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 */ 100 static 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 */ 109 static 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 } 121 122 static 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 */ 138 void 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 } 154 EXPORT_SYMBOL_GPL(charlcd_poke); 155 156 static void charlcd_gotoxy(struct charlcd *lcd) 157 { 158 struct charlcd_priv *priv = to_priv(lcd); 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); 172 } 173 174 static 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 } 182 183 static 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++; 192 193 /* prevents the cursor from wrapping onto the next line */ 194 if (priv->addr.x == lcd->bwidth) 195 charlcd_gotoxy(lcd); 196 } 197 } 198 199 static 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 208 for (pos = 0; pos < min(2, lcd->height) * lcd->hwidth; pos++) 209 lcd->ops->write_data(lcd, ' '); 210 211 charlcd_home(lcd); 212 } 213 214 /* clears the display and resets X/Y */ 215 static 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 } 225 226 static int charlcd_init_display(struct charlcd *lcd) 227 { 228 void (*write_cmd_raw)(struct charlcd *lcd, int cmd); 229 struct charlcd_priv *priv = to_priv(lcd); 230 u8 init; 231 232 if (lcd->ifwidth != 4 && lcd->ifwidth != 8) 233 return -EINVAL; 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 */ 239 240 /* 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); 252 long_sleep(10); 253 write_cmd_raw(lcd, init); 254 long_sleep(10); 255 write_cmd_raw(lcd, init); 256 long_sleep(10); 257 258 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 } 263 264 /* set font height and lines number */ 265 lcd->ops->write_cmd(lcd, 266 LCD_CMD_FUNCTION_SET | 267 ((lcd->ifwidth == 8) ? LCD_CMD_DATA_LEN_8BITS : 0) | 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 } 292 293 /* 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 */ 303 static 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 */ 338 static 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 } 365 366 /* 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 */ 372 373 static 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; 436 processed = 1; 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; 516 } else if (*esc >= 'A' && *esc <= 'F') { 517 value |= (*esc - 'A' + 10) << shift; 518 } else if (*esc >= 'a' && *esc <= 'f') { 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]; */ 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 = 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 = 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 /* initialize the LCD driver */ 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 } 799 800 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); 820 821 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 }; 848 849 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); 866 867 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