1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
|
/*
* HD44780 Character LCD driver for Linux
*
* Copyright (C) 2000-2008, Willy Tarreau <w@1wt.eu>
* Copyright (C) 2016-2017 Glider bvba
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
#include <linux/delay.h>
#include <linux/gpio/consumer.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/property.h>
#include <linux/slab.h>
#include <misc/charlcd.h>
enum hd44780_pin {
/* Order does matter due to writing to GPIO array subsets! */
PIN_DATA0, /* Optional */
PIN_DATA1, /* Optional */
PIN_DATA2, /* Optional */
PIN_DATA3, /* Optional */
PIN_DATA4,
PIN_DATA5,
PIN_DATA6,
PIN_DATA7,
PIN_CTRL_RS,
PIN_CTRL_RW, /* Optional */
PIN_CTRL_E,
PIN_CTRL_BL, /* Optional */
PIN_NUM
};
struct hd44780 {
struct gpio_desc *pins[PIN_NUM];
};
static void hd44780_backlight(struct charlcd *lcd, int on)
{
struct hd44780 *hd = lcd->drvdata;
if (hd->pins[PIN_CTRL_BL])
gpiod_set_value_cansleep(hd->pins[PIN_CTRL_BL], on);
}
static void hd44780_strobe_gpio(struct hd44780 *hd)
{
/* Maintain the data during 20 us before the strobe */
udelay(20);
gpiod_set_value_cansleep(hd->pins[PIN_CTRL_E], 1);
/* Maintain the strobe during 40 us */
udelay(40);
gpiod_set_value_cansleep(hd->pins[PIN_CTRL_E], 0);
}
/* write to an LCD panel register in 8 bit GPIO mode */
static void hd44780_write_gpio8(struct hd44780 *hd, u8 val, unsigned int rs)
{
int values[10]; /* for DATA[0-7], RS, RW */
unsigned int i, n;
for (i = 0; i < 8; i++)
values[PIN_DATA0 + i] = !!(val & BIT(i));
values[PIN_CTRL_RS] = rs;
n = 9;
if (hd->pins[PIN_CTRL_RW]) {
values[PIN_CTRL_RW] = 0;
n++;
}
/* Present the data to the port */
gpiod_set_array_value_cansleep(n, &hd->pins[PIN_DATA0], values);
hd44780_strobe_gpio(hd);
}
/* write to an LCD panel register in 4 bit GPIO mode */
static void hd44780_write_gpio4(struct hd44780 *hd, u8 val, unsigned int rs)
{
int values[10]; /* for DATA[0-7], RS, RW, but DATA[0-3] is unused */
unsigned int i, n;
/* High nibble + RS, RW */
for (i = 4; i < 8; i++)
values[PIN_DATA0 + i] = !!(val & BIT(i));
values[PIN_CTRL_RS] = rs;
n = 5;
if (hd->pins[PIN_CTRL_RW]) {
values[PIN_CTRL_RW] = 0;
n++;
}
/* Present the data to the port */
gpiod_set_array_value_cansleep(n, &hd->pins[PIN_DATA4],
&values[PIN_DATA4]);
hd44780_strobe_gpio(hd);
/* Low nibble */
for (i = 0; i < 4; i++)
values[PIN_DATA4 + i] = !!(val & BIT(i));
/* Present the data to the port */
gpiod_set_array_value_cansleep(n, &hd->pins[PIN_DATA4],
&values[PIN_DATA4]);
hd44780_strobe_gpio(hd);
}
/* Send a command to the LCD panel in 8 bit GPIO mode */
static void hd44780_write_cmd_gpio8(struct charlcd *lcd, int cmd)
{
struct hd44780 *hd = lcd->drvdata;
hd44780_write_gpio8(hd, cmd, 0);
/* The shortest command takes at least 120 us */
udelay(120);
}
/* Send data to the LCD panel in 8 bit GPIO mode */
static void hd44780_write_data_gpio8(struct charlcd *lcd, int data)
{
struct hd44780 *hd = lcd->drvdata;
hd44780_write_gpio8(hd, data, 1);
/* The shortest data takes at least 45 us */
udelay(45);
}
static const struct charlcd_ops hd44780_ops_gpio8 = {
.write_cmd = hd44780_write_cmd_gpio8,
.write_data = hd44780_write_data_gpio8,
.backlight = hd44780_backlight,
};
/* Send a command to the LCD panel in 4 bit GPIO mode */
static void hd44780_write_cmd_gpio4(struct charlcd *lcd, int cmd)
{
struct hd44780 *hd = lcd->drvdata;
hd44780_write_gpio4(hd, cmd, 0);
/* The shortest command takes at least 120 us */
udelay(120);
}
/* Send 4-bits of a command to the LCD panel in raw 4 bit GPIO mode */
static void hd44780_write_cmd_raw_gpio4(struct charlcd *lcd, int cmd)
{
int values[10]; /* for DATA[0-7], RS, RW, but DATA[0-3] is unused */
struct hd44780 *hd = lcd->drvdata;
unsigned int i, n;
/* Command nibble + RS, RW */
for (i = 0; i < 4; i++)
values[PIN_DATA4 + i] = !!(cmd & BIT(i));
values[PIN_CTRL_RS] = 0;
n = 5;
if (hd->pins[PIN_CTRL_RW]) {
values[PIN_CTRL_RW] = 0;
n++;
}
/* Present the data to the port */
gpiod_set_array_value_cansleep(n, &hd->pins[PIN_DATA4],
&values[PIN_DATA4]);
hd44780_strobe_gpio(hd);
}
/* Send data to the LCD panel in 4 bit GPIO mode */
static void hd44780_write_data_gpio4(struct charlcd *lcd, int data)
{
struct hd44780 *hd = lcd->drvdata;
hd44780_write_gpio4(hd, data, 1);
/* The shortest data takes at least 45 us */
udelay(45);
}
static const struct charlcd_ops hd44780_ops_gpio4 = {
.write_cmd = hd44780_write_cmd_gpio4,
.write_cmd_raw4 = hd44780_write_cmd_raw_gpio4,
.write_data = hd44780_write_data_gpio4,
.backlight = hd44780_backlight,
};
static int hd44780_probe(struct platform_device *pdev)
{
struct device *dev = &pdev->dev;
unsigned int i, base;
struct charlcd *lcd;
struct hd44780 *hd;
int ifwidth, ret;
/* Required pins */
ifwidth = gpiod_count(dev, "data");
if (ifwidth < 0)
return ifwidth;
switch (ifwidth) {
case 4:
base = PIN_DATA4;
break;
case 8:
base = PIN_DATA0;
break;
default:
return -EINVAL;
}
lcd = charlcd_alloc(sizeof(struct hd44780));
if (!lcd)
return -ENOMEM;
hd = lcd->drvdata;
for (i = 0; i < ifwidth; i++) {
hd->pins[base + i] = devm_gpiod_get_index(dev, "data", i,
GPIOD_OUT_LOW);
if (IS_ERR(hd->pins[base + i])) {
ret = PTR_ERR(hd->pins[base + i]);
goto fail;
}
}
hd->pins[PIN_CTRL_E] = devm_gpiod_get(dev, "enable", GPIOD_OUT_LOW);
if (IS_ERR(hd->pins[PIN_CTRL_E])) {
ret = PTR_ERR(hd->pins[PIN_CTRL_E]);
goto fail;
}
hd->pins[PIN_CTRL_RS] = devm_gpiod_get(dev, "rs", GPIOD_OUT_HIGH);
if (IS_ERR(hd->pins[PIN_CTRL_RS])) {
ret = PTR_ERR(hd->pins[PIN_CTRL_RS]);
goto fail;
}
/* Optional pins */
hd->pins[PIN_CTRL_RW] = devm_gpiod_get_optional(dev, "rw",
GPIOD_OUT_LOW);
if (IS_ERR(hd->pins[PIN_CTRL_RW])) {
ret = PTR_ERR(hd->pins[PIN_CTRL_RW]);
goto fail;
}
hd->pins[PIN_CTRL_BL] = devm_gpiod_get_optional(dev, "backlight",
GPIOD_OUT_LOW);
if (IS_ERR(hd->pins[PIN_CTRL_BL])) {
ret = PTR_ERR(hd->pins[PIN_CTRL_BL]);
goto fail;
}
/* Required properties */
ret = device_property_read_u32(dev, "display-height", &lcd->height);
if (ret)
goto fail;
ret = device_property_read_u32(dev, "display-width", &lcd->width);
if (ret)
goto fail;
/*
* On displays with more than two rows, the internal buffer width is
* usually equal to the display width
*/
if (lcd->height > 2)
lcd->bwidth = lcd->width;
/* Optional properties */
device_property_read_u32(dev, "internal-buffer-width", &lcd->bwidth);
lcd->ifwidth = ifwidth;
lcd->ops = ifwidth == 8 ? &hd44780_ops_gpio8 : &hd44780_ops_gpio4;
ret = charlcd_register(lcd);
if (ret)
goto fail;
platform_set_drvdata(pdev, lcd);
return 0;
fail:
kfree(lcd);
return ret;
}
static int hd44780_remove(struct platform_device *pdev)
{
struct charlcd *lcd = platform_get_drvdata(pdev);
charlcd_unregister(lcd);
return 0;
}
static const struct of_device_id hd44780_of_match[] = {
{ .compatible = "hit,hd44780" },
{ /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, hd44780_of_match);
static struct platform_driver hd44780_driver = {
.probe = hd44780_probe,
.remove = hd44780_remove,
.driver = {
.name = "hd44780",
.of_match_table = hd44780_of_match,
},
};
module_platform_driver(hd44780_driver);
MODULE_DESCRIPTION("HD44780 Character LCD driver");
MODULE_AUTHOR("Geert Uytterhoeven <geert@linux-m68k.org>");
MODULE_LICENSE("GPL");
|
