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mfd: kempld-core: Constify variables that point to const structure
[linux-2.6-block.git] / drivers / auxdisplay / charlcd.c
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351f683b 1// SPDX-License-Identifier: GPL-2.0+
39f8ea46
GU		 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
39f8ea46
GU		 7 */
8
9#include <linux/atomic.h>
b34050fa 10#include <linux/ctype.h>
39f8ea46
GU		 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
67struct 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 */
97static atomic_t charlcd_available = ATOMIC_INIT(1);
98
99/* sleeps that many milliseconds with a reschedule */
100static void long_sleep(int ms)
101{
102 if (in_interrupt())
103 mdelay(ms);
104 else
105 schedule_timeout_interruptible(msecs_to_jiffies(ms));
106}
107
108/* turn the backlight on or off */
109static void charlcd_backlight(struct charlcd *lcd, int on)
110{
111 struct charlcd_priv *priv = to_priv(lcd);
112
113 if (!lcd->ops->backlight)
114 return;
115
116 mutex_lock(&priv->bl_tempo_lock);
117 if (!priv->bl_tempo)
118 lcd->ops->backlight(lcd, on);
119 mutex_unlock(&priv->bl_tempo_lock);
120}
121
122static void charlcd_bl_off(struct work_struct *work)
123{
124 struct delayed_work *dwork = to_delayed_work(work);
125 struct charlcd_priv *priv =
126 container_of(dwork, struct charlcd_priv, bl_work);
127
128 mutex_lock(&priv->bl_tempo_lock);
129 if (priv->bl_tempo) {
130 priv->bl_tempo = false;
131 if (!(priv->flags & LCD_FLAG_L))
132 priv->lcd.ops->backlight(&priv->lcd, 0);
133 }
134 mutex_unlock(&priv->bl_tempo_lock);
135}
136
137/* turn the backlight on for a little while */
138void charlcd_poke(struct charlcd *lcd)
139{
140 struct charlcd_priv *priv = to_priv(lcd);
141
142 if (!lcd->ops->backlight)
143 return;
144
145 cancel_delayed_work_sync(&priv->bl_work);
146
147 mutex_lock(&priv->bl_tempo_lock);
148 if (!priv->bl_tempo && !(priv->flags & LCD_FLAG_L))
149 lcd->ops->backlight(lcd, 1);
150 priv->bl_tempo = true;
151 schedule_delayed_work(&priv->bl_work, LCD_BL_TEMPO_PERIOD * HZ);
152 mutex_unlock(&priv->bl_tempo_lock);
153}
154EXPORT_SYMBOL_GPL(charlcd_poke);
155
156static void charlcd_gotoxy(struct charlcd *lcd)
157{
158 struct charlcd_priv *priv = to_priv(lcd);
1d3b2af2
GU		 159 unsigned int addr;
160
161 /*
162 * we force the cursor to stay at the end of the
163 * line if it wants to go farther
164 */
165 addr = priv->addr.x < lcd->bwidth ? priv->addr.x & (lcd->hwidth - 1)
166 : lcd->bwidth - 1;
167 if (priv->addr.y & 1)
168 addr += lcd->hwidth;
169 if (priv->addr.y & 2)
170 addr += lcd->bwidth;
171 lcd->ops->write_cmd(lcd, LCD_CMD_SET_DDRAM_ADDR | addr);
39f8ea46
GU		 172}
173
174static void charlcd_home(struct charlcd *lcd)
175{
176 struct charlcd_priv *priv = to_priv(lcd);
177
178 priv->addr.x = 0;
179 priv->addr.y = 0;
180 charlcd_gotoxy(lcd);
181}
182
183static void charlcd_print(struct charlcd *lcd, char c)
184{
185 struct charlcd_priv *priv = to_priv(lcd);
186
187 if (priv->addr.x < lcd->bwidth) {
188 if (lcd->char_conv)
189 c = lcd->char_conv[(unsigned char)c];
190 lcd->ops->write_data(lcd, c);
191 priv->addr.x++;
54bc937f
SY		 192
193 /* prevents the cursor from wrapping onto the next line */
194 if (priv->addr.x == lcd->bwidth)
195 charlcd_gotoxy(lcd);
39f8ea46 196 }
39f8ea46
GU		 197}
198
199static void charlcd_clear_fast(struct charlcd *lcd)
200{
201 int pos;
202
203 charlcd_home(lcd);
204
205 if (lcd->ops->clear_fast)
206 lcd->ops->clear_fast(lcd);
207 else
1d3b2af2 208 for (pos = 0; pos < min(2, lcd->height) * lcd->hwidth; pos++)
39f8ea46
GU		 209 lcd->ops->write_data(lcd, ' ');
210
211 charlcd_home(lcd);
212}
213
214/* clears the display and resets X/Y */
215static void charlcd_clear_display(struct charlcd *lcd)
216{
217 struct charlcd_priv *priv = to_priv(lcd);
218
219 lcd->ops->write_cmd(lcd, LCD_CMD_DISPLAY_CLEAR);
220 priv->addr.x = 0;
221 priv->addr.y = 0;
222 /* we must wait a few milliseconds (15) */
223 long_sleep(15);
224}
225
226static int charlcd_init_display(struct charlcd *lcd)
227{
ac201479 228 void (*write_cmd_raw)(struct charlcd *lcd, int cmd);
39f8ea46 229 struct charlcd_priv *priv = to_priv(lcd);
ac201479
GU		 230 u8 init;
231
232 if (lcd->ifwidth != 4 && lcd->ifwidth != 8)
233 return -EINVAL;
39f8ea46
GU		 234
235 priv->flags = ((lcd->height > 1) ? LCD_FLAG_N : 0) | LCD_FLAG_D |
236 LCD_FLAG_C | LCD_FLAG_B;
237
238 long_sleep(20); /* wait 20 ms after power-up for the paranoid */
239
ac201479
GU		 240 /*
241 * 8-bit mode, 1 line, small fonts; let's do it 3 times, to make sure
242 * the LCD is in 8-bit mode afterwards
243 */
244 init = LCD_CMD_FUNCTION_SET | LCD_CMD_DATA_LEN_8BITS;
245 if (lcd->ifwidth == 4) {
246 init >>= 4;
247 write_cmd_raw = lcd->ops->write_cmd_raw4;
248 } else {
249 write_cmd_raw = lcd->ops->write_cmd;
250 }
251 write_cmd_raw(lcd, init);
39f8ea46 252 long_sleep(10);
ac201479 253 write_cmd_raw(lcd, init);
39f8ea46 254 long_sleep(10);
ac201479 255 write_cmd_raw(lcd, init);
39f8ea46
GU		 256 long_sleep(10);
257
ac201479
GU		 258 if (lcd->ifwidth == 4) {
259 /* Switch to 4-bit mode, 1 line, small fonts */
260 lcd->ops->write_cmd_raw4(lcd, LCD_CMD_FUNCTION_SET >> 4);
261 long_sleep(10);
262 }
263
39f8ea46
GU		 264 /* set font height and lines number */
265 lcd->ops->write_cmd(lcd,
ac201479
GU		 266 LCD_CMD_FUNCTION_SET |
267 ((lcd->ifwidth == 8) ? LCD_CMD_DATA_LEN_8BITS : 0) |
39f8ea46
GU		 268 ((priv->flags & LCD_FLAG_F) ? LCD_CMD_FONT_5X10_DOTS : 0) |
269 ((priv->flags & LCD_FLAG_N) ? LCD_CMD_TWO_LINES : 0));
270 long_sleep(10);
271
272 /* display off, cursor off, blink off */
273 lcd->ops->write_cmd(lcd, LCD_CMD_DISPLAY_CTRL);
274 long_sleep(10);
275
276 lcd->ops->write_cmd(lcd,
277 LCD_CMD_DISPLAY_CTRL | /* set display mode */
278 ((priv->flags & LCD_FLAG_D) ? LCD_CMD_DISPLAY_ON : 0) |
279 ((priv->flags & LCD_FLAG_C) ? LCD_CMD_CURSOR_ON : 0) |
280 ((priv->flags & LCD_FLAG_B) ? LCD_CMD_BLINK_ON : 0));
281
282 charlcd_backlight(lcd, (priv->flags & LCD_FLAG_L) ? 1 : 0);
283
284 long_sleep(10);
285
286 /* entry mode set : increment, cursor shifting */
287 lcd->ops->write_cmd(lcd, LCD_CMD_ENTRY_MODE | LCD_CMD_CURSOR_INC);
288
289 charlcd_clear_display(lcd);
290 return 0;
291}
292
b34050fa
MO		 293/*
294 * Parses an unsigned integer from a string, until a non-digit character
295 * is found. The empty string is not accepted. No overflow checks are done.
296 *
297 * Returns whether the parsing was successful. Only in that case
298 * the output parameters are written to.
299 *
300 * TODO: If the kernel adds an inplace version of kstrtoul(), this function
301 * could be easily replaced by that.
302 */
303static bool parse_n(const char *s, unsigned long *res, const char **next_s)
304{
305 if (!isdigit(*s))
306 return false;
307
308 *res = 0;
309 while (isdigit(*s)) {
310 *res = *res * 10 + (*s - '0');
311 ++s;
312 }
313
314 *next_s = s;
315 return true;
316}
317
318/*
319 * Parses a movement command of the form "(.*);", where the group can be
320 * any number of subcommands of the form "(x|y)[0-9]+".
321 *
322 * Returns whether the command is valid. The position arguments are
323 * only written if the parsing was successful.
324 *
325 * For instance:
326 * - ";" returns (<original x>, <original y>).
327 * - "x1;" returns (1, <original y>).
328 * - "y2x1;" returns (1, 2).
329 * - "x12y34x56;" returns (56, 34).
330 * - "" fails.
331 * - "x" fails.
332 * - "x;" fails.
333 * - "x1" fails.
334 * - "xy12;" fails.
335 * - "x12yy12;" fails.
336 * - "xx" fails.
337 */
338static bool parse_xy(const char *s, unsigned long *x, unsigned long *y)
339{
340 unsigned long new_x = *x;
341 unsigned long new_y = *y;
342
343 for (;;) {
344 if (!*s)
345 return false;
346
347 if (*s == ';')
348 break;
349
350 if (*s == 'x') {
351 if (!parse_n(s + 1, &new_x, &s))
352 return false;
353 } else if (*s == 'y') {
354 if (!parse_n(s + 1, &new_y, &s))
355 return false;
356 } else {
357 return false;
358 }
359 }
360
361 *x = new_x;
362 *y = new_y;
363 return true;
364}
365
39f8ea46
GU		 366/*
367 * These are the file operation function for user access to /dev/lcd
368 * This function can also be called from inside the kernel, by
369 * setting file and ppos to NULL.
370 *
371 */
372
373static inline int handle_lcd_special_code(struct charlcd *lcd)
374{
375 struct charlcd_priv *priv = to_priv(lcd);
376
377 /* LCD special codes */
378
379 int processed = 0;
380
381 char *esc = priv->esc_seq.buf + 2;
382 int oldflags = priv->flags;
383
384 /* check for display mode flags */
385 switch (*esc) {
386 case 'D': /* Display ON */
387 priv->flags |= LCD_FLAG_D;
388 processed = 1;
389 break;
390 case 'd': /* Display OFF */
391 priv->flags &= ~LCD_FLAG_D;
392 processed = 1;
393 break;
394 case 'C': /* Cursor ON */
395 priv->flags |= LCD_FLAG_C;
396 processed = 1;
397 break;
398 case 'c': /* Cursor OFF */
399 priv->flags &= ~LCD_FLAG_C;
400 processed = 1;
401 break;
402 case 'B': /* Blink ON */
403 priv->flags |= LCD_FLAG_B;
404 processed = 1;
405 break;
406 case 'b': /* Blink OFF */
407 priv->flags &= ~LCD_FLAG_B;
408 processed = 1;
409 break;
410 case '+': /* Back light ON */
411 priv->flags |= LCD_FLAG_L;
412 processed = 1;
413 break;
414 case '-': /* Back light OFF */
415 priv->flags &= ~LCD_FLAG_L;
416 processed = 1;
417 break;
418 case '*': /* Flash back light */
419 charlcd_poke(lcd);
420 processed = 1;
421 break;
422 case 'f': /* Small Font */
423 priv->flags &= ~LCD_FLAG_F;
424 processed = 1;
425 break;
426 case 'F': /* Large Font */
427 priv->flags |= LCD_FLAG_F;
428 processed = 1;
429 break;
430 case 'n': /* One Line */
431 priv->flags &= ~LCD_FLAG_N;
432 processed = 1;
433 break;
434 case 'N': /* Two Lines */
435 priv->flags |= LCD_FLAG_N;
99b9b490 436 processed = 1;
39f8ea46
GU		 437 break;
438 case 'l': /* Shift Cursor Left */
439 if (priv->addr.x > 0) {
440 /* back one char if not at end of line */
441 if (priv->addr.x < lcd->bwidth)
442 lcd->ops->write_cmd(lcd, LCD_CMD_SHIFT);
443 priv->addr.x--;
444 }
445 processed = 1;
446 break;
447 case 'r': /* shift cursor right */
448 if (priv->addr.x < lcd->width) {
449 /* allow the cursor to pass the end of the line */
450 if (priv->addr.x < (lcd->bwidth - 1))
451 lcd->ops->write_cmd(lcd,
452 LCD_CMD_SHIFT | LCD_CMD_SHIFT_RIGHT);
453 priv->addr.x++;
454 }
455 processed = 1;
456 break;
457 case 'L': /* shift display left */
458 lcd->ops->write_cmd(lcd, LCD_CMD_SHIFT | LCD_CMD_DISPLAY_SHIFT);
459 processed = 1;
460 break;
461 case 'R': /* shift display right */
462 lcd->ops->write_cmd(lcd,
463 LCD_CMD_SHIFT | LCD_CMD_DISPLAY_SHIFT |
464 LCD_CMD_SHIFT_RIGHT);
465 processed = 1;
466 break;
467 case 'k': { /* kill end of line */
468 int x;
469
470 for (x = priv->addr.x; x < lcd->bwidth; x++)
471 lcd->ops->write_data(lcd, ' ');
472
473 /* restore cursor position */
474 charlcd_gotoxy(lcd);
475 processed = 1;
476 break;
477 }
478 case 'I': /* reinitialize display */
479 charlcd_init_display(lcd);
480 processed = 1;
481 break;
482 case 'G': {
483 /* Generator : LGcxxxxx...xx; must have <c> between '0'
484 * and '7', representing the numerical ASCII code of the
485 * redefined character, and <xx...xx> a sequence of 16
486 * hex digits representing 8 bytes for each character.
487 * Most LCDs will only use 5 lower bits of the 7 first
488 * bytes.
489 */
490
491 unsigned char cgbytes[8];
492 unsigned char cgaddr;
493 int cgoffset;
494 int shift;
495 char value;
496 int addr;
497
498 if (!strchr(esc, ';'))
499 break;
500
501 esc++;
502
503 cgaddr = *(esc++) - '0';
504 if (cgaddr > 7) {
505 processed = 1;
506 break;
507 }
508
509 cgoffset = 0;
510 shift = 0;
511 value = 0;
512 while (*esc && cgoffset < 8) {
513 shift ^= 4;
514 if (*esc >= '0' && *esc <= '9') {
515 value |= (*esc - '0') << shift;
2e8c04f7 516 } else if (*esc >= 'A' && *esc <= 'F') {
39f8ea46 517 value |= (*esc - 'A' + 10) << shift;
2e8c04f7 518 } else if (*esc >= 'a' && *esc <= 'f') {
39f8ea46
GU		 519 value |= (*esc - 'a' + 10) << shift;
520 } else {
521 esc++;
522 continue;
523 }
524
525 if (shift == 0) {
526 cgbytes[cgoffset++] = value;
527 value = 0;
528 }
529
530 esc++;
531 }
532
533 lcd->ops->write_cmd(lcd, LCD_CMD_SET_CGRAM_ADDR | (cgaddr * 8));
534 for (addr = 0; addr < cgoffset; addr++)
535 lcd->ops->write_data(lcd, cgbytes[addr]);
536
537 /* ensures that we stop writing to CGRAM */
538 charlcd_gotoxy(lcd);
539 processed = 1;
540 break;
541 }
542 case 'x': /* gotoxy : LxXXX[yYYY]; */
543 case 'y': /* gotoxy : LyYYY[xXXX]; */
b34050fa
MO		 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);
39f8ea46 547
b34050fa 548 /* Regardless of its validity, mark as processed */
39f8ea46
GU		 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,
ac201479
GU		 570 LCD_CMD_FUNCTION_SET |
571 ((lcd->ifwidth == 8) ? LCD_CMD_DATA_LEN_8BITS : 0) |
39f8ea46
GU		 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
581static 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;
8c483758 589 priv->esc_seq.buf[priv->esc_seq.len] = '\0';
39f8ea46
GU		 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;
8c483758 598 priv->esc_seq.buf[priv->esc_seq.len] = '\0';
39f8ea46
GU		 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;
9629ccca 617 case '\f':
39f8ea46
GU		 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
681static struct charlcd *the_charlcd;
682
683static 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
706static int charlcd_open(struct inode *inode, struct file *file)
707{
708 struct charlcd_priv *priv = to_priv(the_charlcd);
93dc1774 709 int ret;
39f8ea46 710
93dc1774 711 ret = -EBUSY;
39f8ea46 712 if (!atomic_dec_and_test(&charlcd_available))
93dc1774 713 goto fail; /* open only once at a time */
39f8ea46 714
93dc1774 715 ret = -EPERM;
39f8ea46 716 if (file->f_mode & FMODE_READ) /* device is write-only */
93dc1774 717 goto fail;
39f8ea46
GU		 718
719 if (priv->must_clear) {
720 charlcd_clear_display(&priv->lcd);
721 priv->must_clear = false;
722 }
723 return nonseekable_open(inode, file);
93dc1774
WT		 724
725 fail:
726 atomic_inc(&charlcd_available);
727 return ret;
39f8ea46
GU		 728}
729
730static int charlcd_release(struct inode *inode, struct file *file)
731{
732 atomic_inc(&charlcd_available);
733 return 0;
734}
735
736static const struct file_operations charlcd_fops = {
737 .write = charlcd_write,
738 .open = charlcd_open,
739 .release = charlcd_release,
740 .llseek = no_llseek,
741};
742
743static struct miscdevice charlcd_dev = {
744 .minor = LCD_MINOR,
745 .name = "lcd",
746 .fops = &charlcd_fops,
747};
748
749static 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 */
767static 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
800struct 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;
ac201479 812 lcd->ifwidth = 8;
39f8ea46
GU		 813 lcd->bwidth = DEFAULT_LCD_BWIDTH;
814 lcd->hwidth = DEFAULT_LCD_HWIDTH;
815 lcd->drvdata = priv->drvdata;
816
817 return lcd;
818}
819EXPORT_SYMBOL_GPL(charlcd_alloc);
820
821static 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
843static struct notifier_block panel_notifier = {
844 panel_notify_sys,
845 NULL,
846 0
847};
848
849int 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}
865EXPORT_SYMBOL_GPL(charlcd_register);
866
867int 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}
882EXPORT_SYMBOL_GPL(charlcd_unregister);
883
884MODULE_LICENSE("GPL");
Linux 6.x block layer and io_uring tree(s)