drivers/staging/iio/resolver/ad2s90.c

   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 "../iio.h"
  20 #include "../sysfs.h"
  21
  22 struct ad2s90_state {
  23         struct mutex lock;
  24         struct spi_device *sdev;
  25         u8 rx[2] ____cacheline_aligned;
  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 };
  59
  60 static int __devinit ad2s90_probe(struct spi_device *spi)
  61 {
  62         struct iio_dev *indio_dev;
  63         struct ad2s90_state *st;
  64         int ret = 0;
  65
  66         indio_dev = iio_allocate_device(sizeof(*st));
  67         if (indio_dev == NULL) {
  68                 ret = -ENOMEM;
  69                 goto error_ret;
  70         }
  71         st = iio_priv(indio_dev);
  72         spi_set_drvdata(spi, indio_dev);
  73
  74         mutex_init(&st->lock);
  75         st->sdev = spi;
  76         indio_dev->dev.parent = &spi->dev;
  77         indio_dev->info = &ad2s90_info;
  78         indio_dev->modes = INDIO_DIRECT_MODE;
  79         indio_dev->channels = &ad2s90_chan;
  80         indio_dev->num_channels = 1;
  81         indio_dev->name = spi_get_device_id(spi)->name;
  82
  83         ret = iio_device_register(indio_dev);
  84         if (ret)
  85                 goto error_free_dev;
  86
  87         /* need 600ns between CS and the first falling edge of SCLK */
  88         spi->max_speed_hz = 830000;
  89         spi->mode = SPI_MODE_3;
  90         spi_setup(spi);
  91
  92         return 0;
  93
  94 error_free_dev:
  95         iio_free_device(indio_dev);
  96 error_ret:
  97         return ret;
  98 }
  99
 100 static int __devexit ad2s90_remove(struct spi_device *spi)
 101 {
 102         iio_device_unregister(spi_get_drvdata(spi));
 103         iio_free_device(spi_get_drvdata(spi));
 104
 105         return 0;
 106 }
 107
 108 static const struct spi_device_id ad2s90_id[] = {
 109         { "ad2s90" },
 110         {}
 111 };
 112 MODULE_DEVICE_TABLE(spi, ad2s90_id);
 113
 114 static struct spi_driver ad2s90_driver = {
 115         .driver = {
 116                 .name = "ad2s90",
 117                 .owner = THIS_MODULE,
 118         },
 119         .probe = ad2s90_probe,
 120         .remove = __devexit_p(ad2s90_remove),
 121         .id_table = ad2s90_id,
 122 };
 123 module_spi_driver(ad2s90_driver);
 124
 125 MODULE_AUTHOR("Graff Yang <graff.yang@gmail.com>");
 126 MODULE_DESCRIPTION("Analog Devices AD2S90 Resolver to Digital SPI driver");
 127 MODULE_LICENSE("GPL v2");