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_LICENSE("GPL");
370