drivers/iio/dac/ad8801.c

   1 /*
   2  * IIO DAC driver for Analog Devices AD8801 DAC
   3  *
   4  * Copyright (C) 2016 Gwenhael Goavec-Merou
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License, version 2, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This program is distributed in the hope that it will be useful, but
  10  * WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  12  * General Public License for more details.
  13  *
  14  */
  15
  16 #include <linux/iio/iio.h>
  17 #include <linux/module.h>
  18 #include <linux/regulator/consumer.h>
  19 #include <linux/spi/spi.h>
  20 #include <linux/sysfs.h>
  21
  22 #define AD8801_CFG_ADDR_OFFSET 8
  23
  24 enum ad8801_device_ids {
  25         ID_AD8801,
  26         ID_AD8803,
  27 };
  28
  29 struct ad8801_state {
  30         struct spi_device *spi;
  31         unsigned char dac_cache[8]; /* Value write on each channel */
  32         unsigned int vrefh_mv;
  33         unsigned int vrefl_mv;
  34         struct regulator *vrefh_reg;
  35         struct regulator *vrefl_reg;
  36
  37         __be16 data ____cacheline_aligned;
  38 };
  39
  40 static int ad8801_spi_write(struct ad8801_state *state,
  41         u8 channel, unsigned char value)
  42 {
  43         state->data = cpu_to_be16((channel << AD8801_CFG_ADDR_OFFSET) | value);
  44         return spi_write(state->spi, &state->data, sizeof(state->data));
  45 }
  46
  47 static int ad8801_write_raw(struct iio_dev *indio_dev,
  48         struct iio_chan_spec const *chan, int val, int val2, long mask)
  49 {
  50         struct ad8801_state *state = iio_priv(indio_dev);
  51         int ret;
  52
  53         switch (mask) {
  54         case IIO_CHAN_INFO_RAW:
  55                 if (val >= 256 || val < 0)
  56                         return -EINVAL;
  57
  58                 ret = ad8801_spi_write(state, chan->channel, val);
  59                 if (ret == 0)
  60                         state->dac_cache[chan->channel] = val;
  61                 break;
  62         default:
  63                 ret = -EINVAL;
  64         }
  65
  66         return ret;
  67 }
  68
  69 static int ad8801_read_raw(struct iio_dev *indio_dev,
  70         struct iio_chan_spec const *chan, int *val, int *val2, long info)
  71 {
  72         struct ad8801_state *state = iio_priv(indio_dev);
  73
  74         switch (info) {
  75         case IIO_CHAN_INFO_RAW:
  76                 *val = state->dac_cache[chan->channel];
  77                 return IIO_VAL_INT;
  78         case IIO_CHAN_INFO_SCALE:
  79                 *val = state->vrefh_mv - state->vrefl_mv;
  80                 *val2 = 8;
  81                 return IIO_VAL_FRACTIONAL_LOG2;
  82         case IIO_CHAN_INFO_OFFSET:
  83                 *val = state->vrefl_mv;
  84                 return IIO_VAL_INT;
  85         default:
  86                 return -EINVAL;
  87         }
  88
  89         return -EINVAL;
  90 }
  91
  92 static const struct iio_info ad8801_info = {
  93         .read_raw = ad8801_read_raw,
  94         .write_raw = ad8801_write_raw,
  95 };
  96
  97 #define AD8801_CHANNEL(chan) {          \
  98         .type = IIO_VOLTAGE,                    \
  99         .indexed = 1,                           \
 100         .output = 1,                            \
 101         .channel = chan,                        \
 102         .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
 103         .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE) |  \
 104                 BIT(IIO_CHAN_INFO_OFFSET), \
 105 }
 106
 107 static const struct iio_chan_spec ad8801_channels[] = {
 108         AD8801_CHANNEL(0),
 109         AD8801_CHANNEL(1),
 110         AD8801_CHANNEL(2),
 111         AD8801_CHANNEL(3),
 112         AD8801_CHANNEL(4),
 113         AD8801_CHANNEL(5),
 114         AD8801_CHANNEL(6),
 115         AD8801_CHANNEL(7),
 116 };
 117
 118 static int ad8801_probe(struct spi_device *spi)
 119 {
 120         struct iio_dev *indio_dev;
 121         struct ad8801_state *state;
 122         const struct spi_device_id *id;
 123         int ret;
 124
 125         indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*state));
 126         if (indio_dev == NULL)
 127                 return -ENOMEM;
 128
 129         state = iio_priv(indio_dev);
 130         state->spi = spi;
 131         id = spi_get_device_id(spi);
 132
 133         state->vrefh_reg = devm_regulator_get(&spi->dev, "vrefh");
 134         if (IS_ERR(state->vrefh_reg)) {
 135                 dev_err(&spi->dev, "Vrefh regulator not specified\n");
 136                 return PTR_ERR(state->vrefh_reg);
 137         }
 138
 139         ret = regulator_enable(state->vrefh_reg);
 140         if (ret) {
 141                 dev_err(&spi->dev, "Failed to enable vrefh regulator: %d\n",
 142                                 ret);
 143                 return ret;
 144         }
 145
 146         ret = regulator_get_voltage(state->vrefh_reg);
 147         if (ret < 0) {
 148                 dev_err(&spi->dev, "Failed to read vrefh regulator: %d\n",
 149                                 ret);
 150                 goto error_disable_vrefh_reg;
 151         }
 152         state->vrefh_mv = ret / 1000;
 153
 154         if (id->driver_data == ID_AD8803) {
 155                 state->vrefl_reg = devm_regulator_get(&spi->dev, "vrefl");
 156                 if (IS_ERR(state->vrefl_reg)) {
 157                         dev_err(&spi->dev, "Vrefl regulator not specified\n");
 158                         ret = PTR_ERR(state->vrefl_reg);
 159                         goto error_disable_vrefh_reg;
 160                 }
 161
 162                 ret = regulator_enable(state->vrefl_reg);
 163                 if (ret) {
 164                         dev_err(&spi->dev, "Failed to enable vrefl regulator: %d\n",
 165                                         ret);
 166                         goto error_disable_vrefh_reg;
 167                 }
 168
 169                 ret = regulator_get_voltage(state->vrefl_reg);
 170                 if (ret < 0) {
 171                         dev_err(&spi->dev, "Failed to read vrefl regulator: %d\n",
 172                                         ret);
 173                         goto error_disable_vrefl_reg;
 174                 }
 175                 state->vrefl_mv = ret / 1000;
 176         } else {
 177                 state->vrefl_mv = 0;
 178                 state->vrefl_reg = NULL;
 179         }
 180
 181         spi_set_drvdata(spi, indio_dev);
 182         indio_dev->dev.parent = &spi->dev;
 183         indio_dev->info = &ad8801_info;
 184         indio_dev->modes = INDIO_DIRECT_MODE;
 185         indio_dev->channels = ad8801_channels;
 186         indio_dev->num_channels = ARRAY_SIZE(ad8801_channels);
 187         indio_dev->name = id->name;
 188
 189         ret = iio_device_register(indio_dev);
 190         if (ret) {
 191                 dev_err(&spi->dev, "Failed to register iio device: %d\n",
 192                                 ret);
 193                 goto error_disable_vrefl_reg;
 194         }
 195
 196         return 0;
 197
 198 error_disable_vrefl_reg:
 199         if (state->vrefl_reg)
 200                 regulator_disable(state->vrefl_reg);
 201 error_disable_vrefh_reg:
 202         regulator_disable(state->vrefh_reg);
 203         return ret;
 204 }
 205
 206 static int ad8801_remove(struct spi_device *spi)
 207 {
 208         struct iio_dev *indio_dev = spi_get_drvdata(spi);
 209         struct ad8801_state *state = iio_priv(indio_dev);
 210
 211         iio_device_unregister(indio_dev);
 212         if (state->vrefl_reg)
 213                 regulator_disable(state->vrefl_reg);
 214         regulator_disable(state->vrefh_reg);
 215
 216         return 0;
 217 }
 218
 219 static const struct spi_device_id ad8801_ids[] = {
 220         {"ad8801", ID_AD8801},
 221         {"ad8803", ID_AD8803},
 222         {}
 223 };
 224 MODULE_DEVICE_TABLE(spi, ad8801_ids);
 225
 226 static struct spi_driver ad8801_driver = {
 227         .driver = {
 228                 .name   = "ad8801",
 229         },
 230         .probe          = ad8801_probe,
 231         .remove         = ad8801_remove,
 232         .id_table       = ad8801_ids,
 233 };
 234 module_spi_driver(ad8801_driver);
 235
 236 MODULE_AUTHOR("Gwenhael Goavec-Merou <gwenhael.goavec-merou@trabucayre.com>");
 237 MODULE_DESCRIPTION("Analog Devices AD8801/AD8803 DAC");
 238 MODULE_LICENSE("GPL v2");