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
  24 struct ad2s90_state {
  25         struct mutex lock; /* lock to protect rx buffer */
  26         struct spi_device *sdev;
  27         u8 rx[2] ____cacheline_aligned;
  28 };
  29
  30 static 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
  67 static const struct iio_info ad2s90_info = {
  68         .read_raw = ad2s90_read_raw,
  69 };
  70
  71 static 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
  78 static 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
 106 static const struct of_device_id ad2s90_of_match[] = {
 107         { .compatible = "adi,ad2s90", },
 108         {}
 109 };
 110 MODULE_DEVICE_TABLE(of, ad2s90_of_match);
 111
 112 static const struct spi_device_id ad2s90_id[] = {
 113         { "ad2s90" },
 114         {}
 115 };
 116 MODULE_DEVICE_TABLE(spi, ad2s90_id);
 117
 118 static 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 };
 126 module_spi_driver(ad2s90_driver);
 127
 128 MODULE_AUTHOR("Graff Yang <graff.yang@gmail.com>");
 129 MODULE_DESCRIPTION("Analog Devices AD2S90 Resolver to Digital SPI driver");
 130 MODULE_LICENSE("GPL v2");