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, txbuf: &word, n_tx: sizeof(word), NULL, n_rx: 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, txbuf: &word, n_tx: sizeof(word), rxbuf: &word,
38 n_rx: 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(dev: &spi->dev, size: 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(dev: &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(sdrv: &max7301_driver);
99}
100module_exit(max7301_exit);
101
102MODULE_AUTHOR("Juergen Beisert, Wolfram Sang");
103MODULE_LICENSE("GPL v2");
104MODULE_DESCRIPTION("MAX7301 GPIO-Expander");
105

source code of linux/drivers/gpio/gpio-max7301.c