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 <misc/charlcd.h>
24 
25 #define LCD_MINOR		156
26 
27 #define DEFAULT_LCD_BWIDTH      40
28 #define DEFAULT_LCD_HWIDTH      64
29 
30 /* Keep the backlight on this many seconds for each flash */
31 #define LCD_BL_TEMPO_PERIOD	4
32 
33 #define LCD_FLAG_B		0x0004	/* Blink on */
34 #define LCD_FLAG_C		0x0008	/* Cursor on */
35 #define LCD_FLAG_D		0x0010	/* Display on */
36 #define LCD_FLAG_F		0x0020	/* Large font mode */
37 #define LCD_FLAG_N		0x0040	/* 2-rows mode */
38 #define LCD_FLAG_L		0x0080	/* Backlight enabled */
39 
40 /* LCD commands */
41 #define LCD_CMD_DISPLAY_CLEAR	0x01	/* Clear entire display */
42 
43 #define LCD_CMD_ENTRY_MODE	0x04	/* Set entry mode */
44 #define LCD_CMD_CURSOR_INC	0x02	/* Increment cursor */
45 
46 #define LCD_CMD_DISPLAY_CTRL	0x08	/* Display control */
47 #define LCD_CMD_DISPLAY_ON	0x04	/* Set display on */
48 #define LCD_CMD_CURSOR_ON	0x02	/* Set cursor on */
49 #define LCD_CMD_BLINK_ON	0x01	/* Set blink on */
50 
51 #define LCD_CMD_SHIFT		0x10	/* Shift cursor/display */
52 #define LCD_CMD_DISPLAY_SHIFT	0x08	/* Shift display instead of cursor */
53 #define LCD_CMD_SHIFT_RIGHT	0x04	/* Shift display/cursor to the right */
54 
55 #define LCD_CMD_FUNCTION_SET	0x20	/* Set function */
56 #define LCD_CMD_DATA_LEN_8BITS	0x10	/* Set data length to 8 bits */
57 #define LCD_CMD_TWO_LINES	0x08	/* Set to two display lines */
58 #define LCD_CMD_FONT_5X10_DOTS	0x04	/* Set char font to 5x10 dots */
59 
60 #define LCD_CMD_SET_CGRAM_ADDR	0x40	/* Set char generator RAM address */
61 
62 #define LCD_CMD_SET_DDRAM_ADDR	0x80	/* Set display data RAM address */
63 
64 #define LCD_ESCAPE_LEN		24	/* Max chars for LCD escape command */
65 #define LCD_ESCAPE_CHAR		27	/* Use char 27 for escape command */
66 
67 struct charlcd_priv {
68 	struct charlcd lcd;
69 
70 	struct delayed_work bl_work;
71 	struct mutex bl_tempo_lock;	/* Protects access to bl_tempo */
72 	bool bl_tempo;
73 
74 	bool must_clear;
75 
76 	/* contains the LCD config state */
77 	unsigned long int flags;
78 
79 	/* Contains the LCD X and Y offset */
80 	struct {
81 		unsigned long int x;
82 		unsigned long int y;
83 	} addr;
84 
85 	/* Current escape sequence and it's length or -1 if outside */
86 	struct {
87 		char buf[LCD_ESCAPE_LEN + 1];
88 		int len;
89 	} esc_seq;
90 
91 	unsigned long long drvdata[0];
92 };
93 
94 #define to_priv(p)	container_of(p, struct charlcd_priv, lcd)
95 
96 /* Device single-open policy control */
97 static atomic_t charlcd_available = ATOMIC_INIT(1);
98 
99 /* sleeps that many milliseconds with a reschedule */
long_sleep(int ms)100 static void long_sleep(int ms)
101 {
102 	schedule_timeout_interruptible(msecs_to_jiffies(ms));
103 }
104 
105 /* turn the backlight on or off */
charlcd_backlight(struct charlcd * lcd,int on)106 static void charlcd_backlight(struct charlcd *lcd, int on)
107 {
108 	struct charlcd_priv *priv = to_priv(lcd);
109 
110 	if (!lcd->ops->backlight)
111 		return;
112 
113 	mutex_lock(&priv->bl_tempo_lock);
114 	if (!priv->bl_tempo)
115 		lcd->ops->backlight(lcd, on);
116 	mutex_unlock(&priv->bl_tempo_lock);
117 }
118 
charlcd_bl_off(struct work_struct * work)119 static void charlcd_bl_off(struct work_struct *work)
120 {
121 	struct delayed_work *dwork = to_delayed_work(work);
122 	struct charlcd_priv *priv =
123 		container_of(dwork, struct charlcd_priv, bl_work);
124 
125 	mutex_lock(&priv->bl_tempo_lock);
126 	if (priv->bl_tempo) {
127 		priv->bl_tempo = false;
128 		if (!(priv->flags & LCD_FLAG_L))
129 			priv->lcd.ops->backlight(&priv->lcd, 0);
130 	}
131 	mutex_unlock(&priv->bl_tempo_lock);
132 }
133 
134 /* turn the backlight on for a little while */
charlcd_poke(struct charlcd * lcd)135 void charlcd_poke(struct charlcd *lcd)
136 {
137 	struct charlcd_priv *priv = to_priv(lcd);
138 
139 	if (!lcd->ops->backlight)
140 		return;
141 
142 	cancel_delayed_work_sync(&priv->bl_work);
143 
144 	mutex_lock(&priv->bl_tempo_lock);
145 	if (!priv->bl_tempo && !(priv->flags & LCD_FLAG_L))
146 		lcd->ops->backlight(lcd, 1);
147 	priv->bl_tempo = true;
148 	schedule_delayed_work(&priv->bl_work, LCD_BL_TEMPO_PERIOD * HZ);
149 	mutex_unlock(&priv->bl_tempo_lock);
150 }
151 EXPORT_SYMBOL_GPL(charlcd_poke);
152 
charlcd_gotoxy(struct charlcd * lcd)153 static void charlcd_gotoxy(struct charlcd *lcd)
154 {
155 	struct charlcd_priv *priv = to_priv(lcd);
156 	unsigned int addr;
157 
158 	/*
159 	 * we force the cursor to stay at the end of the
160 	 * line if it wants to go farther
161 	 */
162 	addr = priv->addr.x < lcd->bwidth ? priv->addr.x & (lcd->hwidth - 1)
163 					  : lcd->bwidth - 1;
164 	if (priv->addr.y & 1)
165 		addr += lcd->hwidth;
166 	if (priv->addr.y & 2)
167 		addr += lcd->bwidth;
168 	lcd->ops->write_cmd(lcd, LCD_CMD_SET_DDRAM_ADDR | addr);
169 }
170 
charlcd_home(struct charlcd * lcd)171 static void charlcd_home(struct charlcd *lcd)
172 {
173 	struct charlcd_priv *priv = to_priv(lcd);
174 
175 	priv->addr.x = 0;
176 	priv->addr.y = 0;
177 	charlcd_gotoxy(lcd);
178 }
179 
charlcd_print(struct charlcd * lcd,char c)180 static void charlcd_print(struct charlcd *lcd, char c)
181 {
182 	struct charlcd_priv *priv = to_priv(lcd);
183 
184 	if (priv->addr.x < lcd->bwidth) {
185 		if (lcd->char_conv)
186 			c = lcd->char_conv[(unsigned char)c];
187 		lcd->ops->write_data(lcd, c);
188 		priv->addr.x++;
189 
190 		/* prevents the cursor from wrapping onto the next line */
191 		if (priv->addr.x == lcd->bwidth)
192 			charlcd_gotoxy(lcd);
193 	}
194 }
195 
charlcd_clear_fast(struct charlcd * lcd)196 static void charlcd_clear_fast(struct charlcd *lcd)
197 {
198 	int pos;
199 
200 	charlcd_home(lcd);
201 
202 	if (lcd->ops->clear_fast)
203 		lcd->ops->clear_fast(lcd);
204 	else
205 		for (pos = 0; pos < min(2, lcd->height) * lcd->hwidth; pos++)
206 			lcd->ops->write_data(lcd, ' ');
207 
208 	charlcd_home(lcd);
209 }
210 
211 /* clears the display and resets X/Y */
charlcd_clear_display(struct charlcd * lcd)212 static void charlcd_clear_display(struct charlcd *lcd)
213 {
214 	struct charlcd_priv *priv = to_priv(lcd);
215 
216 	lcd->ops->write_cmd(lcd, LCD_CMD_DISPLAY_CLEAR);
217 	priv->addr.x = 0;
218 	priv->addr.y = 0;
219 	/* we must wait a few milliseconds (15) */
220 	long_sleep(15);
221 }
222 
charlcd_init_display(struct charlcd * lcd)223 static int charlcd_init_display(struct charlcd *lcd)
224 {
225 	void (*write_cmd_raw)(struct charlcd *lcd, int cmd);
226 	struct charlcd_priv *priv = to_priv(lcd);
227 	u8 init;
228 
229 	if (lcd->ifwidth != 4 && lcd->ifwidth != 8)
230 		return -EINVAL;
231 
232 	priv->flags = ((lcd->height > 1) ? LCD_FLAG_N : 0) | LCD_FLAG_D |
233 		      LCD_FLAG_C | LCD_FLAG_B;
234 
235 	long_sleep(20);		/* wait 20 ms after power-up for the paranoid */
236 
237 	/*
238 	 * 8-bit mode, 1 line, small fonts; let's do it 3 times, to make sure
239 	 * the LCD is in 8-bit mode afterwards
240 	 */
241 	init = LCD_CMD_FUNCTION_SET | LCD_CMD_DATA_LEN_8BITS;
242 	if (lcd->ifwidth == 4) {
243 		init >>= 4;
244 		write_cmd_raw = lcd->ops->write_cmd_raw4;
245 	} else {
246 		write_cmd_raw = lcd->ops->write_cmd;
247 	}
248 	write_cmd_raw(lcd, init);
249 	long_sleep(10);
250 	write_cmd_raw(lcd, init);
251 	long_sleep(10);
252 	write_cmd_raw(lcd, init);
253 	long_sleep(10);
254 
255 	if (lcd->ifwidth == 4) {
256 		/* Switch to 4-bit mode, 1 line, small fonts */
257 		lcd->ops->write_cmd_raw4(lcd, LCD_CMD_FUNCTION_SET >> 4);
258 		long_sleep(10);
259 	}
260 
261 	/* set font height and lines number */
262 	lcd->ops->write_cmd(lcd,
263 		LCD_CMD_FUNCTION_SET |
264 		((lcd->ifwidth == 8) ? LCD_CMD_DATA_LEN_8BITS : 0) |
265 		((priv->flags & LCD_FLAG_F) ? LCD_CMD_FONT_5X10_DOTS : 0) |
266 		((priv->flags & LCD_FLAG_N) ? LCD_CMD_TWO_LINES : 0));
267 	long_sleep(10);
268 
269 	/* display off, cursor off, blink off */
270 	lcd->ops->write_cmd(lcd, LCD_CMD_DISPLAY_CTRL);
271 	long_sleep(10);
272 
273 	lcd->ops->write_cmd(lcd,
274 		LCD_CMD_DISPLAY_CTRL |	/* set display mode */
275 		((priv->flags & LCD_FLAG_D) ? LCD_CMD_DISPLAY_ON : 0) |
276 		((priv->flags & LCD_FLAG_C) ? LCD_CMD_CURSOR_ON : 0) |
277 		((priv->flags & LCD_FLAG_B) ? LCD_CMD_BLINK_ON : 0));
278 
279 	charlcd_backlight(lcd, (priv->flags & LCD_FLAG_L) ? 1 : 0);
280 
281 	long_sleep(10);
282 
283 	/* entry mode set : increment, cursor shifting */
284 	lcd->ops->write_cmd(lcd, LCD_CMD_ENTRY_MODE | LCD_CMD_CURSOR_INC);
285 
286 	charlcd_clear_display(lcd);
287 	return 0;
288 }
289 
290 /*
291  * Parses an unsigned integer from a string, until a non-digit character
292  * is found. The empty string is not accepted. No overflow checks are done.
293  *
294  * Returns whether the parsing was successful. Only in that case
295  * the output parameters are written to.
296  *
297  * TODO: If the kernel adds an inplace version of kstrtoul(), this function
298  * could be easily replaced by that.
299  */
parse_n(const char * s,unsigned long * res,const char ** next_s)300 static bool parse_n(const char *s, unsigned long *res, const char **next_s)
301 {
302 	if (!isdigit(*s))
303 		return false;
304 
305 	*res = 0;
306 	while (isdigit(*s)) {
307 		*res = *res * 10 + (*s - '0');
308 		++s;
309 	}
310 
311 	*next_s = s;
312 	return true;
313 }
314 
315 /*
316  * Parses a movement command of the form "(.*);", where the group can be
317  * any number of subcommands of the form "(x|y)[0-9]+".
318  *
319  * Returns whether the command is valid. The position arguments are
320  * only written if the parsing was successful.
321  *
322  * For instance:
323  *   - ";"          returns (<original x>, <original y>).
324  *   - "x1;"        returns (1, <original y>).
325  *   - "y2x1;"      returns (1, 2).
326  *   - "x12y34x56;" returns (56, 34).
327  *   - ""           fails.
328  *   - "x"          fails.
329  *   - "x;"         fails.
330  *   - "x1"         fails.
331  *   - "xy12;"      fails.
332  *   - "x12yy12;"   fails.
333  *   - "xx"         fails.
334  */
parse_xy(const char * s,unsigned long * x,unsigned long * y)335 static bool parse_xy(const char *s, unsigned long *x, unsigned long *y)
336 {
337 	unsigned long new_x = *x;
338 	unsigned long new_y = *y;
339 
340 	for (;;) {
341 		if (!*s)
342 			return false;
343 
344 		if (*s == ';')
345 			break;
346 
347 		if (*s == 'x') {
348 			if (!parse_n(s + 1, &new_x, &s))
349 				return false;
350 		} else if (*s == 'y') {
351 			if (!parse_n(s + 1, &new_y, &s))
352 				return false;
353 		} else {
354 			return false;
355 		}
356 	}
357 
358 	*x = new_x;
359 	*y = new_y;
360 	return true;
361 }
362 
363 /*
364  * These are the file operation function for user access to /dev/lcd
365  * This function can also be called from inside the kernel, by
366  * setting file and ppos to NULL.
367  *
368  */
369 
handle_lcd_special_code(struct charlcd * lcd)370 static inline int handle_lcd_special_code(struct charlcd *lcd)
371 {
372 	struct charlcd_priv *priv = to_priv(lcd);
373 
374 	/* LCD special codes */
375 
376 	int processed = 0;
377 
378 	char *esc = priv->esc_seq.buf + 2;
379 	int oldflags = priv->flags;
380 
381 	/* check for display mode flags */
382 	switch (*esc) {
383 	case 'D':	/* Display ON */
384 		priv->flags |= LCD_FLAG_D;
385 		processed = 1;
386 		break;
387 	case 'd':	/* Display OFF */
388 		priv->flags &= ~LCD_FLAG_D;
389 		processed = 1;
390 		break;
391 	case 'C':	/* Cursor ON */
392 		priv->flags |= LCD_FLAG_C;
393 		processed = 1;
394 		break;
395 	case 'c':	/* Cursor OFF */
396 		priv->flags &= ~LCD_FLAG_C;
397 		processed = 1;
398 		break;
399 	case 'B':	/* Blink ON */
400 		priv->flags |= LCD_FLAG_B;
401 		processed = 1;
402 		break;
403 	case 'b':	/* Blink OFF */
404 		priv->flags &= ~LCD_FLAG_B;
405 		processed = 1;
406 		break;
407 	case '+':	/* Back light ON */
408 		priv->flags |= LCD_FLAG_L;
409 		processed = 1;
410 		break;
411 	case '-':	/* Back light OFF */
412 		priv->flags &= ~LCD_FLAG_L;
413 		processed = 1;
414 		break;
415 	case '*':	/* Flash back light */
416 		charlcd_poke(lcd);
417 		processed = 1;
418 		break;
419 	case 'f':	/* Small Font */
420 		priv->flags &= ~LCD_FLAG_F;
421 		processed = 1;
422 		break;
423 	case 'F':	/* Large Font */
424 		priv->flags |= LCD_FLAG_F;
425 		processed = 1;
426 		break;
427 	case 'n':	/* One Line */
428 		priv->flags &= ~LCD_FLAG_N;
429 		processed = 1;
430 		break;
431 	case 'N':	/* Two Lines */
432 		priv->flags |= LCD_FLAG_N;
433 		processed = 1;
434 		break;
435 	case 'l':	/* Shift Cursor Left */
436 		if (priv->addr.x > 0) {
437 			/* back one char if not at end of line */
438 			if (priv->addr.x < lcd->bwidth)
439 				lcd->ops->write_cmd(lcd, LCD_CMD_SHIFT);
440 			priv->addr.x--;
441 		}
442 		processed = 1;
443 		break;
444 	case 'r':	/* shift cursor right */
445 		if (priv->addr.x < lcd->width) {
446 			/* allow the cursor to pass the end of the line */
447 			if (priv->addr.x < (lcd->bwidth - 1))
448 				lcd->ops->write_cmd(lcd,
449 					LCD_CMD_SHIFT | LCD_CMD_SHIFT_RIGHT);
450 			priv->addr.x++;
451 		}
452 		processed = 1;
453 		break;
454 	case 'L':	/* shift display left */
455 		lcd->ops->write_cmd(lcd, LCD_CMD_SHIFT | LCD_CMD_DISPLAY_SHIFT);
456 		processed = 1;
457 		break;
458 	case 'R':	/* shift display right */
459 		lcd->ops->write_cmd(lcd,
460 				    LCD_CMD_SHIFT | LCD_CMD_DISPLAY_SHIFT |
461 				    LCD_CMD_SHIFT_RIGHT);
462 		processed = 1;
463 		break;
464 	case 'k': {	/* kill end of line */
465 		int x;
466 
467 		for (x = priv->addr.x; x < lcd->bwidth; x++)
468 			lcd->ops->write_data(lcd, ' ');
469 
470 		/* restore cursor position */
471 		charlcd_gotoxy(lcd);
472 		processed = 1;
473 		break;
474 	}
475 	case 'I':	/* reinitialize display */
476 		charlcd_init_display(lcd);
477 		processed = 1;
478 		break;
479 	case 'G': {
480 		/* Generator : LGcxxxxx...xx; must have <c> between '0'
481 		 * and '7', representing the numerical ASCII code of the
482 		 * redefined character, and <xx...xx> a sequence of 16
483 		 * hex digits representing 8 bytes for each character.
484 		 * Most LCDs will only use 5 lower bits of the 7 first
485 		 * bytes.
486 		 */
487 
488 		unsigned char cgbytes[8];
489 		unsigned char cgaddr;
490 		int cgoffset;
491 		int shift;
492 		char value;
493 		int addr;
494 
495 		if (!strchr(esc, ';'))
496 			break;
497 
498 		esc++;
499 
500 		cgaddr = *(esc++) - '0';
501 		if (cgaddr > 7) {
502 			processed = 1;
503 			break;
504 		}
505 
506 		cgoffset = 0;
507 		shift = 0;
508 		value = 0;
509 		while (*esc && cgoffset < 8) {
510 			shift ^= 4;
511 			if (*esc >= '0' && *esc <= '9') {
512 				value |= (*esc - '0') << shift;
513 			} else if (*esc >= 'A' && *esc <= 'F') {
514 				value |= (*esc - 'A' + 10) << shift;
515 			} else if (*esc >= 'a' && *esc <= 'f') {
516 				value |= (*esc - 'a' + 10) << shift;
517 			} else {
518 				esc++;
519 				continue;
520 			}
521 
522 			if (shift == 0) {
523 				cgbytes[cgoffset++] = value;
524 				value = 0;
525 			}
526 
527 			esc++;
528 		}
529 
530 		lcd->ops->write_cmd(lcd, LCD_CMD_SET_CGRAM_ADDR | (cgaddr * 8));
531 		for (addr = 0; addr < cgoffset; addr++)
532 			lcd->ops->write_data(lcd, cgbytes[addr]);
533 
534 		/* ensures that we stop writing to CGRAM */
535 		charlcd_gotoxy(lcd);
536 		processed = 1;
537 		break;
538 	}
539 	case 'x':	/* gotoxy : LxXXX[yYYY]; */
540 	case 'y':	/* gotoxy : LyYYY[xXXX]; */
541 		if (priv->esc_seq.buf[priv->esc_seq.len - 1] != ';')
542 			break;
543 
544 		/* If the command is valid, move to the new address */
545 		if (parse_xy(esc, &priv->addr.x, &priv->addr.y))
546 			charlcd_gotoxy(lcd);
547 
548 		/* Regardless of its validity, mark as processed */
549 		processed = 1;
550 		break;
551 	}
552 
553 	/* TODO: This indent party here got ugly, clean it! */
554 	/* Check whether one flag was changed */
555 	if (oldflags == priv->flags)
556 		return processed;
557 
558 	/* check whether one of B,C,D flags were changed */
559 	if ((oldflags ^ priv->flags) &
560 	    (LCD_FLAG_B | LCD_FLAG_C | LCD_FLAG_D))
561 		/* set display mode */
562 		lcd->ops->write_cmd(lcd,
563 			LCD_CMD_DISPLAY_CTRL |
564 			((priv->flags & LCD_FLAG_D) ? LCD_CMD_DISPLAY_ON : 0) |
565 			((priv->flags & LCD_FLAG_C) ? LCD_CMD_CURSOR_ON : 0) |
566 			((priv->flags & LCD_FLAG_B) ? LCD_CMD_BLINK_ON : 0));
567 	/* check whether one of F,N flags was changed */
568 	else if ((oldflags ^ priv->flags) & (LCD_FLAG_F | LCD_FLAG_N))
569 		lcd->ops->write_cmd(lcd,
570 			LCD_CMD_FUNCTION_SET |
571 			((lcd->ifwidth == 8) ? LCD_CMD_DATA_LEN_8BITS : 0) |
572 			((priv->flags & LCD_FLAG_F) ? LCD_CMD_FONT_5X10_DOTS : 0) |
573 			((priv->flags & LCD_FLAG_N) ? LCD_CMD_TWO_LINES : 0));
574 	/* check whether L flag was changed */
575 	else if ((oldflags ^ priv->flags) & LCD_FLAG_L)
576 		charlcd_backlight(lcd, !!(priv->flags & LCD_FLAG_L));
577 
578 	return processed;
579 }
580 
charlcd_write_char(struct charlcd * lcd,char c)581 static void charlcd_write_char(struct charlcd *lcd, char c)
582 {
583 	struct charlcd_priv *priv = to_priv(lcd);
584 
585 	/* first, we'll test if we're in escape mode */
586 	if ((c != '\n') && priv->esc_seq.len >= 0) {
587 		/* yes, let's add this char to the buffer */
588 		priv->esc_seq.buf[priv->esc_seq.len++] = c;
589 		priv->esc_seq.buf[priv->esc_seq.len] = '\0';
590 	} else {
591 		/* aborts any previous escape sequence */
592 		priv->esc_seq.len = -1;
593 
594 		switch (c) {
595 		case LCD_ESCAPE_CHAR:
596 			/* start of an escape sequence */
597 			priv->esc_seq.len = 0;
598 			priv->esc_seq.buf[priv->esc_seq.len] = '\0';
599 			break;
600 		case '\b':
601 			/* go back one char and clear it */
602 			if (priv->addr.x > 0) {
603 				/*
604 				 * check if we're not at the
605 				 * end of the line
606 				 */
607 				if (priv->addr.x < lcd->bwidth)
608 					/* back one char */
609 					lcd->ops->write_cmd(lcd, LCD_CMD_SHIFT);
610 				priv->addr.x--;
611 			}
612 			/* replace with a space */
613 			lcd->ops->write_data(lcd, ' ');
614 			/* back one char again */
615 			lcd->ops->write_cmd(lcd, LCD_CMD_SHIFT);
616 			break;
617 		case '\f':
618 			/* quickly clear the display */
619 			charlcd_clear_fast(lcd);
620 			break;
621 		case '\n':
622 			/*
623 			 * flush the remainder of the current line and
624 			 * go to the beginning of the next line
625 			 */
626 			for (; priv->addr.x < lcd->bwidth; priv->addr.x++)
627 				lcd->ops->write_data(lcd, ' ');
628 			priv->addr.x = 0;
629 			priv->addr.y = (priv->addr.y + 1) % lcd->height;
630 			charlcd_gotoxy(lcd);
631 			break;
632 		case '\r':
633 			/* go to the beginning of the same line */
634 			priv->addr.x = 0;
635 			charlcd_gotoxy(lcd);
636 			break;
637 		case '\t':
638 			/* print a space instead of the tab */
639 			charlcd_print(lcd, ' ');
640 			break;
641 		default:
642 			/* simply print this char */
643 			charlcd_print(lcd, c);
644 			break;
645 		}
646 	}
647 
648 	/*
649 	 * now we'll see if we're in an escape mode and if the current
650 	 * escape sequence can be understood.
651 	 */
652 	if (priv->esc_seq.len >= 2) {
653 		int processed = 0;
654 
655 		if (!strcmp(priv->esc_seq.buf, "[2J")) {
656 			/* clear the display */
657 			charlcd_clear_fast(lcd);
658 			processed = 1;
659 		} else if (!strcmp(priv->esc_seq.buf, "[H")) {
660 			/* cursor to home */
661 			charlcd_home(lcd);
662 			processed = 1;
663 		}
664 		/* codes starting with ^[[L */
665 		else if ((priv->esc_seq.len >= 3) &&
666 			 (priv->esc_seq.buf[0] == '[') &&
667 			 (priv->esc_seq.buf[1] == 'L')) {
668 			processed = handle_lcd_special_code(lcd);
669 		}
670 
671 		/* LCD special escape codes */
672 		/*
673 		 * flush the escape sequence if it's been processed
674 		 * or if it is getting too long.
675 		 */
676 		if (processed || (priv->esc_seq.len >= LCD_ESCAPE_LEN))
677 			priv->esc_seq.len = -1;
678 	} /* escape codes */
679 }
680 
681 static struct charlcd *the_charlcd;
682 
charlcd_write(struct file * file,const char __user * buf,size_t count,loff_t * ppos)683 static ssize_t charlcd_write(struct file *file, const char __user *buf,
684 			     size_t count, loff_t *ppos)
685 {
686 	const char __user *tmp = buf;
687 	char c;
688 
689 	for (; count-- > 0; (*ppos)++, tmp++) {
690 		if (!in_interrupt() && (((count + 1) & 0x1f) == 0))
691 			/*
692 			 * let's be a little nice with other processes
693 			 * that need some CPU
694 			 */
695 			schedule();
696 
697 		if (get_user(c, tmp))
698 			return -EFAULT;
699 
700 		charlcd_write_char(the_charlcd, c);
701 	}
702 
703 	return tmp - buf;
704 }
705 
charlcd_open(struct inode * inode,struct file * file)706 static int charlcd_open(struct inode *inode, struct file *file)
707 {
708 	struct charlcd_priv *priv = to_priv(the_charlcd);
709 	int ret;
710 
711 	ret = -EBUSY;
712 	if (!atomic_dec_and_test(&charlcd_available))
713 		goto fail;	/* open only once at a time */
714 
715 	ret = -EPERM;
716 	if (file->f_mode & FMODE_READ)	/* device is write-only */
717 		goto fail;
718 
719 	if (priv->must_clear) {
720 		charlcd_clear_display(&priv->lcd);
721 		priv->must_clear = false;
722 	}
723 	return nonseekable_open(inode, file);
724 
725  fail:
726 	atomic_inc(&charlcd_available);
727 	return ret;
728 }
729 
charlcd_release(struct inode * inode,struct file * file)730 static int charlcd_release(struct inode *inode, struct file *file)
731 {
732 	atomic_inc(&charlcd_available);
733 	return 0;
734 }
735 
736 static const struct file_operations charlcd_fops = {
737 	.write   = charlcd_write,
738 	.open    = charlcd_open,
739 	.release = charlcd_release,
740 	.llseek  = no_llseek,
741 };
742 
743 static struct miscdevice charlcd_dev = {
744 	.minor	= LCD_MINOR,
745 	.name	= "lcd",
746 	.fops	= &charlcd_fops,
747 };
748 
charlcd_puts(struct charlcd * lcd,const char * s)749 static void charlcd_puts(struct charlcd *lcd, const char *s)
750 {
751 	const char *tmp = s;
752 	int count = strlen(s);
753 
754 	for (; count-- > 0; tmp++) {
755 		if (!in_interrupt() && (((count + 1) & 0x1f) == 0))
756 			/*
757 			 * let's be a little nice with other processes
758 			 * that need some CPU
759 			 */
760 			schedule();
761 
762 		charlcd_write_char(lcd, *tmp);
763 	}
764 }
765 
766 /* initialize the LCD driver */
charlcd_init(struct charlcd * lcd)767 static int charlcd_init(struct charlcd *lcd)
768 {
769 	struct charlcd_priv *priv = to_priv(lcd);
770 	int ret;
771 
772 	if (lcd->ops->backlight) {
773 		mutex_init(&priv->bl_tempo_lock);
774 		INIT_DELAYED_WORK(&priv->bl_work, charlcd_bl_off);
775 	}
776 
777 	/*
778 	 * before this line, we must NOT send anything to the display.
779 	 * Since charlcd_init_display() needs to write data, we have to
780 	 * enable mark the LCD initialized just before.
781 	 */
782 	ret = charlcd_init_display(lcd);
783 	if (ret)
784 		return ret;
785 
786 	/* display a short message */
787 #ifdef CONFIG_PANEL_CHANGE_MESSAGE
788 #ifdef CONFIG_PANEL_BOOT_MESSAGE
789 	charlcd_puts(lcd, "\x1b[Lc\x1b[Lb\x1b[L*" CONFIG_PANEL_BOOT_MESSAGE);
790 #endif
791 #else
792 	charlcd_puts(lcd, "\x1b[Lc\x1b[Lb\x1b[L*Linux-" UTS_RELEASE "\n");
793 #endif
794 	/* clear the display on the next device opening */
795 	priv->must_clear = true;
796 	charlcd_home(lcd);
797 	return 0;
798 }
799 
charlcd_alloc(unsigned int drvdata_size)800 struct charlcd *charlcd_alloc(unsigned int drvdata_size)
801 {
802 	struct charlcd_priv *priv;
803 	struct charlcd *lcd;
804 
805 	priv = kzalloc(sizeof(*priv) + drvdata_size, GFP_KERNEL);
806 	if (!priv)
807 		return NULL;
808 
809 	priv->esc_seq.len = -1;
810 
811 	lcd = &priv->lcd;
812 	lcd->ifwidth = 8;
813 	lcd->bwidth = DEFAULT_LCD_BWIDTH;
814 	lcd->hwidth = DEFAULT_LCD_HWIDTH;
815 	lcd->drvdata = priv->drvdata;
816 
817 	return lcd;
818 }
819 EXPORT_SYMBOL_GPL(charlcd_alloc);
820 
panel_notify_sys(struct notifier_block * this,unsigned long code,void * unused)821 static int panel_notify_sys(struct notifier_block *this, unsigned long code,
822 			    void *unused)
823 {
824 	struct charlcd *lcd = the_charlcd;
825 
826 	switch (code) {
827 	case SYS_DOWN:
828 		charlcd_puts(lcd,
829 			     "\x0cReloading\nSystem...\x1b[Lc\x1b[Lb\x1b[L+");
830 		break;
831 	case SYS_HALT:
832 		charlcd_puts(lcd, "\x0cSystem Halted.\x1b[Lc\x1b[Lb\x1b[L+");
833 		break;
834 	case SYS_POWER_OFF:
835 		charlcd_puts(lcd, "\x0cPower off.\x1b[Lc\x1b[Lb\x1b[L+");
836 		break;
837 	default:
838 		break;
839 	}
840 	return NOTIFY_DONE;
841 }
842 
843 static struct notifier_block panel_notifier = {
844 	panel_notify_sys,
845 	NULL,
846 	0
847 };
848 
charlcd_register(struct charlcd * lcd)849 int charlcd_register(struct charlcd *lcd)
850 {
851 	int ret;
852 
853 	ret = charlcd_init(lcd);
854 	if (ret)
855 		return ret;
856 
857 	ret = misc_register(&charlcd_dev);
858 	if (ret)
859 		return ret;
860 
861 	the_charlcd = lcd;
862 	register_reboot_notifier(&panel_notifier);
863 	return 0;
864 }
865 EXPORT_SYMBOL_GPL(charlcd_register);
866 
charlcd_unregister(struct charlcd * lcd)867 int charlcd_unregister(struct charlcd *lcd)
868 {
869 	struct charlcd_priv *priv = to_priv(lcd);
870 
871 	unregister_reboot_notifier(&panel_notifier);
872 	charlcd_puts(lcd, "\x0cLCD driver unloaded.\x1b[Lc\x1b[Lb\x1b[L-");
873 	misc_deregister(&charlcd_dev);
874 	the_charlcd = NULL;
875 	if (lcd->ops->backlight) {
876 		cancel_delayed_work_sync(&priv->bl_work);
877 		priv->lcd.ops->backlight(&priv->lcd, 0);
878 	}
879 
880 	return 0;
881 }
882 EXPORT_SYMBOL_GPL(charlcd_unregister);
883 
884 MODULE_LICENSE("GPL");
885