drivers/iio/dac/ad7303.c

   1 /*
   2  * AD7303 Digital to analog converters driver
   3  *
   4  * Copyright 2013 Analog Devices Inc.
   5  *
   6  * Licensed under the GPL-2.
   7  */
   8
   9 #include <linux/err.h>
  10 #include <linux/module.h>
  11 #include <linux/kernel.h>
  12 #include <linux/spi/spi.h>
  13 #include <linux/slab.h>
  14 #include <linux/sysfs.h>
  15 #include <linux/regulator/consumer.h>
  16 #include <linux/of.h>
  17
  18 #include <linux/iio/iio.h>
  19 #include <linux/iio/sysfs.h>
  20
  21 #include <linux/platform_data/ad7303.h>
  22
  23 #define AD7303_CFG_EXTERNAL_VREF BIT(15)
  24 #define AD7303_CFG_POWER_DOWN(ch) BIT(11 + (ch))
  25 #define AD7303_CFG_ADDR_OFFSET  10
  26
  27 #define AD7303_CMD_UPDATE_DAC   (0x3 << 8)
  28
  29 /**
  30  * struct ad7303_state - driver instance specific data
  31  * @spi:                the device for this driver instance
  32  * @config:             cached config register value
  33  * @dac_cache:          current DAC raw value (chip does not support readback)
  34  * @data:               spi transfer buffer
  35  */
  36
  37 struct ad7303_state {
  38         struct spi_device *spi;
  39         uint16_t config;
  40         uint8_t dac_cache[2];
  41
  42         struct regulator *vdd_reg;
  43         struct regulator *vref_reg;
  44
  45         /*
  46          * DMA (thus cache coherency maintenance) requires the
  47          * transfer buffers to live in their own cache lines.
  48          */
  49         __be16 data ____cacheline_aligned;
  50 };
  51
  52 static int ad7303_write(struct ad7303_state *st, unsigned int chan,
  53         uint8_t val)
  54 {
  55         st->data = cpu_to_be16(AD7303_CMD_UPDATE_DAC |
  56                 (chan << AD7303_CFG_ADDR_OFFSET) |
  57                 st->config | val);
  58
  59         return spi_write(st->spi, &st->data, sizeof(st->data));
  60 }
  61
  62 static ssize_t ad7303_read_dac_powerdown(struct iio_dev *indio_dev,
  63         uintptr_t private, const struct iio_chan_spec *chan, char *buf)
  64 {
  65         struct ad7303_state *st = iio_priv(indio_dev);
  66
  67         return sprintf(buf, "%d\n", (bool)(st->config &
  68                 AD7303_CFG_POWER_DOWN(chan->channel)));
  69 }
  70
  71 static ssize_t ad7303_write_dac_powerdown(struct iio_dev *indio_dev,
  72          uintptr_t private, const struct iio_chan_spec *chan, const char *buf,
  73          size_t len)
  74 {
  75         struct ad7303_state *st = iio_priv(indio_dev);
  76         bool pwr_down;
  77         int ret;
  78
  79         ret = strtobool(buf, &pwr_down);
  80         if (ret)
  81                 return ret;
  82
  83         mutex_lock(&indio_dev->mlock);
  84
  85         if (pwr_down)
  86                 st->config |= AD7303_CFG_POWER_DOWN(chan->channel);
  87         else
  88                 st->config &= ~AD7303_CFG_POWER_DOWN(chan->channel);
  89
  90         /* There is no noop cmd which allows us to only update the powerdown
  91          * mode, so just write one of the DAC channels again */
  92         ad7303_write(st, chan->channel, st->dac_cache[chan->channel]);
  93
  94         mutex_unlock(&indio_dev->mlock);
  95         return len;
  96 }
  97
  98 static int ad7303_get_vref(struct ad7303_state *st,
  99         struct iio_chan_spec const *chan)
 100 {
 101         int ret;
 102
 103         if (st->config & AD7303_CFG_EXTERNAL_VREF)
 104                 return regulator_get_voltage(st->vref_reg);
 105
 106         ret = regulator_get_voltage(st->vdd_reg);
 107         if (ret < 0)
 108                 return ret;
 109         return ret / 2;
 110 }
 111
 112 static int ad7303_read_raw(struct iio_dev *indio_dev,
 113         struct iio_chan_spec const *chan, int *val, int *val2, long info)
 114 {
 115         struct ad7303_state *st = iio_priv(indio_dev);
 116         int vref_uv;
 117
 118         switch (info) {
 119         case IIO_CHAN_INFO_RAW:
 120                 *val = st->dac_cache[chan->channel];
 121                 return IIO_VAL_INT;
 122         case IIO_CHAN_INFO_SCALE:
 123                 vref_uv = ad7303_get_vref(st, chan);
 124                 if (vref_uv < 0)
 125                         return vref_uv;
 126
 127                 *val = 2 * vref_uv / 1000;
 128                 *val2 = chan->scan_type.realbits;
 129
 130                 return IIO_VAL_FRACTIONAL_LOG2;
 131         default:
 132                 break;
 133         }
 134         return -EINVAL;
 135 }
 136
 137 static int ad7303_write_raw(struct iio_dev *indio_dev,
 138         struct iio_chan_spec const *chan, int val, int val2, long mask)
 139 {
 140         struct ad7303_state *st = iio_priv(indio_dev);
 141         int ret;
 142
 143         switch (mask) {
 144         case IIO_CHAN_INFO_RAW:
 145                 if (val >= (1 << chan->scan_type.realbits) || val < 0)
 146                         return -EINVAL;
 147
 148                 mutex_lock(&indio_dev->mlock);
 149                 ret = ad7303_write(st, chan->address, val);
 150                 if (ret == 0)
 151                         st->dac_cache[chan->channel] = val;
 152                 mutex_unlock(&indio_dev->mlock);
 153                 break;
 154         default:
 155                 ret = -EINVAL;
 156         }
 157
 158         return ret;
 159 }
 160
 161 static const struct iio_info ad7303_info = {
 162         .read_raw = ad7303_read_raw,
 163         .write_raw = ad7303_write_raw,
 164         .driver_module = THIS_MODULE,
 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         bool ext_ref;
 205         int ret;
 206
 207         indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
 208         if (indio_dev == NULL)
 209                 return -ENOMEM;
 210
 211         st = iio_priv(indio_dev);
 212         spi_set_drvdata(spi, indio_dev);
 213
 214         st->spi = spi;
 215
 216         st->vdd_reg = devm_regulator_get(&spi->dev, "Vdd");
 217         if (IS_ERR(st->vdd_reg))
 218                 return PTR_ERR(st->vdd_reg);
 219
 220         ret = regulator_enable(st->vdd_reg);
 221         if (ret)
 222                 return ret;
 223
 224         if (spi->dev.of_node) {
 225                 ext_ref = of_property_read_bool(spi->dev.of_node,
 226                                 "REF-supply");
 227         } else {
 228                 struct ad7303_platform_data *pdata = spi->dev.platform_data;
 229                 if (pdata && pdata->use_external_ref)
 230                         ext_ref = true;
 231                 else
 232                     ext_ref = false;
 233         }
 234
 235         if (ext_ref) {
 236                 st->vref_reg = devm_regulator_get(&spi->dev, "REF");
 237                 if (IS_ERR(st->vref_reg)) {
 238                         ret = PTR_ERR(st->vref_reg);
 239                         goto err_disable_vdd_reg;
 240                 }
 241
 242                 ret = regulator_enable(st->vref_reg);
 243                 if (ret)
 244                         goto err_disable_vdd_reg;
 245
 246                 st->config |= AD7303_CFG_EXTERNAL_VREF;
 247         }
 248
 249         indio_dev->dev.parent = &spi->dev;
 250         indio_dev->name = id->name;
 251         indio_dev->info = &ad7303_info;
 252         indio_dev->modes = INDIO_DIRECT_MODE;
 253         indio_dev->channels = ad7303_channels;
 254         indio_dev->num_channels = ARRAY_SIZE(ad7303_channels);
 255
 256         ret = iio_device_register(indio_dev);
 257         if (ret)
 258                 goto err_disable_vref_reg;
 259
 260         return 0;
 261
 262 err_disable_vref_reg:
 263         if (st->vref_reg)
 264                 regulator_disable(st->vref_reg);
 265 err_disable_vdd_reg:
 266         regulator_disable(st->vdd_reg);
 267         return ret;
 268 }
 269
 270 static int ad7303_remove(struct spi_device *spi)
 271 {
 272         struct iio_dev *indio_dev = spi_get_drvdata(spi);
 273         struct ad7303_state *st = iio_priv(indio_dev);
 274
 275         iio_device_unregister(indio_dev);
 276
 277         if (st->vref_reg)
 278                 regulator_disable(st->vref_reg);
 279         regulator_disable(st->vdd_reg);
 280
 281         return 0;
 282 }
 283
 284 static const struct spi_device_id ad7303_spi_ids[] = {
 285         { "ad7303", 0 },
 286         {}
 287 };
 288 MODULE_DEVICE_TABLE(spi, ad7303_spi_ids);
 289
 290 static struct spi_driver ad7303_driver = {
 291         .driver = {
 292                 .name = "ad7303",
 293                 .owner = THIS_MODULE,
 294         },
 295         .probe = ad7303_probe,
 296         .remove = ad7303_remove,
 297         .id_table = ad7303_spi_ids,
 298 };
 299 module_spi_driver(ad7303_driver);
 300
 301 MODULE_AUTHOR("Lars-Peter Clausen <lars@metafoo.de>");
 302 MODULE_DESCRIPTION("Analog Devices AD7303 DAC driver");
 303 MODULE_LICENSE("GPL v2");