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];
  28         u8 tx[2];
  29 };
  30
  31 static ssize_t ad2s90_show_angular(struct device *dev,
  32                         struct device_attribute *attr, char *buf)
  33 {
  34         struct spi_message msg;
  35         struct spi_transfer xfer;
  36         int ret;
  37         ssize_t len = 0;
  38         u16 val;
  39         struct iio_dev *idev = dev_get_drvdata(dev);
  40         struct ad2s90_state *st = idev->dev_data;
  41
  42         xfer.len = 1;
  43         xfer.tx_buf = st->tx;
  44         xfer.rx_buf = st->rx;
  45         mutex_lock(&st->lock);
  46
  47         spi_message_init(&msg);
  48         spi_message_add_tail(&xfer, &msg);
  49         ret = spi_sync(st->sdev, &msg);
  50         if (ret)
  51                 goto error_ret;
  52         val = (((u16)(st->rx[0])) << 4) | ((st->rx[1] & 0xF0) >> 4);
  53         len = sprintf(buf, "%d\n", val);
  54 error_ret:
  55         mutex_unlock(&st->lock);
  56
  57         return ret ? ret : len;
  58 }
  59
  60 #define IIO_DEV_ATTR_SIMPLE_RESOLVER(_show) \
  61         IIO_DEVICE_ATTR(angular, S_IRUGO, _show, NULL, 0)
  62
  63 static IIO_CONST_ATTR(description,
  64         "Low Cost, Complete 12-Bit Resolver-to-Digital Converter");
  65 static IIO_DEV_ATTR_SIMPLE_RESOLVER(ad2s90_show_angular);
  66
  67 static struct attribute *ad2s90_attributes[] = {
  68         &iio_const_attr_description.dev_attr.attr,
  69         &iio_dev_attr_angular.dev_attr.attr,
  70         NULL,
  71 };
  72
  73 static const struct attribute_group ad2s90_attribute_group = {
  74         .name = DRV_NAME,
  75         .attrs = ad2s90_attributes,
  76 };
  77
  78 static int __devinit ad2s90_probe(struct spi_device *spi)
  79 {
  80         struct ad2s90_state *st;
  81         int ret = 0;
  82
  83         st = kzalloc(sizeof(*st), GFP_KERNEL);
  84         if (st == NULL) {
  85                 ret = -ENOMEM;
  86                 goto error_ret;
  87         }
  88         spi_set_drvdata(spi, st);
  89
  90         mutex_init(&st->lock);
  91         st->sdev = spi;
  92
  93         st->idev = iio_allocate_device();
  94         if (st->idev == NULL) {
  95                 ret = -ENOMEM;
  96                 goto error_free_st;
  97         }
  98         st->idev->dev.parent = &spi->dev;
  99         st->idev->num_interrupt_lines = 0;
 100         st->idev->event_attrs = NULL;
 101
 102         st->idev->attrs = &ad2s90_attribute_group;
 103         st->idev->dev_data = (void *)(st);
 104         st->idev->driver_module = THIS_MODULE;
 105         st->idev->modes = INDIO_DIRECT_MODE;
 106
 107         ret = iio_device_register(st->idev);
 108         if (ret)
 109                 goto error_free_dev;
 110
 111         /* need 600ns between CS and the first falling edge of SCLK */
 112         spi->max_speed_hz = 830000;
 113         spi->mode = SPI_MODE_3;
 114         spi_setup(spi);
 115
 116         return 0;
 117
 118 error_free_dev:
 119         iio_free_device(st->idev);
 120 error_free_st:
 121         kfree(st);
 122 error_ret:
 123         return ret;
 124 }
 125
 126 static int __devexit ad2s90_remove(struct spi_device *spi)
 127 {
 128         struct ad2s90_state *st = spi_get_drvdata(spi);
 129
 130         iio_device_unregister(st->idev);
 131         kfree(st);
 132
 133         return 0;
 134 }
 135
 136 static struct spi_driver ad2s90_driver = {
 137         .driver = {
 138                 .name = DRV_NAME,
 139                 .owner = THIS_MODULE,
 140         },
 141         .probe = ad2s90_probe,
 142         .remove = __devexit_p(ad2s90_remove),
 143 };
 144
 145 static __init int ad2s90_spi_init(void)
 146 {
 147         return spi_register_driver(&ad2s90_driver);
 148 }
 149 module_init(ad2s90_spi_init);
 150
 151 static __exit void ad2s90_spi_exit(void)
 152 {
 153         spi_unregister_driver(&ad2s90_driver);
 154 }
 155 module_exit(ad2s90_spi_exit);
 156
 157 MODULE_AUTHOR("Graff Yang <graff.yang@gmail.com>");
 158 MODULE_DESCRIPTION("Analog Devices AD2S90 Resolver to Digital SPI driver");
 159 MODULE_LICENSE("GPL v2");