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 | |
22 | MODULE_AUTHOR("Vojtech Pavlik <vojtech@ucw.cz>" ); |
23 | MODULE_DESCRIPTION("Input device TTY line discipline" ); |
24 | MODULE_LICENSE("GPL" ); |
25 | MODULE_ALIAS_LDISC(N_MOUSE); |
26 | |
27 | #define SERPORT_BUSY 1 |
28 | #define SERPORT_ACTIVE 2 |
29 | #define SERPORT_DEAD 3 |
30 | |
31 | struct 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 | |
44 | static 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 | |
50 | static 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, addr: &serport->flags); |
57 | spin_unlock_irqrestore(lock: &serport->lock, flags); |
58 | |
59 | return 0; |
60 | } |
61 | |
62 | |
63 | static 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, addr: &serport->flags); |
70 | spin_unlock_irqrestore(lock: &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 | |
78 | static 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(size: 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, addr: &tty->flags); |
96 | |
97 | return 0; |
98 | } |
99 | |
100 | /* |
101 | * serport_ldisc_close() is the opposite of serport_ldisc_open() |
102 | */ |
103 | |
104 | static void serport_ldisc_close(struct tty_struct *tty) |
105 | { |
106 | struct serport *serport = tty->disc_data; |
107 | |
108 | kfree(objp: 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 | |
117 | static void serport_ldisc_receive(struct tty_struct *tty, const u8 *cp, |
118 | const u8 *fp, size_t count) |
119 | { |
120 | struct serport *serport = tty->disc_data; |
121 | unsigned long flags; |
122 | unsigned int ch_flags = 0; |
123 | int i; |
124 | |
125 | spin_lock_irqsave(&serport->lock, flags); |
126 | |
127 | if (!test_bit(SERPORT_ACTIVE, &serport->flags)) |
128 | goto out; |
129 | |
130 | for (i = 0; i < count; i++) { |
131 | if (fp) { |
132 | switch (fp[i]) { |
133 | case TTY_FRAME: |
134 | ch_flags = SERIO_FRAME; |
135 | break; |
136 | |
137 | case TTY_PARITY: |
138 | ch_flags = SERIO_PARITY; |
139 | break; |
140 | |
141 | default: |
142 | ch_flags = 0; |
143 | break; |
144 | } |
145 | } |
146 | |
147 | serio_interrupt(serio: serport->serio, data: cp[i], flags: ch_flags); |
148 | } |
149 | |
150 | out: |
151 | spin_unlock_irqrestore(lock: &serport->lock, flags); |
152 | } |
153 | |
154 | /* |
155 | * serport_ldisc_read() just waits indefinitely if everything goes well. |
156 | * However, when the serio driver closes the serio port, it finishes, |
157 | * returning 0 characters. |
158 | */ |
159 | |
160 | static ssize_t serport_ldisc_read(struct tty_struct * tty, struct file * file, |
161 | u8 *kbuf, size_t nr, void **cookie, |
162 | unsigned long offset) |
163 | { |
164 | struct serport *serport = tty->disc_data; |
165 | struct serio *serio; |
166 | |
167 | if (test_and_set_bit(SERPORT_BUSY, addr: &serport->flags)) |
168 | return -EBUSY; |
169 | |
170 | serport->serio = serio = kzalloc(size: sizeof(struct serio), GFP_KERNEL); |
171 | if (!serio) |
172 | return -ENOMEM; |
173 | |
174 | strscpy(p: serio->name, q: "Serial port" , size: sizeof(serio->name)); |
175 | snprintf(buf: serio->phys, size: sizeof(serio->phys), fmt: "%s/serio0" , tty_name(tty)); |
176 | serio->id = serport->id; |
177 | serio->id.type = SERIO_RS232; |
178 | serio->write = serport_serio_write; |
179 | serio->open = serport_serio_open; |
180 | serio->close = serport_serio_close; |
181 | serio->port_data = serport; |
182 | serio->dev.parent = tty->dev; |
183 | |
184 | serio_register_port(serport->serio); |
185 | printk(KERN_INFO "serio: Serial port %s\n" , tty_name(tty)); |
186 | |
187 | wait_event_interruptible(serport->wait, test_bit(SERPORT_DEAD, &serport->flags)); |
188 | serio_unregister_port(serio: serport->serio); |
189 | serport->serio = NULL; |
190 | |
191 | clear_bit(SERPORT_DEAD, addr: &serport->flags); |
192 | clear_bit(SERPORT_BUSY, addr: &serport->flags); |
193 | |
194 | return 0; |
195 | } |
196 | |
197 | static void serport_set_type(struct tty_struct *tty, unsigned long type) |
198 | { |
199 | struct serport *serport = tty->disc_data; |
200 | |
201 | serport->id.proto = type & 0x000000ff; |
202 | serport->id.id = (type & 0x0000ff00) >> 8; |
203 | serport->id.extra = (type & 0x00ff0000) >> 16; |
204 | } |
205 | |
206 | /* |
207 | * serport_ldisc_ioctl() allows to set the port protocol, and device ID |
208 | */ |
209 | |
210 | static int serport_ldisc_ioctl(struct tty_struct *tty, unsigned int cmd, |
211 | unsigned long arg) |
212 | { |
213 | if (cmd == SPIOCSTYPE) { |
214 | unsigned long type; |
215 | |
216 | if (get_user(type, (unsigned long __user *) arg)) |
217 | return -EFAULT; |
218 | |
219 | serport_set_type(tty, type); |
220 | return 0; |
221 | } |
222 | |
223 | return -EINVAL; |
224 | } |
225 | |
226 | #ifdef CONFIG_COMPAT |
227 | #define COMPAT_SPIOCSTYPE _IOW('q', 0x01, compat_ulong_t) |
228 | static int serport_ldisc_compat_ioctl(struct tty_struct *tty, |
229 | unsigned int cmd, unsigned long arg) |
230 | { |
231 | if (cmd == COMPAT_SPIOCSTYPE) { |
232 | void __user *uarg = compat_ptr(uptr: 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, type: compat_type); |
239 | return 0; |
240 | } |
241 | |
242 | return -EINVAL; |
243 | } |
244 | #endif |
245 | |
246 | static void serport_ldisc_hangup(struct tty_struct *tty) |
247 | { |
248 | struct serport *serport = tty->disc_data; |
249 | unsigned long flags; |
250 | |
251 | spin_lock_irqsave(&serport->lock, flags); |
252 | set_bit(SERPORT_DEAD, addr: &serport->flags); |
253 | spin_unlock_irqrestore(lock: &serport->lock, flags); |
254 | |
255 | wake_up_interruptible(&serport->wait); |
256 | } |
257 | |
258 | static void serport_ldisc_write_wakeup(struct tty_struct * tty) |
259 | { |
260 | struct serport *serport = tty->disc_data; |
261 | unsigned long flags; |
262 | |
263 | spin_lock_irqsave(&serport->lock, flags); |
264 | if (test_bit(SERPORT_ACTIVE, &serport->flags)) |
265 | serio_drv_write_wakeup(serio: serport->serio); |
266 | spin_unlock_irqrestore(lock: &serport->lock, flags); |
267 | } |
268 | |
269 | /* |
270 | * The line discipline structure. |
271 | */ |
272 | |
273 | static struct tty_ldisc_ops serport_ldisc = { |
274 | .owner = THIS_MODULE, |
275 | .num = N_MOUSE, |
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 | |
293 | static int __init serport_init(void) |
294 | { |
295 | int retval; |
296 | retval = tty_register_ldisc(new_ldisc: &serport_ldisc); |
297 | if (retval) |
298 | printk(KERN_ERR "serport.c: Error registering line discipline.\n" ); |
299 | |
300 | return retval; |
301 | } |
302 | |
303 | static void __exit serport_exit(void) |
304 | { |
305 | tty_unregister_ldisc(ldisc: &serport_ldisc); |
306 | } |
307 | |
308 | module_init(serport_init); |
309 | module_exit(serport_exit); |
310 | |