1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Console driver for LCD2S 4x20 character displays connected through i2c.
4 * The display also has a SPI interface, but the driver does not support
5 * this yet.
6 *
7 * This is a driver allowing you to use a LCD2S 4x20 from Modtronix
8 * engineering as auxdisplay character device.
9 *
10 * (C) 2019 by Lemonage Software GmbH
11 * Author: Lars Pöschel <poeschel@lemonage.de>
12 * All rights reserved.
13 */
14 #include <linux/kernel.h>
15 #include <linux/mod_devicetable.h>
16 #include <linux/module.h>
17 #include <linux/property.h>
18 #include <linux/slab.h>
19 #include <linux/i2c.h>
20 #include <linux/delay.h>
21
22 #include "charlcd.h"
23
24 #define LCD2S_CMD_CUR_MOVES_FWD 0x09
25 #define LCD2S_CMD_CUR_BLINK_OFF 0x10
26 #define LCD2S_CMD_CUR_UL_OFF 0x11
27 #define LCD2S_CMD_DISPLAY_OFF 0x12
28 #define LCD2S_CMD_CUR_BLINK_ON 0x18
29 #define LCD2S_CMD_CUR_UL_ON 0x19
30 #define LCD2S_CMD_DISPLAY_ON 0x1a
31 #define LCD2S_CMD_BACKLIGHT_OFF 0x20
32 #define LCD2S_CMD_BACKLIGHT_ON 0x28
33 #define LCD2S_CMD_WRITE 0x80
34 #define LCD2S_CMD_MOV_CUR_RIGHT 0x83
35 #define LCD2S_CMD_MOV_CUR_LEFT 0x84
36 #define LCD2S_CMD_SHIFT_RIGHT 0x85
37 #define LCD2S_CMD_SHIFT_LEFT 0x86
38 #define LCD2S_CMD_SHIFT_UP 0x87
39 #define LCD2S_CMD_SHIFT_DOWN 0x88
40 #define LCD2S_CMD_CUR_ADDR 0x89
41 #define LCD2S_CMD_CUR_POS 0x8a
42 #define LCD2S_CMD_CUR_RESET 0x8b
43 #define LCD2S_CMD_CLEAR 0x8c
44 #define LCD2S_CMD_DEF_CUSTOM_CHAR 0x92
45 #define LCD2S_CMD_READ_STATUS 0xd0
46
47 #define LCD2S_CHARACTER_SIZE 8
48
49 #define LCD2S_STATUS_BUF_MASK 0x7f
50
51 struct lcd2s_data {
52 struct i2c_client *i2c;
53 struct charlcd *charlcd;
54 };
55
lcd2s_wait_buf_free(const struct i2c_client * client,int count)56 static s32 lcd2s_wait_buf_free(const struct i2c_client *client, int count)
57 {
58 s32 status;
59
60 status = i2c_smbus_read_byte_data(client, LCD2S_CMD_READ_STATUS);
61 if (status < 0)
62 return status;
63
64 while ((status & LCD2S_STATUS_BUF_MASK) < count) {
65 mdelay(1);
66 status = i2c_smbus_read_byte_data(client,
67 LCD2S_CMD_READ_STATUS);
68 if (status < 0)
69 return status;
70 }
71 return 0;
72 }
73
lcd2s_i2c_master_send(const struct i2c_client * client,const char * buf,int count)74 static int lcd2s_i2c_master_send(const struct i2c_client *client,
75 const char *buf, int count)
76 {
77 s32 status;
78
79 status = lcd2s_wait_buf_free(client, count);
80 if (status < 0)
81 return status;
82
83 return i2c_master_send(client, buf, count);
84 }
85
lcd2s_i2c_smbus_write_byte(const struct i2c_client * client,u8 value)86 static int lcd2s_i2c_smbus_write_byte(const struct i2c_client *client, u8 value)
87 {
88 s32 status;
89
90 status = lcd2s_wait_buf_free(client, 1);
91 if (status < 0)
92 return status;
93
94 return i2c_smbus_write_byte(client, value);
95 }
96
lcd2s_print(struct charlcd * lcd,int c)97 static int lcd2s_print(struct charlcd *lcd, int c)
98 {
99 struct lcd2s_data *lcd2s = lcd->drvdata;
100 u8 buf[2] = { LCD2S_CMD_WRITE, c };
101
102 lcd2s_i2c_master_send(lcd2s->i2c, buf, sizeof(buf));
103 return 0;
104 }
105
lcd2s_gotoxy(struct charlcd * lcd,unsigned int x,unsigned int y)106 static int lcd2s_gotoxy(struct charlcd *lcd, unsigned int x, unsigned int y)
107 {
108 struct lcd2s_data *lcd2s = lcd->drvdata;
109 u8 buf[3] = { LCD2S_CMD_CUR_POS, y + 1, x + 1 };
110
111 lcd2s_i2c_master_send(lcd2s->i2c, buf, sizeof(buf));
112
113 return 0;
114 }
115
lcd2s_home(struct charlcd * lcd)116 static int lcd2s_home(struct charlcd *lcd)
117 {
118 struct lcd2s_data *lcd2s = lcd->drvdata;
119
120 lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_CUR_RESET);
121 return 0;
122 }
123
lcd2s_init_display(struct charlcd * lcd)124 static int lcd2s_init_display(struct charlcd *lcd)
125 {
126 struct lcd2s_data *lcd2s = lcd->drvdata;
127
128 /* turn everything off, but display on */
129 lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_DISPLAY_ON);
130 lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_BACKLIGHT_OFF);
131 lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_CUR_MOVES_FWD);
132 lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_CUR_BLINK_OFF);
133 lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_CUR_UL_OFF);
134 lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_CLEAR);
135
136 return 0;
137 }
138
lcd2s_shift_cursor(struct charlcd * lcd,enum charlcd_shift_dir dir)139 static int lcd2s_shift_cursor(struct charlcd *lcd, enum charlcd_shift_dir dir)
140 {
141 struct lcd2s_data *lcd2s = lcd->drvdata;
142
143 if (dir == CHARLCD_SHIFT_LEFT)
144 lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_MOV_CUR_LEFT);
145 else
146 lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_MOV_CUR_RIGHT);
147
148 return 0;
149 }
150
lcd2s_shift_display(struct charlcd * lcd,enum charlcd_shift_dir dir)151 static int lcd2s_shift_display(struct charlcd *lcd, enum charlcd_shift_dir dir)
152 {
153 struct lcd2s_data *lcd2s = lcd->drvdata;
154
155 if (dir == CHARLCD_SHIFT_LEFT)
156 lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_SHIFT_LEFT);
157 else
158 lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_SHIFT_RIGHT);
159
160 return 0;
161 }
162
lcd2s_backlight(struct charlcd * lcd,enum charlcd_onoff on)163 static void lcd2s_backlight(struct charlcd *lcd, enum charlcd_onoff on)
164 {
165 struct lcd2s_data *lcd2s = lcd->drvdata;
166
167 if (on)
168 lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_BACKLIGHT_ON);
169 else
170 lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_BACKLIGHT_OFF);
171 }
172
lcd2s_display(struct charlcd * lcd,enum charlcd_onoff on)173 static int lcd2s_display(struct charlcd *lcd, enum charlcd_onoff on)
174 {
175 struct lcd2s_data *lcd2s = lcd->drvdata;
176
177 if (on)
178 lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_DISPLAY_ON);
179 else
180 lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_DISPLAY_OFF);
181
182 return 0;
183 }
184
lcd2s_cursor(struct charlcd * lcd,enum charlcd_onoff on)185 static int lcd2s_cursor(struct charlcd *lcd, enum charlcd_onoff on)
186 {
187 struct lcd2s_data *lcd2s = lcd->drvdata;
188
189 if (on)
190 lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_CUR_UL_ON);
191 else
192 lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_CUR_UL_OFF);
193
194 return 0;
195 }
196
lcd2s_blink(struct charlcd * lcd,enum charlcd_onoff on)197 static int lcd2s_blink(struct charlcd *lcd, enum charlcd_onoff on)
198 {
199 struct lcd2s_data *lcd2s = lcd->drvdata;
200
201 if (on)
202 lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_CUR_BLINK_ON);
203 else
204 lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_CUR_BLINK_OFF);
205
206 return 0;
207 }
208
lcd2s_fontsize(struct charlcd * lcd,enum charlcd_fontsize size)209 static int lcd2s_fontsize(struct charlcd *lcd, enum charlcd_fontsize size)
210 {
211 return 0;
212 }
213
lcd2s_lines(struct charlcd * lcd,enum charlcd_lines lines)214 static int lcd2s_lines(struct charlcd *lcd, enum charlcd_lines lines)
215 {
216 return 0;
217 }
218
219 /*
220 * Generator: LGcxxxxx...xx; must have <c> between '0' and '7',
221 * representing the numerical ASCII code of the redefined character,
222 * and <xx...xx> a sequence of 16 hex digits representing 8 bytes
223 * for each character. Most LCDs will only use 5 lower bits of
224 * the 7 first bytes.
225 */
lcd2s_redefine_char(struct charlcd * lcd,char * esc)226 static int lcd2s_redefine_char(struct charlcd *lcd, char *esc)
227 {
228 struct lcd2s_data *lcd2s = lcd->drvdata;
229 u8 buf[LCD2S_CHARACTER_SIZE + 2] = { LCD2S_CMD_DEF_CUSTOM_CHAR };
230 u8 value;
231 int shift, i;
232
233 if (!strchr(esc, ';'))
234 return 0;
235
236 esc++;
237
238 buf[1] = *(esc++) - '0';
239 if (buf[1] > 7)
240 return 1;
241
242 i = 2;
243 shift = 0;
244 value = 0;
245 while (*esc && i < LCD2S_CHARACTER_SIZE + 2) {
246 int half;
247
248 shift ^= 4;
249 half = hex_to_bin(*esc++);
250 if (half < 0)
251 continue;
252
253 value |= half << shift;
254 if (shift == 0) {
255 buf[i++] = value;
256 value = 0;
257 }
258 }
259
260 lcd2s_i2c_master_send(lcd2s->i2c, buf, sizeof(buf));
261 return 1;
262 }
263
lcd2s_clear_display(struct charlcd * lcd)264 static int lcd2s_clear_display(struct charlcd *lcd)
265 {
266 struct lcd2s_data *lcd2s = lcd->drvdata;
267
268 /* This implicitly sets cursor to first row and column */
269 lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_CLEAR);
270 return 0;
271 }
272
273 static const struct charlcd_ops lcd2s_ops = {
274 .print = lcd2s_print,
275 .backlight = lcd2s_backlight,
276 .gotoxy = lcd2s_gotoxy,
277 .home = lcd2s_home,
278 .clear_display = lcd2s_clear_display,
279 .init_display = lcd2s_init_display,
280 .shift_cursor = lcd2s_shift_cursor,
281 .shift_display = lcd2s_shift_display,
282 .display = lcd2s_display,
283 .cursor = lcd2s_cursor,
284 .blink = lcd2s_blink,
285 .fontsize = lcd2s_fontsize,
286 .lines = lcd2s_lines,
287 .redefine_char = lcd2s_redefine_char,
288 };
289
lcd2s_i2c_probe(struct i2c_client * i2c)290 static int lcd2s_i2c_probe(struct i2c_client *i2c)
291 {
292 struct charlcd *lcd;
293 struct lcd2s_data *lcd2s;
294 int err;
295
296 if (!i2c_check_functionality(i2c->adapter,
297 I2C_FUNC_SMBUS_WRITE_BYTE_DATA |
298 I2C_FUNC_SMBUS_WRITE_BLOCK_DATA))
299 return -EIO;
300
301 lcd2s = devm_kzalloc(&i2c->dev, sizeof(*lcd2s), GFP_KERNEL);
302 if (!lcd2s)
303 return -ENOMEM;
304
305 /* Test, if the display is responding */
306 err = lcd2s_i2c_smbus_write_byte(i2c, LCD2S_CMD_DISPLAY_OFF);
307 if (err < 0)
308 return err;
309
310 lcd = charlcd_alloc();
311 if (!lcd)
312 return -ENOMEM;
313
314 lcd->drvdata = lcd2s;
315 lcd2s->i2c = i2c;
316 lcd2s->charlcd = lcd;
317
318 /* Required properties */
319 err = device_property_read_u32(&i2c->dev, "display-height-chars",
320 &lcd->height);
321 if (err)
322 goto fail1;
323
324 err = device_property_read_u32(&i2c->dev, "display-width-chars",
325 &lcd->width);
326 if (err)
327 goto fail1;
328
329 lcd->ops = &lcd2s_ops;
330
331 err = charlcd_register(lcd2s->charlcd);
332 if (err)
333 goto fail1;
334
335 i2c_set_clientdata(i2c, lcd2s);
336 return 0;
337
338 fail1:
339 charlcd_free(lcd2s->charlcd);
340 return err;
341 }
342
lcd2s_i2c_remove(struct i2c_client * i2c)343 static void lcd2s_i2c_remove(struct i2c_client *i2c)
344 {
345 struct lcd2s_data *lcd2s = i2c_get_clientdata(i2c);
346
347 charlcd_unregister(lcd2s->charlcd);
348 charlcd_free(lcd2s->charlcd);
349 }
350
351 static const struct i2c_device_id lcd2s_i2c_id[] = {
352 { "lcd2s", 0 },
353 { }
354 };
355 MODULE_DEVICE_TABLE(i2c, lcd2s_i2c_id);
356
357 static const struct of_device_id lcd2s_of_table[] = {
358 { .compatible = "modtronix,lcd2s" },
359 { }
360 };
361 MODULE_DEVICE_TABLE(of, lcd2s_of_table);
362
363 static struct i2c_driver lcd2s_i2c_driver = {
364 .driver = {
365 .name = "lcd2s",
366 .of_match_table = lcd2s_of_table,
367 },
368 .probe = lcd2s_i2c_probe,
369 .remove = lcd2s_i2c_remove,
370 .id_table = lcd2s_i2c_id,
371 };
372 module_i2c_driver(lcd2s_i2c_driver);
373
374 MODULE_DESCRIPTION("LCD2S character display driver");
375 MODULE_AUTHOR("Lars Poeschel");
376 MODULE_LICENSE("GPL");
377
