51{
52 struct serport *serport = serio->port_data;
53 unsigned long flags;
54
55 spin_lock_irqsave(&serport->lock, flags);
56 set_bit(SERPORT_ACTIVE, &serport->flags);
57 spin_unlock_irqrestore(&serport->lock, flags);
58
59 return 0;
60}
61
62
63static void serport_serio_close(struct serio *serio)
64{
65 struct serport *serport = serio->port_data;
66 unsigned long flags;
67
68 spin_lock_irqsave(&serport->lock, flags);
69 clear_bit(SERPORT_ACTIVE, &serport->flags);
70 spin_unlock_irqrestore(&serport->lock, flags);
71}
72
73/*
74 * serport_ldisc_open() is the routine that is called upon setting our line
75 * discipline on a tty. It prepares the serio struct.
76 */
77
78static int serport_ldisc_open(struct tty_struct *tty)
79{
80 struct serport *serport;
81
82 if (!capable(CAP_SYS_ADMIN))
83 return -EPERM;
84
85 serport = kzalloc(sizeof(struct serport), GFP_KERNEL);
86 if (!serport)
87 return -ENOMEM;
88
89 serport->tty = tty;
90 spin_lock_init(&serport->lock);
91 init_waitqueue_head(&serport->wait);
92
93 tty->disc_data = serport;
94 tty->receive_room = 256;
95 set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
96
97 return 0;
98}
99
100/*
101 * serport_ldisc_close() is the opposite of serport_ldisc_open()
102 */
103
104static void serport_ldisc_close(struct tty_struct *tty)
105{
106 struct serport *serport = (struct serport *) tty->disc_data;
107
108 kfree(serport);
109}
110
111/*
112 * serport_ldisc_receive() is called by the low level tty driver when characters
113 * are ready for us. We forward the characters and flags, one by one to the
114 * 'interrupt' routine.
115 */
116
117static void serport_ldisc_receive(struct tty_struct *tty, const unsigned char *cp, char *fp, int count)
118{
119 struct serport *serport = (struct serport*) tty->disc_data;
120 unsigned long flags;
121 unsigned int ch_flags = 0;
122 int i;
123
124 spin_lock_irqsave(&serport->lock, flags);
125
126 if (!test_bit(SERPORT_ACTIVE, &serport->flags))
127 goto out;
128
129 for (i = 0; i < count; i++) {
130 if (fp) {
131 switch (fp[i]) {
132 case TTY_FRAME:
133 ch_flags = SERIO_FRAME;
134 break;
135
136 case TTY_PARITY:
137 ch_flags = SERIO_PARITY;
138 break;
139
140 default:
141 ch_flags = 0;
142 break;
143 }
144 }
145
146 serio_interrupt(serport->serio, cp[i], ch_flags);
147 }
148
149out:
150 spin_unlock_irqrestore(&serport->lock, flags);
151}
152
153/*
154 * serport_ldisc_read() just waits indefinitely if everything goes well.
155 * However, when the serio driver closes the serio port, it finishes,
156 * returning 0 characters.
157 */
158
159static ssize_t serport_ldisc_read(struct tty_struct * tty, struct file * file,
160 unsigned char *kbuf, size_t nr,
161 void **cookie, unsigned long offset)
162{
163 struct serport *serport = (struct serport*) tty->disc_data;
164 struct serio *serio;
165
166 if (test_and_set_bit(SERPORT_BUSY, &serport->flags))
167 return -EBUSY;
168
169 serport->serio = serio = kzalloc(sizeof(struct serio), GFP_KERNEL);
170 if (!serio)
171 return -ENOMEM;
172
173 strlcpy(serio->name, "Serial port", sizeof(serio->name));
174 snprintf(serio->phys, sizeof(serio->phys), "%s/serio0", tty_name(tty));
175 serio->id = serport->id;
176 serio->id.type = SERIO_RS232;
177 serio->write = serport_serio_write;
178 serio->open = serport_serio_open;
179 serio->close = serport_serio_close;
180 serio->port_data = serport;
181 serio->dev.parent = tty->dev;
182
183 serio_register_port(serport->serio);
184 printk(KERN_INFO "serio: Serial port %s\n", tty_name(tty));
185
186 wait_event_interruptible(serport->wait, test_bit(SERPORT_DEAD, &serport->flags));
187 serio_unregister_port(serport->serio);
188 serport->serio = NULL;
189
190 clear_bit(SERPORT_DEAD, &serport->flags);
191 clear_bit(SERPORT_BUSY, &serport->flags);
192
193 return 0;
194}
195
196static void serport_set_type(struct tty_struct *tty, unsigned long type)
197{
198 struct serport *serport = tty->disc_data;
199
200 serport->id.proto = type & 0x000000ff;
201 serport->id.id = (type & 0x0000ff00) >> 8;
202 serport->id.extra = (type & 0x00ff0000) >> 16;
203}
204
205/*
206 * serport_ldisc_ioctl() allows to set the port protocol, and device ID
207 */
208
209static int serport_ldisc_ioctl(struct tty_struct *tty, struct file *file,
210 unsigned int cmd, unsigned long arg)
211{
212 if (cmd == SPIOCSTYPE) {
213 unsigned long type;
214
215 if (get_user(type, (unsigned long __user *) arg))
216 return -EFAULT;
217
218 serport_set_type(tty, type);
219 return 0;
220 }
221
222 return -EINVAL;
223}
224
225#ifdef CONFIG_COMPAT
226#define COMPAT_SPIOCSTYPE _IOW('q', 0x01, compat_ulong_t)
227static int serport_ldisc_compat_ioctl(struct tty_struct *tty,
228 struct file *file,
229 unsigned int cmd, unsigned long arg)
230{
231 if (cmd == COMPAT_SPIOCSTYPE) {
232 void __user *uarg = compat_ptr(arg);
233 compat_ulong_t compat_type;
234
235 if (get_user(compat_type, (compat_ulong_t __user *)uarg))
236 return -EFAULT;
237
238 serport_set_type(tty, compat_type);
239 return 0;
240 }
241
242 return -EINVAL;
243}
244#endif
245
246static int serport_ldisc_hangup(struct tty_struct *tty)
247{
248 struct serport *serport = (struct serport *) tty->disc_data;
249 unsigned long flags;
250
251 spin_lock_irqsave(&serport->lock, flags);
252 set_bit(SERPORT_DEAD, &serport->flags);
253 spin_unlock_irqrestore(&serport->lock, flags);
254
255 wake_up_interruptible(&serport->wait);
256 return 0;
257}
258
259static void serport_ldisc_write_wakeup(struct tty_struct * tty)
260{
261 struct serport *serport = (struct serport *) tty->disc_data;
262 unsigned long flags;
263
264 spin_lock_irqsave(&serport->lock, flags);
265 if (test_bit(SERPORT_ACTIVE, &serport->flags))
266 serio_drv_write_wakeup(serport->serio);
267 spin_unlock_irqrestore(&serport->lock, flags);
268}
269
270/*
271 * The line discipline structure.
272 */
273
274static struct tty_ldisc_ops serport_ldisc = {
275 .owner = THIS_MODULE,
276 .name = "input",
277 .open = serport_ldisc_open,
278 .close = serport_ldisc_close,
279 .read = serport_ldisc_read,
280 .ioctl = serport_ldisc_ioctl,
281#ifdef CONFIG_COMPAT
282 .compat_ioctl = serport_ldisc_compat_ioctl,
283#endif
284 .receive_buf = serport_ldisc_receive,
285 .hangup = serport_ldisc_hangup,
286 .write_wakeup = serport_ldisc_write_wakeup
287};
288
289/*
290 * The functions for insering/removing us as a module.
291 */
292
293static int __init serport_init(void)
294{
295 int retval;
296 retval = tty_register_ldisc(N_MOUSE, &serport_ldisc);
297 if (retval)
298 printk(KERN_ERR "serport.c: Error registering line discipline.\n");
299
300 return retval;
301}
302
303static void __exit serport_exit(void)
304{
305 tty_unregister_ldisc(N_MOUSE);
306}
307
308module_init(serport_init);
309module_exit(serport_exit);