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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/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#ifndef CONFIG_PANEL_BOOT_MESSAGE
21#include <generated/utsrelease.h>
22#endif
23
24#include "charlcd.h"
25
26/* Keep the backlight on this many seconds for each flash */
27#define LCD_BL_TEMPO_PERIOD 4
28
29#define LCD_ESCAPE_LEN 24 /* Max chars for LCD escape command */
30#define LCD_ESCAPE_CHAR 27 /* Use char 27 for escape command */
31
32struct charlcd_priv {
33 struct charlcd lcd;
34
35 struct delayed_work bl_work;
36 struct mutex bl_tempo_lock; /* Protects access to bl_tempo */
37 bool bl_tempo;
38
39 bool must_clear;
40
41 /* contains the LCD config state */
42 unsigned long flags;
43
44 /* Current escape sequence and it's length or -1 if outside */
45 struct {
46 char buf[LCD_ESCAPE_LEN + 1];
47 int len;
48 } esc_seq;
49
50 unsigned long long drvdata[];
51};
52
53#define charlcd_to_priv(p) container_of(p, struct charlcd_priv, lcd)
54
55/* Device single-open policy control */
56static atomic_t charlcd_available = ATOMIC_INIT(1);
57
58/* turn the backlight on or off */
59void charlcd_backlight(struct charlcd *lcd, enum charlcd_onoff on)
60{
61 struct charlcd_priv *priv = charlcd_to_priv(lcd);
62
63 if (!lcd->ops->backlight)
64 return;
65
66 mutex_lock(&priv->bl_tempo_lock);
67 if (!priv->bl_tempo)
68 lcd->ops->backlight(lcd, on);
69 mutex_unlock(&priv->bl_tempo_lock);
70}
71EXPORT_SYMBOL_GPL(charlcd_backlight);
72
73static void charlcd_bl_off(struct work_struct *work)
74{
75 struct delayed_work *dwork = to_delayed_work(work);
76 struct charlcd_priv *priv =
77 container_of(dwork, struct charlcd_priv, bl_work);
78
79 mutex_lock(&priv->bl_tempo_lock);
80 if (priv->bl_tempo) {
81 priv->bl_tempo = false;
82 if (!(priv->flags & LCD_FLAG_L))
83 priv->lcd.ops->backlight(&priv->lcd, CHARLCD_OFF);
84 }
85 mutex_unlock(&priv->bl_tempo_lock);
86}
87
88/* turn the backlight on for a little while */
89void charlcd_poke(struct charlcd *lcd)
90{
91 struct charlcd_priv *priv = charlcd_to_priv(lcd);
92
93 if (!lcd->ops->backlight)
94 return;
95
96 cancel_delayed_work_sync(&priv->bl_work);
97
98 mutex_lock(&priv->bl_tempo_lock);
99 if (!priv->bl_tempo && !(priv->flags & LCD_FLAG_L))
100 lcd->ops->backlight(lcd, CHARLCD_ON);
101 priv->bl_tempo = true;
102 schedule_delayed_work(&priv->bl_work, LCD_BL_TEMPO_PERIOD * HZ);
103 mutex_unlock(&priv->bl_tempo_lock);
104}
105EXPORT_SYMBOL_GPL(charlcd_poke);
106
107static void charlcd_home(struct charlcd *lcd)
108{
109 lcd->addr.x = 0;
110 lcd->addr.y = 0;
111 lcd->ops->home(lcd);
112}
113
114static void charlcd_print(struct charlcd *lcd, char c)
115{
116 if (lcd->addr.x >= lcd->width)
117 return;
118
119 if (lcd->char_conv)
120 c = lcd->char_conv[(unsigned char)c];
121
122 if (!lcd->ops->print(lcd, c))
123 lcd->addr.x++;
124
125 /* prevents the cursor from wrapping onto the next line */
126 if (lcd->addr.x == lcd->width)
127 lcd->ops->gotoxy(lcd, lcd->addr.x - 1, lcd->addr.y);
128}
129
130static void charlcd_clear_display(struct charlcd *lcd)
131{
132 lcd->ops->clear_display(lcd);
133 lcd->addr.x = 0;
134 lcd->addr.y = 0;
135}
136
137/*
138 * Parses a movement command of the form "(.*);", where the group can be
139 * any number of subcommands of the form "(x|y)[0-9]+".
140 *
141 * Returns whether the command is valid. The position arguments are
142 * only written if the parsing was successful.
143 *
144 * For instance:
145 * - ";" returns (<original x>, <original y>).
146 * - "x1;" returns (1, <original y>).
147 * - "y2x1;" returns (1, 2).
148 * - "x12y34x56;" returns (56, 34).
149 * - "" fails.
150 * - "x" fails.
151 * - "x;" fails.
152 * - "x1" fails.
153 * - "xy12;" fails.
154 * - "x12yy12;" fails.
155 * - "xx" fails.
156 */
157static bool parse_xy(const char *s, unsigned long *x, unsigned long *y)
158{
159 unsigned long new_x = *x;
160 unsigned long new_y = *y;
161 char *p;
162
163 for (;;) {
164 if (!*s)
165 return false;
166
167 if (*s == ';')
168 break;
169
170 if (*s == 'x') {
171 new_x = simple_strtoul(s + 1, &p, 10);
172 if (p == s + 1)
173 return false;
174 s = p;
175 } else if (*s == 'y') {
176 new_y = simple_strtoul(s + 1, &p, 10);
177 if (p == s + 1)
178 return false;
179 s = p;
180 } else {
181 return false;
182 }
183 }
184
185 *x = new_x;
186 *y = new_y;
187 return true;
188}
189
190/*
191 * These are the file operation function for user access to /dev/lcd
192 * This function can also be called from inside the kernel, by
193 * setting file and ppos to NULL.
194 *
195 */
196
197static inline int handle_lcd_special_code(struct charlcd *lcd)
198{
199 struct charlcd_priv *priv = charlcd_to_priv(lcd);
200
201 /* LCD special codes */
202
203 int processed = 0;
204
205 char *esc = priv->esc_seq.buf + 2;
206 int oldflags = priv->flags;
207
208 /* check for display mode flags */
209 switch (*esc) {
210 case 'D': /* Display ON */
211 priv->flags |= LCD_FLAG_D;
212 if (priv->flags != oldflags)
213 lcd->ops->display(lcd, CHARLCD_ON);
214
215 processed = 1;
216 break;
217 case 'd': /* Display OFF */
218 priv->flags &= ~LCD_FLAG_D;
219 if (priv->flags != oldflags)
220 lcd->ops->display(lcd, CHARLCD_OFF);
221
222 processed = 1;
223 break;
224 case 'C': /* Cursor ON */
225 priv->flags |= LCD_FLAG_C;
226 if (priv->flags != oldflags)
227 lcd->ops->cursor(lcd, CHARLCD_ON);
228
229 processed = 1;
230 break;
231 case 'c': /* Cursor OFF */
232 priv->flags &= ~LCD_FLAG_C;
233 if (priv->flags != oldflags)
234 lcd->ops->cursor(lcd, CHARLCD_OFF);
235
236 processed = 1;
237 break;
238 case 'B': /* Blink ON */
239 priv->flags |= LCD_FLAG_B;
240 if (priv->flags != oldflags)
241 lcd->ops->blink(lcd, CHARLCD_ON);
242
243 processed = 1;
244 break;
245 case 'b': /* Blink OFF */
246 priv->flags &= ~LCD_FLAG_B;
247 if (priv->flags != oldflags)
248 lcd->ops->blink(lcd, CHARLCD_OFF);
249
250 processed = 1;
251 break;
252 case '+': /* Back light ON */
253 priv->flags |= LCD_FLAG_L;
254 if (priv->flags != oldflags)
255 charlcd_backlight(lcd, CHARLCD_ON);
256
257 processed = 1;
258 break;
259 case '-': /* Back light OFF */
260 priv->flags &= ~LCD_FLAG_L;
261 if (priv->flags != oldflags)
262 charlcd_backlight(lcd, CHARLCD_OFF);
263
264 processed = 1;
265 break;
266 case '*': /* Flash back light */
267 charlcd_poke(lcd);
268 processed = 1;
269 break;
270 case 'f': /* Small Font */
271 priv->flags &= ~LCD_FLAG_F;
272 if (priv->flags != oldflags)
273 lcd->ops->fontsize(lcd, CHARLCD_FONTSIZE_SMALL);
274
275 processed = 1;
276 break;
277 case 'F': /* Large Font */
278 priv->flags |= LCD_FLAG_F;
279 if (priv->flags != oldflags)
280 lcd->ops->fontsize(lcd, CHARLCD_FONTSIZE_LARGE);
281
282 processed = 1;
283 break;
284 case 'n': /* One Line */
285 priv->flags &= ~LCD_FLAG_N;
286 if (priv->flags != oldflags)
287 lcd->ops->lines(lcd, CHARLCD_LINES_1);
288
289 processed = 1;
290 break;
291 case 'N': /* Two Lines */
292 priv->flags |= LCD_FLAG_N;
293 if (priv->flags != oldflags)
294 lcd->ops->lines(lcd, CHARLCD_LINES_2);
295
296 processed = 1;
297 break;
298 case 'l': /* Shift Cursor Left */
299 if (lcd->addr.x > 0) {
300 if (!lcd->ops->shift_cursor(lcd, CHARLCD_SHIFT_LEFT))
301 lcd->addr.x--;
302 }
303
304 processed = 1;
305 break;
306 case 'r': /* shift cursor right */
307 if (lcd->addr.x < lcd->width) {
308 if (!lcd->ops->shift_cursor(lcd, CHARLCD_SHIFT_RIGHT))
309 lcd->addr.x++;
310 }
311
312 processed = 1;
313 break;
314 case 'L': /* shift display left */
315 lcd->ops->shift_display(lcd, CHARLCD_SHIFT_LEFT);
316 processed = 1;
317 break;
318 case 'R': /* shift display right */
319 lcd->ops->shift_display(lcd, CHARLCD_SHIFT_RIGHT);
320 processed = 1;
321 break;
322 case 'k': { /* kill end of line */
323 int x, xs, ys;
324
325 xs = lcd->addr.x;
326 ys = lcd->addr.y;
327 for (x = lcd->addr.x; x < lcd->width; x++)
328 lcd->ops->print(lcd, ' ');
329
330 /* restore cursor position */
331 lcd->addr.x = xs;
332 lcd->addr.y = ys;
333 lcd->ops->gotoxy(lcd, lcd->addr.x, lcd->addr.y);
334 processed = 1;
335 break;
336 }
337 case 'I': /* reinitialize display */
338 lcd->ops->init_display(lcd);
339 priv->flags = ((lcd->height > 1) ? LCD_FLAG_N : 0) | LCD_FLAG_D |
340 LCD_FLAG_C | LCD_FLAG_B;
341 processed = 1;
342 break;
343 case 'G':
344 if (lcd->ops->redefine_char)
345 processed = lcd->ops->redefine_char(lcd, esc);
346 else
347 processed = 1;
348 break;
349
350 case 'x': /* gotoxy : LxXXX[yYYY]; */
351 case 'y': /* gotoxy : LyYYY[xXXX]; */
352 if (priv->esc_seq.buf[priv->esc_seq.len - 1] != ';')
353 break;
354
355 /* If the command is valid, move to the new address */
356 if (parse_xy(esc, &lcd->addr.x, &lcd->addr.y))
357 lcd->ops->gotoxy(lcd, lcd->addr.x, lcd->addr.y);
358
359 /* Regardless of its validity, mark as processed */
360 processed = 1;
361 break;
362 }
363
364 return processed;
365}
366
367static void charlcd_write_char(struct charlcd *lcd, char c)
368{
369 struct charlcd_priv *priv = charlcd_to_priv(lcd);
370
371 /* first, we'll test if we're in escape mode */
372 if ((c != '\n') && priv->esc_seq.len >= 0) {
373 /* yes, let's add this char to the buffer */
374 priv->esc_seq.buf[priv->esc_seq.len++] = c;
375 priv->esc_seq.buf[priv->esc_seq.len] = '\0';
376 } else {
377 /* aborts any previous escape sequence */
378 priv->esc_seq.len = -1;
379
380 switch (c) {
381 case LCD_ESCAPE_CHAR:
382 /* start of an escape sequence */
383 priv->esc_seq.len = 0;
384 priv->esc_seq.buf[priv->esc_seq.len] = '\0';
385 break;
386 case '\b':
387 /* go back one char and clear it */
388 if (lcd->addr.x > 0) {
389 /* back one char */
390 if (!lcd->ops->shift_cursor(lcd,
391 CHARLCD_SHIFT_LEFT))
392 lcd->addr.x--;
393 }
394 /* replace with a space */
395 charlcd_print(lcd, ' ');
396 /* back one char again */
397 if (!lcd->ops->shift_cursor(lcd, CHARLCD_SHIFT_LEFT))
398 lcd->addr.x--;
399
400 break;
401 case '\f':
402 /* quickly clear the display */
403 charlcd_clear_display(lcd);
404 break;
405 case '\n':
406 /*
407 * flush the remainder of the current line and
408 * go to the beginning of the next line
409 */
410 for (; lcd->addr.x < lcd->width; lcd->addr.x++)
411 lcd->ops->print(lcd, ' ');
412
413 lcd->addr.x = 0;
414 lcd->addr.y = (lcd->addr.y + 1) % lcd->height;
415 lcd->ops->gotoxy(lcd, lcd->addr.x, lcd->addr.y);
416 break;
417 case '\r':
418 /* go to the beginning of the same line */
419 lcd->addr.x = 0;
420 lcd->ops->gotoxy(lcd, lcd->addr.x, lcd->addr.y);
421 break;
422 case '\t':
423 /* print a space instead of the tab */
424 charlcd_print(lcd, ' ');
425 break;
426 default:
427 /* simply print this char */
428 charlcd_print(lcd, c);
429 break;
430 }
431 }
432
433 /*
434 * now we'll see if we're in an escape mode and if the current
435 * escape sequence can be understood.
436 */
437 if (priv->esc_seq.len >= 2) {
438 int processed = 0;
439
440 if (!strcmp(priv->esc_seq.buf, "[2J")) {
441 /* clear the display */
442 charlcd_clear_display(lcd);
443 processed = 1;
444 } else if (!strcmp(priv->esc_seq.buf, "[H")) {
445 /* cursor to home */
446 charlcd_home(lcd);
447 processed = 1;
448 }
449 /* codes starting with ^[[L */
450 else if ((priv->esc_seq.len >= 3) &&
451 (priv->esc_seq.buf[0] == '[') &&
452 (priv->esc_seq.buf[1] == 'L')) {
453 processed = handle_lcd_special_code(lcd);
454 }
455
456 /* LCD special escape codes */
457 /*
458 * flush the escape sequence if it's been processed
459 * or if it is getting too long.
460 */
461 if (processed || (priv->esc_seq.len >= LCD_ESCAPE_LEN))
462 priv->esc_seq.len = -1;
463 } /* escape codes */
464}
465
466static struct charlcd *the_charlcd;
467
468static ssize_t charlcd_write(struct file *file, const char __user *buf,
469 size_t count, loff_t *ppos)
470{
471 const char __user *tmp = buf;
472 char c;
473
474 for (; count-- > 0; (*ppos)++, tmp++) {
475 if (((count + 1) & 0x1f) == 0) {
476 /*
477 * charlcd_write() is invoked as a VFS->write() callback
478 * and as such it is always invoked from preemptible
479 * context and may sleep.
480 */
481 cond_resched();
482 }
483
484 if (get_user(c, tmp))
485 return -EFAULT;
486
487 charlcd_write_char(the_charlcd, c);
488 }
489
490 return tmp - buf;
491}
492
493static int charlcd_open(struct inode *inode, struct file *file)
494{
495 struct charlcd_priv *priv = charlcd_to_priv(the_charlcd);
496 int ret;
497
498 ret = -EBUSY;
499 if (!atomic_dec_and_test(&charlcd_available))
500 goto fail; /* open only once at a time */
501
502 ret = -EPERM;
503 if (file->f_mode & FMODE_READ) /* device is write-only */
504 goto fail;
505
506 if (priv->must_clear) {
507 priv->lcd.ops->clear_display(&priv->lcd);
508 priv->must_clear = false;
509 priv->lcd.addr.x = 0;
510 priv->lcd.addr.y = 0;
511 }
512 return nonseekable_open(inode, file);
513
514 fail:
515 atomic_inc(&charlcd_available);
516 return ret;
517}
518
519static int charlcd_release(struct inode *inode, struct file *file)
520{
521 atomic_inc(&charlcd_available);
522 return 0;
523}
524
525static const struct file_operations charlcd_fops = {
526 .write = charlcd_write,
527 .open = charlcd_open,
528 .release = charlcd_release,
529};
530
531static struct miscdevice charlcd_dev = {
532 .minor = LCD_MINOR,
533 .name = "lcd",
534 .fops = &charlcd_fops,
535};
536
537static void charlcd_puts(struct charlcd *lcd, const char *s)
538{
539 const char *tmp = s;
540 int count = strlen(s);
541
542 for (; count-- > 0; tmp++) {
543 if (((count + 1) & 0x1f) == 0)
544 cond_resched();
545
546 charlcd_write_char(lcd, *tmp);
547 }
548}
549
550#ifdef CONFIG_PANEL_BOOT_MESSAGE
551#define LCD_INIT_TEXT CONFIG_PANEL_BOOT_MESSAGE
552#else
553#define LCD_INIT_TEXT "Linux-" UTS_RELEASE "\n"
554#endif
555
556#ifdef CONFIG_CHARLCD_BL_ON
557#define LCD_INIT_BL "\x1b[L+"
558#elif defined(CONFIG_CHARLCD_BL_FLASH)
559#define LCD_INIT_BL "\x1b[L*"
560#else
561#define LCD_INIT_BL "\x1b[L-"
562#endif
563
564/* initialize the LCD driver */
565static int charlcd_init(struct charlcd *lcd)
566{
567 struct charlcd_priv *priv = charlcd_to_priv(lcd);
568 int ret;
569
570 priv->flags = ((lcd->height > 1) ? LCD_FLAG_N : 0) | LCD_FLAG_D |
571 LCD_FLAG_C | LCD_FLAG_B;
572 if (lcd->ops->backlight) {
573 mutex_init(&priv->bl_tempo_lock);
574 INIT_DELAYED_WORK(&priv->bl_work, charlcd_bl_off);
575 }
576
577 /*
578 * before this line, we must NOT send anything to the display.
579 * Since charlcd_init_display() needs to write data, we have to
580 * enable mark the LCD initialized just before.
581 */
582 if (WARN_ON(!lcd->ops->init_display))
583 return -EINVAL;
584
585 ret = lcd->ops->init_display(lcd);
586 if (ret)
587 return ret;
588
589 /* display a short message */
590 charlcd_puts(lcd, "\x1b[Lc\x1b[Lb" LCD_INIT_BL LCD_INIT_TEXT);
591
592 /* clear the display on the next device opening */
593 priv->must_clear = true;
594 charlcd_home(lcd);
595 return 0;
596}
597
598struct charlcd *charlcd_alloc(void)
599{
600 struct charlcd_priv *priv;
601 struct charlcd *lcd;
602
603 priv = kzalloc(sizeof(*priv), GFP_KERNEL);
604 if (!priv)
605 return NULL;
606
607 priv->esc_seq.len = -1;
608
609 lcd = &priv->lcd;
610
611 return lcd;
612}
613EXPORT_SYMBOL_GPL(charlcd_alloc);
614
615void charlcd_free(struct charlcd *lcd)
616{
617 kfree(charlcd_to_priv(lcd));
618}
619EXPORT_SYMBOL_GPL(charlcd_free);
620
621static int panel_notify_sys(struct notifier_block *this, unsigned long code,
622 void *unused)
623{
624 struct charlcd *lcd = the_charlcd;
625
626 switch (code) {
627 case SYS_DOWN:
628 charlcd_puts(lcd,
629 "\x0cReloading\nSystem...\x1b[Lc\x1b[Lb\x1b[L+");
630 break;
631 case SYS_HALT:
632 charlcd_puts(lcd, "\x0cSystem Halted.\x1b[Lc\x1b[Lb\x1b[L+");
633 break;
634 case SYS_POWER_OFF:
635 charlcd_puts(lcd, "\x0cPower off.\x1b[Lc\x1b[Lb\x1b[L+");
636 break;
637 default:
638 break;
639 }
640 return NOTIFY_DONE;
641}
642
643static struct notifier_block panel_notifier = {
644 .notifier_call = panel_notify_sys,
645};
646
647int charlcd_register(struct charlcd *lcd)
648{
649 int ret;
650
651 ret = charlcd_init(lcd);
652 if (ret)
653 return ret;
654
655 ret = misc_register(&charlcd_dev);
656 if (ret)
657 return ret;
658
659 the_charlcd = lcd;
660 register_reboot_notifier(&panel_notifier);
661 return 0;
662}
663EXPORT_SYMBOL_GPL(charlcd_register);
664
665int charlcd_unregister(struct charlcd *lcd)
666{
667 struct charlcd_priv *priv = charlcd_to_priv(lcd);
668
669 unregister_reboot_notifier(&panel_notifier);
670 charlcd_puts(lcd, "\x0cLCD driver unloaded.\x1b[Lc\x1b[Lb\x1b[L-");
671 misc_deregister(&charlcd_dev);
672 the_charlcd = NULL;
673 if (lcd->ops->backlight) {
674 cancel_delayed_work_sync(&priv->bl_work);
675 priv->lcd.ops->backlight(&priv->lcd, CHARLCD_OFF);
676 }
677
678 return 0;
679}
680EXPORT_SYMBOL_GPL(charlcd_unregister);
681
682MODULE_DESCRIPTION("Character LCD core support");
683MODULE_LICENSE("GPL");