Linux Kernel  3.7.1
 All Data Structures Namespaces Files Functions Variables Typedefs Enumerations Enumerator Macros Groups Pages
ad2s90.c
Go to the documentation of this file.
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;
26 };
27 
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 = IIO_CHAN_INFO_RAW_SEPARATE_BIT,
59 };
60 
61 static int __devinit 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 = iio_device_alloc(sizeof(*st));
68  if (indio_dev == NULL) {
69  ret = -ENOMEM;
70  goto error_ret;
71  }
72  st = iio_priv(indio_dev);
73  spi_set_drvdata(spi, indio_dev);
74 
75  mutex_init(&st->lock);
76  st->sdev = spi;
77  indio_dev->dev.parent = &spi->dev;
78  indio_dev->info = &ad2s90_info;
79  indio_dev->modes = INDIO_DIRECT_MODE;
80  indio_dev->channels = &ad2s90_chan;
81  indio_dev->num_channels = 1;
82  indio_dev->name = spi_get_device_id(spi)->name;
83 
84  ret = iio_device_register(indio_dev);
85  if (ret)
86  goto error_free_dev;
87 
88  /* need 600ns between CS and the first falling edge of SCLK */
89  spi->max_speed_hz = 830000;
90  spi->mode = SPI_MODE_3;
91  spi_setup(spi);
92 
93  return 0;
94 
95 error_free_dev:
96  iio_device_free(indio_dev);
97 error_ret:
98  return ret;
99 }
100 
101 static int __devexit ad2s90_remove(struct spi_device *spi)
102 {
103  iio_device_unregister(spi_get_drvdata(spi));
104  iio_device_free(spi_get_drvdata(spi));
105 
106  return 0;
107 }
108 
109 static const struct spi_device_id ad2s90_id[] = {
110  { "ad2s90" },
111  {}
112 };
113 MODULE_DEVICE_TABLE(spi, ad2s90_id);
114 
115 static struct spi_driver ad2s90_driver = {
116  .driver = {
117  .name = "ad2s90",
118  .owner = THIS_MODULE,
119  },
120  .probe = ad2s90_probe,
121  .remove = __devexit_p(ad2s90_remove),
122  .id_table = ad2s90_id,
123 };
124 module_spi_driver(ad2s90_driver);
125 
126 MODULE_AUTHOR("Graff Yang <[email protected]>");
127 MODULE_DESCRIPTION("Analog Devices AD2S90 Resolver to Digital SPI driver");
128 MODULE_LICENSE("GPL v2");