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");
682