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