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 charlcd_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 */ 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 */ 106 static void charlcd_backlight(struct charlcd *lcd, int on) 107 { 108 struct charlcd_priv *priv = charlcd_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 } 118 119 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 */ 135 void charlcd_poke(struct charlcd *lcd) 136 { 137 struct charlcd_priv *priv = charlcd_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); 152 153 static void charlcd_gotoxy(struct charlcd *lcd) 154 { 155 struct charlcd_priv *priv = charlcd_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 } 170 171 static void charlcd_home(struct charlcd *lcd) 172 { 173 struct charlcd_priv *priv = charlcd_to_priv(lcd); 174 175 priv->addr.x = 0; 176 priv->addr.y = 0; 177 charlcd_gotoxy(lcd); 178 } 179 180 static void charlcd_print(struct charlcd *lcd, char c) 181 { 182 struct charlcd_priv *priv = charlcd_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 } 195 196 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 */ 212 static void charlcd_clear_display(struct charlcd *lcd) 213 { 214 struct charlcd_priv *priv = charlcd_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 } 222 223 static int charlcd_init_display(struct charlcd *lcd) 224 { 225 void (*write_cmd_raw)(struct charlcd *lcd, int cmd); 226 struct charlcd_priv *priv = charlcd_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 */ 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 */ 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 */ 369 370 static inline int handle_lcd_special_code(struct charlcd *lcd) 371 { 372 struct charlcd_priv *priv = charlcd_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 } 580 581 static void charlcd_write_char(struct charlcd *lcd, char c) 582 { 583 struct charlcd_priv *priv = charlcd_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; 682 683 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 } 705 706 static int charlcd_open(struct inode *inode, struct file *file) 707 { 708 struct charlcd_priv *priv = charlcd_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 } 729 730 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 }; 748 749 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 #ifdef CONFIG_PANEL_BOOT_MESSAGE 767 #define LCD_INIT_TEXT CONFIG_PANEL_BOOT_MESSAGE 768 #else 769 #define LCD_INIT_TEXT "Linux-" UTS_RELEASE "\n" 770 #endif 771 772 #ifdef CONFIG_CHARLCD_BL_ON 773 #define LCD_INIT_BL "\x1b[L+" 774 #elif defined(CONFIG_CHARLCD_BL_FLASH) 775 #define LCD_INIT_BL "\x1b[L*" 776 #else 777 #define LCD_INIT_BL "\x1b[L-" 778 #endif 779 780 /* initialize the LCD driver */ 781 static int charlcd_init(struct charlcd *lcd) 782 { 783 struct charlcd_priv *priv = charlcd_to_priv(lcd); 784 int ret; 785 786 if (lcd->ops->backlight) { 787 mutex_init(&priv->bl_tempo_lock); 788 INIT_DELAYED_WORK(&priv->bl_work, charlcd_bl_off); 789 } 790 791 /* 792 * before this line, we must NOT send anything to the display. 793 * Since charlcd_init_display() needs to write data, we have to 794 * enable mark the LCD initialized just before. 795 */ 796 ret = charlcd_init_display(lcd); 797 if (ret) 798 return ret; 799 800 /* display a short message */ 801 charlcd_puts(lcd, "\x1b[Lc\x1b[Lb" LCD_INIT_BL LCD_INIT_TEXT); 802 803 /* clear the display on the next device opening */ 804 priv->must_clear = true; 805 charlcd_home(lcd); 806 return 0; 807 } 808 809 struct charlcd *charlcd_alloc(unsigned int drvdata_size) 810 { 811 struct charlcd_priv *priv; 812 struct charlcd *lcd; 813 814 priv = kzalloc(sizeof(*priv) + drvdata_size, GFP_KERNEL); 815 if (!priv) 816 return NULL; 817 818 priv->esc_seq.len = -1; 819 820 lcd = &priv->lcd; 821 lcd->ifwidth = 8; 822 lcd->bwidth = DEFAULT_LCD_BWIDTH; 823 lcd->hwidth = DEFAULT_LCD_HWIDTH; 824 lcd->drvdata = priv->drvdata; 825 826 return lcd; 827 } 828 EXPORT_SYMBOL_GPL(charlcd_alloc); 829 830 void charlcd_free(struct charlcd *lcd) 831 { 832 kfree(charlcd_to_priv(lcd)); 833 } 834 EXPORT_SYMBOL_GPL(charlcd_free); 835 836 static int panel_notify_sys(struct notifier_block *this, unsigned long code, 837 void *unused) 838 { 839 struct charlcd *lcd = the_charlcd; 840 841 switch (code) { 842 case SYS_DOWN: 843 charlcd_puts(lcd, 844 "\x0cReloading\nSystem...\x1b[Lc\x1b[Lb\x1b[L+"); 845 break; 846 case SYS_HALT: 847 charlcd_puts(lcd, "\x0cSystem Halted.\x1b[Lc\x1b[Lb\x1b[L+"); 848 break; 849 case SYS_POWER_OFF: 850 charlcd_puts(lcd, "\x0cPower off.\x1b[Lc\x1b[Lb\x1b[L+"); 851 break; 852 default: 853 break; 854 } 855 return NOTIFY_DONE; 856 } 857 858 static struct notifier_block panel_notifier = { 859 panel_notify_sys, 860 NULL, 861 0 862 }; 863 864 int charlcd_register(struct charlcd *lcd) 865 { 866 int ret; 867 868 ret = charlcd_init(lcd); 869 if (ret) 870 return ret; 871 872 ret = misc_register(&charlcd_dev); 873 if (ret) 874 return ret; 875 876 the_charlcd = lcd; 877 register_reboot_notifier(&panel_notifier); 878 return 0; 879 } 880 EXPORT_SYMBOL_GPL(charlcd_register); 881 882 int charlcd_unregister(struct charlcd *lcd) 883 { 884 struct charlcd_priv *priv = charlcd_to_priv(lcd); 885 886 unregister_reboot_notifier(&panel_notifier); 887 charlcd_puts(lcd, "\x0cLCD driver unloaded.\x1b[Lc\x1b[Lb\x1b[L-"); 888 misc_deregister(&charlcd_dev); 889 the_charlcd = NULL; 890 if (lcd->ops->backlight) { 891 cancel_delayed_work_sync(&priv->bl_work); 892 priv->lcd.ops->backlight(&priv->lcd, 0); 893 } 894 895 return 0; 896 } 897 EXPORT_SYMBOL_GPL(charlcd_unregister); 898 899 MODULE_LICENSE("GPL"); 900