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         /* Buffer used to align data */
  32         struct {
  33                 __be16 channels[4];
  34                 s64 ts __aligned(8);
  35         } scan;
  36         /*
  37          * DMA (thus cache coherency maintenance) requires the
  38          * transfer buffers to live in their own cache line.
  39          */
  40         u16 tx_buf[4] ____cacheline_aligned;
  41         __be16 rx_buf[5]; /* First 16-bits are trash */
  42 };
  43
  44 #define ADC084S021_VOLTAGE_CHANNEL(num)                  \
  45         {                                                      \
  46                 .type = IIO_VOLTAGE,                                 \
  47                 .channel = (num),                                    \
  48                 .indexed = 1,                                        \
  49                 .scan_index = (num),                                 \
  50                 .scan_type = {                                       \
  51                         .sign = 'u',                                       \
  52                         .realbits = 8,                                     \
  53                         .storagebits = 16,                                 \
  54                         .shift = 4,                                        \
  55                         .endianness = IIO_BE,                              \
  56                 },                                                   \
  57                 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),        \
  58                 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),\
  59         }
  60
  61 static const struct iio_chan_spec adc084s021_channels[] = {
  62         ADC084S021_VOLTAGE_CHANNEL(0),
  63         ADC084S021_VOLTAGE_CHANNEL(1),
  64         ADC084S021_VOLTAGE_CHANNEL(2),
  65         ADC084S021_VOLTAGE_CHANNEL(3),
  66         IIO_CHAN_SOFT_TIMESTAMP(4),
  67 };
  68
  69 /**
  70  * Read an ADC channel and return its value.
  71  *
  72  * @adc: The ADC SPI data.
  73  * @data: Buffer for converted data.
  74  */
  75 static int adc084s021_adc_conversion(struct adc084s021 *adc, void *data)
  76 {
  77         int n_words = (adc->spi_trans.len >> 1) - 1; /* Discard first word */
  78         int ret, i = 0;
  79         u16 *p = data;
  80
  81         /* Do the transfer */
  82         ret = spi_sync(adc->spi, &adc->message);
  83         if (ret < 0)
  84                 return ret;
  85
  86         for (; i < n_words; i++)
  87                 *(p + i) = adc->rx_buf[i + 1];
  88
  89         return ret;
  90 }
  91
  92 static int adc084s021_read_raw(struct iio_dev *indio_dev,
  93                            struct iio_chan_spec const *channel, int *val,
  94                            int *val2, long mask)
  95 {
  96         struct adc084s021 *adc = iio_priv(indio_dev);
  97         int ret;
  98
  99         switch (mask) {
 100         case IIO_CHAN_INFO_RAW:
 101                 ret = iio_device_claim_direct_mode(indio_dev);
 102                 if (ret < 0)
 103                         return ret;
 104
 105                 ret = regulator_enable(adc->reg);
 106                 if (ret) {
 107                         iio_device_release_direct_mode(indio_dev);
 108                         return ret;
 109                 }
 110
 111                 adc->tx_buf[0] = channel->channel << 3;
 112                 ret = adc084s021_adc_conversion(adc, val);
 113                 iio_device_release_direct_mode(indio_dev);
 114                 regulator_disable(adc->reg);
 115                 if (ret < 0)
 116                         return ret;
 117
 118                 *val = be16_to_cpu(*val);
 119                 *val = (*val >> channel->scan_type.shift) & 0xff;
 120
 121                 return IIO_VAL_INT;
 122         case IIO_CHAN_INFO_SCALE:
 123                 ret = regulator_enable(adc->reg);
 124                 if (ret)
 125                         return ret;
 126
 127                 ret = regulator_get_voltage(adc->reg);
 128                 regulator_disable(adc->reg);
 129                 if (ret < 0)
 130                         return ret;
 131
 132                 *val = ret / 1000;
 133
 134                 return IIO_VAL_INT;
 135         default:
 136                 return -EINVAL;
 137         }
 138 }
 139
 140 /**
 141  * Read enabled ADC channels and push data to the buffer.
 142  *
 143  * @irq: The interrupt number (not used).
 144  * @pollfunc: Pointer to the poll func.
 145  */
 146 static irqreturn_t adc084s021_buffer_trigger_handler(int irq, void *pollfunc)
 147 {
 148         struct iio_poll_func *pf = pollfunc;
 149         struct iio_dev *indio_dev = pf->indio_dev;
 150         struct adc084s021 *adc = iio_priv(indio_dev);
 151
 152         mutex_lock(&adc->lock);
 153
 154         if (adc084s021_adc_conversion(adc, adc->scan.channels) < 0)
 155                 dev_err(&adc->spi->dev, "Failed to read data\n");
 156
 157         iio_push_to_buffers_with_timestamp(indio_dev, &adc->scan,
 158                                            iio_get_time_ns(indio_dev));
 159         mutex_unlock(&adc->lock);
 160         iio_trigger_notify_done(indio_dev->trig);
 161
 162         return IRQ_HANDLED;
 163 }
 164
 165 static int adc084s021_buffer_preenable(struct iio_dev *indio_dev)
 166 {
 167         struct adc084s021 *adc = iio_priv(indio_dev);
 168         int scan_index;
 169         int i = 0;
 170
 171         for_each_set_bit(scan_index, indio_dev->active_scan_mask,
 172                          indio_dev->masklength) {
 173                 const struct iio_chan_spec *channel =
 174                         &indio_dev->channels[scan_index];
 175                 adc->tx_buf[i++] = channel->channel << 3;
 176         }
 177         adc->spi_trans.len = 2 + (i * sizeof(__be16)); /* Trash + channels */
 178
 179         return regulator_enable(adc->reg);
 180 }
 181
 182 static int adc084s021_buffer_postdisable(struct iio_dev *indio_dev)
 183 {
 184         struct adc084s021 *adc = iio_priv(indio_dev);
 185
 186         adc->spi_trans.len = 4; /* Trash + single channel */
 187
 188         return regulator_disable(adc->reg);
 189 }
 190
 191 static const struct iio_info adc084s021_info = {
 192         .read_raw = adc084s021_read_raw,
 193 };
 194
 195 static const struct iio_buffer_setup_ops adc084s021_buffer_setup_ops = {
 196         .preenable = adc084s021_buffer_preenable,
 197         .postenable = iio_triggered_buffer_postenable,
 198         .predisable = iio_triggered_buffer_predisable,
 199         .postdisable = adc084s021_buffer_postdisable,
 200 };
 201
 202 static int adc084s021_probe(struct spi_device *spi)
 203 {
 204         struct iio_dev *indio_dev;
 205         struct adc084s021 *adc;
 206         int ret;
 207
 208         indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*adc));
 209         if (!indio_dev) {
 210                 dev_err(&spi->dev, "Failed to allocate IIO device\n");
 211                 return -ENOMEM;
 212         }
 213
 214         adc = iio_priv(indio_dev);
 215         adc->spi = spi;
 216
 217         /* Connect the SPI device and the iio dev */
 218         spi_set_drvdata(spi, indio_dev);
 219
 220         /* Initiate the Industrial I/O device */
 221         indio_dev->dev.parent = &spi->dev;
 222         indio_dev->dev.of_node = spi->dev.of_node;
 223         indio_dev->name = spi_get_device_id(spi)->name;
 224         indio_dev->modes = INDIO_DIRECT_MODE;
 225         indio_dev->info = &adc084s021_info;
 226         indio_dev->channels = adc084s021_channels;
 227         indio_dev->num_channels = ARRAY_SIZE(adc084s021_channels);
 228
 229         /* Create SPI transfer for channel reads */
 230         adc->spi_trans.tx_buf = adc->tx_buf;
 231         adc->spi_trans.rx_buf = adc->rx_buf;
 232         adc->spi_trans.len = 4; /* Trash + single channel */
 233         spi_message_init_with_transfers(&adc->message, &adc->spi_trans, 1);
 234
 235         adc->reg = devm_regulator_get(&spi->dev, "vref");
 236         if (IS_ERR(adc->reg))
 237                 return PTR_ERR(adc->reg);
 238
 239         mutex_init(&adc->lock);
 240
 241         /* Setup triggered buffer with pollfunction */
 242         ret = devm_iio_triggered_buffer_setup(&spi->dev, indio_dev, NULL,
 243                                             adc084s021_buffer_trigger_handler,
 244                                             &adc084s021_buffer_setup_ops);
 245         if (ret) {
 246                 dev_err(&spi->dev, "Failed to setup triggered buffer\n");
 247                 return ret;
 248         }
 249
 250         return devm_iio_device_register(&spi->dev, indio_dev);
 251 }
 252
 253 static const struct of_device_id adc084s021_of_match[] = {
 254         { .compatible = "ti,adc084s021", },
 255         {},
 256 };
 257 MODULE_DEVICE_TABLE(of, adc084s021_of_match);
 258
 259 static const struct spi_device_id adc084s021_id[] = {
 260         { ADC084S021_DRIVER_NAME, 0},
 261         {}
 262 };
 263 MODULE_DEVICE_TABLE(spi, adc084s021_id);
 264
 265 static struct spi_driver adc084s021_driver = {
 266         .driver = {
 267                 .name = ADC084S021_DRIVER_NAME,
 268                 .of_match_table = of_match_ptr(adc084s021_of_match),
 269         },
 270         .probe = adc084s021_probe,
 271         .id_table = adc084s021_id,
 272 };
 273 module_spi_driver(adc084s021_driver);
 274
 275 MODULE_AUTHOR("Mårten Lindahl <martenli@axis.com>");
 276 MODULE_DESCRIPTION("Texas Instruments ADC084S021");
 277 MODULE_LICENSE("GPL v2");
 278 MODULE_VERSION("1.0");