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
 31static 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
 74static 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
110static 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 */
118static const struct input_id goodix_berlin_spi_input_id = {
119	.bustype = BUS_SPI,
120};
121
122static 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
153static const struct spi_device_id goodix_berlin_spi_ids[] = {
154	{ "gt9916" },
155	{ },
156};
157MODULE_DEVICE_TABLE(spi, goodix_berlin_spi_ids);
158
159static const struct of_device_id goodix_berlin_spi_of_match[] = {
160	{ .compatible = "goodix,gt9916", },
161	{ }
162};
163MODULE_DEVICE_TABLE(of, goodix_berlin_spi_of_match);
164
165static 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};
174module_spi_driver(goodix_berlin_spi_driver);
175
176MODULE_LICENSE("GPL");
177MODULE_DESCRIPTION("Goodix Berlin SPI Touchscreen driver");
178MODULE_AUTHOR("Neil Armstrong <neil.armstrong@linaro.org>");