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: https://www.ti.com/lit/ds/symlink/adc0832-n.pdf
   8  */
   9
  10 #include <linux/module.h>
  11 #include <linux/mod_devicetable.h>
  12 #include <linux/spi/spi.h>
  13 #include <linux/iio/iio.h>
  14 #include <linux/regulator/consumer.h>
  15 #include <linux/iio/buffer.h>
  16 #include <linux/iio/trigger.h>
  17 #include <linux/iio/triggered_buffer.h>
  18 #include <linux/iio/trigger_consumer.h>
  19
  20 enum {
  21         adc0831,
  22         adc0832,
  23         adc0834,
  24         adc0838,
  25 };
  26
  27 struct adc0832 {
  28         struct spi_device *spi;
  29         struct regulator *reg;
  30         struct mutex lock;
  31         u8 mux_bits;
  32         /*
  33          * Max size needed: 16x 1 byte ADC data + 8 bytes timestamp
  34          * May be shorter if not all channels are enabled subject
  35          * to the timestamp remaining 8 byte aligned.
  36          */
  37         u8 data[24] __aligned(8);
  38
  39         u8 tx_buf[2] __aligned(IIO_DMA_MINALIGN);
  40         u8 rx_buf[2];
  41 };
  42
  43 #define ADC0832_VOLTAGE_CHANNEL(chan)                                   \
  44         {                                                               \
  45                 .type = IIO_VOLTAGE,                                    \
  46                 .indexed = 1,                                           \
  47                 .channel = chan,                                        \
  48                 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),           \
  49                 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),   \
  50                 .scan_index = chan,                                     \
  51                 .scan_type = {                                          \
  52                         .sign = 'u',                                    \
  53                         .realbits = 8,                                  \
  54                         .storagebits = 8,                               \
  55                 },                                                      \
  56         }
  57
  58 #define ADC0832_VOLTAGE_CHANNEL_DIFF(chan1, chan2, si)                  \
  59         {                                                               \
  60                 .type = IIO_VOLTAGE,                                    \
  61                 .indexed = 1,                                           \
  62                 .channel = (chan1),                                     \
  63                 .channel2 = (chan2),                                    \
  64                 .differential = 1,                                      \
  65                 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),           \
  66                 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),   \
  67                 .scan_index = si,                                       \
  68                 .scan_type = {                                          \
  69                         .sign = 'u',                                    \
  70                         .realbits = 8,                                  \
  71                         .storagebits = 8,                               \
  72                 },                                                      \
  73         }
  74
  75 static const struct iio_chan_spec adc0831_channels[] = {
  76         ADC0832_VOLTAGE_CHANNEL_DIFF(0, 1, 0),
  77         IIO_CHAN_SOFT_TIMESTAMP(1),
  78 };
  79
  80 static const struct iio_chan_spec adc0832_channels[] = {
  81         ADC0832_VOLTAGE_CHANNEL(0),
  82         ADC0832_VOLTAGE_CHANNEL(1),
  83         ADC0832_VOLTAGE_CHANNEL_DIFF(0, 1, 2),
  84         ADC0832_VOLTAGE_CHANNEL_DIFF(1, 0, 3),
  85         IIO_CHAN_SOFT_TIMESTAMP(4),
  86 };
  87
  88 static const struct iio_chan_spec adc0834_channels[] = {
  89         ADC0832_VOLTAGE_CHANNEL(0),
  90         ADC0832_VOLTAGE_CHANNEL(1),
  91         ADC0832_VOLTAGE_CHANNEL(2),
  92         ADC0832_VOLTAGE_CHANNEL(3),
  93         ADC0832_VOLTAGE_CHANNEL_DIFF(0, 1, 4),
  94         ADC0832_VOLTAGE_CHANNEL_DIFF(1, 0, 5),
  95         ADC0832_VOLTAGE_CHANNEL_DIFF(2, 3, 6),
  96         ADC0832_VOLTAGE_CHANNEL_DIFF(3, 2, 7),
  97         IIO_CHAN_SOFT_TIMESTAMP(8),
  98 };
  99
 100 static const struct iio_chan_spec adc0838_channels[] = {
 101         ADC0832_VOLTAGE_CHANNEL(0),
 102         ADC0832_VOLTAGE_CHANNEL(1),
 103         ADC0832_VOLTAGE_CHANNEL(2),
 104         ADC0832_VOLTAGE_CHANNEL(3),
 105         ADC0832_VOLTAGE_CHANNEL(4),
 106         ADC0832_VOLTAGE_CHANNEL(5),
 107         ADC0832_VOLTAGE_CHANNEL(6),
 108         ADC0832_VOLTAGE_CHANNEL(7),
 109         ADC0832_VOLTAGE_CHANNEL_DIFF(0, 1, 8),
 110         ADC0832_VOLTAGE_CHANNEL_DIFF(1, 0, 9),
 111         ADC0832_VOLTAGE_CHANNEL_DIFF(2, 3, 10),
 112         ADC0832_VOLTAGE_CHANNEL_DIFF(3, 2, 11),
 113         ADC0832_VOLTAGE_CHANNEL_DIFF(4, 5, 12),
 114         ADC0832_VOLTAGE_CHANNEL_DIFF(5, 4, 13),
 115         ADC0832_VOLTAGE_CHANNEL_DIFF(6, 7, 14),
 116         ADC0832_VOLTAGE_CHANNEL_DIFF(7, 6, 15),
 117         IIO_CHAN_SOFT_TIMESTAMP(16),
 118 };
 119
 120 static int adc0831_adc_conversion(struct adc0832 *adc)
 121 {
 122         struct spi_device *spi = adc->spi;
 123         int ret;
 124
 125         ret = spi_read(spi, &adc->rx_buf, 2);
 126         if (ret)
 127                 return ret;
 128
 129         /*
 130          * Skip TRI-STATE and a leading zero
 131          */
 132         return (adc->rx_buf[0] << 2 & 0xff) | (adc->rx_buf[1] >> 6);
 133 }
 134
 135 static int adc0832_adc_conversion(struct adc0832 *adc, int channel,
 136                                 bool differential)
 137 {
 138         struct spi_device *spi = adc->spi;
 139         struct spi_transfer xfer = {
 140                 .tx_buf = adc->tx_buf,
 141                 .rx_buf = adc->rx_buf,
 142                 .len = 2,
 143         };
 144         int ret;
 145
 146         if (!adc->mux_bits)
 147                 return adc0831_adc_conversion(adc);
 148
 149         /* start bit */
 150         adc->tx_buf[0] = 1 << (adc->mux_bits + 1);
 151         /* single-ended or differential */
 152         adc->tx_buf[0] |= differential ? 0 : (1 << adc->mux_bits);
 153         /* odd / sign */
 154         adc->tx_buf[0] |= (channel % 2) << (adc->mux_bits - 1);
 155         /* select */
 156         if (adc->mux_bits > 1)
 157                 adc->tx_buf[0] |= channel / 2;
 158
 159         /* align Data output BIT7 (MSB) to 8-bit boundary */
 160         adc->tx_buf[0] <<= 1;
 161
 162         ret = spi_sync_transfer(spi, &xfer, 1);
 163         if (ret)
 164                 return ret;
 165
 166         return adc->rx_buf[1];
 167 }
 168
 169 static int adc0832_read_raw(struct iio_dev *iio,
 170                         struct iio_chan_spec const *channel, int *value,
 171                         int *shift, long mask)
 172 {
 173         struct adc0832 *adc = iio_priv(iio);
 174
 175         switch (mask) {
 176         case IIO_CHAN_INFO_RAW:
 177                 mutex_lock(&adc->lock);
 178                 *value = adc0832_adc_conversion(adc, channel->channel,
 179                                                 channel->differential);
 180                 mutex_unlock(&adc->lock);
 181                 if (*value < 0)
 182                         return *value;
 183
 184                 return IIO_VAL_INT;
 185         case IIO_CHAN_INFO_SCALE:
 186                 *value = regulator_get_voltage(adc->reg);
 187                 if (*value < 0)
 188                         return *value;
 189
 190                 /* convert regulator output voltage to mV */
 191                 *value /= 1000;
 192                 *shift = 8;
 193
 194                 return IIO_VAL_FRACTIONAL_LOG2;
 195         }
 196
 197         return -EINVAL;
 198 }
 199
 200 static const struct iio_info adc0832_info = {
 201         .read_raw = adc0832_read_raw,
 202 };
 203
 204 static irqreturn_t adc0832_trigger_handler(int irq, void *p)
 205 {
 206         struct iio_poll_func *pf = p;
 207         struct iio_dev *indio_dev = pf->indio_dev;
 208         struct adc0832 *adc = iio_priv(indio_dev);
 209         int scan_index;
 210         int i = 0;
 211
 212         mutex_lock(&adc->lock);
 213
 214         iio_for_each_active_channel(indio_dev, scan_index) {
 215                 const struct iio_chan_spec *scan_chan =
 216                                 &indio_dev->channels[scan_index];
 217                 int ret = adc0832_adc_conversion(adc, scan_chan->channel,
 218                                                  scan_chan->differential);
 219                 if (ret < 0) {
 220                         dev_warn(&adc->spi->dev,
 221                                  "failed to get conversion data\n");
 222                         goto out;
 223                 }
 224
 225                 adc->data[i] = ret;
 226                 i++;
 227         }
 228         iio_push_to_buffers_with_timestamp(indio_dev, adc->data,
 229                                            iio_get_time_ns(indio_dev));
 230 out:
 231         mutex_unlock(&adc->lock);
 232
 233         iio_trigger_notify_done(indio_dev->trig);
 234
 235         return IRQ_HANDLED;
 236 }
 237
 238 static void adc0832_reg_disable(void *reg)
 239 {
 240         regulator_disable(reg);
 241 }
 242
 243 static int adc0832_probe(struct spi_device *spi)
 244 {
 245         struct iio_dev *indio_dev;
 246         struct adc0832 *adc;
 247         int ret;
 248
 249         indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*adc));
 250         if (!indio_dev)
 251                 return -ENOMEM;
 252
 253         adc = iio_priv(indio_dev);
 254         adc->spi = spi;
 255         mutex_init(&adc->lock);
 256
 257         indio_dev->name = spi_get_device_id(spi)->name;
 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         ret = devm_add_action_or_reset(&spi->dev, adc0832_reg_disable,
 295                                        adc->reg);
 296         if (ret)
 297                 return ret;
 298
 299         ret = devm_iio_triggered_buffer_setup(&spi->dev, indio_dev, NULL,
 300                                               adc0832_trigger_handler, NULL);
 301         if (ret)
 302                 return ret;
 303
 304         return devm_iio_device_register(&spi->dev, indio_dev);
 305 }
 306
 307 static const struct of_device_id adc0832_dt_ids[] = {
 308         { .compatible = "ti,adc0831", },
 309         { .compatible = "ti,adc0832", },
 310         { .compatible = "ti,adc0834", },
 311         { .compatible = "ti,adc0838", },
 312         { }
 313 };
 314 MODULE_DEVICE_TABLE(of, adc0832_dt_ids);
 315
 316 static const struct spi_device_id adc0832_id[] = {
 317         { "adc0831", adc0831 },
 318         { "adc0832", adc0832 },
 319         { "adc0834", adc0834 },
 320         { "adc0838", adc0838 },
 321         { }
 322 };
 323 MODULE_DEVICE_TABLE(spi, adc0832_id);
 324
 325 static struct spi_driver adc0832_driver = {
 326         .driver = {
 327                 .name = "adc0832",
 328                 .of_match_table = adc0832_dt_ids,
 329         },
 330         .probe = adc0832_probe,
 331         .id_table = adc0832_id,
 332 };
 333 module_spi_driver(adc0832_driver);
 334
 335 MODULE_AUTHOR("Akinobu Mita <akinobu.mita@gmail.com>");
 336 MODULE_DESCRIPTION("ADC0831/ADC0832/ADC0834/ADC0838 driver");
 337 MODULE_LICENSE("GPL v2");