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 65 struct 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 */ 95 static atomic_t charlcd_available = ATOMIC_INIT(1); 96 97 /* sleeps that many milliseconds with a reschedule */ 98 static void long_sleep(int ms) 99 { 100 schedule_timeout_interruptible(msecs_to_jiffies(ms)); 101 } 102 103 /* turn the backlight on or off */ 104 static 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 } 116 117 static 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 */ 133 void 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 } 149 EXPORT_SYMBOL_GPL(charlcd_poke); 150 151 static 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 } 168 169 static 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 } 177 178 static 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 } 193 194 static 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 */ 210 static 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 } 220 221 static 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 */ 308 static 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 */ 347 348 static 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 } 553 554 static 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 } 653 654 static struct charlcd *the_charlcd; 655 656 static 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 } 678 679 static 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 } 702 703 static int charlcd_release(struct inode *inode, struct file *file) 704 { 705 atomic_inc(&charlcd_available); 706 return 0; 707 } 708 709 static const struct file_operations charlcd_fops = { 710 .write = charlcd_write, 711 .open = charlcd_open, 712 .release = charlcd_release, 713 .llseek = no_llseek, 714 }; 715 716 static struct miscdevice charlcd_dev = { 717 .minor = LCD_MINOR, 718 .name = "lcd", 719 .fops = &charlcd_fops, 720 }; 721 722 static 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 */ 754 static 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 } 781 782 struct 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 } 801 EXPORT_SYMBOL_GPL(charlcd_alloc); 802 803 void charlcd_free(struct charlcd *lcd) 804 { 805 kfree(charlcd_to_priv(lcd)); 806 } 807 EXPORT_SYMBOL_GPL(charlcd_free); 808 809 static 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 } 830 831 static struct notifier_block panel_notifier = { 832 panel_notify_sys, 833 NULL, 834 0 835 }; 836 837 int 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 } 853 EXPORT_SYMBOL_GPL(charlcd_register); 854 855 int 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 } 870 EXPORT_SYMBOL_GPL(charlcd_unregister); 871 872 MODULE_LICENSE("GPL"); 873