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 P��schel <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
51struct lcd2s_data {
52	struct i2c_client *i2c;
53	struct charlcd *charlcd;
54};
55
56static 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
74static 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
86static 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
97static 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
106static 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
116static 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
124static 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
139static 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
151static 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
163static 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
173static 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
185static 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
197static 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
209static int lcd2s_fontsize(struct charlcd *lcd, enum charlcd_fontsize size)
210{
211	return 0;
212}
213
214static 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 */
226static 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
264static 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
273static 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
290static 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
338fail1:
339	charlcd_free(lcd2s->charlcd);
340	return err;
341}
342
343static 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
351static const struct i2c_device_id lcd2s_i2c_id[] = {
352	{ "lcd2s", 0 },
353	{ }
354};
355MODULE_DEVICE_TABLE(i2c, lcd2s_i2c_id);
356
357static const struct of_device_id lcd2s_of_table[] = {
358	{ .compatible = "modtronix,lcd2s" },
359	{ }
360};
361MODULE_DEVICE_TABLE(of, lcd2s_of_table);
362
363static 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};
372module_i2c_driver(lcd2s_i2c_driver);
373
374MODULE_DESCRIPTION("LCD2S character display driver");
375MODULE_AUTHOR("Lars Poeschel");
376MODULE_LICENSE("GPL");
377