drivers/auxdisplay/charlcd.c

   1 /*
   2  * Character LCD driver for Linux
   3  *
   4  * Copyright (C) 2000-2008, Willy Tarreau <w@1wt.eu>
   5  * Copyright (C) 2016-2017 Glider bvba
   6  *
   7  * This program is free software; you can redistribute it and/or
   8  * modify it under the terms of the GNU General Public License
   9  * as published by the Free Software Foundation; either version
  10  * 2 of the License, or (at your option) any later version.
  11  */
  12
  13 #include <linux/atomic.h>
  14 #include <linux/delay.h>
  15 #include <linux/fs.h>
  16 #include <linux/miscdevice.h>
  17 #include <linux/module.h>
  18 #include <linux/notifier.h>
  19 #include <linux/reboot.h>
  20 #include <linux/slab.h>
  21 #include <linux/uaccess.h>
  22 #include <linux/workqueue.h>
  23
  24 #include <generated/utsrelease.h>
  25
  26 #include <misc/charlcd.h>
  27
  28 #define LCD_MINOR               156
  29
  30 #define DEFAULT_LCD_BWIDTH      40
  31 #define DEFAULT_LCD_HWIDTH      64
  32
  33 /* Keep the backlight on this many seconds for each flash */
  34 #define LCD_BL_TEMPO_PERIOD     4
  35
  36 #define LCD_FLAG_B              0x0004  /* Blink on */
  37 #define LCD_FLAG_C              0x0008  /* Cursor on */
  38 #define LCD_FLAG_D              0x0010  /* Display on */
  39 #define LCD_FLAG_F              0x0020  /* Large font mode */
  40 #define LCD_FLAG_N              0x0040  /* 2-rows mode */
  41 #define LCD_FLAG_L              0x0080  /* Backlight enabled */
  42
  43 /* LCD commands */
  44 #define LCD_CMD_DISPLAY_CLEAR   0x01    /* Clear entire display */
  45
  46 #define LCD_CMD_ENTRY_MODE      0x04    /* Set entry mode */
  47 #define LCD_CMD_CURSOR_INC      0x02    /* Increment cursor */
  48
  49 #define LCD_CMD_DISPLAY_CTRL    0x08    /* Display control */
  50 #define LCD_CMD_DISPLAY_ON      0x04    /* Set display on */
  51 #define LCD_CMD_CURSOR_ON       0x02    /* Set cursor on */
  52 #define LCD_CMD_BLINK_ON        0x01    /* Set blink on */
  53
  54 #define LCD_CMD_SHIFT           0x10    /* Shift cursor/display */
  55 #define LCD_CMD_DISPLAY_SHIFT   0x08    /* Shift display instead of cursor */
  56 #define LCD_CMD_SHIFT_RIGHT     0x04    /* Shift display/cursor to the right */
  57
  58 #define LCD_CMD_FUNCTION_SET    0x20    /* Set function */
  59 #define LCD_CMD_DATA_LEN_8BITS  0x10    /* Set data length to 8 bits */
  60 #define LCD_CMD_TWO_LINES       0x08    /* Set to two display lines */
  61 #define LCD_CMD_FONT_5X10_DOTS  0x04    /* Set char font to 5x10 dots */
  62
  63 #define LCD_CMD_SET_CGRAM_ADDR  0x40    /* Set char generator RAM address */
  64
  65 #define LCD_CMD_SET_DDRAM_ADDR  0x80    /* Set display data RAM address */
  66
  67 #define LCD_ESCAPE_LEN          24      /* Max chars for LCD escape command */
  68 #define LCD_ESCAPE_CHAR         27      /* Use char 27 for escape command */
  69
  70 struct charlcd_priv {
  71         struct charlcd lcd;
  72
  73         struct delayed_work bl_work;
  74         struct mutex bl_tempo_lock;     /* Protects access to bl_tempo */
  75         bool bl_tempo;
  76
  77         bool must_clear;
  78
  79         /* contains the LCD config state */
  80         unsigned long int flags;
  81
  82         /* Contains the LCD X and Y offset */
  83         struct {
  84                 unsigned long int x;
  85                 unsigned long int y;
  86         } addr;
  87
  88         /* Current escape sequence and it's length or -1 if outside */
  89         struct {
  90                 char buf[LCD_ESCAPE_LEN + 1];
  91                 int len;
  92         } esc_seq;
  93
  94         unsigned long long drvdata[0];
  95 };
  96
  97 #define to_priv(p)      container_of(p, struct charlcd_priv, lcd)
  98
  99 /* Device single-open policy control */
 100 static atomic_t charlcd_available = ATOMIC_INIT(1);
 101
 102 /* sleeps that many milliseconds with a reschedule */
 103 static void long_sleep(int ms)
 104 {
 105         if (in_interrupt())
 106                 mdelay(ms);
 107         else
 108                 schedule_timeout_interruptible(msecs_to_jiffies(ms));
 109 }
 110
 111 /* turn the backlight on or off */
 112 static void charlcd_backlight(struct charlcd *lcd, int on)
 113 {
 114         struct charlcd_priv *priv = to_priv(lcd);
 115
 116         if (!lcd->ops->backlight)
 117                 return;
 118
 119         mutex_lock(&priv->bl_tempo_lock);
 120         if (!priv->bl_tempo)
 121                 lcd->ops->backlight(lcd, on);
 122         mutex_unlock(&priv->bl_tempo_lock);
 123 }
 124
 125 static void charlcd_bl_off(struct work_struct *work)
 126 {
 127         struct delayed_work *dwork = to_delayed_work(work);
 128         struct charlcd_priv *priv =
 129                 container_of(dwork, struct charlcd_priv, bl_work);
 130
 131         mutex_lock(&priv->bl_tempo_lock);
 132         if (priv->bl_tempo) {
 133                 priv->bl_tempo = false;
 134                 if (!(priv->flags & LCD_FLAG_L))
 135                         priv->lcd.ops->backlight(&priv->lcd, 0);
 136         }
 137         mutex_unlock(&priv->bl_tempo_lock);
 138 }
 139
 140 /* turn the backlight on for a little while */
 141 void charlcd_poke(struct charlcd *lcd)
 142 {
 143         struct charlcd_priv *priv = to_priv(lcd);
 144
 145         if (!lcd->ops->backlight)
 146                 return;
 147
 148         cancel_delayed_work_sync(&priv->bl_work);
 149
 150         mutex_lock(&priv->bl_tempo_lock);
 151         if (!priv->bl_tempo && !(priv->flags & LCD_FLAG_L))
 152                 lcd->ops->backlight(lcd, 1);
 153         priv->bl_tempo = true;
 154         schedule_delayed_work(&priv->bl_work, LCD_BL_TEMPO_PERIOD * HZ);
 155         mutex_unlock(&priv->bl_tempo_lock);
 156 }
 157 EXPORT_SYMBOL_GPL(charlcd_poke);
 158
 159 static void charlcd_gotoxy(struct charlcd *lcd)
 160 {
 161         struct charlcd_priv *priv = to_priv(lcd);
 162         unsigned int addr;
 163
 164         /*
 165          * we force the cursor to stay at the end of the
 166          * line if it wants to go farther
 167          */
 168         addr = priv->addr.x < lcd->bwidth ? priv->addr.x & (lcd->hwidth - 1)
 169                                           : lcd->bwidth - 1;
 170         if (priv->addr.y & 1)
 171                 addr += lcd->hwidth;
 172         if (priv->addr.y & 2)
 173                 addr += lcd->bwidth;
 174         lcd->ops->write_cmd(lcd, LCD_CMD_SET_DDRAM_ADDR | addr);
 175 }
 176
 177 static void charlcd_home(struct charlcd *lcd)
 178 {
 179         struct charlcd_priv *priv = to_priv(lcd);
 180
 181         priv->addr.x = 0;
 182         priv->addr.y = 0;
 183         charlcd_gotoxy(lcd);
 184 }
 185
 186 static void charlcd_print(struct charlcd *lcd, char c)
 187 {
 188         struct charlcd_priv *priv = to_priv(lcd);
 189
 190         if (priv->addr.x < lcd->bwidth) {
 191                 if (lcd->char_conv)
 192                         c = lcd->char_conv[(unsigned char)c];
 193                 lcd->ops->write_data(lcd, c);
 194                 priv->addr.x++;
 195         }
 196         /* prevents the cursor from wrapping onto the next line */
 197         if (priv->addr.x == lcd->bwidth)
 198                 charlcd_gotoxy(lcd);
 199 }
 200
 201 static void charlcd_clear_fast(struct charlcd *lcd)
 202 {
 203         int pos;
 204
 205         charlcd_home(lcd);
 206
 207         if (lcd->ops->clear_fast)
 208                 lcd->ops->clear_fast(lcd);
 209         else
 210                 for (pos = 0; pos < min(2, lcd->height) * lcd->hwidth; pos++)
 211                         lcd->ops->write_data(lcd, ' ');
 212
 213         charlcd_home(lcd);
 214 }
 215
 216 /* clears the display and resets X/Y */
 217 static void charlcd_clear_display(struct charlcd *lcd)
 218 {
 219         struct charlcd_priv *priv = to_priv(lcd);
 220
 221         lcd->ops->write_cmd(lcd, LCD_CMD_DISPLAY_CLEAR);
 222         priv->addr.x = 0;
 223         priv->addr.y = 0;
 224         /* we must wait a few milliseconds (15) */
 225         long_sleep(15);
 226 }
 227
 228 static int charlcd_init_display(struct charlcd *lcd)
 229 {
 230         void (*write_cmd_raw)(struct charlcd *lcd, int cmd);
 231         struct charlcd_priv *priv = to_priv(lcd);
 232         u8 init;
 233
 234         if (lcd->ifwidth != 4 && lcd->ifwidth != 8)
 235                 return -EINVAL;
 236
 237         priv->flags = ((lcd->height > 1) ? LCD_FLAG_N : 0) | LCD_FLAG_D |
 238                       LCD_FLAG_C | LCD_FLAG_B;
 239
 240         long_sleep(20);         /* wait 20 ms after power-up for the paranoid */
 241
 242         /*
 243          * 8-bit mode, 1 line, small fonts; let's do it 3 times, to make sure
 244          * the LCD is in 8-bit mode afterwards
 245          */
 246         init = LCD_CMD_FUNCTION_SET | LCD_CMD_DATA_LEN_8BITS;
 247         if (lcd->ifwidth == 4) {
 248                 init >>= 4;
 249                 write_cmd_raw = lcd->ops->write_cmd_raw4;
 250         } else {
 251                 write_cmd_raw = lcd->ops->write_cmd;
 252         }
 253         write_cmd_raw(lcd, init);
 254         long_sleep(10);
 255         write_cmd_raw(lcd, init);
 256         long_sleep(10);
 257         write_cmd_raw(lcd, init);
 258         long_sleep(10);
 259
 260         if (lcd->ifwidth == 4) {
 261                 /* Switch to 4-bit mode, 1 line, small fonts */
 262                 lcd->ops->write_cmd_raw4(lcd, LCD_CMD_FUNCTION_SET >> 4);
 263                 long_sleep(10);
 264         }
 265
 266         /* set font height and lines number */
 267         lcd->ops->write_cmd(lcd,
 268                 LCD_CMD_FUNCTION_SET |
 269                 ((lcd->ifwidth == 8) ? LCD_CMD_DATA_LEN_8BITS : 0) |
 270                 ((priv->flags & LCD_FLAG_F) ? LCD_CMD_FONT_5X10_DOTS : 0) |
 271                 ((priv->flags & LCD_FLAG_N) ? LCD_CMD_TWO_LINES : 0));
 272         long_sleep(10);
 273
 274         /* display off, cursor off, blink off */
 275         lcd->ops->write_cmd(lcd, LCD_CMD_DISPLAY_CTRL);
 276         long_sleep(10);
 277
 278         lcd->ops->write_cmd(lcd,
 279                 LCD_CMD_DISPLAY_CTRL |  /* set display mode */
 280                 ((priv->flags & LCD_FLAG_D) ? LCD_CMD_DISPLAY_ON : 0) |
 281                 ((priv->flags & LCD_FLAG_C) ? LCD_CMD_CURSOR_ON : 0) |
 282                 ((priv->flags & LCD_FLAG_B) ? LCD_CMD_BLINK_ON : 0));
 283
 284         charlcd_backlight(lcd, (priv->flags & LCD_FLAG_L) ? 1 : 0);
 285
 286         long_sleep(10);
 287
 288         /* entry mode set : increment, cursor shifting */
 289         lcd->ops->write_cmd(lcd, LCD_CMD_ENTRY_MODE | LCD_CMD_CURSOR_INC);
 290
 291         charlcd_clear_display(lcd);
 292         return 0;
 293 }
 294
 295 /*
 296  * These are the file operation function for user access to /dev/lcd
 297  * This function can also be called from inside the kernel, by
 298  * setting file and ppos to NULL.
 299  *
 300  */
 301
 302 static inline int handle_lcd_special_code(struct charlcd *lcd)
 303 {
 304         struct charlcd_priv *priv = to_priv(lcd);
 305
 306         /* LCD special codes */
 307
 308         int processed = 0;
 309
 310         char *esc = priv->esc_seq.buf + 2;
 311         int oldflags = priv->flags;
 312
 313         /* check for display mode flags */
 314         switch (*esc) {
 315         case 'D':       /* Display ON */
 316                 priv->flags |= LCD_FLAG_D;
 317                 processed = 1;
 318                 break;
 319         case 'd':       /* Display OFF */
 320                 priv->flags &= ~LCD_FLAG_D;
 321                 processed = 1;
 322                 break;
 323         case 'C':       /* Cursor ON */
 324                 priv->flags |= LCD_FLAG_C;
 325                 processed = 1;
 326                 break;
 327         case 'c':       /* Cursor OFF */
 328                 priv->flags &= ~LCD_FLAG_C;
 329                 processed = 1;
 330                 break;
 331         case 'B':       /* Blink ON */
 332                 priv->flags |= LCD_FLAG_B;
 333                 processed = 1;
 334                 break;
 335         case 'b':       /* Blink OFF */
 336                 priv->flags &= ~LCD_FLAG_B;
 337                 processed = 1;
 338                 break;
 339         case '+':       /* Back light ON */
 340                 priv->flags |= LCD_FLAG_L;
 341                 processed = 1;
 342                 break;
 343         case '-':       /* Back light OFF */
 344                 priv->flags &= ~LCD_FLAG_L;
 345                 processed = 1;
 346                 break;
 347         case '*':       /* Flash back light */
 348                 charlcd_poke(lcd);
 349                 processed = 1;
 350                 break;
 351         case 'f':       /* Small Font */
 352                 priv->flags &= ~LCD_FLAG_F;
 353                 processed = 1;
 354                 break;
 355         case 'F':       /* Large Font */
 356                 priv->flags |= LCD_FLAG_F;
 357                 processed = 1;
 358                 break;
 359         case 'n':       /* One Line */
 360                 priv->flags &= ~LCD_FLAG_N;
 361                 processed = 1;
 362                 break;
 363         case 'N':       /* Two Lines */
 364                 priv->flags |= LCD_FLAG_N;
 365                 break;
 366         case 'l':       /* Shift Cursor Left */
 367                 if (priv->addr.x > 0) {
 368                         /* back one char if not at end of line */
 369                         if (priv->addr.x < lcd->bwidth)
 370                                 lcd->ops->write_cmd(lcd, LCD_CMD_SHIFT);
 371                         priv->addr.x--;
 372                 }
 373                 processed = 1;
 374                 break;
 375         case 'r':       /* shift cursor right */
 376                 if (priv->addr.x < lcd->width) {
 377                         /* allow the cursor to pass the end of the line */
 378                         if (priv->addr.x < (lcd->bwidth - 1))
 379                                 lcd->ops->write_cmd(lcd,
 380                                         LCD_CMD_SHIFT | LCD_CMD_SHIFT_RIGHT);
 381                         priv->addr.x++;
 382                 }
 383                 processed = 1;
 384                 break;
 385         case 'L':       /* shift display left */
 386                 lcd->ops->write_cmd(lcd, LCD_CMD_SHIFT | LCD_CMD_DISPLAY_SHIFT);
 387                 processed = 1;
 388                 break;
 389         case 'R':       /* shift display right */
 390                 lcd->ops->write_cmd(lcd,
 391                                     LCD_CMD_SHIFT | LCD_CMD_DISPLAY_SHIFT |
 392                                     LCD_CMD_SHIFT_RIGHT);
 393                 processed = 1;
 394                 break;
 395         case 'k': {     /* kill end of line */
 396                 int x;
 397
 398                 for (x = priv->addr.x; x < lcd->bwidth; x++)
 399                         lcd->ops->write_data(lcd, ' ');
 400
 401                 /* restore cursor position */
 402                 charlcd_gotoxy(lcd);
 403                 processed = 1;
 404                 break;
 405         }
 406         case 'I':       /* reinitialize display */
 407                 charlcd_init_display(lcd);
 408                 processed = 1;
 409                 break;
 410         case 'G': {
 411                 /* Generator : LGcxxxxx...xx; must have <c> between '0'
 412                  * and '7', representing the numerical ASCII code of the
 413                  * redefined character, and <xx...xx> a sequence of 16
 414                  * hex digits representing 8 bytes for each character.
 415                  * Most LCDs will only use 5 lower bits of the 7 first
 416                  * bytes.
 417                  */
 418
 419                 unsigned char cgbytes[8];
 420                 unsigned char cgaddr;
 421                 int cgoffset;
 422                 int shift;
 423                 char value;
 424                 int addr;
 425
 426                 if (!strchr(esc, ';'))
 427                         break;
 428
 429                 esc++;
 430
 431                 cgaddr = *(esc++) - '0';
 432                 if (cgaddr > 7) {
 433                         processed = 1;
 434                         break;
 435                 }
 436
 437                 cgoffset = 0;
 438                 shift = 0;
 439                 value = 0;
 440                 while (*esc && cgoffset < 8) {
 441                         shift ^= 4;
 442                         if (*esc >= '0' && *esc <= '9') {
 443                                 value |= (*esc - '0') << shift;
 444                         } else if (*esc >= 'A' && *esc <= 'Z') {
 445                                 value |= (*esc - 'A' + 10) << shift;
 446                         } else if (*esc >= 'a' && *esc <= 'z') {
 447                                 value |= (*esc - 'a' + 10) << shift;
 448                         } else {
 449                                 esc++;
 450                                 continue;
 451                         }
 452
 453                         if (shift == 0) {
 454                                 cgbytes[cgoffset++] = value;
 455                                 value = 0;
 456                         }
 457
 458                         esc++;
 459                 }
 460
 461                 lcd->ops->write_cmd(lcd, LCD_CMD_SET_CGRAM_ADDR | (cgaddr * 8));
 462                 for (addr = 0; addr < cgoffset; addr++)
 463                         lcd->ops->write_data(lcd, cgbytes[addr]);
 464
 465                 /* ensures that we stop writing to CGRAM */
 466                 charlcd_gotoxy(lcd);
 467                 processed = 1;
 468                 break;
 469         }
 470         case 'x':       /* gotoxy : LxXXX[yYYY]; */
 471         case 'y':       /* gotoxy : LyYYY[xXXX]; */
 472                 if (!strchr(esc, ';'))
 473                         break;
 474
 475                 while (*esc) {
 476                         if (*esc == 'x') {
 477                                 esc++;
 478                                 if (kstrtoul(esc, 10, &priv->addr.x) < 0)
 479                                         break;
 480                         } else if (*esc == 'y') {
 481                                 esc++;
 482                                 if (kstrtoul(esc, 10, &priv->addr.y) < 0)
 483                                         break;
 484                         } else {
 485                                 break;
 486                         }
 487                 }
 488
 489                 charlcd_gotoxy(lcd);
 490                 processed = 1;
 491                 break;
 492         }
 493
 494         /* TODO: This indent party here got ugly, clean it! */
 495         /* Check whether one flag was changed */
 496         if (oldflags == priv->flags)
 497                 return processed;
 498
 499         /* check whether one of B,C,D flags were changed */
 500         if ((oldflags ^ priv->flags) &
 501             (LCD_FLAG_B | LCD_FLAG_C | LCD_FLAG_D))
 502                 /* set display mode */
 503                 lcd->ops->write_cmd(lcd,
 504                         LCD_CMD_DISPLAY_CTRL |
 505                         ((priv->flags & LCD_FLAG_D) ? LCD_CMD_DISPLAY_ON : 0) |
 506                         ((priv->flags & LCD_FLAG_C) ? LCD_CMD_CURSOR_ON : 0) |
 507                         ((priv->flags & LCD_FLAG_B) ? LCD_CMD_BLINK_ON : 0));
 508         /* check whether one of F,N flags was changed */
 509         else if ((oldflags ^ priv->flags) & (LCD_FLAG_F | LCD_FLAG_N))
 510                 lcd->ops->write_cmd(lcd,
 511                         LCD_CMD_FUNCTION_SET |
 512                         ((lcd->ifwidth == 8) ? LCD_CMD_DATA_LEN_8BITS : 0) |
 513                         ((priv->flags & LCD_FLAG_F) ? LCD_CMD_FONT_5X10_DOTS : 0) |
 514                         ((priv->flags & LCD_FLAG_N) ? LCD_CMD_TWO_LINES : 0));
 515         /* check whether L flag was changed */
 516         else if ((oldflags ^ priv->flags) & LCD_FLAG_L)
 517                 charlcd_backlight(lcd, !!(priv->flags & LCD_FLAG_L));
 518
 519         return processed;
 520 }
 521
 522 static void charlcd_write_char(struct charlcd *lcd, char c)
 523 {
 524         struct charlcd_priv *priv = to_priv(lcd);
 525
 526         /* first, we'll test if we're in escape mode */
 527         if ((c != '\n') && priv->esc_seq.len >= 0) {
 528                 /* yes, let's add this char to the buffer */
 529                 priv->esc_seq.buf[priv->esc_seq.len++] = c;
 530                 priv->esc_seq.buf[priv->esc_seq.len] = 0;
 531         } else {
 532                 /* aborts any previous escape sequence */
 533                 priv->esc_seq.len = -1;
 534
 535                 switch (c) {
 536                 case LCD_ESCAPE_CHAR:
 537                         /* start of an escape sequence */
 538                         priv->esc_seq.len = 0;
 539                         priv->esc_seq.buf[priv->esc_seq.len] = 0;
 540                         break;
 541                 case '\b':
 542                         /* go back one char and clear it */
 543                         if (priv->addr.x > 0) {
 544                                 /*
 545                                  * check if we're not at the
 546                                  * end of the line
 547                                  */
 548                                 if (priv->addr.x < lcd->bwidth)
 549                                         /* back one char */
 550                                         lcd->ops->write_cmd(lcd, LCD_CMD_SHIFT);
 551                                 priv->addr.x--;
 552                         }
 553                         /* replace with a space */
 554                         lcd->ops->write_data(lcd, ' ');
 555                         /* back one char again */
 556                         lcd->ops->write_cmd(lcd, LCD_CMD_SHIFT);
 557                         break;
 558                 case '\014':
 559                         /* quickly clear the display */
 560                         charlcd_clear_fast(lcd);
 561                         break;
 562                 case '\n':
 563                         /*
 564                          * flush the remainder of the current line and
 565                          * go to the beginning of the next line
 566                          */
 567                         for (; priv->addr.x < lcd->bwidth; priv->addr.x++)
 568                                 lcd->ops->write_data(lcd, ' ');
 569                         priv->addr.x = 0;
 570                         priv->addr.y = (priv->addr.y + 1) % lcd->height;
 571                         charlcd_gotoxy(lcd);
 572                         break;
 573                 case '\r':
 574                         /* go to the beginning of the same line */
 575                         priv->addr.x = 0;
 576                         charlcd_gotoxy(lcd);
 577                         break;
 578                 case '\t':
 579                         /* print a space instead of the tab */
 580                         charlcd_print(lcd, ' ');
 581                         break;
 582                 default:
 583                         /* simply print this char */
 584                         charlcd_print(lcd, c);
 585                         break;
 586                 }
 587         }
 588
 589         /*
 590          * now we'll see if we're in an escape mode and if the current
 591          * escape sequence can be understood.
 592          */
 593         if (priv->esc_seq.len >= 2) {
 594                 int processed = 0;
 595
 596                 if (!strcmp(priv->esc_seq.buf, "[2J")) {
 597                         /* clear the display */
 598                         charlcd_clear_fast(lcd);
 599                         processed = 1;
 600                 } else if (!strcmp(priv->esc_seq.buf, "[H")) {
 601                         /* cursor to home */
 602                         charlcd_home(lcd);
 603                         processed = 1;
 604                 }
 605                 /* codes starting with ^[[L */
 606                 else if ((priv->esc_seq.len >= 3) &&
 607                          (priv->esc_seq.buf[0] == '[') &&
 608                          (priv->esc_seq.buf[1] == 'L')) {
 609                         processed = handle_lcd_special_code(lcd);
 610                 }
 611
 612                 /* LCD special escape codes */
 613                 /*
 614                  * flush the escape sequence if it's been processed
 615                  * or if it is getting too long.
 616                  */
 617                 if (processed || (priv->esc_seq.len >= LCD_ESCAPE_LEN))
 618                         priv->esc_seq.len = -1;
 619         } /* escape codes */
 620 }
 621
 622 static struct charlcd *the_charlcd;
 623
 624 static ssize_t charlcd_write(struct file *file, const char __user *buf,
 625                              size_t count, loff_t *ppos)
 626 {
 627         const char __user *tmp = buf;
 628         char c;
 629
 630         for (; count-- > 0; (*ppos)++, tmp++) {
 631                 if (!in_interrupt() && (((count + 1) & 0x1f) == 0))
 632                         /*
 633                          * let's be a little nice with other processes
 634                          * that need some CPU
 635                          */
 636                         schedule();
 637
 638                 if (get_user(c, tmp))
 639                         return -EFAULT;
 640
 641                 charlcd_write_char(the_charlcd, c);
 642         }
 643
 644         return tmp - buf;
 645 }
 646
 647 static int charlcd_open(struct inode *inode, struct file *file)
 648 {
 649         struct charlcd_priv *priv = to_priv(the_charlcd);
 650
 651         if (!atomic_dec_and_test(&charlcd_available))
 652                 return -EBUSY;  /* open only once at a time */
 653
 654         if (file->f_mode & FMODE_READ)  /* device is write-only */
 655                 return -EPERM;
 656
 657         if (priv->must_clear) {
 658                 charlcd_clear_display(&priv->lcd);
 659                 priv->must_clear = false;
 660         }
 661         return nonseekable_open(inode, file);
 662 }
 663
 664 static int charlcd_release(struct inode *inode, struct file *file)
 665 {
 666         atomic_inc(&charlcd_available);
 667         return 0;
 668 }
 669
 670 static const struct file_operations charlcd_fops = {
 671         .write   = charlcd_write,
 672         .open    = charlcd_open,
 673         .release = charlcd_release,
 674         .llseek  = no_llseek,
 675 };
 676
 677 static struct miscdevice charlcd_dev = {
 678         .minor  = LCD_MINOR,
 679         .name   = "lcd",
 680         .fops   = &charlcd_fops,
 681 };
 682
 683 static void charlcd_puts(struct charlcd *lcd, const char *s)
 684 {
 685         const char *tmp = s;
 686         int count = strlen(s);
 687
 688         for (; count-- > 0; tmp++) {
 689                 if (!in_interrupt() && (((count + 1) & 0x1f) == 0))
 690                         /*
 691                          * let's be a little nice with other processes
 692                          * that need some CPU
 693                          */
 694                         schedule();
 695
 696                 charlcd_write_char(lcd, *tmp);
 697         }
 698 }
 699
 700 /* initialize the LCD driver */
 701 static int charlcd_init(struct charlcd *lcd)
 702 {
 703         struct charlcd_priv *priv = to_priv(lcd);
 704         int ret;
 705
 706         if (lcd->ops->backlight) {
 707                 mutex_init(&priv->bl_tempo_lock);
 708                 INIT_DELAYED_WORK(&priv->bl_work, charlcd_bl_off);
 709         }
 710
 711         /*
 712          * before this line, we must NOT send anything to the display.
 713          * Since charlcd_init_display() needs to write data, we have to
 714          * enable mark the LCD initialized just before.
 715          */
 716         ret = charlcd_init_display(lcd);
 717         if (ret)
 718                 return ret;
 719
 720         /* display a short message */
 721 #ifdef CONFIG_PANEL_CHANGE_MESSAGE
 722 #ifdef CONFIG_PANEL_BOOT_MESSAGE
 723         charlcd_puts(lcd, "\x1b[Lc\x1b[Lb\x1b[L*" CONFIG_PANEL_BOOT_MESSAGE);
 724 #endif
 725 #else
 726         charlcd_puts(lcd, "\x1b[Lc\x1b[Lb\x1b[L*Linux-" UTS_RELEASE "\n");
 727 #endif
 728         /* clear the display on the next device opening */
 729         priv->must_clear = true;
 730         charlcd_home(lcd);
 731         return 0;
 732 }
 733
 734 struct charlcd *charlcd_alloc(unsigned int drvdata_size)
 735 {
 736         struct charlcd_priv *priv;
 737         struct charlcd *lcd;
 738
 739         priv = kzalloc(sizeof(*priv) + drvdata_size, GFP_KERNEL);
 740         if (!priv)
 741                 return NULL;
 742
 743         priv->esc_seq.len = -1;
 744
 745         lcd = &priv->lcd;
 746         lcd->ifwidth = 8;
 747         lcd->bwidth = DEFAULT_LCD_BWIDTH;
 748         lcd->hwidth = DEFAULT_LCD_HWIDTH;
 749         lcd->drvdata = priv->drvdata;
 750
 751         return lcd;
 752 }
 753 EXPORT_SYMBOL_GPL(charlcd_alloc);
 754
 755 static int panel_notify_sys(struct notifier_block *this, unsigned long code,
 756                             void *unused)
 757 {
 758         struct charlcd *lcd = the_charlcd;
 759
 760         switch (code) {
 761         case SYS_DOWN:
 762                 charlcd_puts(lcd,
 763                              "\x0cReloading\nSystem...\x1b[Lc\x1b[Lb\x1b[L+");
 764                 break;
 765         case SYS_HALT:
 766                 charlcd_puts(lcd, "\x0cSystem Halted.\x1b[Lc\x1b[Lb\x1b[L+");
 767                 break;
 768         case SYS_POWER_OFF:
 769                 charlcd_puts(lcd, "\x0cPower off.\x1b[Lc\x1b[Lb\x1b[L+");
 770                 break;
 771         default:
 772                 break;
 773         }
 774         return NOTIFY_DONE;
 775 }
 776
 777 static struct notifier_block panel_notifier = {
 778         panel_notify_sys,
 779         NULL,
 780         0
 781 };
 782
 783 int charlcd_register(struct charlcd *lcd)
 784 {
 785         int ret;
 786
 787         ret = charlcd_init(lcd);
 788         if (ret)
 789                 return ret;
 790
 791         ret = misc_register(&charlcd_dev);
 792         if (ret)
 793                 return ret;
 794
 795         the_charlcd = lcd;
 796         register_reboot_notifier(&panel_notifier);
 797         return 0;
 798 }
 799 EXPORT_SYMBOL_GPL(charlcd_register);
 800
 801 int charlcd_unregister(struct charlcd *lcd)
 802 {
 803         struct charlcd_priv *priv = to_priv(lcd);
 804
 805         unregister_reboot_notifier(&panel_notifier);
 806         charlcd_puts(lcd, "\x0cLCD driver unloaded.\x1b[Lc\x1b[Lb\x1b[L-");
 807         misc_deregister(&charlcd_dev);
 808         the_charlcd = NULL;
 809         if (lcd->ops->backlight) {
 810                 cancel_delayed_work_sync(&priv->bl_work);
 811                 priv->lcd.ops->backlight(&priv->lcd, 0);
 812         }
 813
 814         return 0;
 815 }
 816 EXPORT_SYMBOL_GPL(charlcd_unregister);
 817
 818 MODULE_LICENSE("GPL");