1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Copyright (C) 2006 Juergen Beisert, Pengutronix
4 * Copyright (C) 2008 Guennadi Liakhovetski, Pengutronix
5 * Copyright (C) 2009 Wolfram Sang, Pengutronix
6 *
7 * Check max730x.c for further details.
8 */
9
10#include <linux/module.h>
11#include <linux/init.h>
12#include <linux/platform_device.h>
13#include <linux/mutex.h>
14#include <linux/slab.h>
15#include <linux/spi/spi.h>
16#include <linux/spi/max7301.h>
17
18/* A write to the MAX7301 means one message with one transfer */
19static int max7301_spi_write(struct device *dev, unsigned int reg,
20				unsigned int val)
21{
22	struct spi_device *spi = to_spi_device(dev);
23	u16 word = ((reg & 0x7F) << 8) | (val & 0xFF);
24
25	return spi_write_then_read(spi, &word, sizeof(word), NULL, 0);
26}
27
28/* A read from the MAX7301 means two transfers; here, one message each */
29
30static int max7301_spi_read(struct device *dev, unsigned int reg)
31{
32	int ret;
33	u16 word;
34	struct spi_device *spi = to_spi_device(dev);
35
36	word = 0x8000 | (reg << 8);
37	ret = spi_write_then_read(spi, &word, sizeof(word), &word,
38				  sizeof(word));
39	if (ret)
40		return ret;
41	return word & 0xff;
42}
43
44static int max7301_probe(struct spi_device *spi)
45{
46	struct max7301 *ts;
47	int ret;
48
49	/* bits_per_word cannot be configured in platform data */
50	spi->bits_per_word = 16;
51	ret = spi_setup(spi);
52	if (ret < 0)
53		return ret;
54
55	ts = devm_kzalloc(&spi->dev, sizeof(struct max7301), GFP_KERNEL);
56	if (!ts)
57		return -ENOMEM;
58
59	ts->read = max7301_spi_read;
60	ts->write = max7301_spi_write;
61	ts->dev = &spi->dev;
62
63	ret = __max730x_probe(ts);
64	return ret;
65}
66
67static void max7301_remove(struct spi_device *spi)
68{
69	__max730x_remove(&spi->dev);
70}
71
72static const struct spi_device_id max7301_id[] = {
73	{ "max7301", 0 },
74	{ }
75};
76MODULE_DEVICE_TABLE(spi, max7301_id);
77
78static struct spi_driver max7301_driver = {
79	.driver = {
80		.name = "max7301",
81	},
82	.probe = max7301_probe,
83	.remove = max7301_remove,
84	.id_table = max7301_id,
85};
86
87static int __init max7301_init(void)
88{
89	return spi_register_driver(&max7301_driver);
90}
91/* register after spi postcore initcall and before
92 * subsys initcalls that may rely on these GPIOs
93 */
94subsys_initcall(max7301_init);
95
96static void __exit max7301_exit(void)
97{
98	spi_unregister_driver(&max7301_driver);
99}
100module_exit(max7301_exit);
101
102MODULE_AUTHOR("Juergen Beisert, Wolfram Sang");
103MODULE_LICENSE("GPL v2");
104MODULE_DESCRIPTION("MAX7301 GPIO-Expander");
105