LXR linux/drivers/iio/resolver/ad2s90.c

   1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 * ad2s90.c simple support for the ADI Resolver to Digital Converters: AD2S90
   4 *
   5 * Copyright (c) 2010-2010 Analog Devices Inc.
   6 */
   7#include <linux/types.h>
   8#include <linux/mutex.h>
   9#include <linux/device.h>
  10#include <linux/spi/spi.h>
  11#include <linux/slab.h>
  12#include <linux/sysfs.h>
  13#include <linux/module.h>
  14
  15#include <linux/iio/iio.h>
  16#include <linux/iio/sysfs.h>
  17
  18/*
  19 * Although chip's max frequency is 2Mhz, it needs 600ns between CS and the
  20 * first falling edge of SCLK, so frequency should be at most 1 / (2 * 6e-7)
  21 */
  22#define AD2S90_MAX_SPI_FREQ_HZ  830000
  23
  24struct ad2s90_state {
  25        struct mutex lock; /* lock to protect rx buffer */
  26        struct spi_device *sdev;
  27        u8 rx[2] ____cacheline_aligned;
  28};
  29
  30static int ad2s90_read_raw(struct iio_dev *indio_dev,
  31                           struct iio_chan_spec const *chan,
  32                           int *val,
  33                           int *val2,
  34                           long m)
  35{
  36        int ret;
  37        struct ad2s90_state *st = iio_priv(indio_dev);
  38
  39        if (chan->type != IIO_ANGL)
  40                return -EINVAL;
  41
  42        switch (m) {
  43        case IIO_CHAN_INFO_SCALE:
  44                /* 2 * Pi / 2^12 */
  45                *val = 6283; /* mV */
  46                *val2 = 12;
  47                return IIO_VAL_FRACTIONAL_LOG2;
  48        case IIO_CHAN_INFO_RAW:
  49                mutex_lock(&st->lock);
  50                ret = spi_read(st->sdev, st->rx, 2);
  51                if (ret < 0) {
  52                        mutex_unlock(&st->lock);
  53                        return ret;
  54                }
  55                *val = (((u16)(st->rx[0])) << 4) | ((st->rx[1] & 0xF0) >> 4);
  56
  57                mutex_unlock(&st->lock);
  58
  59                return IIO_VAL_INT;
  60        default:
  61                break;
  62        }
  63
  64        return -EINVAL;
  65}
  66
  67static const struct iio_info ad2s90_info = {
  68        .read_raw = ad2s90_read_raw,
  69};
  70
  71static const struct iio_chan_spec ad2s90_chan = {
  72        .type = IIO_ANGL,
  73        .indexed = 1,
  74        .channel = 0,
  75        .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE),
  76};
  77
  78static int ad2s90_probe(struct spi_device *spi)
  79{
  80        struct iio_dev *indio_dev;
  81        struct ad2s90_state *st;
  82
  83        if (spi->max_speed_hz > AD2S90_MAX_SPI_FREQ_HZ) {
  84                dev_err(&spi->dev, "SPI CLK, %d Hz exceeds %d Hz\n",
  85                        spi->max_speed_hz, AD2S90_MAX_SPI_FREQ_HZ);
  86                return -EINVAL;
  87        }
  88
  89        indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
  90        if (!indio_dev)
  91                return -ENOMEM;
  92        st = iio_priv(indio_dev);
  93        spi_set_drvdata(spi, indio_dev);
  94
  95        mutex_init(&st->lock);
  96        st->sdev = spi;
  97        indio_dev->info = &ad2s90_info;
  98        indio_dev->modes = INDIO_DIRECT_MODE;
  99        indio_dev->channels = &ad2s90_chan;
 100        indio_dev->num_channels = 1;
 101        indio_dev->name = spi_get_device_id(spi)->name;
 102
 103        return devm_iio_device_register(indio_dev->dev.parent, indio_dev);
 104}
 105
 106static const struct of_device_id ad2s90_of_match[] = {
 107        { .compatible = "adi,ad2s90", },
 108        {}
 109};
 110MODULE_DEVICE_TABLE(of, ad2s90_of_match);
 111
 112static const struct spi_device_id ad2s90_id[] = {
 113        { "ad2s90" },
 114        {}
 115};
 116MODULE_DEVICE_TABLE(spi, ad2s90_id);
 117
 118static struct spi_driver ad2s90_driver = {
 119        .driver = {
 120                .name = "ad2s90",
 121                .of_match_table = ad2s90_of_match,
 122        },
 123        .probe = ad2s90_probe,
 124        .id_table = ad2s90_id,
 125};
 126module_spi_driver(ad2s90_driver);
 127
 128MODULE_AUTHOR("Graff Yang <graff.yang@gmail.com>");
 129MODULE_DESCRIPTION("Analog Devices AD2S90 Resolver to Digital SPI driver");
 130MODULE_LICENSE("GPL v2");
 131