drivers/iio/adc/ti-adc0832.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * ADC0831/ADC0832/ADC0834/ADC0838 8-bit ADC driver
   4  *
   5  * Copyright (c) 2016 Akinobu Mita <akinobu.mita@gmail.com>
   6  *
   7  * Datasheet: http://www.ti.com/lit/ds/symlink/adc0832-n.pdf
   8  */
   9
  10 #include <linux/module.h>
  11 #include <linux/spi/spi.h>
  12 #include <linux/iio/iio.h>
  13 #include <linux/regulator/consumer.h>
  14 #include <linux/iio/buffer.h>
  15 #include <linux/iio/trigger.h>
  16 #include <linux/iio/triggered_buffer.h>
  17 #include <linux/iio/trigger_consumer.h>
  18
  19 enum {
  20         adc0831,
  21         adc0832,
  22         adc0834,
  23         adc0838,
  24 };
  25
  26 struct adc0832 {
  27         struct spi_device *spi;
  28         struct regulator *reg;
  29         struct mutex lock;
  30         u8 mux_bits;
  31
  32         u8 tx_buf[2] ____cacheline_aligned;
  33         u8 rx_buf[2];
  34 };
  35
  36 #define ADC0832_VOLTAGE_CHANNEL(chan)                                   \
  37         {                                                               \
  38                 .type = IIO_VOLTAGE,                                    \
  39                 .indexed = 1,                                           \
  40                 .channel = chan,                                        \
  41                 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),           \
  42                 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),   \
  43                 .scan_index = chan,                                     \
  44                 .scan_type = {                                          \
  45                         .sign = 'u',                                    \
  46                         .realbits = 8,                                  \
  47                         .storagebits = 8,                               \
  48                 },                                                      \
  49         }
  50
  51 #define ADC0832_VOLTAGE_CHANNEL_DIFF(chan1, chan2, si)                  \
  52         {                                                               \
  53                 .type = IIO_VOLTAGE,                                    \
  54                 .indexed = 1,                                           \
  55                 .channel = (chan1),                                     \
  56                 .channel2 = (chan2),                                    \
  57                 .differential = 1,                                      \
  58                 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),           \
  59                 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),   \
  60                 .scan_index = si,                                       \
  61                 .scan_type = {                                          \
  62                         .sign = 'u',                                    \
  63                         .realbits = 8,                                  \
  64                         .storagebits = 8,                               \
  65                 },                                                      \
  66         }
  67
  68 static const struct iio_chan_spec adc0831_channels[] = {
  69         ADC0832_VOLTAGE_CHANNEL_DIFF(0, 1, 0),
  70         IIO_CHAN_SOFT_TIMESTAMP(1),
  71 };
  72
  73 static const struct iio_chan_spec adc0832_channels[] = {
  74         ADC0832_VOLTAGE_CHANNEL(0),
  75         ADC0832_VOLTAGE_CHANNEL(1),
  76         ADC0832_VOLTAGE_CHANNEL_DIFF(0, 1, 2),
  77         ADC0832_VOLTAGE_CHANNEL_DIFF(1, 0, 3),
  78         IIO_CHAN_SOFT_TIMESTAMP(4),
  79 };
  80
  81 static const struct iio_chan_spec adc0834_channels[] = {
  82         ADC0832_VOLTAGE_CHANNEL(0),
  83         ADC0832_VOLTAGE_CHANNEL(1),
  84         ADC0832_VOLTAGE_CHANNEL(2),
  85         ADC0832_VOLTAGE_CHANNEL(3),
  86         ADC0832_VOLTAGE_CHANNEL_DIFF(0, 1, 4),
  87         ADC0832_VOLTAGE_CHANNEL_DIFF(1, 0, 5),
  88         ADC0832_VOLTAGE_CHANNEL_DIFF(2, 3, 6),
  89         ADC0832_VOLTAGE_CHANNEL_DIFF(3, 2, 7),
  90         IIO_CHAN_SOFT_TIMESTAMP(8),
  91 };
  92
  93 static const struct iio_chan_spec adc0838_channels[] = {
  94         ADC0832_VOLTAGE_CHANNEL(0),
  95         ADC0832_VOLTAGE_CHANNEL(1),
  96         ADC0832_VOLTAGE_CHANNEL(2),
  97         ADC0832_VOLTAGE_CHANNEL(3),
  98         ADC0832_VOLTAGE_CHANNEL(4),
  99         ADC0832_VOLTAGE_CHANNEL(5),
 100         ADC0832_VOLTAGE_CHANNEL(6),
 101         ADC0832_VOLTAGE_CHANNEL(7),
 102         ADC0832_VOLTAGE_CHANNEL_DIFF(0, 1, 8),
 103         ADC0832_VOLTAGE_CHANNEL_DIFF(1, 0, 9),
 104         ADC0832_VOLTAGE_CHANNEL_DIFF(2, 3, 10),
 105         ADC0832_VOLTAGE_CHANNEL_DIFF(3, 2, 11),
 106         ADC0832_VOLTAGE_CHANNEL_DIFF(4, 5, 12),
 107         ADC0832_VOLTAGE_CHANNEL_DIFF(5, 4, 13),
 108         ADC0832_VOLTAGE_CHANNEL_DIFF(6, 7, 14),
 109         ADC0832_VOLTAGE_CHANNEL_DIFF(7, 6, 15),
 110         IIO_CHAN_SOFT_TIMESTAMP(16),
 111 };
 112
 113 static int adc0831_adc_conversion(struct adc0832 *adc)
 114 {
 115         struct spi_device *spi = adc->spi;
 116         int ret;
 117
 118         ret = spi_read(spi, &adc->rx_buf, 2);
 119         if (ret)
 120                 return ret;
 121
 122         /*
 123          * Skip TRI-STATE and a leading zero
 124          */
 125         return (adc->rx_buf[0] << 2 & 0xff) | (adc->rx_buf[1] >> 6);
 126 }
 127
 128 static int adc0832_adc_conversion(struct adc0832 *adc, int channel,
 129                                 bool differential)
 130 {
 131         struct spi_device *spi = adc->spi;
 132         struct spi_transfer xfer = {
 133                 .tx_buf = adc->tx_buf,
 134                 .rx_buf = adc->rx_buf,
 135                 .len = 2,
 136         };
 137         int ret;
 138
 139         if (!adc->mux_bits)
 140                 return adc0831_adc_conversion(adc);
 141
 142         /* start bit */
 143         adc->tx_buf[0] = 1 << (adc->mux_bits + 1);
 144         /* single-ended or differential */
 145         adc->tx_buf[0] |= differential ? 0 : (1 << adc->mux_bits);
 146         /* odd / sign */
 147         adc->tx_buf[0] |= (channel % 2) << (adc->mux_bits - 1);
 148         /* select */
 149         if (adc->mux_bits > 1)
 150                 adc->tx_buf[0] |= channel / 2;
 151
 152         /* align Data output BIT7 (MSB) to 8-bit boundary */
 153         adc->tx_buf[0] <<= 1;
 154
 155         ret = spi_sync_transfer(spi, &xfer, 1);
 156         if (ret)
 157                 return ret;
 158
 159         return adc->rx_buf[1];
 160 }
 161
 162 static int adc0832_read_raw(struct iio_dev *iio,
 163                         struct iio_chan_spec const *channel, int *value,
 164                         int *shift, long mask)
 165 {
 166         struct adc0832 *adc = iio_priv(iio);
 167
 168         switch (mask) {
 169         case IIO_CHAN_INFO_RAW:
 170                 mutex_lock(&adc->lock);
 171                 *value = adc0832_adc_conversion(adc, channel->channel,
 172                                                 channel->differential);
 173                 mutex_unlock(&adc->lock);
 174                 if (*value < 0)
 175                         return *value;
 176
 177                 return IIO_VAL_INT;
 178         case IIO_CHAN_INFO_SCALE:
 179                 *value = regulator_get_voltage(adc->reg);
 180                 if (*value < 0)
 181                         return *value;
 182
 183                 /* convert regulator output voltage to mV */
 184                 *value /= 1000;
 185                 *shift = 8;
 186
 187                 return IIO_VAL_FRACTIONAL_LOG2;
 188         }
 189
 190         return -EINVAL;
 191 }
 192
 193 static const struct iio_info adc0832_info = {
 194         .read_raw = adc0832_read_raw,
 195 };
 196
 197 static irqreturn_t adc0832_trigger_handler(int irq, void *p)
 198 {
 199         struct iio_poll_func *pf = p;
 200         struct iio_dev *indio_dev = pf->indio_dev;
 201         struct adc0832 *adc = iio_priv(indio_dev);
 202         u8 data[24] = { }; /* 16x 1 byte ADC data + 8 bytes timestamp */
 203         int scan_index;
 204         int i = 0;
 205
 206         mutex_lock(&adc->lock);
 207
 208         for_each_set_bit(scan_index, indio_dev->active_scan_mask,
 209                          indio_dev->masklength) {
 210                 const struct iio_chan_spec *scan_chan =
 211                                 &indio_dev->channels[scan_index];
 212                 int ret = adc0832_adc_conversion(adc, scan_chan->channel,
 213                                                  scan_chan->differential);
 214                 if (ret < 0) {
 215                         dev_warn(&adc->spi->dev,
 216                                  "failed to get conversion data\n");
 217                         goto out;
 218                 }
 219
 220                 data[i] = ret;
 221                 i++;
 222         }
 223         iio_push_to_buffers_with_timestamp(indio_dev, data,
 224                                            iio_get_time_ns(indio_dev));
 225 out:
 226         mutex_unlock(&adc->lock);
 227
 228         iio_trigger_notify_done(indio_dev->trig);
 229
 230         return IRQ_HANDLED;
 231 }
 232
 233 static int adc0832_probe(struct spi_device *spi)
 234 {
 235         struct iio_dev *indio_dev;
 236         struct adc0832 *adc;
 237         int ret;
 238
 239         indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*adc));
 240         if (!indio_dev)
 241                 return -ENOMEM;
 242
 243         adc = iio_priv(indio_dev);
 244         adc->spi = spi;
 245         mutex_init(&adc->lock);
 246
 247         indio_dev->name = spi_get_device_id(spi)->name;
 248         indio_dev->dev.parent = &spi->dev;
 249         indio_dev->dev.of_node = spi->dev.of_node;
 250         indio_dev->info = &adc0832_info;
 251         indio_dev->modes = INDIO_DIRECT_MODE;
 252
 253         switch (spi_get_device_id(spi)->driver_data) {
 254         case adc0831:
 255                 adc->mux_bits = 0;
 256                 indio_dev->channels = adc0831_channels;
 257                 indio_dev->num_channels = ARRAY_SIZE(adc0831_channels);
 258                 break;
 259         case adc0832:
 260                 adc->mux_bits = 1;
 261                 indio_dev->channels = adc0832_channels;
 262                 indio_dev->num_channels = ARRAY_SIZE(adc0832_channels);
 263                 break;
 264         case adc0834:
 265                 adc->mux_bits = 2;
 266                 indio_dev->channels = adc0834_channels;
 267                 indio_dev->num_channels = ARRAY_SIZE(adc0834_channels);
 268                 break;
 269         case adc0838:
 270                 adc->mux_bits = 3;
 271                 indio_dev->channels = adc0838_channels;
 272                 indio_dev->num_channels = ARRAY_SIZE(adc0838_channels);
 273                 break;
 274         default:
 275                 return -EINVAL;
 276         }
 277
 278         adc->reg = devm_regulator_get(&spi->dev, "vref");
 279         if (IS_ERR(adc->reg))
 280                 return PTR_ERR(adc->reg);
 281
 282         ret = regulator_enable(adc->reg);
 283         if (ret)
 284                 return ret;
 285
 286         spi_set_drvdata(spi, indio_dev);
 287
 288         ret = iio_triggered_buffer_setup(indio_dev, NULL,
 289                                          adc0832_trigger_handler, NULL);
 290         if (ret)
 291                 goto err_reg_disable;
 292
 293         ret = iio_device_register(indio_dev);
 294         if (ret)
 295                 goto err_buffer_cleanup;
 296
 297         return 0;
 298 err_buffer_cleanup:
 299         iio_triggered_buffer_cleanup(indio_dev);
 300 err_reg_disable:
 301         regulator_disable(adc->reg);
 302
 303         return ret;
 304 }
 305
 306 static int adc0832_remove(struct spi_device *spi)
 307 {
 308         struct iio_dev *indio_dev = spi_get_drvdata(spi);
 309         struct adc0832 *adc = iio_priv(indio_dev);
 310
 311         iio_device_unregister(indio_dev);
 312         iio_triggered_buffer_cleanup(indio_dev);
 313         regulator_disable(adc->reg);
 314
 315         return 0;
 316 }
 317
 318 #ifdef CONFIG_OF
 319
 320 static const struct of_device_id adc0832_dt_ids[] = {
 321         { .compatible = "ti,adc0831", },
 322         { .compatible = "ti,adc0832", },
 323         { .compatible = "ti,adc0834", },
 324         { .compatible = "ti,adc0838", },
 325         {}
 326 };
 327 MODULE_DEVICE_TABLE(of, adc0832_dt_ids);
 328
 329 #endif
 330
 331 static const struct spi_device_id adc0832_id[] = {
 332         { "adc0831", adc0831 },
 333         { "adc0832", adc0832 },
 334         { "adc0834", adc0834 },
 335         { "adc0838", adc0838 },
 336         {}
 337 };
 338 MODULE_DEVICE_TABLE(spi, adc0832_id);
 339
 340 static struct spi_driver adc0832_driver = {
 341         .driver = {
 342                 .name = "adc0832",
 343                 .of_match_table = of_match_ptr(adc0832_dt_ids),
 344         },
 345         .probe = adc0832_probe,
 346         .remove = adc0832_remove,
 347         .id_table = adc0832_id,
 348 };
 349 module_spi_driver(adc0832_driver);
 350
 351 MODULE_AUTHOR("Akinobu Mita <akinobu.mita@gmail.com>");
 352 MODULE_DESCRIPTION("ADC0831/ADC0832/ADC0834/ADC0838 driver");
 353 MODULE_LICENSE("GPL v2");