Commit | Line | Data |
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a6377d90 | 1 | // SPDX-License-Identifier: GPL-2.0-only |
24b4b67d SP |
2 | /* |
3 | * linux/drivers/char/ttyprintk.c | |
4 | * | |
5 | * Copyright (C) 2010 Samo Pogacnik | |
24b4b67d SP |
6 | */ |
7 | ||
8 | /* | |
9 | * This pseudo device allows user to make printk messages. It is possible | |
10 | * to store "console" messages inline with kernel messages for better analyses | |
11 | * of the boot process, for example. | |
12 | */ | |
13 | ||
7ea4aa70 | 14 | #include <linux/console.h> |
24b4b67d SP |
15 | #include <linux/device.h> |
16 | #include <linux/serial.h> | |
17 | #include <linux/tty.h> | |
b24313a8 | 18 | #include <linux/module.h> |
9a655c77 | 19 | #include <linux/spinlock.h> |
24b4b67d SP |
20 | |
21 | struct ttyprintk_port { | |
22 | struct tty_port port; | |
9a655c77 | 23 | spinlock_t spinlock; |
24b4b67d SP |
24 | }; |
25 | ||
26 | static struct ttyprintk_port tpk_port; | |
27 | ||
28 | /* | |
29 | * Our simple preformatting supports transparent output of (time-stamped) | |
30 | * printk messages (also suitable for logging service): | |
31 | * - any cr is replaced by nl | |
32 | * - adds a ttyprintk source tag in front of each line | |
0b3191d4 JP |
33 | * - too long message is fragmented, with '\'nl between fragments |
34 | * - TPK_STR_SIZE isn't really the write_room limiting factor, because | |
24b4b67d SP |
35 | * it is emptied on the fly during preformatting. |
36 | */ | |
37 | #define TPK_STR_SIZE 508 /* should be bigger then max expected line length */ | |
38 | #define TPK_MAX_ROOM 4096 /* we could assume 4K for instance */ | |
acef6660 PK |
39 | #define TPK_PREFIX KERN_SOH __stringify(CONFIG_TTY_PRINTK_LEVEL) |
40 | ||
24b4b67d SP |
41 | static int tpk_curr; |
42 | ||
18977909 | 43 | static u8 tpk_buffer[TPK_STR_SIZE + 4]; |
0b3191d4 JP |
44 | |
45 | static void tpk_flush(void) | |
46 | { | |
47 | if (tpk_curr > 0) { | |
48 | tpk_buffer[tpk_curr] = '\0'; | |
acef6660 | 49 | printk(TPK_PREFIX "[U] %s\n", tpk_buffer); |
0b3191d4 JP |
50 | tpk_curr = 0; |
51 | } | |
52 | } | |
53 | ||
18977909 | 54 | static int tpk_printk(const u8 *buf, size_t count) |
24b4b67d | 55 | { |
18977909 | 56 | size_t i; |
24b4b67d | 57 | |
24b4b67d | 58 | for (i = 0; i < count; i++) { |
0b3191d4 | 59 | if (tpk_curr >= TPK_STR_SIZE) { |
24b4b67d | 60 | /* end of tmp buffer reached: cut the message in two */ |
0b3191d4 JP |
61 | tpk_buffer[tpk_curr++] = '\\'; |
62 | tpk_flush(); | |
63 | } | |
64 | ||
65 | switch (buf[i]) { | |
66 | case '\r': | |
67 | tpk_flush(); | |
68 | if ((i + 1) < count && buf[i + 1] == '\n') | |
69 | i++; | |
70 | break; | |
71 | case '\n': | |
72 | tpk_flush(); | |
73 | break; | |
74 | default: | |
75 | tpk_buffer[tpk_curr++] = buf[i]; | |
76 | break; | |
24b4b67d SP |
77 | } |
78 | } | |
79 | ||
80 | return count; | |
81 | } | |
82 | ||
83 | /* | |
84 | * TTY operations open function. | |
85 | */ | |
86 | static int tpk_open(struct tty_struct *tty, struct file *filp) | |
87 | { | |
88 | tty->driver_data = &tpk_port; | |
89 | ||
90 | return tty_port_open(&tpk_port.port, tty, filp); | |
91 | } | |
92 | ||
93 | /* | |
94 | * TTY operations close function. | |
95 | */ | |
96 | static void tpk_close(struct tty_struct *tty, struct file *filp) | |
97 | { | |
98 | struct ttyprintk_port *tpkp = tty->driver_data; | |
24b4b67d SP |
99 | |
100 | tty_port_close(&tpkp->port, tty, filp); | |
101 | } | |
102 | ||
103 | /* | |
104 | * TTY operations write function. | |
105 | */ | |
95713967 | 106 | static ssize_t tpk_write(struct tty_struct *tty, const u8 *buf, size_t count) |
24b4b67d SP |
107 | { |
108 | struct ttyprintk_port *tpkp = tty->driver_data; | |
9a655c77 | 109 | unsigned long flags; |
24b4b67d SP |
110 | int ret; |
111 | ||
24b4b67d | 112 | /* exclusive use of tpk_printk within this tty */ |
9a655c77 | 113 | spin_lock_irqsave(&tpkp->spinlock, flags); |
24b4b67d | 114 | ret = tpk_printk(buf, count); |
9a655c77 | 115 | spin_unlock_irqrestore(&tpkp->spinlock, flags); |
24b4b67d SP |
116 | |
117 | return ret; | |
118 | } | |
119 | ||
120 | /* | |
121 | * TTY operations write_room function. | |
122 | */ | |
03b3b1a2 | 123 | static unsigned int tpk_write_room(struct tty_struct *tty) |
24b4b67d SP |
124 | { |
125 | return TPK_MAX_ROOM; | |
126 | } | |
127 | ||
c0070e1e TH |
128 | /* |
129 | * TTY operations hangup function. | |
130 | */ | |
131 | static void tpk_hangup(struct tty_struct *tty) | |
132 | { | |
133 | struct ttyprintk_port *tpkp = tty->driver_data; | |
134 | ||
135 | tty_port_hangup(&tpkp->port); | |
136 | } | |
137 | ||
bf3d6ab9 SP |
138 | /* |
139 | * TTY port operations shutdown function. | |
140 | */ | |
141 | static void tpk_port_shutdown(struct tty_port *tport) | |
142 | { | |
143 | struct ttyprintk_port *tpkp = | |
144 | container_of(tport, struct ttyprintk_port, port); | |
145 | unsigned long flags; | |
146 | ||
147 | spin_lock_irqsave(&tpkp->spinlock, flags); | |
148 | tpk_flush(); | |
149 | spin_unlock_irqrestore(&tpkp->spinlock, flags); | |
150 | } | |
151 | ||
24b4b67d SP |
152 | static const struct tty_operations ttyprintk_ops = { |
153 | .open = tpk_open, | |
154 | .close = tpk_close, | |
155 | .write = tpk_write, | |
156 | .write_room = tpk_write_room, | |
c0070e1e | 157 | .hangup = tpk_hangup, |
24b4b67d SP |
158 | }; |
159 | ||
bf3d6ab9 SP |
160 | static const struct tty_port_operations tpk_port_ops = { |
161 | .shutdown = tpk_port_shutdown, | |
162 | }; | |
24b4b67d SP |
163 | |
164 | static struct tty_driver *ttyprintk_driver; | |
165 | ||
7ea4aa70 VW |
166 | static struct tty_driver *ttyprintk_console_device(struct console *c, |
167 | int *index) | |
168 | { | |
169 | *index = 0; | |
170 | return ttyprintk_driver; | |
171 | } | |
172 | ||
173 | static struct console ttyprintk_console = { | |
174 | .name = "ttyprintk", | |
175 | .device = ttyprintk_console_device, | |
176 | }; | |
177 | ||
24b4b67d SP |
178 | static int __init ttyprintk_init(void) |
179 | { | |
87758935 | 180 | int ret; |
24b4b67d | 181 | |
9a655c77 | 182 | spin_lock_init(&tpk_port.spinlock); |
536a3440 | 183 | |
0019b408 JS |
184 | ttyprintk_driver = tty_alloc_driver(1, |
185 | TTY_DRIVER_RESET_TERMIOS | | |
186 | TTY_DRIVER_REAL_RAW | | |
187 | TTY_DRIVER_UNNUMBERED_NODE); | |
c3a6344a DC |
188 | if (IS_ERR(ttyprintk_driver)) |
189 | return PTR_ERR(ttyprintk_driver); | |
24b4b67d | 190 | |
191c5f10 | 191 | tty_port_init(&tpk_port.port); |
bf3d6ab9 | 192 | tpk_port.port.ops = &tpk_port_ops; |
191c5f10 | 193 | |
24b4b67d SP |
194 | ttyprintk_driver->driver_name = "ttyprintk"; |
195 | ttyprintk_driver->name = "ttyprintk"; | |
196 | ttyprintk_driver->major = TTYAUX_MAJOR; | |
197 | ttyprintk_driver->minor_start = 3; | |
24b4b67d SP |
198 | ttyprintk_driver->type = TTY_DRIVER_TYPE_CONSOLE; |
199 | ttyprintk_driver->init_termios = tty_std_termios; | |
200 | ttyprintk_driver->init_termios.c_oflag = OPOST | OCRNL | ONOCR | ONLRET; | |
24b4b67d | 201 | tty_set_operations(ttyprintk_driver, &ttyprintk_ops); |
b19e2ca7 | 202 | tty_port_link_device(&tpk_port.port, ttyprintk_driver, 0); |
24b4b67d SP |
203 | |
204 | ret = tty_register_driver(ttyprintk_driver); | |
205 | if (ret < 0) { | |
206 | printk(KERN_ERR "Couldn't register ttyprintk driver\n"); | |
207 | goto error; | |
208 | } | |
209 | ||
7ea4aa70 VW |
210 | register_console(&ttyprintk_console); |
211 | ||
24b4b67d SP |
212 | return 0; |
213 | ||
214 | error: | |
9f90a4dd | 215 | tty_driver_kref_put(ttyprintk_driver); |
191c5f10 | 216 | tty_port_destroy(&tpk_port.port); |
24b4b67d SP |
217 | return ret; |
218 | } | |
b24313a8 TI |
219 | |
220 | static void __exit ttyprintk_exit(void) | |
221 | { | |
7ea4aa70 | 222 | unregister_console(&ttyprintk_console); |
b24313a8 | 223 | tty_unregister_driver(ttyprintk_driver); |
9f90a4dd | 224 | tty_driver_kref_put(ttyprintk_driver); |
b24313a8 TI |
225 | tty_port_destroy(&tpk_port.port); |
226 | } | |
227 | ||
db50d2f6 | 228 | device_initcall(ttyprintk_init); |
b24313a8 TI |
229 | module_exit(ttyprintk_exit); |
230 | ||
231 | MODULE_LICENSE("GPL"); |