drivers/iio/adc/ti-adc084s021.c

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