drivers/auxdisplay/hd44780_common.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 #include <linux/module.h>
   3 #include <linux/sched.h>
   4 #include <linux/slab.h>
   5
   6 #include "charlcd.h"
   7 #include "hd44780_common.h"
   8
   9 /* LCD commands */
  10 #define LCD_CMD_DISPLAY_CLEAR   0x01    /* Clear entire display */
  11
  12 #define LCD_CMD_ENTRY_MODE      0x04    /* Set entry mode */
  13 #define LCD_CMD_CURSOR_INC      0x02    /* Increment cursor */
  14
  15 #define LCD_CMD_DISPLAY_CTRL    0x08    /* Display control */
  16 #define LCD_CMD_DISPLAY_ON      0x04    /* Set display on */
  17 #define LCD_CMD_CURSOR_ON       0x02    /* Set cursor on */
  18 #define LCD_CMD_BLINK_ON        0x01    /* Set blink on */
  19
  20 #define LCD_CMD_SHIFT           0x10    /* Shift cursor/display */
  21 #define LCD_CMD_DISPLAY_SHIFT   0x08    /* Shift display instead of cursor */
  22 #define LCD_CMD_SHIFT_RIGHT     0x04    /* Shift display/cursor to the right */
  23
  24 #define LCD_CMD_FUNCTION_SET    0x20    /* Set function */
  25 #define LCD_CMD_DATA_LEN_8BITS  0x10    /* Set data length to 8 bits */
  26 #define LCD_CMD_TWO_LINES       0x08    /* Set to two display lines */
  27 #define LCD_CMD_FONT_5X10_DOTS  0x04    /* Set char font to 5x10 dots */
  28
  29 #define LCD_CMD_SET_CGRAM_ADDR  0x40    /* Set char generator RAM address */
  30
  31 #define LCD_CMD_SET_DDRAM_ADDR  0x80    /* Set display data RAM address */
  32
  33 /* sleeps that many milliseconds with a reschedule */
  34 static void long_sleep(int ms)
  35 {
  36         schedule_timeout_interruptible(msecs_to_jiffies(ms));
  37 }
  38
  39 int hd44780_common_print(struct charlcd *lcd, int c)
  40 {
  41         struct hd44780_common *hdc = lcd->drvdata;
  42
  43         if (lcd->addr.x < hdc->bwidth) {
  44                 hdc->write_data(hdc, c);
  45                 return 0;
  46         }
  47
  48         return 1;
  49 }
  50 EXPORT_SYMBOL_GPL(hd44780_common_print);
  51
  52 int hd44780_common_gotoxy(struct charlcd *lcd, unsigned int x, unsigned int y)
  53 {
  54         struct hd44780_common *hdc = lcd->drvdata;
  55         unsigned int addr;
  56
  57         /*
  58          * we force the cursor to stay at the end of the
  59          * line if it wants to go farther
  60          */
  61         addr = x < hdc->bwidth ? x & (hdc->hwidth - 1) : hdc->bwidth - 1;
  62         if (y & 1)
  63                 addr += hdc->hwidth;
  64         if (y & 2)
  65                 addr += hdc->bwidth;
  66         hdc->write_cmd(hdc, LCD_CMD_SET_DDRAM_ADDR | addr);
  67         return 0;
  68 }
  69 EXPORT_SYMBOL_GPL(hd44780_common_gotoxy);
  70
  71 int hd44780_common_home(struct charlcd *lcd)
  72 {
  73         return hd44780_common_gotoxy(lcd, 0, 0);
  74 }
  75 EXPORT_SYMBOL_GPL(hd44780_common_home);
  76
  77 /* clears the display and resets X/Y */
  78 int hd44780_common_clear_display(struct charlcd *lcd)
  79 {
  80         struct hd44780_common *hdc = lcd->drvdata;
  81
  82         hdc->write_cmd(hdc, LCD_CMD_DISPLAY_CLEAR);
  83         /* datasheet says to wait 1,64 milliseconds */
  84         long_sleep(2);
  85
  86         /*
  87          * The Hitachi HD44780 controller (and compatible ones) reset the DDRAM
  88          * address when executing the DISPLAY_CLEAR command, thus the
  89          * following call is not required. However, other controllers do not
  90          * (e.g. NewHaven NHD-0220DZW-AG5), thus move the cursor to home
  91          * unconditionally to support both.
  92          */
  93         return hd44780_common_home(lcd);
  94 }
  95 EXPORT_SYMBOL_GPL(hd44780_common_clear_display);
  96
  97 int hd44780_common_init_display(struct charlcd *lcd)
  98 {
  99         struct hd44780_common *hdc = lcd->drvdata;
 100
 101         void (*write_cmd_raw)(struct hd44780_common *hdc, int cmd);
 102         u8 init;
 103
 104         if (hdc->ifwidth != 4 && hdc->ifwidth != 8)
 105                 return -EINVAL;
 106
 107         hdc->hd44780_common_flags = ((lcd->height > 1) ? LCD_FLAG_N : 0) |
 108                 LCD_FLAG_D | LCD_FLAG_C | LCD_FLAG_B;
 109
 110         long_sleep(20);         /* wait 20 ms after power-up for the paranoid */
 111
 112         /*
 113          * 8-bit mode, 1 line, small fonts; let's do it 3 times, to make sure
 114          * the LCD is in 8-bit mode afterwards
 115          */
 116         init = LCD_CMD_FUNCTION_SET | LCD_CMD_DATA_LEN_8BITS;
 117         if (hdc->ifwidth == 4) {
 118                 init >>= 4;
 119                 write_cmd_raw = hdc->write_cmd_raw4;
 120         } else {
 121                 write_cmd_raw = hdc->write_cmd;
 122         }
 123         write_cmd_raw(hdc, init);
 124         long_sleep(10);
 125         write_cmd_raw(hdc, init);
 126         long_sleep(10);
 127         write_cmd_raw(hdc, init);
 128         long_sleep(10);
 129
 130         if (hdc->ifwidth == 4) {
 131                 /* Switch to 4-bit mode, 1 line, small fonts */
 132                 hdc->write_cmd_raw4(hdc, LCD_CMD_FUNCTION_SET >> 4);
 133                 long_sleep(10);
 134         }
 135
 136         /* set font height and lines number */
 137         hdc->write_cmd(hdc,
 138                 LCD_CMD_FUNCTION_SET |
 139                 ((hdc->ifwidth == 8) ? LCD_CMD_DATA_LEN_8BITS : 0) |
 140                 ((hdc->hd44780_common_flags & LCD_FLAG_F) ?
 141                         LCD_CMD_FONT_5X10_DOTS : 0) |
 142                 ((hdc->hd44780_common_flags & LCD_FLAG_N) ?
 143                         LCD_CMD_TWO_LINES : 0));
 144         long_sleep(10);
 145
 146         /* display off, cursor off, blink off */
 147         hdc->write_cmd(hdc, LCD_CMD_DISPLAY_CTRL);
 148         long_sleep(10);
 149
 150         hdc->write_cmd(hdc,
 151                 LCD_CMD_DISPLAY_CTRL |  /* set display mode */
 152                 ((hdc->hd44780_common_flags & LCD_FLAG_D) ?
 153                         LCD_CMD_DISPLAY_ON : 0) |
 154                 ((hdc->hd44780_common_flags & LCD_FLAG_C) ?
 155                         LCD_CMD_CURSOR_ON : 0) |
 156                 ((hdc->hd44780_common_flags & LCD_FLAG_B) ?
 157                         LCD_CMD_BLINK_ON : 0));
 158
 159         charlcd_backlight(lcd,
 160                         (hdc->hd44780_common_flags & LCD_FLAG_L) ? 1 : 0);
 161
 162         long_sleep(10);
 163
 164         /* entry mode set : increment, cursor shifting */
 165         hdc->write_cmd(hdc, LCD_CMD_ENTRY_MODE | LCD_CMD_CURSOR_INC);
 166
 167         hd44780_common_clear_display(lcd);
 168         return 0;
 169 }
 170 EXPORT_SYMBOL_GPL(hd44780_common_init_display);
 171
 172 int hd44780_common_shift_cursor(struct charlcd *lcd, enum charlcd_shift_dir dir)
 173 {
 174         struct hd44780_common *hdc = lcd->drvdata;
 175
 176         if (dir == CHARLCD_SHIFT_LEFT) {
 177                 /* back one char if not at end of line */
 178                 if (lcd->addr.x < hdc->bwidth)
 179                         hdc->write_cmd(hdc, LCD_CMD_SHIFT);
 180         } else if (dir == CHARLCD_SHIFT_RIGHT) {
 181                 /* allow the cursor to pass the end of the line */
 182                 if (lcd->addr.x < (hdc->bwidth - 1))
 183                         hdc->write_cmd(hdc,
 184                                         LCD_CMD_SHIFT | LCD_CMD_SHIFT_RIGHT);
 185         }
 186
 187         return 0;
 188 }
 189 EXPORT_SYMBOL_GPL(hd44780_common_shift_cursor);
 190
 191 int hd44780_common_shift_display(struct charlcd *lcd,
 192                 enum charlcd_shift_dir dir)
 193 {
 194         struct hd44780_common *hdc = lcd->drvdata;
 195
 196         if (dir == CHARLCD_SHIFT_LEFT)
 197                 hdc->write_cmd(hdc, LCD_CMD_SHIFT | LCD_CMD_DISPLAY_SHIFT);
 198         else if (dir == CHARLCD_SHIFT_RIGHT)
 199                 hdc->write_cmd(hdc, LCD_CMD_SHIFT | LCD_CMD_DISPLAY_SHIFT |
 200                         LCD_CMD_SHIFT_RIGHT);
 201
 202         return 0;
 203 }
 204 EXPORT_SYMBOL_GPL(hd44780_common_shift_display);
 205
 206 static void hd44780_common_set_mode(struct hd44780_common *hdc)
 207 {
 208         hdc->write_cmd(hdc,
 209                 LCD_CMD_DISPLAY_CTRL |
 210                 ((hdc->hd44780_common_flags & LCD_FLAG_D) ?
 211                         LCD_CMD_DISPLAY_ON : 0) |
 212                 ((hdc->hd44780_common_flags & LCD_FLAG_C) ?
 213                         LCD_CMD_CURSOR_ON : 0) |
 214                 ((hdc->hd44780_common_flags & LCD_FLAG_B) ?
 215                         LCD_CMD_BLINK_ON : 0));
 216 }
 217
 218 int hd44780_common_display(struct charlcd *lcd, enum charlcd_onoff on)
 219 {
 220         struct hd44780_common *hdc = lcd->drvdata;
 221
 222         if (on == CHARLCD_ON)
 223                 hdc->hd44780_common_flags |= LCD_FLAG_D;
 224         else
 225                 hdc->hd44780_common_flags &= ~LCD_FLAG_D;
 226
 227         hd44780_common_set_mode(hdc);
 228         return 0;
 229 }
 230 EXPORT_SYMBOL_GPL(hd44780_common_display);
 231
 232 int hd44780_common_cursor(struct charlcd *lcd, enum charlcd_onoff on)
 233 {
 234         struct hd44780_common *hdc = lcd->drvdata;
 235
 236         if (on == CHARLCD_ON)
 237                 hdc->hd44780_common_flags |= LCD_FLAG_C;
 238         else
 239                 hdc->hd44780_common_flags &= ~LCD_FLAG_C;
 240
 241         hd44780_common_set_mode(hdc);
 242         return 0;
 243 }
 244 EXPORT_SYMBOL_GPL(hd44780_common_cursor);
 245
 246 int hd44780_common_blink(struct charlcd *lcd, enum charlcd_onoff on)
 247 {
 248         struct hd44780_common *hdc = lcd->drvdata;
 249
 250         if (on == CHARLCD_ON)
 251                 hdc->hd44780_common_flags |= LCD_FLAG_B;
 252         else
 253                 hdc->hd44780_common_flags &= ~LCD_FLAG_B;
 254
 255         hd44780_common_set_mode(hdc);
 256         return 0;
 257 }
 258 EXPORT_SYMBOL_GPL(hd44780_common_blink);
 259
 260 static void hd44780_common_set_function(struct hd44780_common *hdc)
 261 {
 262         hdc->write_cmd(hdc,
 263                 LCD_CMD_FUNCTION_SET |
 264                 ((hdc->ifwidth == 8) ? LCD_CMD_DATA_LEN_8BITS : 0) |
 265                 ((hdc->hd44780_common_flags & LCD_FLAG_F) ?
 266                         LCD_CMD_FONT_5X10_DOTS : 0) |
 267                 ((hdc->hd44780_common_flags & LCD_FLAG_N) ?
 268                         LCD_CMD_TWO_LINES : 0));
 269 }
 270
 271 int hd44780_common_fontsize(struct charlcd *lcd, enum charlcd_fontsize size)
 272 {
 273         struct hd44780_common *hdc = lcd->drvdata;
 274
 275         if (size == CHARLCD_FONTSIZE_LARGE)
 276                 hdc->hd44780_common_flags |= LCD_FLAG_F;
 277         else
 278                 hdc->hd44780_common_flags &= ~LCD_FLAG_F;
 279
 280         hd44780_common_set_function(hdc);
 281         return 0;
 282 }
 283 EXPORT_SYMBOL_GPL(hd44780_common_fontsize);
 284
 285 int hd44780_common_lines(struct charlcd *lcd, enum charlcd_lines lines)
 286 {
 287         struct hd44780_common *hdc = lcd->drvdata;
 288
 289         if (lines == CHARLCD_LINES_2)
 290                 hdc->hd44780_common_flags |= LCD_FLAG_N;
 291         else
 292                 hdc->hd44780_common_flags &= ~LCD_FLAG_N;
 293
 294         hd44780_common_set_function(hdc);
 295         return 0;
 296 }
 297 EXPORT_SYMBOL_GPL(hd44780_common_lines);
 298
 299 int hd44780_common_redefine_char(struct charlcd *lcd, char *esc)
 300 {
 301         /* Generator : LGcxxxxx...xx; must have <c> between '0'
 302          * and '7', representing the numerical ASCII code of the
 303          * redefined character, and <xx...xx> a sequence of 16
 304          * hex digits representing 8 bytes for each character.
 305          * Most LCDs will only use 5 lower bits of the 7 first
 306          * bytes.
 307          */
 308
 309         struct hd44780_common *hdc = lcd->drvdata;
 310         unsigned char cgbytes[8];
 311         unsigned char cgaddr;
 312         int cgoffset;
 313         int shift;
 314         char value;
 315         int addr;
 316
 317         if (!strchr(esc, ';'))
 318                 return 0;
 319
 320         esc++;
 321
 322         cgaddr = *(esc++) - '0';
 323         if (cgaddr > 7)
 324                 return 1;
 325
 326         cgoffset = 0;
 327         shift = 0;
 328         value = 0;
 329         while (*esc && cgoffset < 8) {
 330                 int half;
 331
 332                 shift ^= 4;
 333                 half = hex_to_bin(*esc++);
 334                 if (half < 0)
 335                         continue;
 336
 337                 value |= half << shift;
 338                 if (shift == 0) {
 339                         cgbytes[cgoffset++] = value;
 340                         value = 0;
 341                 }
 342         }
 343
 344         hdc->write_cmd(hdc, LCD_CMD_SET_CGRAM_ADDR | (cgaddr * 8));
 345         for (addr = 0; addr < cgoffset; addr++)
 346                 hdc->write_data(hdc, cgbytes[addr]);
 347
 348         /* ensures that we stop writing to CGRAM */
 349         lcd->ops->gotoxy(lcd, lcd->addr.x, lcd->addr.y);
 350         return 1;
 351 }
 352 EXPORT_SYMBOL_GPL(hd44780_common_redefine_char);
 353
 354 struct hd44780_common *hd44780_common_alloc(void)
 355 {
 356         struct hd44780_common *hd;
 357
 358         hd = kzalloc(sizeof(*hd), GFP_KERNEL);
 359         if (!hd)
 360                 return NULL;
 361
 362         hd->ifwidth = 8;
 363         hd->bwidth = DEFAULT_LCD_BWIDTH;
 364         hd->hwidth = DEFAULT_LCD_HWIDTH;
 365         return hd;
 366 }
 367 EXPORT_SYMBOL_GPL(hd44780_common_alloc);
 368
 369 MODULE_DESCRIPTION("Common functions for HD44780 (and compatibles) LCD displays");
 370 MODULE_LICENSE("GPL");