1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3 * Character LCD driver for Linux
4 *
5 * Copyright (C) 2000-2008, Willy Tarreau <w@1wt.eu>
6 * Copyright (C) 2016-2017 Glider bvba
7 */
8
9 #include <linux/atomic.h>
10 #include <linux/ctype.h>
11 #include <linux/fs.h>
12 #include <linux/miscdevice.h>
13 #include <linux/module.h>
14 #include <linux/notifier.h>
15 #include <linux/reboot.h>
16 #include <linux/slab.h>
17 #include <linux/uaccess.h>
18 #include <linux/workqueue.h>
19
20 #include <generated/utsrelease.h>
21
22 #include "charlcd.h"
23
24 /* Keep the backlight on this many seconds for each flash */
25 #define LCD_BL_TEMPO_PERIOD 4
26
27 #define LCD_ESCAPE_LEN 24 /* Max chars for LCD escape command */
28 #define LCD_ESCAPE_CHAR 27 /* Use char 27 for escape command */
29
30 struct charlcd_priv {
31 struct charlcd lcd;
32
33 struct delayed_work bl_work;
34 struct mutex bl_tempo_lock; /* Protects access to bl_tempo */
35 bool bl_tempo;
36
37 bool must_clear;
38
39 /* contains the LCD config state */
40 unsigned long flags;
41
42 /* Current escape sequence and it's length or -1 if outside */
43 struct {
44 char buf[LCD_ESCAPE_LEN + 1];
45 int len;
46 } esc_seq;
47
48 unsigned long long drvdata[];
49 };
50
51 #define charlcd_to_priv(p) container_of(p, struct charlcd_priv, lcd)
52
53 /* Device single-open policy control */
54 static atomic_t charlcd_available = ATOMIC_INIT(1);
55
56 /* turn the backlight on or off */
charlcd_backlight(struct charlcd * lcd,enum charlcd_onoff on)57 void charlcd_backlight(struct charlcd *lcd, enum charlcd_onoff on)
58 {
59 struct charlcd_priv *priv = charlcd_to_priv(lcd);
60
61 if (!lcd->ops->backlight)
62 return;
63
64 mutex_lock(&priv->bl_tempo_lock);
65 if (!priv->bl_tempo)
66 lcd->ops->backlight(lcd, on);
67 mutex_unlock(&priv->bl_tempo_lock);
68 }
69 EXPORT_SYMBOL_GPL(charlcd_backlight);
70
charlcd_bl_off(struct work_struct * work)71 static void charlcd_bl_off(struct work_struct *work)
72 {
73 struct delayed_work *dwork = to_delayed_work(work);
74 struct charlcd_priv *priv =
75 container_of(dwork, struct charlcd_priv, bl_work);
76
77 mutex_lock(&priv->bl_tempo_lock);
78 if (priv->bl_tempo) {
79 priv->bl_tempo = false;
80 if (!(priv->flags & LCD_FLAG_L))
81 priv->lcd.ops->backlight(&priv->lcd, CHARLCD_OFF);
82 }
83 mutex_unlock(&priv->bl_tempo_lock);
84 }
85
86 /* turn the backlight on for a little while */
charlcd_poke(struct charlcd * lcd)87 void charlcd_poke(struct charlcd *lcd)
88 {
89 struct charlcd_priv *priv = charlcd_to_priv(lcd);
90
91 if (!lcd->ops->backlight)
92 return;
93
94 cancel_delayed_work_sync(&priv->bl_work);
95
96 mutex_lock(&priv->bl_tempo_lock);
97 if (!priv->bl_tempo && !(priv->flags & LCD_FLAG_L))
98 lcd->ops->backlight(lcd, CHARLCD_ON);
99 priv->bl_tempo = true;
100 schedule_delayed_work(&priv->bl_work, LCD_BL_TEMPO_PERIOD * HZ);
101 mutex_unlock(&priv->bl_tempo_lock);
102 }
103 EXPORT_SYMBOL_GPL(charlcd_poke);
104
charlcd_home(struct charlcd * lcd)105 static void charlcd_home(struct charlcd *lcd)
106 {
107 lcd->addr.x = 0;
108 lcd->addr.y = 0;
109 lcd->ops->home(lcd);
110 }
111
charlcd_print(struct charlcd * lcd,char c)112 static void charlcd_print(struct charlcd *lcd, char c)
113 {
114 if (lcd->addr.x >= lcd->width)
115 return;
116
117 if (lcd->char_conv)
118 c = lcd->char_conv[(unsigned char)c];
119
120 if (!lcd->ops->print(lcd, c))
121 lcd->addr.x++;
122
123 /* prevents the cursor from wrapping onto the next line */
124 if (lcd->addr.x == lcd->width)
125 lcd->ops->gotoxy(lcd, lcd->addr.x - 1, lcd->addr.y);
126 }
127
charlcd_clear_display(struct charlcd * lcd)128 static void charlcd_clear_display(struct charlcd *lcd)
129 {
130 lcd->ops->clear_display(lcd);
131 lcd->addr.x = 0;
132 lcd->addr.y = 0;
133 }
134
135 /*
136 * Parses a movement command of the form "(.*);", where the group can be
137 * any number of subcommands of the form "(x|y)[0-9]+".
138 *
139 * Returns whether the command is valid. The position arguments are
140 * only written if the parsing was successful.
141 *
142 * For instance:
143 * - ";" returns (<original x>, <original y>).
144 * - "x1;" returns (1, <original y>).
145 * - "y2x1;" returns (1, 2).
146 * - "x12y34x56;" returns (56, 34).
147 * - "" fails.
148 * - "x" fails.
149 * - "x;" fails.
150 * - "x1" fails.
151 * - "xy12;" fails.
152 * - "x12yy12;" fails.
153 * - "xx" fails.
154 */
parse_xy(const char * s,unsigned long * x,unsigned long * y)155 static bool parse_xy(const char *s, unsigned long *x, unsigned long *y)
156 {
157 unsigned long new_x = *x;
158 unsigned long new_y = *y;
159 char *p;
160
161 for (;;) {
162 if (!*s)
163 return false;
164
165 if (*s == ';')
166 break;
167
168 if (*s == 'x') {
169 new_x = simple_strtoul(s + 1, &p, 10);
170 if (p == s + 1)
171 return false;
172 s = p;
173 } else if (*s == 'y') {
174 new_y = simple_strtoul(s + 1, &p, 10);
175 if (p == s + 1)
176 return false;
177 s = p;
178 } else {
179 return false;
180 }
181 }
182
183 *x = new_x;
184 *y = new_y;
185 return true;
186 }
187
188 /*
189 * These are the file operation function for user access to /dev/lcd
190 * This function can also be called from inside the kernel, by
191 * setting file and ppos to NULL.
192 *
193 */
194
handle_lcd_special_code(struct charlcd * lcd)195 static inline int handle_lcd_special_code(struct charlcd *lcd)
196 {
197 struct charlcd_priv *priv = charlcd_to_priv(lcd);
198
199 /* LCD special codes */
200
201 int processed = 0;
202
203 char *esc = priv->esc_seq.buf + 2;
204 int oldflags = priv->flags;
205
206 /* check for display mode flags */
207 switch (*esc) {
208 case 'D': /* Display ON */
209 priv->flags |= LCD_FLAG_D;
210 if (priv->flags != oldflags)
211 lcd->ops->display(lcd, CHARLCD_ON);
212
213 processed = 1;
214 break;
215 case 'd': /* Display OFF */
216 priv->flags &= ~LCD_FLAG_D;
217 if (priv->flags != oldflags)
218 lcd->ops->display(lcd, CHARLCD_OFF);
219
220 processed = 1;
221 break;
222 case 'C': /* Cursor ON */
223 priv->flags |= LCD_FLAG_C;
224 if (priv->flags != oldflags)
225 lcd->ops->cursor(lcd, CHARLCD_ON);
226
227 processed = 1;
228 break;
229 case 'c': /* Cursor OFF */
230 priv->flags &= ~LCD_FLAG_C;
231 if (priv->flags != oldflags)
232 lcd->ops->cursor(lcd, CHARLCD_OFF);
233
234 processed = 1;
235 break;
236 case 'B': /* Blink ON */
237 priv->flags |= LCD_FLAG_B;
238 if (priv->flags != oldflags)
239 lcd->ops->blink(lcd, CHARLCD_ON);
240
241 processed = 1;
242 break;
243 case 'b': /* Blink OFF */
244 priv->flags &= ~LCD_FLAG_B;
245 if (priv->flags != oldflags)
246 lcd->ops->blink(lcd, CHARLCD_OFF);
247
248 processed = 1;
249 break;
250 case '+': /* Back light ON */
251 priv->flags |= LCD_FLAG_L;
252 if (priv->flags != oldflags)
253 charlcd_backlight(lcd, CHARLCD_ON);
254
255 processed = 1;
256 break;
257 case '-': /* Back light OFF */
258 priv->flags &= ~LCD_FLAG_L;
259 if (priv->flags != oldflags)
260 charlcd_backlight(lcd, CHARLCD_OFF);
261
262 processed = 1;
263 break;
264 case '*': /* Flash back light */
265 charlcd_poke(lcd);
266 processed = 1;
267 break;
268 case 'f': /* Small Font */
269 priv->flags &= ~LCD_FLAG_F;
270 if (priv->flags != oldflags)
271 lcd->ops->fontsize(lcd, CHARLCD_FONTSIZE_SMALL);
272
273 processed = 1;
274 break;
275 case 'F': /* Large Font */
276 priv->flags |= LCD_FLAG_F;
277 if (priv->flags != oldflags)
278 lcd->ops->fontsize(lcd, CHARLCD_FONTSIZE_LARGE);
279
280 processed = 1;
281 break;
282 case 'n': /* One Line */
283 priv->flags &= ~LCD_FLAG_N;
284 if (priv->flags != oldflags)
285 lcd->ops->lines(lcd, CHARLCD_LINES_1);
286
287 processed = 1;
288 break;
289 case 'N': /* Two Lines */
290 priv->flags |= LCD_FLAG_N;
291 if (priv->flags != oldflags)
292 lcd->ops->lines(lcd, CHARLCD_LINES_2);
293
294 processed = 1;
295 break;
296 case 'l': /* Shift Cursor Left */
297 if (lcd->addr.x > 0) {
298 if (!lcd->ops->shift_cursor(lcd, CHARLCD_SHIFT_LEFT))
299 lcd->addr.x--;
300 }
301
302 processed = 1;
303 break;
304 case 'r': /* shift cursor right */
305 if (lcd->addr.x < lcd->width) {
306 if (!lcd->ops->shift_cursor(lcd, CHARLCD_SHIFT_RIGHT))
307 lcd->addr.x++;
308 }
309
310 processed = 1;
311 break;
312 case 'L': /* shift display left */
313 lcd->ops->shift_display(lcd, CHARLCD_SHIFT_LEFT);
314 processed = 1;
315 break;
316 case 'R': /* shift display right */
317 lcd->ops->shift_display(lcd, CHARLCD_SHIFT_RIGHT);
318 processed = 1;
319 break;
320 case 'k': { /* kill end of line */
321 int x, xs, ys;
322
323 xs = lcd->addr.x;
324 ys = lcd->addr.y;
325 for (x = lcd->addr.x; x < lcd->width; x++)
326 lcd->ops->print(lcd, ' ');
327
328 /* restore cursor position */
329 lcd->addr.x = xs;
330 lcd->addr.y = ys;
331 lcd->ops->gotoxy(lcd, lcd->addr.x, lcd->addr.y);
332 processed = 1;
333 break;
334 }
335 case 'I': /* reinitialize display */
336 lcd->ops->init_display(lcd);
337 priv->flags = ((lcd->height > 1) ? LCD_FLAG_N : 0) | LCD_FLAG_D |
338 LCD_FLAG_C | LCD_FLAG_B;
339 processed = 1;
340 break;
341 case 'G':
342 if (lcd->ops->redefine_char)
343 processed = lcd->ops->redefine_char(lcd, esc);
344 else
345 processed = 1;
346 break;
347
348 case 'x': /* gotoxy : LxXXX[yYYY]; */
349 case 'y': /* gotoxy : LyYYY[xXXX]; */
350 if (priv->esc_seq.buf[priv->esc_seq.len - 1] != ';')
351 break;
352
353 /* If the command is valid, move to the new address */
354 if (parse_xy(esc, &lcd->addr.x, &lcd->addr.y))
355 lcd->ops->gotoxy(lcd, lcd->addr.x, lcd->addr.y);
356
357 /* Regardless of its validity, mark as processed */
358 processed = 1;
359 break;
360 }
361
362 return processed;
363 }
364
charlcd_write_char(struct charlcd * lcd,char c)365 static void charlcd_write_char(struct charlcd *lcd, char c)
366 {
367 struct charlcd_priv *priv = charlcd_to_priv(lcd);
368
369 /* first, we'll test if we're in escape mode */
370 if ((c != '\n') && priv->esc_seq.len >= 0) {
371 /* yes, let's add this char to the buffer */
372 priv->esc_seq.buf[priv->esc_seq.len++] = c;
373 priv->esc_seq.buf[priv->esc_seq.len] = '\0';
374 } else {
375 /* aborts any previous escape sequence */
376 priv->esc_seq.len = -1;
377
378 switch (c) {
379 case LCD_ESCAPE_CHAR:
380 /* start of an escape sequence */
381 priv->esc_seq.len = 0;
382 priv->esc_seq.buf[priv->esc_seq.len] = '\0';
383 break;
384 case '\b':
385 /* go back one char and clear it */
386 if (lcd->addr.x > 0) {
387 /* back one char */
388 if (!lcd->ops->shift_cursor(lcd,
389 CHARLCD_SHIFT_LEFT))
390 lcd->addr.x--;
391 }
392 /* replace with a space */
393 charlcd_print(lcd, ' ');
394 /* back one char again */
395 if (!lcd->ops->shift_cursor(lcd, CHARLCD_SHIFT_LEFT))
396 lcd->addr.x--;
397
398 break;
399 case '\f':
400 /* quickly clear the display */
401 charlcd_clear_display(lcd);
402 break;
403 case '\n':
404 /*
405 * flush the remainder of the current line and
406 * go to the beginning of the next line
407 */
408 for (; lcd->addr.x < lcd->width; lcd->addr.x++)
409 lcd->ops->print(lcd, ' ');
410
411 lcd->addr.x = 0;
412 lcd->addr.y = (lcd->addr.y + 1) % lcd->height;
413 lcd->ops->gotoxy(lcd, lcd->addr.x, lcd->addr.y);
414 break;
415 case '\r':
416 /* go to the beginning of the same line */
417 lcd->addr.x = 0;
418 lcd->ops->gotoxy(lcd, lcd->addr.x, lcd->addr.y);
419 break;
420 case '\t':
421 /* print a space instead of the tab */
422 charlcd_print(lcd, ' ');
423 break;
424 default:
425 /* simply print this char */
426 charlcd_print(lcd, c);
427 break;
428 }
429 }
430
431 /*
432 * now we'll see if we're in an escape mode and if the current
433 * escape sequence can be understood.
434 */
435 if (priv->esc_seq.len >= 2) {
436 int processed = 0;
437
438 if (!strcmp(priv->esc_seq.buf, "[2J")) {
439 /* clear the display */
440 charlcd_clear_display(lcd);
441 processed = 1;
442 } else if (!strcmp(priv->esc_seq.buf, "[H")) {
443 /* cursor to home */
444 charlcd_home(lcd);
445 processed = 1;
446 }
447 /* codes starting with ^[[L */
448 else if ((priv->esc_seq.len >= 3) &&
449 (priv->esc_seq.buf[0] == '[') &&
450 (priv->esc_seq.buf[1] == 'L')) {
451 processed = handle_lcd_special_code(lcd);
452 }
453
454 /* LCD special escape codes */
455 /*
456 * flush the escape sequence if it's been processed
457 * or if it is getting too long.
458 */
459 if (processed || (priv->esc_seq.len >= LCD_ESCAPE_LEN))
460 priv->esc_seq.len = -1;
461 } /* escape codes */
462 }
463
464 static struct charlcd *the_charlcd;
465
charlcd_write(struct file * file,const char __user * buf,size_t count,loff_t * ppos)466 static ssize_t charlcd_write(struct file *file, const char __user *buf,
467 size_t count, loff_t *ppos)
468 {
469 const char __user *tmp = buf;
470 char c;
471
472 for (; count-- > 0; (*ppos)++, tmp++) {
473 if (((count + 1) & 0x1f) == 0) {
474 /*
475 * charlcd_write() is invoked as a VFS->write() callback
476 * and as such it is always invoked from preemptible
477 * context and may sleep.
478 */
479 cond_resched();
480 }
481
482 if (get_user(c, tmp))
483 return -EFAULT;
484
485 charlcd_write_char(the_charlcd, c);
486 }
487
488 return tmp - buf;
489 }
490
charlcd_open(struct inode * inode,struct file * file)491 static int charlcd_open(struct inode *inode, struct file *file)
492 {
493 struct charlcd_priv *priv = charlcd_to_priv(the_charlcd);
494 int ret;
495
496 ret = -EBUSY;
497 if (!atomic_dec_and_test(&charlcd_available))
498 goto fail; /* open only once at a time */
499
500 ret = -EPERM;
501 if (file->f_mode & FMODE_READ) /* device is write-only */
502 goto fail;
503
504 if (priv->must_clear) {
505 priv->lcd.ops->clear_display(&priv->lcd);
506 priv->must_clear = false;
507 priv->lcd.addr.x = 0;
508 priv->lcd.addr.y = 0;
509 }
510 return nonseekable_open(inode, file);
511
512 fail:
513 atomic_inc(&charlcd_available);
514 return ret;
515 }
516
charlcd_release(struct inode * inode,struct file * file)517 static int charlcd_release(struct inode *inode, struct file *file)
518 {
519 atomic_inc(&charlcd_available);
520 return 0;
521 }
522
523 static const struct file_operations charlcd_fops = {
524 .write = charlcd_write,
525 .open = charlcd_open,
526 .release = charlcd_release,
527 .llseek = no_llseek,
528 };
529
530 static struct miscdevice charlcd_dev = {
531 .minor = LCD_MINOR,
532 .name = "lcd",
533 .fops = &charlcd_fops,
534 };
535
charlcd_puts(struct charlcd * lcd,const char * s)536 static void charlcd_puts(struct charlcd *lcd, const char *s)
537 {
538 const char *tmp = s;
539 int count = strlen(s);
540
541 for (; count-- > 0; tmp++) {
542 if (((count + 1) & 0x1f) == 0)
543 cond_resched();
544
545 charlcd_write_char(lcd, *tmp);
546 }
547 }
548
549 #ifdef CONFIG_PANEL_BOOT_MESSAGE
550 #define LCD_INIT_TEXT CONFIG_PANEL_BOOT_MESSAGE
551 #else
552 #define LCD_INIT_TEXT "Linux-" UTS_RELEASE "\n"
553 #endif
554
555 #ifdef CONFIG_CHARLCD_BL_ON
556 #define LCD_INIT_BL "\x1b[L+"
557 #elif defined(CONFIG_CHARLCD_BL_FLASH)
558 #define LCD_INIT_BL "\x1b[L*"
559 #else
560 #define LCD_INIT_BL "\x1b[L-"
561 #endif
562
563 /* initialize the LCD driver */
charlcd_init(struct charlcd * lcd)564 static int charlcd_init(struct charlcd *lcd)
565 {
566 struct charlcd_priv *priv = charlcd_to_priv(lcd);
567 int ret;
568
569 priv->flags = ((lcd->height > 1) ? LCD_FLAG_N : 0) | LCD_FLAG_D |
570 LCD_FLAG_C | LCD_FLAG_B;
571 if (lcd->ops->backlight) {
572 mutex_init(&priv->bl_tempo_lock);
573 INIT_DELAYED_WORK(&priv->bl_work, charlcd_bl_off);
574 }
575
576 /*
577 * before this line, we must NOT send anything to the display.
578 * Since charlcd_init_display() needs to write data, we have to
579 * enable mark the LCD initialized just before.
580 */
581 if (WARN_ON(!lcd->ops->init_display))
582 return -EINVAL;
583
584 ret = lcd->ops->init_display(lcd);
585 if (ret)
586 return ret;
587
588 /* display a short message */
589 charlcd_puts(lcd, "\x1b[Lc\x1b[Lb" LCD_INIT_BL LCD_INIT_TEXT);
590
591 /* clear the display on the next device opening */
592 priv->must_clear = true;
593 charlcd_home(lcd);
594 return 0;
595 }
596
charlcd_alloc(void)597 struct charlcd *charlcd_alloc(void)
598 {
599 struct charlcd_priv *priv;
600 struct charlcd *lcd;
601
602 priv = kzalloc(sizeof(*priv), GFP_KERNEL);
603 if (!priv)
604 return NULL;
605
606 priv->esc_seq.len = -1;
607
608 lcd = &priv->lcd;
609
610 return lcd;
611 }
612 EXPORT_SYMBOL_GPL(charlcd_alloc);
613
charlcd_free(struct charlcd * lcd)614 void charlcd_free(struct charlcd *lcd)
615 {
616 kfree(charlcd_to_priv(lcd));
617 }
618 EXPORT_SYMBOL_GPL(charlcd_free);
619
panel_notify_sys(struct notifier_block * this,unsigned long code,void * unused)620 static int panel_notify_sys(struct notifier_block *this, unsigned long code,
621 void *unused)
622 {
623 struct charlcd *lcd = the_charlcd;
624
625 switch (code) {
626 case SYS_DOWN:
627 charlcd_puts(lcd,
628 "\x0cReloading\nSystem...\x1b[Lc\x1b[Lb\x1b[L+");
629 break;
630 case SYS_HALT:
631 charlcd_puts(lcd, "\x0cSystem Halted.\x1b[Lc\x1b[Lb\x1b[L+");
632 break;
633 case SYS_POWER_OFF:
634 charlcd_puts(lcd, "\x0cPower off.\x1b[Lc\x1b[Lb\x1b[L+");
635 break;
636 default:
637 break;
638 }
639 return NOTIFY_DONE;
640 }
641
642 static struct notifier_block panel_notifier = {
643 .notifier_call = panel_notify_sys,
644 };
645
charlcd_register(struct charlcd * lcd)646 int charlcd_register(struct charlcd *lcd)
647 {
648 int ret;
649
650 ret = charlcd_init(lcd);
651 if (ret)
652 return ret;
653
654 ret = misc_register(&charlcd_dev);
655 if (ret)
656 return ret;
657
658 the_charlcd = lcd;
659 register_reboot_notifier(&panel_notifier);
660 return 0;
661 }
662 EXPORT_SYMBOL_GPL(charlcd_register);
663
charlcd_unregister(struct charlcd * lcd)664 int charlcd_unregister(struct charlcd *lcd)
665 {
666 struct charlcd_priv *priv = charlcd_to_priv(lcd);
667
668 unregister_reboot_notifier(&panel_notifier);
669 charlcd_puts(lcd, "\x0cLCD driver unloaded.\x1b[Lc\x1b[Lb\x1b[L-");
670 misc_deregister(&charlcd_dev);
671 the_charlcd = NULL;
672 if (lcd->ops->backlight) {
673 cancel_delayed_work_sync(&priv->bl_work);
674 priv->lcd.ops->backlight(&priv->lcd, CHARLCD_OFF);
675 }
676
677 return 0;
678 }
679 EXPORT_SYMBOL_GPL(charlcd_unregister);
680
681 MODULE_LICENSE("GPL");
682