media: tegra: enable a clock for VIP in APB MISC register
[linux-2.6.git] / drivers / char / ttyprintk.c
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>
20
21 struct ttyprintk_port {
22         struct tty_port port;
23         struct mutex port_write_mutex;
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
33  * - too long message is fragmeted, with '\'nl between fragments
34  * - TPK_STR_SIZE isn't really the write_room limiting factor, bcause
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 */
39 static const char *tpk_tag = "[U] "; /* U for User */
40 static int tpk_curr;
41
42 static int tpk_printk(const unsigned char *buf, int count)
43 {
44         static char tmp[TPK_STR_SIZE + 4];
45         int i = tpk_curr;
46
47         if (buf == NULL) {
48                 /* flush tmp[] */
49                 if (tpk_curr > 0) {
50                         /* non nl or cr terminated message - add nl */
51                         tmp[tpk_curr + 0] = '\n';
52                         tmp[tpk_curr + 1] = '\0';
53                         printk(KERN_INFO "%s%s", tpk_tag, tmp);
54                         tpk_curr = 0;
55                 }
56                 return i;
57         }
58
59         for (i = 0; i < count; i++) {
60                 tmp[tpk_curr] = buf[i];
61                 if (tpk_curr < TPK_STR_SIZE) {
62                         switch (buf[i]) {
63                         case '\r':
64                                 /* replace cr with nl */
65                                 tmp[tpk_curr + 0] = '\n';
66                                 tmp[tpk_curr + 1] = '\0';
67                                 printk(KERN_INFO "%s%s", tpk_tag, tmp);
68                                 tpk_curr = 0;
69                                 if (buf[i + 1] == '\n')
70                                         i++;
71                                 break;
72                         case '\n':
73                                 tmp[tpk_curr + 1] = '\0';
74                                 printk(KERN_INFO "%s%s", tpk_tag, tmp);
75                                 tpk_curr = 0;
76                                 break;
77                         default:
78                                 tpk_curr++;
79                         }
80                 } else {
81                         /* end of tmp buffer reached: cut the message in two */
82                         tmp[tpk_curr + 1] = '\\';
83                         tmp[tpk_curr + 2] = '\n';
84                         tmp[tpk_curr + 3] = '\0';
85                         printk(KERN_INFO "%s%s", tpk_tag, tmp);
86                         tpk_curr = 0;
87                 }
88         }
89
90         return count;
91 }
92
93 /*
94  * TTY operations open function.
95  */
96 static int tpk_open(struct tty_struct *tty, struct file *filp)
97 {
98         tty->driver_data = &tpk_port;
99
100         return tty_port_open(&tpk_port.port, tty, filp);
101 }
102
103 /*
104  * TTY operations close function.
105  */
106 static void tpk_close(struct tty_struct *tty, struct file *filp)
107 {
108         struct ttyprintk_port *tpkp = tty->driver_data;
109
110         mutex_lock(&tpkp->port_write_mutex);
111         /* flush tpk_printk buffer */
112         tpk_printk(NULL, 0);
113         mutex_unlock(&tpkp->port_write_mutex);
114
115         tty_port_close(&tpkp->port, tty, filp);
116 }
117
118 /*
119  * TTY operations write function.
120  */
121 static int tpk_write(struct tty_struct *tty,
122                 const unsigned char *buf, int count)
123 {
124         struct ttyprintk_port *tpkp = tty->driver_data;
125         int ret;
126
127
128         /* exclusive use of tpk_printk within this tty */
129         mutex_lock(&tpkp->port_write_mutex);
130         ret = tpk_printk(buf, count);
131         mutex_unlock(&tpkp->port_write_mutex);
132
133         return ret;
134 }
135
136 /*
137  * TTY operations write_room function.
138  */
139 static int tpk_write_room(struct tty_struct *tty)
140 {
141         return TPK_MAX_ROOM;
142 }
143
144 /*
145  * TTY operations ioctl function.
146  */
147 static int tpk_ioctl(struct tty_struct *tty,
148                         unsigned int cmd, unsigned long arg)
149 {
150         struct ttyprintk_port *tpkp = tty->driver_data;
151
152         if (!tpkp)
153                 return -EINVAL;
154
155         switch (cmd) {
156         /* Stop TIOCCONS */
157         case TIOCCONS:
158                 return -EOPNOTSUPP;
159         default:
160                 return -ENOIOCTLCMD;
161         }
162         return 0;
163 }
164
165 static const struct tty_operations ttyprintk_ops = {
166         .open = tpk_open,
167         .close = tpk_close,
168         .write = tpk_write,
169         .write_room = tpk_write_room,
170         .ioctl = tpk_ioctl,
171 };
172
173 struct tty_port_operations null_ops = { };
174
175 static struct tty_driver *ttyprintk_driver;
176
177 static int __init ttyprintk_init(void)
178 {
179         int ret = -ENOMEM;
180         void *rp;
181
182         ttyprintk_driver = alloc_tty_driver(1);
183         if (!ttyprintk_driver)
184                 return ret;
185
186         ttyprintk_driver->owner = THIS_MODULE;
187         ttyprintk_driver->driver_name = "ttyprintk";
188         ttyprintk_driver->name = "ttyprintk";
189         ttyprintk_driver->major = TTYAUX_MAJOR;
190         ttyprintk_driver->minor_start = 3;
191         ttyprintk_driver->num = 1;
192         ttyprintk_driver->type = TTY_DRIVER_TYPE_CONSOLE;
193         ttyprintk_driver->init_termios = tty_std_termios;
194         ttyprintk_driver->init_termios.c_oflag = OPOST | OCRNL | ONOCR | ONLRET;
195         ttyprintk_driver->flags = TTY_DRIVER_RESET_TERMIOS |
196                 TTY_DRIVER_REAL_RAW | TTY_DRIVER_DYNAMIC_DEV;
197         tty_set_operations(ttyprintk_driver, &ttyprintk_ops);
198
199         ret = tty_register_driver(ttyprintk_driver);
200         if (ret < 0) {
201                 printk(KERN_ERR "Couldn't register ttyprintk driver\n");
202                 goto error;
203         }
204
205         /* create our unnumbered device */
206         rp = device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 3), NULL,
207                                 ttyprintk_driver->name);
208         if (IS_ERR(rp)) {
209                 printk(KERN_ERR "Couldn't create ttyprintk device\n");
210                 ret = PTR_ERR(rp);
211                 goto error;
212         }
213
214         tty_port_init(&tpk_port.port);
215         tpk_port.port.ops = &null_ops;
216         mutex_init(&tpk_port.port_write_mutex);
217
218         return 0;
219
220 error:
221         put_tty_driver(ttyprintk_driver);
222         ttyprintk_driver = NULL;
223         return ret;
224 }
225 module_init(ttyprintk_init);