drivers/iio/adc/ti-adc0832.c

   1 /*
   2  * ADC0831/ADC0832/ADC0834/ADC0838 8-bit ADC driver
   3  *
   4  * Copyright (c) 2016 Akinobu Mita <akinobu.mita@gmail.com>
   5  *
   6  * This file is subject to the terms and conditions of version 2 of
   7  * the GNU General Public License.  See the file COPYING in the main
   8  * directory of this archive for more details.
   9  *
  10  * Datasheet: http://www.ti.com/lit/ds/symlink/adc0832-n.pdf
  11  */
  12
  13 #include <linux/module.h>
  14 #include <linux/spi/spi.h>
  15 #include <linux/iio/iio.h>
  16 #include <linux/regulator/consumer.h>
  17 #include <linux/iio/buffer.h>
  18 #include <linux/iio/trigger.h>
  19 #include <linux/iio/triggered_buffer.h>
  20 #include <linux/iio/trigger_consumer.h>
  21
  22 enum {
  23         adc0831,
  24         adc0832,
  25         adc0834,
  26         adc0838,
  27 };
  28
  29 struct adc0832 {
  30         struct spi_device *spi;
  31         struct regulator *reg;
  32         struct mutex lock;
  33         u8 mux_bits;
  34         /*
  35          * Max size needed: 16x 1 byte ADC data + 8 bytes timestamp
  36          * May be shorter if not all channels are enabled subject
  37          * to the timestamp remaining 8 byte aligned.
  38          */
  39         u8 data[24] __aligned(8);
  40
  41         u8 tx_buf[2] ____cacheline_aligned;
  42         u8 rx_buf[2];
  43 };
  44
  45 #define ADC0832_VOLTAGE_CHANNEL(chan)                                   \
  46         {                                                               \
  47                 .type = IIO_VOLTAGE,                                    \
  48                 .indexed = 1,                                           \
  49                 .channel = chan,                                        \
  50                 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),           \
  51                 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),   \
  52                 .scan_index = chan,                                     \
  53                 .scan_type = {                                          \
  54                         .sign = 'u',                                    \
  55                         .realbits = 8,                                  \
  56                         .storagebits = 8,                               \
  57                 },                                                      \
  58         }
  59
  60 #define ADC0832_VOLTAGE_CHANNEL_DIFF(chan1, chan2, si)                  \
  61         {                                                               \
  62                 .type = IIO_VOLTAGE,                                    \
  63                 .indexed = 1,                                           \
  64                 .channel = (chan1),                                     \
  65                 .channel2 = (chan2),                                    \
  66                 .differential = 1,                                      \
  67                 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),           \
  68                 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),   \
  69                 .scan_index = si,                                       \
  70                 .scan_type = {                                          \
  71                         .sign = 'u',                                    \
  72                         .realbits = 8,                                  \
  73                         .storagebits = 8,                               \
  74                 },                                                      \
  75         }
  76
  77 static const struct iio_chan_spec adc0831_channels[] = {
  78         ADC0832_VOLTAGE_CHANNEL_DIFF(0, 1, 0),
  79         IIO_CHAN_SOFT_TIMESTAMP(1),
  80 };
  81
  82 static const struct iio_chan_spec adc0832_channels[] = {
  83         ADC0832_VOLTAGE_CHANNEL(0),
  84         ADC0832_VOLTAGE_CHANNEL(1),
  85         ADC0832_VOLTAGE_CHANNEL_DIFF(0, 1, 2),
  86         ADC0832_VOLTAGE_CHANNEL_DIFF(1, 0, 3),
  87         IIO_CHAN_SOFT_TIMESTAMP(4),
  88 };
  89
  90 static const struct iio_chan_spec adc0834_channels[] = {
  91         ADC0832_VOLTAGE_CHANNEL(0),
  92         ADC0832_VOLTAGE_CHANNEL(1),
  93         ADC0832_VOLTAGE_CHANNEL(2),
  94         ADC0832_VOLTAGE_CHANNEL(3),
  95         ADC0832_VOLTAGE_CHANNEL_DIFF(0, 1, 4),
  96         ADC0832_VOLTAGE_CHANNEL_DIFF(1, 0, 5),
  97         ADC0832_VOLTAGE_CHANNEL_DIFF(2, 3, 6),
  98         ADC0832_VOLTAGE_CHANNEL_DIFF(3, 2, 7),
  99         IIO_CHAN_SOFT_TIMESTAMP(8),
 100 };
 101
 102 static const struct iio_chan_spec adc0838_channels[] = {
 103         ADC0832_VOLTAGE_CHANNEL(0),
 104         ADC0832_VOLTAGE_CHANNEL(1),
 105         ADC0832_VOLTAGE_CHANNEL(2),
 106         ADC0832_VOLTAGE_CHANNEL(3),
 107         ADC0832_VOLTAGE_CHANNEL(4),
 108         ADC0832_VOLTAGE_CHANNEL(5),
 109         ADC0832_VOLTAGE_CHANNEL(6),
 110         ADC0832_VOLTAGE_CHANNEL(7),
 111         ADC0832_VOLTAGE_CHANNEL_DIFF(0, 1, 8),
 112         ADC0832_VOLTAGE_CHANNEL_DIFF(1, 0, 9),
 113         ADC0832_VOLTAGE_CHANNEL_DIFF(2, 3, 10),
 114         ADC0832_VOLTAGE_CHANNEL_DIFF(3, 2, 11),
 115         ADC0832_VOLTAGE_CHANNEL_DIFF(4, 5, 12),
 116         ADC0832_VOLTAGE_CHANNEL_DIFF(5, 4, 13),
 117         ADC0832_VOLTAGE_CHANNEL_DIFF(6, 7, 14),
 118         ADC0832_VOLTAGE_CHANNEL_DIFF(7, 6, 15),
 119         IIO_CHAN_SOFT_TIMESTAMP(16),
 120 };
 121
 122 static int adc0831_adc_conversion(struct adc0832 *adc)
 123 {
 124         struct spi_device *spi = adc->spi;
 125         int ret;
 126
 127         ret = spi_read(spi, &adc->rx_buf, 2);
 128         if (ret)
 129                 return ret;
 130
 131         /*
 132          * Skip TRI-STATE and a leading zero
 133          */
 134         return (adc->rx_buf[0] << 2 & 0xff) | (adc->rx_buf[1] >> 6);
 135 }
 136
 137 static int adc0832_adc_conversion(struct adc0832 *adc, int channel,
 138                                 bool differential)
 139 {
 140         struct spi_device *spi = adc->spi;
 141         struct spi_transfer xfer = {
 142                 .tx_buf = adc->tx_buf,
 143                 .rx_buf = adc->rx_buf,
 144                 .len = 2,
 145         };
 146         int ret;
 147
 148         if (!adc->mux_bits)
 149                 return adc0831_adc_conversion(adc);
 150
 151         /* start bit */
 152         adc->tx_buf[0] = 1 << (adc->mux_bits + 1);
 153         /* single-ended or differential */
 154         adc->tx_buf[0] |= differential ? 0 : (1 << adc->mux_bits);
 155         /* odd / sign */
 156         adc->tx_buf[0] |= (channel % 2) << (adc->mux_bits - 1);
 157         /* select */
 158         if (adc->mux_bits > 1)
 159                 adc->tx_buf[0] |= channel / 2;
 160
 161         /* align Data output BIT7 (MSB) to 8-bit boundary */
 162         adc->tx_buf[0] <<= 1;
 163
 164         ret = spi_sync_transfer(spi, &xfer, 1);
 165         if (ret)
 166                 return ret;
 167
 168         return adc->rx_buf[1];
 169 }
 170
 171 static int adc0832_read_raw(struct iio_dev *iio,
 172                         struct iio_chan_spec const *channel, int *value,
 173                         int *shift, long mask)
 174 {
 175         struct adc0832 *adc = iio_priv(iio);
 176
 177         switch (mask) {
 178         case IIO_CHAN_INFO_RAW:
 179                 mutex_lock(&adc->lock);
 180                 *value = adc0832_adc_conversion(adc, channel->channel,
 181                                                 channel->differential);
 182                 mutex_unlock(&adc->lock);
 183                 if (*value < 0)
 184                         return *value;
 185
 186                 return IIO_VAL_INT;
 187         case IIO_CHAN_INFO_SCALE:
 188                 *value = regulator_get_voltage(adc->reg);
 189                 if (*value < 0)
 190                         return *value;
 191
 192                 /* convert regulator output voltage to mV */
 193                 *value /= 1000;
 194                 *shift = 8;
 195
 196                 return IIO_VAL_FRACTIONAL_LOG2;
 197         }
 198
 199         return -EINVAL;
 200 }
 201
 202 static const struct iio_info adc0832_info = {
 203         .read_raw = adc0832_read_raw,
 204 };
 205
 206 static irqreturn_t adc0832_trigger_handler(int irq, void *p)
 207 {
 208         struct iio_poll_func *pf = p;
 209         struct iio_dev *indio_dev = pf->indio_dev;
 210         struct adc0832 *adc = iio_priv(indio_dev);
 211         int scan_index;
 212         int i = 0;
 213
 214         mutex_lock(&adc->lock);
 215
 216         for_each_set_bit(scan_index, indio_dev->active_scan_mask,
 217                          indio_dev->masklength) {
 218                 const struct iio_chan_spec *scan_chan =
 219                                 &indio_dev->channels[scan_index];
 220                 int ret = adc0832_adc_conversion(adc, scan_chan->channel,
 221                                                  scan_chan->differential);
 222                 if (ret < 0) {
 223                         dev_warn(&adc->spi->dev,
 224                                  "failed to get conversion data\n");
 225                         goto out;
 226                 }
 227
 228                 adc->data[i] = ret;
 229                 i++;
 230         }
 231         iio_push_to_buffers_with_timestamp(indio_dev, adc->data,
 232                                            iio_get_time_ns(indio_dev));
 233 out:
 234         mutex_unlock(&adc->lock);
 235
 236         iio_trigger_notify_done(indio_dev->trig);
 237
 238         return IRQ_HANDLED;
 239 }
 240
 241 static int adc0832_probe(struct spi_device *spi)
 242 {
 243         struct iio_dev *indio_dev;
 244         struct adc0832 *adc;
 245         int ret;
 246
 247         indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*adc));
 248         if (!indio_dev)
 249                 return -ENOMEM;
 250
 251         adc = iio_priv(indio_dev);
 252         adc->spi = spi;
 253         mutex_init(&adc->lock);
 254
 255         indio_dev->name = spi_get_device_id(spi)->name;
 256         indio_dev->dev.parent = &spi->dev;
 257         indio_dev->dev.of_node = spi->dev.of_node;
 258         indio_dev->info = &adc0832_info;
 259         indio_dev->modes = INDIO_DIRECT_MODE;
 260
 261         switch (spi_get_device_id(spi)->driver_data) {
 262         case adc0831:
 263                 adc->mux_bits = 0;
 264                 indio_dev->channels = adc0831_channels;
 265                 indio_dev->num_channels = ARRAY_SIZE(adc0831_channels);
 266                 break;
 267         case adc0832:
 268                 adc->mux_bits = 1;
 269                 indio_dev->channels = adc0832_channels;
 270                 indio_dev->num_channels = ARRAY_SIZE(adc0832_channels);
 271                 break;
 272         case adc0834:
 273                 adc->mux_bits = 2;
 274                 indio_dev->channels = adc0834_channels;
 275                 indio_dev->num_channels = ARRAY_SIZE(adc0834_channels);
 276                 break;
 277         case adc0838:
 278                 adc->mux_bits = 3;
 279                 indio_dev->channels = adc0838_channels;
 280                 indio_dev->num_channels = ARRAY_SIZE(adc0838_channels);
 281                 break;
 282         default:
 283                 return -EINVAL;
 284         }
 285
 286         adc->reg = devm_regulator_get(&spi->dev, "vref");
 287         if (IS_ERR(adc->reg))
 288                 return PTR_ERR(adc->reg);
 289
 290         ret = regulator_enable(adc->reg);
 291         if (ret)
 292                 return ret;
 293
 294         spi_set_drvdata(spi, indio_dev);
 295
 296         ret = iio_triggered_buffer_setup(indio_dev, NULL,
 297                                          adc0832_trigger_handler, NULL);
 298         if (ret)
 299                 goto err_reg_disable;
 300
 301         ret = iio_device_register(indio_dev);
 302         if (ret)
 303                 goto err_buffer_cleanup;
 304
 305         return 0;
 306 err_buffer_cleanup:
 307         iio_triggered_buffer_cleanup(indio_dev);
 308 err_reg_disable:
 309         regulator_disable(adc->reg);
 310
 311         return ret;
 312 }
 313
 314 static int adc0832_remove(struct spi_device *spi)
 315 {
 316         struct iio_dev *indio_dev = spi_get_drvdata(spi);
 317         struct adc0832 *adc = iio_priv(indio_dev);
 318
 319         iio_device_unregister(indio_dev);
 320         iio_triggered_buffer_cleanup(indio_dev);
 321         regulator_disable(adc->reg);
 322
 323         return 0;
 324 }
 325
 326 #ifdef CONFIG_OF
 327
 328 static const struct of_device_id adc0832_dt_ids[] = {
 329         { .compatible = "ti,adc0831", },
 330         { .compatible = "ti,adc0832", },
 331         { .compatible = "ti,adc0834", },
 332         { .compatible = "ti,adc0838", },
 333         {}
 334 };
 335 MODULE_DEVICE_TABLE(of, adc0832_dt_ids);
 336
 337 #endif
 338
 339 static const struct spi_device_id adc0832_id[] = {
 340         { "adc0831", adc0831 },
 341         { "adc0832", adc0832 },
 342         { "adc0834", adc0834 },
 343         { "adc0838", adc0838 },
 344         {}
 345 };
 346 MODULE_DEVICE_TABLE(spi, adc0832_id);
 347
 348 static struct spi_driver adc0832_driver = {
 349         .driver = {
 350                 .name = "adc0832",
 351                 .of_match_table = of_match_ptr(adc0832_dt_ids),
 352         },
 353         .probe = adc0832_probe,
 354         .remove = adc0832_remove,
 355         .id_table = adc0832_id,
 356 };
 357 module_spi_driver(adc0832_driver);
 358
 359 MODULE_AUTHOR("Akinobu Mita <akinobu.mita@gmail.com>");
 360 MODULE_DESCRIPTION("ADC0831/ADC0832/ADC0834/ADC0838 driver");
 361 MODULE_LICENSE("GPL v2");