drivers/iio/adc/ti-adc128s052.c

   1 /*
   2  * Copyright (C) 2014 Angelo Compagnucci <angelo.compagnucci@gmail.com>
   3  *
   4  * Driver for Texas Instruments' ADC128S052 ADC chip.
   5  * Datasheet can be found here:
   6  * http://www.ti.com/lit/ds/symlink/adc128s052.pdf
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License version 2 as
  10  * published by the Free Software Foundation.
  11  */
  12
  13 #include <linux/err.h>
  14 #include <linux/spi/spi.h>
  15 #include <linux/module.h>
  16 #include <linux/iio/iio.h>
  17 #include <linux/regulator/consumer.h>
  18
  19 struct adc128 {
  20         struct spi_device *spi;
  21
  22         struct regulator *reg;
  23         struct mutex lock;
  24
  25         u8 buffer[2] ____cacheline_aligned;
  26 };
  27
  28 static int adc128_adc_conversion(struct adc128 *adc, u8 channel)
  29 {
  30         int ret;
  31
  32         mutex_lock(&adc->lock);
  33
  34         adc->buffer[0] = channel << 3;
  35         adc->buffer[1] = 0;
  36
  37         ret = spi_write(adc->spi, &adc->buffer, 2);
  38         if (ret < 0) {
  39                 mutex_unlock(&adc->lock);
  40                 return ret;
  41         }
  42
  43         ret = spi_read(adc->spi, &adc->buffer, 2);
  44
  45         mutex_unlock(&adc->lock);
  46
  47         if (ret < 0)
  48                 return ret;
  49
  50         return ((adc->buffer[0] << 8 | adc->buffer[1]) & 0xFFF);
  51 }
  52
  53 static int adc128_read_raw(struct iio_dev *indio_dev,
  54                            struct iio_chan_spec const *channel, int *val,
  55                            int *val2, long mask)
  56 {
  57         struct adc128 *adc = iio_priv(indio_dev);
  58         int ret;
  59
  60         switch (mask) {
  61         case IIO_CHAN_INFO_RAW:
  62
  63                 ret = adc128_adc_conversion(adc, channel->channel);
  64                 if (ret < 0)
  65                         return ret;
  66
  67                 *val = ret;
  68                 return IIO_VAL_INT;
  69
  70         case IIO_CHAN_INFO_SCALE:
  71
  72                 ret = regulator_get_voltage(adc->reg);
  73                 if (ret < 0)
  74                         return ret;
  75
  76                 *val = ret / 1000;
  77                 *val2 = 12;
  78                 return IIO_VAL_FRACTIONAL_LOG2;
  79
  80         default:
  81                 return -EINVAL;
  82         }
  83
  84 }
  85
  86 #define ADC128_VOLTAGE_CHANNEL(num)     \
  87         { \
  88                 .type = IIO_VOLTAGE, \
  89                 .indexed = 1, \
  90                 .channel = (num), \
  91                 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
  92                 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE) \
  93         }
  94
  95 static const struct iio_chan_spec adc128_channels[] = {
  96         ADC128_VOLTAGE_CHANNEL(0),
  97         ADC128_VOLTAGE_CHANNEL(1),
  98         ADC128_VOLTAGE_CHANNEL(2),
  99         ADC128_VOLTAGE_CHANNEL(3),
 100         ADC128_VOLTAGE_CHANNEL(4),
 101         ADC128_VOLTAGE_CHANNEL(5),
 102         ADC128_VOLTAGE_CHANNEL(6),
 103         ADC128_VOLTAGE_CHANNEL(7),
 104 };
 105
 106 static const struct iio_info adc128_info = {
 107         .read_raw = adc128_read_raw,
 108         .driver_module = THIS_MODULE,
 109 };
 110
 111 static int adc128_probe(struct spi_device *spi)
 112 {
 113         struct iio_dev *indio_dev;
 114         struct adc128 *adc;
 115         int ret;
 116
 117         indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*adc));
 118         if (!indio_dev)
 119                 return -ENOMEM;
 120
 121         adc = iio_priv(indio_dev);
 122         adc->spi = spi;
 123
 124         spi_set_drvdata(spi, indio_dev);
 125
 126         indio_dev->dev.parent = &spi->dev;
 127         indio_dev->name = spi_get_device_id(spi)->name;
 128         indio_dev->modes = INDIO_DIRECT_MODE;
 129         indio_dev->info = &adc128_info;
 130
 131         indio_dev->channels = adc128_channels;
 132         indio_dev->num_channels = ARRAY_SIZE(adc128_channels);
 133
 134         adc->reg = devm_regulator_get(&spi->dev, "vref");
 135         if (IS_ERR(adc->reg))
 136                 return PTR_ERR(adc->reg);
 137
 138         ret = regulator_enable(adc->reg);
 139         if (ret < 0)
 140                 return ret;
 141
 142         mutex_init(&adc->lock);
 143
 144         ret = iio_device_register(indio_dev);
 145
 146         return ret;
 147 }
 148
 149 static int adc128_remove(struct spi_device *spi)
 150 {
 151         struct iio_dev *indio_dev = spi_get_drvdata(spi);
 152         struct adc128 *adc = iio_priv(indio_dev);
 153
 154         iio_device_unregister(indio_dev);
 155         regulator_disable(adc->reg);
 156
 157         return 0;
 158 }
 159
 160 static const struct spi_device_id adc128_id[] = {
 161         { "adc128s052", 0},
 162         { }
 163 };
 164 MODULE_DEVICE_TABLE(spi, adc128_id);
 165
 166 static struct spi_driver adc128_driver = {
 167         .driver = {
 168                 .name = "adc128s052",
 169                 .owner = THIS_MODULE,
 170         },
 171         .probe = adc128_probe,
 172         .remove = adc128_remove,
 173         .id_table = adc128_id,
 174 };
 175 module_spi_driver(adc128_driver);
 176
 177 MODULE_AUTHOR("Angelo Compagnucci <angelo.compagnucci@gmail.com>");
 178 MODULE_DESCRIPTION("Texas Instruments ADC128S052");
 179 MODULE_LICENSE("GPL v2");