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