drivers/iio/adc/ad7298.c

   1 /*
   2  * AD7298 SPI ADC driver
   3  *
   4  * Copyright 2011 Analog Devices Inc.
   5  *
   6  * Licensed under the GPL-2.
   7  */
   8
   9 #include <linux/device.h>
  10 #include <linux/kernel.h>
  11 #include <linux/slab.h>
  12 #include <linux/sysfs.h>
  13 #include <linux/spi/spi.h>
  14 #include <linux/regulator/consumer.h>
  15 #include <linux/err.h>
  16 #include <linux/delay.h>
  17 #include <linux/module.h>
  18 #include <linux/interrupt.h>
  19 #include <linux/bitops.h>
  20
  21 #include <linux/iio/iio.h>
  22 #include <linux/iio/sysfs.h>
  23 #include <linux/iio/buffer.h>
  24 #include <linux/iio/trigger_consumer.h>
  25 #include <linux/iio/triggered_buffer.h>
  26
  27 #include <linux/platform_data/ad7298.h>
  28
  29 #define AD7298_WRITE    BIT(15) /* write to the control register */
  30 #define AD7298_REPEAT   BIT(14) /* repeated conversion enable */
  31 #define AD7298_CH(x)    BIT(13 - (x)) /* channel select */
  32 #define AD7298_TSENSE   BIT(5) /* temperature conversion enable */
  33 #define AD7298_EXTREF   BIT(2) /* external reference enable */
  34 #define AD7298_TAVG     BIT(1) /* temperature sensor averaging enable */
  35 #define AD7298_PDD      BIT(0) /* partial power down enable */
  36
  37 #define AD7298_MAX_CHAN         8
  38 #define AD7298_INTREF_mV        2500
  39
  40 #define AD7298_CH_TEMP          9
  41
  42 struct ad7298_state {
  43         struct spi_device               *spi;
  44         struct regulator                *reg;
  45         unsigned                        ext_ref;
  46         struct spi_transfer             ring_xfer[10];
  47         struct spi_transfer             scan_single_xfer[3];
  48         struct spi_message              ring_msg;
  49         struct spi_message              scan_single_msg;
  50         /*
  51          * DMA (thus cache coherency maintenance) requires the
  52          * transfer buffers to live in their own cache lines.
  53          */
  54         __be16                          rx_buf[12] ____cacheline_aligned;
  55         __be16                          tx_buf[2];
  56 };
  57
  58 #define AD7298_V_CHAN(index)                                            \
  59         {                                                               \
  60                 .type = IIO_VOLTAGE,                                    \
  61                 .indexed = 1,                                           \
  62                 .channel = index,                                       \
  63                 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),           \
  64                 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),   \
  65                 .address = index,                                       \
  66                 .scan_index = index,                                    \
  67                 .scan_type = {                                          \
  68                         .sign = 'u',                                    \
  69                         .realbits = 12,                                 \
  70                         .storagebits = 16,                              \
  71                         .endianness = IIO_BE,                           \
  72                 },                                                      \
  73         }
  74
  75 static const struct iio_chan_spec ad7298_channels[] = {
  76         {
  77                 .type = IIO_TEMP,
  78                 .indexed = 1,
  79                 .channel = 0,
  80                 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
  81                         BIT(IIO_CHAN_INFO_SCALE) |
  82                         BIT(IIO_CHAN_INFO_OFFSET),
  83                 .address = AD7298_CH_TEMP,
  84                 .scan_index = -1,
  85                 .scan_type = {
  86                         .sign = 's',
  87                         .realbits = 32,
  88                         .storagebits = 32,
  89                 },
  90         },
  91         AD7298_V_CHAN(0),
  92         AD7298_V_CHAN(1),
  93         AD7298_V_CHAN(2),
  94         AD7298_V_CHAN(3),
  95         AD7298_V_CHAN(4),
  96         AD7298_V_CHAN(5),
  97         AD7298_V_CHAN(6),
  98         AD7298_V_CHAN(7),
  99         IIO_CHAN_SOFT_TIMESTAMP(8),
 100 };
 101
 102 /**
 103  * ad7298_update_scan_mode() setup the spi transfer buffer for the new scan mask
 104  **/
 105 static int ad7298_update_scan_mode(struct iio_dev *indio_dev,
 106         const unsigned long *active_scan_mask)
 107 {
 108         struct ad7298_state *st = iio_priv(indio_dev);
 109         int i, m;
 110         unsigned short command;
 111         int scan_count;
 112
 113         /* Now compute overall size */
 114         scan_count = bitmap_weight(active_scan_mask, indio_dev->masklength);
 115
 116         command = AD7298_WRITE | st->ext_ref;
 117
 118         for (i = 0, m = AD7298_CH(0); i < AD7298_MAX_CHAN; i++, m >>= 1)
 119                 if (test_bit(i, active_scan_mask))
 120                         command |= m;
 121
 122         st->tx_buf[0] = cpu_to_be16(command);
 123
 124         /* build spi ring message */
 125         st->ring_xfer[0].tx_buf = &st->tx_buf[0];
 126         st->ring_xfer[0].len = 2;
 127         st->ring_xfer[0].cs_change = 1;
 128         st->ring_xfer[1].tx_buf = &st->tx_buf[1];
 129         st->ring_xfer[1].len = 2;
 130         st->ring_xfer[1].cs_change = 1;
 131
 132         spi_message_init(&st->ring_msg);
 133         spi_message_add_tail(&st->ring_xfer[0], &st->ring_msg);
 134         spi_message_add_tail(&st->ring_xfer[1], &st->ring_msg);
 135
 136         for (i = 0; i < scan_count; i++) {
 137                 st->ring_xfer[i + 2].rx_buf = &st->rx_buf[i];
 138                 st->ring_xfer[i + 2].len = 2;
 139                 st->ring_xfer[i + 2].cs_change = 1;
 140                 spi_message_add_tail(&st->ring_xfer[i + 2], &st->ring_msg);
 141         }
 142         /* make sure last transfer cs_change is not set */
 143         st->ring_xfer[i + 1].cs_change = 0;
 144
 145         return 0;
 146 }
 147
 148 /**
 149  * ad7298_trigger_handler() bh of trigger launched polling to ring buffer
 150  *
 151  * Currently there is no option in this driver to disable the saving of
 152  * timestamps within the ring.
 153  **/
 154 static irqreturn_t ad7298_trigger_handler(int irq, void *p)
 155 {
 156         struct iio_poll_func *pf = p;
 157         struct iio_dev *indio_dev = pf->indio_dev;
 158         struct ad7298_state *st = iio_priv(indio_dev);
 159         int b_sent;
 160
 161         b_sent = spi_sync(st->spi, &st->ring_msg);
 162         if (b_sent)
 163                 goto done;
 164
 165         iio_push_to_buffers_with_timestamp(indio_dev, st->rx_buf,
 166                 iio_get_time_ns());
 167
 168 done:
 169         iio_trigger_notify_done(indio_dev->trig);
 170
 171         return IRQ_HANDLED;
 172 }
 173
 174 static int ad7298_scan_direct(struct ad7298_state *st, unsigned ch)
 175 {
 176         int ret;
 177         st->tx_buf[0] = cpu_to_be16(AD7298_WRITE | st->ext_ref |
 178                                    (AD7298_CH(0) >> ch));
 179
 180         ret = spi_sync(st->spi, &st->scan_single_msg);
 181         if (ret)
 182                 return ret;
 183
 184         return be16_to_cpu(st->rx_buf[0]);
 185 }
 186
 187 static int ad7298_scan_temp(struct ad7298_state *st, int *val)
 188 {
 189         int ret;
 190         __be16 buf;
 191
 192         buf = cpu_to_be16(AD7298_WRITE | AD7298_TSENSE |
 193                           AD7298_TAVG | st->ext_ref);
 194
 195         ret = spi_write(st->spi, (u8 *)&buf, 2);
 196         if (ret)
 197                 return ret;
 198
 199         buf = cpu_to_be16(0);
 200
 201         ret = spi_write(st->spi, (u8 *)&buf, 2);
 202         if (ret)
 203                 return ret;
 204
 205         usleep_range(101, 1000); /* sleep > 100us */
 206
 207         ret = spi_read(st->spi, (u8 *)&buf, 2);
 208         if (ret)
 209                 return ret;
 210
 211         *val = sign_extend32(be16_to_cpu(buf), 11);
 212
 213         return 0;
 214 }
 215
 216 static int ad7298_get_ref_voltage(struct ad7298_state *st)
 217 {
 218         int vref;
 219
 220         if (st->ext_ref) {
 221                 vref = regulator_get_voltage(st->reg);
 222                 if (vref < 0)
 223                         return vref;
 224
 225                 return vref / 1000;
 226         } else {
 227                 return AD7298_INTREF_mV;
 228         }
 229 }
 230
 231 static int ad7298_read_raw(struct iio_dev *indio_dev,
 232                            struct iio_chan_spec const *chan,
 233                            int *val,
 234                            int *val2,
 235                            long m)
 236 {
 237         int ret;
 238         struct ad7298_state *st = iio_priv(indio_dev);
 239
 240         switch (m) {
 241         case IIO_CHAN_INFO_RAW:
 242                 mutex_lock(&indio_dev->mlock);
 243                 if (indio_dev->currentmode == INDIO_BUFFER_TRIGGERED) {
 244                         ret = -EBUSY;
 245                 } else {
 246                         if (chan->address == AD7298_CH_TEMP)
 247                                 ret = ad7298_scan_temp(st, val);
 248                         else
 249                                 ret = ad7298_scan_direct(st, chan->address);
 250                 }
 251                 mutex_unlock(&indio_dev->mlock);
 252
 253                 if (ret < 0)
 254                         return ret;
 255
 256                 if (chan->address != AD7298_CH_TEMP)
 257                         *val = ret & GENMASK(chan->scan_type.realbits - 1, 0);
 258
 259                 return IIO_VAL_INT;
 260         case IIO_CHAN_INFO_SCALE:
 261                 switch (chan->type) {
 262                 case IIO_VOLTAGE:
 263                         *val = ad7298_get_ref_voltage(st);
 264                         *val2 = chan->scan_type.realbits;
 265                         return IIO_VAL_FRACTIONAL_LOG2;
 266                 case IIO_TEMP:
 267                         *val = ad7298_get_ref_voltage(st);
 268                         *val2 = 10;
 269                         return IIO_VAL_FRACTIONAL;
 270                 default:
 271                         return -EINVAL;
 272                 }
 273         case IIO_CHAN_INFO_OFFSET:
 274                 *val = 1093 - 2732500 / ad7298_get_ref_voltage(st);
 275                 return IIO_VAL_INT;
 276         }
 277         return -EINVAL;
 278 }
 279
 280 static const struct iio_info ad7298_info = {
 281         .read_raw = &ad7298_read_raw,
 282         .update_scan_mode = ad7298_update_scan_mode,
 283         .driver_module = THIS_MODULE,
 284 };
 285
 286 static int ad7298_probe(struct spi_device *spi)
 287 {
 288         struct ad7298_platform_data *pdata = spi->dev.platform_data;
 289         struct ad7298_state *st;
 290         struct iio_dev *indio_dev;
 291         int ret;
 292
 293         indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
 294         if (indio_dev == NULL)
 295                 return -ENOMEM;
 296
 297         st = iio_priv(indio_dev);
 298
 299         if (pdata && pdata->ext_ref)
 300                 st->ext_ref = AD7298_EXTREF;
 301
 302         if (st->ext_ref) {
 303                 st->reg = devm_regulator_get(&spi->dev, "vref");
 304                 if (IS_ERR(st->reg))
 305                         return PTR_ERR(st->reg);
 306
 307                 ret = regulator_enable(st->reg);
 308                 if (ret)
 309                         return ret;
 310         }
 311
 312         spi_set_drvdata(spi, indio_dev);
 313
 314         st->spi = spi;
 315
 316         indio_dev->name = spi_get_device_id(spi)->name;
 317         indio_dev->dev.parent = &spi->dev;
 318         indio_dev->modes = INDIO_DIRECT_MODE;
 319         indio_dev->channels = ad7298_channels;
 320         indio_dev->num_channels = ARRAY_SIZE(ad7298_channels);
 321         indio_dev->info = &ad7298_info;
 322
 323         /* Setup default message */
 324
 325         st->scan_single_xfer[0].tx_buf = &st->tx_buf[0];
 326         st->scan_single_xfer[0].len = 2;
 327         st->scan_single_xfer[0].cs_change = 1;
 328         st->scan_single_xfer[1].tx_buf = &st->tx_buf[1];
 329         st->scan_single_xfer[1].len = 2;
 330         st->scan_single_xfer[1].cs_change = 1;
 331         st->scan_single_xfer[2].rx_buf = &st->rx_buf[0];
 332         st->scan_single_xfer[2].len = 2;
 333
 334         spi_message_init(&st->scan_single_msg);
 335         spi_message_add_tail(&st->scan_single_xfer[0], &st->scan_single_msg);
 336         spi_message_add_tail(&st->scan_single_xfer[1], &st->scan_single_msg);
 337         spi_message_add_tail(&st->scan_single_xfer[2], &st->scan_single_msg);
 338
 339         ret = iio_triggered_buffer_setup(indio_dev, NULL,
 340                         &ad7298_trigger_handler, NULL);
 341         if (ret)
 342                 goto error_disable_reg;
 343
 344         ret = iio_device_register(indio_dev);
 345         if (ret)
 346                 goto error_cleanup_ring;
 347
 348         return 0;
 349
 350 error_cleanup_ring:
 351         iio_triggered_buffer_cleanup(indio_dev);
 352 error_disable_reg:
 353         if (st->ext_ref)
 354                 regulator_disable(st->reg);
 355
 356         return ret;
 357 }
 358
 359 static int ad7298_remove(struct spi_device *spi)
 360 {
 361         struct iio_dev *indio_dev = spi_get_drvdata(spi);
 362         struct ad7298_state *st = iio_priv(indio_dev);
 363
 364         iio_device_unregister(indio_dev);
 365         iio_triggered_buffer_cleanup(indio_dev);
 366         if (st->ext_ref)
 367                 regulator_disable(st->reg);
 368
 369         return 0;
 370 }
 371
 372 static const struct spi_device_id ad7298_id[] = {
 373         {"ad7298", 0},
 374         {}
 375 };
 376 MODULE_DEVICE_TABLE(spi, ad7298_id);
 377
 378 static struct spi_driver ad7298_driver = {
 379         .driver = {
 380                 .name   = "ad7298",
 381                 .owner  = THIS_MODULE,
 382         },
 383         .probe          = ad7298_probe,
 384         .remove         = ad7298_remove,
 385         .id_table       = ad7298_id,
 386 };
 387 module_spi_driver(ad7298_driver);
 388
 389 MODULE_AUTHOR("Michael Hennerich <hennerich@blackfin.uclinux.org>");
 390 MODULE_DESCRIPTION("Analog Devices AD7298 ADC");
 391 MODULE_LICENSE("GPL v2");