drivers/iio/adc/ti-adc084s021.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /**
   3  * Copyright (C) 2017 Axis Communications AB
   4  *
   5  * Driver for Texas Instruments' ADC084S021 ADC chip.
   6  * Datasheets can be found here:
   7  * https://www.ti.com/lit/ds/symlink/adc084s021.pdf
   8  */
   9
  10 #include <linux/err.h>
  11 #include <linux/spi/spi.h>
  12 #include <linux/module.h>
  13 #include <linux/mod_devicetable.h>
  14 #include <linux/interrupt.h>
  15 #include <linux/iio/iio.h>
  16 #include <linux/iio/buffer.h>
  17 #include <linux/iio/triggered_buffer.h>
  18 #include <linux/iio/trigger_consumer.h>
  19 #include <linux/regulator/consumer.h>
  20
  21 #define ADC084S021_DRIVER_NAME "adc084s021"
  22
  23 struct adc084s021 {
  24         struct spi_device *spi;
  25         struct spi_message message;
  26         struct spi_transfer spi_trans;
  27         struct regulator *reg;
  28         struct mutex lock;
  29         /* Buffer used to align data */
  30         struct {
  31                 __be16 channels[4];
  32                 s64 ts __aligned(8);
  33         } scan;
  34         /*
  35          * DMA (thus cache coherency maintenance) requires the
  36          * transfer buffers to live in their own cache line.
  37          */
  38         u16 tx_buf[4] ____cacheline_aligned;
  39         __be16 rx_buf[5]; /* First 16-bits are trash */
  40 };
  41
  42 #define ADC084S021_VOLTAGE_CHANNEL(num)                  \
  43         {                                                      \
  44                 .type = IIO_VOLTAGE,                                 \
  45                 .channel = (num),                                    \
  46                 .indexed = 1,                                        \
  47                 .scan_index = (num),                                 \
  48                 .scan_type = {                                       \
  49                         .sign = 'u',                                       \
  50                         .realbits = 8,                                     \
  51                         .storagebits = 16,                                 \
  52                         .shift = 4,                                        \
  53                         .endianness = IIO_BE,                              \
  54                 },                                                   \
  55                 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),        \
  56                 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),\
  57         }
  58
  59 static const struct iio_chan_spec adc084s021_channels[] = {
  60         ADC084S021_VOLTAGE_CHANNEL(0),
  61         ADC084S021_VOLTAGE_CHANNEL(1),
  62         ADC084S021_VOLTAGE_CHANNEL(2),
  63         ADC084S021_VOLTAGE_CHANNEL(3),
  64         IIO_CHAN_SOFT_TIMESTAMP(4),
  65 };
  66
  67 /**
  68  * Read an ADC channel and return its value.
  69  *
  70  * @adc: The ADC SPI data.
  71  * @data: Buffer for converted data.
  72  */
  73 static int adc084s021_adc_conversion(struct adc084s021 *adc, void *data)
  74 {
  75         int n_words = (adc->spi_trans.len >> 1) - 1; /* Discard first word */
  76         int ret, i = 0;
  77         u16 *p = data;
  78
  79         /* Do the transfer */
  80         ret = spi_sync(adc->spi, &adc->message);
  81         if (ret < 0)
  82                 return ret;
  83
  84         for (; i < n_words; i++)
  85                 *(p + i) = adc->rx_buf[i + 1];
  86
  87         return ret;
  88 }
  89
  90 static int adc084s021_read_raw(struct iio_dev *indio_dev,
  91                            struct iio_chan_spec const *channel, int *val,
  92                            int *val2, long mask)
  93 {
  94         struct adc084s021 *adc = iio_priv(indio_dev);
  95         int ret;
  96
  97         switch (mask) {
  98         case IIO_CHAN_INFO_RAW:
  99                 ret = iio_device_claim_direct_mode(indio_dev);
 100                 if (ret < 0)
 101                         return ret;
 102
 103                 ret = regulator_enable(adc->reg);
 104                 if (ret) {
 105                         iio_device_release_direct_mode(indio_dev);
 106                         return ret;
 107                 }
 108
 109                 adc->tx_buf[0] = channel->channel << 3;
 110                 ret = adc084s021_adc_conversion(adc, val);
 111                 iio_device_release_direct_mode(indio_dev);
 112                 regulator_disable(adc->reg);
 113                 if (ret < 0)
 114                         return ret;
 115
 116                 *val = be16_to_cpu(*val);
 117                 *val = (*val >> channel->scan_type.shift) & 0xff;
 118
 119                 return IIO_VAL_INT;
 120         case IIO_CHAN_INFO_SCALE:
 121                 ret = regulator_enable(adc->reg);
 122                 if (ret)
 123                         return ret;
 124
 125                 ret = regulator_get_voltage(adc->reg);
 126                 regulator_disable(adc->reg);
 127                 if (ret < 0)
 128                         return ret;
 129
 130                 *val = ret / 1000;
 131
 132                 return IIO_VAL_INT;
 133         default:
 134                 return -EINVAL;
 135         }
 136 }
 137
 138 /**
 139  * Read enabled ADC channels and push data to the buffer.
 140  *
 141  * @irq: The interrupt number (not used).
 142  * @pollfunc: Pointer to the poll func.
 143  */
 144 static irqreturn_t adc084s021_buffer_trigger_handler(int irq, void *pollfunc)
 145 {
 146         struct iio_poll_func *pf = pollfunc;
 147         struct iio_dev *indio_dev = pf->indio_dev;
 148         struct adc084s021 *adc = iio_priv(indio_dev);
 149
 150         mutex_lock(&adc->lock);
 151
 152         if (adc084s021_adc_conversion(adc, adc->scan.channels) < 0)
 153                 dev_err(&adc->spi->dev, "Failed to read data\n");
 154
 155         iio_push_to_buffers_with_timestamp(indio_dev, &adc->scan,
 156                                            iio_get_time_ns(indio_dev));
 157         mutex_unlock(&adc->lock);
 158         iio_trigger_notify_done(indio_dev->trig);
 159
 160         return IRQ_HANDLED;
 161 }
 162
 163 static int adc084s021_buffer_preenable(struct iio_dev *indio_dev)
 164 {
 165         struct adc084s021 *adc = iio_priv(indio_dev);
 166         int scan_index;
 167         int i = 0;
 168
 169         for_each_set_bit(scan_index, indio_dev->active_scan_mask,
 170                          indio_dev->masklength) {
 171                 const struct iio_chan_spec *channel =
 172                         &indio_dev->channels[scan_index];
 173                 adc->tx_buf[i++] = channel->channel << 3;
 174         }
 175         adc->spi_trans.len = 2 + (i * sizeof(__be16)); /* Trash + channels */
 176
 177         return regulator_enable(adc->reg);
 178 }
 179
 180 static int adc084s021_buffer_postdisable(struct iio_dev *indio_dev)
 181 {
 182         struct adc084s021 *adc = iio_priv(indio_dev);
 183
 184         adc->spi_trans.len = 4; /* Trash + single channel */
 185
 186         return regulator_disable(adc->reg);
 187 }
 188
 189 static const struct iio_info adc084s021_info = {
 190         .read_raw = adc084s021_read_raw,
 191 };
 192
 193 static const struct iio_buffer_setup_ops adc084s021_buffer_setup_ops = {
 194         .preenable = adc084s021_buffer_preenable,
 195         .postdisable = adc084s021_buffer_postdisable,
 196 };
 197
 198 static int adc084s021_probe(struct spi_device *spi)
 199 {
 200         struct iio_dev *indio_dev;
 201         struct adc084s021 *adc;
 202         int ret;
 203
 204         indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*adc));
 205         if (!indio_dev) {
 206                 dev_err(&spi->dev, "Failed to allocate IIO device\n");
 207                 return -ENOMEM;
 208         }
 209
 210         adc = iio_priv(indio_dev);
 211         adc->spi = spi;
 212
 213         /* Connect the SPI device and the iio dev */
 214         spi_set_drvdata(spi, indio_dev);
 215
 216         /* Initiate the Industrial I/O device */
 217         indio_dev->name = spi_get_device_id(spi)->name;
 218         indio_dev->modes = INDIO_DIRECT_MODE;
 219         indio_dev->info = &adc084s021_info;
 220         indio_dev->channels = adc084s021_channels;
 221         indio_dev->num_channels = ARRAY_SIZE(adc084s021_channels);
 222
 223         /* Create SPI transfer for channel reads */
 224         adc->spi_trans.tx_buf = adc->tx_buf;
 225         adc->spi_trans.rx_buf = adc->rx_buf;
 226         adc->spi_trans.len = 4; /* Trash + single channel */
 227         spi_message_init_with_transfers(&adc->message, &adc->spi_trans, 1);
 228
 229         adc->reg = devm_regulator_get(&spi->dev, "vref");
 230         if (IS_ERR(adc->reg))
 231                 return PTR_ERR(adc->reg);
 232
 233         mutex_init(&adc->lock);
 234
 235         /* Setup triggered buffer with pollfunction */
 236         ret = devm_iio_triggered_buffer_setup(&spi->dev, indio_dev, NULL,
 237                                             adc084s021_buffer_trigger_handler,
 238                                             &adc084s021_buffer_setup_ops);
 239         if (ret) {
 240                 dev_err(&spi->dev, "Failed to setup triggered buffer\n");
 241                 return ret;
 242         }
 243
 244         return devm_iio_device_register(&spi->dev, indio_dev);
 245 }
 246
 247 static const struct of_device_id adc084s021_of_match[] = {
 248         { .compatible = "ti,adc084s021", },
 249         {},
 250 };
 251 MODULE_DEVICE_TABLE(of, adc084s021_of_match);
 252
 253 static const struct spi_device_id adc084s021_id[] = {
 254         { ADC084S021_DRIVER_NAME, 0},
 255         {}
 256 };
 257 MODULE_DEVICE_TABLE(spi, adc084s021_id);
 258
 259 static struct spi_driver adc084s021_driver = {
 260         .driver = {
 261                 .name = ADC084S021_DRIVER_NAME,
 262                 .of_match_table = adc084s021_of_match,
 263         },
 264         .probe = adc084s021_probe,
 265         .id_table = adc084s021_id,
 266 };
 267 module_spi_driver(adc084s021_driver);
 268
 269 MODULE_AUTHOR("Mårten Lindahl <martenli@axis.com>");
 270 MODULE_DESCRIPTION("Texas Instruments ADC084S021");
 271 MODULE_LICENSE("GPL v2");
 272 MODULE_VERSION("1.0");