Commit | Line | Data |
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24b4b67d SP |
1 | /* |
2 | * linux/drivers/char/ttyprintk.c | |
3 | * | |
4 | * Copyright (C) 2010 Samo Pogacnik | |
5 | * | |
6 | * This program is free software; you can redistribute it and/or modify | |
7 | * it under the smems of the GNU General Public License as published by | |
8 | * the Free Software Foundation; version 2 of the License. | |
9 | */ | |
10 | ||
11 | /* | |
12 | * This pseudo device allows user to make printk messages. It is possible | |
13 | * to store "console" messages inline with kernel messages for better analyses | |
14 | * of the boot process, for example. | |
15 | */ | |
16 | ||
17 | #include <linux/device.h> | |
18 | #include <linux/serial.h> | |
19 | #include <linux/tty.h> | |
b24313a8 | 20 | #include <linux/module.h> |
24b4b67d SP |
21 | |
22 | struct ttyprintk_port { | |
23 | struct tty_port port; | |
24 | struct mutex port_write_mutex; | |
25 | }; | |
26 | ||
27 | static struct ttyprintk_port tpk_port; | |
28 | ||
29 | /* | |
30 | * Our simple preformatting supports transparent output of (time-stamped) | |
31 | * printk messages (also suitable for logging service): | |
32 | * - any cr is replaced by nl | |
33 | * - adds a ttyprintk source tag in front of each line | |
0b3191d4 JP |
34 | * - too long message is fragmented, with '\'nl between fragments |
35 | * - TPK_STR_SIZE isn't really the write_room limiting factor, because | |
24b4b67d SP |
36 | * it is emptied on the fly during preformatting. |
37 | */ | |
38 | #define TPK_STR_SIZE 508 /* should be bigger then max expected line length */ | |
39 | #define TPK_MAX_ROOM 4096 /* we could assume 4K for instance */ | |
24b4b67d SP |
40 | static int tpk_curr; |
41 | ||
0b3191d4 JP |
42 | static char tpk_buffer[TPK_STR_SIZE + 4]; |
43 | ||
44 | static void tpk_flush(void) | |
45 | { | |
46 | if (tpk_curr > 0) { | |
47 | tpk_buffer[tpk_curr] = '\0'; | |
48 | pr_info("[U] %s\n", tpk_buffer); | |
49 | tpk_curr = 0; | |
50 | } | |
51 | } | |
52 | ||
24b4b67d SP |
53 | static int tpk_printk(const unsigned char *buf, int count) |
54 | { | |
24b4b67d SP |
55 | int i = tpk_curr; |
56 | ||
57 | if (buf == NULL) { | |
0b3191d4 | 58 | tpk_flush(); |
24b4b67d SP |
59 | return i; |
60 | } | |
61 | ||
62 | for (i = 0; i < count; i++) { | |
0b3191d4 | 63 | if (tpk_curr >= TPK_STR_SIZE) { |
24b4b67d | 64 | /* end of tmp buffer reached: cut the message in two */ |
0b3191d4 JP |
65 | tpk_buffer[tpk_curr++] = '\\'; |
66 | tpk_flush(); | |
67 | } | |
68 | ||
69 | switch (buf[i]) { | |
70 | case '\r': | |
71 | tpk_flush(); | |
72 | if ((i + 1) < count && buf[i + 1] == '\n') | |
73 | i++; | |
74 | break; | |
75 | case '\n': | |
76 | tpk_flush(); | |
77 | break; | |
78 | default: | |
79 | tpk_buffer[tpk_curr++] = buf[i]; | |
80 | break; | |
24b4b67d SP |
81 | } |
82 | } | |
83 | ||
84 | return count; | |
85 | } | |
86 | ||
87 | /* | |
88 | * TTY operations open function. | |
89 | */ | |
90 | static int tpk_open(struct tty_struct *tty, struct file *filp) | |
91 | { | |
92 | tty->driver_data = &tpk_port; | |
93 | ||
94 | return tty_port_open(&tpk_port.port, tty, filp); | |
95 | } | |
96 | ||
97 | /* | |
98 | * TTY operations close function. | |
99 | */ | |
100 | static void tpk_close(struct tty_struct *tty, struct file *filp) | |
101 | { | |
102 | struct ttyprintk_port *tpkp = tty->driver_data; | |
103 | ||
104 | mutex_lock(&tpkp->port_write_mutex); | |
105 | /* flush tpk_printk buffer */ | |
106 | tpk_printk(NULL, 0); | |
107 | mutex_unlock(&tpkp->port_write_mutex); | |
108 | ||
109 | tty_port_close(&tpkp->port, tty, filp); | |
110 | } | |
111 | ||
112 | /* | |
113 | * TTY operations write function. | |
114 | */ | |
115 | static int tpk_write(struct tty_struct *tty, | |
116 | const unsigned char *buf, int count) | |
117 | { | |
118 | struct ttyprintk_port *tpkp = tty->driver_data; | |
119 | int ret; | |
120 | ||
121 | ||
122 | /* exclusive use of tpk_printk within this tty */ | |
123 | mutex_lock(&tpkp->port_write_mutex); | |
124 | ret = tpk_printk(buf, count); | |
125 | mutex_unlock(&tpkp->port_write_mutex); | |
126 | ||
127 | return ret; | |
128 | } | |
129 | ||
130 | /* | |
131 | * TTY operations write_room function. | |
132 | */ | |
133 | static int tpk_write_room(struct tty_struct *tty) | |
134 | { | |
135 | return TPK_MAX_ROOM; | |
136 | } | |
137 | ||
138 | /* | |
139 | * TTY operations ioctl function. | |
140 | */ | |
6caa76b7 | 141 | static int tpk_ioctl(struct tty_struct *tty, |
24b4b67d SP |
142 | unsigned int cmd, unsigned long arg) |
143 | { | |
144 | struct ttyprintk_port *tpkp = tty->driver_data; | |
145 | ||
146 | if (!tpkp) | |
147 | return -EINVAL; | |
148 | ||
149 | switch (cmd) { | |
150 | /* Stop TIOCCONS */ | |
151 | case TIOCCONS: | |
152 | return -EOPNOTSUPP; | |
153 | default: | |
154 | return -ENOIOCTLCMD; | |
155 | } | |
156 | return 0; | |
157 | } | |
158 | ||
159 | static const struct tty_operations ttyprintk_ops = { | |
160 | .open = tpk_open, | |
161 | .close = tpk_close, | |
162 | .write = tpk_write, | |
163 | .write_room = tpk_write_room, | |
164 | .ioctl = tpk_ioctl, | |
165 | }; | |
166 | ||
9b95d95d | 167 | static const struct tty_port_operations null_ops = { }; |
24b4b67d SP |
168 | |
169 | static struct tty_driver *ttyprintk_driver; | |
170 | ||
171 | static int __init ttyprintk_init(void) | |
172 | { | |
173 | int ret = -ENOMEM; | |
24b4b67d | 174 | |
536a3440 JS |
175 | mutex_init(&tpk_port.port_write_mutex); |
176 | ||
0019b408 JS |
177 | ttyprintk_driver = tty_alloc_driver(1, |
178 | TTY_DRIVER_RESET_TERMIOS | | |
179 | TTY_DRIVER_REAL_RAW | | |
180 | TTY_DRIVER_UNNUMBERED_NODE); | |
c3a6344a DC |
181 | if (IS_ERR(ttyprintk_driver)) |
182 | return PTR_ERR(ttyprintk_driver); | |
24b4b67d | 183 | |
191c5f10 | 184 | tty_port_init(&tpk_port.port); |
b5325a02 | 185 | tpk_port.port.ops = &null_ops; |
191c5f10 | 186 | |
24b4b67d SP |
187 | ttyprintk_driver->driver_name = "ttyprintk"; |
188 | ttyprintk_driver->name = "ttyprintk"; | |
189 | ttyprintk_driver->major = TTYAUX_MAJOR; | |
190 | ttyprintk_driver->minor_start = 3; | |
24b4b67d SP |
191 | ttyprintk_driver->type = TTY_DRIVER_TYPE_CONSOLE; |
192 | ttyprintk_driver->init_termios = tty_std_termios; | |
193 | ttyprintk_driver->init_termios.c_oflag = OPOST | OCRNL | ONOCR | ONLRET; | |
24b4b67d | 194 | tty_set_operations(ttyprintk_driver, &ttyprintk_ops); |
b19e2ca7 | 195 | tty_port_link_device(&tpk_port.port, ttyprintk_driver, 0); |
24b4b67d SP |
196 | |
197 | ret = tty_register_driver(ttyprintk_driver); | |
198 | if (ret < 0) { | |
199 | printk(KERN_ERR "Couldn't register ttyprintk driver\n"); | |
200 | goto error; | |
201 | } | |
202 | ||
24b4b67d SP |
203 | return 0; |
204 | ||
205 | error: | |
206 | put_tty_driver(ttyprintk_driver); | |
191c5f10 | 207 | tty_port_destroy(&tpk_port.port); |
24b4b67d SP |
208 | return ret; |
209 | } | |
b24313a8 TI |
210 | |
211 | static void __exit ttyprintk_exit(void) | |
212 | { | |
213 | tty_unregister_driver(ttyprintk_driver); | |
214 | put_tty_driver(ttyprintk_driver); | |
215 | tty_port_destroy(&tpk_port.port); | |
216 | } | |
217 | ||
db50d2f6 | 218 | device_initcall(ttyprintk_init); |
b24313a8 TI |
219 | module_exit(ttyprintk_exit); |
220 | ||
221 | MODULE_LICENSE("GPL"); |