1 // SPDX-License-Identifier: GPL-2.0-or-later
2 #include <linux/module.h>
3 #include <linux/sched.h>
4 #include <linux/slab.h>
7 #include "hd44780_common.h"
10 #define LCD_CMD_DISPLAY_CLEAR 0x01 /* Clear entire display */
12 #define LCD_CMD_ENTRY_MODE 0x04 /* Set entry mode */
13 #define LCD_CMD_CURSOR_INC 0x02 /* Increment cursor */
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 */
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 */
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 */
29 #define LCD_CMD_SET_CGRAM_ADDR 0x40 /* Set char generator RAM address */
31 #define LCD_CMD_SET_DDRAM_ADDR 0x80 /* Set display data RAM address */
33 /* sleeps that many milliseconds with a reschedule */
34 static void long_sleep(int ms)
36 schedule_timeout_interruptible(msecs_to_jiffies(ms));
39 int hd44780_common_print(struct charlcd *lcd, int c)
41 struct hd44780_common *hdc = lcd->drvdata;
43 if (lcd->addr.x < hdc->bwidth) {
44 hdc->write_data(hdc, c);
50 EXPORT_SYMBOL_GPL(hd44780_common_print);
52 int hd44780_common_gotoxy(struct charlcd *lcd, unsigned int x, unsigned int y)
54 struct hd44780_common *hdc = lcd->drvdata;
58 * we force the cursor to stay at the end of the
59 * line if it wants to go farther
61 addr = x < hdc->bwidth ? x & (hdc->hwidth - 1) : hdc->bwidth - 1;
66 hdc->write_cmd(hdc, LCD_CMD_SET_DDRAM_ADDR | addr);
69 EXPORT_SYMBOL_GPL(hd44780_common_gotoxy);
71 int hd44780_common_home(struct charlcd *lcd)
73 return hd44780_common_gotoxy(lcd, 0, 0);
75 EXPORT_SYMBOL_GPL(hd44780_common_home);
77 /* clears the display and resets X/Y */
78 int hd44780_common_clear_display(struct charlcd *lcd)
80 struct hd44780_common *hdc = lcd->drvdata;
82 hdc->write_cmd(hdc, LCD_CMD_DISPLAY_CLEAR);
83 /* datasheet says to wait 1,64 milliseconds */
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.
93 return hd44780_common_home(lcd);
95 EXPORT_SYMBOL_GPL(hd44780_common_clear_display);
97 int hd44780_common_init_display(struct charlcd *lcd)
99 struct hd44780_common *hdc = lcd->drvdata;
101 void (*write_cmd_raw)(struct hd44780_common *hdc, int cmd);
104 if (hdc->ifwidth != 4 && hdc->ifwidth != 8)
107 hdc->hd44780_common_flags = ((lcd->height > 1) ? LCD_FLAG_N : 0) |
108 LCD_FLAG_D | LCD_FLAG_C | LCD_FLAG_B;
110 long_sleep(20); /* wait 20 ms after power-up for the paranoid */
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
116 init = LCD_CMD_FUNCTION_SET | LCD_CMD_DATA_LEN_8BITS;
117 if (hdc->ifwidth == 4) {
119 write_cmd_raw = hdc->write_cmd_raw4;
121 write_cmd_raw = hdc->write_cmd;
123 write_cmd_raw(hdc, init);
125 write_cmd_raw(hdc, init);
127 write_cmd_raw(hdc, init);
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);
136 /* set font height and lines number */
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));
146 /* display off, cursor off, blink off */
147 hdc->write_cmd(hdc, LCD_CMD_DISPLAY_CTRL);
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));
159 charlcd_backlight(lcd,
160 (hdc->hd44780_common_flags & LCD_FLAG_L) ? 1 : 0);
164 /* entry mode set : increment, cursor shifting */
165 hdc->write_cmd(hdc, LCD_CMD_ENTRY_MODE | LCD_CMD_CURSOR_INC);
167 hd44780_common_clear_display(lcd);
170 EXPORT_SYMBOL_GPL(hd44780_common_init_display);
172 int hd44780_common_shift_cursor(struct charlcd *lcd, enum charlcd_shift_dir dir)
174 struct hd44780_common *hdc = lcd->drvdata;
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))
184 LCD_CMD_SHIFT | LCD_CMD_SHIFT_RIGHT);
189 EXPORT_SYMBOL_GPL(hd44780_common_shift_cursor);
191 int hd44780_common_shift_display(struct charlcd *lcd,
192 enum charlcd_shift_dir dir)
194 struct hd44780_common *hdc = lcd->drvdata;
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);
204 EXPORT_SYMBOL_GPL(hd44780_common_shift_display);
206 static void hd44780_common_set_mode(struct hd44780_common *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));
218 int hd44780_common_display(struct charlcd *lcd, enum charlcd_onoff on)
220 struct hd44780_common *hdc = lcd->drvdata;
222 if (on == CHARLCD_ON)
223 hdc->hd44780_common_flags |= LCD_FLAG_D;
225 hdc->hd44780_common_flags &= ~LCD_FLAG_D;
227 hd44780_common_set_mode(hdc);
230 EXPORT_SYMBOL_GPL(hd44780_common_display);
232 int hd44780_common_cursor(struct charlcd *lcd, enum charlcd_onoff on)
234 struct hd44780_common *hdc = lcd->drvdata;
236 if (on == CHARLCD_ON)
237 hdc->hd44780_common_flags |= LCD_FLAG_C;
239 hdc->hd44780_common_flags &= ~LCD_FLAG_C;
241 hd44780_common_set_mode(hdc);
244 EXPORT_SYMBOL_GPL(hd44780_common_cursor);
246 int hd44780_common_blink(struct charlcd *lcd, enum charlcd_onoff on)
248 struct hd44780_common *hdc = lcd->drvdata;
250 if (on == CHARLCD_ON)
251 hdc->hd44780_common_flags |= LCD_FLAG_B;
253 hdc->hd44780_common_flags &= ~LCD_FLAG_B;
255 hd44780_common_set_mode(hdc);
258 EXPORT_SYMBOL_GPL(hd44780_common_blink);
260 static void hd44780_common_set_function(struct hd44780_common *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));
271 int hd44780_common_fontsize(struct charlcd *lcd, enum charlcd_fontsize size)
273 struct hd44780_common *hdc = lcd->drvdata;
275 if (size == CHARLCD_FONTSIZE_LARGE)
276 hdc->hd44780_common_flags |= LCD_FLAG_F;
278 hdc->hd44780_common_flags &= ~LCD_FLAG_F;
280 hd44780_common_set_function(hdc);
283 EXPORT_SYMBOL_GPL(hd44780_common_fontsize);
285 int hd44780_common_lines(struct charlcd *lcd, enum charlcd_lines lines)
287 struct hd44780_common *hdc = lcd->drvdata;
289 if (lines == CHARLCD_LINES_2)
290 hdc->hd44780_common_flags |= LCD_FLAG_N;
292 hdc->hd44780_common_flags &= ~LCD_FLAG_N;
294 hd44780_common_set_function(hdc);
297 EXPORT_SYMBOL_GPL(hd44780_common_lines);
299 int hd44780_common_redefine_char(struct charlcd *lcd, char *esc)
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
309 struct hd44780_common *hdc = lcd->drvdata;
310 unsigned char cgbytes[8];
311 unsigned char cgaddr;
317 if (!strchr(esc, ';'))
322 cgaddr = *(esc++) - '0';
329 while (*esc && cgoffset < 8) {
333 half = hex_to_bin(*esc++);
337 value |= half << shift;
339 cgbytes[cgoffset++] = value;
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]);
348 /* ensures that we stop writing to CGRAM */
349 lcd->ops->gotoxy(lcd, lcd->addr.x, lcd->addr.y);
352 EXPORT_SYMBOL_GPL(hd44780_common_redefine_char);
354 struct hd44780_common *hd44780_common_alloc(void)
356 struct hd44780_common *hd;
358 hd = kzalloc(sizeof(*hd), GFP_KERNEL);
363 hd->bwidth = DEFAULT_LCD_BWIDTH;
364 hd->hwidth = DEFAULT_LCD_HWIDTH;
367 EXPORT_SYMBOL_GPL(hd44780_common_alloc);
369 MODULE_DESCRIPTION("Common functions for HD44780 (and compatibles) LCD displays");
370 MODULE_LICENSE("GPL");