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