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
  20 #include <linux/iio/iio.h>
  21 #include <linux/iio/sysfs.h>
  22 #include <linux/iio/buffer.h>
  23 #include <linux/iio/trigger_consumer.h>
  24 #include <linux/iio/triggered_buffer.h>
  25
  26 #include <linux/platform_data/ad7298.h>
  27
  28 #define AD7298_WRITE    (1 << 15) /* write to the control register */
  29 #define AD7298_REPEAT   (1 << 14) /* repeated conversion enable */
  30 #define AD7298_CH(x)    (1 << (13 - (x))) /* channel select */
  31 #define AD7298_TSENSE   (1 << 5) /* temperature conversion enable */
  32 #define AD7298_EXTREF   (1 << 2) /* external reference enable */
  33 #define AD7298_TAVG     (1 << 1) /* temperature sensor averaging enable */
  34 #define AD7298_PDD      (1 << 0) /* partial power down enable */
  35
  36 #define AD7298_MAX_CHAN         8
  37 #define AD7298_BITS             12
  38 #define AD7298_STORAGE_BITS     16
  39 #define AD7298_INTREF_mV        2500
  40
  41 #define AD7298_CH_TEMP          9
  42
  43 #define RES_MASK(bits)  ((1 << (bits)) - 1)
  44
  45 struct ad7298_state {
  46         struct spi_device               *spi;
  47         struct regulator                *reg;
  48         unsigned                        ext_ref;
  49         struct spi_transfer             ring_xfer[10];
  50         struct spi_transfer             scan_single_xfer[3];
  51         struct spi_message              ring_msg;
  52         struct spi_message              scan_single_msg;
  53         /*
  54          * DMA (thus cache coherency maintenance) requires the
  55          * transfer buffers to live in their own cache lines.
  56          */
  57         __be16                          rx_buf[12] ____cacheline_aligned;
  58         __be16                          tx_buf[2];
  59 };
  60
  61 #define AD7298_V_CHAN(index)                                            \
  62         {                                                               \
  63                 .type = IIO_VOLTAGE,                                    \
  64                 .indexed = 1,                                           \
  65                 .channel = index,                                       \
  66                 .info_mask = IIO_CHAN_INFO_RAW_SEPARATE_BIT |           \
  67                 IIO_CHAN_INFO_SCALE_SHARED_BIT,                         \
  68                 .address = index,                                       \
  69                 .scan_index = index,                                    \
  70                 .scan_type = {                                          \
  71                         .sign = 'u',                                    \
  72                         .realbits = 12,                                 \
  73                         .storagebits = 16,                              \
  74                         .endianness = IIO_BE,                           \
  75                 },                                                      \
  76         }
  77
  78 static const struct iio_chan_spec ad7298_channels[] = {
  79         {
  80                 .type = IIO_TEMP,
  81                 .indexed = 1,
  82                 .channel = 0,
  83                 .info_mask = IIO_CHAN_INFO_RAW_SEPARATE_BIT |
  84                         IIO_CHAN_INFO_SCALE_SEPARATE_BIT |
  85                         IIO_CHAN_INFO_OFFSET_SEPARATE_BIT,
  86                 .address = AD7298_CH_TEMP,
  87                 .scan_index = -1,
  88                 .scan_type = {
  89                         .sign = 's',
  90                         .realbits = 32,
  91                         .storagebits = 32,
  92                 },
  93         },
  94         AD7298_V_CHAN(0),
  95         AD7298_V_CHAN(1),
  96         AD7298_V_CHAN(2),
  97         AD7298_V_CHAN(3),
  98         AD7298_V_CHAN(4),
  99         AD7298_V_CHAN(5),
 100         AD7298_V_CHAN(6),
 101         AD7298_V_CHAN(7),
 102         IIO_CHAN_SOFT_TIMESTAMP(8),
 103 };
 104
 105 /**
 106  * ad7298_update_scan_mode() setup the spi transfer buffer for the new scan mask
 107  **/
 108 static int ad7298_update_scan_mode(struct iio_dev *indio_dev,
 109         const unsigned long *active_scan_mask)
 110 {
 111         struct ad7298_state *st = iio_priv(indio_dev);
 112         int i, m;
 113         unsigned short command;
 114         int scan_count;
 115
 116         /* Now compute overall size */
 117         scan_count = bitmap_weight(active_scan_mask, indio_dev->masklength);
 118
 119         command = AD7298_WRITE | st->ext_ref;
 120
 121         for (i = 0, m = AD7298_CH(0); i < AD7298_MAX_CHAN; i++, m >>= 1)
 122                 if (test_bit(i, active_scan_mask))
 123                         command |= m;
 124
 125         st->tx_buf[0] = cpu_to_be16(command);
 126
 127         /* build spi ring message */
 128         st->ring_xfer[0].tx_buf = &st->tx_buf[0];
 129         st->ring_xfer[0].len = 2;
 130         st->ring_xfer[0].cs_change = 1;
 131         st->ring_xfer[1].tx_buf = &st->tx_buf[1];
 132         st->ring_xfer[1].len = 2;
 133         st->ring_xfer[1].cs_change = 1;
 134
 135         spi_message_init(&st->ring_msg);
 136         spi_message_add_tail(&st->ring_xfer[0], &st->ring_msg);
 137         spi_message_add_tail(&st->ring_xfer[1], &st->ring_msg);
 138
 139         for (i = 0; i < scan_count; i++) {
 140                 st->ring_xfer[i + 2].rx_buf = &st->rx_buf[i];
 141                 st->ring_xfer[i + 2].len = 2;
 142                 st->ring_xfer[i + 2].cs_change = 1;
 143                 spi_message_add_tail(&st->ring_xfer[i + 2], &st->ring_msg);
 144         }
 145         /* make sure last transfer cs_change is not set */
 146         st->ring_xfer[i + 1].cs_change = 0;
 147
 148         return 0;
 149 }
 150
 151 /**
 152  * ad7298_trigger_handler() bh of trigger launched polling to ring buffer
 153  *
 154  * Currently there is no option in this driver to disable the saving of
 155  * timestamps within the ring.
 156  **/
 157 static irqreturn_t ad7298_trigger_handler(int irq, void *p)
 158 {
 159         struct iio_poll_func *pf = p;
 160         struct iio_dev *indio_dev = pf->indio_dev;
 161         struct ad7298_state *st = iio_priv(indio_dev);
 162         s64 time_ns = 0;
 163         int b_sent;
 164
 165         b_sent = spi_sync(st->spi, &st->ring_msg);
 166         if (b_sent)
 167                 goto done;
 168
 169         if (indio_dev->scan_timestamp) {
 170                 time_ns = iio_get_time_ns();
 171                 memcpy((u8 *)st->rx_buf + indio_dev->scan_bytes - sizeof(s64),
 172                         &time_ns, sizeof(time_ns));
 173         }
 174
 175         iio_push_to_buffers(indio_dev, (u8 *)st->rx_buf);
 176
 177 done:
 178         iio_trigger_notify_done(indio_dev->trig);
 179
 180         return IRQ_HANDLED;
 181 }
 182
 183 static int ad7298_scan_direct(struct ad7298_state *st, unsigned ch)
 184 {
 185         int ret;
 186         st->tx_buf[0] = cpu_to_be16(AD7298_WRITE | st->ext_ref |
 187                                    (AD7298_CH(0) >> ch));
 188
 189         ret = spi_sync(st->spi, &st->scan_single_msg);
 190         if (ret)
 191                 return ret;
 192
 193         return be16_to_cpu(st->rx_buf[0]);
 194 }
 195
 196 static int ad7298_scan_temp(struct ad7298_state *st, int *val)
 197 {
 198         int ret;
 199         __be16 buf;
 200
 201         buf = cpu_to_be16(AD7298_WRITE | AD7298_TSENSE |
 202                           AD7298_TAVG | st->ext_ref);
 203
 204         ret = spi_write(st->spi, (u8 *)&buf, 2);
 205         if (ret)
 206                 return ret;
 207
 208         buf = cpu_to_be16(0);
 209
 210         ret = spi_write(st->spi, (u8 *)&buf, 2);
 211         if (ret)
 212                 return ret;
 213
 214         usleep_range(101, 1000); /* sleep > 100us */
 215
 216         ret = spi_read(st->spi, (u8 *)&buf, 2);
 217         if (ret)
 218                 return ret;
 219
 220         *val = sign_extend32(be16_to_cpu(buf), 11);
 221
 222         return 0;
 223 }
 224
 225 static int ad7298_get_ref_voltage(struct ad7298_state *st)
 226 {
 227         int vref;
 228
 229         if (st->ext_ref) {
 230                 vref = regulator_get_voltage(st->reg);
 231                 if (vref < 0)
 232                         return vref;
 233
 234                 return vref / 1000;
 235         } else {
 236                 return AD7298_INTREF_mV;
 237         }
 238 }
 239
 240 static int ad7298_read_raw(struct iio_dev *indio_dev,
 241                            struct iio_chan_spec const *chan,
 242                            int *val,
 243                            int *val2,
 244                            long m)
 245 {
 246         int ret;
 247         struct ad7298_state *st = iio_priv(indio_dev);
 248
 249         switch (m) {
 250         case IIO_CHAN_INFO_RAW:
 251                 mutex_lock(&indio_dev->mlock);
 252                 if (indio_dev->currentmode == INDIO_BUFFER_TRIGGERED) {
 253                         ret = -EBUSY;
 254                 } else {
 255                         if (chan->address == AD7298_CH_TEMP)
 256                                 ret = ad7298_scan_temp(st, val);
 257                         else
 258                                 ret = ad7298_scan_direct(st, chan->address);
 259                 }
 260                 mutex_unlock(&indio_dev->mlock);
 261
 262                 if (ret < 0)
 263                         return ret;
 264
 265                 if (chan->address != AD7298_CH_TEMP)
 266                         *val = ret & RES_MASK(AD7298_BITS);
 267
 268                 return IIO_VAL_INT;
 269         case IIO_CHAN_INFO_SCALE:
 270                 switch (chan->type) {
 271                 case IIO_VOLTAGE:
 272                         *val = ad7298_get_ref_voltage(st);
 273                         *val2 = chan->scan_type.realbits;
 274                         return IIO_VAL_FRACTIONAL_LOG2;
 275                 case IIO_TEMP:
 276                         *val = ad7298_get_ref_voltage(st);
 277                         *val2 = 10;
 278                         return IIO_VAL_FRACTIONAL;
 279                 default:
 280                         return -EINVAL;
 281                 }
 282         case IIO_CHAN_INFO_OFFSET:
 283                 *val = 1093 - 2732500 / ad7298_get_ref_voltage(st);
 284                 return IIO_VAL_INT;
 285         }
 286         return -EINVAL;
 287 }
 288
 289 static const struct iio_info ad7298_info = {
 290         .read_raw = &ad7298_read_raw,
 291         .update_scan_mode = ad7298_update_scan_mode,
 292         .driver_module = THIS_MODULE,
 293 };
 294
 295 static int ad7298_probe(struct spi_device *spi)
 296 {
 297         struct ad7298_platform_data *pdata = spi->dev.platform_data;
 298         struct ad7298_state *st;
 299         struct iio_dev *indio_dev = iio_device_alloc(sizeof(*st));
 300         int ret;
 301
 302         if (indio_dev == NULL)
 303                 return -ENOMEM;
 304
 305         st = iio_priv(indio_dev);
 306
 307         if (pdata && pdata->ext_ref)
 308                 st->ext_ref = AD7298_EXTREF;
 309
 310         if (st->ext_ref) {
 311                 st->reg = regulator_get(&spi->dev, "vref");
 312                 if (IS_ERR(st->reg)) {
 313                         ret = PTR_ERR(st->reg);
 314                         goto error_free;
 315                 }
 316                 ret = regulator_enable(st->reg);
 317                 if (ret)
 318                         goto error_put_reg;
 319         }
 320
 321         spi_set_drvdata(spi, indio_dev);
 322
 323         st->spi = spi;
 324
 325         indio_dev->name = spi_get_device_id(spi)->name;
 326         indio_dev->dev.parent = &spi->dev;
 327         indio_dev->modes = INDIO_DIRECT_MODE;
 328         indio_dev->channels = ad7298_channels;
 329         indio_dev->num_channels = ARRAY_SIZE(ad7298_channels);
 330         indio_dev->info = &ad7298_info;
 331
 332         /* Setup default message */
 333
 334         st->scan_single_xfer[0].tx_buf = &st->tx_buf[0];
 335         st->scan_single_xfer[0].len = 2;
 336         st->scan_single_xfer[0].cs_change = 1;
 337         st->scan_single_xfer[1].tx_buf = &st->tx_buf[1];
 338         st->scan_single_xfer[1].len = 2;
 339         st->scan_single_xfer[1].cs_change = 1;
 340         st->scan_single_xfer[2].rx_buf = &st->rx_buf[0];
 341         st->scan_single_xfer[2].len = 2;
 342
 343         spi_message_init(&st->scan_single_msg);
 344         spi_message_add_tail(&st->scan_single_xfer[0], &st->scan_single_msg);
 345         spi_message_add_tail(&st->scan_single_xfer[1], &st->scan_single_msg);
 346         spi_message_add_tail(&st->scan_single_xfer[2], &st->scan_single_msg);
 347
 348         ret = iio_triggered_buffer_setup(indio_dev, NULL,
 349                         &ad7298_trigger_handler, NULL);
 350         if (ret)
 351                 goto error_disable_reg;
 352
 353         ret = iio_device_register(indio_dev);
 354         if (ret)
 355                 goto error_cleanup_ring;
 356
 357         return 0;
 358
 359 error_cleanup_ring:
 360         iio_triggered_buffer_cleanup(indio_dev);
 361 error_disable_reg:
 362         if (st->ext_ref)
 363                 regulator_disable(st->reg);
 364 error_put_reg:
 365         if (st->ext_ref)
 366                 regulator_put(st->reg);
 367 error_free:
 368         iio_device_free(indio_dev);
 369
 370         return ret;
 371 }
 372
 373 static int ad7298_remove(struct spi_device *spi)
 374 {
 375         struct iio_dev *indio_dev = spi_get_drvdata(spi);
 376         struct ad7298_state *st = iio_priv(indio_dev);
 377
 378         iio_device_unregister(indio_dev);
 379         iio_triggered_buffer_cleanup(indio_dev);
 380         if (st->ext_ref) {
 381                 regulator_disable(st->reg);
 382                 regulator_put(st->reg);
 383         }
 384         iio_device_free(indio_dev);
 385
 386         return 0;
 387 }
 388
 389 static const struct spi_device_id ad7298_id[] = {
 390         {"ad7298", 0},
 391         {}
 392 };
 393 MODULE_DEVICE_TABLE(spi, ad7298_id);
 394
 395 static struct spi_driver ad7298_driver = {
 396         .driver = {
 397                 .name   = "ad7298",
 398                 .owner  = THIS_MODULE,
 399         },
 400         .probe          = ad7298_probe,
 401         .remove         = ad7298_remove,
 402         .id_table       = ad7298_id,
 403 };
 404 module_spi_driver(ad7298_driver);
 405
 406 MODULE_AUTHOR("Michael Hennerich <hennerich@blackfin.uclinux.org>");
 407 MODULE_DESCRIPTION("Analog Devices AD7298 ADC");
 408 MODULE_LICENSE("GPL v2");