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_separate = BIT(IIO_CHAN_INFO_RAW),           \
  67                 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),   \
  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_separate = BIT(IIO_CHAN_INFO_RAW) |
  84                         BIT(IIO_CHAN_INFO_SCALE) |
  85                         BIT(IIO_CHAN_INFO_OFFSET),
  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         int b_sent;
 163
 164         b_sent = spi_sync(st->spi, &st->ring_msg);
 165         if (b_sent)
 166                 goto done;
 167
 168         iio_push_to_buffers_with_timestamp(indio_dev, st->rx_buf,
 169                 iio_get_time_ns());
 170
 171 done:
 172         iio_trigger_notify_done(indio_dev->trig);
 173
 174         return IRQ_HANDLED;
 175 }
 176
 177 static int ad7298_scan_direct(struct ad7298_state *st, unsigned ch)
 178 {
 179         int ret;
 180         st->tx_buf[0] = cpu_to_be16(AD7298_WRITE | st->ext_ref |
 181                                    (AD7298_CH(0) >> ch));
 182
 183         ret = spi_sync(st->spi, &st->scan_single_msg);
 184         if (ret)
 185                 return ret;
 186
 187         return be16_to_cpu(st->rx_buf[0]);
 188 }
 189
 190 static int ad7298_scan_temp(struct ad7298_state *st, int *val)
 191 {
 192         int ret;
 193         __be16 buf;
 194
 195         buf = cpu_to_be16(AD7298_WRITE | AD7298_TSENSE |
 196                           AD7298_TAVG | st->ext_ref);
 197
 198         ret = spi_write(st->spi, (u8 *)&buf, 2);
 199         if (ret)
 200                 return ret;
 201
 202         buf = cpu_to_be16(0);
 203
 204         ret = spi_write(st->spi, (u8 *)&buf, 2);
 205         if (ret)
 206                 return ret;
 207
 208         usleep_range(101, 1000); /* sleep > 100us */
 209
 210         ret = spi_read(st->spi, (u8 *)&buf, 2);
 211         if (ret)
 212                 return ret;
 213
 214         *val = sign_extend32(be16_to_cpu(buf), 11);
 215
 216         return 0;
 217 }
 218
 219 static int ad7298_get_ref_voltage(struct ad7298_state *st)
 220 {
 221         int vref;
 222
 223         if (st->ext_ref) {
 224                 vref = regulator_get_voltage(st->reg);
 225                 if (vref < 0)
 226                         return vref;
 227
 228                 return vref / 1000;
 229         } else {
 230                 return AD7298_INTREF_mV;
 231         }
 232 }
 233
 234 static int ad7298_read_raw(struct iio_dev *indio_dev,
 235                            struct iio_chan_spec const *chan,
 236                            int *val,
 237                            int *val2,
 238                            long m)
 239 {
 240         int ret;
 241         struct ad7298_state *st = iio_priv(indio_dev);
 242
 243         switch (m) {
 244         case IIO_CHAN_INFO_RAW:
 245                 mutex_lock(&indio_dev->mlock);
 246                 if (indio_dev->currentmode == INDIO_BUFFER_TRIGGERED) {
 247                         ret = -EBUSY;
 248                 } else {
 249                         if (chan->address == AD7298_CH_TEMP)
 250                                 ret = ad7298_scan_temp(st, val);
 251                         else
 252                                 ret = ad7298_scan_direct(st, chan->address);
 253                 }
 254                 mutex_unlock(&indio_dev->mlock);
 255
 256                 if (ret < 0)
 257                         return ret;
 258
 259                 if (chan->address != AD7298_CH_TEMP)
 260                         *val = ret & RES_MASK(AD7298_BITS);
 261
 262                 return IIO_VAL_INT;
 263         case IIO_CHAN_INFO_SCALE:
 264                 switch (chan->type) {
 265                 case IIO_VOLTAGE:
 266                         *val = ad7298_get_ref_voltage(st);
 267                         *val2 = chan->scan_type.realbits;
 268                         return IIO_VAL_FRACTIONAL_LOG2;
 269                 case IIO_TEMP:
 270                         *val = ad7298_get_ref_voltage(st);
 271                         *val2 = 10;
 272                         return IIO_VAL_FRACTIONAL;
 273                 default:
 274                         return -EINVAL;
 275                 }
 276         case IIO_CHAN_INFO_OFFSET:
 277                 *val = 1093 - 2732500 / ad7298_get_ref_voltage(st);
 278                 return IIO_VAL_INT;
 279         }
 280         return -EINVAL;
 281 }
 282
 283 static const struct iio_info ad7298_info = {
 284         .read_raw = &ad7298_read_raw,
 285         .update_scan_mode = ad7298_update_scan_mode,
 286         .driver_module = THIS_MODULE,
 287 };
 288
 289 static int ad7298_probe(struct spi_device *spi)
 290 {
 291         struct ad7298_platform_data *pdata = spi->dev.platform_data;
 292         struct ad7298_state *st;
 293         struct iio_dev *indio_dev;
 294         int ret;
 295
 296         indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
 297         if (indio_dev == NULL)
 298                 return -ENOMEM;
 299
 300         st = iio_priv(indio_dev);
 301
 302         if (pdata && pdata->ext_ref)
 303                 st->ext_ref = AD7298_EXTREF;
 304
 305         if (st->ext_ref) {
 306                 st->reg = devm_regulator_get(&spi->dev, "vref");
 307                 if (IS_ERR(st->reg))
 308                         return PTR_ERR(st->reg);
 309
 310                 ret = regulator_enable(st->reg);
 311                 if (ret)
 312                         return ret;
 313         }
 314
 315         spi_set_drvdata(spi, indio_dev);
 316
 317         st->spi = spi;
 318
 319         indio_dev->name = spi_get_device_id(spi)->name;
 320         indio_dev->dev.parent = &spi->dev;
 321         indio_dev->modes = INDIO_DIRECT_MODE;
 322         indio_dev->channels = ad7298_channels;
 323         indio_dev->num_channels = ARRAY_SIZE(ad7298_channels);
 324         indio_dev->info = &ad7298_info;
 325
 326         /* Setup default message */
 327
 328         st->scan_single_xfer[0].tx_buf = &st->tx_buf[0];
 329         st->scan_single_xfer[0].len = 2;
 330         st->scan_single_xfer[0].cs_change = 1;
 331         st->scan_single_xfer[1].tx_buf = &st->tx_buf[1];
 332         st->scan_single_xfer[1].len = 2;
 333         st->scan_single_xfer[1].cs_change = 1;
 334         st->scan_single_xfer[2].rx_buf = &st->rx_buf[0];
 335         st->scan_single_xfer[2].len = 2;
 336
 337         spi_message_init(&st->scan_single_msg);
 338         spi_message_add_tail(&st->scan_single_xfer[0], &st->scan_single_msg);
 339         spi_message_add_tail(&st->scan_single_xfer[1], &st->scan_single_msg);
 340         spi_message_add_tail(&st->scan_single_xfer[2], &st->scan_single_msg);
 341
 342         ret = iio_triggered_buffer_setup(indio_dev, NULL,
 343                         &ad7298_trigger_handler, NULL);
 344         if (ret)
 345                 goto error_disable_reg;
 346
 347         ret = iio_device_register(indio_dev);
 348         if (ret)
 349                 goto error_cleanup_ring;
 350
 351         return 0;
 352
 353 error_cleanup_ring:
 354         iio_triggered_buffer_cleanup(indio_dev);
 355 error_disable_reg:
 356         if (st->ext_ref)
 357                 regulator_disable(st->reg);
 358
 359         return ret;
 360 }
 361
 362 static int ad7298_remove(struct spi_device *spi)
 363 {
 364         struct iio_dev *indio_dev = spi_get_drvdata(spi);
 365         struct ad7298_state *st = iio_priv(indio_dev);
 366
 367         iio_device_unregister(indio_dev);
 368         iio_triggered_buffer_cleanup(indio_dev);
 369         if (st->ext_ref)
 370                 regulator_disable(st->reg);
 371
 372         return 0;
 373 }
 374
 375 static const struct spi_device_id ad7298_id[] = {
 376         {"ad7298", 0},
 377         {}
 378 };
 379 MODULE_DEVICE_TABLE(spi, ad7298_id);
 380
 381 static struct spi_driver ad7298_driver = {
 382         .driver = {
 383                 .name   = "ad7298",
 384                 .owner  = THIS_MODULE,
 385         },
 386         .probe          = ad7298_probe,
 387         .remove         = ad7298_remove,
 388         .id_table       = ad7298_id,
 389 };
 390 module_spi_driver(ad7298_driver);
 391
 392 MODULE_AUTHOR("Michael Hennerich <hennerich@blackfin.uclinux.org>");
 393 MODULE_DESCRIPTION("Analog Devices AD7298 ADC");
 394 MODULE_LICENSE("GPL v2");