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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/delay.h>
12#include <linux/fs.h>
13#include <linux/miscdevice.h>
14#include <linux/module.h>
15#include <linux/notifier.h>
16#include <linux/reboot.h>
17#include <linux/slab.h>
18#include <linux/uaccess.h>
19#include <linux/workqueue.h>
20
21#include <generated/utsrelease.h>
22
23#include "charlcd.h"
24
25#define DEFAULT_LCD_BWIDTH 40
26#define DEFAULT_LCD_HWIDTH 64
27
28/* Keep the backlight on this many seconds for each flash */
29#define LCD_BL_TEMPO_PERIOD 4
30
31#define LCD_FLAG_B 0x0004 /* Blink on */
32#define LCD_FLAG_C 0x0008 /* Cursor on */
33#define LCD_FLAG_D 0x0010 /* Display on */
34#define LCD_FLAG_F 0x0020 /* Large font mode */
35#define LCD_FLAG_N 0x0040 /* 2-rows mode */
36#define LCD_FLAG_L 0x0080 /* Backlight enabled */
37
38/* LCD commands */
39#define LCD_CMD_DISPLAY_CLEAR 0x01 /* Clear entire display */
40
41#define LCD_CMD_ENTRY_MODE 0x04 /* Set entry mode */
42#define LCD_CMD_CURSOR_INC 0x02 /* Increment cursor */
43
44#define LCD_CMD_DISPLAY_CTRL 0x08 /* Display control */
45#define LCD_CMD_DISPLAY_ON 0x04 /* Set display on */
46#define LCD_CMD_CURSOR_ON 0x02 /* Set cursor on */
47#define LCD_CMD_BLINK_ON 0x01 /* Set blink on */
48
49#define LCD_CMD_SHIFT 0x10 /* Shift cursor/display */
50#define LCD_CMD_DISPLAY_SHIFT 0x08 /* Shift display instead of cursor */
51#define LCD_CMD_SHIFT_RIGHT 0x04 /* Shift display/cursor to the right */
52
53#define LCD_CMD_FUNCTION_SET 0x20 /* Set function */
54#define LCD_CMD_DATA_LEN_8BITS 0x10 /* Set data length to 8 bits */
55#define LCD_CMD_TWO_LINES 0x08 /* Set to two display lines */
56#define LCD_CMD_FONT_5X10_DOTS 0x04 /* Set char font to 5x10 dots */
57
58#define LCD_CMD_SET_CGRAM_ADDR 0x40 /* Set char generator RAM address */
59
60#define LCD_CMD_SET_DDRAM_ADDR 0x80 /* Set display data RAM address */
61
62#define LCD_ESCAPE_LEN 24 /* Max chars for LCD escape command */
63#define LCD_ESCAPE_CHAR 27 /* Use char 27 for escape command */
64
65struct charlcd_priv {
66 struct charlcd lcd;
67
68 struct delayed_work bl_work;
69 struct mutex bl_tempo_lock; /* Protects access to bl_tempo */
70 bool bl_tempo;
71
72 bool must_clear;
73
74 /* contains the LCD config state */
75 unsigned long int flags;
76
77 /* Contains the LCD X and Y offset */
78 struct {
79 unsigned long int x;
80 unsigned long int y;
81 } addr;
82
83 /* Current escape sequence and it's length or -1 if outside */
84 struct {
85 char buf[LCD_ESCAPE_LEN + 1];
86 int len;
87 } esc_seq;
88
89 unsigned long long drvdata[];
90};
91
92#define charlcd_to_priv(p) container_of(p, struct charlcd_priv, lcd)
93
94/* Device single-open policy control */
95static atomic_t charlcd_available = ATOMIC_INIT(1);
96
97/* sleeps that many milliseconds with a reschedule */
98static void long_sleep(int ms)
99{
100 schedule_timeout_interruptible(msecs_to_jiffies(ms));
101}
102
103/* turn the backlight on or off */
104static void charlcd_backlight(struct charlcd *lcd, int on)
105{
106 struct charlcd_priv *priv = charlcd_to_priv(lcd);
107
108 if (!lcd->ops->backlight)
109 return;
110
111 mutex_lock(&priv->bl_tempo_lock);
112 if (!priv->bl_tempo)
113 lcd->ops->backlight(lcd, on);
114 mutex_unlock(&priv->bl_tempo_lock);
115}
116
117static void charlcd_bl_off(struct work_struct *work)
118{
119 struct delayed_work *dwork = to_delayed_work(work);
120 struct charlcd_priv *priv =
121 container_of(dwork, struct charlcd_priv, bl_work);
122
123 mutex_lock(&priv->bl_tempo_lock);
124 if (priv->bl_tempo) {
125 priv->bl_tempo = false;
126 if (!(priv->flags & LCD_FLAG_L))
127 priv->lcd.ops->backlight(&priv->lcd, 0);
128 }
129 mutex_unlock(&priv->bl_tempo_lock);
130}
131
132/* turn the backlight on for a little while */
133void charlcd_poke(struct charlcd *lcd)
134{
135 struct charlcd_priv *priv = charlcd_to_priv(lcd);
136
137 if (!lcd->ops->backlight)
138 return;
139
140 cancel_delayed_work_sync(&priv->bl_work);
141
142 mutex_lock(&priv->bl_tempo_lock);
143 if (!priv->bl_tempo && !(priv->flags & LCD_FLAG_L))
144 lcd->ops->backlight(lcd, 1);
145 priv->bl_tempo = true;
146 schedule_delayed_work(&priv->bl_work, LCD_BL_TEMPO_PERIOD * HZ);
147 mutex_unlock(&priv->bl_tempo_lock);
148}
149EXPORT_SYMBOL_GPL(charlcd_poke);
150
151static void charlcd_gotoxy(struct charlcd *lcd)
152{
153 struct charlcd_priv *priv = charlcd_to_priv(lcd);
154 unsigned int addr;
155
156 /*
157 * we force the cursor to stay at the end of the
158 * line if it wants to go farther
159 */
160 addr = priv->addr.x < lcd->bwidth ? priv->addr.x & (lcd->hwidth - 1)
161 : lcd->bwidth - 1;
162 if (priv->addr.y & 1)
163 addr += lcd->hwidth;
164 if (priv->addr.y & 2)
165 addr += lcd->bwidth;
166 lcd->ops->write_cmd(lcd, LCD_CMD_SET_DDRAM_ADDR | addr);
167}
168
169static void charlcd_home(struct charlcd *lcd)
170{
171 struct charlcd_priv *priv = charlcd_to_priv(lcd);
172
173 priv->addr.x = 0;
174 priv->addr.y = 0;
175 charlcd_gotoxy(lcd);
176}
177
178static void charlcd_print(struct charlcd *lcd, char c)
179{
180 struct charlcd_priv *priv = charlcd_to_priv(lcd);
181
182 if (priv->addr.x < lcd->bwidth) {
183 if (lcd->char_conv)
184 c = lcd->char_conv[(unsigned char)c];
185 lcd->ops->write_data(lcd, c);
186 priv->addr.x++;
187
188 /* prevents the cursor from wrapping onto the next line */
189 if (priv->addr.x == lcd->bwidth)
190 charlcd_gotoxy(lcd);
191 }
192}
193
194static void charlcd_clear_fast(struct charlcd *lcd)
195{
196 int pos;
197
198 charlcd_home(lcd);
199
200 if (lcd->ops->clear_fast)
201 lcd->ops->clear_fast(lcd);
202 else
203 for (pos = 0; pos < min(2, lcd->height) * lcd->hwidth; pos++)
204 lcd->ops->write_data(lcd, ' ');
205
206 charlcd_home(lcd);
207}
208
209/* clears the display and resets X/Y */
210static void charlcd_clear_display(struct charlcd *lcd)
211{
212 struct charlcd_priv *priv = charlcd_to_priv(lcd);
213
214 lcd->ops->write_cmd(lcd, LCD_CMD_DISPLAY_CLEAR);
215 priv->addr.x = 0;
216 priv->addr.y = 0;
217 /* we must wait a few milliseconds (15) */
218 long_sleep(15);
219}
220
221static int charlcd_init_display(struct charlcd *lcd)
222{
223 void (*write_cmd_raw)(struct charlcd *lcd, int cmd);
224 struct charlcd_priv *priv = charlcd_to_priv(lcd);
225 u8 init;
226
227 if (lcd->ifwidth != 4 && lcd->ifwidth != 8)
228 return -EINVAL;
229
230 priv->flags = ((lcd->height > 1) ? LCD_FLAG_N : 0) | LCD_FLAG_D |
231 LCD_FLAG_C | LCD_FLAG_B;
232
233 long_sleep(20); /* wait 20 ms after power-up for the paranoid */
234
235 /*
236 * 8-bit mode, 1 line, small fonts; let's do it 3 times, to make sure
237 * the LCD is in 8-bit mode afterwards
238 */
239 init = LCD_CMD_FUNCTION_SET | LCD_CMD_DATA_LEN_8BITS;
240 if (lcd->ifwidth == 4) {
241 init >>= 4;
242 write_cmd_raw = lcd->ops->write_cmd_raw4;
243 } else {
244 write_cmd_raw = lcd->ops->write_cmd;
245 }
246 write_cmd_raw(lcd, init);
247 long_sleep(10);
248 write_cmd_raw(lcd, init);
249 long_sleep(10);
250 write_cmd_raw(lcd, init);
251 long_sleep(10);
252
253 if (lcd->ifwidth == 4) {
254 /* Switch to 4-bit mode, 1 line, small fonts */
255 lcd->ops->write_cmd_raw4(lcd, LCD_CMD_FUNCTION_SET >> 4);
256 long_sleep(10);
257 }
258
259 /* set font height and lines number */
260 lcd->ops->write_cmd(lcd,
261 LCD_CMD_FUNCTION_SET |
262 ((lcd->ifwidth == 8) ? LCD_CMD_DATA_LEN_8BITS : 0) |
263 ((priv->flags & LCD_FLAG_F) ? LCD_CMD_FONT_5X10_DOTS : 0) |
264 ((priv->flags & LCD_FLAG_N) ? LCD_CMD_TWO_LINES : 0));
265 long_sleep(10);
266
267 /* display off, cursor off, blink off */
268 lcd->ops->write_cmd(lcd, LCD_CMD_DISPLAY_CTRL);
269 long_sleep(10);
270
271 lcd->ops->write_cmd(lcd,
272 LCD_CMD_DISPLAY_CTRL | /* set display mode */
273 ((priv->flags & LCD_FLAG_D) ? LCD_CMD_DISPLAY_ON : 0) |
274 ((priv->flags & LCD_FLAG_C) ? LCD_CMD_CURSOR_ON : 0) |
275 ((priv->flags & LCD_FLAG_B) ? LCD_CMD_BLINK_ON : 0));
276
277 charlcd_backlight(lcd, (priv->flags & LCD_FLAG_L) ? 1 : 0);
278
279 long_sleep(10);
280
281 /* entry mode set : increment, cursor shifting */
282 lcd->ops->write_cmd(lcd, LCD_CMD_ENTRY_MODE | LCD_CMD_CURSOR_INC);
283
284 charlcd_clear_display(lcd);
285 return 0;
286}
287
288/*
289 * Parses a movement command of the form "(.*);", where the group can be
290 * any number of subcommands of the form "(x|y)[0-9]+".
291 *
292 * Returns whether the command is valid. The position arguments are
293 * only written if the parsing was successful.
294 *
295 * For instance:
296 * - ";" returns (<original x>, <original y>).
297 * - "x1;" returns (1, <original y>).
298 * - "y2x1;" returns (1, 2).
299 * - "x12y34x56;" returns (56, 34).
300 * - "" fails.
301 * - "x" fails.
302 * - "x;" fails.
303 * - "x1" fails.
304 * - "xy12;" fails.
305 * - "x12yy12;" fails.
306 * - "xx" fails.
307 */
308static bool parse_xy(const char *s, unsigned long *x, unsigned long *y)
309{
310 unsigned long new_x = *x;
311 unsigned long new_y = *y;
312 char *p;
313
314 for (;;) {
315 if (!*s)
316 return false;
317
318 if (*s == ';')
319 break;
320
321 if (*s == 'x') {
322 new_x = simple_strtoul(s + 1, &p, 10);
323 if (p == s + 1)
324 return false;
325 s = p;
326 } else if (*s == 'y') {
327 new_y = simple_strtoul(s + 1, &p, 10);
328 if (p == s + 1)
329 return false;
330 s = p;
331 } else {
332 return false;
333 }
334 }
335
336 *x = new_x;
337 *y = new_y;
338 return true;
339}
340
341/*
342 * These are the file operation function for user access to /dev/lcd
343 * This function can also be called from inside the kernel, by
344 * setting file and ppos to NULL.
345 *
346 */
347
348static inline int handle_lcd_special_code(struct charlcd *lcd)
349{
350 struct charlcd_priv *priv = charlcd_to_priv(lcd);
351
352 /* LCD special codes */
353
354 int processed = 0;
355
356 char *esc = priv->esc_seq.buf + 2;
357 int oldflags = priv->flags;
358
359 /* check for display mode flags */
360 switch (*esc) {
361 case 'D': /* Display ON */
362 priv->flags |= LCD_FLAG_D;
363 processed = 1;
364 break;
365 case 'd': /* Display OFF */
366 priv->flags &= ~LCD_FLAG_D;
367 processed = 1;
368 break;
369 case 'C': /* Cursor ON */
370 priv->flags |= LCD_FLAG_C;
371 processed = 1;
372 break;
373 case 'c': /* Cursor OFF */
374 priv->flags &= ~LCD_FLAG_C;
375 processed = 1;
376 break;
377 case 'B': /* Blink ON */
378 priv->flags |= LCD_FLAG_B;
379 processed = 1;
380 break;
381 case 'b': /* Blink OFF */
382 priv->flags &= ~LCD_FLAG_B;
383 processed = 1;
384 break;
385 case '+': /* Back light ON */
386 priv->flags |= LCD_FLAG_L;
387 processed = 1;
388 break;
389 case '-': /* Back light OFF */
390 priv->flags &= ~LCD_FLAG_L;
391 processed = 1;
392 break;
393 case '*': /* Flash back light */
394 charlcd_poke(lcd);
395 processed = 1;
396 break;
397 case 'f': /* Small Font */
398 priv->flags &= ~LCD_FLAG_F;
399 processed = 1;
400 break;
401 case 'F': /* Large Font */
402 priv->flags |= LCD_FLAG_F;
403 processed = 1;
404 break;
405 case 'n': /* One Line */
406 priv->flags &= ~LCD_FLAG_N;
407 processed = 1;
408 break;
409 case 'N': /* Two Lines */
410 priv->flags |= LCD_FLAG_N;
411 processed = 1;
412 break;
413 case 'l': /* Shift Cursor Left */
414 if (priv->addr.x > 0) {
415 /* back one char if not at end of line */
416 if (priv->addr.x < lcd->bwidth)
417 lcd->ops->write_cmd(lcd, LCD_CMD_SHIFT);
418 priv->addr.x--;
419 }
420 processed = 1;
421 break;
422 case 'r': /* shift cursor right */
423 if (priv->addr.x < lcd->width) {
424 /* allow the cursor to pass the end of the line */
425 if (priv->addr.x < (lcd->bwidth - 1))
426 lcd->ops->write_cmd(lcd,
427 LCD_CMD_SHIFT | LCD_CMD_SHIFT_RIGHT);
428 priv->addr.x++;
429 }
430 processed = 1;
431 break;
432 case 'L': /* shift display left */
433 lcd->ops->write_cmd(lcd, LCD_CMD_SHIFT | LCD_CMD_DISPLAY_SHIFT);
434 processed = 1;
435 break;
436 case 'R': /* shift display right */
437 lcd->ops->write_cmd(lcd,
438 LCD_CMD_SHIFT | LCD_CMD_DISPLAY_SHIFT |
439 LCD_CMD_SHIFT_RIGHT);
440 processed = 1;
441 break;
442 case 'k': { /* kill end of line */
443 int x;
444
445 for (x = priv->addr.x; x < lcd->bwidth; x++)
446 lcd->ops->write_data(lcd, ' ');
447
448 /* restore cursor position */
449 charlcd_gotoxy(lcd);
450 processed = 1;
451 break;
452 }
453 case 'I': /* reinitialize display */
454 charlcd_init_display(lcd);
455 processed = 1;
456 break;
457 case 'G': {
458 /* Generator : LGcxxxxx...xx; must have <c> between '0'
459 * and '7', representing the numerical ASCII code of the
460 * redefined character, and <xx...xx> a sequence of 16
461 * hex digits representing 8 bytes for each character.
462 * Most LCDs will only use 5 lower bits of the 7 first
463 * bytes.
464 */
465
466 unsigned char cgbytes[8];
467 unsigned char cgaddr;
468 int cgoffset;
469 int shift;
470 char value;
471 int addr;
472
473 if (!strchr(esc, ';'))
474 break;
475
476 esc++;
477
478 cgaddr = *(esc++) - '0';
479 if (cgaddr > 7) {
480 processed = 1;
481 break;
482 }
483
484 cgoffset = 0;
485 shift = 0;
486 value = 0;
487 while (*esc && cgoffset < 8) {
488 int half;
489
490 shift ^= 4;
491
492 half = hex_to_bin(*esc++);
493 if (half < 0)
494 continue;
495
496 value |= half << shift;
497 if (shift == 0) {
498 cgbytes[cgoffset++] = value;
499 value = 0;
500 }
501 }
502
503 lcd->ops->write_cmd(lcd, LCD_CMD_SET_CGRAM_ADDR | (cgaddr * 8));
504 for (addr = 0; addr < cgoffset; addr++)
505 lcd->ops->write_data(lcd, cgbytes[addr]);
506
507 /* ensures that we stop writing to CGRAM */
508 charlcd_gotoxy(lcd);
509 processed = 1;
510 break;
511 }
512 case 'x': /* gotoxy : LxXXX[yYYY]; */
513 case 'y': /* gotoxy : LyYYY[xXXX]; */
514 if (priv->esc_seq.buf[priv->esc_seq.len - 1] != ';')
515 break;
516
517 /* If the command is valid, move to the new address */
518 if (parse_xy(esc, &priv->addr.x, &priv->addr.y))
519 charlcd_gotoxy(lcd);
520
521 /* Regardless of its validity, mark as processed */
522 processed = 1;
523 break;
524 }
525
526 /* TODO: This indent party here got ugly, clean it! */
527 /* Check whether one flag was changed */
528 if (oldflags == priv->flags)
529 return processed;
530
531 /* check whether one of B,C,D flags were changed */
532 if ((oldflags ^ priv->flags) &
533 (LCD_FLAG_B | LCD_FLAG_C | LCD_FLAG_D))
534 /* set display mode */
535 lcd->ops->write_cmd(lcd,
536 LCD_CMD_DISPLAY_CTRL |
537 ((priv->flags & LCD_FLAG_D) ? LCD_CMD_DISPLAY_ON : 0) |
538 ((priv->flags & LCD_FLAG_C) ? LCD_CMD_CURSOR_ON : 0) |
539 ((priv->flags & LCD_FLAG_B) ? LCD_CMD_BLINK_ON : 0));
540 /* check whether one of F,N flags was changed */
541 else if ((oldflags ^ priv->flags) & (LCD_FLAG_F | LCD_FLAG_N))
542 lcd->ops->write_cmd(lcd,
543 LCD_CMD_FUNCTION_SET |
544 ((lcd->ifwidth == 8) ? LCD_CMD_DATA_LEN_8BITS : 0) |
545 ((priv->flags & LCD_FLAG_F) ? LCD_CMD_FONT_5X10_DOTS : 0) |
546 ((priv->flags & LCD_FLAG_N) ? LCD_CMD_TWO_LINES : 0));
547 /* check whether L flag was changed */
548 else if ((oldflags ^ priv->flags) & LCD_FLAG_L)
549 charlcd_backlight(lcd, !!(priv->flags & LCD_FLAG_L));
550
551 return processed;
552}
553
554static void charlcd_write_char(struct charlcd *lcd, char c)
555{
556 struct charlcd_priv *priv = charlcd_to_priv(lcd);
557
558 /* first, we'll test if we're in escape mode */
559 if ((c != '\n') && priv->esc_seq.len >= 0) {
560 /* yes, let's add this char to the buffer */
561 priv->esc_seq.buf[priv->esc_seq.len++] = c;
562 priv->esc_seq.buf[priv->esc_seq.len] = '\0';
563 } else {
564 /* aborts any previous escape sequence */
565 priv->esc_seq.len = -1;
566
567 switch (c) {
568 case LCD_ESCAPE_CHAR:
569 /* start of an escape sequence */
570 priv->esc_seq.len = 0;
571 priv->esc_seq.buf[priv->esc_seq.len] = '\0';
572 break;
573 case '\b':
574 /* go back one char and clear it */
575 if (priv->addr.x > 0) {
576 /*
577 * check if we're not at the
578 * end of the line
579 */
580 if (priv->addr.x < lcd->bwidth)
581 /* back one char */
582 lcd->ops->write_cmd(lcd, LCD_CMD_SHIFT);
583 priv->addr.x--;
584 }
585 /* replace with a space */
586 lcd->ops->write_data(lcd, ' ');
587 /* back one char again */
588 lcd->ops->write_cmd(lcd, LCD_CMD_SHIFT);
589 break;
590 case '\f':
591 /* quickly clear the display */
592 charlcd_clear_fast(lcd);
593 break;
594 case '\n':
595 /*
596 * flush the remainder of the current line and
597 * go to the beginning of the next line
598 */
599 for (; priv->addr.x < lcd->bwidth; priv->addr.x++)
600 lcd->ops->write_data(lcd, ' ');
601 priv->addr.x = 0;
602 priv->addr.y = (priv->addr.y + 1) % lcd->height;
603 charlcd_gotoxy(lcd);
604 break;
605 case '\r':
606 /* go to the beginning of the same line */
607 priv->addr.x = 0;
608 charlcd_gotoxy(lcd);
609 break;
610 case '\t':
611 /* print a space instead of the tab */
612 charlcd_print(lcd, ' ');
613 break;
614 default:
615 /* simply print this char */
616 charlcd_print(lcd, c);
617 break;
618 }
619 }
620
621 /*
622 * now we'll see if we're in an escape mode and if the current
623 * escape sequence can be understood.
624 */
625 if (priv->esc_seq.len >= 2) {
626 int processed = 0;
627
628 if (!strcmp(priv->esc_seq.buf, "[2J")) {
629 /* clear the display */
630 charlcd_clear_fast(lcd);
631 processed = 1;
632 } else if (!strcmp(priv->esc_seq.buf, "[H")) {
633 /* cursor to home */
634 charlcd_home(lcd);
635 processed = 1;
636 }
637 /* codes starting with ^[[L */
638 else if ((priv->esc_seq.len >= 3) &&
639 (priv->esc_seq.buf[0] == '[') &&
640 (priv->esc_seq.buf[1] == 'L')) {
641 processed = handle_lcd_special_code(lcd);
642 }
643
644 /* LCD special escape codes */
645 /*
646 * flush the escape sequence if it's been processed
647 * or if it is getting too long.
648 */
649 if (processed || (priv->esc_seq.len >= LCD_ESCAPE_LEN))
650 priv->esc_seq.len = -1;
651 } /* escape codes */
652}
653
654static struct charlcd *the_charlcd;
655
656static ssize_t charlcd_write(struct file *file, const char __user *buf,
657 size_t count, loff_t *ppos)
658{
659 const char __user *tmp = buf;
660 char c;
661
662 for (; count-- > 0; (*ppos)++, tmp++) {
663 if (!in_interrupt() && (((count + 1) & 0x1f) == 0))
664 /*
665 * let's be a little nice with other processes
666 * that need some CPU
667 */
668 schedule();
669
670 if (get_user(c, tmp))
671 return -EFAULT;
672
673 charlcd_write_char(the_charlcd, c);
674 }
675
676 return tmp - buf;
677}
678
679static int charlcd_open(struct inode *inode, struct file *file)
680{
681 struct charlcd_priv *priv = charlcd_to_priv(the_charlcd);
682 int ret;
683
684 ret = -EBUSY;
685 if (!atomic_dec_and_test(&charlcd_available))
686 goto fail; /* open only once at a time */
687
688 ret = -EPERM;
689 if (file->f_mode & FMODE_READ) /* device is write-only */
690 goto fail;
691
692 if (priv->must_clear) {
693 charlcd_clear_display(&priv->lcd);
694 priv->must_clear = false;
695 }
696 return nonseekable_open(inode, file);
697
698 fail:
699 atomic_inc(&charlcd_available);
700 return ret;
701}
702
703static int charlcd_release(struct inode *inode, struct file *file)
704{
705 atomic_inc(&charlcd_available);
706 return 0;
707}
708
709static const struct file_operations charlcd_fops = {
710 .write = charlcd_write,
711 .open = charlcd_open,
712 .release = charlcd_release,
713 .llseek = no_llseek,
714};
715
716static struct miscdevice charlcd_dev = {
717 .minor = LCD_MINOR,
718 .name = "lcd",
719 .fops = &charlcd_fops,
720};
721
722static void charlcd_puts(struct charlcd *lcd, const char *s)
723{
724 const char *tmp = s;
725 int count = strlen(s);
726
727 for (; count-- > 0; tmp++) {
728 if (!in_interrupt() && (((count + 1) & 0x1f) == 0))
729 /*
730 * let's be a little nice with other processes
731 * that need some CPU
732 */
733 schedule();
734
735 charlcd_write_char(lcd, *tmp);
736 }
737}
738
739#ifdef CONFIG_PANEL_BOOT_MESSAGE
740#define LCD_INIT_TEXT CONFIG_PANEL_BOOT_MESSAGE
741#else
742#define LCD_INIT_TEXT "Linux-" UTS_RELEASE "\n"
743#endif
744
745#ifdef CONFIG_CHARLCD_BL_ON
746#define LCD_INIT_BL "\x1b[L+"
747#elif defined(CONFIG_CHARLCD_BL_FLASH)
748#define LCD_INIT_BL "\x1b[L*"
749#else
750#define LCD_INIT_BL "\x1b[L-"
751#endif
752
753/* initialize the LCD driver */
754static int charlcd_init(struct charlcd *lcd)
755{
756 struct charlcd_priv *priv = charlcd_to_priv(lcd);
757 int ret;
758
759 if (lcd->ops->backlight) {
760 mutex_init(&priv->bl_tempo_lock);
761 INIT_DELAYED_WORK(&priv->bl_work, charlcd_bl_off);
762 }
763
764 /*
765 * before this line, we must NOT send anything to the display.
766 * Since charlcd_init_display() needs to write data, we have to
767 * enable mark the LCD initialized just before.
768 */
769 ret = charlcd_init_display(lcd);
770 if (ret)
771 return ret;
772
773 /* display a short message */
774 charlcd_puts(lcd, "\x1b[Lc\x1b[Lb" LCD_INIT_BL LCD_INIT_TEXT);
775
776 /* clear the display on the next device opening */
777 priv->must_clear = true;
778 charlcd_home(lcd);
779 return 0;
780}
781
782struct charlcd *charlcd_alloc(unsigned int drvdata_size)
783{
784 struct charlcd_priv *priv;
785 struct charlcd *lcd;
786
787 priv = kzalloc(sizeof(*priv) + drvdata_size, GFP_KERNEL);
788 if (!priv)
789 return NULL;
790
791 priv->esc_seq.len = -1;
792
793 lcd = &priv->lcd;
794 lcd->ifwidth = 8;
795 lcd->bwidth = DEFAULT_LCD_BWIDTH;
796 lcd->hwidth = DEFAULT_LCD_HWIDTH;
797 lcd->drvdata = priv->drvdata;
798
799 return lcd;
800}
801EXPORT_SYMBOL_GPL(charlcd_alloc);
802
803void charlcd_free(struct charlcd *lcd)
804{
805 kfree(charlcd_to_priv(lcd));
806}
807EXPORT_SYMBOL_GPL(charlcd_free);
808
809static int panel_notify_sys(struct notifier_block *this, unsigned long code,
810 void *unused)
811{
812 struct charlcd *lcd = the_charlcd;
813
814 switch (code) {
815 case SYS_DOWN:
816 charlcd_puts(lcd,
817 "\x0cReloading\nSystem...\x1b[Lc\x1b[Lb\x1b[L+");
818 break;
819 case SYS_HALT:
820 charlcd_puts(lcd, "\x0cSystem Halted.\x1b[Lc\x1b[Lb\x1b[L+");
821 break;
822 case SYS_POWER_OFF:
823 charlcd_puts(lcd, "\x0cPower off.\x1b[Lc\x1b[Lb\x1b[L+");
824 break;
825 default:
826 break;
827 }
828 return NOTIFY_DONE;
829}
830
831static struct notifier_block panel_notifier = {
832 panel_notify_sys,
833 NULL,
834 0
835};
836
837int charlcd_register(struct charlcd *lcd)
838{
839 int ret;
840
841 ret = charlcd_init(lcd);
842 if (ret)
843 return ret;
844
845 ret = misc_register(&charlcd_dev);
846 if (ret)
847 return ret;
848
849 the_charlcd = lcd;
850 register_reboot_notifier(&panel_notifier);
851 return 0;
852}
853EXPORT_SYMBOL_GPL(charlcd_register);
854
855int charlcd_unregister(struct charlcd *lcd)
856{
857 struct charlcd_priv *priv = charlcd_to_priv(lcd);
858
859 unregister_reboot_notifier(&panel_notifier);
860 charlcd_puts(lcd, "\x0cLCD driver unloaded.\x1b[Lc\x1b[Lb\x1b[L-");
861 misc_deregister(&charlcd_dev);
862 the_charlcd = NULL;
863 if (lcd->ops->backlight) {
864 cancel_delayed_work_sync(&priv->bl_work);
865 priv->lcd.ops->backlight(&priv->lcd, 0);
866 }
867
868 return 0;
869}
870EXPORT_SYMBOL_GPL(charlcd_unregister);
871
872MODULE_LICENSE("GPL");
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
30struct 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 */
54static atomic_t charlcd_available = ATOMIC_INIT(1);
55
56/* turn the backlight on or off */
57void 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}
69EXPORT_SYMBOL_GPL(charlcd_backlight);
70
71static 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 */
87void 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}
103EXPORT_SYMBOL_GPL(charlcd_poke);
104
105static void charlcd_home(struct charlcd *lcd)
106{
107 lcd->addr.x = 0;
108 lcd->addr.y = 0;
109 lcd->ops->home(lcd);
110}
111
112static 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
128static 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 */
155static 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
195static 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
365static 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
464static struct charlcd *the_charlcd;
465
466static 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
491static 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
517static int charlcd_release(struct inode *inode, struct file *file)
518{
519 atomic_inc(&charlcd_available);
520 return 0;
521}
522
523static const struct file_operations charlcd_fops = {
524 .write = charlcd_write,
525 .open = charlcd_open,
526 .release = charlcd_release,
527 .llseek = no_llseek,
528};
529
530static struct miscdevice charlcd_dev = {
531 .minor = LCD_MINOR,
532 .name = "lcd",
533 .fops = &charlcd_fops,
534};
535
536static 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 */
564static 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
597struct 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}
612EXPORT_SYMBOL_GPL(charlcd_alloc);
613
614void charlcd_free(struct charlcd *lcd)
615{
616 kfree(charlcd_to_priv(lcd));
617}
618EXPORT_SYMBOL_GPL(charlcd_free);
619
620static 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
642static struct notifier_block panel_notifier = {
643 .notifier_call = panel_notify_sys,
644};
645
646int 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}
662EXPORT_SYMBOL_GPL(charlcd_register);
663
664int 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}
679EXPORT_SYMBOL_GPL(charlcd_unregister);
680
681MODULE_LICENSE("GPL");