drivers/staging/iio/resolver/ad2s1200.c

   1 /*
   2  * ad2s1200.c simple support for the ADI Resolver to Digital Converters:
   3  * AD2S1200/1205
   4  *
   5  * Copyright (c) 2010-2010 Analog Devices Inc.
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License version 2 as
   9  * published by the Free Software Foundation.
  10  *
  11  */
  12 #include <linux/types.h>
  13 #include <linux/mutex.h>
  14 #include <linux/device.h>
  15 #include <linux/spi/spi.h>
  16 #include <linux/slab.h>
  17 #include <linux/sysfs.h>
  18 #include <linux/delay.h>
  19 #include <linux/gpio.h>
  20 #include <linux/module.h>
  21 #include <linux/bitops.h>
  22
  23 #include <linux/iio/iio.h>
  24 #include <linux/iio/sysfs.h>
  25
  26 #define DRV_NAME "ad2s1200"
  27
  28 /* input pin sample and rdvel is controlled by driver */
  29 #define AD2S1200_PN     2
  30
  31 /* input clock on serial interface */
  32 #define AD2S1200_HZ     8192000
  33 /* clock period in nano second */
  34 #define AD2S1200_TSCLK  (1000000000 / AD2S1200_HZ)
  35
  36 struct ad2s1200_state {
  37         struct mutex lock;
  38         struct spi_device *sdev;
  39         int sample;
  40         int rdvel;
  41         u8 rx[2] ____cacheline_aligned;
  42 };
  43
  44 static int ad2s1200_read_raw(struct iio_dev *indio_dev,
  45                              struct iio_chan_spec const *chan,
  46                              int *val,
  47                              int *val2,
  48                              long m)
  49 {
  50         int ret = 0;
  51         s16 vel;
  52         struct ad2s1200_state *st = iio_priv(indio_dev);
  53
  54         mutex_lock(&st->lock);
  55         gpio_set_value(st->sample, 0);
  56         /* delay (6 * AD2S1200_TSCLK + 20) nano seconds */
  57         udelay(1);
  58         gpio_set_value(st->sample, 1);
  59         gpio_set_value(st->rdvel, !!(chan->type == IIO_ANGL));
  60         ret = spi_read(st->sdev, st->rx, 2);
  61         if (ret < 0) {
  62                 mutex_unlock(&st->lock);
  63                 return ret;
  64         }
  65
  66         switch (chan->type) {
  67         case IIO_ANGL:
  68                 *val = (((u16)(st->rx[0])) << 4) | ((st->rx[1] & 0xF0) >> 4);
  69                 break;
  70         case IIO_ANGL_VEL:
  71                 vel = (((s16)(st->rx[0])) << 4) | ((st->rx[1] & 0xF0) >> 4);
  72                 vel = sign_extend32(vel, 11);
  73                 *val = vel;
  74                 break;
  75         default:
  76                 mutex_unlock(&st->lock);
  77                 return -EINVAL;
  78         }
  79         /* delay (2 * AD2S1200_TSCLK + 20) ns for sample pulse */
  80         udelay(1);
  81         mutex_unlock(&st->lock);
  82         return IIO_VAL_INT;
  83 }
  84
  85 static const struct iio_chan_spec ad2s1200_channels[] = {
  86         {
  87                 .type = IIO_ANGL,
  88                 .indexed = 1,
  89                 .channel = 0,
  90                 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
  91         }, {
  92                 .type = IIO_ANGL_VEL,
  93                 .indexed = 1,
  94                 .channel = 0,
  95                 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
  96         }
  97 };
  98
  99 static const struct iio_info ad2s1200_info = {
 100         .read_raw = &ad2s1200_read_raw,
 101         .driver_module = THIS_MODULE,
 102 };
 103
 104 static int ad2s1200_probe(struct spi_device *spi)
 105 {
 106         struct ad2s1200_state *st;
 107         struct iio_dev *indio_dev;
 108         int pn, ret = 0;
 109         unsigned short *pins = spi->dev.platform_data;
 110
 111         for (pn = 0; pn < AD2S1200_PN; pn++) {
 112                 ret = devm_gpio_request_one(&spi->dev, pins[pn], GPIOF_DIR_OUT,
 113                                             DRV_NAME);
 114                 if (ret) {
 115                         dev_err(&spi->dev, "request gpio pin %d failed\n",
 116                                 pins[pn]);
 117                         return ret;
 118                 }
 119         }
 120         indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
 121         if (!indio_dev)
 122                 return -ENOMEM;
 123         spi_set_drvdata(spi, indio_dev);
 124         st = iio_priv(indio_dev);
 125         mutex_init(&st->lock);
 126         st->sdev = spi;
 127         st->sample = pins[0];
 128         st->rdvel = pins[1];
 129
 130         indio_dev->dev.parent = &spi->dev;
 131         indio_dev->info = &ad2s1200_info;
 132         indio_dev->modes = INDIO_DIRECT_MODE;
 133         indio_dev->channels = ad2s1200_channels;
 134         indio_dev->num_channels = ARRAY_SIZE(ad2s1200_channels);
 135         indio_dev->name = spi_get_device_id(spi)->name;
 136
 137         ret = devm_iio_device_register(&spi->dev, indio_dev);
 138         if (ret)
 139                 return ret;
 140
 141         spi->max_speed_hz = AD2S1200_HZ;
 142         spi->mode = SPI_MODE_3;
 143         spi_setup(spi);
 144
 145         return 0;
 146 }
 147
 148 static const struct spi_device_id ad2s1200_id[] = {
 149         { "ad2s1200" },
 150         { "ad2s1205" },
 151         {}
 152 };
 153 MODULE_DEVICE_TABLE(spi, ad2s1200_id);
 154
 155 static struct spi_driver ad2s1200_driver = {
 156         .driver = {
 157                 .name = DRV_NAME,
 158         },
 159         .probe = ad2s1200_probe,
 160         .id_table = ad2s1200_id,
 161 };
 162 module_spi_driver(ad2s1200_driver);
 163
 164 MODULE_AUTHOR("Graff Yang <graff.yang@gmail.com>");
 165 MODULE_DESCRIPTION("Analog Devices AD2S1200/1205 Resolver to Digital SPI driver");
 166 MODULE_LICENSE("GPL v2");