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
22 struct ad2s90_state {
23 struct mutex lock;
24 struct spi_device *sdev;
25 u8 rx[2] ____cacheline_aligned;
26 };
27
ad2s90_read_raw(struct iio_dev * indio_dev,struct iio_chan_spec const * chan,int * val,int * val2,long m)28 static 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
43 error_ret:
44 mutex_unlock(&st->lock);
45
46 return IIO_VAL_INT;
47 }
48
49 static const struct iio_info ad2s90_info = {
50 .read_raw = &ad2s90_read_raw,
51 .driver_module = THIS_MODULE,
52 };
53
54 static 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
ad2s90_probe(struct spi_device * spi)61 static 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 ret = spi_setup(spi);
90
91 if (ret < 0) {
92 dev_err(&spi->dev, "spi_setup failed!\n");
93 return ret;
94 }
95
96 return 0;
97 }
98
99 static const struct spi_device_id ad2s90_id[] = {
100 { "ad2s90" },
101 {}
102 };
103 MODULE_DEVICE_TABLE(spi, ad2s90_id);
104
105 static struct spi_driver ad2s90_driver = {
106 .driver = {
107 .name = "ad2s90",
108 },
109 .probe = ad2s90_probe,
110 .id_table = ad2s90_id,
111 };
112 module_spi_driver(ad2s90_driver);
113
114 MODULE_AUTHOR("Graff Yang <graff.yang@gmail.com>");
115 MODULE_DESCRIPTION("Analog Devices AD2S90 Resolver to Digital SPI driver");
116 MODULE_LICENSE("GPL v2");
117