drivers/iio/adc/max1118.c

   1 /*
   2  * MAX1117/MAX1118/MAX1119 8-bit, dual-channel ADCs driver
   3  *
   4  * Copyright (c) 2017 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: https://datasheets.maximintegrated.com/en/ds/MAX1117-MAX1119.pdf
  11  *
  12  * SPI interface connections
  13  *
  14  * SPI                MAXIM
  15  * Master  Direction  MAX1117/8/9
  16  * ------  ---------  -----------
  17  * nCS        -->     CNVST
  18  * SCK        -->     SCLK
  19  * MISO       <--     DOUT
  20  * ------  ---------  -----------
  21  */
  22
  23 #include <linux/module.h>
  24 #include <linux/spi/spi.h>
  25 #include <linux/iio/iio.h>
  26 #include <linux/iio/buffer.h>
  27 #include <linux/iio/triggered_buffer.h>
  28 #include <linux/iio/trigger_consumer.h>
  29 #include <linux/regulator/consumer.h>
  30
  31 enum max1118_id {
  32         max1117,
  33         max1118,
  34         max1119,
  35 };
  36
  37 struct max1118 {
  38         struct spi_device *spi;
  39         struct mutex lock;
  40         struct regulator *reg;
  41
  42         u8 data ____cacheline_aligned;
  43 };
  44
  45 #define MAX1118_CHANNEL(ch)                                             \
  46         {                                                               \
  47                 .type = IIO_VOLTAGE,                                    \
  48                 .indexed = 1,                                           \
  49                 .channel = (ch),                                        \
  50                 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),           \
  51                 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),   \
  52                 .scan_index = ch,                                       \
  53                 .scan_type = {                                          \
  54                         .sign = 'u',                                    \
  55                         .realbits = 8,                                  \
  56                         .storagebits = 8,                               \
  57                 },                                                      \
  58         }
  59
  60 static const struct iio_chan_spec max1118_channels[] = {
  61         MAX1118_CHANNEL(0),
  62         MAX1118_CHANNEL(1),
  63         IIO_CHAN_SOFT_TIMESTAMP(2),
  64 };
  65
  66 static int max1118_read(struct spi_device *spi, int channel)
  67 {
  68         struct iio_dev *indio_dev = spi_get_drvdata(spi);
  69         struct max1118 *adc = iio_priv(indio_dev);
  70         struct spi_transfer xfers[] = {
  71                 /*
  72                  * To select CH1 for conversion, CNVST pin must be brought high
  73                  * and low for a second time.
  74                  */
  75                 {
  76                         .len = 0,
  77                         .delay_usecs = 1,       /* > CNVST Low Time 100 ns */
  78                         .cs_change = 1,
  79                 },
  80                 /*
  81                  * The acquisition interval begins with the falling edge of
  82                  * CNVST.  The total acquisition and conversion process takes
  83                  * <7.5us.
  84                  */
  85                 {
  86                         .len = 0,
  87                         .delay_usecs = 8,
  88                 },
  89                 {
  90                         .rx_buf = &adc->data,
  91                         .len = 1,
  92                 },
  93         };
  94         int ret;
  95
  96         if (channel == 0)
  97                 ret = spi_sync_transfer(spi, xfers + 1, 2);
  98         else
  99                 ret = spi_sync_transfer(spi, xfers, 3);
 100
 101         if (ret)
 102                 return ret;
 103
 104         return adc->data;
 105 }
 106
 107 static int max1118_get_vref_mV(struct spi_device *spi)
 108 {
 109         struct iio_dev *indio_dev = spi_get_drvdata(spi);
 110         struct max1118 *adc = iio_priv(indio_dev);
 111         const struct spi_device_id *id = spi_get_device_id(spi);
 112         int vref_uV;
 113
 114         switch (id->driver_data) {
 115         case max1117:
 116                 return 2048;
 117         case max1119:
 118                 return 4096;
 119         case max1118:
 120                 vref_uV = regulator_get_voltage(adc->reg);
 121                 if (vref_uV < 0)
 122                         return vref_uV;
 123                 return vref_uV / 1000;
 124         }
 125
 126         return -ENODEV;
 127 }
 128
 129 static int max1118_read_raw(struct iio_dev *indio_dev,
 130                         struct iio_chan_spec const *chan,
 131                         int *val, int *val2, long mask)
 132 {
 133         struct max1118 *adc = iio_priv(indio_dev);
 134
 135         switch (mask) {
 136         case IIO_CHAN_INFO_RAW:
 137                 mutex_lock(&adc->lock);
 138                 *val = max1118_read(adc->spi, chan->channel);
 139                 mutex_unlock(&adc->lock);
 140                 if (*val < 0)
 141                         return *val;
 142
 143                 return IIO_VAL_INT;
 144         case IIO_CHAN_INFO_SCALE:
 145                 *val = max1118_get_vref_mV(adc->spi);
 146                 if (*val < 0)
 147                         return *val;
 148                 *val2 = 8;
 149
 150                 return IIO_VAL_FRACTIONAL_LOG2;
 151         }
 152
 153         return -EINVAL;
 154 }
 155
 156 static const struct iio_info max1118_info = {
 157         .read_raw = max1118_read_raw,
 158 };
 159
 160 static irqreturn_t max1118_trigger_handler(int irq, void *p)
 161 {
 162         struct iio_poll_func *pf = p;
 163         struct iio_dev *indio_dev = pf->indio_dev;
 164         struct max1118 *adc = iio_priv(indio_dev);
 165         u8 data[16] = { }; /* 2x 8-bit ADC data + padding + 8 bytes timestamp */
 166         int scan_index;
 167         int i = 0;
 168
 169         mutex_lock(&adc->lock);
 170
 171         for_each_set_bit(scan_index, indio_dev->active_scan_mask,
 172                         indio_dev->masklength) {
 173                 const struct iio_chan_spec *scan_chan =
 174                                 &indio_dev->channels[scan_index];
 175                 int ret = max1118_read(adc->spi, scan_chan->channel);
 176
 177                 if (ret < 0) {
 178                         dev_warn(&adc->spi->dev,
 179                                 "failed to get conversion data\n");
 180                         goto out;
 181                 }
 182
 183                 data[i] = ret;
 184                 i++;
 185         }
 186         iio_push_to_buffers_with_timestamp(indio_dev, data,
 187                                            iio_get_time_ns(indio_dev));
 188 out:
 189         mutex_unlock(&adc->lock);
 190
 191         iio_trigger_notify_done(indio_dev->trig);
 192
 193         return IRQ_HANDLED;
 194 }
 195
 196 static int max1118_probe(struct spi_device *spi)
 197 {
 198         struct iio_dev *indio_dev;
 199         struct max1118 *adc;
 200         const struct spi_device_id *id = spi_get_device_id(spi);
 201         int ret;
 202
 203         indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*adc));
 204         if (!indio_dev)
 205                 return -ENOMEM;
 206
 207         adc = iio_priv(indio_dev);
 208         adc->spi = spi;
 209         mutex_init(&adc->lock);
 210
 211         if (id->driver_data == max1118) {
 212                 adc->reg = devm_regulator_get(&spi->dev, "vref");
 213                 if (IS_ERR(adc->reg)) {
 214                         dev_err(&spi->dev, "failed to get vref regulator\n");
 215                         return PTR_ERR(adc->reg);
 216                 }
 217                 ret = regulator_enable(adc->reg);
 218                 if (ret)
 219                         return ret;
 220         }
 221
 222         spi_set_drvdata(spi, indio_dev);
 223
 224         indio_dev->name = spi_get_device_id(spi)->name;
 225         indio_dev->dev.parent = &spi->dev;
 226         indio_dev->info = &max1118_info;
 227         indio_dev->modes = INDIO_DIRECT_MODE;
 228         indio_dev->channels = max1118_channels;
 229         indio_dev->num_channels = ARRAY_SIZE(max1118_channels);
 230
 231         /*
 232          * To reinitiate a conversion on CH0, it is necessary to allow for a
 233          * conversion to be complete and all of the data to be read out.  Once
 234          * a conversion has been completed, the MAX1117/MAX1118/MAX1119 will go
 235          * into AutoShutdown mode until the next conversion is initiated.
 236          */
 237         max1118_read(spi, 0);
 238
 239         ret = iio_triggered_buffer_setup(indio_dev, NULL,
 240                                         max1118_trigger_handler, NULL);
 241         if (ret)
 242                 goto err_reg_disable;
 243
 244         ret = iio_device_register(indio_dev);
 245         if (ret)
 246                 goto err_buffer_cleanup;
 247
 248         return 0;
 249
 250 err_buffer_cleanup:
 251         iio_triggered_buffer_cleanup(indio_dev);
 252 err_reg_disable:
 253         if (id->driver_data == max1118)
 254                 regulator_disable(adc->reg);
 255
 256         return ret;
 257 }
 258
 259 static int max1118_remove(struct spi_device *spi)
 260 {
 261         struct iio_dev *indio_dev = spi_get_drvdata(spi);
 262         struct max1118 *adc = iio_priv(indio_dev);
 263         const struct spi_device_id *id = spi_get_device_id(spi);
 264
 265         iio_device_unregister(indio_dev);
 266         iio_triggered_buffer_cleanup(indio_dev);
 267         if (id->driver_data == max1118)
 268                 return regulator_disable(adc->reg);
 269
 270         return 0;
 271 }
 272
 273 static const struct spi_device_id max1118_id[] = {
 274         { "max1117", max1117 },
 275         { "max1118", max1118 },
 276         { "max1119", max1119 },
 277         {}
 278 };
 279 MODULE_DEVICE_TABLE(spi, max1118_id);
 280
 281 #ifdef CONFIG_OF
 282
 283 static const struct of_device_id max1118_dt_ids[] = {
 284         { .compatible = "maxim,max1117" },
 285         { .compatible = "maxim,max1118" },
 286         { .compatible = "maxim,max1119" },
 287         {},
 288 };
 289 MODULE_DEVICE_TABLE(of, max1118_dt_ids);
 290
 291 #endif
 292
 293 static struct spi_driver max1118_spi_driver = {
 294         .driver = {
 295                 .name = "max1118",
 296                 .of_match_table = of_match_ptr(max1118_dt_ids),
 297         },
 298         .probe = max1118_probe,
 299         .remove = max1118_remove,
 300         .id_table = max1118_id,
 301 };
 302 module_spi_driver(max1118_spi_driver);
 303
 304 MODULE_AUTHOR("Akinobu Mita <akinobu.mita@gmail.com>");
 305 MODULE_DESCRIPTION("MAXIM MAX1117/MAX1118/MAX1119 ADCs driver");
 306 MODULE_LICENSE("GPL v2");