drivers/iio/adc/ad7298.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * AD7298 SPI ADC driver
   4  *
   5  * Copyright 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/delay.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 #include <linux/iio/trigger_consumer.h>
  24 #include <linux/iio/triggered_buffer.h>
  25
  26 #define AD7298_WRITE    BIT(15) /* write to the control register */
  27 #define AD7298_REPEAT   BIT(14) /* repeated conversion enable */
  28 #define AD7298_CH(x)    BIT(13 - (x)) /* channel select */
  29 #define AD7298_TSENSE   BIT(5) /* temperature conversion enable */
  30 #define AD7298_EXTREF   BIT(2) /* external reference enable */
  31 #define AD7298_TAVG     BIT(1) /* temperature sensor averaging enable */
  32 #define AD7298_PDD      BIT(0) /* partial power down enable */
  33
  34 #define AD7298_MAX_CHAN         8
  35 #define AD7298_INTREF_mV        2500
  36
  37 #define AD7298_CH_TEMP          9
  38
  39 struct ad7298_state {
  40         struct spi_device               *spi;
  41         struct regulator                *reg;
  42         unsigned                        ext_ref;
  43         struct spi_transfer             ring_xfer[10];
  44         struct spi_transfer             scan_single_xfer[3];
  45         struct spi_message              ring_msg;
  46         struct spi_message              scan_single_msg;
  47         /*
  48          * DMA (thus cache coherency maintenance) requires the
  49          * transfer buffers to live in their own cache lines.
  50          */
  51         __be16                          rx_buf[12] ____cacheline_aligned;
  52         __be16                          tx_buf[2];
  53 };
  54
  55 #define AD7298_V_CHAN(index)                                            \
  56         {                                                               \
  57                 .type = IIO_VOLTAGE,                                    \
  58                 .indexed = 1,                                           \
  59                 .channel = index,                                       \
  60                 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),           \
  61                 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),   \
  62                 .address = index,                                       \
  63                 .scan_index = index,                                    \
  64                 .scan_type = {                                          \
  65                         .sign = 'u',                                    \
  66                         .realbits = 12,                                 \
  67                         .storagebits = 16,                              \
  68                         .endianness = IIO_BE,                           \
  69                 },                                                      \
  70         }
  71
  72 static const struct iio_chan_spec ad7298_channels[] = {
  73         {
  74                 .type = IIO_TEMP,
  75                 .indexed = 1,
  76                 .channel = 0,
  77                 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
  78                         BIT(IIO_CHAN_INFO_SCALE) |
  79                         BIT(IIO_CHAN_INFO_OFFSET),
  80                 .address = AD7298_CH_TEMP,
  81                 .scan_index = -1,
  82                 .scan_type = {
  83                         .sign = 's',
  84                         .realbits = 32,
  85                         .storagebits = 32,
  86                 },
  87         },
  88         AD7298_V_CHAN(0),
  89         AD7298_V_CHAN(1),
  90         AD7298_V_CHAN(2),
  91         AD7298_V_CHAN(3),
  92         AD7298_V_CHAN(4),
  93         AD7298_V_CHAN(5),
  94         AD7298_V_CHAN(6),
  95         AD7298_V_CHAN(7),
  96         IIO_CHAN_SOFT_TIMESTAMP(8),
  97 };
  98
  99 /*
 100  * ad7298_update_scan_mode() setup the spi transfer buffer for the new scan mask
 101  */
 102 static int ad7298_update_scan_mode(struct iio_dev *indio_dev,
 103         const unsigned long *active_scan_mask)
 104 {
 105         struct ad7298_state *st = iio_priv(indio_dev);
 106         int i, m;
 107         unsigned short command;
 108         int scan_count;
 109
 110         /* Now compute overall size */
 111         scan_count = bitmap_weight(active_scan_mask, indio_dev->masklength);
 112
 113         command = AD7298_WRITE | st->ext_ref;
 114
 115         for (i = 0, m = AD7298_CH(0); i < AD7298_MAX_CHAN; i++, m >>= 1)
 116                 if (test_bit(i, active_scan_mask))
 117                         command |= m;
 118
 119         st->tx_buf[0] = cpu_to_be16(command);
 120
 121         /* build spi ring message */
 122         st->ring_xfer[0].tx_buf = &st->tx_buf[0];
 123         st->ring_xfer[0].len = 2;
 124         st->ring_xfer[0].cs_change = 1;
 125         st->ring_xfer[1].tx_buf = &st->tx_buf[1];
 126         st->ring_xfer[1].len = 2;
 127         st->ring_xfer[1].cs_change = 1;
 128
 129         spi_message_init(&st->ring_msg);
 130         spi_message_add_tail(&st->ring_xfer[0], &st->ring_msg);
 131         spi_message_add_tail(&st->ring_xfer[1], &st->ring_msg);
 132
 133         for (i = 0; i < scan_count; i++) {
 134                 st->ring_xfer[i + 2].rx_buf = &st->rx_buf[i];
 135                 st->ring_xfer[i + 2].len = 2;
 136                 st->ring_xfer[i + 2].cs_change = 1;
 137                 spi_message_add_tail(&st->ring_xfer[i + 2], &st->ring_msg);
 138         }
 139         /* make sure last transfer cs_change is not set */
 140         st->ring_xfer[i + 1].cs_change = 0;
 141
 142         return 0;
 143 }
 144
 145 /*
 146  * ad7298_trigger_handler() bh of trigger launched polling to ring buffer
 147  *
 148  * Currently there is no option in this driver to disable the saving of
 149  * timestamps within the ring.
 150  */
 151 static irqreturn_t ad7298_trigger_handler(int irq, void *p)
 152 {
 153         struct iio_poll_func *pf = p;
 154         struct iio_dev *indio_dev = pf->indio_dev;
 155         struct ad7298_state *st = iio_priv(indio_dev);
 156         int b_sent;
 157
 158         b_sent = spi_sync(st->spi, &st->ring_msg);
 159         if (b_sent)
 160                 goto done;
 161
 162         iio_push_to_buffers_with_timestamp(indio_dev, st->rx_buf,
 163                 iio_get_time_ns(indio_dev));
 164
 165 done:
 166         iio_trigger_notify_done(indio_dev->trig);
 167
 168         return IRQ_HANDLED;
 169 }
 170
 171 static int ad7298_scan_direct(struct ad7298_state *st, unsigned ch)
 172 {
 173         int ret;
 174         st->tx_buf[0] = cpu_to_be16(AD7298_WRITE | st->ext_ref |
 175                                    (AD7298_CH(0) >> ch));
 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 ad7298_scan_temp(struct ad7298_state *st, int *val)
 185 {
 186         int ret;
 187         __be16 buf;
 188
 189         buf = cpu_to_be16(AD7298_WRITE | AD7298_TSENSE |
 190                           AD7298_TAVG | st->ext_ref);
 191
 192         ret = spi_write(st->spi, (u8 *)&buf, 2);
 193         if (ret)
 194                 return ret;
 195
 196         buf = cpu_to_be16(0);
 197
 198         ret = spi_write(st->spi, (u8 *)&buf, 2);
 199         if (ret)
 200                 return ret;
 201
 202         usleep_range(101, 1000); /* sleep > 100us */
 203
 204         ret = spi_read(st->spi, (u8 *)&buf, 2);
 205         if (ret)
 206                 return ret;
 207
 208         *val = sign_extend32(be16_to_cpu(buf), 11);
 209
 210         return 0;
 211 }
 212
 213 static int ad7298_get_ref_voltage(struct ad7298_state *st)
 214 {
 215         int vref;
 216
 217         if (st->reg) {
 218                 vref = regulator_get_voltage(st->reg);
 219                 if (vref < 0)
 220                         return vref;
 221
 222                 return vref / 1000;
 223         } else {
 224                 return AD7298_INTREF_mV;
 225         }
 226 }
 227
 228 static int ad7298_read_raw(struct iio_dev *indio_dev,
 229                            struct iio_chan_spec const *chan,
 230                            int *val,
 231                            int *val2,
 232                            long m)
 233 {
 234         int ret;
 235         struct ad7298_state *st = iio_priv(indio_dev);
 236
 237         switch (m) {
 238         case IIO_CHAN_INFO_RAW:
 239                 ret = iio_device_claim_direct_mode(indio_dev);
 240                 if (ret)
 241                         return ret;
 242
 243                 if (chan->address == AD7298_CH_TEMP)
 244                         ret = ad7298_scan_temp(st, val);
 245                 else
 246                         ret = ad7298_scan_direct(st, chan->address);
 247
 248                 iio_device_release_direct_mode(indio_dev);
 249
 250                 if (ret < 0)
 251                         return ret;
 252
 253                 if (chan->address != AD7298_CH_TEMP)
 254                         *val = ret & GENMASK(chan->scan_type.realbits - 1, 0);
 255
 256                 return IIO_VAL_INT;
 257         case IIO_CHAN_INFO_SCALE:
 258                 switch (chan->type) {
 259                 case IIO_VOLTAGE:
 260                         *val = ad7298_get_ref_voltage(st);
 261                         *val2 = chan->scan_type.realbits;
 262                         return IIO_VAL_FRACTIONAL_LOG2;
 263                 case IIO_TEMP:
 264                         *val = ad7298_get_ref_voltage(st);
 265                         *val2 = 10;
 266                         return IIO_VAL_FRACTIONAL;
 267                 default:
 268                         return -EINVAL;
 269                 }
 270         case IIO_CHAN_INFO_OFFSET:
 271                 *val = 1093 - 2732500 / ad7298_get_ref_voltage(st);
 272                 return IIO_VAL_INT;
 273         }
 274         return -EINVAL;
 275 }
 276
 277 static const struct iio_info ad7298_info = {
 278         .read_raw = &ad7298_read_raw,
 279         .update_scan_mode = ad7298_update_scan_mode,
 280 };
 281
 282 static void ad7298_reg_disable(void *data)
 283 {
 284         struct regulator *reg = data;
 285
 286         regulator_disable(reg);
 287 }
 288
 289 static int ad7298_probe(struct spi_device *spi)
 290 {
 291         struct ad7298_state *st;
 292         struct iio_dev *indio_dev;
 293         int ret;
 294
 295         indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
 296         if (indio_dev == NULL)
 297                 return -ENOMEM;
 298
 299         st = iio_priv(indio_dev);
 300
 301         st->reg = devm_regulator_get_optional(&spi->dev, "vref");
 302         if (!IS_ERR(st->reg)) {
 303                 st->ext_ref = AD7298_EXTREF;
 304         } else {
 305                 ret = PTR_ERR(st->reg);
 306                 if (ret != -ENODEV)
 307                         return ret;
 308
 309                 st->reg = NULL;
 310         }
 311
 312         if (st->reg) {
 313                 ret = regulator_enable(st->reg);
 314                 if (ret)
 315                         return ret;
 316
 317                 ret = devm_add_action_or_reset(&spi->dev, ad7298_reg_disable,
 318                                                st->reg);
 319                 if (ret)
 320                         return ret;
 321         }
 322
 323         st->spi = spi;
 324
 325         indio_dev->name = spi_get_device_id(spi)->name;
 326         indio_dev->modes = INDIO_DIRECT_MODE;
 327         indio_dev->channels = ad7298_channels;
 328         indio_dev->num_channels = ARRAY_SIZE(ad7298_channels);
 329         indio_dev->info = &ad7298_info;
 330
 331         /* Setup default message */
 332
 333         st->scan_single_xfer[0].tx_buf = &st->tx_buf[0];
 334         st->scan_single_xfer[0].len = 2;
 335         st->scan_single_xfer[0].cs_change = 1;
 336         st->scan_single_xfer[1].tx_buf = &st->tx_buf[1];
 337         st->scan_single_xfer[1].len = 2;
 338         st->scan_single_xfer[1].cs_change = 1;
 339         st->scan_single_xfer[2].rx_buf = &st->rx_buf[0];
 340         st->scan_single_xfer[2].len = 2;
 341
 342         spi_message_init(&st->scan_single_msg);
 343         spi_message_add_tail(&st->scan_single_xfer[0], &st->scan_single_msg);
 344         spi_message_add_tail(&st->scan_single_xfer[1], &st->scan_single_msg);
 345         spi_message_add_tail(&st->scan_single_xfer[2], &st->scan_single_msg);
 346
 347         ret = devm_iio_triggered_buffer_setup(&spi->dev, indio_dev, NULL,
 348                         &ad7298_trigger_handler, NULL);
 349         if (ret)
 350                 return ret;
 351
 352         return devm_iio_device_register(&spi->dev, indio_dev);
 353 }
 354
 355 static const struct spi_device_id ad7298_id[] = {
 356         {"ad7298", 0},
 357         {}
 358 };
 359 MODULE_DEVICE_TABLE(spi, ad7298_id);
 360
 361 static struct spi_driver ad7298_driver = {
 362         .driver = {
 363                 .name   = "ad7298",
 364         },
 365         .probe          = ad7298_probe,
 366         .id_table       = ad7298_id,
 367 };
 368 module_spi_driver(ad7298_driver);
 369
 370 MODULE_AUTHOR("Michael Hennerich <michael.hennerich@analog.com>");
 371 MODULE_DESCRIPTION("Analog Devices AD7298 ADC");
 372 MODULE_LICENSE("GPL v2");