drivers/iio/adc/ad7292.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Analog Devices AD7292 SPI ADC driver
   4  *
   5  * Copyright 2019 Analog Devices Inc.
   6  */
   7
   8 #include <linux/bitfield.h>
   9 #include <linux/device.h>
  10 #include <linux/module.h>
  11 #include <linux/regulator/consumer.h>
  12 #include <linux/spi/spi.h>
  13
  14 #include <linux/iio/iio.h>
  15
  16 #define ADI_VENDOR_ID 0x0018
  17
  18 /* AD7292 registers definition */
  19 #define AD7292_REG_VENDOR_ID            0x00
  20 #define AD7292_REG_CONF_BANK            0x05
  21 #define AD7292_REG_CONV_COMM            0x0E
  22 #define AD7292_REG_ADC_CH(x)            (0x10 + (x))
  23
  24 /* AD7292 configuration bank subregisters definition */
  25 #define AD7292_BANK_REG_VIN_RNG0        0x10
  26 #define AD7292_BANK_REG_VIN_RNG1        0x11
  27 #define AD7292_BANK_REG_SAMP_MODE       0x12
  28
  29 #define AD7292_RD_FLAG_MSK(x)           (BIT(7) | ((x) & 0x3F))
  30
  31 /* AD7292_REG_ADC_CONVERSION */
  32 #define AD7292_ADC_DATA_MASK            GENMASK(15, 6)
  33 #define AD7292_ADC_DATA(x)              FIELD_GET(AD7292_ADC_DATA_MASK, x)
  34
  35 /* AD7292_CHANNEL_SAMPLING_MODE */
  36 #define AD7292_CH_SAMP_MODE(reg, ch)    (((reg) >> 8) & BIT(ch))
  37
  38 /* AD7292_CHANNEL_VIN_RANGE */
  39 #define AD7292_CH_VIN_RANGE(reg, ch)    ((reg) & BIT(ch))
  40
  41 #define AD7292_VOLTAGE_CHAN(_chan)                                      \
  42 {                                                                       \
  43         .type = IIO_VOLTAGE,                                            \
  44         .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |                  \
  45                               BIT(IIO_CHAN_INFO_SCALE),                 \
  46         .indexed = 1,                                                   \
  47         .channel = _chan,                                               \
  48 }
  49
  50 static const struct iio_chan_spec ad7292_channels[] = {
  51         AD7292_VOLTAGE_CHAN(0),
  52         AD7292_VOLTAGE_CHAN(1),
  53         AD7292_VOLTAGE_CHAN(2),
  54         AD7292_VOLTAGE_CHAN(3),
  55         AD7292_VOLTAGE_CHAN(4),
  56         AD7292_VOLTAGE_CHAN(5),
  57         AD7292_VOLTAGE_CHAN(6),
  58         AD7292_VOLTAGE_CHAN(7)
  59 };
  60
  61 static const struct iio_chan_spec ad7292_channels_diff[] = {
  62         {
  63                 .type = IIO_VOLTAGE,
  64                 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
  65                 .indexed = 1,
  66                 .differential = 1,
  67                 .channel = 0,
  68                 .channel2 = 1,
  69         },
  70         AD7292_VOLTAGE_CHAN(2),
  71         AD7292_VOLTAGE_CHAN(3),
  72         AD7292_VOLTAGE_CHAN(4),
  73         AD7292_VOLTAGE_CHAN(5),
  74         AD7292_VOLTAGE_CHAN(6),
  75         AD7292_VOLTAGE_CHAN(7)
  76 };
  77
  78 struct ad7292_state {
  79         struct spi_device *spi;
  80         struct regulator *reg;
  81         unsigned short vref_mv;
  82
  83         __be16 d16 ____cacheline_aligned;
  84         u8 d8[2];
  85 };
  86
  87 static int ad7292_spi_reg_read(struct ad7292_state *st, unsigned int addr)
  88 {
  89         int ret;
  90
  91         st->d8[0] = AD7292_RD_FLAG_MSK(addr);
  92
  93         ret = spi_write_then_read(st->spi, st->d8, 1, &st->d16, 2);
  94         if (ret < 0)
  95                 return ret;
  96
  97         return be16_to_cpu(st->d16);
  98 }
  99
 100 static int ad7292_spi_subreg_read(struct ad7292_state *st, unsigned int addr,
 101                                   unsigned int sub_addr, unsigned int len)
 102 {
 103         unsigned int shift = 16 - (8 * len);
 104         int ret;
 105
 106         st->d8[0] = AD7292_RD_FLAG_MSK(addr);
 107         st->d8[1] = sub_addr;
 108
 109         ret = spi_write_then_read(st->spi, st->d8, 2, &st->d16, len);
 110         if (ret < 0)
 111                 return ret;
 112
 113         return (be16_to_cpu(st->d16) >> shift);
 114 }
 115
 116 static int ad7292_single_conversion(struct ad7292_state *st,
 117                                     unsigned int chan_addr)
 118 {
 119         int ret;
 120
 121         struct spi_transfer t[] = {
 122                 {
 123                         .tx_buf = &st->d8,
 124                         .len = 4,
 125                         .delay_usecs = 6,
 126                 }, {
 127                         .rx_buf = &st->d16,
 128                         .len = 2,
 129                 },
 130         };
 131
 132         st->d8[0] = chan_addr;
 133         st->d8[1] = AD7292_RD_FLAG_MSK(AD7292_REG_CONV_COMM);
 134
 135         ret = spi_sync_transfer(st->spi, t, ARRAY_SIZE(t));
 136
 137         if (ret < 0)
 138                 return ret;
 139
 140         return be16_to_cpu(st->d16);
 141 }
 142
 143 static int ad7292_vin_range_multiplier(struct ad7292_state *st, int channel)
 144 {
 145         int samp_mode, range0, range1, factor = 1;
 146
 147         /*
 148          * Every AD7292 ADC channel may have its input range adjusted according
 149          * to the settings at the ADC sampling mode and VIN range subregisters.
 150          * For a given channel, the minimum input range is equal to Vref, and it
 151          * may be increased by a multiplier factor of 2 or 4 according to the
 152          * following rule:
 153          * If channel is being sampled with respect to AGND:
 154          *      factor = 4 if VIN range0 and VIN range1 equal 0
 155          *      factor = 2 if only one of VIN ranges equal 1
 156          *      factor = 1 if both VIN range0 and VIN range1 equal 1
 157          * If channel is being sampled with respect to AVDD:
 158          *      factor = 4 if VIN range0 and VIN range1 equal 0
 159          *      Behavior is undefined if any of VIN range doesn't equal 0
 160          */
 161
 162         samp_mode = ad7292_spi_subreg_read(st, AD7292_REG_CONF_BANK,
 163                                            AD7292_BANK_REG_SAMP_MODE, 2);
 164
 165         if (samp_mode < 0)
 166                 return samp_mode;
 167
 168         range0 = ad7292_spi_subreg_read(st, AD7292_REG_CONF_BANK,
 169                                         AD7292_BANK_REG_VIN_RNG0, 2);
 170
 171         if (range0 < 0)
 172                 return range0;
 173
 174         range1 = ad7292_spi_subreg_read(st, AD7292_REG_CONF_BANK,
 175                                         AD7292_BANK_REG_VIN_RNG1, 2);
 176
 177         if (range1 < 0)
 178                 return range1;
 179
 180         if (AD7292_CH_SAMP_MODE(samp_mode, channel)) {
 181                 /* Sampling with respect to AGND */
 182                 if (!AD7292_CH_VIN_RANGE(range0, channel))
 183                         factor *= 2;
 184
 185                 if (!AD7292_CH_VIN_RANGE(range1, channel))
 186                         factor *= 2;
 187
 188         } else {
 189                 /* Sampling with respect to AVDD */
 190                 if (AD7292_CH_VIN_RANGE(range0, channel) ||
 191                     AD7292_CH_VIN_RANGE(range1, channel))
 192                         return -EPERM;
 193
 194                 factor = 4;
 195         }
 196
 197         return factor;
 198 }
 199
 200 static int ad7292_read_raw(struct iio_dev *indio_dev,
 201                            const struct iio_chan_spec *chan,
 202                            int *val, int *val2, long info)
 203 {
 204         struct ad7292_state *st = iio_priv(indio_dev);
 205         unsigned int ch_addr;
 206         int ret;
 207
 208         switch (info) {
 209         case IIO_CHAN_INFO_RAW:
 210                 ch_addr = AD7292_REG_ADC_CH(chan->channel);
 211                 ret = ad7292_single_conversion(st, ch_addr);
 212                 if (ret < 0)
 213                         return ret;
 214
 215                 *val = AD7292_ADC_DATA(ret);
 216
 217                 return IIO_VAL_INT;
 218         case IIO_CHAN_INFO_SCALE:
 219                 /*
 220                  * To convert a raw value to standard units, the IIO defines
 221                  * this formula: Scaled value = (raw + offset) * scale.
 222                  * For the scale to be a correct multiplier for (raw + offset),
 223                  * it must be calculated as the input range divided by the
 224                  * number of possible distinct input values. Given the ADC data
 225                  * is 10 bit long, it may assume 2^10 distinct values.
 226                  * Hence, scale = range / 2^10. The IIO_VAL_FRACTIONAL_LOG2
 227                  * return type indicates to the IIO API to divide *val by 2 to
 228                  * the power of *val2 when returning from read_raw.
 229                  */
 230
 231                 ret = ad7292_vin_range_multiplier(st, chan->channel);
 232                 if (ret < 0)
 233                         return ret;
 234
 235                 *val = st->vref_mv * ret;
 236                 *val2 = 10;
 237                 return IIO_VAL_FRACTIONAL_LOG2;
 238         default:
 239                 break;
 240         }
 241         return -EINVAL;
 242 }
 243
 244 static const struct iio_info ad7292_info = {
 245         .read_raw = ad7292_read_raw,
 246 };
 247
 248 static void ad7292_regulator_disable(void *data)
 249 {
 250         struct ad7292_state *st = data;
 251
 252         regulator_disable(st->reg);
 253 }
 254
 255 static int ad7292_probe(struct spi_device *spi)
 256 {
 257         struct ad7292_state *st;
 258         struct iio_dev *indio_dev;
 259         struct device_node *child;
 260         bool diff_channels = 0;
 261         int ret;
 262
 263         indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
 264         if (!indio_dev)
 265                 return -ENOMEM;
 266
 267         st = iio_priv(indio_dev);
 268         st->spi = spi;
 269
 270         ret = ad7292_spi_reg_read(st, AD7292_REG_VENDOR_ID);
 271         if (ret != ADI_VENDOR_ID) {
 272                 dev_err(&spi->dev, "Wrong vendor id 0x%x\n", ret);
 273                 return -EINVAL;
 274         }
 275
 276         spi_set_drvdata(spi, indio_dev);
 277
 278         st->reg = devm_regulator_get_optional(&spi->dev, "vref");
 279         if (!IS_ERR(st->reg)) {
 280                 ret = regulator_enable(st->reg);
 281                 if (ret) {
 282                         dev_err(&spi->dev,
 283                                 "Failed to enable external vref supply\n");
 284                         return ret;
 285                 }
 286
 287                 ret = devm_add_action_or_reset(&spi->dev,
 288                                                ad7292_regulator_disable, st);
 289                 if (ret) {
 290                         regulator_disable(st->reg);
 291                         return ret;
 292                 }
 293
 294                 ret = regulator_get_voltage(st->reg);
 295                 if (ret < 0)
 296                         return ret;
 297
 298                 st->vref_mv = ret / 1000;
 299         } else {
 300                 /* Use the internal voltage reference. */
 301                 st->vref_mv = 1250;
 302         }
 303
 304         indio_dev->dev.parent = &spi->dev;
 305         indio_dev->name = spi_get_device_id(spi)->name;
 306         indio_dev->modes = INDIO_DIRECT_MODE;
 307         indio_dev->info = &ad7292_info;
 308
 309         for_each_available_child_of_node(spi->dev.of_node, child) {
 310                 diff_channels = of_property_read_bool(child, "diff-channels");
 311                 if (diff_channels)
 312                         break;
 313         }
 314
 315         if (diff_channels) {
 316                 indio_dev->num_channels = ARRAY_SIZE(ad7292_channels_diff);
 317                 indio_dev->channels = ad7292_channels_diff;
 318         } else {
 319                 indio_dev->num_channels = ARRAY_SIZE(ad7292_channels);
 320                 indio_dev->channels = ad7292_channels;
 321         }
 322
 323         return devm_iio_device_register(&spi->dev, indio_dev);
 324 }
 325
 326 static const struct spi_device_id ad7292_id_table[] = {
 327         { "ad7292", 0 },
 328         {}
 329 };
 330 MODULE_DEVICE_TABLE(spi, ad7292_id_table);
 331
 332 static const struct of_device_id ad7292_of_match[] = {
 333         { .compatible = "adi,ad7292" },
 334         { },
 335 };
 336 MODULE_DEVICE_TABLE(of, ad7292_of_match);
 337
 338 static struct spi_driver ad7292_driver = {
 339         .driver = {
 340                 .name = "ad7292",
 341                 .of_match_table = ad7292_of_match,
 342         },
 343         .probe = ad7292_probe,
 344         .id_table = ad7292_id_table,
 345 };
 346 module_spi_driver(ad7292_driver);
 347
 348 MODULE_AUTHOR("Marcelo Schmitt <marcelo.schmitt1@gmail.com>");
 349 MODULE_DESCRIPTION("Analog Devices AD7292 ADC driver");
 350 MODULE_LICENSE("GPL v2");