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/fs.h> 12 #include <linux/miscdevice.h> 13 #include <linux/module.h> 14 #include <linux/notifier.h> 15 #include <linux/reboot.h> 16 #include <linux/slab.h> 17 #include <linux/uaccess.h> 18 #include <linux/workqueue.h> 19 20 #include <generated/utsrelease.h> 21 22 #include "charlcd.h" 23 24 /* Keep the backlight on this many seconds for each flash */ 25 #define LCD_BL_TEMPO_PERIOD 4 26 27 #define LCD_ESCAPE_LEN 24 /* Max chars for LCD escape command */ 28 #define LCD_ESCAPE_CHAR 27 /* Use char 27 for escape command */ 29 30 struct charlcd_priv { 31 struct charlcd lcd; 32 33 struct delayed_work bl_work; 34 struct mutex bl_tempo_lock; /* Protects access to bl_tempo */ 35 bool bl_tempo; 36 37 bool must_clear; 38 39 /* contains the LCD config state */ 40 unsigned long flags; 41 42 /* Current escape sequence and it's length or -1 if outside */ 43 struct { 44 char buf[LCD_ESCAPE_LEN + 1]; 45 int len; 46 } esc_seq; 47 48 unsigned long long drvdata[]; 49 }; 50 51 #define charlcd_to_priv(p) container_of(p, struct charlcd_priv, lcd) 52 53 /* Device single-open policy control */ 54 static atomic_t charlcd_available = ATOMIC_INIT(1); 55 56 /* turn the backlight on or off */ 57 void charlcd_backlight(struct charlcd *lcd, enum charlcd_onoff on) 58 { 59 struct charlcd_priv *priv = charlcd_to_priv(lcd); 60 61 if (!lcd->ops->backlight) 62 return; 63 64 mutex_lock(&priv->bl_tempo_lock); 65 if (!priv->bl_tempo) 66 lcd->ops->backlight(lcd, on); 67 mutex_unlock(&priv->bl_tempo_lock); 68 } 69 EXPORT_SYMBOL_GPL(charlcd_backlight); 70 71 static void charlcd_bl_off(struct work_struct *work) 72 { 73 struct delayed_work *dwork = to_delayed_work(work); 74 struct charlcd_priv *priv = 75 container_of(dwork, struct charlcd_priv, bl_work); 76 77 mutex_lock(&priv->bl_tempo_lock); 78 if (priv->bl_tempo) { 79 priv->bl_tempo = false; 80 if (!(priv->flags & LCD_FLAG_L)) 81 priv->lcd.ops->backlight(&priv->lcd, CHARLCD_OFF); 82 } 83 mutex_unlock(&priv->bl_tempo_lock); 84 } 85 86 /* turn the backlight on for a little while */ 87 void charlcd_poke(struct charlcd *lcd) 88 { 89 struct charlcd_priv *priv = charlcd_to_priv(lcd); 90 91 if (!lcd->ops->backlight) 92 return; 93 94 cancel_delayed_work_sync(&priv->bl_work); 95 96 mutex_lock(&priv->bl_tempo_lock); 97 if (!priv->bl_tempo && !(priv->flags & LCD_FLAG_L)) 98 lcd->ops->backlight(lcd, CHARLCD_ON); 99 priv->bl_tempo = true; 100 schedule_delayed_work(&priv->bl_work, LCD_BL_TEMPO_PERIOD * HZ); 101 mutex_unlock(&priv->bl_tempo_lock); 102 } 103 EXPORT_SYMBOL_GPL(charlcd_poke); 104 105 static void charlcd_home(struct charlcd *lcd) 106 { 107 lcd->addr.x = 0; 108 lcd->addr.y = 0; 109 lcd->ops->home(lcd); 110 } 111 112 static void charlcd_print(struct charlcd *lcd, char c) 113 { 114 if (lcd->addr.x >= lcd->width) 115 return; 116 117 if (lcd->char_conv) 118 c = lcd->char_conv[(unsigned char)c]; 119 120 if (!lcd->ops->print(lcd, c)) 121 lcd->addr.x++; 122 123 /* prevents the cursor from wrapping onto the next line */ 124 if (lcd->addr.x == lcd->width) 125 lcd->ops->gotoxy(lcd, lcd->addr.x - 1, lcd->addr.y); 126 } 127 128 static void charlcd_clear_display(struct charlcd *lcd) 129 { 130 lcd->ops->clear_display(lcd); 131 lcd->addr.x = 0; 132 lcd->addr.y = 0; 133 } 134 135 /* 136 * Parses a movement command of the form "(.*);", where the group can be 137 * any number of subcommands of the form "(x|y)[0-9]+". 138 * 139 * Returns whether the command is valid. The position arguments are 140 * only written if the parsing was successful. 141 * 142 * For instance: 143 * - ";" returns (<original x>, <original y>). 144 * - "x1;" returns (1, <original y>). 145 * - "y2x1;" returns (1, 2). 146 * - "x12y34x56;" returns (56, 34). 147 * - "" fails. 148 * - "x" fails. 149 * - "x;" fails. 150 * - "x1" fails. 151 * - "xy12;" fails. 152 * - "x12yy12;" fails. 153 * - "xx" fails. 154 */ 155 static bool parse_xy(const char *s, unsigned long *x, unsigned long *y) 156 { 157 unsigned long new_x = *x; 158 unsigned long new_y = *y; 159 char *p; 160 161 for (;;) { 162 if (!*s) 163 return false; 164 165 if (*s == ';') 166 break; 167 168 if (*s == 'x') { 169 new_x = simple_strtoul(s + 1, &p, 10); 170 if (p == s + 1) 171 return false; 172 s = p; 173 } else if (*s == 'y') { 174 new_y = simple_strtoul(s + 1, &p, 10); 175 if (p == s + 1) 176 return false; 177 s = p; 178 } else { 179 return false; 180 } 181 } 182 183 *x = new_x; 184 *y = new_y; 185 return true; 186 } 187 188 /* 189 * These are the file operation function for user access to /dev/lcd 190 * This function can also be called from inside the kernel, by 191 * setting file and ppos to NULL. 192 * 193 */ 194 195 static inline int handle_lcd_special_code(struct charlcd *lcd) 196 { 197 struct charlcd_priv *priv = charlcd_to_priv(lcd); 198 199 /* LCD special codes */ 200 201 int processed = 0; 202 203 char *esc = priv->esc_seq.buf + 2; 204 int oldflags = priv->flags; 205 206 /* check for display mode flags */ 207 switch (*esc) { 208 case 'D': /* Display ON */ 209 priv->flags |= LCD_FLAG_D; 210 if (priv->flags != oldflags) 211 lcd->ops->display(lcd, CHARLCD_ON); 212 213 processed = 1; 214 break; 215 case 'd': /* Display OFF */ 216 priv->flags &= ~LCD_FLAG_D; 217 if (priv->flags != oldflags) 218 lcd->ops->display(lcd, CHARLCD_OFF); 219 220 processed = 1; 221 break; 222 case 'C': /* Cursor ON */ 223 priv->flags |= LCD_FLAG_C; 224 if (priv->flags != oldflags) 225 lcd->ops->cursor(lcd, CHARLCD_ON); 226 227 processed = 1; 228 break; 229 case 'c': /* Cursor OFF */ 230 priv->flags &= ~LCD_FLAG_C; 231 if (priv->flags != oldflags) 232 lcd->ops->cursor(lcd, CHARLCD_OFF); 233 234 processed = 1; 235 break; 236 case 'B': /* Blink ON */ 237 priv->flags |= LCD_FLAG_B; 238 if (priv->flags != oldflags) 239 lcd->ops->blink(lcd, CHARLCD_ON); 240 241 processed = 1; 242 break; 243 case 'b': /* Blink OFF */ 244 priv->flags &= ~LCD_FLAG_B; 245 if (priv->flags != oldflags) 246 lcd->ops->blink(lcd, CHARLCD_OFF); 247 248 processed = 1; 249 break; 250 case '+': /* Back light ON */ 251 priv->flags |= LCD_FLAG_L; 252 if (priv->flags != oldflags) 253 charlcd_backlight(lcd, CHARLCD_ON); 254 255 processed = 1; 256 break; 257 case '-': /* Back light OFF */ 258 priv->flags &= ~LCD_FLAG_L; 259 if (priv->flags != oldflags) 260 charlcd_backlight(lcd, CHARLCD_OFF); 261 262 processed = 1; 263 break; 264 case '*': /* Flash back light */ 265 charlcd_poke(lcd); 266 processed = 1; 267 break; 268 case 'f': /* Small Font */ 269 priv->flags &= ~LCD_FLAG_F; 270 if (priv->flags != oldflags) 271 lcd->ops->fontsize(lcd, CHARLCD_FONTSIZE_SMALL); 272 273 processed = 1; 274 break; 275 case 'F': /* Large Font */ 276 priv->flags |= LCD_FLAG_F; 277 if (priv->flags != oldflags) 278 lcd->ops->fontsize(lcd, CHARLCD_FONTSIZE_LARGE); 279 280 processed = 1; 281 break; 282 case 'n': /* One Line */ 283 priv->flags &= ~LCD_FLAG_N; 284 if (priv->flags != oldflags) 285 lcd->ops->lines(lcd, CHARLCD_LINES_1); 286 287 processed = 1; 288 break; 289 case 'N': /* Two Lines */ 290 priv->flags |= LCD_FLAG_N; 291 if (priv->flags != oldflags) 292 lcd->ops->lines(lcd, CHARLCD_LINES_2); 293 294 processed = 1; 295 break; 296 case 'l': /* Shift Cursor Left */ 297 if (lcd->addr.x > 0) { 298 if (!lcd->ops->shift_cursor(lcd, CHARLCD_SHIFT_LEFT)) 299 lcd->addr.x--; 300 } 301 302 processed = 1; 303 break; 304 case 'r': /* shift cursor right */ 305 if (lcd->addr.x < lcd->width) { 306 if (!lcd->ops->shift_cursor(lcd, CHARLCD_SHIFT_RIGHT)) 307 lcd->addr.x++; 308 } 309 310 processed = 1; 311 break; 312 case 'L': /* shift display left */ 313 lcd->ops->shift_display(lcd, CHARLCD_SHIFT_LEFT); 314 processed = 1; 315 break; 316 case 'R': /* shift display right */ 317 lcd->ops->shift_display(lcd, CHARLCD_SHIFT_RIGHT); 318 processed = 1; 319 break; 320 case 'k': { /* kill end of line */ 321 int x, xs, ys; 322 323 xs = lcd->addr.x; 324 ys = lcd->addr.y; 325 for (x = lcd->addr.x; x < lcd->width; x++) 326 lcd->ops->print(lcd, ' '); 327 328 /* restore cursor position */ 329 lcd->addr.x = xs; 330 lcd->addr.y = ys; 331 lcd->ops->gotoxy(lcd, lcd->addr.x, lcd->addr.y); 332 processed = 1; 333 break; 334 } 335 case 'I': /* reinitialize display */ 336 lcd->ops->init_display(lcd); 337 priv->flags = ((lcd->height > 1) ? LCD_FLAG_N : 0) | LCD_FLAG_D | 338 LCD_FLAG_C | LCD_FLAG_B; 339 processed = 1; 340 break; 341 case 'G': 342 if (lcd->ops->redefine_char) 343 processed = lcd->ops->redefine_char(lcd, esc); 344 else 345 processed = 1; 346 break; 347 348 case 'x': /* gotoxy : LxXXX[yYYY]; */ 349 case 'y': /* gotoxy : LyYYY[xXXX]; */ 350 if (priv->esc_seq.buf[priv->esc_seq.len - 1] != ';') 351 break; 352 353 /* If the command is valid, move to the new address */ 354 if (parse_xy(esc, &lcd->addr.x, &lcd->addr.y)) 355 lcd->ops->gotoxy(lcd, lcd->addr.x, lcd->addr.y); 356 357 /* Regardless of its validity, mark as processed */ 358 processed = 1; 359 break; 360 } 361 362 return processed; 363 } 364 365 static void charlcd_write_char(struct charlcd *lcd, char c) 366 { 367 struct charlcd_priv *priv = charlcd_to_priv(lcd); 368 369 /* first, we'll test if we're in escape mode */ 370 if ((c != '\n') && priv->esc_seq.len >= 0) { 371 /* yes, let's add this char to the buffer */ 372 priv->esc_seq.buf[priv->esc_seq.len++] = c; 373 priv->esc_seq.buf[priv->esc_seq.len] = '\0'; 374 } else { 375 /* aborts any previous escape sequence */ 376 priv->esc_seq.len = -1; 377 378 switch (c) { 379 case LCD_ESCAPE_CHAR: 380 /* start of an escape sequence */ 381 priv->esc_seq.len = 0; 382 priv->esc_seq.buf[priv->esc_seq.len] = '\0'; 383 break; 384 case '\b': 385 /* go back one char and clear it */ 386 if (lcd->addr.x > 0) { 387 /* back one char */ 388 if (!lcd->ops->shift_cursor(lcd, 389 CHARLCD_SHIFT_LEFT)) 390 lcd->addr.x--; 391 } 392 /* replace with a space */ 393 charlcd_print(lcd, ' '); 394 /* back one char again */ 395 if (!lcd->ops->shift_cursor(lcd, CHARLCD_SHIFT_LEFT)) 396 lcd->addr.x--; 397 398 break; 399 case '\f': 400 /* quickly clear the display */ 401 charlcd_clear_display(lcd); 402 break; 403 case '\n': 404 /* 405 * flush the remainder of the current line and 406 * go to the beginning of the next line 407 */ 408 for (; lcd->addr.x < lcd->width; lcd->addr.x++) 409 lcd->ops->print(lcd, ' '); 410 411 lcd->addr.x = 0; 412 lcd->addr.y = (lcd->addr.y + 1) % lcd->height; 413 lcd->ops->gotoxy(lcd, lcd->addr.x, lcd->addr.y); 414 break; 415 case '\r': 416 /* go to the beginning of the same line */ 417 lcd->addr.x = 0; 418 lcd->ops->gotoxy(lcd, lcd->addr.x, lcd->addr.y); 419 break; 420 case '\t': 421 /* print a space instead of the tab */ 422 charlcd_print(lcd, ' '); 423 break; 424 default: 425 /* simply print this char */ 426 charlcd_print(lcd, c); 427 break; 428 } 429 } 430 431 /* 432 * now we'll see if we're in an escape mode and if the current 433 * escape sequence can be understood. 434 */ 435 if (priv->esc_seq.len >= 2) { 436 int processed = 0; 437 438 if (!strcmp(priv->esc_seq.buf, "[2J")) { 439 /* clear the display */ 440 charlcd_clear_display(lcd); 441 processed = 1; 442 } else if (!strcmp(priv->esc_seq.buf, "[H")) { 443 /* cursor to home */ 444 charlcd_home(lcd); 445 processed = 1; 446 } 447 /* codes starting with ^[[L */ 448 else if ((priv->esc_seq.len >= 3) && 449 (priv->esc_seq.buf[0] == '[') && 450 (priv->esc_seq.buf[1] == 'L')) { 451 processed = handle_lcd_special_code(lcd); 452 } 453 454 /* LCD special escape codes */ 455 /* 456 * flush the escape sequence if it's been processed 457 * or if it is getting too long. 458 */ 459 if (processed || (priv->esc_seq.len >= LCD_ESCAPE_LEN)) 460 priv->esc_seq.len = -1; 461 } /* escape codes */ 462 } 463 464 static struct charlcd *the_charlcd; 465 466 static ssize_t charlcd_write(struct file *file, const char __user *buf, 467 size_t count, loff_t *ppos) 468 { 469 const char __user *tmp = buf; 470 char c; 471 472 for (; count-- > 0; (*ppos)++, tmp++) { 473 if (((count + 1) & 0x1f) == 0) { 474 /* 475 * charlcd_write() is invoked as a VFS->write() callback 476 * and as such it is always invoked from preemptible 477 * context and may sleep. 478 */ 479 cond_resched(); 480 } 481 482 if (get_user(c, tmp)) 483 return -EFAULT; 484 485 charlcd_write_char(the_charlcd, c); 486 } 487 488 return tmp - buf; 489 } 490 491 static int charlcd_open(struct inode *inode, struct file *file) 492 { 493 struct charlcd_priv *priv = charlcd_to_priv(the_charlcd); 494 int ret; 495 496 ret = -EBUSY; 497 if (!atomic_dec_and_test(&charlcd_available)) 498 goto fail; /* open only once at a time */ 499 500 ret = -EPERM; 501 if (file->f_mode & FMODE_READ) /* device is write-only */ 502 goto fail; 503 504 if (priv->must_clear) { 505 priv->lcd.ops->clear_display(&priv->lcd); 506 priv->must_clear = false; 507 priv->lcd.addr.x = 0; 508 priv->lcd.addr.y = 0; 509 } 510 return nonseekable_open(inode, file); 511 512 fail: 513 atomic_inc(&charlcd_available); 514 return ret; 515 } 516 517 static int charlcd_release(struct inode *inode, struct file *file) 518 { 519 atomic_inc(&charlcd_available); 520 return 0; 521 } 522 523 static const struct file_operations charlcd_fops = { 524 .write = charlcd_write, 525 .open = charlcd_open, 526 .release = charlcd_release, 527 .llseek = no_llseek, 528 }; 529 530 static struct miscdevice charlcd_dev = { 531 .minor = LCD_MINOR, 532 .name = "lcd", 533 .fops = &charlcd_fops, 534 }; 535 536 static void charlcd_puts(struct charlcd *lcd, const char *s) 537 { 538 const char *tmp = s; 539 int count = strlen(s); 540 541 for (; count-- > 0; tmp++) { 542 if (((count + 1) & 0x1f) == 0) 543 cond_resched(); 544 545 charlcd_write_char(lcd, *tmp); 546 } 547 } 548 549 #ifdef CONFIG_PANEL_BOOT_MESSAGE 550 #define LCD_INIT_TEXT CONFIG_PANEL_BOOT_MESSAGE 551 #else 552 #define LCD_INIT_TEXT "Linux-" UTS_RELEASE "\n" 553 #endif 554 555 #ifdef CONFIG_CHARLCD_BL_ON 556 #define LCD_INIT_BL "\x1b[L+" 557 #elif defined(CONFIG_CHARLCD_BL_FLASH) 558 #define LCD_INIT_BL "\x1b[L*" 559 #else 560 #define LCD_INIT_BL "\x1b[L-" 561 #endif 562 563 /* initialize the LCD driver */ 564 static int charlcd_init(struct charlcd *lcd) 565 { 566 struct charlcd_priv *priv = charlcd_to_priv(lcd); 567 int ret; 568 569 priv->flags = ((lcd->height > 1) ? LCD_FLAG_N : 0) | LCD_FLAG_D | 570 LCD_FLAG_C | LCD_FLAG_B; 571 if (lcd->ops->backlight) { 572 mutex_init(&priv->bl_tempo_lock); 573 INIT_DELAYED_WORK(&priv->bl_work, charlcd_bl_off); 574 } 575 576 /* 577 * before this line, we must NOT send anything to the display. 578 * Since charlcd_init_display() needs to write data, we have to 579 * enable mark the LCD initialized just before. 580 */ 581 if (WARN_ON(!lcd->ops->init_display)) 582 return -EINVAL; 583 584 ret = lcd->ops->init_display(lcd); 585 if (ret) 586 return ret; 587 588 /* display a short message */ 589 charlcd_puts(lcd, "\x1b[Lc\x1b[Lb" LCD_INIT_BL LCD_INIT_TEXT); 590 591 /* clear the display on the next device opening */ 592 priv->must_clear = true; 593 charlcd_home(lcd); 594 return 0; 595 } 596 597 struct charlcd *charlcd_alloc(void) 598 { 599 struct charlcd_priv *priv; 600 struct charlcd *lcd; 601 602 priv = kzalloc(sizeof(*priv), GFP_KERNEL); 603 if (!priv) 604 return NULL; 605 606 priv->esc_seq.len = -1; 607 608 lcd = &priv->lcd; 609 610 return lcd; 611 } 612 EXPORT_SYMBOL_GPL(charlcd_alloc); 613 614 void charlcd_free(struct charlcd *lcd) 615 { 616 kfree(charlcd_to_priv(lcd)); 617 } 618 EXPORT_SYMBOL_GPL(charlcd_free); 619 620 static int panel_notify_sys(struct notifier_block *this, unsigned long code, 621 void *unused) 622 { 623 struct charlcd *lcd = the_charlcd; 624 625 switch (code) { 626 case SYS_DOWN: 627 charlcd_puts(lcd, 628 "\x0cReloading\nSystem...\x1b[Lc\x1b[Lb\x1b[L+"); 629 break; 630 case SYS_HALT: 631 charlcd_puts(lcd, "\x0cSystem Halted.\x1b[Lc\x1b[Lb\x1b[L+"); 632 break; 633 case SYS_POWER_OFF: 634 charlcd_puts(lcd, "\x0cPower off.\x1b[Lc\x1b[Lb\x1b[L+"); 635 break; 636 default: 637 break; 638 } 639 return NOTIFY_DONE; 640 } 641 642 static struct notifier_block panel_notifier = { 643 .notifier_call = panel_notify_sys, 644 }; 645 646 int charlcd_register(struct charlcd *lcd) 647 { 648 int ret; 649 650 ret = charlcd_init(lcd); 651 if (ret) 652 return ret; 653 654 ret = misc_register(&charlcd_dev); 655 if (ret) 656 return ret; 657 658 the_charlcd = lcd; 659 register_reboot_notifier(&panel_notifier); 660 return 0; 661 } 662 EXPORT_SYMBOL_GPL(charlcd_register); 663 664 int charlcd_unregister(struct charlcd *lcd) 665 { 666 struct charlcd_priv *priv = charlcd_to_priv(lcd); 667 668 unregister_reboot_notifier(&panel_notifier); 669 charlcd_puts(lcd, "\x0cLCD driver unloaded.\x1b[Lc\x1b[Lb\x1b[L-"); 670 misc_deregister(&charlcd_dev); 671 the_charlcd = NULL; 672 if (lcd->ops->backlight) { 673 cancel_delayed_work_sync(&priv->bl_work); 674 priv->lcd.ops->backlight(&priv->lcd, CHARLCD_OFF); 675 } 676 677 return 0; 678 } 679 EXPORT_SYMBOL_GPL(charlcd_unregister); 680 681 MODULE_LICENSE("GPL"); 682