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 "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[];
  92 };
  93
  94 #define charlcd_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         schedule_timeout_interruptible(msecs_to_jiffies(ms));
 103 }
 104
 105 /* turn the backlight on or off */
 106 static void charlcd_backlight(struct charlcd *lcd, int on)
 107 {
 108         struct charlcd_priv *priv = charlcd_to_priv(lcd);
 109
 110         if (!lcd->ops->backlight)
 111                 return;
 112
 113         mutex_lock(&priv->bl_tempo_lock);
 114         if (!priv->bl_tempo)
 115                 lcd->ops->backlight(lcd, on);
 116         mutex_unlock(&priv->bl_tempo_lock);
 117 }
 118
 119 static void charlcd_bl_off(struct work_struct *work)
 120 {
 121         struct delayed_work *dwork = to_delayed_work(work);
 122         struct charlcd_priv *priv =
 123                 container_of(dwork, struct charlcd_priv, bl_work);
 124
 125         mutex_lock(&priv->bl_tempo_lock);
 126         if (priv->bl_tempo) {
 127                 priv->bl_tempo = false;
 128                 if (!(priv->flags & LCD_FLAG_L))
 129                         priv->lcd.ops->backlight(&priv->lcd, 0);
 130         }
 131         mutex_unlock(&priv->bl_tempo_lock);
 132 }
 133
 134 /* turn the backlight on for a little while */
 135 void charlcd_poke(struct charlcd *lcd)
 136 {
 137         struct charlcd_priv *priv = charlcd_to_priv(lcd);
 138
 139         if (!lcd->ops->backlight)
 140                 return;
 141
 142         cancel_delayed_work_sync(&priv->bl_work);
 143
 144         mutex_lock(&priv->bl_tempo_lock);
 145         if (!priv->bl_tempo && !(priv->flags & LCD_FLAG_L))
 146                 lcd->ops->backlight(lcd, 1);
 147         priv->bl_tempo = true;
 148         schedule_delayed_work(&priv->bl_work, LCD_BL_TEMPO_PERIOD * HZ);
 149         mutex_unlock(&priv->bl_tempo_lock);
 150 }
 151 EXPORT_SYMBOL_GPL(charlcd_poke);
 152
 153 static void charlcd_gotoxy(struct charlcd *lcd)
 154 {
 155         struct charlcd_priv *priv = charlcd_to_priv(lcd);
 156         unsigned int addr;
 157
 158         /*
 159          * we force the cursor to stay at the end of the
 160          * line if it wants to go farther
 161          */
 162         addr = priv->addr.x < lcd->bwidth ? priv->addr.x & (lcd->hwidth - 1)
 163                                           : lcd->bwidth - 1;
 164         if (priv->addr.y & 1)
 165                 addr += lcd->hwidth;
 166         if (priv->addr.y & 2)
 167                 addr += lcd->bwidth;
 168         lcd->ops->write_cmd(lcd, LCD_CMD_SET_DDRAM_ADDR | addr);
 169 }
 170
 171 static void charlcd_home(struct charlcd *lcd)
 172 {
 173         struct charlcd_priv *priv = charlcd_to_priv(lcd);
 174
 175         priv->addr.x = 0;
 176         priv->addr.y = 0;
 177         charlcd_gotoxy(lcd);
 178 }
 179
 180 static void charlcd_print(struct charlcd *lcd, char c)
 181 {
 182         struct charlcd_priv *priv = charlcd_to_priv(lcd);
 183
 184         if (priv->addr.x < lcd->bwidth) {
 185                 if (lcd->char_conv)
 186                         c = lcd->char_conv[(unsigned char)c];
 187                 lcd->ops->write_data(lcd, c);
 188                 priv->addr.x++;
 189
 190                 /* prevents the cursor from wrapping onto the next line */
 191                 if (priv->addr.x == lcd->bwidth)
 192                         charlcd_gotoxy(lcd);
 193         }
 194 }
 195
 196 static void charlcd_clear_fast(struct charlcd *lcd)
 197 {
 198         int pos;
 199
 200         charlcd_home(lcd);
 201
 202         if (lcd->ops->clear_fast)
 203                 lcd->ops->clear_fast(lcd);
 204         else
 205                 for (pos = 0; pos < min(2, lcd->height) * lcd->hwidth; pos++)
 206                         lcd->ops->write_data(lcd, ' ');
 207
 208         charlcd_home(lcd);
 209 }
 210
 211 /* clears the display and resets X/Y */
 212 static void charlcd_clear_display(struct charlcd *lcd)
 213 {
 214         struct charlcd_priv *priv = charlcd_to_priv(lcd);
 215
 216         lcd->ops->write_cmd(lcd, LCD_CMD_DISPLAY_CLEAR);
 217         priv->addr.x = 0;
 218         priv->addr.y = 0;
 219         /* we must wait a few milliseconds (15) */
 220         long_sleep(15);
 221 }
 222
 223 static int charlcd_init_display(struct charlcd *lcd)
 224 {
 225         void (*write_cmd_raw)(struct charlcd *lcd, int cmd);
 226         struct charlcd_priv *priv = charlcd_to_priv(lcd);
 227         u8 init;
 228
 229         if (lcd->ifwidth != 4 && lcd->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 (lcd->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 (lcd->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                 ((lcd->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
 354         /* LCD special codes */
 355
 356         int processed = 0;
 357
 358         char *esc = priv->esc_seq.buf + 2;
 359         int oldflags = priv->flags;
 360
 361         /* check for display mode flags */
 362         switch (*esc) {
 363         case 'D':       /* Display ON */
 364                 priv->flags |= LCD_FLAG_D;
 365                 processed = 1;
 366                 break;
 367         case 'd':       /* Display OFF */
 368                 priv->flags &= ~LCD_FLAG_D;
 369                 processed = 1;
 370                 break;
 371         case 'C':       /* Cursor ON */
 372                 priv->flags |= LCD_FLAG_C;
 373                 processed = 1;
 374                 break;
 375         case 'c':       /* Cursor OFF */
 376                 priv->flags &= ~LCD_FLAG_C;
 377                 processed = 1;
 378                 break;
 379         case 'B':       /* Blink ON */
 380                 priv->flags |= LCD_FLAG_B;
 381                 processed = 1;
 382                 break;
 383         case 'b':       /* Blink OFF */
 384                 priv->flags &= ~LCD_FLAG_B;
 385                 processed = 1;
 386                 break;
 387         case '+':       /* Back light ON */
 388                 priv->flags |= LCD_FLAG_L;
 389                 processed = 1;
 390                 break;
 391         case '-':       /* Back light OFF */
 392                 priv->flags &= ~LCD_FLAG_L;
 393                 processed = 1;
 394                 break;
 395         case '*':       /* Flash back light */
 396                 charlcd_poke(lcd);
 397                 processed = 1;
 398                 break;
 399         case 'f':       /* Small Font */
 400                 priv->flags &= ~LCD_FLAG_F;
 401                 processed = 1;
 402                 break;
 403         case 'F':       /* Large Font */
 404                 priv->flags |= LCD_FLAG_F;
 405                 processed = 1;
 406                 break;
 407         case 'n':       /* One Line */
 408                 priv->flags &= ~LCD_FLAG_N;
 409                 processed = 1;
 410                 break;
 411         case 'N':       /* Two Lines */
 412                 priv->flags |= LCD_FLAG_N;
 413                 processed = 1;
 414                 break;
 415         case 'l':       /* Shift Cursor Left */
 416                 if (priv->addr.x > 0) {
 417                         /* back one char if not at end of line */
 418                         if (priv->addr.x < lcd->bwidth)
 419                                 lcd->ops->write_cmd(lcd, LCD_CMD_SHIFT);
 420                         priv->addr.x--;
 421                 }
 422                 processed = 1;
 423                 break;
 424         case 'r':       /* shift cursor right */
 425                 if (priv->addr.x < lcd->width) {
 426                         /* allow the cursor to pass the end of the line */
 427                         if (priv->addr.x < (lcd->bwidth - 1))
 428                                 lcd->ops->write_cmd(lcd,
 429                                         LCD_CMD_SHIFT | LCD_CMD_SHIFT_RIGHT);
 430                         priv->addr.x++;
 431                 }
 432                 processed = 1;
 433                 break;
 434         case 'L':       /* shift display left */
 435                 lcd->ops->write_cmd(lcd, LCD_CMD_SHIFT | LCD_CMD_DISPLAY_SHIFT);
 436                 processed = 1;
 437                 break;
 438         case 'R':       /* shift display right */
 439                 lcd->ops->write_cmd(lcd,
 440                                     LCD_CMD_SHIFT | LCD_CMD_DISPLAY_SHIFT |
 441                                     LCD_CMD_SHIFT_RIGHT);
 442                 processed = 1;
 443                 break;
 444         case 'k': {     /* kill end of line */
 445                 int x;
 446
 447                 for (x = priv->addr.x; x < lcd->bwidth; x++)
 448                         lcd->ops->write_data(lcd, ' ');
 449
 450                 /* restore cursor position */
 451                 charlcd_gotoxy(lcd);
 452                 processed = 1;
 453                 break;
 454         }
 455         case 'I':       /* reinitialize display */
 456                 charlcd_init_display(lcd);
 457                 processed = 1;
 458                 break;
 459         case 'G': {
 460                 /* Generator : LGcxxxxx...xx; must have <c> between '0'
 461                  * and '7', representing the numerical ASCII code of the
 462                  * redefined character, and <xx...xx> a sequence of 16
 463                  * hex digits representing 8 bytes for each character.
 464                  * Most LCDs will only use 5 lower bits of the 7 first
 465                  * bytes.
 466                  */
 467
 468                 unsigned char cgbytes[8];
 469                 unsigned char cgaddr;
 470                 int cgoffset;
 471                 int shift;
 472                 char value;
 473                 int addr;
 474
 475                 if (!strchr(esc, ';'))
 476                         break;
 477
 478                 esc++;
 479
 480                 cgaddr = *(esc++) - '0';
 481                 if (cgaddr > 7) {
 482                         processed = 1;
 483                         break;
 484                 }
 485
 486                 cgoffset = 0;
 487                 shift = 0;
 488                 value = 0;
 489                 while (*esc && cgoffset < 8) {
 490                         shift ^= 4;
 491                         if (*esc >= '0' && *esc <= '9') {
 492                                 value |= (*esc - '0') << shift;
 493                         } else if (*esc >= 'A' && *esc <= 'F') {
 494                                 value |= (*esc - 'A' + 10) << shift;
 495                         } else if (*esc >= 'a' && *esc <= 'f') {
 496                                 value |= (*esc - 'a' + 10) << shift;
 497                         } else {
 498                                 esc++;
 499                                 continue;
 500                         }
 501
 502                         if (shift == 0) {
 503                                 cgbytes[cgoffset++] = value;
 504                                 value = 0;
 505                         }
 506
 507                         esc++;
 508                 }
 509
 510                 lcd->ops->write_cmd(lcd, LCD_CMD_SET_CGRAM_ADDR | (cgaddr * 8));
 511                 for (addr = 0; addr < cgoffset; addr++)
 512                         lcd->ops->write_data(lcd, cgbytes[addr]);
 513
 514                 /* ensures that we stop writing to CGRAM */
 515                 charlcd_gotoxy(lcd);
 516                 processed = 1;
 517                 break;
 518         }
 519         case 'x':       /* gotoxy : LxXXX[yYYY]; */
 520         case 'y':       /* gotoxy : LyYYY[xXXX]; */
 521                 if (priv->esc_seq.buf[priv->esc_seq.len - 1] != ';')
 522                         break;
 523
 524                 /* If the command is valid, move to the new address */
 525                 if (parse_xy(esc, &priv->addr.x, &priv->addr.y))
 526                         charlcd_gotoxy(lcd);
 527
 528                 /* Regardless of its validity, mark as processed */
 529                 processed = 1;
 530                 break;
 531         }
 532
 533         /* TODO: This indent party here got ugly, clean it! */
 534         /* Check whether one flag was changed */
 535         if (oldflags == priv->flags)
 536                 return processed;
 537
 538         /* check whether one of B,C,D flags were changed */
 539         if ((oldflags ^ priv->flags) &
 540             (LCD_FLAG_B | LCD_FLAG_C | LCD_FLAG_D))
 541                 /* set display mode */
 542                 lcd->ops->write_cmd(lcd,
 543                         LCD_CMD_DISPLAY_CTRL |
 544                         ((priv->flags & LCD_FLAG_D) ? LCD_CMD_DISPLAY_ON : 0) |
 545                         ((priv->flags & LCD_FLAG_C) ? LCD_CMD_CURSOR_ON : 0) |
 546                         ((priv->flags & LCD_FLAG_B) ? LCD_CMD_BLINK_ON : 0));
 547         /* check whether one of F,N flags was changed */
 548         else if ((oldflags ^ priv->flags) & (LCD_FLAG_F | LCD_FLAG_N))
 549                 lcd->ops->write_cmd(lcd,
 550                         LCD_CMD_FUNCTION_SET |
 551                         ((lcd->ifwidth == 8) ? LCD_CMD_DATA_LEN_8BITS : 0) |
 552                         ((priv->flags & LCD_FLAG_F) ? LCD_CMD_FONT_5X10_DOTS : 0) |
 553                         ((priv->flags & LCD_FLAG_N) ? LCD_CMD_TWO_LINES : 0));
 554         /* check whether L flag was changed */
 555         else if ((oldflags ^ priv->flags) & LCD_FLAG_L)
 556                 charlcd_backlight(lcd, !!(priv->flags & LCD_FLAG_L));
 557
 558         return processed;
 559 }
 560
 561 static void charlcd_write_char(struct charlcd *lcd, char c)
 562 {
 563         struct charlcd_priv *priv = charlcd_to_priv(lcd);
 564
 565         /* first, we'll test if we're in escape mode */
 566         if ((c != '\n') && priv->esc_seq.len >= 0) {
 567                 /* yes, let's add this char to the buffer */
 568                 priv->esc_seq.buf[priv->esc_seq.len++] = c;
 569                 priv->esc_seq.buf[priv->esc_seq.len] = '\0';
 570         } else {
 571                 /* aborts any previous escape sequence */
 572                 priv->esc_seq.len = -1;
 573
 574                 switch (c) {
 575                 case LCD_ESCAPE_CHAR:
 576                         /* start of an escape sequence */
 577                         priv->esc_seq.len = 0;
 578                         priv->esc_seq.buf[priv->esc_seq.len] = '\0';
 579                         break;
 580                 case '\b':
 581                         /* go back one char and clear it */
 582                         if (priv->addr.x > 0) {
 583                                 /*
 584                                  * check if we're not at the
 585                                  * end of the line
 586                                  */
 587                                 if (priv->addr.x < lcd->bwidth)
 588                                         /* back one char */
 589                                         lcd->ops->write_cmd(lcd, LCD_CMD_SHIFT);
 590                                 priv->addr.x--;
 591                         }
 592                         /* replace with a space */
 593                         lcd->ops->write_data(lcd, ' ');
 594                         /* back one char again */
 595                         lcd->ops->write_cmd(lcd, LCD_CMD_SHIFT);
 596                         break;
 597                 case '\f':
 598                         /* quickly clear the display */
 599                         charlcd_clear_fast(lcd);
 600                         break;
 601                 case '\n':
 602                         /*
 603                          * flush the remainder of the current line and
 604                          * go to the beginning of the next line
 605                          */
 606                         for (; priv->addr.x < lcd->bwidth; priv->addr.x++)
 607                                 lcd->ops->write_data(lcd, ' ');
 608                         priv->addr.x = 0;
 609                         priv->addr.y = (priv->addr.y + 1) % lcd->height;
 610                         charlcd_gotoxy(lcd);
 611                         break;
 612                 case '\r':
 613                         /* go to the beginning of the same line */
 614                         priv->addr.x = 0;
 615                         charlcd_gotoxy(lcd);
 616                         break;
 617                 case '\t':
 618                         /* print a space instead of the tab */
 619                         charlcd_print(lcd, ' ');
 620                         break;
 621                 default:
 622                         /* simply print this char */
 623                         charlcd_print(lcd, c);
 624                         break;
 625                 }
 626         }
 627
 628         /*
 629          * now we'll see if we're in an escape mode and if the current
 630          * escape sequence can be understood.
 631          */
 632         if (priv->esc_seq.len >= 2) {
 633                 int processed = 0;
 634
 635                 if (!strcmp(priv->esc_seq.buf, "[2J")) {
 636                         /* clear the display */
 637                         charlcd_clear_fast(lcd);
 638                         processed = 1;
 639                 } else if (!strcmp(priv->esc_seq.buf, "[H")) {
 640                         /* cursor to home */
 641                         charlcd_home(lcd);
 642                         processed = 1;
 643                 }
 644                 /* codes starting with ^[[L */
 645                 else if ((priv->esc_seq.len >= 3) &&
 646                          (priv->esc_seq.buf[0] == '[') &&
 647                          (priv->esc_seq.buf[1] == 'L')) {
 648                         processed = handle_lcd_special_code(lcd);
 649                 }
 650
 651                 /* LCD special escape codes */
 652                 /*
 653                  * flush the escape sequence if it's been processed
 654                  * or if it is getting too long.
 655                  */
 656                 if (processed || (priv->esc_seq.len >= LCD_ESCAPE_LEN))
 657                         priv->esc_seq.len = -1;
 658         } /* escape codes */
 659 }
 660
 661 static struct charlcd *the_charlcd;
 662
 663 static ssize_t charlcd_write(struct file *file, const char __user *buf,
 664                              size_t count, loff_t *ppos)
 665 {
 666         const char __user *tmp = buf;
 667         char c;
 668
 669         for (; count-- > 0; (*ppos)++, tmp++) {
 670                 if (!in_interrupt() && (((count + 1) & 0x1f) == 0))
 671                         /*
 672                          * let's be a little nice with other processes
 673                          * that need some CPU
 674                          */
 675                         schedule();
 676
 677                 if (get_user(c, tmp))
 678                         return -EFAULT;
 679
 680                 charlcd_write_char(the_charlcd, c);
 681         }
 682
 683         return tmp - buf;
 684 }
 685
 686 static int charlcd_open(struct inode *inode, struct file *file)
 687 {
 688         struct charlcd_priv *priv = charlcd_to_priv(the_charlcd);
 689         int ret;
 690
 691         ret = -EBUSY;
 692         if (!atomic_dec_and_test(&charlcd_available))
 693                 goto fail;      /* open only once at a time */
 694
 695         ret = -EPERM;
 696         if (file->f_mode & FMODE_READ)  /* device is write-only */
 697                 goto fail;
 698
 699         if (priv->must_clear) {
 700                 charlcd_clear_display(&priv->lcd);
 701                 priv->must_clear = false;
 702         }
 703         return nonseekable_open(inode, file);
 704
 705  fail:
 706         atomic_inc(&charlcd_available);
 707         return ret;
 708 }
 709
 710 static int charlcd_release(struct inode *inode, struct file *file)
 711 {
 712         atomic_inc(&charlcd_available);
 713         return 0;
 714 }
 715
 716 static const struct file_operations charlcd_fops = {
 717         .write   = charlcd_write,
 718         .open    = charlcd_open,
 719         .release = charlcd_release,
 720         .llseek  = no_llseek,
 721 };
 722
 723 static struct miscdevice charlcd_dev = {
 724         .minor  = LCD_MINOR,
 725         .name   = "lcd",
 726         .fops   = &charlcd_fops,
 727 };
 728
 729 static void charlcd_puts(struct charlcd *lcd, const char *s)
 730 {
 731         const char *tmp = s;
 732         int count = strlen(s);
 733
 734         for (; count-- > 0; tmp++) {
 735                 if (!in_interrupt() && (((count + 1) & 0x1f) == 0))
 736                         /*
 737                          * let's be a little nice with other processes
 738                          * that need some CPU
 739                          */
 740                         schedule();
 741
 742                 charlcd_write_char(lcd, *tmp);
 743         }
 744 }
 745
 746 #ifdef CONFIG_PANEL_BOOT_MESSAGE
 747 #define LCD_INIT_TEXT CONFIG_PANEL_BOOT_MESSAGE
 748 #else
 749 #define LCD_INIT_TEXT "Linux-" UTS_RELEASE "\n"
 750 #endif
 751
 752 #ifdef CONFIG_CHARLCD_BL_ON
 753 #define LCD_INIT_BL "\x1b[L+"
 754 #elif defined(CONFIG_CHARLCD_BL_FLASH)
 755 #define LCD_INIT_BL "\x1b[L*"
 756 #else
 757 #define LCD_INIT_BL "\x1b[L-"
 758 #endif
 759
 760 /* initialize the LCD driver */
 761 static int charlcd_init(struct charlcd *lcd)
 762 {
 763         struct charlcd_priv *priv = charlcd_to_priv(lcd);
 764         int ret;
 765
 766         if (lcd->ops->backlight) {
 767                 mutex_init(&priv->bl_tempo_lock);
 768                 INIT_DELAYED_WORK(&priv->bl_work, charlcd_bl_off);
 769         }
 770
 771         /*
 772          * before this line, we must NOT send anything to the display.
 773          * Since charlcd_init_display() needs to write data, we have to
 774          * enable mark the LCD initialized just before.
 775          */
 776         ret = charlcd_init_display(lcd);
 777         if (ret)
 778                 return ret;
 779
 780         /* display a short message */
 781         charlcd_puts(lcd, "\x1b[Lc\x1b[Lb" LCD_INIT_BL LCD_INIT_TEXT);
 782
 783         /* clear the display on the next device opening */
 784         priv->must_clear = true;
 785         charlcd_home(lcd);
 786         return 0;
 787 }
 788
 789 struct charlcd *charlcd_alloc(unsigned int drvdata_size)
 790 {
 791         struct charlcd_priv *priv;
 792         struct charlcd *lcd;
 793
 794         priv = kzalloc(sizeof(*priv) + drvdata_size, GFP_KERNEL);
 795         if (!priv)
 796                 return NULL;
 797
 798         priv->esc_seq.len = -1;
 799
 800         lcd = &priv->lcd;
 801         lcd->ifwidth = 8;
 802         lcd->bwidth = DEFAULT_LCD_BWIDTH;
 803         lcd->hwidth = DEFAULT_LCD_HWIDTH;
 804         lcd->drvdata = priv->drvdata;
 805
 806         return lcd;
 807 }
 808 EXPORT_SYMBOL_GPL(charlcd_alloc);
 809
 810 void charlcd_free(struct charlcd *lcd)
 811 {
 812         kfree(charlcd_to_priv(lcd));
 813 }
 814 EXPORT_SYMBOL_GPL(charlcd_free);
 815
 816 static int panel_notify_sys(struct notifier_block *this, unsigned long code,
 817                             void *unused)
 818 {
 819         struct charlcd *lcd = the_charlcd;
 820
 821         switch (code) {
 822         case SYS_DOWN:
 823                 charlcd_puts(lcd,
 824                              "\x0cReloading\nSystem...\x1b[Lc\x1b[Lb\x1b[L+");
 825                 break;
 826         case SYS_HALT:
 827                 charlcd_puts(lcd, "\x0cSystem Halted.\x1b[Lc\x1b[Lb\x1b[L+");
 828                 break;
 829         case SYS_POWER_OFF:
 830                 charlcd_puts(lcd, "\x0cPower off.\x1b[Lc\x1b[Lb\x1b[L+");
 831                 break;
 832         default:
 833                 break;
 834         }
 835         return NOTIFY_DONE;
 836 }
 837
 838 static struct notifier_block panel_notifier = {
 839         panel_notify_sys,
 840         NULL,
 841         0
 842 };
 843
 844 int charlcd_register(struct charlcd *lcd)
 845 {
 846         int ret;
 847
 848         ret = charlcd_init(lcd);
 849         if (ret)
 850                 return ret;
 851
 852         ret = misc_register(&charlcd_dev);
 853         if (ret)
 854                 return ret;
 855
 856         the_charlcd = lcd;
 857         register_reboot_notifier(&panel_notifier);
 858         return 0;
 859 }
 860 EXPORT_SYMBOL_GPL(charlcd_register);
 861
 862 int charlcd_unregister(struct charlcd *lcd)
 863 {
 864         struct charlcd_priv *priv = charlcd_to_priv(lcd);
 865
 866         unregister_reboot_notifier(&panel_notifier);
 867         charlcd_puts(lcd, "\x0cLCD driver unloaded.\x1b[Lc\x1b[Lb\x1b[L-");
 868         misc_deregister(&charlcd_dev);
 869         the_charlcd = NULL;
 870         if (lcd->ops->backlight) {
 871                 cancel_delayed_work_sync(&priv->bl_work);
 872                 priv->lcd.ops->backlight(&priv->lcd, 0);
 873         }
 874
 875         return 0;
 876 }
 877 EXPORT_SYMBOL_GPL(charlcd_unregister);
 878
 879 MODULE_LICENSE("GPL");