drivers/iio/dac/ad7303.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * AD7303 Digital to analog converters driver
   4  *
   5  * Copyright 2013 Analog Devices Inc.
   6  */
   7
   8 #include <linux/err.h>
   9 #include <linux/module.h>
  10 #include <linux/kernel.h>
  11 #include <linux/spi/spi.h>
  12 #include <linux/slab.h>
  13 #include <linux/sysfs.h>
  14 #include <linux/regulator/consumer.h>
  15
  16 #include <linux/iio/iio.h>
  17 #include <linux/iio/sysfs.h>
  18
  19 #include <linux/platform_data/ad7303.h>
  20
  21 #define AD7303_CFG_EXTERNAL_VREF BIT(15)
  22 #define AD7303_CFG_POWER_DOWN(ch) BIT(11 + (ch))
  23 #define AD7303_CFG_ADDR_OFFSET  10
  24
  25 #define AD7303_CMD_UPDATE_DAC   (0x3 << 8)
  26
  27 /**
  28  * struct ad7303_state - driver instance specific data
  29  * @spi:                the device for this driver instance
  30  * @config:             cached config register value
  31  * @dac_cache:          current DAC raw value (chip does not support readback)
  32  * @data:               spi transfer buffer
  33  */
  34
  35 struct ad7303_state {
  36         struct spi_device *spi;
  37         uint16_t config;
  38         uint8_t dac_cache[2];
  39
  40         struct regulator *vdd_reg;
  41         struct regulator *vref_reg;
  42
  43         struct mutex lock;
  44         /*
  45          * DMA (thus cache coherency maintenance) requires the
  46          * transfer buffers to live in their own cache lines.
  47          */
  48         __be16 data ____cacheline_aligned;
  49 };
  50
  51 static int ad7303_write(struct ad7303_state *st, unsigned int chan,
  52         uint8_t val)
  53 {
  54         st->data = cpu_to_be16(AD7303_CMD_UPDATE_DAC |
  55                 (chan << AD7303_CFG_ADDR_OFFSET) |
  56                 st->config | val);
  57
  58         return spi_write(st->spi, &st->data, sizeof(st->data));
  59 }
  60
  61 static ssize_t ad7303_read_dac_powerdown(struct iio_dev *indio_dev,
  62         uintptr_t private, const struct iio_chan_spec *chan, char *buf)
  63 {
  64         struct ad7303_state *st = iio_priv(indio_dev);
  65
  66         return sprintf(buf, "%d\n", (bool)(st->config &
  67                 AD7303_CFG_POWER_DOWN(chan->channel)));
  68 }
  69
  70 static ssize_t ad7303_write_dac_powerdown(struct iio_dev *indio_dev,
  71          uintptr_t private, const struct iio_chan_spec *chan, const char *buf,
  72          size_t len)
  73 {
  74         struct ad7303_state *st = iio_priv(indio_dev);
  75         bool pwr_down;
  76         int ret;
  77
  78         ret = strtobool(buf, &pwr_down);
  79         if (ret)
  80                 return ret;
  81
  82         mutex_lock(&st->lock);
  83
  84         if (pwr_down)
  85                 st->config |= AD7303_CFG_POWER_DOWN(chan->channel);
  86         else
  87                 st->config &= ~AD7303_CFG_POWER_DOWN(chan->channel);
  88
  89         /* There is no noop cmd which allows us to only update the powerdown
  90          * mode, so just write one of the DAC channels again */
  91         ad7303_write(st, chan->channel, st->dac_cache[chan->channel]);
  92
  93         mutex_unlock(&st->lock);
  94         return len;
  95 }
  96
  97 static int ad7303_get_vref(struct ad7303_state *st,
  98         struct iio_chan_spec const *chan)
  99 {
 100         int ret;
 101
 102         if (st->config & AD7303_CFG_EXTERNAL_VREF)
 103                 return regulator_get_voltage(st->vref_reg);
 104
 105         ret = regulator_get_voltage(st->vdd_reg);
 106         if (ret < 0)
 107                 return ret;
 108         return ret / 2;
 109 }
 110
 111 static int ad7303_read_raw(struct iio_dev *indio_dev,
 112         struct iio_chan_spec const *chan, int *val, int *val2, long info)
 113 {
 114         struct ad7303_state *st = iio_priv(indio_dev);
 115         int vref_uv;
 116
 117         switch (info) {
 118         case IIO_CHAN_INFO_RAW:
 119                 mutex_lock(&st->lock);
 120                 *val = st->dac_cache[chan->channel];
 121                 mutex_unlock(&st->lock);
 122                 return IIO_VAL_INT;
 123         case IIO_CHAN_INFO_SCALE:
 124                 vref_uv = ad7303_get_vref(st, chan);
 125                 if (vref_uv < 0)
 126                         return vref_uv;
 127
 128                 *val = 2 * vref_uv / 1000;
 129                 *val2 = chan->scan_type.realbits;
 130
 131                 return IIO_VAL_FRACTIONAL_LOG2;
 132         default:
 133                 break;
 134         }
 135         return -EINVAL;
 136 }
 137
 138 static int ad7303_write_raw(struct iio_dev *indio_dev,
 139         struct iio_chan_spec const *chan, int val, int val2, long mask)
 140 {
 141         struct ad7303_state *st = iio_priv(indio_dev);
 142         int ret;
 143
 144         switch (mask) {
 145         case IIO_CHAN_INFO_RAW:
 146                 if (val >= (1 << chan->scan_type.realbits) || val < 0)
 147                         return -EINVAL;
 148
 149                 mutex_lock(&st->lock);
 150                 ret = ad7303_write(st, chan->address, val);
 151                 if (ret == 0)
 152                         st->dac_cache[chan->channel] = val;
 153                 mutex_unlock(&st->lock);
 154                 break;
 155         default:
 156                 ret = -EINVAL;
 157         }
 158
 159         return ret;
 160 }
 161
 162 static const struct iio_info ad7303_info = {
 163         .read_raw = ad7303_read_raw,
 164         .write_raw = ad7303_write_raw,
 165 };
 166
 167 static const struct iio_chan_spec_ext_info ad7303_ext_info[] = {
 168         {
 169                 .name = "powerdown",
 170                 .read = ad7303_read_dac_powerdown,
 171                 .write = ad7303_write_dac_powerdown,
 172                 .shared = IIO_SEPARATE,
 173         },
 174         { },
 175 };
 176
 177 #define AD7303_CHANNEL(chan) {                                  \
 178         .type = IIO_VOLTAGE,                                    \
 179         .indexed = 1,                                           \
 180         .output = 1,                                            \
 181         .channel = (chan),                                      \
 182         .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),           \
 183         .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),   \
 184         .address = (chan),                                      \
 185         .scan_type = {                                          \
 186                 .sign = 'u',                                    \
 187                 .realbits = 8,                                  \
 188                 .storagebits = 8,                               \
 189                 .shift = 0,                                     \
 190         },                                                      \
 191         .ext_info = ad7303_ext_info,                            \
 192 }
 193
 194 static const struct iio_chan_spec ad7303_channels[] = {
 195         AD7303_CHANNEL(0),
 196         AD7303_CHANNEL(1),
 197 };
 198
 199 static int ad7303_probe(struct spi_device *spi)
 200 {
 201         const struct spi_device_id *id = spi_get_device_id(spi);
 202         struct iio_dev *indio_dev;
 203         struct ad7303_state *st;
 204         int ret;
 205
 206         indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
 207         if (indio_dev == NULL)
 208                 return -ENOMEM;
 209
 210         st = iio_priv(indio_dev);
 211         spi_set_drvdata(spi, indio_dev);
 212
 213         st->spi = spi;
 214
 215         mutex_init(&st->lock);
 216
 217         st->vdd_reg = devm_regulator_get(&spi->dev, "Vdd");
 218         if (IS_ERR(st->vdd_reg))
 219                 return PTR_ERR(st->vdd_reg);
 220
 221         ret = regulator_enable(st->vdd_reg);
 222         if (ret)
 223                 return ret;
 224
 225         st->vref_reg = devm_regulator_get_optional(&spi->dev, "REF");
 226         if (IS_ERR(st->vref_reg)) {
 227                 ret = PTR_ERR(st->vref_reg);
 228                 if (ret != -ENODEV)
 229                         goto err_disable_vdd_reg;
 230                 st->vref_reg = NULL;
 231         }
 232
 233         if (st->vref_reg) {
 234                 ret = regulator_enable(st->vref_reg);
 235                 if (ret)
 236                         goto err_disable_vdd_reg;
 237
 238                 st->config |= AD7303_CFG_EXTERNAL_VREF;
 239         }
 240
 241         indio_dev->dev.parent = &spi->dev;
 242         indio_dev->name = id->name;
 243         indio_dev->info = &ad7303_info;
 244         indio_dev->modes = INDIO_DIRECT_MODE;
 245         indio_dev->channels = ad7303_channels;
 246         indio_dev->num_channels = ARRAY_SIZE(ad7303_channels);
 247
 248         ret = iio_device_register(indio_dev);
 249         if (ret)
 250                 goto err_disable_vref_reg;
 251
 252         return 0;
 253
 254 err_disable_vref_reg:
 255         if (st->vref_reg)
 256                 regulator_disable(st->vref_reg);
 257 err_disable_vdd_reg:
 258         regulator_disable(st->vdd_reg);
 259         return ret;
 260 }
 261
 262 static int ad7303_remove(struct spi_device *spi)
 263 {
 264         struct iio_dev *indio_dev = spi_get_drvdata(spi);
 265         struct ad7303_state *st = iio_priv(indio_dev);
 266
 267         iio_device_unregister(indio_dev);
 268
 269         if (st->vref_reg)
 270                 regulator_disable(st->vref_reg);
 271         regulator_disable(st->vdd_reg);
 272
 273         return 0;
 274 }
 275
 276 static const struct of_device_id ad7303_spi_of_match[] = {
 277         { .compatible = "adi,ad7303", },
 278         { /* sentinel */ },
 279 };
 280 MODULE_DEVICE_TABLE(of, ad7303_spi_of_match);
 281
 282 static const struct spi_device_id ad7303_spi_ids[] = {
 283         { "ad7303", 0 },
 284         {}
 285 };
 286 MODULE_DEVICE_TABLE(spi, ad7303_spi_ids);
 287
 288 static struct spi_driver ad7303_driver = {
 289         .driver = {
 290                 .name = "ad7303",
 291                 .of_match_table = of_match_ptr(ad7303_spi_of_match),
 292         },
 293         .probe = ad7303_probe,
 294         .remove = ad7303_remove,
 295         .id_table = ad7303_spi_ids,
 296 };
 297 module_spi_driver(ad7303_driver);
 298
 299 MODULE_AUTHOR("Lars-Peter Clausen <lars@metafoo.de>");
 300 MODULE_DESCRIPTION("Analog Devices AD7303 DAC driver");
 301 MODULE_LICENSE("GPL v2");