drivers/iio/adc/ad7923.c

   1 /*
   2  * AD7923 SPI ADC driver
   3  *
   4  * Copyright 2011 Analog Devices Inc (from AD7923 Driver)
   5  * Copyright 2012 CS Systemes d'Information
   6  *
   7  * Licensed under the GPL-2.
   8  */
   9
  10 #include <linux/device.h>
  11 #include <linux/kernel.h>
  12 #include <linux/slab.h>
  13 #include <linux/sysfs.h>
  14 #include <linux/spi/spi.h>
  15 #include <linux/regulator/consumer.h>
  16 #include <linux/err.h>
  17 #include <linux/delay.h>
  18 #include <linux/module.h>
  19 #include <linux/interrupt.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 #define AD7923_WRITE_CR         (1 << 11)       /* write control register */
  28 #define AD7923_RANGE            (1 << 1)        /* range to REFin */
  29 #define AD7923_CODING           (1 << 0)        /* coding is straight binary */
  30 #define AD7923_PM_MODE_AS       (1)             /* auto shutdown */
  31 #define AD7923_PM_MODE_FS       (2)             /* full shutdown */
  32 #define AD7923_PM_MODE_OPS      (3)             /* normal operation */
  33 #define AD7923_CHANNEL_0        (0)             /* analog input 0 */
  34 #define AD7923_CHANNEL_1        (1)             /* analog input 1 */
  35 #define AD7923_CHANNEL_2        (2)             /* analog input 2 */
  36 #define AD7923_CHANNEL_3        (3)             /* analog input 3 */
  37 #define AD7923_SEQUENCE_OFF     (0)             /* no sequence fonction */
  38 #define AD7923_SEQUENCE_PROTECT (2)             /* no interrupt write cycle */
  39 #define AD7923_SEQUENCE_ON      (3)             /* continuous sequence */
  40
  41 #define AD7923_MAX_CHAN         4
  42
  43 #define AD7923_PM_MODE_WRITE(mode)      (mode << 4)     /* write mode */
  44 #define AD7923_CHANNEL_WRITE(channel)   (channel << 6)  /* write channel */
  45 #define AD7923_SEQUENCE_WRITE(sequence) (((sequence & 1) << 3) \
  46                                         + ((sequence & 2) << 9))
  47                                                 /* write sequence fonction */
  48 /* left shift for CR : bit 11 transmit in first */
  49 #define AD7923_SHIFT_REGISTER   4
  50
  51 /* val = value, dec = left shift, bits = number of bits of the mask */
  52 #define EXTRACT(val, dec, bits)         ((val >> dec) & ((1 << bits) - 1))
  53
  54 struct ad7923_state {
  55         struct spi_device               *spi;
  56         struct spi_transfer             ring_xfer[5];
  57         struct spi_transfer             scan_single_xfer[2];
  58         struct spi_message              ring_msg;
  59         struct spi_message              scan_single_msg;
  60
  61         struct regulator                *reg;
  62
  63         unsigned int                    settings;
  64
  65         /*
  66          * DMA (thus cache coherency maintenance) requires the
  67          * transfer buffers to live in their own cache lines.
  68          */
  69         __be16                          rx_buf[4] ____cacheline_aligned;
  70         __be16                          tx_buf[4];
  71 };
  72
  73 #define AD7923_V_CHAN(index)                                            \
  74         {                                                               \
  75                 .type = IIO_VOLTAGE,                                    \
  76                 .indexed = 1,                                           \
  77                 .channel = index,                                       \
  78                 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),           \
  79                 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),   \
  80                 .address = index,                                       \
  81                 .scan_index = index,                                    \
  82                 .scan_type = {                                          \
  83                         .sign = 'u',                                    \
  84                         .realbits = 12,                                 \
  85                         .storagebits = 16,                              \
  86                         .endianness = IIO_BE,                           \
  87                 },                                                      \
  88         }
  89
  90 static const struct iio_chan_spec ad7923_channels[] = {
  91         AD7923_V_CHAN(0),
  92         AD7923_V_CHAN(1),
  93         AD7923_V_CHAN(2),
  94         AD7923_V_CHAN(3),
  95         IIO_CHAN_SOFT_TIMESTAMP(4),
  96 };
  97
  98 /**
  99  * ad7923_update_scan_mode() setup the spi transfer buffer for the new scan mask
 100  **/
 101 static int ad7923_update_scan_mode(struct iio_dev *indio_dev,
 102         const unsigned long *active_scan_mask)
 103 {
 104         struct ad7923_state *st = iio_priv(indio_dev);
 105         int i, cmd, len;
 106
 107         len = 0;
 108         for_each_set_bit(i, active_scan_mask, AD7923_MAX_CHAN) {
 109                 cmd = AD7923_WRITE_CR | AD7923_CHANNEL_WRITE(i) |
 110                         AD7923_SEQUENCE_WRITE(AD7923_SEQUENCE_OFF) |
 111                         st->settings;
 112                 cmd <<= AD7923_SHIFT_REGISTER;
 113                 st->tx_buf[len++] = cpu_to_be16(cmd);
 114         }
 115         /* build spi ring message */
 116         st->ring_xfer[0].tx_buf = &st->tx_buf[0];
 117         st->ring_xfer[0].len = len;
 118         st->ring_xfer[0].cs_change = 1;
 119
 120         spi_message_init(&st->ring_msg);
 121         spi_message_add_tail(&st->ring_xfer[0], &st->ring_msg);
 122
 123         for (i = 0; i < len; i++) {
 124                 st->ring_xfer[i + 1].rx_buf = &st->rx_buf[i];
 125                 st->ring_xfer[i + 1].len = 2;
 126                 st->ring_xfer[i + 1].cs_change = 1;
 127                 spi_message_add_tail(&st->ring_xfer[i + 1], &st->ring_msg);
 128         }
 129         /* make sure last transfer cs_change is not set */
 130         st->ring_xfer[i + 1].cs_change = 0;
 131
 132         return 0;
 133 }
 134
 135 /**
 136  * ad7923_trigger_handler() bh of trigger launched polling to ring buffer
 137  *
 138  * Currently there is no option in this driver to disable the saving of
 139  * timestamps within the ring.
 140  **/
 141 static irqreturn_t ad7923_trigger_handler(int irq, void *p)
 142 {
 143         struct iio_poll_func *pf = p;
 144         struct iio_dev *indio_dev = pf->indio_dev;
 145         struct ad7923_state *st = iio_priv(indio_dev);
 146         s64 time_ns = 0;
 147         int b_sent;
 148
 149         b_sent = spi_sync(st->spi, &st->ring_msg);
 150         if (b_sent)
 151                 goto done;
 152
 153         if (indio_dev->scan_timestamp) {
 154                 time_ns = iio_get_time_ns();
 155                 memcpy((u8 *)st->rx_buf + indio_dev->scan_bytes - sizeof(s64),
 156                         &time_ns, sizeof(time_ns));
 157         }
 158
 159         iio_push_to_buffers(indio_dev, (u8 *)st->rx_buf);
 160
 161 done:
 162         iio_trigger_notify_done(indio_dev->trig);
 163
 164         return IRQ_HANDLED;
 165 }
 166
 167 static int ad7923_scan_direct(struct ad7923_state *st, unsigned ch)
 168 {
 169         int ret, cmd;
 170
 171         cmd = AD7923_WRITE_CR | AD7923_CHANNEL_WRITE(ch) |
 172                 AD7923_SEQUENCE_WRITE(AD7923_SEQUENCE_OFF) |
 173                 st->settings;
 174         cmd <<= AD7923_SHIFT_REGISTER;
 175         st->tx_buf[0] = cpu_to_be16(cmd);
 176
 177         ret = spi_sync(st->spi, &st->scan_single_msg);
 178         if (ret)
 179                 return ret;
 180
 181         return be16_to_cpu(st->rx_buf[0]);
 182 }
 183
 184 static int ad7923_get_range(struct ad7923_state *st)
 185 {
 186         int vref;
 187
 188         vref = regulator_get_voltage(st->reg);
 189         if (vref < 0)
 190                 return vref;
 191
 192         vref /= 1000;
 193
 194         if (!(st->settings & AD7923_RANGE))
 195                 vref *= 2;
 196
 197         return vref;
 198 }
 199
 200 static int ad7923_read_raw(struct iio_dev *indio_dev,
 201                            struct iio_chan_spec const *chan,
 202                            int *val,
 203                            int *val2,
 204                            long m)
 205 {
 206         int ret;
 207         struct ad7923_state *st = iio_priv(indio_dev);
 208
 209         switch (m) {
 210         case IIO_CHAN_INFO_RAW:
 211                 mutex_lock(&indio_dev->mlock);
 212                 if (iio_buffer_enabled(indio_dev))
 213                         ret = -EBUSY;
 214                 else
 215                         ret = ad7923_scan_direct(st, chan->address);
 216                 mutex_unlock(&indio_dev->mlock);
 217
 218                 if (ret < 0)
 219                         return ret;
 220
 221                 if (chan->address == EXTRACT(ret, 12, 4))
 222                         *val = EXTRACT(ret, 0, 12);
 223                 else
 224                         return -EIO;
 225
 226                 return IIO_VAL_INT;
 227         case IIO_CHAN_INFO_SCALE:
 228                 ret = ad7923_get_range(st);
 229                 if (ret < 0)
 230                         return ret;
 231                 *val = ret;
 232                 *val2 = chan->scan_type.realbits;
 233                 return IIO_VAL_FRACTIONAL_LOG2;
 234         }
 235         return -EINVAL;
 236 }
 237
 238 static const struct iio_info ad7923_info = {
 239         .read_raw = &ad7923_read_raw,
 240         .update_scan_mode = ad7923_update_scan_mode,
 241         .driver_module = THIS_MODULE,
 242 };
 243
 244 static int ad7923_probe(struct spi_device *spi)
 245 {
 246         struct ad7923_state *st;
 247         struct iio_dev *indio_dev = iio_device_alloc(sizeof(*st));
 248         int ret;
 249
 250         if (indio_dev == NULL)
 251                 return -ENOMEM;
 252
 253         st = iio_priv(indio_dev);
 254
 255         spi_set_drvdata(spi, indio_dev);
 256
 257         st->spi = spi;
 258         st->settings = AD7923_CODING | AD7923_RANGE |
 259                         AD7923_PM_MODE_WRITE(AD7923_PM_MODE_OPS);
 260
 261         indio_dev->name = spi_get_device_id(spi)->name;
 262         indio_dev->dev.parent = &spi->dev;
 263         indio_dev->modes = INDIO_DIRECT_MODE;
 264         indio_dev->channels = ad7923_channels;
 265         indio_dev->num_channels = ARRAY_SIZE(ad7923_channels);
 266         indio_dev->info = &ad7923_info;
 267
 268         /* Setup default message */
 269
 270         st->scan_single_xfer[0].tx_buf = &st->tx_buf[0];
 271         st->scan_single_xfer[0].len = 2;
 272         st->scan_single_xfer[0].cs_change = 1;
 273         st->scan_single_xfer[1].rx_buf = &st->rx_buf[0];
 274         st->scan_single_xfer[1].len = 2;
 275
 276         spi_message_init(&st->scan_single_msg);
 277         spi_message_add_tail(&st->scan_single_xfer[0], &st->scan_single_msg);
 278         spi_message_add_tail(&st->scan_single_xfer[1], &st->scan_single_msg);
 279
 280         st->reg = regulator_get(&spi->dev, "refin");
 281         if (IS_ERR(st->reg)) {
 282                 ret = PTR_ERR(st->reg);
 283                 goto error_free;
 284         }
 285         ret = regulator_enable(st->reg);
 286         if (ret)
 287                 goto error_put_reg;
 288
 289         ret = iio_triggered_buffer_setup(indio_dev, NULL,
 290                         &ad7923_trigger_handler, NULL);
 291         if (ret)
 292                 goto error_disable_reg;
 293
 294         ret = iio_device_register(indio_dev);
 295         if (ret)
 296                 goto error_cleanup_ring;
 297
 298         return 0;
 299
 300 error_cleanup_ring:
 301         iio_triggered_buffer_cleanup(indio_dev);
 302 error_disable_reg:
 303         regulator_disable(st->reg);
 304 error_put_reg:
 305         regulator_put(st->reg);
 306 error_free:
 307         iio_device_free(indio_dev);
 308
 309         return ret;
 310 }
 311
 312 static int ad7923_remove(struct spi_device *spi)
 313 {
 314         struct iio_dev *indio_dev = spi_get_drvdata(spi);
 315         struct ad7923_state *st = iio_priv(indio_dev);
 316
 317         iio_device_unregister(indio_dev);
 318         iio_triggered_buffer_cleanup(indio_dev);
 319         regulator_disable(st->reg);
 320         regulator_put(st->reg);
 321         iio_device_free(indio_dev);
 322
 323         return 0;
 324 }
 325
 326 static const struct spi_device_id ad7923_id[] = {
 327         {"ad7923", 0},
 328         {}
 329 };
 330 MODULE_DEVICE_TABLE(spi, ad7923_id);
 331
 332 static struct spi_driver ad7923_driver = {
 333         .driver = {
 334                 .name   = "ad7923",
 335                 .owner  = THIS_MODULE,
 336         },
 337         .probe          = ad7923_probe,
 338         .remove         = ad7923_remove,
 339         .id_table       = ad7923_id,
 340 };
 341 module_spi_driver(ad7923_driver);
 342
 343 MODULE_AUTHOR("Michael Hennerich <hennerich@blackfin.uclinux.org>");
 344 MODULE_AUTHOR("Patrick Vasseur <patrick.vasseur@c-s.fr>");
 345 MODULE_DESCRIPTION("Analog Devices AD7923 ADC");
 346 MODULE_LICENSE("GPL v2");