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