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351f683b | 1 | // SPDX-License-Identifier: GPL-2.0+ |
d47d8836 GU |
2 | /* |
3 | * HD44780 Character LCD driver for Linux | |
4 | * | |
5 | * Copyright (C) 2000-2008, Willy Tarreau <w@1wt.eu> | |
6 | * Copyright (C) 2016-2017 Glider bvba | |
d47d8836 GU |
7 | */ |
8 | ||
9 | #include <linux/delay.h> | |
10 | #include <linux/gpio/consumer.h> | |
11 | #include <linux/module.h> | |
ac316725 | 12 | #include <linux/mod_devicetable.h> |
d47d8836 GU |
13 | #include <linux/platform_device.h> |
14 | #include <linux/property.h> | |
15 | #include <linux/slab.h> | |
16 | ||
75354284 | 17 | #include "charlcd.h" |
d47d8836 GU |
18 | |
19 | enum hd44780_pin { | |
20 | /* Order does matter due to writing to GPIO array subsets! */ | |
21 | PIN_DATA0, /* Optional */ | |
22 | PIN_DATA1, /* Optional */ | |
23 | PIN_DATA2, /* Optional */ | |
24 | PIN_DATA3, /* Optional */ | |
25 | PIN_DATA4, | |
26 | PIN_DATA5, | |
27 | PIN_DATA6, | |
28 | PIN_DATA7, | |
29 | PIN_CTRL_RS, | |
30 | PIN_CTRL_RW, /* Optional */ | |
31 | PIN_CTRL_E, | |
32 | PIN_CTRL_BL, /* Optional */ | |
33 | PIN_NUM | |
34 | }; | |
35 | ||
36 | struct hd44780 { | |
37 | struct gpio_desc *pins[PIN_NUM]; | |
38 | }; | |
39 | ||
40 | static void hd44780_backlight(struct charlcd *lcd, int on) | |
41 | { | |
42 | struct hd44780 *hd = lcd->drvdata; | |
43 | ||
44 | if (hd->pins[PIN_CTRL_BL]) | |
45 | gpiod_set_value_cansleep(hd->pins[PIN_CTRL_BL], on); | |
46 | } | |
47 | ||
48 | static void hd44780_strobe_gpio(struct hd44780 *hd) | |
49 | { | |
50 | /* Maintain the data during 20 us before the strobe */ | |
51 | udelay(20); | |
52 | ||
53 | gpiod_set_value_cansleep(hd->pins[PIN_CTRL_E], 1); | |
54 | ||
55 | /* Maintain the strobe during 40 us */ | |
56 | udelay(40); | |
57 | ||
58 | gpiod_set_value_cansleep(hd->pins[PIN_CTRL_E], 0); | |
59 | } | |
60 | ||
61 | /* write to an LCD panel register in 8 bit GPIO mode */ | |
62 | static void hd44780_write_gpio8(struct hd44780 *hd, u8 val, unsigned int rs) | |
63 | { | |
b9762beb JK |
64 | DECLARE_BITMAP(values, 10); /* for DATA[0-7], RS, RW */ |
65 | unsigned int n; | |
66 | ||
67 | values[0] = val; | |
68 | __assign_bit(8, values, rs); | |
69 | n = hd->pins[PIN_CTRL_RW] ? 10 : 9; | |
d47d8836 GU |
70 | |
71 | /* Present the data to the port */ | |
77588c14 | 72 | gpiod_set_array_value_cansleep(n, &hd->pins[PIN_DATA0], NULL, values); |
d47d8836 GU |
73 | |
74 | hd44780_strobe_gpio(hd); | |
75 | } | |
76 | ||
77 | /* write to an LCD panel register in 4 bit GPIO mode */ | |
78 | static void hd44780_write_gpio4(struct hd44780 *hd, u8 val, unsigned int rs) | |
79 | { | |
b9762beb JK |
80 | DECLARE_BITMAP(values, 6); /* for DATA[4-7], RS, RW */ |
81 | unsigned int n; | |
d47d8836 GU |
82 | |
83 | /* High nibble + RS, RW */ | |
b9762beb JK |
84 | values[0] = val >> 4; |
85 | __assign_bit(4, values, rs); | |
86 | n = hd->pins[PIN_CTRL_RW] ? 6 : 5; | |
d47d8836 GU |
87 | |
88 | /* Present the data to the port */ | |
77588c14 | 89 | gpiod_set_array_value_cansleep(n, &hd->pins[PIN_DATA4], NULL, values); |
d47d8836 GU |
90 | |
91 | hd44780_strobe_gpio(hd); | |
92 | ||
93 | /* Low nibble */ | |
b9762beb JK |
94 | values[0] &= ~0x0fUL; |
95 | values[0] |= val & 0x0f; | |
d47d8836 GU |
96 | |
97 | /* Present the data to the port */ | |
77588c14 | 98 | gpiod_set_array_value_cansleep(n, &hd->pins[PIN_DATA4], NULL, values); |
d47d8836 GU |
99 | |
100 | hd44780_strobe_gpio(hd); | |
101 | } | |
102 | ||
103 | /* Send a command to the LCD panel in 8 bit GPIO mode */ | |
104 | static void hd44780_write_cmd_gpio8(struct charlcd *lcd, int cmd) | |
105 | { | |
106 | struct hd44780 *hd = lcd->drvdata; | |
107 | ||
108 | hd44780_write_gpio8(hd, cmd, 0); | |
109 | ||
110 | /* The shortest command takes at least 120 us */ | |
111 | udelay(120); | |
112 | } | |
113 | ||
114 | /* Send data to the LCD panel in 8 bit GPIO mode */ | |
115 | static void hd44780_write_data_gpio8(struct charlcd *lcd, int data) | |
116 | { | |
117 | struct hd44780 *hd = lcd->drvdata; | |
118 | ||
119 | hd44780_write_gpio8(hd, data, 1); | |
120 | ||
121 | /* The shortest data takes at least 45 us */ | |
122 | udelay(45); | |
123 | } | |
124 | ||
125 | static const struct charlcd_ops hd44780_ops_gpio8 = { | |
126 | .write_cmd = hd44780_write_cmd_gpio8, | |
127 | .write_data = hd44780_write_data_gpio8, | |
128 | .backlight = hd44780_backlight, | |
129 | }; | |
130 | ||
131 | /* Send a command to the LCD panel in 4 bit GPIO mode */ | |
132 | static void hd44780_write_cmd_gpio4(struct charlcd *lcd, int cmd) | |
133 | { | |
134 | struct hd44780 *hd = lcd->drvdata; | |
135 | ||
136 | hd44780_write_gpio4(hd, cmd, 0); | |
137 | ||
138 | /* The shortest command takes at least 120 us */ | |
139 | udelay(120); | |
140 | } | |
141 | ||
142 | /* Send 4-bits of a command to the LCD panel in raw 4 bit GPIO mode */ | |
143 | static void hd44780_write_cmd_raw_gpio4(struct charlcd *lcd, int cmd) | |
144 | { | |
b9762beb | 145 | DECLARE_BITMAP(values, 6); /* for DATA[4-7], RS, RW */ |
d47d8836 | 146 | struct hd44780 *hd = lcd->drvdata; |
b9762beb | 147 | unsigned int n; |
d47d8836 GU |
148 | |
149 | /* Command nibble + RS, RW */ | |
b9762beb JK |
150 | values[0] = cmd & 0x0f; |
151 | n = hd->pins[PIN_CTRL_RW] ? 6 : 5; | |
d47d8836 GU |
152 | |
153 | /* Present the data to the port */ | |
77588c14 | 154 | gpiod_set_array_value_cansleep(n, &hd->pins[PIN_DATA4], NULL, values); |
d47d8836 GU |
155 | |
156 | hd44780_strobe_gpio(hd); | |
157 | } | |
158 | ||
159 | /* Send data to the LCD panel in 4 bit GPIO mode */ | |
160 | static void hd44780_write_data_gpio4(struct charlcd *lcd, int data) | |
161 | { | |
162 | struct hd44780 *hd = lcd->drvdata; | |
163 | ||
164 | hd44780_write_gpio4(hd, data, 1); | |
165 | ||
166 | /* The shortest data takes at least 45 us */ | |
167 | udelay(45); | |
168 | } | |
169 | ||
170 | static const struct charlcd_ops hd44780_ops_gpio4 = { | |
171 | .write_cmd = hd44780_write_cmd_gpio4, | |
172 | .write_cmd_raw4 = hd44780_write_cmd_raw_gpio4, | |
173 | .write_data = hd44780_write_data_gpio4, | |
174 | .backlight = hd44780_backlight, | |
175 | }; | |
176 | ||
177 | static int hd44780_probe(struct platform_device *pdev) | |
178 | { | |
179 | struct device *dev = &pdev->dev; | |
180 | unsigned int i, base; | |
181 | struct charlcd *lcd; | |
182 | struct hd44780 *hd; | |
183 | int ifwidth, ret; | |
184 | ||
185 | /* Required pins */ | |
186 | ifwidth = gpiod_count(dev, "data"); | |
187 | if (ifwidth < 0) | |
188 | return ifwidth; | |
189 | ||
190 | switch (ifwidth) { | |
191 | case 4: | |
192 | base = PIN_DATA4; | |
193 | break; | |
194 | case 8: | |
195 | base = PIN_DATA0; | |
196 | break; | |
197 | default: | |
198 | return -EINVAL; | |
199 | } | |
200 | ||
201 | lcd = charlcd_alloc(sizeof(struct hd44780)); | |
202 | if (!lcd) | |
203 | return -ENOMEM; | |
204 | ||
205 | hd = lcd->drvdata; | |
206 | ||
207 | for (i = 0; i < ifwidth; i++) { | |
208 | hd->pins[base + i] = devm_gpiod_get_index(dev, "data", i, | |
209 | GPIOD_OUT_LOW); | |
210 | if (IS_ERR(hd->pins[base + i])) { | |
211 | ret = PTR_ERR(hd->pins[base + i]); | |
212 | goto fail; | |
213 | } | |
214 | } | |
215 | ||
216 | hd->pins[PIN_CTRL_E] = devm_gpiod_get(dev, "enable", GPIOD_OUT_LOW); | |
217 | if (IS_ERR(hd->pins[PIN_CTRL_E])) { | |
218 | ret = PTR_ERR(hd->pins[PIN_CTRL_E]); | |
219 | goto fail; | |
220 | } | |
221 | ||
222 | hd->pins[PIN_CTRL_RS] = devm_gpiod_get(dev, "rs", GPIOD_OUT_HIGH); | |
223 | if (IS_ERR(hd->pins[PIN_CTRL_RS])) { | |
224 | ret = PTR_ERR(hd->pins[PIN_CTRL_RS]); | |
225 | goto fail; | |
226 | } | |
227 | ||
228 | /* Optional pins */ | |
229 | hd->pins[PIN_CTRL_RW] = devm_gpiod_get_optional(dev, "rw", | |
230 | GPIOD_OUT_LOW); | |
231 | if (IS_ERR(hd->pins[PIN_CTRL_RW])) { | |
232 | ret = PTR_ERR(hd->pins[PIN_CTRL_RW]); | |
233 | goto fail; | |
234 | } | |
235 | ||
236 | hd->pins[PIN_CTRL_BL] = devm_gpiod_get_optional(dev, "backlight", | |
237 | GPIOD_OUT_LOW); | |
238 | if (IS_ERR(hd->pins[PIN_CTRL_BL])) { | |
239 | ret = PTR_ERR(hd->pins[PIN_CTRL_BL]); | |
240 | goto fail; | |
241 | } | |
242 | ||
243 | /* Required properties */ | |
c7c3f096 GU |
244 | ret = device_property_read_u32(dev, "display-height-chars", |
245 | &lcd->height); | |
d47d8836 GU |
246 | if (ret) |
247 | goto fail; | |
c7c3f096 | 248 | ret = device_property_read_u32(dev, "display-width-chars", &lcd->width); |
d47d8836 GU |
249 | if (ret) |
250 | goto fail; | |
251 | ||
252 | /* | |
253 | * On displays with more than two rows, the internal buffer width is | |
254 | * usually equal to the display width | |
255 | */ | |
256 | if (lcd->height > 2) | |
257 | lcd->bwidth = lcd->width; | |
258 | ||
259 | /* Optional properties */ | |
260 | device_property_read_u32(dev, "internal-buffer-width", &lcd->bwidth); | |
261 | ||
262 | lcd->ifwidth = ifwidth; | |
263 | lcd->ops = ifwidth == 8 ? &hd44780_ops_gpio8 : &hd44780_ops_gpio4; | |
264 | ||
265 | ret = charlcd_register(lcd); | |
266 | if (ret) | |
267 | goto fail; | |
268 | ||
269 | platform_set_drvdata(pdev, lcd); | |
270 | return 0; | |
271 | ||
272 | fail: | |
cb79eb95 | 273 | charlcd_free(lcd); |
d47d8836 GU |
274 | return ret; |
275 | } | |
276 | ||
277 | static int hd44780_remove(struct platform_device *pdev) | |
278 | { | |
279 | struct charlcd *lcd = platform_get_drvdata(pdev); | |
280 | ||
281 | charlcd_unregister(lcd); | |
41c8d0ad | 282 | |
cb79eb95 | 283 | charlcd_free(lcd); |
d47d8836 GU |
284 | return 0; |
285 | } | |
286 | ||
287 | static const struct of_device_id hd44780_of_match[] = { | |
288 | { .compatible = "hit,hd44780" }, | |
289 | { /* sentinel */ } | |
290 | }; | |
291 | MODULE_DEVICE_TABLE(of, hd44780_of_match); | |
292 | ||
293 | static struct platform_driver hd44780_driver = { | |
294 | .probe = hd44780_probe, | |
295 | .remove = hd44780_remove, | |
296 | .driver = { | |
297 | .name = "hd44780", | |
298 | .of_match_table = hd44780_of_match, | |
299 | }, | |
300 | }; | |
301 | ||
302 | module_platform_driver(hd44780_driver); | |
303 | MODULE_DESCRIPTION("HD44780 Character LCD driver"); | |
304 | MODULE_AUTHOR("Geert Uytterhoeven <geert@linux-m68k.org>"); | |
305 | MODULE_LICENSE("GPL"); |