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 __aligned(IIO_DMA_MINALIGN);
  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 iio_dev *indio_dev, int channel)
  70 {
  71         struct max1118 *adc = iio_priv(indio_dev);
  72         struct spi_transfer xfers[] = {
  73                 /*
  74                  * To select CH1 for conversion, CNVST pin must be brought high
  75                  * and low for a second time.
  76                  */
  77                 {
  78                         .len = 0,
  79                         .delay = {      /* > CNVST Low Time 100 ns */
  80                                 .value = 1,
  81                                 .unit = SPI_DELAY_UNIT_USECS
  82                         },
  83                         .cs_change = 1,
  84                 },
  85                 /*
  86                  * The acquisition interval begins with the falling edge of
  87                  * CNVST.  The total acquisition and conversion process takes
  88                  * <7.5us.
  89                  */
  90                 {
  91                         .len = 0,
  92                         .delay = {
  93                                 .value = 8,
  94                                 .unit = SPI_DELAY_UNIT_USECS
  95                         },
  96                 },
  97                 {
  98                         .rx_buf = &adc->data,
  99                         .len = 1,
 100                 },
 101         };
 102         int ret;
 103
 104         if (channel == 0)
 105                 ret = spi_sync_transfer(adc->spi, xfers + 1, 2);
 106         else
 107                 ret = spi_sync_transfer(adc->spi, xfers, 3);
 108
 109         if (ret)
 110                 return ret;
 111
 112         return adc->data;
 113 }
 114
 115 static int max1118_get_vref_mV(struct iio_dev *indio_dev)
 116 {
 117         struct max1118 *adc = iio_priv(indio_dev);
 118         const struct spi_device_id *id = spi_get_device_id(adc->spi);
 119         int vref_uV;
 120
 121         switch (id->driver_data) {
 122         case max1117:
 123                 return 2048;
 124         case max1119:
 125                 return 4096;
 126         case max1118:
 127                 vref_uV = regulator_get_voltage(adc->reg);
 128                 if (vref_uV < 0)
 129                         return vref_uV;
 130                 return vref_uV / 1000;
 131         }
 132
 133         return -ENODEV;
 134 }
 135
 136 static int max1118_read_raw(struct iio_dev *indio_dev,
 137                         struct iio_chan_spec const *chan,
 138                         int *val, int *val2, long mask)
 139 {
 140         struct max1118 *adc = iio_priv(indio_dev);
 141
 142         switch (mask) {
 143         case IIO_CHAN_INFO_RAW:
 144                 mutex_lock(&adc->lock);
 145                 *val = max1118_read(indio_dev, chan->channel);
 146                 mutex_unlock(&adc->lock);
 147                 if (*val < 0)
 148                         return *val;
 149
 150                 return IIO_VAL_INT;
 151         case IIO_CHAN_INFO_SCALE:
 152                 *val = max1118_get_vref_mV(indio_dev);
 153                 if (*val < 0)
 154                         return *val;
 155                 *val2 = 8;
 156
 157                 return IIO_VAL_FRACTIONAL_LOG2;
 158         }
 159
 160         return -EINVAL;
 161 }
 162
 163 static const struct iio_info max1118_info = {
 164         .read_raw = max1118_read_raw,
 165 };
 166
 167 static irqreturn_t max1118_trigger_handler(int irq, void *p)
 168 {
 169         struct iio_poll_func *pf = p;
 170         struct iio_dev *indio_dev = pf->indio_dev;
 171         struct max1118 *adc = iio_priv(indio_dev);
 172         int scan_index;
 173         int i = 0;
 174
 175         mutex_lock(&adc->lock);
 176
 177         iio_for_each_active_channel(indio_dev, scan_index) {
 178                 const struct iio_chan_spec *scan_chan =
 179                                 &indio_dev->channels[scan_index];
 180                 int ret = max1118_read(indio_dev, scan_chan->channel);
 181
 182                 if (ret < 0) {
 183                         dev_warn(&adc->spi->dev,
 184                                 "failed to get conversion data\n");
 185                         goto out;
 186                 }
 187
 188                 adc->scan.channels[i] = ret;
 189                 i++;
 190         }
 191         iio_push_to_buffers_with_timestamp(indio_dev, &adc->scan,
 192                                            iio_get_time_ns(indio_dev));
 193 out:
 194         mutex_unlock(&adc->lock);
 195
 196         iio_trigger_notify_done(indio_dev->trig);
 197
 198         return IRQ_HANDLED;
 199 }
 200
 201 static void max1118_reg_disable(void *reg)
 202 {
 203         regulator_disable(reg);
 204 }
 205
 206 static int max1118_probe(struct spi_device *spi)
 207 {
 208         struct iio_dev *indio_dev;
 209         struct max1118 *adc;
 210         const struct spi_device_id *id = spi_get_device_id(spi);
 211         int ret;
 212
 213         indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*adc));
 214         if (!indio_dev)
 215                 return -ENOMEM;
 216
 217         adc = iio_priv(indio_dev);
 218         adc->spi = spi;
 219         mutex_init(&adc->lock);
 220
 221         if (id->driver_data == max1118) {
 222                 adc->reg = devm_regulator_get(&spi->dev, "vref");
 223                 if (IS_ERR(adc->reg))
 224                         return dev_err_probe(&spi->dev, PTR_ERR(adc->reg),
 225                                              "failed to get vref regulator\n");
 226                 ret = regulator_enable(adc->reg);
 227                 if (ret)
 228                         return ret;
 229
 230                 ret = devm_add_action_or_reset(&spi->dev, max1118_reg_disable,
 231                                                adc->reg);
 232                 if (ret)
 233                         return ret;
 234
 235         }
 236
 237         indio_dev->name = spi_get_device_id(spi)->name;
 238         indio_dev->info = &max1118_info;
 239         indio_dev->modes = INDIO_DIRECT_MODE;
 240         indio_dev->channels = max1118_channels;
 241         indio_dev->num_channels = ARRAY_SIZE(max1118_channels);
 242
 243         /*
 244          * To reinitiate a conversion on CH0, it is necessary to allow for a
 245          * conversion to be complete and all of the data to be read out.  Once
 246          * a conversion has been completed, the MAX1117/MAX1118/MAX1119 will go
 247          * into AutoShutdown mode until the next conversion is initiated.
 248          */
 249         max1118_read(indio_dev, 0);
 250
 251         ret = devm_iio_triggered_buffer_setup(&spi->dev, indio_dev, NULL,
 252                                               max1118_trigger_handler, NULL);
 253         if (ret)
 254                 return ret;
 255
 256         return devm_iio_device_register(&spi->dev, indio_dev);
 257 }
 258
 259 static const struct spi_device_id max1118_id[] = {
 260         { "max1117", max1117 },
 261         { "max1118", max1118 },
 262         { "max1119", max1119 },
 263         { }
 264 };
 265 MODULE_DEVICE_TABLE(spi, max1118_id);
 266
 267 static const struct of_device_id max1118_dt_ids[] = {
 268         { .compatible = "maxim,max1117" },
 269         { .compatible = "maxim,max1118" },
 270         { .compatible = "maxim,max1119" },
 271         { }
 272 };
 273 MODULE_DEVICE_TABLE(of, max1118_dt_ids);
 274
 275 static struct spi_driver max1118_spi_driver = {
 276         .driver = {
 277                 .name = "max1118",
 278                 .of_match_table = max1118_dt_ids,
 279         },
 280         .probe = max1118_probe,
 281         .id_table = max1118_id,
 282 };
 283 module_spi_driver(max1118_spi_driver);
 284
 285 MODULE_AUTHOR("Akinobu Mita <akinobu.mita@gmail.com>");
 286 MODULE_DESCRIPTION("MAXIM MAX1117/MAX1118/MAX1119 ADCs driver");
 287 MODULE_LICENSE("GPL v2");