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
  18 #include "../iio.h"
  19 #include "../sysfs.h"
  20
  21 #define DRV_NAME "ad2s90"
  22
  23 struct ad2s90_state {
  24         struct mutex lock;
  25         struct iio_dev *idev;
  26         struct spi_device *sdev;
  27         u8 rx[2] ____cacheline_aligned;
  28 };
  29
  30 static ssize_t ad2s90_show_angular(struct device *dev,
  31                         struct device_attribute *attr, char *buf)
  32 {
  33         int ret;
  34         ssize_t len = 0;
  35         u16 val;
  36         struct ad2s90_state *st = iio_priv(dev_get_drvdata(dev));
  37
  38         mutex_lock(&st->lock);
  39         ret = spi_read(st->sdev, st->rx, 2);
  40         if (ret)
  41                 goto error_ret;
  42         val = (((u16)(st->rx[0])) << 4) | ((st->rx[1] & 0xF0) >> 4);
  43         len = sprintf(buf, "%d\n", val);
  44 error_ret:
  45         mutex_unlock(&st->lock);
  46
  47         return ret ? ret : len;
  48 }
  49
  50 #define IIO_DEV_ATTR_SIMPLE_RESOLVER(_show) \
  51         IIO_DEVICE_ATTR(angular, S_IRUGO, _show, NULL, 0)
  52
  53 static IIO_DEV_ATTR_SIMPLE_RESOLVER(ad2s90_show_angular);
  54
  55 static struct attribute *ad2s90_attributes[] = {
  56         &iio_dev_attr_angular.dev_attr.attr,
  57         NULL,
  58 };
  59
  60 static const struct attribute_group ad2s90_attribute_group = {
  61         .name = DRV_NAME,
  62         .attrs = ad2s90_attributes,
  63 };
  64
  65 static const struct iio_info ad2s90_info = {
  66         .attrs = &ad2s90_attribute_group,
  67         .driver_module = THIS_MODULE,
  68 };
  69
  70 static int __devinit ad2s90_probe(struct spi_device *spi)
  71 {
  72         struct iio_dev *indio_dev;
  73         struct ad2s90_state *st;
  74         int ret = 0;
  75
  76         indio_dev = iio_allocate_device(sizeof(*st));
  77         if (indio_dev == NULL) {
  78                 ret = -ENOMEM;
  79                 goto error_ret;
  80         }
  81         st = iio_priv(indio_dev);
  82         spi_set_drvdata(spi, indio_dev);
  83
  84         mutex_init(&st->lock);
  85         st->sdev = spi;
  86         indio_dev->dev.parent = &spi->dev;
  87         indio_dev->info = &ad2s90_info;
  88         indio_dev->modes = INDIO_DIRECT_MODE;
  89
  90         ret = iio_device_register(st->idev);
  91         if (ret)
  92                 goto error_free_dev;
  93
  94         /* need 600ns between CS and the first falling edge of SCLK */
  95         spi->max_speed_hz = 830000;
  96         spi->mode = SPI_MODE_3;
  97         spi_setup(spi);
  98
  99         return 0;
 100
 101 error_free_dev:
 102         iio_free_device(st->idev);
 103 error_ret:
 104         return ret;
 105 }
 106
 107 static int __devexit ad2s90_remove(struct spi_device *spi)
 108 {
 109         iio_device_unregister(spi_get_drvdata(spi));
 110
 111         return 0;
 112 }
 113
 114 static struct spi_driver ad2s90_driver = {
 115         .driver = {
 116                 .name = DRV_NAME,
 117                 .owner = THIS_MODULE,
 118         },
 119         .probe = ad2s90_probe,
 120         .remove = __devexit_p(ad2s90_remove),
 121 };
 122
 123 static __init int ad2s90_spi_init(void)
 124 {
 125         return spi_register_driver(&ad2s90_driver);
 126 }
 127 module_init(ad2s90_spi_init);
 128
 129 static __exit void ad2s90_spi_exit(void)
 130 {
 131         spi_unregister_driver(&ad2s90_driver);
 132 }
 133 module_exit(ad2s90_spi_exit);
 134
 135 MODULE_AUTHOR("Graff Yang <graff.yang@gmail.com>");
 136 MODULE_DESCRIPTION("Analog Devices AD2S90 Resolver to Digital SPI driver");
 137 MODULE_LICENSE("GPL v2");