[PATCH] devfs: Remove devfs_mk_cdev() function from the kernel tree
[linux-2.6.git] / drivers / char / vc_screen.c
1 /*
2  * linux/drivers/char/vc_screen.c
3  *
4  * Provide access to virtual console memory.
5  * /dev/vcs0: the screen as it is being viewed right now (possibly scrolled)
6  * /dev/vcsN: the screen of /dev/ttyN (1 <= N <= 63)
7  *            [minor: N]
8  *
9  * /dev/vcsaN: idem, but including attributes, and prefixed with
10  *      the 4 bytes lines,columns,x,y (as screendump used to give).
11  *      Attribute/character pair is in native endianity.
12  *            [minor: N+128]
13  *
14  * This replaces screendump and part of selection, so that the system
15  * administrator can control access using file system permissions.
16  *
17  * aeb@cwi.nl - efter Friedas begravelse - 950211
18  *
19  * machek@k332.feld.cvut.cz - modified not to send characters to wrong console
20  *       - fixed some fatal off-by-one bugs (0-- no longer == -1 -> looping and looping and looping...)
21  *       - making it shorter - scr_readw are macros which expand in PRETTY long code
22  */
23
24 #include <linux/config.h>
25 #include <linux/kernel.h>
26 #include <linux/major.h>
27 #include <linux/errno.h>
28 #include <linux/tty.h>
29 #include <linux/devfs_fs_kernel.h>
30 #include <linux/sched.h>
31 #include <linux/interrupt.h>
32 #include <linux/mm.h>
33 #include <linux/init.h>
34 #include <linux/vt_kern.h>
35 #include <linux/selection.h>
36 #include <linux/kbd_kern.h>
37 #include <linux/console.h>
38 #include <linux/smp_lock.h>
39 #include <linux/device.h>
40 #include <asm/uaccess.h>
41 #include <asm/byteorder.h>
42 #include <asm/unaligned.h>
43
44 #undef attr
45 #undef org
46 #undef addr
47 #define HEADER_SIZE     4
48
49 static int
50 vcs_size(struct inode *inode)
51 {
52         int size;
53         int minor = iminor(inode);
54         int currcons = minor & 127;
55         struct vc_data *vc;
56
57         if (currcons == 0)
58                 currcons = fg_console;
59         else
60                 currcons--;
61         if (!vc_cons_allocated(currcons))
62                 return -ENXIO;
63         vc = vc_cons[currcons].d;
64
65         size = vc->vc_rows * vc->vc_cols;
66
67         if (minor & 128)
68                 size = 2*size + HEADER_SIZE;
69         return size;
70 }
71
72 static loff_t vcs_lseek(struct file *file, loff_t offset, int orig)
73 {
74         int size;
75
76         down(&con_buf_sem);
77         size = vcs_size(file->f_dentry->d_inode);
78         switch (orig) {
79                 default:
80                         up(&con_buf_sem);
81                         return -EINVAL;
82                 case 2:
83                         offset += size;
84                         break;
85                 case 1:
86                         offset += file->f_pos;
87                 case 0:
88                         break;
89         }
90         if (offset < 0 || offset > size) {
91                 up(&con_buf_sem);
92                 return -EINVAL;
93         }
94         file->f_pos = offset;
95         up(&con_buf_sem);
96         return file->f_pos;
97 }
98
99
100 static ssize_t
101 vcs_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
102 {
103         struct inode *inode = file->f_dentry->d_inode;
104         unsigned int currcons = iminor(inode);
105         struct vc_data *vc;
106         long pos;
107         long viewed, attr, read;
108         int col, maxcol;
109         unsigned short *org = NULL;
110         ssize_t ret;
111
112         down(&con_buf_sem);
113
114         pos = *ppos;
115
116         /* Select the proper current console and verify
117          * sanity of the situation under the console lock.
118          */
119         acquire_console_sem();
120
121         attr = (currcons & 128);
122         currcons = (currcons & 127);
123         if (currcons == 0) {
124                 currcons = fg_console;
125                 viewed = 1;
126         } else {
127                 currcons--;
128                 viewed = 0;
129         }
130         ret = -ENXIO;
131         if (!vc_cons_allocated(currcons))
132                 goto unlock_out;
133         vc = vc_cons[currcons].d;
134
135         ret = -EINVAL;
136         if (pos < 0)
137                 goto unlock_out;
138         read = 0;
139         ret = 0;
140         while (count) {
141                 char *con_buf0, *con_buf_start;
142                 long this_round, size;
143                 ssize_t orig_count;
144                 long p = pos;
145
146                 /* Check whether we are above size each round,
147                  * as copy_to_user at the end of this loop
148                  * could sleep.
149                  */
150                 size = vcs_size(inode);
151                 if (pos >= size)
152                         break;
153                 if (count > size - pos)
154                         count = size - pos;
155
156                 this_round = count;
157                 if (this_round > CON_BUF_SIZE)
158                         this_round = CON_BUF_SIZE;
159
160                 /* Perform the whole read into the local con_buf.
161                  * Then we can drop the console spinlock and safely
162                  * attempt to move it to userspace.
163                  */
164
165                 con_buf_start = con_buf0 = con_buf;
166                 orig_count = this_round;
167                 maxcol = vc->vc_cols;
168                 if (!attr) {
169                         org = screen_pos(vc, p, viewed);
170                         col = p % maxcol;
171                         p += maxcol - col;
172                         while (this_round-- > 0) {
173                                 *con_buf0++ = (vcs_scr_readw(vc, org++) & 0xff);
174                                 if (++col == maxcol) {
175                                         org = screen_pos(vc, p, viewed);
176                                         col = 0;
177                                         p += maxcol;
178                                 }
179                         }
180                 } else {
181                         if (p < HEADER_SIZE) {
182                                 size_t tmp_count;
183
184                                 con_buf0[0] = (char)vc->vc_rows;
185                                 con_buf0[1] = (char)vc->vc_cols;
186                                 getconsxy(vc, con_buf0 + 2);
187
188                                 con_buf_start += p;
189                                 this_round += p;
190                                 if (this_round > CON_BUF_SIZE) {
191                                         this_round = CON_BUF_SIZE;
192                                         orig_count = this_round - p;
193                                 }
194
195                                 tmp_count = HEADER_SIZE;
196                                 if (tmp_count > this_round)
197                                         tmp_count = this_round;
198
199                                 /* Advance state pointers and move on. */
200                                 this_round -= tmp_count;
201                                 p = HEADER_SIZE;
202                                 con_buf0 = con_buf + HEADER_SIZE;
203                                 /* If this_round >= 0, then p is even... */
204                         } else if (p & 1) {
205                                 /* Skip first byte for output if start address is odd
206                                  * Update region sizes up/down depending on free
207                                  * space in buffer.
208                                  */
209                                 con_buf_start++;
210                                 if (this_round < CON_BUF_SIZE)
211                                         this_round++;
212                                 else
213                                         orig_count--;
214                         }
215                         if (this_round > 0) {
216                                 unsigned short *tmp_buf = (unsigned short *)con_buf0;
217
218                                 p -= HEADER_SIZE;
219                                 p /= 2;
220                                 col = p % maxcol;
221
222                                 org = screen_pos(vc, p, viewed);
223                                 p += maxcol - col;
224
225                                 /* Buffer has even length, so we can always copy
226                                  * character + attribute. We do not copy last byte
227                                  * to userspace if this_round is odd.
228                                  */
229                                 this_round = (this_round + 1) >> 1;
230
231                                 while (this_round) {
232                                         *tmp_buf++ = vcs_scr_readw(vc, org++);
233                                         this_round --;
234                                         if (++col == maxcol) {
235                                                 org = screen_pos(vc, p, viewed);
236                                                 col = 0;
237                                                 p += maxcol;
238                                         }
239                                 }
240                         }
241                 }
242
243                 /* Finally, release the console semaphore while we push
244                  * all the data to userspace from our temporary buffer.
245                  *
246                  * AKPM: Even though it's a semaphore, we should drop it because
247                  * the pagefault handling code may want to call printk().
248                  */
249
250                 release_console_sem();
251                 ret = copy_to_user(buf, con_buf_start, orig_count);
252                 acquire_console_sem();
253
254                 if (ret) {
255                         read += (orig_count - ret);
256                         ret = -EFAULT;
257                         break;
258                 }
259                 buf += orig_count;
260                 pos += orig_count;
261                 read += orig_count;
262                 count -= orig_count;
263         }
264         *ppos += read;
265         if (read)
266                 ret = read;
267 unlock_out:
268         release_console_sem();
269         up(&con_buf_sem);
270         return ret;
271 }
272
273 static ssize_t
274 vcs_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
275 {
276         struct inode *inode = file->f_dentry->d_inode;
277         unsigned int currcons = iminor(inode);
278         struct vc_data *vc;
279         long pos;
280         long viewed, attr, size, written;
281         char *con_buf0;
282         int col, maxcol;
283         u16 *org0 = NULL, *org = NULL;
284         size_t ret;
285
286         down(&con_buf_sem);
287
288         pos = *ppos;
289
290         /* Select the proper current console and verify
291          * sanity of the situation under the console lock.
292          */
293         acquire_console_sem();
294
295         attr = (currcons & 128);
296         currcons = (currcons & 127);
297
298         if (currcons == 0) {
299                 currcons = fg_console;
300                 viewed = 1;
301         } else {
302                 currcons--;
303                 viewed = 0;
304         }
305         ret = -ENXIO;
306         if (!vc_cons_allocated(currcons))
307                 goto unlock_out;
308         vc = vc_cons[currcons].d;
309
310         size = vcs_size(inode);
311         ret = -EINVAL;
312         if (pos < 0 || pos > size)
313                 goto unlock_out;
314         if (count > size - pos)
315                 count = size - pos;
316         written = 0;
317         while (count) {
318                 long this_round = count;
319                 size_t orig_count;
320                 long p;
321
322                 if (this_round > CON_BUF_SIZE)
323                         this_round = CON_BUF_SIZE;
324
325                 /* Temporarily drop the console lock so that we can read
326                  * in the write data from userspace safely.
327                  */
328                 release_console_sem();
329                 ret = copy_from_user(con_buf, buf, this_round);
330                 acquire_console_sem();
331
332                 if (ret) {
333                         this_round -= ret;
334                         if (!this_round) {
335                                 /* Abort loop if no data were copied. Otherwise
336                                  * fail with -EFAULT.
337                                  */
338                                 if (written)
339                                         break;
340                                 ret = -EFAULT;
341                                 goto unlock_out;
342                         }
343                 }
344
345                 /* The vcs_size might have changed while we slept to grab
346                  * the user buffer, so recheck.
347                  * Return data written up to now on failure.
348                  */
349                 size = vcs_size(inode);
350                 if (pos >= size)
351                         break;
352                 if (this_round > size - pos)
353                         this_round = size - pos;
354
355                 /* OK, now actually push the write to the console
356                  * under the lock using the local kernel buffer.
357                  */
358
359                 con_buf0 = con_buf;
360                 orig_count = this_round;
361                 maxcol = vc->vc_cols;
362                 p = pos;
363                 if (!attr) {
364                         org0 = org = screen_pos(vc, p, viewed);
365                         col = p % maxcol;
366                         p += maxcol - col;
367
368                         while (this_round > 0) {
369                                 unsigned char c = *con_buf0++;
370
371                                 this_round--;
372                                 vcs_scr_writew(vc,
373                                                (vcs_scr_readw(vc, org) & 0xff00) | c, org);
374                                 org++;
375                                 if (++col == maxcol) {
376                                         org = screen_pos(vc, p, viewed);
377                                         col = 0;
378                                         p += maxcol;
379                                 }
380                         }
381                 } else {
382                         if (p < HEADER_SIZE) {
383                                 char header[HEADER_SIZE];
384
385                                 getconsxy(vc, header + 2);
386                                 while (p < HEADER_SIZE && this_round > 0) {
387                                         this_round--;
388                                         header[p++] = *con_buf0++;
389                                 }
390                                 if (!viewed)
391                                         putconsxy(vc, header + 2);
392                         }
393                         p -= HEADER_SIZE;
394                         col = (p/2) % maxcol;
395                         if (this_round > 0) {
396                                 org0 = org = screen_pos(vc, p/2, viewed);
397                                 if ((p & 1) && this_round > 0) {
398                                         char c;
399
400                                         this_round--;
401                                         c = *con_buf0++;
402 #ifdef __BIG_ENDIAN
403                                         vcs_scr_writew(vc, c |
404                                              (vcs_scr_readw(vc, org) & 0xff00), org);
405 #else
406                                         vcs_scr_writew(vc, (c << 8) |
407                                              (vcs_scr_readw(vc, org) & 0xff), org);
408 #endif
409                                         org++;
410                                         p++;
411                                         if (++col == maxcol) {
412                                                 org = screen_pos(vc, p/2, viewed);
413                                                 col = 0;
414                                         }
415                                 }
416                                 p /= 2;
417                                 p += maxcol - col;
418                         }
419                         while (this_round > 1) {
420                                 unsigned short w;
421
422                                 w = get_unaligned(((unsigned short *)con_buf0));
423                                 vcs_scr_writew(vc, w, org++);
424                                 con_buf0 += 2;
425                                 this_round -= 2;
426                                 if (++col == maxcol) {
427                                         org = screen_pos(vc, p, viewed);
428                                         col = 0;
429                                         p += maxcol;
430                                 }
431                         }
432                         if (this_round > 0) {
433                                 unsigned char c;
434
435                                 c = *con_buf0++;
436 #ifdef __BIG_ENDIAN
437                                 vcs_scr_writew(vc, (vcs_scr_readw(vc, org) & 0xff) | (c << 8), org);
438 #else
439                                 vcs_scr_writew(vc, (vcs_scr_readw(vc, org) & 0xff00) | c, org);
440 #endif
441                         }
442                 }
443                 count -= orig_count;
444                 written += orig_count;
445                 buf += orig_count;
446                 pos += orig_count;
447                 if (org0)
448                         update_region(vc, (unsigned long)(org0), org - org0);
449         }
450         *ppos += written;
451         ret = written;
452
453 unlock_out:
454         release_console_sem();
455
456         up(&con_buf_sem);
457
458         return ret;
459 }
460
461 static int
462 vcs_open(struct inode *inode, struct file *filp)
463 {
464         unsigned int currcons = iminor(inode) & 127;
465         if(currcons && !vc_cons_allocated(currcons-1))
466                 return -ENXIO;
467         return 0;
468 }
469
470 static struct file_operations vcs_fops = {
471         .llseek         = vcs_lseek,
472         .read           = vcs_read,
473         .write          = vcs_write,
474         .open           = vcs_open,
475 };
476
477 static struct class *vc_class;
478
479 void vcs_make_devfs(struct tty_struct *tty)
480 {
481         class_device_create(vc_class, NULL, MKDEV(VCS_MAJOR, tty->index + 1),
482                         NULL, "vcs%u", tty->index + 1);
483         class_device_create(vc_class, NULL, MKDEV(VCS_MAJOR, tty->index + 129),
484                         NULL, "vcsa%u", tty->index + 1);
485 }
486 void vcs_remove_devfs(struct tty_struct *tty)
487 {
488         devfs_remove("vcc/%u", tty->index + 1);
489         devfs_remove("vcc/a%u", tty->index + 1);
490         class_device_destroy(vc_class, MKDEV(VCS_MAJOR, tty->index + 1));
491         class_device_destroy(vc_class, MKDEV(VCS_MAJOR, tty->index + 129));
492 }
493
494 int __init vcs_init(void)
495 {
496         if (register_chrdev(VCS_MAJOR, "vcs", &vcs_fops))
497                 panic("unable to get major %d for vcs device", VCS_MAJOR);
498         vc_class = class_create(THIS_MODULE, "vc");
499
500         class_device_create(vc_class, NULL, MKDEV(VCS_MAJOR, 0), NULL, "vcs");
501         class_device_create(vc_class, NULL, MKDEV(VCS_MAJOR, 128), NULL, "vcsa");
502         return 0;
503 }