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d47d8836 GU |
1 | /* |
2 | * HD44780 Character LCD driver for Linux | |
3 | * | |
4 | * Copyright (C) 2000-2008, Willy Tarreau <w@1wt.eu> | |
5 | * Copyright (C) 2016-2017 Glider bvba | |
6 | * | |
7 | * This program is free software; you can redistribute it and/or | |
8 | * modify it under the terms of the GNU General Public License | |
9 | * as published by the Free Software Foundation; either version | |
10 | * 2 of the License, or (at your option) any later version. | |
11 | */ | |
12 | ||
13 | #include <linux/delay.h> | |
14 | #include <linux/gpio/consumer.h> | |
15 | #include <linux/module.h> | |
16 | #include <linux/platform_device.h> | |
17 | #include <linux/property.h> | |
18 | #include <linux/slab.h> | |
19 | ||
20 | #include <misc/charlcd.h> | |
21 | ||
22 | ||
23 | enum hd44780_pin { | |
24 | /* Order does matter due to writing to GPIO array subsets! */ | |
25 | PIN_DATA0, /* Optional */ | |
26 | PIN_DATA1, /* Optional */ | |
27 | PIN_DATA2, /* Optional */ | |
28 | PIN_DATA3, /* Optional */ | |
29 | PIN_DATA4, | |
30 | PIN_DATA5, | |
31 | PIN_DATA6, | |
32 | PIN_DATA7, | |
33 | PIN_CTRL_RS, | |
34 | PIN_CTRL_RW, /* Optional */ | |
35 | PIN_CTRL_E, | |
36 | PIN_CTRL_BL, /* Optional */ | |
37 | PIN_NUM | |
38 | }; | |
39 | ||
40 | struct hd44780 { | |
41 | struct gpio_desc *pins[PIN_NUM]; | |
42 | }; | |
43 | ||
44 | static void hd44780_backlight(struct charlcd *lcd, int on) | |
45 | { | |
46 | struct hd44780 *hd = lcd->drvdata; | |
47 | ||
48 | if (hd->pins[PIN_CTRL_BL]) | |
49 | gpiod_set_value_cansleep(hd->pins[PIN_CTRL_BL], on); | |
50 | } | |
51 | ||
52 | static void hd44780_strobe_gpio(struct hd44780 *hd) | |
53 | { | |
54 | /* Maintain the data during 20 us before the strobe */ | |
55 | udelay(20); | |
56 | ||
57 | gpiod_set_value_cansleep(hd->pins[PIN_CTRL_E], 1); | |
58 | ||
59 | /* Maintain the strobe during 40 us */ | |
60 | udelay(40); | |
61 | ||
62 | gpiod_set_value_cansleep(hd->pins[PIN_CTRL_E], 0); | |
63 | } | |
64 | ||
65 | /* write to an LCD panel register in 8 bit GPIO mode */ | |
66 | static void hd44780_write_gpio8(struct hd44780 *hd, u8 val, unsigned int rs) | |
67 | { | |
68 | int values[10]; /* for DATA[0-7], RS, RW */ | |
69 | unsigned int i, n; | |
70 | ||
71 | for (i = 0; i < 8; i++) | |
72 | values[PIN_DATA0 + i] = !!(val & BIT(i)); | |
73 | values[PIN_CTRL_RS] = rs; | |
74 | n = 9; | |
75 | if (hd->pins[PIN_CTRL_RW]) { | |
76 | values[PIN_CTRL_RW] = 0; | |
77 | n++; | |
78 | } | |
79 | ||
80 | /* Present the data to the port */ | |
81 | gpiod_set_array_value_cansleep(n, &hd->pins[PIN_DATA0], values); | |
82 | ||
83 | hd44780_strobe_gpio(hd); | |
84 | } | |
85 | ||
86 | /* write to an LCD panel register in 4 bit GPIO mode */ | |
87 | static void hd44780_write_gpio4(struct hd44780 *hd, u8 val, unsigned int rs) | |
88 | { | |
89 | int values[10]; /* for DATA[0-7], RS, RW, but DATA[0-3] is unused */ | |
90 | unsigned int i, n; | |
91 | ||
92 | /* High nibble + RS, RW */ | |
93 | for (i = 4; i < 8; i++) | |
94 | values[PIN_DATA0 + i] = !!(val & BIT(i)); | |
95 | values[PIN_CTRL_RS] = rs; | |
96 | n = 5; | |
97 | if (hd->pins[PIN_CTRL_RW]) { | |
98 | values[PIN_CTRL_RW] = 0; | |
99 | n++; | |
100 | } | |
101 | ||
102 | /* Present the data to the port */ | |
103 | gpiod_set_array_value_cansleep(n, &hd->pins[PIN_DATA4], | |
104 | &values[PIN_DATA4]); | |
105 | ||
106 | hd44780_strobe_gpio(hd); | |
107 | ||
108 | /* Low nibble */ | |
109 | for (i = 0; i < 4; i++) | |
110 | values[PIN_DATA4 + i] = !!(val & BIT(i)); | |
111 | ||
112 | /* Present the data to the port */ | |
113 | gpiod_set_array_value_cansleep(n, &hd->pins[PIN_DATA4], | |
114 | &values[PIN_DATA4]); | |
115 | ||
116 | hd44780_strobe_gpio(hd); | |
117 | } | |
118 | ||
119 | /* Send a command to the LCD panel in 8 bit GPIO mode */ | |
120 | static void hd44780_write_cmd_gpio8(struct charlcd *lcd, int cmd) | |
121 | { | |
122 | struct hd44780 *hd = lcd->drvdata; | |
123 | ||
124 | hd44780_write_gpio8(hd, cmd, 0); | |
125 | ||
126 | /* The shortest command takes at least 120 us */ | |
127 | udelay(120); | |
128 | } | |
129 | ||
130 | /* Send data to the LCD panel in 8 bit GPIO mode */ | |
131 | static void hd44780_write_data_gpio8(struct charlcd *lcd, int data) | |
132 | { | |
133 | struct hd44780 *hd = lcd->drvdata; | |
134 | ||
135 | hd44780_write_gpio8(hd, data, 1); | |
136 | ||
137 | /* The shortest data takes at least 45 us */ | |
138 | udelay(45); | |
139 | } | |
140 | ||
141 | static const struct charlcd_ops hd44780_ops_gpio8 = { | |
142 | .write_cmd = hd44780_write_cmd_gpio8, | |
143 | .write_data = hd44780_write_data_gpio8, | |
144 | .backlight = hd44780_backlight, | |
145 | }; | |
146 | ||
147 | /* Send a command to the LCD panel in 4 bit GPIO mode */ | |
148 | static void hd44780_write_cmd_gpio4(struct charlcd *lcd, int cmd) | |
149 | { | |
150 | struct hd44780 *hd = lcd->drvdata; | |
151 | ||
152 | hd44780_write_gpio4(hd, cmd, 0); | |
153 | ||
154 | /* The shortest command takes at least 120 us */ | |
155 | udelay(120); | |
156 | } | |
157 | ||
158 | /* Send 4-bits of a command to the LCD panel in raw 4 bit GPIO mode */ | |
159 | static void hd44780_write_cmd_raw_gpio4(struct charlcd *lcd, int cmd) | |
160 | { | |
161 | int values[10]; /* for DATA[0-7], RS, RW, but DATA[0-3] is unused */ | |
162 | struct hd44780 *hd = lcd->drvdata; | |
163 | unsigned int i, n; | |
164 | ||
165 | /* Command nibble + RS, RW */ | |
166 | for (i = 0; i < 4; i++) | |
167 | values[PIN_DATA4 + i] = !!(cmd & BIT(i)); | |
168 | values[PIN_CTRL_RS] = 0; | |
169 | n = 5; | |
170 | if (hd->pins[PIN_CTRL_RW]) { | |
171 | values[PIN_CTRL_RW] = 0; | |
172 | n++; | |
173 | } | |
174 | ||
175 | /* Present the data to the port */ | |
176 | gpiod_set_array_value_cansleep(n, &hd->pins[PIN_DATA4], | |
177 | &values[PIN_DATA4]); | |
178 | ||
179 | hd44780_strobe_gpio(hd); | |
180 | } | |
181 | ||
182 | /* Send data to the LCD panel in 4 bit GPIO mode */ | |
183 | static void hd44780_write_data_gpio4(struct charlcd *lcd, int data) | |
184 | { | |
185 | struct hd44780 *hd = lcd->drvdata; | |
186 | ||
187 | hd44780_write_gpio4(hd, data, 1); | |
188 | ||
189 | /* The shortest data takes at least 45 us */ | |
190 | udelay(45); | |
191 | } | |
192 | ||
193 | static const struct charlcd_ops hd44780_ops_gpio4 = { | |
194 | .write_cmd = hd44780_write_cmd_gpio4, | |
195 | .write_cmd_raw4 = hd44780_write_cmd_raw_gpio4, | |
196 | .write_data = hd44780_write_data_gpio4, | |
197 | .backlight = hd44780_backlight, | |
198 | }; | |
199 | ||
200 | static int hd44780_probe(struct platform_device *pdev) | |
201 | { | |
202 | struct device *dev = &pdev->dev; | |
203 | unsigned int i, base; | |
204 | struct charlcd *lcd; | |
205 | struct hd44780 *hd; | |
206 | int ifwidth, ret; | |
207 | ||
208 | /* Required pins */ | |
209 | ifwidth = gpiod_count(dev, "data"); | |
210 | if (ifwidth < 0) | |
211 | return ifwidth; | |
212 | ||
213 | switch (ifwidth) { | |
214 | case 4: | |
215 | base = PIN_DATA4; | |
216 | break; | |
217 | case 8: | |
218 | base = PIN_DATA0; | |
219 | break; | |
220 | default: | |
221 | return -EINVAL; | |
222 | } | |
223 | ||
224 | lcd = charlcd_alloc(sizeof(struct hd44780)); | |
225 | if (!lcd) | |
226 | return -ENOMEM; | |
227 | ||
228 | hd = lcd->drvdata; | |
229 | ||
230 | for (i = 0; i < ifwidth; i++) { | |
231 | hd->pins[base + i] = devm_gpiod_get_index(dev, "data", i, | |
232 | GPIOD_OUT_LOW); | |
233 | if (IS_ERR(hd->pins[base + i])) { | |
234 | ret = PTR_ERR(hd->pins[base + i]); | |
235 | goto fail; | |
236 | } | |
237 | } | |
238 | ||
239 | hd->pins[PIN_CTRL_E] = devm_gpiod_get(dev, "enable", GPIOD_OUT_LOW); | |
240 | if (IS_ERR(hd->pins[PIN_CTRL_E])) { | |
241 | ret = PTR_ERR(hd->pins[PIN_CTRL_E]); | |
242 | goto fail; | |
243 | } | |
244 | ||
245 | hd->pins[PIN_CTRL_RS] = devm_gpiod_get(dev, "rs", GPIOD_OUT_HIGH); | |
246 | if (IS_ERR(hd->pins[PIN_CTRL_RS])) { | |
247 | ret = PTR_ERR(hd->pins[PIN_CTRL_RS]); | |
248 | goto fail; | |
249 | } | |
250 | ||
251 | /* Optional pins */ | |
252 | hd->pins[PIN_CTRL_RW] = devm_gpiod_get_optional(dev, "rw", | |
253 | GPIOD_OUT_LOW); | |
254 | if (IS_ERR(hd->pins[PIN_CTRL_RW])) { | |
255 | ret = PTR_ERR(hd->pins[PIN_CTRL_RW]); | |
256 | goto fail; | |
257 | } | |
258 | ||
259 | hd->pins[PIN_CTRL_BL] = devm_gpiod_get_optional(dev, "backlight", | |
260 | GPIOD_OUT_LOW); | |
261 | if (IS_ERR(hd->pins[PIN_CTRL_BL])) { | |
262 | ret = PTR_ERR(hd->pins[PIN_CTRL_BL]); | |
263 | goto fail; | |
264 | } | |
265 | ||
266 | /* Required properties */ | |
c7c3f096 GU |
267 | ret = device_property_read_u32(dev, "display-height-chars", |
268 | &lcd->height); | |
d47d8836 GU |
269 | if (ret) |
270 | goto fail; | |
c7c3f096 | 271 | ret = device_property_read_u32(dev, "display-width-chars", &lcd->width); |
d47d8836 GU |
272 | if (ret) |
273 | goto fail; | |
274 | ||
275 | /* | |
276 | * On displays with more than two rows, the internal buffer width is | |
277 | * usually equal to the display width | |
278 | */ | |
279 | if (lcd->height > 2) | |
280 | lcd->bwidth = lcd->width; | |
281 | ||
282 | /* Optional properties */ | |
283 | device_property_read_u32(dev, "internal-buffer-width", &lcd->bwidth); | |
284 | ||
285 | lcd->ifwidth = ifwidth; | |
286 | lcd->ops = ifwidth == 8 ? &hd44780_ops_gpio8 : &hd44780_ops_gpio4; | |
287 | ||
288 | ret = charlcd_register(lcd); | |
289 | if (ret) | |
290 | goto fail; | |
291 | ||
292 | platform_set_drvdata(pdev, lcd); | |
293 | return 0; | |
294 | ||
295 | fail: | |
296 | kfree(lcd); | |
297 | return ret; | |
298 | } | |
299 | ||
300 | static int hd44780_remove(struct platform_device *pdev) | |
301 | { | |
302 | struct charlcd *lcd = platform_get_drvdata(pdev); | |
303 | ||
304 | charlcd_unregister(lcd); | |
4401ec65 AS |
305 | |
306 | kfree(lcd); | |
d47d8836 GU |
307 | return 0; |
308 | } | |
309 | ||
310 | static const struct of_device_id hd44780_of_match[] = { | |
311 | { .compatible = "hit,hd44780" }, | |
312 | { /* sentinel */ } | |
313 | }; | |
314 | MODULE_DEVICE_TABLE(of, hd44780_of_match); | |
315 | ||
316 | static struct platform_driver hd44780_driver = { | |
317 | .probe = hd44780_probe, | |
318 | .remove = hd44780_remove, | |
319 | .driver = { | |
320 | .name = "hd44780", | |
321 | .of_match_table = hd44780_of_match, | |
322 | }, | |
323 | }; | |
324 | ||
325 | module_platform_driver(hd44780_driver); | |
326 | MODULE_DESCRIPTION("HD44780 Character LCD driver"); | |
327 | MODULE_AUTHOR("Geert Uytterhoeven <geert@linux-m68k.org>"); | |
328 | MODULE_LICENSE("GPL"); |