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 lcd->ops->write_cmd(lcd, 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 lcd->ops->write_data(lcd, c); 186 priv->addr.x++; 187 188 /* prevents the cursor from wrapping onto the next line */ 189 if (priv->addr.x == 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 lcd->ops->write_data(lcd, ' '); 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); 214 215 lcd->ops->write_cmd(lcd, LCD_CMD_DISPLAY_CLEAR); 216 priv->addr.x = 0; 217 priv->addr.y = 0; 218 /* we must wait a few milliseconds (15) */ 219 long_sleep(15); 220 } 221 222 static int charlcd_init_display(struct charlcd *lcd) 223 { 224 void (*write_cmd_raw)(struct charlcd *lcd, int cmd); 225 struct charlcd_priv *priv = charlcd_to_priv(lcd); 226 struct hd44780_common *hdc = lcd->drvdata; 227 u8 init; 228 229 if (hdc->ifwidth != 4 && hdc->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 (hdc->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 (hdc->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 ((hdc->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 struct hd44780_common *hdc = lcd->drvdata; 354 355 /* LCD special codes */ 356 357 int processed = 0; 358 359 char *esc = priv->esc_seq.buf + 2; 360 int oldflags = priv->flags; 361 362 /* check for display mode flags */ 363 switch (*esc) { 364 case 'D': /* Display ON */ 365 priv->flags |= LCD_FLAG_D; 366 processed = 1; 367 break; 368 case 'd': /* Display OFF */ 369 priv->flags &= ~LCD_FLAG_D; 370 processed = 1; 371 break; 372 case 'C': /* Cursor ON */ 373 priv->flags |= LCD_FLAG_C; 374 processed = 1; 375 break; 376 case 'c': /* Cursor OFF */ 377 priv->flags &= ~LCD_FLAG_C; 378 processed = 1; 379 break; 380 case 'B': /* Blink ON */ 381 priv->flags |= LCD_FLAG_B; 382 processed = 1; 383 break; 384 case 'b': /* Blink OFF */ 385 priv->flags &= ~LCD_FLAG_B; 386 processed = 1; 387 break; 388 case '+': /* Back light ON */ 389 priv->flags |= LCD_FLAG_L; 390 processed = 1; 391 break; 392 case '-': /* Back light OFF */ 393 priv->flags &= ~LCD_FLAG_L; 394 processed = 1; 395 break; 396 case '*': /* Flash back light */ 397 charlcd_poke(lcd); 398 processed = 1; 399 break; 400 case 'f': /* Small Font */ 401 priv->flags &= ~LCD_FLAG_F; 402 processed = 1; 403 break; 404 case 'F': /* Large Font */ 405 priv->flags |= LCD_FLAG_F; 406 processed = 1; 407 break; 408 case 'n': /* One Line */ 409 priv->flags &= ~LCD_FLAG_N; 410 processed = 1; 411 break; 412 case 'N': /* Two Lines */ 413 priv->flags |= LCD_FLAG_N; 414 processed = 1; 415 break; 416 case 'l': /* Shift Cursor Left */ 417 if (priv->addr.x > 0) { 418 /* back one char if not at end of line */ 419 if (priv->addr.x < hdc->bwidth) 420 lcd->ops->write_cmd(lcd, LCD_CMD_SHIFT); 421 priv->addr.x--; 422 } 423 processed = 1; 424 break; 425 case 'r': /* shift cursor right */ 426 if (priv->addr.x < lcd->width) { 427 /* allow the cursor to pass the end of the line */ 428 if (priv->addr.x < (hdc->bwidth - 1)) 429 lcd->ops->write_cmd(lcd, 430 LCD_CMD_SHIFT | LCD_CMD_SHIFT_RIGHT); 431 priv->addr.x++; 432 } 433 processed = 1; 434 break; 435 case 'L': /* shift display left */ 436 lcd->ops->write_cmd(lcd, LCD_CMD_SHIFT | LCD_CMD_DISPLAY_SHIFT); 437 processed = 1; 438 break; 439 case 'R': /* shift display right */ 440 lcd->ops->write_cmd(lcd, 441 LCD_CMD_SHIFT | LCD_CMD_DISPLAY_SHIFT | 442 LCD_CMD_SHIFT_RIGHT); 443 processed = 1; 444 break; 445 case 'k': { /* kill end of line */ 446 int x; 447 448 for (x = priv->addr.x; x < hdc->bwidth; x++) 449 lcd->ops->write_data(lcd, ' '); 450 451 /* restore cursor position */ 452 charlcd_gotoxy(lcd); 453 processed = 1; 454 break; 455 } 456 case 'I': /* reinitialize display */ 457 charlcd_init_display(lcd); 458 processed = 1; 459 break; 460 case 'G': { 461 /* Generator : LGcxxxxx...xx; must have <c> between '0' 462 * and '7', representing the numerical ASCII code of the 463 * redefined character, and <xx...xx> a sequence of 16 464 * hex digits representing 8 bytes for each character. 465 * Most LCDs will only use 5 lower bits of the 7 first 466 * bytes. 467 */ 468 469 unsigned char cgbytes[8]; 470 unsigned char cgaddr; 471 int cgoffset; 472 int shift; 473 char value; 474 int addr; 475 476 if (!strchr(esc, ';')) 477 break; 478 479 esc++; 480 481 cgaddr = *(esc++) - '0'; 482 if (cgaddr > 7) { 483 processed = 1; 484 break; 485 } 486 487 cgoffset = 0; 488 shift = 0; 489 value = 0; 490 while (*esc && cgoffset < 8) { 491 int half; 492 493 shift ^= 4; 494 495 half = hex_to_bin(*esc++); 496 if (half < 0) 497 continue; 498 499 value |= half << shift; 500 if (shift == 0) { 501 cgbytes[cgoffset++] = value; 502 value = 0; 503 } 504 } 505 506 lcd->ops->write_cmd(lcd, LCD_CMD_SET_CGRAM_ADDR | (cgaddr * 8)); 507 for (addr = 0; addr < cgoffset; addr++) 508 lcd->ops->write_data(lcd, cgbytes[addr]); 509 510 /* ensures that we stop writing to CGRAM */ 511 charlcd_gotoxy(lcd); 512 processed = 1; 513 break; 514 } 515 case 'x': /* gotoxy : LxXXX[yYYY]; */ 516 case 'y': /* gotoxy : LyYYY[xXXX]; */ 517 if (priv->esc_seq.buf[priv->esc_seq.len - 1] != ';') 518 break; 519 520 /* If the command is valid, move to the new address */ 521 if (parse_xy(esc, &priv->addr.x, &priv->addr.y)) 522 charlcd_gotoxy(lcd); 523 524 /* Regardless of its validity, mark as processed */ 525 processed = 1; 526 break; 527 } 528 529 /* TODO: This indent party here got ugly, clean it! */ 530 /* Check whether one flag was changed */ 531 if (oldflags == priv->flags) 532 return processed; 533 534 /* check whether one of B,C,D flags were changed */ 535 if ((oldflags ^ priv->flags) & 536 (LCD_FLAG_B | LCD_FLAG_C | LCD_FLAG_D)) 537 /* set display mode */ 538 lcd->ops->write_cmd(lcd, 539 LCD_CMD_DISPLAY_CTRL | 540 ((priv->flags & LCD_FLAG_D) ? LCD_CMD_DISPLAY_ON : 0) | 541 ((priv->flags & LCD_FLAG_C) ? LCD_CMD_CURSOR_ON : 0) | 542 ((priv->flags & LCD_FLAG_B) ? LCD_CMD_BLINK_ON : 0)); 543 /* check whether one of F,N flags was changed */ 544 else if ((oldflags ^ priv->flags) & (LCD_FLAG_F | LCD_FLAG_N)) 545 lcd->ops->write_cmd(lcd, 546 LCD_CMD_FUNCTION_SET | 547 ((hdc->ifwidth == 8) ? LCD_CMD_DATA_LEN_8BITS : 0) | 548 ((priv->flags & LCD_FLAG_F) ? LCD_CMD_FONT_5X10_DOTS : 0) | 549 ((priv->flags & LCD_FLAG_N) ? LCD_CMD_TWO_LINES : 0)); 550 /* check whether L flag was changed */ 551 else if ((oldflags ^ priv->flags) & LCD_FLAG_L) 552 charlcd_backlight(lcd, !!(priv->flags & LCD_FLAG_L)); 553 554 return processed; 555 } 556 557 static void charlcd_write_char(struct charlcd *lcd, char c) 558 { 559 struct charlcd_priv *priv = charlcd_to_priv(lcd); 560 struct hd44780_common *hdc = lcd->drvdata; 561 562 /* first, we'll test if we're in escape mode */ 563 if ((c != '\n') && priv->esc_seq.len >= 0) { 564 /* yes, let's add this char to the buffer */ 565 priv->esc_seq.buf[priv->esc_seq.len++] = c; 566 priv->esc_seq.buf[priv->esc_seq.len] = '\0'; 567 } else { 568 /* aborts any previous escape sequence */ 569 priv->esc_seq.len = -1; 570 571 switch (c) { 572 case LCD_ESCAPE_CHAR: 573 /* start of an escape sequence */ 574 priv->esc_seq.len = 0; 575 priv->esc_seq.buf[priv->esc_seq.len] = '\0'; 576 break; 577 case '\b': 578 /* go back one char and clear it */ 579 if (priv->addr.x > 0) { 580 /* 581 * check if we're not at the 582 * end of the line 583 */ 584 if (priv->addr.x < hdc->bwidth) 585 /* back one char */ 586 lcd->ops->write_cmd(lcd, LCD_CMD_SHIFT); 587 priv->addr.x--; 588 } 589 /* replace with a space */ 590 lcd->ops->write_data(lcd, ' '); 591 /* back one char again */ 592 lcd->ops->write_cmd(lcd, LCD_CMD_SHIFT); 593 break; 594 case '\f': 595 /* quickly clear the display */ 596 charlcd_clear_fast(lcd); 597 break; 598 case '\n': 599 /* 600 * flush the remainder of the current line and 601 * go to the beginning of the next line 602 */ 603 for (; priv->addr.x < hdc->bwidth; priv->addr.x++) 604 lcd->ops->write_data(lcd, ' '); 605 priv->addr.x = 0; 606 priv->addr.y = (priv->addr.y + 1) % lcd->height; 607 charlcd_gotoxy(lcd); 608 break; 609 case '\r': 610 /* go to the beginning of the same line */ 611 priv->addr.x = 0; 612 charlcd_gotoxy(lcd); 613 break; 614 case '\t': 615 /* print a space instead of the tab */ 616 charlcd_print(lcd, ' '); 617 break; 618 default: 619 /* simply print this char */ 620 charlcd_print(lcd, c); 621 break; 622 } 623 } 624 625 /* 626 * now we'll see if we're in an escape mode and if the current 627 * escape sequence can be understood. 628 */ 629 if (priv->esc_seq.len >= 2) { 630 int processed = 0; 631 632 if (!strcmp(priv->esc_seq.buf, "[2J")) { 633 /* clear the display */ 634 charlcd_clear_fast(lcd); 635 processed = 1; 636 } else if (!strcmp(priv->esc_seq.buf, "[H")) { 637 /* cursor to home */ 638 charlcd_home(lcd); 639 processed = 1; 640 } 641 /* codes starting with ^[[L */ 642 else if ((priv->esc_seq.len >= 3) && 643 (priv->esc_seq.buf[0] == '[') && 644 (priv->esc_seq.buf[1] == 'L')) { 645 processed = handle_lcd_special_code(lcd); 646 } 647 648 /* LCD special escape codes */ 649 /* 650 * flush the escape sequence if it's been processed 651 * or if it is getting too long. 652 */ 653 if (processed || (priv->esc_seq.len >= LCD_ESCAPE_LEN)) 654 priv->esc_seq.len = -1; 655 } /* escape codes */ 656 } 657 658 static struct charlcd *the_charlcd; 659 660 static ssize_t charlcd_write(struct file *file, const char __user *buf, 661 size_t count, loff_t *ppos) 662 { 663 const char __user *tmp = buf; 664 char c; 665 666 for (; count-- > 0; (*ppos)++, tmp++) { 667 if (!in_interrupt() && (((count + 1) & 0x1f) == 0)) 668 /* 669 * let's be a little nice with other processes 670 * that need some CPU 671 */ 672 schedule(); 673 674 if (get_user(c, tmp)) 675 return -EFAULT; 676 677 charlcd_write_char(the_charlcd, c); 678 } 679 680 return tmp - buf; 681 } 682 683 static int charlcd_open(struct inode *inode, struct file *file) 684 { 685 struct charlcd_priv *priv = charlcd_to_priv(the_charlcd); 686 int ret; 687 688 ret = -EBUSY; 689 if (!atomic_dec_and_test(&charlcd_available)) 690 goto fail; /* open only once at a time */ 691 692 ret = -EPERM; 693 if (file->f_mode & FMODE_READ) /* device is write-only */ 694 goto fail; 695 696 if (priv->must_clear) { 697 charlcd_clear_display(&priv->lcd); 698 priv->must_clear = false; 699 } 700 return nonseekable_open(inode, file); 701 702 fail: 703 atomic_inc(&charlcd_available); 704 return ret; 705 } 706 707 static int charlcd_release(struct inode *inode, struct file *file) 708 { 709 atomic_inc(&charlcd_available); 710 return 0; 711 } 712 713 static const struct file_operations charlcd_fops = { 714 .write = charlcd_write, 715 .open = charlcd_open, 716 .release = charlcd_release, 717 .llseek = no_llseek, 718 }; 719 720 static struct miscdevice charlcd_dev = { 721 .minor = LCD_MINOR, 722 .name = "lcd", 723 .fops = &charlcd_fops, 724 }; 725 726 static void charlcd_puts(struct charlcd *lcd, const char *s) 727 { 728 const char *tmp = s; 729 int count = strlen(s); 730 731 for (; count-- > 0; tmp++) { 732 if (!in_interrupt() && (((count + 1) & 0x1f) == 0)) 733 /* 734 * let's be a little nice with other processes 735 * that need some CPU 736 */ 737 schedule(); 738 739 charlcd_write_char(lcd, *tmp); 740 } 741 } 742 743 #ifdef CONFIG_PANEL_BOOT_MESSAGE 744 #define LCD_INIT_TEXT CONFIG_PANEL_BOOT_MESSAGE 745 #else 746 #define LCD_INIT_TEXT "Linux-" UTS_RELEASE "\n" 747 #endif 748 749 #ifdef CONFIG_CHARLCD_BL_ON 750 #define LCD_INIT_BL "\x1b[L+" 751 #elif defined(CONFIG_CHARLCD_BL_FLASH) 752 #define LCD_INIT_BL "\x1b[L*" 753 #else 754 #define LCD_INIT_BL "\x1b[L-" 755 #endif 756 757 /* initialize the LCD driver */ 758 static int charlcd_init(struct charlcd *lcd) 759 { 760 struct charlcd_priv *priv = charlcd_to_priv(lcd); 761 int ret; 762 763 if (lcd->ops->backlight) { 764 mutex_init(&priv->bl_tempo_lock); 765 INIT_DELAYED_WORK(&priv->bl_work, charlcd_bl_off); 766 } 767 768 /* 769 * before this line, we must NOT send anything to the display. 770 * Since charlcd_init_display() needs to write data, we have to 771 * enable mark the LCD initialized just before. 772 */ 773 ret = charlcd_init_display(lcd); 774 if (ret) 775 return ret; 776 777 /* display a short message */ 778 charlcd_puts(lcd, "\x1b[Lc\x1b[Lb" LCD_INIT_BL LCD_INIT_TEXT); 779 780 /* clear the display on the next device opening */ 781 priv->must_clear = true; 782 charlcd_home(lcd); 783 return 0; 784 } 785 786 struct charlcd *charlcd_alloc(void) 787 { 788 struct charlcd_priv *priv; 789 struct charlcd *lcd; 790 791 priv = kzalloc(sizeof(*priv), GFP_KERNEL); 792 if (!priv) 793 return NULL; 794 795 priv->esc_seq.len = -1; 796 797 lcd = &priv->lcd; 798 799 return lcd; 800 } 801 EXPORT_SYMBOL_GPL(charlcd_alloc); 802 803 void charlcd_free(struct charlcd *lcd) 804 { 805 kfree(charlcd_to_priv(lcd)); 806 } 807 EXPORT_SYMBOL_GPL(charlcd_free); 808 809 static int panel_notify_sys(struct notifier_block *this, unsigned long code, 810 void *unused) 811 { 812 struct charlcd *lcd = the_charlcd; 813 814 switch (code) { 815 case SYS_DOWN: 816 charlcd_puts(lcd, 817 "\x0cReloading\nSystem...\x1b[Lc\x1b[Lb\x1b[L+"); 818 break; 819 case SYS_HALT: 820 charlcd_puts(lcd, "\x0cSystem Halted.\x1b[Lc\x1b[Lb\x1b[L+"); 821 break; 822 case SYS_POWER_OFF: 823 charlcd_puts(lcd, "\x0cPower off.\x1b[Lc\x1b[Lb\x1b[L+"); 824 break; 825 default: 826 break; 827 } 828 return NOTIFY_DONE; 829 } 830 831 static struct notifier_block panel_notifier = { 832 panel_notify_sys, 833 NULL, 834 0 835 }; 836 837 int charlcd_register(struct charlcd *lcd) 838 { 839 int ret; 840 841 ret = charlcd_init(lcd); 842 if (ret) 843 return ret; 844 845 ret = misc_register(&charlcd_dev); 846 if (ret) 847 return ret; 848 849 the_charlcd = lcd; 850 register_reboot_notifier(&panel_notifier); 851 return 0; 852 } 853 EXPORT_SYMBOL_GPL(charlcd_register); 854 855 int charlcd_unregister(struct charlcd *lcd) 856 { 857 struct charlcd_priv *priv = charlcd_to_priv(lcd); 858 859 unregister_reboot_notifier(&panel_notifier); 860 charlcd_puts(lcd, "\x0cLCD driver unloaded.\x1b[Lc\x1b[Lb\x1b[L-"); 861 misc_deregister(&charlcd_dev); 862 the_charlcd = NULL; 863 if (lcd->ops->backlight) { 864 cancel_delayed_work_sync(&priv->bl_work); 865 priv->lcd.ops->backlight(&priv->lcd, 0); 866 } 867 868 return 0; 869 } 870 EXPORT_SYMBOL_GPL(charlcd_unregister); 871 872 MODULE_LICENSE("GPL"); 873