xref: /openbmc/linux/drivers/auxdisplay/charlcd.c (revision 4daa9ff8)
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