drivers/iio/adc/max1118.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * MAX1117/MAX1118/MAX1119 8-bit, dual-channel ADCs driver
   4  *
   5  * Copyright (c) 2017 Akinobu Mita <akinobu.mita@gmail.com>
   6  *
   7  * Datasheet: https://datasheets.maximintegrated.com/en/ds/MAX1117-MAX1119.pdf
   8  *
   9  * SPI interface connections
  10  *
  11  * SPI                MAXIM
  12  * Master  Direction  MAX1117/8/9
  13  * ------  ---------  -----------
  14  * nCS        -->     CNVST
  15  * SCK        -->     SCLK
  16  * MISO       <--     DOUT
  17  * ------  ---------  -----------
  18  */
  19
  20 #include <linux/module.h>
  21 #include <linux/mod_devicetable.h>
  22 #include <linux/spi/spi.h>
  23 #include <linux/iio/iio.h>
  24 #include <linux/iio/buffer.h>
  25 #include <linux/iio/triggered_buffer.h>
  26 #include <linux/iio/trigger_consumer.h>
  27 #include <linux/regulator/consumer.h>
  28
  29 enum max1118_id {
  30         max1117,
  31         max1118,
  32         max1119,
  33 };
  34
  35 struct max1118 {
  36         struct spi_device *spi;
  37         struct mutex lock;
  38         struct regulator *reg;
  39         /* Ensure natural alignment of buffer elements */
  40         struct {
  41                 u8 channels[2];
  42                 s64 ts __aligned(8);
  43         } scan;
  44
  45         u8 data ____cacheline_aligned;
  46 };
  47
  48 #define MAX1118_CHANNEL(ch)                                             \
  49         {                                                               \
  50                 .type = IIO_VOLTAGE,                                    \
  51                 .indexed = 1,                                           \
  52                 .channel = (ch),                                        \
  53                 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),           \
  54                 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),   \
  55                 .scan_index = ch,                                       \
  56                 .scan_type = {                                          \
  57                         .sign = 'u',                                    \
  58                         .realbits = 8,                                  \
  59                         .storagebits = 8,                               \
  60                 },                                                      \
  61         }
  62
  63 static const struct iio_chan_spec max1118_channels[] = {
  64         MAX1118_CHANNEL(0),
  65         MAX1118_CHANNEL(1),
  66         IIO_CHAN_SOFT_TIMESTAMP(2),
  67 };
  68
  69 static int max1118_read(struct spi_device *spi, int channel)
  70 {
  71         struct iio_dev *indio_dev = spi_get_drvdata(spi);
  72         struct max1118 *adc = iio_priv(indio_dev);
  73         struct spi_transfer xfers[] = {
  74                 /*
  75                  * To select CH1 for conversion, CNVST pin must be brought high
  76                  * and low for a second time.
  77                  */
  78                 {
  79                         .len = 0,
  80                         .delay = {      /* > CNVST Low Time 100 ns */
  81                                 .value = 1,
  82                                 .unit = SPI_DELAY_UNIT_USECS
  83                         },
  84                         .cs_change = 1,
  85                 },
  86                 /*
  87                  * The acquisition interval begins with the falling edge of
  88                  * CNVST.  The total acquisition and conversion process takes
  89                  * <7.5us.
  90                  */
  91                 {
  92                         .len = 0,
  93                         .delay = {
  94                                 .value = 8,
  95                                 .unit = SPI_DELAY_UNIT_USECS
  96                         },
  97                 },
  98                 {
  99                         .rx_buf = &adc->data,
 100                         .len = 1,
 101                 },
 102         };
 103         int ret;
 104
 105         if (channel == 0)
 106                 ret = spi_sync_transfer(spi, xfers + 1, 2);
 107         else
 108                 ret = spi_sync_transfer(spi, xfers, 3);
 109
 110         if (ret)
 111                 return ret;
 112
 113         return adc->data;
 114 }
 115
 116 static int max1118_get_vref_mV(struct spi_device *spi)
 117 {
 118         struct iio_dev *indio_dev = spi_get_drvdata(spi);
 119         struct max1118 *adc = iio_priv(indio_dev);
 120         const struct spi_device_id *id = spi_get_device_id(spi);
 121         int vref_uV;
 122
 123         switch (id->driver_data) {
 124         case max1117:
 125                 return 2048;
 126         case max1119:
 127                 return 4096;
 128         case max1118:
 129                 vref_uV = regulator_get_voltage(adc->reg);
 130                 if (vref_uV < 0)
 131                         return vref_uV;
 132                 return vref_uV / 1000;
 133         }
 134
 135         return -ENODEV;
 136 }
 137
 138 static int max1118_read_raw(struct iio_dev *indio_dev,
 139                         struct iio_chan_spec const *chan,
 140                         int *val, int *val2, long mask)
 141 {
 142         struct max1118 *adc = iio_priv(indio_dev);
 143
 144         switch (mask) {
 145         case IIO_CHAN_INFO_RAW:
 146                 mutex_lock(&adc->lock);
 147                 *val = max1118_read(adc->spi, chan->channel);
 148                 mutex_unlock(&adc->lock);
 149                 if (*val < 0)
 150                         return *val;
 151
 152                 return IIO_VAL_INT;
 153         case IIO_CHAN_INFO_SCALE:
 154                 *val = max1118_get_vref_mV(adc->spi);
 155                 if (*val < 0)
 156                         return *val;
 157                 *val2 = 8;
 158
 159                 return IIO_VAL_FRACTIONAL_LOG2;
 160         }
 161
 162         return -EINVAL;
 163 }
 164
 165 static const struct iio_info max1118_info = {
 166         .read_raw = max1118_read_raw,
 167 };
 168
 169 static irqreturn_t max1118_trigger_handler(int irq, void *p)
 170 {
 171         struct iio_poll_func *pf = p;
 172         struct iio_dev *indio_dev = pf->indio_dev;
 173         struct max1118 *adc = iio_priv(indio_dev);
 174         int scan_index;
 175         int i = 0;
 176
 177         mutex_lock(&adc->lock);
 178
 179         for_each_set_bit(scan_index, indio_dev->active_scan_mask,
 180                         indio_dev->masklength) {
 181                 const struct iio_chan_spec *scan_chan =
 182                                 &indio_dev->channels[scan_index];
 183                 int ret = max1118_read(adc->spi, scan_chan->channel);
 184
 185                 if (ret < 0) {
 186                         dev_warn(&adc->spi->dev,
 187                                 "failed to get conversion data\n");
 188                         goto out;
 189                 }
 190
 191                 adc->scan.channels[i] = ret;
 192                 i++;
 193         }
 194         iio_push_to_buffers_with_timestamp(indio_dev, &adc->scan,
 195                                            iio_get_time_ns(indio_dev));
 196 out:
 197         mutex_unlock(&adc->lock);
 198
 199         iio_trigger_notify_done(indio_dev->trig);
 200
 201         return IRQ_HANDLED;
 202 }
 203
 204 static int max1118_probe(struct spi_device *spi)
 205 {
 206         struct iio_dev *indio_dev;
 207         struct max1118 *adc;
 208         const struct spi_device_id *id = spi_get_device_id(spi);
 209         int ret;
 210
 211         indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*adc));
 212         if (!indio_dev)
 213                 return -ENOMEM;
 214
 215         adc = iio_priv(indio_dev);
 216         adc->spi = spi;
 217         mutex_init(&adc->lock);
 218
 219         if (id->driver_data == max1118) {
 220                 adc->reg = devm_regulator_get(&spi->dev, "vref");
 221                 if (IS_ERR(adc->reg)) {
 222                         dev_err(&spi->dev, "failed to get vref regulator\n");
 223                         return PTR_ERR(adc->reg);
 224                 }
 225                 ret = regulator_enable(adc->reg);
 226                 if (ret)
 227                         return ret;
 228         }
 229
 230         spi_set_drvdata(spi, indio_dev);
 231
 232         indio_dev->name = spi_get_device_id(spi)->name;
 233         indio_dev->info = &max1118_info;
 234         indio_dev->modes = INDIO_DIRECT_MODE;
 235         indio_dev->channels = max1118_channels;
 236         indio_dev->num_channels = ARRAY_SIZE(max1118_channels);
 237
 238         /*
 239          * To reinitiate a conversion on CH0, it is necessary to allow for a
 240          * conversion to be complete and all of the data to be read out.  Once
 241          * a conversion has been completed, the MAX1117/MAX1118/MAX1119 will go
 242          * into AutoShutdown mode until the next conversion is initiated.
 243          */
 244         max1118_read(spi, 0);
 245
 246         ret = iio_triggered_buffer_setup(indio_dev, NULL,
 247                                         max1118_trigger_handler, NULL);
 248         if (ret)
 249                 goto err_reg_disable;
 250
 251         ret = iio_device_register(indio_dev);
 252         if (ret)
 253                 goto err_buffer_cleanup;
 254
 255         return 0;
 256
 257 err_buffer_cleanup:
 258         iio_triggered_buffer_cleanup(indio_dev);
 259 err_reg_disable:
 260         if (id->driver_data == max1118)
 261                 regulator_disable(adc->reg);
 262
 263         return ret;
 264 }
 265
 266 static int max1118_remove(struct spi_device *spi)
 267 {
 268         struct iio_dev *indio_dev = spi_get_drvdata(spi);
 269         struct max1118 *adc = iio_priv(indio_dev);
 270         const struct spi_device_id *id = spi_get_device_id(spi);
 271
 272         iio_device_unregister(indio_dev);
 273         iio_triggered_buffer_cleanup(indio_dev);
 274         if (id->driver_data == max1118)
 275                 return regulator_disable(adc->reg);
 276
 277         return 0;
 278 }
 279
 280 static const struct spi_device_id max1118_id[] = {
 281         { "max1117", max1117 },
 282         { "max1118", max1118 },
 283         { "max1119", max1119 },
 284         {}
 285 };
 286 MODULE_DEVICE_TABLE(spi, max1118_id);
 287
 288 static const struct of_device_id max1118_dt_ids[] = {
 289         { .compatible = "maxim,max1117" },
 290         { .compatible = "maxim,max1118" },
 291         { .compatible = "maxim,max1119" },
 292         {},
 293 };
 294 MODULE_DEVICE_TABLE(of, max1118_dt_ids);
 295
 296 static struct spi_driver max1118_spi_driver = {
 297         .driver = {
 298                 .name = "max1118",
 299                 .of_match_table = max1118_dt_ids,
 300         },
 301         .probe = max1118_probe,
 302         .remove = max1118_remove,
 303         .id_table = max1118_id,
 304 };
 305 module_spi_driver(max1118_spi_driver);
 306
 307 MODULE_AUTHOR("Akinobu Mita <akinobu.mita@gmail.com>");
 308 MODULE_DESCRIPTION("MAXIM MAX1117/MAX1118/MAX1119 ADCs driver");
 309 MODULE_LICENSE("GPL v2");