drivers/auxdisplay/charlcd.c

   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");