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 #include "hd44780_common.h" 25 26 /* Keep the backlight on this many seconds for each flash */ 27 #define LCD_BL_TEMPO_PERIOD 4 28 29 #define LCD_FLAG_B 0x0004 /* Blink on */ 30 #define LCD_FLAG_C 0x0008 /* Cursor on */ 31 #define LCD_FLAG_D 0x0010 /* Display on */ 32 #define LCD_FLAG_F 0x0020 /* Large font mode */ 33 #define LCD_FLAG_N 0x0040 /* 2-rows mode */ 34 #define LCD_FLAG_L 0x0080 /* Backlight enabled */ 35 36 /* LCD commands */ 37 #define LCD_CMD_DISPLAY_CLEAR 0x01 /* Clear entire display */ 38 39 #define LCD_CMD_ENTRY_MODE 0x04 /* Set entry mode */ 40 #define LCD_CMD_CURSOR_INC 0x02 /* Increment cursor */ 41 42 #define LCD_CMD_DISPLAY_CTRL 0x08 /* Display control */ 43 #define LCD_CMD_DISPLAY_ON 0x04 /* Set display on */ 44 #define LCD_CMD_CURSOR_ON 0x02 /* Set cursor on */ 45 #define LCD_CMD_BLINK_ON 0x01 /* Set blink on */ 46 47 #define LCD_CMD_SHIFT 0x10 /* Shift cursor/display */ 48 #define LCD_CMD_DISPLAY_SHIFT 0x08 /* Shift display instead of cursor */ 49 #define LCD_CMD_SHIFT_RIGHT 0x04 /* Shift display/cursor to the right */ 50 51 #define LCD_CMD_FUNCTION_SET 0x20 /* Set function */ 52 #define LCD_CMD_DATA_LEN_8BITS 0x10 /* Set data length to 8 bits */ 53 #define LCD_CMD_TWO_LINES 0x08 /* Set to two display lines */ 54 #define LCD_CMD_FONT_5X10_DOTS 0x04 /* Set char font to 5x10 dots */ 55 56 #define LCD_CMD_SET_CGRAM_ADDR 0x40 /* Set char generator RAM address */ 57 58 #define LCD_CMD_SET_DDRAM_ADDR 0x80 /* Set display data RAM address */ 59 60 #define LCD_ESCAPE_LEN 24 /* Max chars for LCD escape command */ 61 #define LCD_ESCAPE_CHAR 27 /* Use char 27 for escape command */ 62 63 struct charlcd_priv { 64 struct charlcd lcd; 65 66 struct delayed_work bl_work; 67 struct mutex bl_tempo_lock; /* Protects access to bl_tempo */ 68 bool bl_tempo; 69 70 bool must_clear; 71 72 /* contains the LCD config state */ 73 unsigned long int flags; 74 75 /* Contains the LCD X and Y offset */ 76 struct { 77 unsigned long int x; 78 unsigned long int y; 79 } addr; 80 81 /* Current escape sequence and it's length or -1 if outside */ 82 struct { 83 char buf[LCD_ESCAPE_LEN + 1]; 84 int len; 85 } esc_seq; 86 87 unsigned long long drvdata[]; 88 }; 89 90 #define charlcd_to_priv(p) container_of(p, struct charlcd_priv, lcd) 91 92 /* Device single-open policy control */ 93 static atomic_t charlcd_available = ATOMIC_INIT(1); 94 95 /* sleeps that many milliseconds with a reschedule */ 96 static void long_sleep(int ms) 97 { 98 schedule_timeout_interruptible(msecs_to_jiffies(ms)); 99 } 100 101 /* turn the backlight on or off */ 102 static void charlcd_backlight(struct charlcd *lcd, enum charlcd_onoff on) 103 { 104 struct charlcd_priv *priv = charlcd_to_priv(lcd); 105 106 if (!lcd->ops->backlight) 107 return; 108 109 mutex_lock(&priv->bl_tempo_lock); 110 if (!priv->bl_tempo) 111 lcd->ops->backlight(lcd, on); 112 mutex_unlock(&priv->bl_tempo_lock); 113 } 114 115 static void charlcd_bl_off(struct work_struct *work) 116 { 117 struct delayed_work *dwork = to_delayed_work(work); 118 struct charlcd_priv *priv = 119 container_of(dwork, struct charlcd_priv, bl_work); 120 121 mutex_lock(&priv->bl_tempo_lock); 122 if (priv->bl_tempo) { 123 priv->bl_tempo = false; 124 if (!(priv->flags & LCD_FLAG_L)) 125 priv->lcd.ops->backlight(&priv->lcd, 0); 126 } 127 mutex_unlock(&priv->bl_tempo_lock); 128 } 129 130 /* turn the backlight on for a little while */ 131 void charlcd_poke(struct charlcd *lcd) 132 { 133 struct charlcd_priv *priv = charlcd_to_priv(lcd); 134 135 if (!lcd->ops->backlight) 136 return; 137 138 cancel_delayed_work_sync(&priv->bl_work); 139 140 mutex_lock(&priv->bl_tempo_lock); 141 if (!priv->bl_tempo && !(priv->flags & LCD_FLAG_L)) 142 lcd->ops->backlight(lcd, 1); 143 priv->bl_tempo = true; 144 schedule_delayed_work(&priv->bl_work, LCD_BL_TEMPO_PERIOD * HZ); 145 mutex_unlock(&priv->bl_tempo_lock); 146 } 147 EXPORT_SYMBOL_GPL(charlcd_poke); 148 149 static void charlcd_gotoxy(struct charlcd *lcd) 150 { 151 struct charlcd_priv *priv = charlcd_to_priv(lcd); 152 struct hd44780_common *hdc = lcd->drvdata; 153 unsigned int addr; 154 155 /* 156 * we force the cursor to stay at the end of the 157 * line if it wants to go farther 158 */ 159 addr = priv->addr.x < hdc->bwidth ? priv->addr.x & (hdc->hwidth - 1) 160 : hdc->bwidth - 1; 161 if (priv->addr.y & 1) 162 addr += hdc->hwidth; 163 if (priv->addr.y & 2) 164 addr += hdc->bwidth; 165 hdc->write_cmd(hdc, LCD_CMD_SET_DDRAM_ADDR | addr); 166 } 167 168 static void charlcd_home(struct charlcd *lcd) 169 { 170 struct charlcd_priv *priv = charlcd_to_priv(lcd); 171 172 priv->addr.x = 0; 173 priv->addr.y = 0; 174 charlcd_gotoxy(lcd); 175 } 176 177 static void charlcd_print(struct charlcd *lcd, char c) 178 { 179 struct charlcd_priv *priv = charlcd_to_priv(lcd); 180 struct hd44780_common *hdc = lcd->drvdata; 181 182 if (priv->addr.x < hdc->bwidth) { 183 if (lcd->char_conv) 184 c = lcd->char_conv[(unsigned char)c]; 185 hdc->write_data(hdc, c); 186 priv->addr.x++; 187 188 /* prevents the cursor from wrapping onto the next line */ 189 if (priv->addr.x == hdc->bwidth) 190 charlcd_gotoxy(lcd); 191 } 192 } 193 194 static void charlcd_clear_fast(struct charlcd *lcd) 195 { 196 struct hd44780_common *hdc = lcd->drvdata; 197 int pos; 198 199 charlcd_home(lcd); 200 201 if (lcd->ops->clear_fast) 202 lcd->ops->clear_fast(lcd); 203 else 204 for (pos = 0; pos < min(2, lcd->height) * hdc->hwidth; pos++) 205 hdc->write_data(hdc, ' '); 206 207 charlcd_home(lcd); 208 } 209 210 /* clears the display and resets X/Y */ 211 static void charlcd_clear_display(struct charlcd *lcd) 212 { 213 struct charlcd_priv *priv = charlcd_to_priv(lcd); 214 struct hd44780_common *hdc = lcd->drvdata; 215 216 hdc->write_cmd(hdc, 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 hd44780_common *hdc, int cmd); 226 struct charlcd_priv *priv = charlcd_to_priv(lcd); 227 struct hd44780_common *hdc = lcd->drvdata; 228 u8 init; 229 230 if (hdc->ifwidth != 4 && hdc->ifwidth != 8) 231 return -EINVAL; 232 233 priv->flags = ((lcd->height > 1) ? LCD_FLAG_N : 0) | LCD_FLAG_D | 234 LCD_FLAG_C | LCD_FLAG_B; 235 236 long_sleep(20); /* wait 20 ms after power-up for the paranoid */ 237 238 /* 239 * 8-bit mode, 1 line, small fonts; let's do it 3 times, to make sure 240 * the LCD is in 8-bit mode afterwards 241 */ 242 init = LCD_CMD_FUNCTION_SET | LCD_CMD_DATA_LEN_8BITS; 243 if (hdc->ifwidth == 4) { 244 init >>= 4; 245 write_cmd_raw = hdc->write_cmd_raw4; 246 } else { 247 write_cmd_raw = hdc->write_cmd; 248 } 249 write_cmd_raw(hdc, init); 250 long_sleep(10); 251 write_cmd_raw(hdc, init); 252 long_sleep(10); 253 write_cmd_raw(hdc, init); 254 long_sleep(10); 255 256 if (hdc->ifwidth == 4) { 257 /* Switch to 4-bit mode, 1 line, small fonts */ 258 hdc->write_cmd_raw4(hdc, LCD_CMD_FUNCTION_SET >> 4); 259 long_sleep(10); 260 } 261 262 /* set font height and lines number */ 263 hdc->write_cmd(hdc, 264 LCD_CMD_FUNCTION_SET | 265 ((hdc->ifwidth == 8) ? LCD_CMD_DATA_LEN_8BITS : 0) | 266 ((priv->flags & LCD_FLAG_F) ? LCD_CMD_FONT_5X10_DOTS : 0) | 267 ((priv->flags & LCD_FLAG_N) ? LCD_CMD_TWO_LINES : 0)); 268 long_sleep(10); 269 270 /* display off, cursor off, blink off */ 271 hdc->write_cmd(hdc, LCD_CMD_DISPLAY_CTRL); 272 long_sleep(10); 273 274 hdc->write_cmd(hdc, 275 LCD_CMD_DISPLAY_CTRL | /* set display mode */ 276 ((priv->flags & LCD_FLAG_D) ? LCD_CMD_DISPLAY_ON : 0) | 277 ((priv->flags & LCD_FLAG_C) ? LCD_CMD_CURSOR_ON : 0) | 278 ((priv->flags & LCD_FLAG_B) ? LCD_CMD_BLINK_ON : 0)); 279 280 charlcd_backlight(lcd, (priv->flags & LCD_FLAG_L) ? 1 : 0); 281 282 long_sleep(10); 283 284 /* entry mode set : increment, cursor shifting */ 285 hdc->write_cmd(hdc, LCD_CMD_ENTRY_MODE | LCD_CMD_CURSOR_INC); 286 287 charlcd_clear_display(lcd); 288 return 0; 289 } 290 291 /* 292 * Parses a movement command of the form "(.*);", where the group can be 293 * any number of subcommands of the form "(x|y)[0-9]+". 294 * 295 * Returns whether the command is valid. The position arguments are 296 * only written if the parsing was successful. 297 * 298 * For instance: 299 * - ";" returns (<original x>, <original y>). 300 * - "x1;" returns (1, <original y>). 301 * - "y2x1;" returns (1, 2). 302 * - "x12y34x56;" returns (56, 34). 303 * - "" fails. 304 * - "x" fails. 305 * - "x;" fails. 306 * - "x1" fails. 307 * - "xy12;" fails. 308 * - "x12yy12;" fails. 309 * - "xx" fails. 310 */ 311 static bool parse_xy(const char *s, unsigned long *x, unsigned long *y) 312 { 313 unsigned long new_x = *x; 314 unsigned long new_y = *y; 315 char *p; 316 317 for (;;) { 318 if (!*s) 319 return false; 320 321 if (*s == ';') 322 break; 323 324 if (*s == 'x') { 325 new_x = simple_strtoul(s + 1, &p, 10); 326 if (p == s + 1) 327 return false; 328 s = p; 329 } else if (*s == 'y') { 330 new_y = simple_strtoul(s + 1, &p, 10); 331 if (p == s + 1) 332 return false; 333 s = p; 334 } else { 335 return false; 336 } 337 } 338 339 *x = new_x; 340 *y = new_y; 341 return true; 342 } 343 344 /* 345 * These are the file operation function for user access to /dev/lcd 346 * This function can also be called from inside the kernel, by 347 * setting file and ppos to NULL. 348 * 349 */ 350 351 static inline int handle_lcd_special_code(struct charlcd *lcd) 352 { 353 struct charlcd_priv *priv = charlcd_to_priv(lcd); 354 struct hd44780_common *hdc = lcd->drvdata; 355 356 /* LCD special codes */ 357 358 int processed = 0; 359 360 char *esc = priv->esc_seq.buf + 2; 361 int oldflags = priv->flags; 362 363 /* check for display mode flags */ 364 switch (*esc) { 365 case 'D': /* Display ON */ 366 priv->flags |= LCD_FLAG_D; 367 processed = 1; 368 break; 369 case 'd': /* Display OFF */ 370 priv->flags &= ~LCD_FLAG_D; 371 processed = 1; 372 break; 373 case 'C': /* Cursor ON */ 374 priv->flags |= LCD_FLAG_C; 375 processed = 1; 376 break; 377 case 'c': /* Cursor OFF */ 378 priv->flags &= ~LCD_FLAG_C; 379 processed = 1; 380 break; 381 case 'B': /* Blink ON */ 382 priv->flags |= LCD_FLAG_B; 383 processed = 1; 384 break; 385 case 'b': /* Blink OFF */ 386 priv->flags &= ~LCD_FLAG_B; 387 processed = 1; 388 break; 389 case '+': /* Back light ON */ 390 priv->flags |= LCD_FLAG_L; 391 processed = 1; 392 break; 393 case '-': /* Back light OFF */ 394 priv->flags &= ~LCD_FLAG_L; 395 processed = 1; 396 break; 397 case '*': /* Flash back light */ 398 charlcd_poke(lcd); 399 processed = 1; 400 break; 401 case 'f': /* Small Font */ 402 priv->flags &= ~LCD_FLAG_F; 403 processed = 1; 404 break; 405 case 'F': /* Large Font */ 406 priv->flags |= LCD_FLAG_F; 407 processed = 1; 408 break; 409 case 'n': /* One Line */ 410 priv->flags &= ~LCD_FLAG_N; 411 processed = 1; 412 break; 413 case 'N': /* Two Lines */ 414 priv->flags |= LCD_FLAG_N; 415 processed = 1; 416 break; 417 case 'l': /* Shift Cursor Left */ 418 if (priv->addr.x > 0) { 419 /* back one char if not at end of line */ 420 if (priv->addr.x < hdc->bwidth) 421 hdc->write_cmd(hdc, LCD_CMD_SHIFT); 422 priv->addr.x--; 423 } 424 processed = 1; 425 break; 426 case 'r': /* shift cursor right */ 427 if (priv->addr.x < lcd->width) { 428 /* allow the cursor to pass the end of the line */ 429 if (priv->addr.x < (hdc->bwidth - 1)) 430 hdc->write_cmd(hdc, 431 LCD_CMD_SHIFT | LCD_CMD_SHIFT_RIGHT); 432 priv->addr.x++; 433 } 434 processed = 1; 435 break; 436 case 'L': /* shift display left */ 437 hdc->write_cmd(hdc, LCD_CMD_SHIFT | LCD_CMD_DISPLAY_SHIFT); 438 processed = 1; 439 break; 440 case 'R': /* shift display right */ 441 hdc->write_cmd(hdc, 442 LCD_CMD_SHIFT | LCD_CMD_DISPLAY_SHIFT | 443 LCD_CMD_SHIFT_RIGHT); 444 processed = 1; 445 break; 446 case 'k': { /* kill end of line */ 447 int x; 448 449 for (x = priv->addr.x; x < hdc->bwidth; x++) 450 hdc->write_data(hdc, ' '); 451 452 /* restore cursor position */ 453 charlcd_gotoxy(lcd); 454 processed = 1; 455 break; 456 } 457 case 'I': /* reinitialize display */ 458 charlcd_init_display(lcd); 459 processed = 1; 460 break; 461 case 'G': { 462 /* Generator : LGcxxxxx...xx; must have <c> between '0' 463 * and '7', representing the numerical ASCII code of the 464 * redefined character, and <xx...xx> a sequence of 16 465 * hex digits representing 8 bytes for each character. 466 * Most LCDs will only use 5 lower bits of the 7 first 467 * bytes. 468 */ 469 470 unsigned char cgbytes[8]; 471 unsigned char cgaddr; 472 int cgoffset; 473 int shift; 474 char value; 475 int addr; 476 477 if (!strchr(esc, ';')) 478 break; 479 480 esc++; 481 482 cgaddr = *(esc++) - '0'; 483 if (cgaddr > 7) { 484 processed = 1; 485 break; 486 } 487 488 cgoffset = 0; 489 shift = 0; 490 value = 0; 491 while (*esc && cgoffset < 8) { 492 int half; 493 494 shift ^= 4; 495 496 half = hex_to_bin(*esc++); 497 if (half < 0) 498 continue; 499 500 value |= half << shift; 501 if (shift == 0) { 502 cgbytes[cgoffset++] = value; 503 value = 0; 504 } 505 } 506 507 hdc->write_cmd(hdc, LCD_CMD_SET_CGRAM_ADDR | (cgaddr * 8)); 508 for (addr = 0; addr < cgoffset; addr++) 509 hdc->write_data(hdc, cgbytes[addr]); 510 511 /* ensures that we stop writing to CGRAM */ 512 charlcd_gotoxy(lcd); 513 processed = 1; 514 break; 515 } 516 case 'x': /* gotoxy : LxXXX[yYYY]; */ 517 case 'y': /* gotoxy : LyYYY[xXXX]; */ 518 if (priv->esc_seq.buf[priv->esc_seq.len - 1] != ';') 519 break; 520 521 /* If the command is valid, move to the new address */ 522 if (parse_xy(esc, &priv->addr.x, &priv->addr.y)) 523 charlcd_gotoxy(lcd); 524 525 /* Regardless of its validity, mark as processed */ 526 processed = 1; 527 break; 528 } 529 530 /* TODO: This indent party here got ugly, clean it! */ 531 /* Check whether one flag was changed */ 532 if (oldflags == priv->flags) 533 return processed; 534 535 /* check whether one of B,C,D flags were changed */ 536 if ((oldflags ^ priv->flags) & 537 (LCD_FLAG_B | LCD_FLAG_C | LCD_FLAG_D)) 538 /* set display mode */ 539 hdc->write_cmd(hdc, 540 LCD_CMD_DISPLAY_CTRL | 541 ((priv->flags & LCD_FLAG_D) ? LCD_CMD_DISPLAY_ON : 0) | 542 ((priv->flags & LCD_FLAG_C) ? LCD_CMD_CURSOR_ON : 0) | 543 ((priv->flags & LCD_FLAG_B) ? LCD_CMD_BLINK_ON : 0)); 544 /* check whether one of F,N flags was changed */ 545 else if ((oldflags ^ priv->flags) & (LCD_FLAG_F | LCD_FLAG_N)) 546 hdc->write_cmd(hdc, 547 LCD_CMD_FUNCTION_SET | 548 ((hdc->ifwidth == 8) ? LCD_CMD_DATA_LEN_8BITS : 0) | 549 ((priv->flags & LCD_FLAG_F) ? LCD_CMD_FONT_5X10_DOTS : 0) | 550 ((priv->flags & LCD_FLAG_N) ? LCD_CMD_TWO_LINES : 0)); 551 /* check whether L flag was changed */ 552 else if ((oldflags ^ priv->flags) & LCD_FLAG_L) 553 charlcd_backlight(lcd, !!(priv->flags & LCD_FLAG_L)); 554 555 return processed; 556 } 557 558 static void charlcd_write_char(struct charlcd *lcd, char c) 559 { 560 struct charlcd_priv *priv = charlcd_to_priv(lcd); 561 struct hd44780_common *hdc = lcd->drvdata; 562 563 /* first, we'll test if we're in escape mode */ 564 if ((c != '\n') && priv->esc_seq.len >= 0) { 565 /* yes, let's add this char to the buffer */ 566 priv->esc_seq.buf[priv->esc_seq.len++] = c; 567 priv->esc_seq.buf[priv->esc_seq.len] = '\0'; 568 } else { 569 /* aborts any previous escape sequence */ 570 priv->esc_seq.len = -1; 571 572 switch (c) { 573 case LCD_ESCAPE_CHAR: 574 /* start of an escape sequence */ 575 priv->esc_seq.len = 0; 576 priv->esc_seq.buf[priv->esc_seq.len] = '\0'; 577 break; 578 case '\b': 579 /* go back one char and clear it */ 580 if (priv->addr.x > 0) { 581 /* 582 * check if we're not at the 583 * end of the line 584 */ 585 if (priv->addr.x < hdc->bwidth) 586 /* back one char */ 587 hdc->write_cmd(hdc, LCD_CMD_SHIFT); 588 priv->addr.x--; 589 } 590 /* replace with a space */ 591 hdc->write_data(hdc, ' '); 592 /* back one char again */ 593 hdc->write_cmd(hdc, LCD_CMD_SHIFT); 594 break; 595 case '\f': 596 /* quickly clear the display */ 597 charlcd_clear_fast(lcd); 598 break; 599 case '\n': 600 /* 601 * flush the remainder of the current line and 602 * go to the beginning of the next line 603 */ 604 for (; priv->addr.x < hdc->bwidth; priv->addr.x++) 605 hdc->write_data(hdc, ' '); 606 priv->addr.x = 0; 607 priv->addr.y = (priv->addr.y + 1) % lcd->height; 608 charlcd_gotoxy(lcd); 609 break; 610 case '\r': 611 /* go to the beginning of the same line */ 612 priv->addr.x = 0; 613 charlcd_gotoxy(lcd); 614 break; 615 case '\t': 616 /* print a space instead of the tab */ 617 charlcd_print(lcd, ' '); 618 break; 619 default: 620 /* simply print this char */ 621 charlcd_print(lcd, c); 622 break; 623 } 624 } 625 626 /* 627 * now we'll see if we're in an escape mode and if the current 628 * escape sequence can be understood. 629 */ 630 if (priv->esc_seq.len >= 2) { 631 int processed = 0; 632 633 if (!strcmp(priv->esc_seq.buf, "[2J")) { 634 /* clear the display */ 635 charlcd_clear_fast(lcd); 636 processed = 1; 637 } else if (!strcmp(priv->esc_seq.buf, "[H")) { 638 /* cursor to home */ 639 charlcd_home(lcd); 640 processed = 1; 641 } 642 /* codes starting with ^[[L */ 643 else if ((priv->esc_seq.len >= 3) && 644 (priv->esc_seq.buf[0] == '[') && 645 (priv->esc_seq.buf[1] == 'L')) { 646 processed = handle_lcd_special_code(lcd); 647 } 648 649 /* LCD special escape codes */ 650 /* 651 * flush the escape sequence if it's been processed 652 * or if it is getting too long. 653 */ 654 if (processed || (priv->esc_seq.len >= LCD_ESCAPE_LEN)) 655 priv->esc_seq.len = -1; 656 } /* escape codes */ 657 } 658 659 static struct charlcd *the_charlcd; 660 661 static ssize_t charlcd_write(struct file *file, const char __user *buf, 662 size_t count, loff_t *ppos) 663 { 664 const char __user *tmp = buf; 665 char c; 666 667 for (; count-- > 0; (*ppos)++, tmp++) { 668 if (!in_interrupt() && (((count + 1) & 0x1f) == 0)) 669 /* 670 * let's be a little nice with other processes 671 * that need some CPU 672 */ 673 schedule(); 674 675 if (get_user(c, tmp)) 676 return -EFAULT; 677 678 charlcd_write_char(the_charlcd, c); 679 } 680 681 return tmp - buf; 682 } 683 684 static int charlcd_open(struct inode *inode, struct file *file) 685 { 686 struct charlcd_priv *priv = charlcd_to_priv(the_charlcd); 687 int ret; 688 689 ret = -EBUSY; 690 if (!atomic_dec_and_test(&charlcd_available)) 691 goto fail; /* open only once at a time */ 692 693 ret = -EPERM; 694 if (file->f_mode & FMODE_READ) /* device is write-only */ 695 goto fail; 696 697 if (priv->must_clear) { 698 charlcd_clear_display(&priv->lcd); 699 priv->must_clear = false; 700 } 701 return nonseekable_open(inode, file); 702 703 fail: 704 atomic_inc(&charlcd_available); 705 return ret; 706 } 707 708 static int charlcd_release(struct inode *inode, struct file *file) 709 { 710 atomic_inc(&charlcd_available); 711 return 0; 712 } 713 714 static const struct file_operations charlcd_fops = { 715 .write = charlcd_write, 716 .open = charlcd_open, 717 .release = charlcd_release, 718 .llseek = no_llseek, 719 }; 720 721 static struct miscdevice charlcd_dev = { 722 .minor = LCD_MINOR, 723 .name = "lcd", 724 .fops = &charlcd_fops, 725 }; 726 727 static void charlcd_puts(struct charlcd *lcd, const char *s) 728 { 729 const char *tmp = s; 730 int count = strlen(s); 731 732 for (; count-- > 0; tmp++) { 733 if (!in_interrupt() && (((count + 1) & 0x1f) == 0)) 734 /* 735 * let's be a little nice with other processes 736 * that need some CPU 737 */ 738 schedule(); 739 740 charlcd_write_char(lcd, *tmp); 741 } 742 } 743 744 #ifdef CONFIG_PANEL_BOOT_MESSAGE 745 #define LCD_INIT_TEXT CONFIG_PANEL_BOOT_MESSAGE 746 #else 747 #define LCD_INIT_TEXT "Linux-" UTS_RELEASE "\n" 748 #endif 749 750 #ifdef CONFIG_CHARLCD_BL_ON 751 #define LCD_INIT_BL "\x1b[L+" 752 #elif defined(CONFIG_CHARLCD_BL_FLASH) 753 #define LCD_INIT_BL "\x1b[L*" 754 #else 755 #define LCD_INIT_BL "\x1b[L-" 756 #endif 757 758 /* initialize the LCD driver */ 759 static int charlcd_init(struct charlcd *lcd) 760 { 761 struct charlcd_priv *priv = charlcd_to_priv(lcd); 762 int ret; 763 764 if (lcd->ops->backlight) { 765 mutex_init(&priv->bl_tempo_lock); 766 INIT_DELAYED_WORK(&priv->bl_work, charlcd_bl_off); 767 } 768 769 /* 770 * before this line, we must NOT send anything to the display. 771 * Since charlcd_init_display() needs to write data, we have to 772 * enable mark the LCD initialized just before. 773 */ 774 ret = charlcd_init_display(lcd); 775 if (ret) 776 return ret; 777 778 /* display a short message */ 779 charlcd_puts(lcd, "\x1b[Lc\x1b[Lb" LCD_INIT_BL LCD_INIT_TEXT); 780 781 /* clear the display on the next device opening */ 782 priv->must_clear = true; 783 charlcd_home(lcd); 784 return 0; 785 } 786 787 struct charlcd *charlcd_alloc(void) 788 { 789 struct charlcd_priv *priv; 790 struct charlcd *lcd; 791 792 priv = kzalloc(sizeof(*priv), GFP_KERNEL); 793 if (!priv) 794 return NULL; 795 796 priv->esc_seq.len = -1; 797 798 lcd = &priv->lcd; 799 800 return lcd; 801 } 802 EXPORT_SYMBOL_GPL(charlcd_alloc); 803 804 void charlcd_free(struct charlcd *lcd) 805 { 806 kfree(charlcd_to_priv(lcd)); 807 } 808 EXPORT_SYMBOL_GPL(charlcd_free); 809 810 static int panel_notify_sys(struct notifier_block *this, unsigned long code, 811 void *unused) 812 { 813 struct charlcd *lcd = the_charlcd; 814 815 switch (code) { 816 case SYS_DOWN: 817 charlcd_puts(lcd, 818 "\x0cReloading\nSystem...\x1b[Lc\x1b[Lb\x1b[L+"); 819 break; 820 case SYS_HALT: 821 charlcd_puts(lcd, "\x0cSystem Halted.\x1b[Lc\x1b[Lb\x1b[L+"); 822 break; 823 case SYS_POWER_OFF: 824 charlcd_puts(lcd, "\x0cPower off.\x1b[Lc\x1b[Lb\x1b[L+"); 825 break; 826 default: 827 break; 828 } 829 return NOTIFY_DONE; 830 } 831 832 static struct notifier_block panel_notifier = { 833 panel_notify_sys, 834 NULL, 835 0 836 }; 837 838 int charlcd_register(struct charlcd *lcd) 839 { 840 int ret; 841 842 ret = charlcd_init(lcd); 843 if (ret) 844 return ret; 845 846 ret = misc_register(&charlcd_dev); 847 if (ret) 848 return ret; 849 850 the_charlcd = lcd; 851 register_reboot_notifier(&panel_notifier); 852 return 0; 853 } 854 EXPORT_SYMBOL_GPL(charlcd_register); 855 856 int charlcd_unregister(struct charlcd *lcd) 857 { 858 struct charlcd_priv *priv = charlcd_to_priv(lcd); 859 860 unregister_reboot_notifier(&panel_notifier); 861 charlcd_puts(lcd, "\x0cLCD driver unloaded.\x1b[Lc\x1b[Lb\x1b[L-"); 862 misc_deregister(&charlcd_dev); 863 the_charlcd = NULL; 864 if (lcd->ops->backlight) { 865 cancel_delayed_work_sync(&priv->bl_work); 866 priv->lcd.ops->backlight(&priv->lcd, 0); 867 } 868 869 return 0; 870 } 871 EXPORT_SYMBOL_GPL(charlcd_unregister); 872 873 MODULE_LICENSE("GPL"); 874