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