LXR linux/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 <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