1/*
2 * ad2s90.c simple support for the ADI Resolver to Digital Converters: AD2S90
3 *
4 * Copyright (c) 2010-2010 Analog Devices Inc.
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 */
11#include <linux/types.h>
12#include <linux/mutex.h>
13#include <linux/device.h>
14#include <linux/spi/spi.h>
15#include <linux/slab.h>
16#include <linux/sysfs.h>
17#include <linux/module.h>
18
19#include <linux/iio/iio.h>
20#include <linux/iio/sysfs.h>
21
22struct ad2s90_state {
23	struct mutex lock;
24	struct spi_device *sdev;
25	u8 rx[2] ____cacheline_aligned;
26};
27
28static int ad2s90_read_raw(struct iio_dev *indio_dev,
29			   struct iio_chan_spec const *chan,
30			   int *val,
31			   int *val2,
32			   long m)
33{
34	int ret;
35	struct ad2s90_state *st = iio_priv(indio_dev);
36
37	mutex_lock(&st->lock);
38	ret = spi_read(st->sdev, st->rx, 2);
39	if (ret)
40		goto error_ret;
41	*val = (((u16)(st->rx[0])) << 4) | ((st->rx[1] & 0xF0) >> 4);
42
43error_ret:
44	mutex_unlock(&st->lock);
45
46	return IIO_VAL_INT;
47}
48
49static const struct iio_info ad2s90_info = {
50	.read_raw = &ad2s90_read_raw,
51	.driver_module = THIS_MODULE,
52};
53
54static const struct iio_chan_spec ad2s90_chan = {
55	.type = IIO_ANGL,
56	.indexed = 1,
57	.channel = 0,
58	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
59};
60
61static int ad2s90_probe(struct spi_device *spi)
62{
63	struct iio_dev *indio_dev;
64	struct ad2s90_state *st;
65	int ret = 0;
66
67	indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
68	if (!indio_dev)
69		return -ENOMEM;
70	st = iio_priv(indio_dev);
71	spi_set_drvdata(spi, indio_dev);
72
73	mutex_init(&st->lock);
74	st->sdev = spi;
75	indio_dev->dev.parent = &spi->dev;
76	indio_dev->info = &ad2s90_info;
77	indio_dev->modes = INDIO_DIRECT_MODE;
78	indio_dev->channels = &ad2s90_chan;
79	indio_dev->num_channels = 1;
80	indio_dev->name = spi_get_device_id(spi)->name;
81
82	ret = devm_iio_device_register(indio_dev->dev.parent, indio_dev);
83	if (ret)
84		return ret;
85
86	/* need 600ns between CS and the first falling edge of SCLK */
87	spi->max_speed_hz = 830000;
88	spi->mode = SPI_MODE_3;
89	spi_setup(spi);
90
91	return 0;
92}
93
94static const struct spi_device_id ad2s90_id[] = {
95	{ "ad2s90" },
96	{}
97};
98MODULE_DEVICE_TABLE(spi, ad2s90_id);
99
100static struct spi_driver ad2s90_driver = {
101	.driver = {
102		.name = "ad2s90",
103	},
104	.probe = ad2s90_probe,
105	.id_table = ad2s90_id,
106};
107module_spi_driver(ad2s90_driver);
108
109MODULE_AUTHOR("Graff Yang <graff.yang@gmail.com>");
110MODULE_DESCRIPTION("Analog Devices AD2S90 Resolver to Digital SPI driver");
111MODULE_LICENSE("GPL v2");
112