1/*
2 * Copyright (C) 2006 Juergen Beisert, Pengutronix
3 * Copyright (C) 2008 Guennadi Liakhovetski, Pengutronix
4 * Copyright (C) 2009 Wolfram Sang, Pengutronix
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 as
8 * published by the Free Software Foundation.
9 *
10 * Check max730x.c for further details.
11 */
12
13#include <linux/module.h>
14#include <linux/init.h>
15#include <linux/platform_device.h>
16#include <linux/mutex.h>
17#include <linux/slab.h>
18#include <linux/spi/spi.h>
19#include <linux/spi/max7301.h>
20
21/* A write to the MAX7301 means one message with one transfer */
22static int max7301_spi_write(struct device *dev, unsigned int reg,
23				unsigned int val)
24{
25	struct spi_device *spi = to_spi_device(dev);
26	u16 word = ((reg & 0x7F) << 8) | (val & 0xFF);
27
28	return spi_write(spi, (const u8 *)&word, sizeof(word));
29}
30
31/* A read from the MAX7301 means two transfers; here, one message each */
32
33static int max7301_spi_read(struct device *dev, unsigned int reg)
34{
35	int ret;
36	u16 word;
37	struct spi_device *spi = to_spi_device(dev);
38
39	word = 0x8000 | (reg << 8);
40	ret = spi_write(spi, (const u8 *)&word, sizeof(word));
41	if (ret)
42		return ret;
43	/*
44	 * This relies on the fact, that a transfer with NULL tx_buf shifts out
45	 * zero bytes (=NOOP for MAX7301)
46	 */
47	ret = spi_read(spi, (u8 *)&word, sizeof(word));
48	if (ret)
49		return ret;
50	return word & 0xff;
51}
52
53static int max7301_probe(struct spi_device *spi)
54{
55	struct max7301 *ts;
56	int ret;
57
58	/* bits_per_word cannot be configured in platform data */
59	spi->bits_per_word = 16;
60	ret = spi_setup(spi);
61	if (ret < 0)
62		return ret;
63
64	ts = devm_kzalloc(&spi->dev, sizeof(struct max7301), GFP_KERNEL);
65	if (!ts)
66		return -ENOMEM;
67
68	ts->read = max7301_spi_read;
69	ts->write = max7301_spi_write;
70	ts->dev = &spi->dev;
71
72	ret = __max730x_probe(ts);
73	return ret;
74}
75
76static int max7301_remove(struct spi_device *spi)
77{
78	return __max730x_remove(&spi->dev);
79}
80
81static const struct spi_device_id max7301_id[] = {
82	{ "max7301", 0 },
83	{ }
84};
85MODULE_DEVICE_TABLE(spi, max7301_id);
86
87static struct spi_driver max7301_driver = {
88	.driver = {
89		.name = "max7301",
90		.owner = THIS_MODULE,
91	},
92	.probe = max7301_probe,
93	.remove = max7301_remove,
94	.id_table = max7301_id,
95};
96
97static int __init max7301_init(void)
98{
99	return spi_register_driver(&max7301_driver);
100}
101/* register after spi postcore initcall and before
102 * subsys initcalls that may rely on these GPIOs
103 */
104subsys_initcall(max7301_init);
105
106static void __exit max7301_exit(void)
107{
108	spi_unregister_driver(&max7301_driver);
109}
110module_exit(max7301_exit);
111
112MODULE_AUTHOR("Juergen Beisert, Wolfram Sang");
113MODULE_LICENSE("GPL v2");
114MODULE_DESCRIPTION("MAX7301 GPIO-Expander");
115