drivers/iio/adc/ad7887.c

   1 /*
   2  * AD7887 SPI ADC driver
   3  *
   4  * Copyright 2010-2011 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/module.h>
  17 #include <linux/interrupt.h>
  18 #include <linux/bitops.h>
  19
  20 #include <linux/iio/iio.h>
  21 #include <linux/iio/sysfs.h>
  22 #include <linux/iio/buffer.h>
  23
  24 #include <linux/iio/trigger_consumer.h>
  25 #include <linux/iio/triggered_buffer.h>
  26
  27 #include <linux/platform_data/ad7887.h>
  28
  29 #define AD7887_REF_DIS          BIT(5)  /* on-chip reference disable */
  30 #define AD7887_DUAL             BIT(4)  /* dual-channel mode */
  31 #define AD7887_CH_AIN1          BIT(3)  /* convert on channel 1, DUAL=1 */
  32 #define AD7887_CH_AIN0          0       /* convert on channel 0, DUAL=0,1 */
  33 #define AD7887_PM_MODE1         0       /* CS based shutdown */
  34 #define AD7887_PM_MODE2         1       /* full on */
  35 #define AD7887_PM_MODE3         2       /* auto shutdown after conversion */
  36 #define AD7887_PM_MODE4         3       /* standby mode */
  37
  38 enum ad7887_channels {
  39         AD7887_CH0,
  40         AD7887_CH0_CH1,
  41         AD7887_CH1,
  42 };
  43
  44 /**
  45  * struct ad7887_chip_info - chip specifc information
  46  * @int_vref_mv:        the internal reference voltage
  47  * @channel:            channel specification
  48  */
  49 struct ad7887_chip_info {
  50         u16                             int_vref_mv;
  51         struct iio_chan_spec            channel[3];
  52 };
  53
  54 struct ad7887_state {
  55         struct spi_device               *spi;
  56         const struct ad7887_chip_info   *chip_info;
  57         struct regulator                *reg;
  58         struct spi_transfer             xfer[4];
  59         struct spi_message              msg[3];
  60         struct spi_message              *ring_msg;
  61         unsigned char                   tx_cmd_buf[4];
  62
  63         /*
  64          * DMA (thus cache coherency maintenance) requires the
  65          * transfer buffers to live in their own cache lines.
  66          * Buffer needs to be large enough to hold two 16 bit samples and a
  67          * 64 bit aligned 64 bit timestamp.
  68          */
  69         unsigned char data[ALIGN(4, sizeof(s64)) + sizeof(s64)]
  70                 ____cacheline_aligned;
  71 };
  72
  73 enum ad7887_supported_device_ids {
  74         ID_AD7887
  75 };
  76
  77 static int ad7887_ring_preenable(struct iio_dev *indio_dev)
  78 {
  79         struct ad7887_state *st = iio_priv(indio_dev);
  80
  81         /* We know this is a single long so can 'cheat' */
  82         switch (*indio_dev->active_scan_mask) {
  83         case (1 << 0):
  84                 st->ring_msg = &st->msg[AD7887_CH0];
  85                 break;
  86         case (1 << 1):
  87                 st->ring_msg = &st->msg[AD7887_CH1];
  88                 /* Dummy read: push CH1 setting down to hardware */
  89                 spi_sync(st->spi, st->ring_msg);
  90                 break;
  91         case ((1 << 1) | (1 << 0)):
  92                 st->ring_msg = &st->msg[AD7887_CH0_CH1];
  93                 break;
  94         }
  95
  96         return 0;
  97 }
  98
  99 static int ad7887_ring_postdisable(struct iio_dev *indio_dev)
 100 {
 101         struct ad7887_state *st = iio_priv(indio_dev);
 102
 103         /* dummy read: restore default CH0 settin */
 104         return spi_sync(st->spi, &st->msg[AD7887_CH0]);
 105 }
 106
 107 /**
 108  * ad7887_trigger_handler() bh of trigger launched polling to ring buffer
 109  *
 110  * Currently there is no option in this driver to disable the saving of
 111  * timestamps within the ring.
 112  **/
 113 static irqreturn_t ad7887_trigger_handler(int irq, void *p)
 114 {
 115         struct iio_poll_func *pf = p;
 116         struct iio_dev *indio_dev = pf->indio_dev;
 117         struct ad7887_state *st = iio_priv(indio_dev);
 118         int b_sent;
 119
 120         b_sent = spi_sync(st->spi, st->ring_msg);
 121         if (b_sent)
 122                 goto done;
 123
 124         iio_push_to_buffers_with_timestamp(indio_dev, st->data,
 125                 iio_get_time_ns(indio_dev));
 126 done:
 127         iio_trigger_notify_done(indio_dev->trig);
 128
 129         return IRQ_HANDLED;
 130 }
 131
 132 static const struct iio_buffer_setup_ops ad7887_ring_setup_ops = {
 133         .preenable = &ad7887_ring_preenable,
 134         .postenable = &iio_triggered_buffer_postenable,
 135         .predisable = &iio_triggered_buffer_predisable,
 136         .postdisable = &ad7887_ring_postdisable,
 137 };
 138
 139 static int ad7887_scan_direct(struct ad7887_state *st, unsigned ch)
 140 {
 141         int ret = spi_sync(st->spi, &st->msg[ch]);
 142         if (ret)
 143                 return ret;
 144
 145         return (st->data[(ch * 2)] << 8) | st->data[(ch * 2) + 1];
 146 }
 147
 148 static int ad7887_read_raw(struct iio_dev *indio_dev,
 149                            struct iio_chan_spec const *chan,
 150                            int *val,
 151                            int *val2,
 152                            long m)
 153 {
 154         int ret;
 155         struct ad7887_state *st = iio_priv(indio_dev);
 156
 157         switch (m) {
 158         case IIO_CHAN_INFO_RAW:
 159                 ret = iio_device_claim_direct_mode(indio_dev);
 160                 if (ret)
 161                         return ret;
 162                 ret = ad7887_scan_direct(st, chan->address);
 163                 iio_device_release_direct_mode(indio_dev);
 164
 165                 if (ret < 0)
 166                         return ret;
 167                 *val = ret >> chan->scan_type.shift;
 168                 *val &= GENMASK(chan->scan_type.realbits - 1, 0);
 169                 return IIO_VAL_INT;
 170         case IIO_CHAN_INFO_SCALE:
 171                 if (st->reg) {
 172                         *val = regulator_get_voltage(st->reg);
 173                         if (*val < 0)
 174                                 return *val;
 175                         *val /= 1000;
 176                 } else {
 177                         *val = st->chip_info->int_vref_mv;
 178                 }
 179
 180                 *val2 = chan->scan_type.realbits;
 181
 182                 return IIO_VAL_FRACTIONAL_LOG2;
 183         }
 184         return -EINVAL;
 185 }
 186
 187
 188 static const struct ad7887_chip_info ad7887_chip_info_tbl[] = {
 189         /*
 190          * More devices added in future
 191          */
 192         [ID_AD7887] = {
 193                 .channel[0] = {
 194                         .type = IIO_VOLTAGE,
 195                         .indexed = 1,
 196                         .channel = 1,
 197                         .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
 198                         .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),
 199                         .address = 1,
 200                         .scan_index = 1,
 201                         .scan_type = {
 202                                 .sign = 'u',
 203                                 .realbits = 12,
 204                                 .storagebits = 16,
 205                                 .shift = 0,
 206                                 .endianness = IIO_BE,
 207                         },
 208                 },
 209                 .channel[1] = {
 210                         .type = IIO_VOLTAGE,
 211                         .indexed = 1,
 212                         .channel = 0,
 213                         .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
 214                         .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),
 215                         .address = 0,
 216                         .scan_index = 0,
 217                         .scan_type = {
 218                                 .sign = 'u',
 219                                 .realbits = 12,
 220                                 .storagebits = 16,
 221                                 .shift = 0,
 222                                 .endianness = IIO_BE,
 223                         },
 224                 },
 225                 .channel[2] = IIO_CHAN_SOFT_TIMESTAMP(2),
 226                 .int_vref_mv = 2500,
 227         },
 228 };
 229
 230 static const struct iio_info ad7887_info = {
 231         .read_raw = &ad7887_read_raw,
 232 };
 233
 234 static int ad7887_probe(struct spi_device *spi)
 235 {
 236         struct ad7887_platform_data *pdata = spi->dev.platform_data;
 237         struct ad7887_state *st;
 238         struct iio_dev *indio_dev;
 239         uint8_t mode;
 240         int ret;
 241
 242         indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
 243         if (indio_dev == NULL)
 244                 return -ENOMEM;
 245
 246         st = iio_priv(indio_dev);
 247
 248         if (!pdata || !pdata->use_onchip_ref) {
 249                 st->reg = devm_regulator_get(&spi->dev, "vref");
 250                 if (IS_ERR(st->reg))
 251                         return PTR_ERR(st->reg);
 252
 253                 ret = regulator_enable(st->reg);
 254                 if (ret)
 255                         return ret;
 256         }
 257
 258         st->chip_info =
 259                 &ad7887_chip_info_tbl[spi_get_device_id(spi)->driver_data];
 260
 261         spi_set_drvdata(spi, indio_dev);
 262         st->spi = spi;
 263
 264         /* Estabilish that the iio_dev is a child of the spi device */
 265         indio_dev->dev.parent = &spi->dev;
 266         indio_dev->dev.of_node = spi->dev.of_node;
 267         indio_dev->name = spi_get_device_id(spi)->name;
 268         indio_dev->info = &ad7887_info;
 269         indio_dev->modes = INDIO_DIRECT_MODE;
 270
 271         /* Setup default message */
 272
 273         mode = AD7887_PM_MODE4;
 274         if (!pdata || !pdata->use_onchip_ref)
 275                 mode |= AD7887_REF_DIS;
 276         if (pdata && pdata->en_dual)
 277                 mode |= AD7887_DUAL;
 278
 279         st->tx_cmd_buf[0] = AD7887_CH_AIN0 | mode;
 280
 281         st->xfer[0].rx_buf = &st->data[0];
 282         st->xfer[0].tx_buf = &st->tx_cmd_buf[0];
 283         st->xfer[0].len = 2;
 284
 285         spi_message_init(&st->msg[AD7887_CH0]);
 286         spi_message_add_tail(&st->xfer[0], &st->msg[AD7887_CH0]);
 287
 288         if (pdata && pdata->en_dual) {
 289                 st->tx_cmd_buf[2] = AD7887_CH_AIN1 | mode;
 290
 291                 st->xfer[1].rx_buf = &st->data[0];
 292                 st->xfer[1].tx_buf = &st->tx_cmd_buf[2];
 293                 st->xfer[1].len = 2;
 294
 295                 st->xfer[2].rx_buf = &st->data[2];
 296                 st->xfer[2].tx_buf = &st->tx_cmd_buf[0];
 297                 st->xfer[2].len = 2;
 298
 299                 spi_message_init(&st->msg[AD7887_CH0_CH1]);
 300                 spi_message_add_tail(&st->xfer[1], &st->msg[AD7887_CH0_CH1]);
 301                 spi_message_add_tail(&st->xfer[2], &st->msg[AD7887_CH0_CH1]);
 302
 303                 st->xfer[3].rx_buf = &st->data[2];
 304                 st->xfer[3].tx_buf = &st->tx_cmd_buf[2];
 305                 st->xfer[3].len = 2;
 306
 307                 spi_message_init(&st->msg[AD7887_CH1]);
 308                 spi_message_add_tail(&st->xfer[3], &st->msg[AD7887_CH1]);
 309
 310                 indio_dev->channels = st->chip_info->channel;
 311                 indio_dev->num_channels = 3;
 312         } else {
 313                 indio_dev->channels = &st->chip_info->channel[1];
 314                 indio_dev->num_channels = 2;
 315         }
 316
 317         ret = iio_triggered_buffer_setup(indio_dev, &iio_pollfunc_store_time,
 318                         &ad7887_trigger_handler, &ad7887_ring_setup_ops);
 319         if (ret)
 320                 goto error_disable_reg;
 321
 322         ret = iio_device_register(indio_dev);
 323         if (ret)
 324                 goto error_unregister_ring;
 325
 326         return 0;
 327 error_unregister_ring:
 328         iio_triggered_buffer_cleanup(indio_dev);
 329 error_disable_reg:
 330         if (st->reg)
 331                 regulator_disable(st->reg);
 332
 333         return ret;
 334 }
 335
 336 static int ad7887_remove(struct spi_device *spi)
 337 {
 338         struct iio_dev *indio_dev = spi_get_drvdata(spi);
 339         struct ad7887_state *st = iio_priv(indio_dev);
 340
 341         iio_device_unregister(indio_dev);
 342         iio_triggered_buffer_cleanup(indio_dev);
 343         if (st->reg)
 344                 regulator_disable(st->reg);
 345
 346         return 0;
 347 }
 348
 349 static const struct spi_device_id ad7887_id[] = {
 350         {"ad7887", ID_AD7887},
 351         {}
 352 };
 353 MODULE_DEVICE_TABLE(spi, ad7887_id);
 354
 355 static struct spi_driver ad7887_driver = {
 356         .driver = {
 357                 .name   = "ad7887",
 358         },
 359         .probe          = ad7887_probe,
 360         .remove         = ad7887_remove,
 361         .id_table       = ad7887_id,
 362 };
 363 module_spi_driver(ad7887_driver);
 364
 365 MODULE_AUTHOR("Michael Hennerich <michael.hennerich@analog.com>");
 366 MODULE_DESCRIPTION("Analog Devices AD7887 ADC");
 367 MODULE_LICENSE("GPL v2");