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, indio_dev->masklength);
 113
 114         command = AD7298_WRITE | st->ext_ref;
 115
 116         for (i = 0, m = AD7298_CH(0); i < AD7298_MAX_CHAN; i++, m >>= 1)
 117                 if (test_bit(i, active_scan_mask))
 118                         command |= m;
 119
 120         st->tx_buf[0] = cpu_to_be16(command);
 121
 122         /* build spi ring message */
 123         st->ring_xfer[0].tx_buf = &st->tx_buf[0];
 124         st->ring_xfer[0].len = 2;
 125         st->ring_xfer[0].cs_change = 1;
 126         st->ring_xfer[1].tx_buf = &st->tx_buf[1];
 127         st->ring_xfer[1].len = 2;
 128         st->ring_xfer[1].cs_change = 1;
 129
 130         spi_message_init(&st->ring_msg);
 131         spi_message_add_tail(&st->ring_xfer[0], &st->ring_msg);
 132         spi_message_add_tail(&st->ring_xfer[1], &st->ring_msg);
 133
 134         for (i = 0; i < scan_count; i++) {
 135                 st->ring_xfer[i + 2].rx_buf = &st->rx_buf[i];
 136                 st->ring_xfer[i + 2].len = 2;
 137                 st->ring_xfer[i + 2].cs_change = 1;
 138                 spi_message_add_tail(&st->ring_xfer[i + 2], &st->ring_msg);
 139         }
 140         /* make sure last transfer cs_change is not set */
 141         st->ring_xfer[i + 1].cs_change = 0;
 142
 143         return 0;
 144 }
 145
 146 static irqreturn_t ad7298_trigger_handler(int irq, void *p)
 147 {
 148         struct iio_poll_func *pf = p;
 149         struct iio_dev *indio_dev = pf->indio_dev;
 150         struct ad7298_state *st = iio_priv(indio_dev);
 151         int b_sent;
 152
 153         b_sent = spi_sync(st->spi, &st->ring_msg);
 154         if (b_sent)
 155                 goto done;
 156
 157         iio_push_to_buffers_with_timestamp(indio_dev, st->rx_buf,
 158                 iio_get_time_ns(indio_dev));
 159
 160 done:
 161         iio_trigger_notify_done(indio_dev->trig);
 162
 163         return IRQ_HANDLED;
 164 }
 165
 166 static int ad7298_scan_direct(struct ad7298_state *st, unsigned ch)
 167 {
 168         int ret;
 169         st->tx_buf[0] = cpu_to_be16(AD7298_WRITE | st->ext_ref |
 170                                    (AD7298_CH(0) >> ch));
 171
 172         ret = spi_sync(st->spi, &st->scan_single_msg);
 173         if (ret)
 174                 return ret;
 175
 176         return be16_to_cpu(st->rx_buf[0]);
 177 }
 178
 179 static int ad7298_scan_temp(struct ad7298_state *st, int *val)
 180 {
 181         int ret;
 182         __be16 buf;
 183
 184         buf = cpu_to_be16(AD7298_WRITE | AD7298_TSENSE |
 185                           AD7298_TAVG | st->ext_ref);
 186
 187         ret = spi_write(st->spi, (u8 *)&buf, 2);
 188         if (ret)
 189                 return ret;
 190
 191         buf = cpu_to_be16(0);
 192
 193         ret = spi_write(st->spi, (u8 *)&buf, 2);
 194         if (ret)
 195                 return ret;
 196
 197         usleep_range(101, 1000); /* sleep > 100us */
 198
 199         ret = spi_read(st->spi, (u8 *)&buf, 2);
 200         if (ret)
 201                 return ret;
 202
 203         *val = sign_extend32(be16_to_cpu(buf), 11);
 204
 205         return 0;
 206 }
 207
 208 static int ad7298_get_ref_voltage(struct ad7298_state *st)
 209 {
 210         int vref;
 211
 212         if (st->reg) {
 213                 vref = regulator_get_voltage(st->reg);
 214                 if (vref < 0)
 215                         return vref;
 216
 217                 return vref / 1000;
 218         } else {
 219                 return AD7298_INTREF_mV;
 220         }
 221 }
 222
 223 static int ad7298_read_raw(struct iio_dev *indio_dev,
 224                            struct iio_chan_spec const *chan,
 225                            int *val,
 226                            int *val2,
 227                            long m)
 228 {
 229         int ret;
 230         struct ad7298_state *st = iio_priv(indio_dev);
 231
 232         switch (m) {
 233         case IIO_CHAN_INFO_RAW:
 234                 ret = iio_device_claim_direct_mode(indio_dev);
 235                 if (ret)
 236                         return ret;
 237
 238                 if (chan->address == AD7298_CH_TEMP)
 239                         ret = ad7298_scan_temp(st, val);
 240                 else
 241                         ret = ad7298_scan_direct(st, chan->address);
 242
 243                 iio_device_release_direct_mode(indio_dev);
 244
 245                 if (ret < 0)
 246                         return ret;
 247
 248                 if (chan->address != AD7298_CH_TEMP)
 249                         *val = ret & GENMASK(chan->scan_type.realbits - 1, 0);
 250
 251                 return IIO_VAL_INT;
 252         case IIO_CHAN_INFO_SCALE:
 253                 switch (chan->type) {
 254                 case IIO_VOLTAGE:
 255                         *val = ad7298_get_ref_voltage(st);
 256                         *val2 = chan->scan_type.realbits;
 257                         return IIO_VAL_FRACTIONAL_LOG2;
 258                 case IIO_TEMP:
 259                         *val = ad7298_get_ref_voltage(st);
 260                         *val2 = 10;
 261                         return IIO_VAL_FRACTIONAL;
 262                 default:
 263                         return -EINVAL;
 264                 }
 265         case IIO_CHAN_INFO_OFFSET:
 266                 *val = 1093 - 2732500 / ad7298_get_ref_voltage(st);
 267                 return IIO_VAL_INT;
 268         }
 269         return -EINVAL;
 270 }
 271
 272 static const struct iio_info ad7298_info = {
 273         .read_raw = &ad7298_read_raw,
 274         .update_scan_mode = ad7298_update_scan_mode,
 275 };
 276
 277 static void ad7298_reg_disable(void *data)
 278 {
 279         struct regulator *reg = data;
 280
 281         regulator_disable(reg);
 282 }
 283
 284 static int ad7298_probe(struct spi_device *spi)
 285 {
 286         struct ad7298_state *st;
 287         struct iio_dev *indio_dev;
 288         int ret;
 289
 290         indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
 291         if (indio_dev == NULL)
 292                 return -ENOMEM;
 293
 294         st = iio_priv(indio_dev);
 295
 296         st->reg = devm_regulator_get_optional(&spi->dev, "vref");
 297         if (!IS_ERR(st->reg)) {
 298                 st->ext_ref = AD7298_EXTREF;
 299         } else {
 300                 ret = PTR_ERR(st->reg);
 301                 if (ret != -ENODEV)
 302                         return ret;
 303
 304                 st->reg = NULL;
 305         }
 306
 307         if (st->reg) {
 308                 ret = regulator_enable(st->reg);
 309                 if (ret)
 310                         return ret;
 311
 312                 ret = devm_add_action_or_reset(&spi->dev, ad7298_reg_disable,
 313                                                st->reg);
 314                 if (ret)
 315                         return ret;
 316         }
 317
 318         st->spi = spi;
 319
 320         indio_dev->name = spi_get_device_id(spi)->name;
 321         indio_dev->modes = INDIO_DIRECT_MODE;
 322         indio_dev->channels = ad7298_channels;
 323         indio_dev->num_channels = ARRAY_SIZE(ad7298_channels);
 324         indio_dev->info = &ad7298_info;
 325
 326         /* Setup default message */
 327
 328         st->scan_single_xfer[0].tx_buf = &st->tx_buf[0];
 329         st->scan_single_xfer[0].len = 2;
 330         st->scan_single_xfer[0].cs_change = 1;
 331         st->scan_single_xfer[1].tx_buf = &st->tx_buf[1];
 332         st->scan_single_xfer[1].len = 2;
 333         st->scan_single_xfer[1].cs_change = 1;
 334         st->scan_single_xfer[2].rx_buf = &st->rx_buf[0];
 335         st->scan_single_xfer[2].len = 2;
 336
 337         spi_message_init(&st->scan_single_msg);
 338         spi_message_add_tail(&st->scan_single_xfer[0], &st->scan_single_msg);
 339         spi_message_add_tail(&st->scan_single_xfer[1], &st->scan_single_msg);
 340         spi_message_add_tail(&st->scan_single_xfer[2], &st->scan_single_msg);
 341
 342         ret = devm_iio_triggered_buffer_setup(&spi->dev, indio_dev, NULL,
 343                         &ad7298_trigger_handler, NULL);
 344         if (ret)
 345                 return ret;
 346
 347         return devm_iio_device_register(&spi->dev, indio_dev);
 348 }
 349
 350 static const struct acpi_device_id ad7298_acpi_ids[] = {
 351         { "INT3494", 0 },
 352         { }
 353 };
 354 MODULE_DEVICE_TABLE(acpi, ad7298_acpi_ids);
 355
 356 static const struct spi_device_id ad7298_id[] = {
 357         {"ad7298", 0},
 358         {}
 359 };
 360 MODULE_DEVICE_TABLE(spi, ad7298_id);
 361
 362 static struct spi_driver ad7298_driver = {
 363         .driver = {
 364                 .name   = "ad7298",
 365                 .acpi_match_table = ad7298_acpi_ids,
 366         },
 367         .probe          = ad7298_probe,
 368         .id_table       = ad7298_id,
 369 };
 370 module_spi_driver(ad7298_driver);
 371
 372 MODULE_AUTHOR("Michael Hennerich <michael.hennerich@analog.com>");
 373 MODULE_DESCRIPTION("Analog Devices AD7298 ADC");
 374 MODULE_LICENSE("GPL v2");