drivers/iio/adc/ad7887.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * AD7887 SPI ADC driver
   4  *
   5  * Copyright 2010-2011 Analog Devices Inc.
   6  */
   7
   8 #include <linux/device.h>
   9 #include <linux/kernel.h>
  10 #include <linux/slab.h>
  11 #include <linux/sysfs.h>
  12 #include <linux/spi/spi.h>
  13 #include <linux/regulator/consumer.h>
  14 #include <linux/err.h>
  15 #include <linux/module.h>
  16 #include <linux/interrupt.h>
  17 #include <linux/bitops.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          BIT(5)  /* on-chip reference disable */
  29 #define AD7887_DUAL             BIT(4)  /* dual-channel mode */
  30 #define AD7887_CH_AIN1          BIT(3)  /* convert on channel 1, DUAL=1 */
  31 #define AD7887_CH_AIN0          0       /* 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 /**
  44  * struct ad7887_chip_info - chip specifc information
  45  * @int_vref_mv:        the internal reference voltage
  46  * @channels:           channels specification
  47  * @num_channels:       number of channels
  48  * @dual_channels:      channels specification in dual mode
  49  * @num_dual_channels:  number of channels in dual mode
  50  */
  51 struct ad7887_chip_info {
  52         u16                             int_vref_mv;
  53         const struct iio_chan_spec      *channels;
  54         unsigned int                    num_channels;
  55         const struct iio_chan_spec      *dual_channels;
  56         unsigned int                    num_dual_channels;
  57 };
  58
  59 struct ad7887_state {
  60         struct spi_device               *spi;
  61         const struct ad7887_chip_info   *chip_info;
  62         struct regulator                *reg;
  63         struct spi_transfer             xfer[4];
  64         struct spi_message              msg[3];
  65         struct spi_message              *ring_msg;
  66         unsigned char                   tx_cmd_buf[4];
  67
  68         /*
  69          * DMA (thus cache coherency maintenance) requires the
  70          * transfer buffers to live in their own cache lines.
  71          * Buffer needs to be large enough to hold two 16 bit samples and a
  72          * 64 bit aligned 64 bit timestamp.
  73          */
  74         unsigned char data[ALIGN(4, sizeof(s64)) + sizeof(s64)]
  75                 ____cacheline_aligned;
  76 };
  77
  78 enum ad7887_supported_device_ids {
  79         ID_AD7887
  80 };
  81
  82 static int ad7887_ring_preenable(struct iio_dev *indio_dev)
  83 {
  84         struct ad7887_state *st = iio_priv(indio_dev);
  85
  86         /* We know this is a single long so can 'cheat' */
  87         switch (*indio_dev->active_scan_mask) {
  88         case (1 << 0):
  89                 st->ring_msg = &st->msg[AD7887_CH0];
  90                 break;
  91         case (1 << 1):
  92                 st->ring_msg = &st->msg[AD7887_CH1];
  93                 /* Dummy read: push CH1 setting down to hardware */
  94                 spi_sync(st->spi, st->ring_msg);
  95                 break;
  96         case ((1 << 1) | (1 << 0)):
  97                 st->ring_msg = &st->msg[AD7887_CH0_CH1];
  98                 break;
  99         }
 100
 101         return 0;
 102 }
 103
 104 static int ad7887_ring_postdisable(struct iio_dev *indio_dev)
 105 {
 106         struct ad7887_state *st = iio_priv(indio_dev);
 107
 108         /* dummy read: restore default CH0 settin */
 109         return spi_sync(st->spi, &st->msg[AD7887_CH0]);
 110 }
 111
 112 /**
 113  * ad7887_trigger_handler() bh of trigger launched polling to ring buffer
 114  *
 115  * Currently there is no option in this driver to disable the saving of
 116  * timestamps within the ring.
 117  **/
 118 static irqreturn_t ad7887_trigger_handler(int irq, void *p)
 119 {
 120         struct iio_poll_func *pf = p;
 121         struct iio_dev *indio_dev = pf->indio_dev;
 122         struct ad7887_state *st = iio_priv(indio_dev);
 123         int b_sent;
 124
 125         b_sent = spi_sync(st->spi, st->ring_msg);
 126         if (b_sent)
 127                 goto done;
 128
 129         iio_push_to_buffers_with_timestamp(indio_dev, st->data,
 130                 iio_get_time_ns(indio_dev));
 131 done:
 132         iio_trigger_notify_done(indio_dev->trig);
 133
 134         return IRQ_HANDLED;
 135 }
 136
 137 static const struct iio_buffer_setup_ops ad7887_ring_setup_ops = {
 138         .preenable = &ad7887_ring_preenable,
 139         .postenable = &iio_triggered_buffer_postenable,
 140         .predisable = &iio_triggered_buffer_predisable,
 141         .postdisable = &ad7887_ring_postdisable,
 142 };
 143
 144 static int ad7887_scan_direct(struct ad7887_state *st, unsigned ch)
 145 {
 146         int ret = spi_sync(st->spi, &st->msg[ch]);
 147         if (ret)
 148                 return ret;
 149
 150         return (st->data[(ch * 2)] << 8) | st->data[(ch * 2) + 1];
 151 }
 152
 153 static int ad7887_read_raw(struct iio_dev *indio_dev,
 154                            struct iio_chan_spec const *chan,
 155                            int *val,
 156                            int *val2,
 157                            long m)
 158 {
 159         int ret;
 160         struct ad7887_state *st = iio_priv(indio_dev);
 161
 162         switch (m) {
 163         case IIO_CHAN_INFO_RAW:
 164                 ret = iio_device_claim_direct_mode(indio_dev);
 165                 if (ret)
 166                         return ret;
 167                 ret = ad7887_scan_direct(st, chan->address);
 168                 iio_device_release_direct_mode(indio_dev);
 169
 170                 if (ret < 0)
 171                         return ret;
 172                 *val = ret >> chan->scan_type.shift;
 173                 *val &= GENMASK(chan->scan_type.realbits - 1, 0);
 174                 return IIO_VAL_INT;
 175         case IIO_CHAN_INFO_SCALE:
 176                 if (st->reg) {
 177                         *val = regulator_get_voltage(st->reg);
 178                         if (*val < 0)
 179                                 return *val;
 180                         *val /= 1000;
 181                 } else {
 182                         *val = st->chip_info->int_vref_mv;
 183                 }
 184
 185                 *val2 = chan->scan_type.realbits;
 186
 187                 return IIO_VAL_FRACTIONAL_LOG2;
 188         }
 189         return -EINVAL;
 190 }
 191
 192 #define AD7887_CHANNEL(x) { \
 193         .type = IIO_VOLTAGE, \
 194         .indexed = 1, \
 195         .channel = (x), \
 196         .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
 197         .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
 198         .address = (x), \
 199         .scan_index = (x), \
 200         .scan_type = { \
 201                 .sign = 'u', \
 202                 .realbits = 12, \
 203                 .storagebits = 16, \
 204                 .shift = 0, \
 205                 .endianness = IIO_BE, \
 206         }, \
 207 }
 208
 209 static const struct iio_chan_spec ad7887_channels[] = {
 210         AD7887_CHANNEL(0),
 211         IIO_CHAN_SOFT_TIMESTAMP(1),
 212 };
 213
 214 static const struct iio_chan_spec ad7887_dual_channels[] = {
 215         AD7887_CHANNEL(0),
 216         AD7887_CHANNEL(1),
 217         IIO_CHAN_SOFT_TIMESTAMP(2),
 218 };
 219
 220 static const struct ad7887_chip_info ad7887_chip_info_tbl[] = {
 221         /*
 222          * More devices added in future
 223          */
 224         [ID_AD7887] = {
 225                 .channels = ad7887_channels,
 226                 .num_channels = ARRAY_SIZE(ad7887_channels),
 227                 .dual_channels = ad7887_dual_channels,
 228                 .num_dual_channels = ARRAY_SIZE(ad7887_dual_channels),
 229                 .int_vref_mv = 2500,
 230         },
 231 };
 232
 233 static const struct iio_info ad7887_info = {
 234         .read_raw = &ad7887_read_raw,
 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->dev.of_node = spi->dev.of_node;
 270         indio_dev->name = spi_get_device_id(spi)->name;
 271         indio_dev->info = &ad7887_info;
 272         indio_dev->modes = INDIO_DIRECT_MODE;
 273
 274         /* Setup default message */
 275
 276         mode = AD7887_PM_MODE4;
 277         if (!pdata || !pdata->use_onchip_ref)
 278                 mode |= AD7887_REF_DIS;
 279         if (pdata && pdata->en_dual)
 280                 mode |= AD7887_DUAL;
 281
 282         st->tx_cmd_buf[0] = AD7887_CH_AIN0 | mode;
 283
 284         st->xfer[0].rx_buf = &st->data[0];
 285         st->xfer[0].tx_buf = &st->tx_cmd_buf[0];
 286         st->xfer[0].len = 2;
 287
 288         spi_message_init(&st->msg[AD7887_CH0]);
 289         spi_message_add_tail(&st->xfer[0], &st->msg[AD7887_CH0]);
 290
 291         if (pdata && pdata->en_dual) {
 292                 st->tx_cmd_buf[2] = AD7887_CH_AIN1 | mode;
 293
 294                 st->xfer[1].rx_buf = &st->data[0];
 295                 st->xfer[1].tx_buf = &st->tx_cmd_buf[2];
 296                 st->xfer[1].len = 2;
 297
 298                 st->xfer[2].rx_buf = &st->data[2];
 299                 st->xfer[2].tx_buf = &st->tx_cmd_buf[0];
 300                 st->xfer[2].len = 2;
 301
 302                 spi_message_init(&st->msg[AD7887_CH0_CH1]);
 303                 spi_message_add_tail(&st->xfer[1], &st->msg[AD7887_CH0_CH1]);
 304                 spi_message_add_tail(&st->xfer[2], &st->msg[AD7887_CH0_CH1]);
 305
 306                 st->xfer[3].rx_buf = &st->data[2];
 307                 st->xfer[3].tx_buf = &st->tx_cmd_buf[2];
 308                 st->xfer[3].len = 2;
 309
 310                 spi_message_init(&st->msg[AD7887_CH1]);
 311                 spi_message_add_tail(&st->xfer[3], &st->msg[AD7887_CH1]);
 312
 313                 indio_dev->channels = st->chip_info->dual_channels;
 314                 indio_dev->num_channels = st->chip_info->num_dual_channels;
 315         } else {
 316                 indio_dev->channels = st->chip_info->channels;
 317                 indio_dev->num_channels = st->chip_info->num_channels;
 318         }
 319
 320         ret = iio_triggered_buffer_setup(indio_dev, &iio_pollfunc_store_time,
 321                         &ad7887_trigger_handler, &ad7887_ring_setup_ops);
 322         if (ret)
 323                 goto error_disable_reg;
 324
 325         ret = iio_device_register(indio_dev);
 326         if (ret)
 327                 goto error_unregister_ring;
 328
 329         return 0;
 330 error_unregister_ring:
 331         iio_triggered_buffer_cleanup(indio_dev);
 332 error_disable_reg:
 333         if (st->reg)
 334                 regulator_disable(st->reg);
 335
 336         return ret;
 337 }
 338
 339 static int ad7887_remove(struct spi_device *spi)
 340 {
 341         struct iio_dev *indio_dev = spi_get_drvdata(spi);
 342         struct ad7887_state *st = iio_priv(indio_dev);
 343
 344         iio_device_unregister(indio_dev);
 345         iio_triggered_buffer_cleanup(indio_dev);
 346         if (st->reg)
 347                 regulator_disable(st->reg);
 348
 349         return 0;
 350 }
 351
 352 static const struct spi_device_id ad7887_id[] = {
 353         {"ad7887", ID_AD7887},
 354         {}
 355 };
 356 MODULE_DEVICE_TABLE(spi, ad7887_id);
 357
 358 static struct spi_driver ad7887_driver = {
 359         .driver = {
 360                 .name   = "ad7887",
 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 <michael.hennerich@analog.com>");
 369 MODULE_DESCRIPTION("Analog Devices AD7887 ADC");
 370 MODULE_LICENSE("GPL v2");