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/mod_devicetable.h>
  17 #include <linux/module.h>
  18 #include <linux/interrupt.h>
  19 #include <linux/bitops.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 AD7298_WRITE    BIT(15) /* write to the control register */
  28 #define AD7298_REPEAT   BIT(14) /* repeated conversion enable */
  29 #define AD7298_CH(x)    BIT(13 - (x)) /* channel select */
  30 #define AD7298_TSENSE   BIT(5) /* temperature conversion enable */
  31 #define AD7298_EXTREF   BIT(2) /* external reference enable */
  32 #define AD7298_TAVG     BIT(1) /* temperature sensor averaging enable */
  33 #define AD7298_PDD      BIT(0) /* partial power down enable */
  34
  35 #define AD7298_MAX_CHAN         8
  36 #define AD7298_INTREF_mV        2500
  37
  38 #define AD7298_CH_TEMP          9
  39
  40 struct ad7298_state {
  41         struct spi_device               *spi;
  42         struct regulator                *reg;
  43         unsigned                        ext_ref;
  44         struct spi_transfer             ring_xfer[10];
  45         struct spi_transfer             scan_single_xfer[3];
  46         struct spi_message              ring_msg;
  47         struct spi_message              scan_single_msg;
  48         /*
  49          * DMA (thus cache coherency maintenance) requires the
  50          * transfer buffers to live in their own cache lines.
  51          */
  52         __be16                          rx_buf[12] __aligned(IIO_DMA_MINALIGN);
  53         __be16                          tx_buf[2];
  54 };
  55
  56 #define AD7298_V_CHAN(index)                                            \
  57         {                                                               \
  58                 .type = IIO_VOLTAGE,                                    \
  59                 .indexed = 1,                                           \
  60                 .channel = index,                                       \
  61                 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),           \
  62                 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),   \
  63                 .address = index,                                       \
  64                 .scan_index = index,                                    \
  65                 .scan_type = {                                          \
  66                         .sign = 'u',                                    \
  67                         .realbits = 12,                                 \
  68                         .storagebits = 16,                              \
  69                         .endianness = IIO_BE,                           \
  70                 },                                                      \
  71         }
  72
  73 static const struct iio_chan_spec ad7298_channels[] = {
  74         {
  75                 .type = IIO_TEMP,
  76                 .indexed = 1,
  77                 .channel = 0,
  78                 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
  79                         BIT(IIO_CHAN_INFO_SCALE) |
  80                         BIT(IIO_CHAN_INFO_OFFSET),
  81                 .address = AD7298_CH_TEMP,
  82                 .scan_index = -1,
  83                 .scan_type = {
  84                         .sign = 's',
  85                         .realbits = 32,
  86                         .storagebits = 32,
  87                 },
  88         },
  89         AD7298_V_CHAN(0),
  90         AD7298_V_CHAN(1),
  91         AD7298_V_CHAN(2),
  92         AD7298_V_CHAN(3),
  93         AD7298_V_CHAN(4),
  94         AD7298_V_CHAN(5),
  95         AD7298_V_CHAN(6),
  96         AD7298_V_CHAN(7),
  97         IIO_CHAN_SOFT_TIMESTAMP(8),
  98 };
  99
 100 /*
 101  * ad7298_update_scan_mode() setup the spi transfer buffer for the new scan mask
 102  */
 103 static int ad7298_update_scan_mode(struct iio_dev *indio_dev,
 104         const unsigned long *active_scan_mask)
 105 {
 106         struct ad7298_state *st = iio_priv(indio_dev);
 107         int i, m;
 108         unsigned short command;
 109         int scan_count;
 110
 111         /* Now compute overall size */
 112         scan_count = bitmap_weight(active_scan_mask,
 113                                    iio_get_masklength(indio_dev));
 114
 115         command = AD7298_WRITE | st->ext_ref;
 116
 117         for (i = 0, m = AD7298_CH(0); i < AD7298_MAX_CHAN; i++, m >>= 1)
 118                 if (test_bit(i, active_scan_mask))
 119                         command |= m;
 120
 121         st->tx_buf[0] = cpu_to_be16(command);
 122
 123         /* build spi ring message */
 124         st->ring_xfer[0].tx_buf = &st->tx_buf[0];
 125         st->ring_xfer[0].len = 2;
 126         st->ring_xfer[0].cs_change = 1;
 127         st->ring_xfer[1].tx_buf = &st->tx_buf[1];
 128         st->ring_xfer[1].len = 2;
 129         st->ring_xfer[1].cs_change = 1;
 130
 131         spi_message_init(&st->ring_msg);
 132         spi_message_add_tail(&st->ring_xfer[0], &st->ring_msg);
 133         spi_message_add_tail(&st->ring_xfer[1], &st->ring_msg);
 134
 135         for (i = 0; i < scan_count; i++) {
 136                 st->ring_xfer[i + 2].rx_buf = &st->rx_buf[i];
 137                 st->ring_xfer[i + 2].len = 2;
 138                 st->ring_xfer[i + 2].cs_change = 1;
 139                 spi_message_add_tail(&st->ring_xfer[i + 2], &st->ring_msg);
 140         }
 141         /* make sure last transfer cs_change is not set */
 142         st->ring_xfer[i + 1].cs_change = 0;
 143
 144         return 0;
 145 }
 146
 147 static irqreturn_t ad7298_trigger_handler(int irq, void *p)
 148 {
 149         struct iio_poll_func *pf = p;
 150         struct iio_dev *indio_dev = pf->indio_dev;
 151         struct ad7298_state *st = iio_priv(indio_dev);
 152         int b_sent;
 153
 154         b_sent = spi_sync(st->spi, &st->ring_msg);
 155         if (b_sent)
 156                 goto done;
 157
 158         iio_push_to_buffers_with_timestamp(indio_dev, st->rx_buf,
 159                 iio_get_time_ns(indio_dev));
 160
 161 done:
 162         iio_trigger_notify_done(indio_dev->trig);
 163
 164         return IRQ_HANDLED;
 165 }
 166
 167 static int ad7298_scan_direct(struct ad7298_state *st, unsigned ch)
 168 {
 169         int ret;
 170         st->tx_buf[0] = cpu_to_be16(AD7298_WRITE | st->ext_ref |
 171                                    (AD7298_CH(0) >> ch));
 172
 173         ret = spi_sync(st->spi, &st->scan_single_msg);
 174         if (ret)
 175                 return ret;
 176
 177         return be16_to_cpu(st->rx_buf[0]);
 178 }
 179
 180 static int ad7298_scan_temp(struct ad7298_state *st, int *val)
 181 {
 182         int ret;
 183         __be16 buf;
 184
 185         buf = cpu_to_be16(AD7298_WRITE | AD7298_TSENSE |
 186                           AD7298_TAVG | st->ext_ref);
 187
 188         ret = spi_write(st->spi, (u8 *)&buf, 2);
 189         if (ret)
 190                 return ret;
 191
 192         buf = cpu_to_be16(0);
 193
 194         ret = spi_write(st->spi, (u8 *)&buf, 2);
 195         if (ret)
 196                 return ret;
 197
 198         usleep_range(101, 1000); /* sleep > 100us */
 199
 200         ret = spi_read(st->spi, (u8 *)&buf, 2);
 201         if (ret)
 202                 return ret;
 203
 204         *val = sign_extend32(be16_to_cpu(buf), 11);
 205
 206         return 0;
 207 }
 208
 209 static int ad7298_get_ref_voltage(struct ad7298_state *st)
 210 {
 211         int vref;
 212
 213         if (st->reg) {
 214                 vref = regulator_get_voltage(st->reg);
 215                 if (vref < 0)
 216                         return vref;
 217
 218                 return vref / 1000;
 219         } else {
 220                 return AD7298_INTREF_mV;
 221         }
 222 }
 223
 224 static int ad7298_read_raw(struct iio_dev *indio_dev,
 225                            struct iio_chan_spec const *chan,
 226                            int *val,
 227                            int *val2,
 228                            long m)
 229 {
 230         int ret;
 231         struct ad7298_state *st = iio_priv(indio_dev);
 232
 233         switch (m) {
 234         case IIO_CHAN_INFO_RAW:
 235                 ret = iio_device_claim_direct_mode(indio_dev);
 236                 if (ret)
 237                         return ret;
 238
 239                 if (chan->address == AD7298_CH_TEMP)
 240                         ret = ad7298_scan_temp(st, val);
 241                 else
 242                         ret = ad7298_scan_direct(st, chan->address);
 243
 244                 iio_device_release_direct_mode(indio_dev);
 245
 246                 if (ret < 0)
 247                         return ret;
 248
 249                 if (chan->address != AD7298_CH_TEMP)
 250                         *val = ret & GENMASK(chan->scan_type.realbits - 1, 0);
 251
 252                 return IIO_VAL_INT;
 253         case IIO_CHAN_INFO_SCALE:
 254                 switch (chan->type) {
 255                 case IIO_VOLTAGE:
 256                         *val = ad7298_get_ref_voltage(st);
 257                         *val2 = chan->scan_type.realbits;
 258                         return IIO_VAL_FRACTIONAL_LOG2;
 259                 case IIO_TEMP:
 260                         *val = ad7298_get_ref_voltage(st);
 261                         *val2 = 10;
 262                         return IIO_VAL_FRACTIONAL;
 263                 default:
 264                         return -EINVAL;
 265                 }
 266         case IIO_CHAN_INFO_OFFSET:
 267                 *val = 1093 - 2732500 / ad7298_get_ref_voltage(st);
 268                 return IIO_VAL_INT;
 269         }
 270         return -EINVAL;
 271 }
 272
 273 static const struct iio_info ad7298_info = {
 274         .read_raw = &ad7298_read_raw,
 275         .update_scan_mode = ad7298_update_scan_mode,
 276 };
 277
 278 static void ad7298_reg_disable(void *data)
 279 {
 280         struct regulator *reg = data;
 281
 282         regulator_disable(reg);
 283 }
 284
 285 static int ad7298_probe(struct spi_device *spi)
 286 {
 287         struct ad7298_state *st;
 288         struct iio_dev *indio_dev;
 289         int ret;
 290
 291         indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
 292         if (indio_dev == NULL)
 293                 return -ENOMEM;
 294
 295         st = iio_priv(indio_dev);
 296
 297         st->reg = devm_regulator_get_optional(&spi->dev, "vref");
 298         if (!IS_ERR(st->reg)) {
 299                 st->ext_ref = AD7298_EXTREF;
 300         } else {
 301                 ret = PTR_ERR(st->reg);
 302                 if (ret != -ENODEV)
 303                         return ret;
 304
 305                 st->reg = NULL;
 306         }
 307
 308         if (st->reg) {
 309                 ret = regulator_enable(st->reg);
 310                 if (ret)
 311                         return ret;
 312
 313                 ret = devm_add_action_or_reset(&spi->dev, ad7298_reg_disable,
 314                                                st->reg);
 315                 if (ret)
 316                         return ret;
 317         }
 318
 319         st->spi = spi;
 320
 321         indio_dev->name = spi_get_device_id(spi)->name;
 322         indio_dev->modes = INDIO_DIRECT_MODE;
 323         indio_dev->channels = ad7298_channels;
 324         indio_dev->num_channels = ARRAY_SIZE(ad7298_channels);
 325         indio_dev->info = &ad7298_info;
 326
 327         /* Setup default message */
 328
 329         st->scan_single_xfer[0].tx_buf = &st->tx_buf[0];
 330         st->scan_single_xfer[0].len = 2;
 331         st->scan_single_xfer[0].cs_change = 1;
 332         st->scan_single_xfer[1].tx_buf = &st->tx_buf[1];
 333         st->scan_single_xfer[1].len = 2;
 334         st->scan_single_xfer[1].cs_change = 1;
 335         st->scan_single_xfer[2].rx_buf = &st->rx_buf[0];
 336         st->scan_single_xfer[2].len = 2;
 337
 338         spi_message_init(&st->scan_single_msg);
 339         spi_message_add_tail(&st->scan_single_xfer[0], &st->scan_single_msg);
 340         spi_message_add_tail(&st->scan_single_xfer[1], &st->scan_single_msg);
 341         spi_message_add_tail(&st->scan_single_xfer[2], &st->scan_single_msg);
 342
 343         ret = devm_iio_triggered_buffer_setup(&spi->dev, indio_dev, NULL,
 344                         &ad7298_trigger_handler, NULL);
 345         if (ret)
 346                 return ret;
 347
 348         return devm_iio_device_register(&spi->dev, indio_dev);
 349 }
 350
 351 static const struct acpi_device_id ad7298_acpi_ids[] = {
 352         { "INT3494", 0 },
 353         { }
 354 };
 355 MODULE_DEVICE_TABLE(acpi, ad7298_acpi_ids);
 356
 357 static const struct spi_device_id ad7298_id[] = {
 358         { "ad7298", 0 },
 359         { }
 360 };
 361 MODULE_DEVICE_TABLE(spi, ad7298_id);
 362
 363 static struct spi_driver ad7298_driver = {
 364         .driver = {
 365                 .name   = "ad7298",
 366                 .acpi_match_table = ad7298_acpi_ids,
 367         },
 368         .probe          = ad7298_probe,
 369         .id_table       = ad7298_id,
 370 };
 371 module_spi_driver(ad7298_driver);
 372
 373 MODULE_AUTHOR("Michael Hennerich <michael.hennerich@analog.com>");
 374 MODULE_DESCRIPTION("Analog Devices AD7298 ADC");
 375 MODULE_LICENSE("GPL v2");