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
  18 enum {
  19         adc0831,
  20         adc0832,
  21         adc0834,
  22         adc0838,
  23 };
  24
  25 struct adc0832 {
  26         struct spi_device *spi;
  27         struct regulator *reg;
  28         struct mutex lock;
  29         u8 mux_bits;
  30
  31         u8 tx_buf[2] ____cacheline_aligned;
  32         u8 rx_buf[2];
  33 };
  34
  35 #define ADC0832_VOLTAGE_CHANNEL(chan)                                   \
  36         {                                                               \
  37                 .type = IIO_VOLTAGE,                                    \
  38                 .indexed = 1,                                           \
  39                 .channel = chan,                                        \
  40                 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),           \
  41                 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE)    \
  42         }
  43
  44 #define ADC0832_VOLTAGE_CHANNEL_DIFF(chan1, chan2)                      \
  45         {                                                               \
  46                 .type = IIO_VOLTAGE,                                    \
  47                 .indexed = 1,                                           \
  48                 .channel = (chan1),                                     \
  49                 .channel2 = (chan2),                                    \
  50                 .differential = 1,                                      \
  51                 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),           \
  52                 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE)    \
  53         }
  54
  55 static const struct iio_chan_spec adc0831_channels[] = {
  56         ADC0832_VOLTAGE_CHANNEL_DIFF(0, 1),
  57 };
  58
  59 static const struct iio_chan_spec adc0832_channels[] = {
  60         ADC0832_VOLTAGE_CHANNEL(0),
  61         ADC0832_VOLTAGE_CHANNEL(1),
  62         ADC0832_VOLTAGE_CHANNEL_DIFF(0, 1),
  63         ADC0832_VOLTAGE_CHANNEL_DIFF(1, 0),
  64 };
  65
  66 static const struct iio_chan_spec adc0834_channels[] = {
  67         ADC0832_VOLTAGE_CHANNEL(0),
  68         ADC0832_VOLTAGE_CHANNEL(1),
  69         ADC0832_VOLTAGE_CHANNEL(2),
  70         ADC0832_VOLTAGE_CHANNEL(3),
  71         ADC0832_VOLTAGE_CHANNEL_DIFF(0, 1),
  72         ADC0832_VOLTAGE_CHANNEL_DIFF(1, 0),
  73         ADC0832_VOLTAGE_CHANNEL_DIFF(2, 3),
  74         ADC0832_VOLTAGE_CHANNEL_DIFF(3, 2),
  75 };
  76
  77 static const struct iio_chan_spec adc0838_channels[] = {
  78         ADC0832_VOLTAGE_CHANNEL(0),
  79         ADC0832_VOLTAGE_CHANNEL(1),
  80         ADC0832_VOLTAGE_CHANNEL(2),
  81         ADC0832_VOLTAGE_CHANNEL(3),
  82         ADC0832_VOLTAGE_CHANNEL(4),
  83         ADC0832_VOLTAGE_CHANNEL(5),
  84         ADC0832_VOLTAGE_CHANNEL(6),
  85         ADC0832_VOLTAGE_CHANNEL(7),
  86         ADC0832_VOLTAGE_CHANNEL_DIFF(0, 1),
  87         ADC0832_VOLTAGE_CHANNEL_DIFF(1, 0),
  88         ADC0832_VOLTAGE_CHANNEL_DIFF(2, 3),
  89         ADC0832_VOLTAGE_CHANNEL_DIFF(3, 2),
  90         ADC0832_VOLTAGE_CHANNEL_DIFF(4, 5),
  91         ADC0832_VOLTAGE_CHANNEL_DIFF(5, 4),
  92         ADC0832_VOLTAGE_CHANNEL_DIFF(6, 7),
  93         ADC0832_VOLTAGE_CHANNEL_DIFF(7, 6),
  94 };
  95
  96 static int adc0831_adc_conversion(struct adc0832 *adc)
  97 {
  98         struct spi_device *spi = adc->spi;
  99         int ret;
 100
 101         ret = spi_read(spi, &adc->rx_buf, 2);
 102         if (ret)
 103                 return ret;
 104
 105         /*
 106          * Skip TRI-STATE and a leading zero
 107          */
 108         return (adc->rx_buf[0] << 2 & 0xff) | (adc->rx_buf[1] >> 6);
 109 }
 110
 111 static int adc0832_adc_conversion(struct adc0832 *adc, int channel,
 112                                 bool differential)
 113 {
 114         struct spi_device *spi = adc->spi;
 115         struct spi_transfer xfer = {
 116                 .tx_buf = adc->tx_buf,
 117                 .rx_buf = adc->rx_buf,
 118                 .len = 2,
 119         };
 120         int ret;
 121
 122         if (!adc->mux_bits)
 123                 return adc0831_adc_conversion(adc);
 124
 125         /* start bit */
 126         adc->tx_buf[0] = 1 << (adc->mux_bits + 1);
 127         /* single-ended or differential */
 128         adc->tx_buf[0] |= differential ? 0 : (1 << adc->mux_bits);
 129         /* odd / sign */
 130         adc->tx_buf[0] |= (channel % 2) << (adc->mux_bits - 1);
 131         /* select */
 132         if (adc->mux_bits > 1)
 133                 adc->tx_buf[0] |= channel / 2;
 134
 135         /* align Data output BIT7 (MSB) to 8-bit boundary */
 136         adc->tx_buf[0] <<= 1;
 137
 138         ret = spi_sync_transfer(spi, &xfer, 1);
 139         if (ret)
 140                 return ret;
 141
 142         return adc->rx_buf[1];
 143 }
 144
 145 static int adc0832_read_raw(struct iio_dev *iio,
 146                         struct iio_chan_spec const *channel, int *value,
 147                         int *shift, long mask)
 148 {
 149         struct adc0832 *adc = iio_priv(iio);
 150
 151         switch (mask) {
 152         case IIO_CHAN_INFO_RAW:
 153                 mutex_lock(&adc->lock);
 154                 *value = adc0832_adc_conversion(adc, channel->channel,
 155                                                 channel->differential);
 156                 mutex_unlock(&adc->lock);
 157                 if (*value < 0)
 158                         return *value;
 159
 160                 return IIO_VAL_INT;
 161         case IIO_CHAN_INFO_SCALE:
 162                 *value = regulator_get_voltage(adc->reg);
 163                 if (*value < 0)
 164                         return *value;
 165
 166                 /* convert regulator output voltage to mV */
 167                 *value /= 1000;
 168                 *shift = 8;
 169
 170                 return IIO_VAL_FRACTIONAL_LOG2;
 171         }
 172
 173         return -EINVAL;
 174 }
 175
 176 static const struct iio_info adc0832_info = {
 177         .read_raw = adc0832_read_raw,
 178         .driver_module = THIS_MODULE,
 179 };
 180
 181 static int adc0832_probe(struct spi_device *spi)
 182 {
 183         struct iio_dev *indio_dev;
 184         struct adc0832 *adc;
 185         int ret;
 186
 187         indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*adc));
 188         if (!indio_dev)
 189                 return -ENOMEM;
 190
 191         adc = iio_priv(indio_dev);
 192         adc->spi = spi;
 193         mutex_init(&adc->lock);
 194
 195         indio_dev->name = spi_get_device_id(spi)->name;
 196         indio_dev->dev.parent = &spi->dev;
 197         indio_dev->dev.of_node = spi->dev.of_node;
 198         indio_dev->info = &adc0832_info;
 199         indio_dev->modes = INDIO_DIRECT_MODE;
 200
 201         switch (spi_get_device_id(spi)->driver_data) {
 202         case adc0831:
 203                 adc->mux_bits = 0;
 204                 indio_dev->channels = adc0831_channels;
 205                 indio_dev->num_channels = ARRAY_SIZE(adc0831_channels);
 206                 break;
 207         case adc0832:
 208                 adc->mux_bits = 1;
 209                 indio_dev->channels = adc0832_channels;
 210                 indio_dev->num_channels = ARRAY_SIZE(adc0832_channels);
 211                 break;
 212         case adc0834:
 213                 adc->mux_bits = 2;
 214                 indio_dev->channels = adc0834_channels;
 215                 indio_dev->num_channels = ARRAY_SIZE(adc0834_channels);
 216                 break;
 217         case adc0838:
 218                 adc->mux_bits = 3;
 219                 indio_dev->channels = adc0838_channels;
 220                 indio_dev->num_channels = ARRAY_SIZE(adc0838_channels);
 221                 break;
 222         default:
 223                 return -EINVAL;
 224         }
 225
 226         adc->reg = devm_regulator_get(&spi->dev, "vref");
 227         if (IS_ERR(adc->reg))
 228                 return PTR_ERR(adc->reg);
 229
 230         ret = regulator_enable(adc->reg);
 231         if (ret)
 232                 return ret;
 233
 234         spi_set_drvdata(spi, indio_dev);
 235
 236         ret = iio_device_register(indio_dev);
 237         if (ret)
 238                 regulator_disable(adc->reg);
 239
 240         return ret;
 241 }
 242
 243 static int adc0832_remove(struct spi_device *spi)
 244 {
 245         struct iio_dev *indio_dev = spi_get_drvdata(spi);
 246         struct adc0832 *adc = iio_priv(indio_dev);
 247
 248         iio_device_unregister(indio_dev);
 249         regulator_disable(adc->reg);
 250
 251         return 0;
 252 }
 253
 254 #ifdef CONFIG_OF
 255
 256 static const struct of_device_id adc0832_dt_ids[] = {
 257         { .compatible = "ti,adc0831", },
 258         { .compatible = "ti,adc0832", },
 259         { .compatible = "ti,adc0834", },
 260         { .compatible = "ti,adc0838", },
 261         {}
 262 };
 263 MODULE_DEVICE_TABLE(of, adc0832_dt_ids);
 264
 265 #endif
 266
 267 static const struct spi_device_id adc0832_id[] = {
 268         { "adc0831", adc0831 },
 269         { "adc0832", adc0832 },
 270         { "adc0834", adc0834 },
 271         { "adc0838", adc0838 },
 272         {}
 273 };
 274 MODULE_DEVICE_TABLE(spi, adc0832_id);
 275
 276 static struct spi_driver adc0832_driver = {
 277         .driver = {
 278                 .name = "adc0832",
 279                 .of_match_table = of_match_ptr(adc0832_dt_ids),
 280         },
 281         .probe = adc0832_probe,
 282         .remove = adc0832_remove,
 283         .id_table = adc0832_id,
 284 };
 285 module_spi_driver(adc0832_driver);
 286
 287 MODULE_AUTHOR("Akinobu Mita <akinobu.mita@gmail.com>");
 288 MODULE_DESCRIPTION("ADC0831/ADC0832/ADC0834/ADC0838 driver");
 289 MODULE_LICENSE("GPL v2");