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 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 a movement command of the form "(.*);", where the group can be 292 * any number of subcommands of the form "(x|y)[0-9]+". 293 * 294 * Returns whether the command is valid. The position arguments are 295 * only written if the parsing was successful. 296 * 297 * For instance: 298 * - ";" returns (<original x>, <original y>). 299 * - "x1;" returns (1, <original y>). 300 * - "y2x1;" returns (1, 2). 301 * - "x12y34x56;" returns (56, 34). 302 * - "" fails. 303 * - "x" fails. 304 * - "x;" fails. 305 * - "x1" fails. 306 * - "xy12;" fails. 307 * - "x12yy12;" fails. 308 * - "xx" fails. 309 */ 310 static bool parse_xy(const char *s, unsigned long *x, unsigned long *y) 311 { 312 unsigned long new_x = *x; 313 unsigned long new_y = *y; 314 char *p; 315 316 for (;;) { 317 if (!*s) 318 return false; 319 320 if (*s == ';') 321 break; 322 323 if (*s == 'x') { 324 new_x = simple_strtoul(s + 1, &p, 10); 325 if (p == s + 1) 326 return false; 327 s = p; 328 } else if (*s == 'y') { 329 new_y = simple_strtoul(s + 1, &p, 10); 330 if (p == s + 1) 331 return false; 332 s = p; 333 } else { 334 return false; 335 } 336 } 337 338 *x = new_x; 339 *y = new_y; 340 return true; 341 } 342 343 /* 344 * These are the file operation function for user access to /dev/lcd 345 * This function can also be called from inside the kernel, by 346 * setting file and ppos to NULL. 347 * 348 */ 349 350 static inline int handle_lcd_special_code(struct charlcd *lcd) 351 { 352 struct charlcd_priv *priv = charlcd_to_priv(lcd); 353 354 /* LCD special codes */ 355 356 int processed = 0; 357 358 char *esc = priv->esc_seq.buf + 2; 359 int oldflags = priv->flags; 360 361 /* check for display mode flags */ 362 switch (*esc) { 363 case 'D': /* Display ON */ 364 priv->flags |= LCD_FLAG_D; 365 processed = 1; 366 break; 367 case 'd': /* Display OFF */ 368 priv->flags &= ~LCD_FLAG_D; 369 processed = 1; 370 break; 371 case 'C': /* Cursor ON */ 372 priv->flags |= LCD_FLAG_C; 373 processed = 1; 374 break; 375 case 'c': /* Cursor OFF */ 376 priv->flags &= ~LCD_FLAG_C; 377 processed = 1; 378 break; 379 case 'B': /* Blink ON */ 380 priv->flags |= LCD_FLAG_B; 381 processed = 1; 382 break; 383 case 'b': /* Blink OFF */ 384 priv->flags &= ~LCD_FLAG_B; 385 processed = 1; 386 break; 387 case '+': /* Back light ON */ 388 priv->flags |= LCD_FLAG_L; 389 processed = 1; 390 break; 391 case '-': /* Back light OFF */ 392 priv->flags &= ~LCD_FLAG_L; 393 processed = 1; 394 break; 395 case '*': /* Flash back light */ 396 charlcd_poke(lcd); 397 processed = 1; 398 break; 399 case 'f': /* Small Font */ 400 priv->flags &= ~LCD_FLAG_F; 401 processed = 1; 402 break; 403 case 'F': /* Large Font */ 404 priv->flags |= LCD_FLAG_F; 405 processed = 1; 406 break; 407 case 'n': /* One Line */ 408 priv->flags &= ~LCD_FLAG_N; 409 processed = 1; 410 break; 411 case 'N': /* Two Lines */ 412 priv->flags |= LCD_FLAG_N; 413 processed = 1; 414 break; 415 case 'l': /* Shift Cursor Left */ 416 if (priv->addr.x > 0) { 417 /* back one char if not at end of line */ 418 if (priv->addr.x < lcd->bwidth) 419 lcd->ops->write_cmd(lcd, LCD_CMD_SHIFT); 420 priv->addr.x--; 421 } 422 processed = 1; 423 break; 424 case 'r': /* shift cursor right */ 425 if (priv->addr.x < lcd->width) { 426 /* allow the cursor to pass the end of the line */ 427 if (priv->addr.x < (lcd->bwidth - 1)) 428 lcd->ops->write_cmd(lcd, 429 LCD_CMD_SHIFT | LCD_CMD_SHIFT_RIGHT); 430 priv->addr.x++; 431 } 432 processed = 1; 433 break; 434 case 'L': /* shift display left */ 435 lcd->ops->write_cmd(lcd, LCD_CMD_SHIFT | LCD_CMD_DISPLAY_SHIFT); 436 processed = 1; 437 break; 438 case 'R': /* shift display right */ 439 lcd->ops->write_cmd(lcd, 440 LCD_CMD_SHIFT | LCD_CMD_DISPLAY_SHIFT | 441 LCD_CMD_SHIFT_RIGHT); 442 processed = 1; 443 break; 444 case 'k': { /* kill end of line */ 445 int x; 446 447 for (x = priv->addr.x; x < lcd->bwidth; x++) 448 lcd->ops->write_data(lcd, ' '); 449 450 /* restore cursor position */ 451 charlcd_gotoxy(lcd); 452 processed = 1; 453 break; 454 } 455 case 'I': /* reinitialize display */ 456 charlcd_init_display(lcd); 457 processed = 1; 458 break; 459 case 'G': { 460 /* Generator : LGcxxxxx...xx; must have <c> between '0' 461 * and '7', representing the numerical ASCII code of the 462 * redefined character, and <xx...xx> a sequence of 16 463 * hex digits representing 8 bytes for each character. 464 * Most LCDs will only use 5 lower bits of the 7 first 465 * bytes. 466 */ 467 468 unsigned char cgbytes[8]; 469 unsigned char cgaddr; 470 int cgoffset; 471 int shift; 472 char value; 473 int addr; 474 475 if (!strchr(esc, ';')) 476 break; 477 478 esc++; 479 480 cgaddr = *(esc++) - '0'; 481 if (cgaddr > 7) { 482 processed = 1; 483 break; 484 } 485 486 cgoffset = 0; 487 shift = 0; 488 value = 0; 489 while (*esc && cgoffset < 8) { 490 shift ^= 4; 491 if (*esc >= '0' && *esc <= '9') { 492 value |= (*esc - '0') << shift; 493 } else if (*esc >= 'A' && *esc <= 'F') { 494 value |= (*esc - 'A' + 10) << shift; 495 } else if (*esc >= 'a' && *esc <= 'f') { 496 value |= (*esc - 'a' + 10) << shift; 497 } else { 498 esc++; 499 continue; 500 } 501 502 if (shift == 0) { 503 cgbytes[cgoffset++] = value; 504 value = 0; 505 } 506 507 esc++; 508 } 509 510 lcd->ops->write_cmd(lcd, LCD_CMD_SET_CGRAM_ADDR | (cgaddr * 8)); 511 for (addr = 0; addr < cgoffset; addr++) 512 lcd->ops->write_data(lcd, cgbytes[addr]); 513 514 /* ensures that we stop writing to CGRAM */ 515 charlcd_gotoxy(lcd); 516 processed = 1; 517 break; 518 } 519 case 'x': /* gotoxy : LxXXX[yYYY]; */ 520 case 'y': /* gotoxy : LyYYY[xXXX]; */ 521 if (priv->esc_seq.buf[priv->esc_seq.len - 1] != ';') 522 break; 523 524 /* If the command is valid, move to the new address */ 525 if (parse_xy(esc, &priv->addr.x, &priv->addr.y)) 526 charlcd_gotoxy(lcd); 527 528 /* Regardless of its validity, mark as processed */ 529 processed = 1; 530 break; 531 } 532 533 /* TODO: This indent party here got ugly, clean it! */ 534 /* Check whether one flag was changed */ 535 if (oldflags == priv->flags) 536 return processed; 537 538 /* check whether one of B,C,D flags were changed */ 539 if ((oldflags ^ priv->flags) & 540 (LCD_FLAG_B | LCD_FLAG_C | LCD_FLAG_D)) 541 /* set display mode */ 542 lcd->ops->write_cmd(lcd, 543 LCD_CMD_DISPLAY_CTRL | 544 ((priv->flags & LCD_FLAG_D) ? LCD_CMD_DISPLAY_ON : 0) | 545 ((priv->flags & LCD_FLAG_C) ? LCD_CMD_CURSOR_ON : 0) | 546 ((priv->flags & LCD_FLAG_B) ? LCD_CMD_BLINK_ON : 0)); 547 /* check whether one of F,N flags was changed */ 548 else if ((oldflags ^ priv->flags) & (LCD_FLAG_F | LCD_FLAG_N)) 549 lcd->ops->write_cmd(lcd, 550 LCD_CMD_FUNCTION_SET | 551 ((lcd->ifwidth == 8) ? LCD_CMD_DATA_LEN_8BITS : 0) | 552 ((priv->flags & LCD_FLAG_F) ? LCD_CMD_FONT_5X10_DOTS : 0) | 553 ((priv->flags & LCD_FLAG_N) ? LCD_CMD_TWO_LINES : 0)); 554 /* check whether L flag was changed */ 555 else if ((oldflags ^ priv->flags) & LCD_FLAG_L) 556 charlcd_backlight(lcd, !!(priv->flags & LCD_FLAG_L)); 557 558 return processed; 559 } 560 561 static void charlcd_write_char(struct charlcd *lcd, char c) 562 { 563 struct charlcd_priv *priv = charlcd_to_priv(lcd); 564 565 /* first, we'll test if we're in escape mode */ 566 if ((c != '\n') && priv->esc_seq.len >= 0) { 567 /* yes, let's add this char to the buffer */ 568 priv->esc_seq.buf[priv->esc_seq.len++] = c; 569 priv->esc_seq.buf[priv->esc_seq.len] = '\0'; 570 } else { 571 /* aborts any previous escape sequence */ 572 priv->esc_seq.len = -1; 573 574 switch (c) { 575 case LCD_ESCAPE_CHAR: 576 /* start of an escape sequence */ 577 priv->esc_seq.len = 0; 578 priv->esc_seq.buf[priv->esc_seq.len] = '\0'; 579 break; 580 case '\b': 581 /* go back one char and clear it */ 582 if (priv->addr.x > 0) { 583 /* 584 * check if we're not at the 585 * end of the line 586 */ 587 if (priv->addr.x < lcd->bwidth) 588 /* back one char */ 589 lcd->ops->write_cmd(lcd, LCD_CMD_SHIFT); 590 priv->addr.x--; 591 } 592 /* replace with a space */ 593 lcd->ops->write_data(lcd, ' '); 594 /* back one char again */ 595 lcd->ops->write_cmd(lcd, LCD_CMD_SHIFT); 596 break; 597 case '\f': 598 /* quickly clear the display */ 599 charlcd_clear_fast(lcd); 600 break; 601 case '\n': 602 /* 603 * flush the remainder of the current line and 604 * go to the beginning of the next line 605 */ 606 for (; priv->addr.x < lcd->bwidth; priv->addr.x++) 607 lcd->ops->write_data(lcd, ' '); 608 priv->addr.x = 0; 609 priv->addr.y = (priv->addr.y + 1) % lcd->height; 610 charlcd_gotoxy(lcd); 611 break; 612 case '\r': 613 /* go to the beginning of the same line */ 614 priv->addr.x = 0; 615 charlcd_gotoxy(lcd); 616 break; 617 case '\t': 618 /* print a space instead of the tab */ 619 charlcd_print(lcd, ' '); 620 break; 621 default: 622 /* simply print this char */ 623 charlcd_print(lcd, c); 624 break; 625 } 626 } 627 628 /* 629 * now we'll see if we're in an escape mode and if the current 630 * escape sequence can be understood. 631 */ 632 if (priv->esc_seq.len >= 2) { 633 int processed = 0; 634 635 if (!strcmp(priv->esc_seq.buf, "[2J")) { 636 /* clear the display */ 637 charlcd_clear_fast(lcd); 638 processed = 1; 639 } else if (!strcmp(priv->esc_seq.buf, "[H")) { 640 /* cursor to home */ 641 charlcd_home(lcd); 642 processed = 1; 643 } 644 /* codes starting with ^[[L */ 645 else if ((priv->esc_seq.len >= 3) && 646 (priv->esc_seq.buf[0] == '[') && 647 (priv->esc_seq.buf[1] == 'L')) { 648 processed = handle_lcd_special_code(lcd); 649 } 650 651 /* LCD special escape codes */ 652 /* 653 * flush the escape sequence if it's been processed 654 * or if it is getting too long. 655 */ 656 if (processed || (priv->esc_seq.len >= LCD_ESCAPE_LEN)) 657 priv->esc_seq.len = -1; 658 } /* escape codes */ 659 } 660 661 static struct charlcd *the_charlcd; 662 663 static ssize_t charlcd_write(struct file *file, const char __user *buf, 664 size_t count, loff_t *ppos) 665 { 666 const char __user *tmp = buf; 667 char c; 668 669 for (; count-- > 0; (*ppos)++, tmp++) { 670 if (!in_interrupt() && (((count + 1) & 0x1f) == 0)) 671 /* 672 * let's be a little nice with other processes 673 * that need some CPU 674 */ 675 schedule(); 676 677 if (get_user(c, tmp)) 678 return -EFAULT; 679 680 charlcd_write_char(the_charlcd, c); 681 } 682 683 return tmp - buf; 684 } 685 686 static int charlcd_open(struct inode *inode, struct file *file) 687 { 688 struct charlcd_priv *priv = charlcd_to_priv(the_charlcd); 689 int ret; 690 691 ret = -EBUSY; 692 if (!atomic_dec_and_test(&charlcd_available)) 693 goto fail; /* open only once at a time */ 694 695 ret = -EPERM; 696 if (file->f_mode & FMODE_READ) /* device is write-only */ 697 goto fail; 698 699 if (priv->must_clear) { 700 charlcd_clear_display(&priv->lcd); 701 priv->must_clear = false; 702 } 703 return nonseekable_open(inode, file); 704 705 fail: 706 atomic_inc(&charlcd_available); 707 return ret; 708 } 709 710 static int charlcd_release(struct inode *inode, struct file *file) 711 { 712 atomic_inc(&charlcd_available); 713 return 0; 714 } 715 716 static const struct file_operations charlcd_fops = { 717 .write = charlcd_write, 718 .open = charlcd_open, 719 .release = charlcd_release, 720 .llseek = no_llseek, 721 }; 722 723 static struct miscdevice charlcd_dev = { 724 .minor = LCD_MINOR, 725 .name = "lcd", 726 .fops = &charlcd_fops, 727 }; 728 729 static void charlcd_puts(struct charlcd *lcd, const char *s) 730 { 731 const char *tmp = s; 732 int count = strlen(s); 733 734 for (; count-- > 0; tmp++) { 735 if (!in_interrupt() && (((count + 1) & 0x1f) == 0)) 736 /* 737 * let's be a little nice with other processes 738 * that need some CPU 739 */ 740 schedule(); 741 742 charlcd_write_char(lcd, *tmp); 743 } 744 } 745 746 #ifdef CONFIG_PANEL_BOOT_MESSAGE 747 #define LCD_INIT_TEXT CONFIG_PANEL_BOOT_MESSAGE 748 #else 749 #define LCD_INIT_TEXT "Linux-" UTS_RELEASE "\n" 750 #endif 751 752 #ifdef CONFIG_CHARLCD_BL_ON 753 #define LCD_INIT_BL "\x1b[L+" 754 #elif defined(CONFIG_CHARLCD_BL_FLASH) 755 #define LCD_INIT_BL "\x1b[L*" 756 #else 757 #define LCD_INIT_BL "\x1b[L-" 758 #endif 759 760 /* initialize the LCD driver */ 761 static int charlcd_init(struct charlcd *lcd) 762 { 763 struct charlcd_priv *priv = charlcd_to_priv(lcd); 764 int ret; 765 766 if (lcd->ops->backlight) { 767 mutex_init(&priv->bl_tempo_lock); 768 INIT_DELAYED_WORK(&priv->bl_work, charlcd_bl_off); 769 } 770 771 /* 772 * before this line, we must NOT send anything to the display. 773 * Since charlcd_init_display() needs to write data, we have to 774 * enable mark the LCD initialized just before. 775 */ 776 ret = charlcd_init_display(lcd); 777 if (ret) 778 return ret; 779 780 /* display a short message */ 781 charlcd_puts(lcd, "\x1b[Lc\x1b[Lb" LCD_INIT_BL LCD_INIT_TEXT); 782 783 /* clear the display on the next device opening */ 784 priv->must_clear = true; 785 charlcd_home(lcd); 786 return 0; 787 } 788 789 struct charlcd *charlcd_alloc(unsigned int drvdata_size) 790 { 791 struct charlcd_priv *priv; 792 struct charlcd *lcd; 793 794 priv = kzalloc(sizeof(*priv) + drvdata_size, GFP_KERNEL); 795 if (!priv) 796 return NULL; 797 798 priv->esc_seq.len = -1; 799 800 lcd = &priv->lcd; 801 lcd->ifwidth = 8; 802 lcd->bwidth = DEFAULT_LCD_BWIDTH; 803 lcd->hwidth = DEFAULT_LCD_HWIDTH; 804 lcd->drvdata = priv->drvdata; 805 806 return lcd; 807 } 808 EXPORT_SYMBOL_GPL(charlcd_alloc); 809 810 void charlcd_free(struct charlcd *lcd) 811 { 812 kfree(charlcd_to_priv(lcd)); 813 } 814 EXPORT_SYMBOL_GPL(charlcd_free); 815 816 static int panel_notify_sys(struct notifier_block *this, unsigned long code, 817 void *unused) 818 { 819 struct charlcd *lcd = the_charlcd; 820 821 switch (code) { 822 case SYS_DOWN: 823 charlcd_puts(lcd, 824 "\x0cReloading\nSystem...\x1b[Lc\x1b[Lb\x1b[L+"); 825 break; 826 case SYS_HALT: 827 charlcd_puts(lcd, "\x0cSystem Halted.\x1b[Lc\x1b[Lb\x1b[L+"); 828 break; 829 case SYS_POWER_OFF: 830 charlcd_puts(lcd, "\x0cPower off.\x1b[Lc\x1b[Lb\x1b[L+"); 831 break; 832 default: 833 break; 834 } 835 return NOTIFY_DONE; 836 } 837 838 static struct notifier_block panel_notifier = { 839 panel_notify_sys, 840 NULL, 841 0 842 }; 843 844 int charlcd_register(struct charlcd *lcd) 845 { 846 int ret; 847 848 ret = charlcd_init(lcd); 849 if (ret) 850 return ret; 851 852 ret = misc_register(&charlcd_dev); 853 if (ret) 854 return ret; 855 856 the_charlcd = lcd; 857 register_reboot_notifier(&panel_notifier); 858 return 0; 859 } 860 EXPORT_SYMBOL_GPL(charlcd_register); 861 862 int charlcd_unregister(struct charlcd *lcd) 863 { 864 struct charlcd_priv *priv = charlcd_to_priv(lcd); 865 866 unregister_reboot_notifier(&panel_notifier); 867 charlcd_puts(lcd, "\x0cLCD driver unloaded.\x1b[Lc\x1b[Lb\x1b[L-"); 868 misc_deregister(&charlcd_dev); 869 the_charlcd = NULL; 870 if (lcd->ops->backlight) { 871 cancel_delayed_work_sync(&priv->bl_work); 872 priv->lcd.ops->backlight(&priv->lcd, 0); 873 } 874 875 return 0; 876 } 877 EXPORT_SYMBOL_GPL(charlcd_unregister); 878 879 MODULE_LICENSE("GPL"); 880