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
  22 #include <linux/iio/iio.h>
  23 #include <linux/iio/sysfs.h>
  24
  25 #define DRV_NAME "ad2s1200"
  26
  27 /* input pin sample and rdvel is controlled by driver */
  28 #define AD2S1200_PN     2
  29
  30 /* input clock on serial interface */
  31 #define AD2S1200_HZ     8192000
  32 /* clock period in nano second */
  33 #define AD2S1200_TSCLK  (1000000000/AD2S1200_HZ)
  34
  35 struct ad2s1200_state {
  36         struct mutex lock;
  37         struct spi_device *sdev;
  38         int sample;
  39         int rdvel;
  40         u8 rx[2] ____cacheline_aligned;
  41 };
  42
  43 static int ad2s1200_read_raw(struct iio_dev *indio_dev,
  44                            struct iio_chan_spec const *chan,
  45                            int *val,
  46                            int *val2,
  47                            long m)
  48 {
  49         int ret = 0;
  50         s16 vel;
  51         struct ad2s1200_state *st = iio_priv(indio_dev);
  52
  53         mutex_lock(&st->lock);
  54         gpio_set_value(st->sample, 0);
  55         /* delay (6 * AD2S1200_TSCLK + 20) nano seconds */
  56         udelay(1);
  57         gpio_set_value(st->sample, 1);
  58         gpio_set_value(st->rdvel, !!(chan->type == IIO_ANGL));
  59         ret = spi_read(st->sdev, st->rx, 2);
  60         if (ret < 0) {
  61                 mutex_unlock(&st->lock);
  62                 return ret;
  63         }
  64
  65         switch (chan->type) {
  66         case IIO_ANGL:
  67                 *val = (((u16)(st->rx[0])) << 4) | ((st->rx[1] & 0xF0) >> 4);
  68                 break;
  69         case IIO_ANGL_VEL:
  70                 vel = (((s16)(st->rx[0])) << 4) | ((st->rx[1] & 0xF0) >> 4);
  71                 vel = (vel << 4) >> 4;
  72                 *val = vel;
  73                 break;
  74         default:
  75                 mutex_unlock(&st->lock);
  76                 return -EINVAL;
  77         }
  78         /* delay (2 * AD2S1200_TSCLK + 20) ns for sample pulse */
  79         udelay(1);
  80         mutex_unlock(&st->lock);
  81         return IIO_VAL_INT;
  82 }
  83
  84 static const struct iio_chan_spec ad2s1200_channels[] = {
  85         {
  86                 .type = IIO_ANGL,
  87                 .indexed = 1,
  88                 .channel = 0,
  89                 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
  90         }, {
  91                 .type = IIO_ANGL_VEL,
  92                 .indexed = 1,
  93                 .channel = 0,
  94                 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
  95         }
  96 };
  97
  98 static const struct iio_info ad2s1200_info = {
  99         .read_raw = &ad2s1200_read_raw,
 100         .driver_module = THIS_MODULE,
 101 };
 102
 103 static int ad2s1200_probe(struct spi_device *spi)
 104 {
 105         struct ad2s1200_state *st;
 106         struct iio_dev *indio_dev;
 107         int pn, ret = 0;
 108         unsigned short *pins = spi->dev.platform_data;
 109
 110         for (pn = 0; pn < AD2S1200_PN; pn++) {
 111                 ret = devm_gpio_request_one(&spi->dev, pins[pn], GPIOF_DIR_OUT,
 112                                             DRV_NAME);
 113                 if (ret) {
 114                         dev_err(&spi->dev, "request gpio pin %d failed\n",
 115                                                         pins[pn]);
 116                         return ret;
 117                 }
 118         }
 119         indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
 120         if (!indio_dev)
 121                 return -ENOMEM;
 122         spi_set_drvdata(spi, indio_dev);
 123         st = iio_priv(indio_dev);
 124         mutex_init(&st->lock);
 125         st->sdev = spi;
 126         st->sample = pins[0];
 127         st->rdvel = pins[1];
 128
 129         indio_dev->dev.parent = &spi->dev;
 130         indio_dev->info = &ad2s1200_info;
 131         indio_dev->modes = INDIO_DIRECT_MODE;
 132         indio_dev->channels = ad2s1200_channels;
 133         indio_dev->num_channels = ARRAY_SIZE(ad2s1200_channels);
 134         indio_dev->name = spi_get_device_id(spi)->name;
 135
 136         ret = devm_iio_device_register(&spi->dev, indio_dev);
 137         if (ret)
 138                 return ret;
 139
 140         spi->max_speed_hz = AD2S1200_HZ;
 141         spi->mode = SPI_MODE_3;
 142         spi_setup(spi);
 143
 144         return 0;
 145 }
 146
 147 static const struct spi_device_id ad2s1200_id[] = {
 148         { "ad2s1200" },
 149         { "ad2s1205" },
 150         {}
 151 };
 152 MODULE_DEVICE_TABLE(spi, ad2s1200_id);
 153
 154 static struct spi_driver ad2s1200_driver = {
 155         .driver = {
 156                 .name = DRV_NAME,
 157                 .owner = THIS_MODULE,
 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");