xref: /linux/drivers/input/touchscreen/goodix_berlin_spi.c (revision 1f20a5769446a1acae67ac9e63d07a594829a789)
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  * Goodix Berlin Touchscreen Driver
4  *
5  * Copyright (C) 2020 - 2021 Goodix, Inc.
6  * Copyright (C) 2023 Linaro Ltd.
7  *
8  * Based on goodix_ts_berlin driver.
9  */
10 #include <asm/unaligned.h>
11 #include <linux/kernel.h>
12 #include <linux/module.h>
13 #include <linux/regmap.h>
14 #include <linux/spi/spi.h>
15 #include <linux/input.h>
16 
17 #include "goodix_berlin.h"
18 
19 #define GOODIX_BERLIN_SPI_TRANS_PREFIX_LEN	1
20 #define GOODIX_BERLIN_REGISTER_WIDTH		4
21 #define GOODIX_BERLIN_SPI_READ_DUMMY_LEN	3
22 #define GOODIX_BERLIN_SPI_READ_PREFIX_LEN	(GOODIX_BERLIN_SPI_TRANS_PREFIX_LEN + \
23 						 GOODIX_BERLIN_REGISTER_WIDTH + \
24 						 GOODIX_BERLIN_SPI_READ_DUMMY_LEN)
25 #define GOODIX_BERLIN_SPI_WRITE_PREFIX_LEN	(GOODIX_BERLIN_SPI_TRANS_PREFIX_LEN + \
26 						 GOODIX_BERLIN_REGISTER_WIDTH)
27 
28 #define GOODIX_BERLIN_SPI_WRITE_FLAG		0xF0
29 #define GOODIX_BERLIN_SPI_READ_FLAG		0xF1
30 
31 static int goodix_berlin_spi_read(void *context, const void *reg_buf,
32 				  size_t reg_size, void *val_buf,
33 				  size_t val_size)
34 {
35 	struct spi_device *spi = context;
36 	struct spi_transfer xfers;
37 	struct spi_message spi_msg;
38 	const u32 *reg = reg_buf; /* reg is stored as native u32 at start of buffer */
39 	u8 *buf;
40 	int error;
41 
42 	if (reg_size != GOODIX_BERLIN_REGISTER_WIDTH)
43 		return -EINVAL;
44 
45 	buf = kzalloc(GOODIX_BERLIN_SPI_READ_PREFIX_LEN + val_size, GFP_KERNEL);
46 	if (!buf)
47 		return -ENOMEM;
48 
49 	spi_message_init(&spi_msg);
50 	memset(&xfers, 0, sizeof(xfers));
51 
52 	/* buffer format: 0xF1 + addr(4bytes) + dummy(3bytes) + data */
53 	buf[0] = GOODIX_BERLIN_SPI_READ_FLAG;
54 	put_unaligned_be32(*reg, buf + GOODIX_BERLIN_SPI_TRANS_PREFIX_LEN);
55 	memset(buf + GOODIX_BERLIN_SPI_TRANS_PREFIX_LEN + GOODIX_BERLIN_REGISTER_WIDTH,
56 	       0xff, GOODIX_BERLIN_SPI_READ_DUMMY_LEN);
57 
58 	xfers.tx_buf = buf;
59 	xfers.rx_buf = buf;
60 	xfers.len = GOODIX_BERLIN_SPI_READ_PREFIX_LEN + val_size;
61 	xfers.cs_change = 0;
62 	spi_message_add_tail(&xfers, &spi_msg);
63 
64 	error = spi_sync(spi, &spi_msg);
65 	if (error < 0)
66 		dev_err(&spi->dev, "spi transfer error, %d", error);
67 	else
68 		memcpy(val_buf, buf + GOODIX_BERLIN_SPI_READ_PREFIX_LEN, val_size);
69 
70 	kfree(buf);
71 	return error;
72 }
73 
74 static int goodix_berlin_spi_write(void *context, const void *data,
75 				   size_t count)
76 {
77 	unsigned int len = count - GOODIX_BERLIN_REGISTER_WIDTH;
78 	struct spi_device *spi = context;
79 	struct spi_transfer xfers;
80 	struct spi_message spi_msg;
81 	const u32 *reg = data; /* reg is stored as native u32 at start of buffer */
82 	u8 *buf;
83 	int error;
84 
85 	buf = kzalloc(GOODIX_BERLIN_SPI_WRITE_PREFIX_LEN + len, GFP_KERNEL);
86 	if (!buf)
87 		return -ENOMEM;
88 
89 	spi_message_init(&spi_msg);
90 	memset(&xfers, 0, sizeof(xfers));
91 
92 	buf[0] = GOODIX_BERLIN_SPI_WRITE_FLAG;
93 	put_unaligned_be32(*reg, buf + GOODIX_BERLIN_SPI_TRANS_PREFIX_LEN);
94 	memcpy(buf + GOODIX_BERLIN_SPI_WRITE_PREFIX_LEN,
95 	       data + GOODIX_BERLIN_REGISTER_WIDTH, len);
96 
97 	xfers.tx_buf = buf;
98 	xfers.len = GOODIX_BERLIN_SPI_WRITE_PREFIX_LEN + len;
99 	xfers.cs_change = 0;
100 	spi_message_add_tail(&xfers, &spi_msg);
101 
102 	error = spi_sync(spi, &spi_msg);
103 	if (error < 0)
104 		dev_err(&spi->dev, "spi transfer error, %d", error);
105 
106 	kfree(buf);
107 	return error;
108 }
109 
110 static const struct regmap_config goodix_berlin_spi_regmap_conf = {
111 	.reg_bits = 32,
112 	.val_bits = 8,
113 	.read = goodix_berlin_spi_read,
114 	.write = goodix_berlin_spi_write,
115 };
116 
117 /* vendor & product left unassigned here, should probably be updated from fw info */
118 static const struct input_id goodix_berlin_spi_input_id = {
119 	.bustype = BUS_SPI,
120 };
121 
122 static int goodix_berlin_spi_probe(struct spi_device *spi)
123 {
124 	struct regmap_config regmap_config;
125 	struct regmap *regmap;
126 	size_t max_size;
127 	int error = 0;
128 
129 	spi->mode = SPI_MODE_0;
130 	spi->bits_per_word = 8;
131 	error = spi_setup(spi);
132 	if (error)
133 		return error;
134 
135 	max_size = spi_max_transfer_size(spi);
136 
137 	regmap_config = goodix_berlin_spi_regmap_conf;
138 	regmap_config.max_raw_read = max_size - GOODIX_BERLIN_SPI_READ_PREFIX_LEN;
139 	regmap_config.max_raw_write = max_size - GOODIX_BERLIN_SPI_WRITE_PREFIX_LEN;
140 
141 	regmap = devm_regmap_init(&spi->dev, NULL, spi, &regmap_config);
142 	if (IS_ERR(regmap))
143 		return PTR_ERR(regmap);
144 
145 	error = goodix_berlin_probe(&spi->dev, spi->irq,
146 				    &goodix_berlin_spi_input_id, regmap);
147 	if (error)
148 		return error;
149 
150 	return 0;
151 }
152 
153 static const struct spi_device_id goodix_berlin_spi_ids[] = {
154 	{ "gt9916" },
155 	{ },
156 };
157 MODULE_DEVICE_TABLE(spi, goodix_berlin_spi_ids);
158 
159 static const struct of_device_id goodix_berlin_spi_of_match[] = {
160 	{ .compatible = "goodix,gt9916", },
161 	{ }
162 };
163 MODULE_DEVICE_TABLE(of, goodix_berlin_spi_of_match);
164 
165 static struct spi_driver goodix_berlin_spi_driver = {
166 	.driver = {
167 		.name = "goodix-berlin-spi",
168 		.of_match_table = goodix_berlin_spi_of_match,
169 		.pm = pm_sleep_ptr(&goodix_berlin_pm_ops),
170 	},
171 	.probe = goodix_berlin_spi_probe,
172 	.id_table = goodix_berlin_spi_ids,
173 };
174 module_spi_driver(goodix_berlin_spi_driver);
175 
176 MODULE_LICENSE("GPL");
177 MODULE_DESCRIPTION("Goodix Berlin SPI Touchscreen driver");
178 MODULE_AUTHOR("Neil Armstrong <neil.armstrong@linaro.org>");
179