drivers/iio/adc/ad7766.c

   1 /*
   2  * AD7766/AD7767 SPI ADC driver
   3  *
   4  * Copyright 2016 Analog Devices Inc.
   5  *
   6  * Licensed under the GPL-2 or later.
   7  */
   8
   9 #include <linux/clk.h>
  10 #include <linux/delay.h>
  11 #include <linux/device.h>
  12 #include <linux/err.h>
  13 #include <linux/gpio/consumer.h>
  14 #include <linux/module.h>
  15 #include <linux/regulator/consumer.h>
  16 #include <linux/slab.h>
  17 #include <linux/spi/spi.h>
  18
  19 #include <linux/iio/iio.h>
  20 #include <linux/iio/buffer.h>
  21 #include <linux/iio/trigger.h>
  22 #include <linux/iio/trigger_consumer.h>
  23 #include <linux/iio/triggered_buffer.h>
  24
  25 struct ad7766_chip_info {
  26         unsigned int decimation_factor;
  27 };
  28
  29 enum {
  30         AD7766_SUPPLY_AVDD = 0,
  31         AD7766_SUPPLY_DVDD = 1,
  32         AD7766_SUPPLY_VREF = 2,
  33         AD7766_NUM_SUPPLIES = 3
  34 };
  35
  36 struct ad7766 {
  37         const struct ad7766_chip_info *chip_info;
  38         struct spi_device *spi;
  39         struct clk *mclk;
  40         struct gpio_desc *pd_gpio;
  41         struct regulator_bulk_data reg[AD7766_NUM_SUPPLIES];
  42
  43         struct iio_trigger *trig;
  44
  45         struct spi_transfer xfer;
  46         struct spi_message msg;
  47
  48         /*
  49          * DMA (thus cache coherency maintenance) requires the
  50          * transfer buffers to live in their own cache lines.
  51          * Make the buffer large enough for one 24 bit sample and one 64 bit
  52          * aligned 64 bit timestamp.
  53          */
  54         unsigned char data[ALIGN(3, sizeof(s64)) + sizeof(s64)]
  55                         ____cacheline_aligned;
  56 };
  57
  58 /*
  59  * AD7766 and AD7767 variations are interface compatible, the main difference is
  60  * analog performance. Both parts will use the same ID.
  61  */
  62 enum ad7766_device_ids {
  63         ID_AD7766,
  64         ID_AD7766_1,
  65         ID_AD7766_2,
  66 };
  67
  68 static irqreturn_t ad7766_trigger_handler(int irq, void *p)
  69 {
  70         struct iio_poll_func *pf = p;
  71         struct iio_dev *indio_dev = pf->indio_dev;
  72         struct ad7766 *ad7766 = iio_priv(indio_dev);
  73         int ret;
  74
  75         ret = spi_sync(ad7766->spi, &ad7766->msg);
  76         if (ret < 0)
  77                 goto done;
  78
  79         iio_push_to_buffers_with_timestamp(indio_dev, ad7766->data,
  80                 pf->timestamp);
  81 done:
  82         iio_trigger_notify_done(indio_dev->trig);
  83
  84         return IRQ_HANDLED;
  85 }
  86
  87 static int ad7766_preenable(struct iio_dev *indio_dev)
  88 {
  89         struct ad7766 *ad7766 = iio_priv(indio_dev);
  90         int ret;
  91
  92         ret = regulator_bulk_enable(ARRAY_SIZE(ad7766->reg), ad7766->reg);
  93         if (ret < 0) {
  94                 dev_err(&ad7766->spi->dev, "Failed to enable supplies: %d\n",
  95                         ret);
  96                 return ret;
  97         }
  98
  99         ret = clk_prepare_enable(ad7766->mclk);
 100         if (ret < 0) {
 101                 dev_err(&ad7766->spi->dev, "Failed to enable MCLK: %d\n", ret);
 102                 regulator_bulk_disable(ARRAY_SIZE(ad7766->reg), ad7766->reg);
 103                 return ret;
 104         }
 105
 106         gpiod_set_value(ad7766->pd_gpio, 0);
 107
 108         return 0;
 109 }
 110
 111 static int ad7766_postdisable(struct iio_dev *indio_dev)
 112 {
 113         struct ad7766 *ad7766 = iio_priv(indio_dev);
 114
 115         gpiod_set_value(ad7766->pd_gpio, 1);
 116
 117         /*
 118          * The PD pin is synchronous to the clock, so give it some time to
 119          * notice the change before we disable the clock.
 120          */
 121         msleep(20);
 122
 123         clk_disable_unprepare(ad7766->mclk);
 124         regulator_bulk_disable(ARRAY_SIZE(ad7766->reg), ad7766->reg);
 125
 126         return 0;
 127 }
 128
 129 static int ad7766_read_raw(struct iio_dev *indio_dev,
 130         const struct iio_chan_spec *chan, int *val, int *val2, long info)
 131 {
 132         struct ad7766 *ad7766 = iio_priv(indio_dev);
 133         struct regulator *vref = ad7766->reg[AD7766_SUPPLY_VREF].consumer;
 134         int scale_uv;
 135
 136         switch (info) {
 137         case IIO_CHAN_INFO_SCALE:
 138                 scale_uv = regulator_get_voltage(vref);
 139                 if (scale_uv < 0)
 140                         return scale_uv;
 141                 *val = scale_uv / 1000;
 142                 *val2 = chan->scan_type.realbits;
 143                 return IIO_VAL_FRACTIONAL_LOG2;
 144         case IIO_CHAN_INFO_SAMP_FREQ:
 145                 *val = clk_get_rate(ad7766->mclk) /
 146                         ad7766->chip_info->decimation_factor;
 147                 return IIO_VAL_INT;
 148         }
 149         return -EINVAL;
 150 }
 151
 152 static const struct iio_chan_spec ad7766_channels[] = {
 153         {
 154                 .type = IIO_VOLTAGE,
 155                 .indexed = 1,
 156                 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),
 157                 .info_mask_shared_by_all = BIT(IIO_CHAN_INFO_SAMP_FREQ),
 158                 .scan_type = {
 159                         .sign = 's',
 160                         .realbits = 24,
 161                         .storagebits = 32,
 162                         .endianness = IIO_BE,
 163                 },
 164         },
 165         IIO_CHAN_SOFT_TIMESTAMP(1),
 166 };
 167
 168 static const struct ad7766_chip_info ad7766_chip_info[] = {
 169         [ID_AD7766] = {
 170                 .decimation_factor = 8,
 171         },
 172         [ID_AD7766_1] = {
 173                 .decimation_factor = 16,
 174         },
 175         [ID_AD7766_2] = {
 176                 .decimation_factor = 32,
 177         },
 178 };
 179
 180 static const struct iio_buffer_setup_ops ad7766_buffer_setup_ops = {
 181         .preenable = &ad7766_preenable,
 182         .postenable = &iio_triggered_buffer_postenable,
 183         .predisable = &iio_triggered_buffer_predisable,
 184         .postdisable = &ad7766_postdisable,
 185 };
 186
 187 static const struct iio_info ad7766_info = {
 188         .read_raw = &ad7766_read_raw,
 189 };
 190
 191 static irqreturn_t ad7766_irq(int irq, void *private)
 192 {
 193         iio_trigger_poll(private);
 194         return IRQ_HANDLED;
 195 }
 196
 197 static int ad7766_set_trigger_state(struct iio_trigger *trig, bool enable)
 198 {
 199         struct ad7766 *ad7766 = iio_trigger_get_drvdata(trig);
 200
 201         if (enable)
 202                 enable_irq(ad7766->spi->irq);
 203         else
 204                 disable_irq(ad7766->spi->irq);
 205
 206         return 0;
 207 }
 208
 209 static const struct iio_trigger_ops ad7766_trigger_ops = {
 210         .set_trigger_state = ad7766_set_trigger_state,
 211         .validate_device = iio_trigger_validate_own_device,
 212 };
 213
 214 static int ad7766_probe(struct spi_device *spi)
 215 {
 216         const struct spi_device_id *id = spi_get_device_id(spi);
 217         struct iio_dev *indio_dev;
 218         struct ad7766 *ad7766;
 219         int ret;
 220
 221         indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*ad7766));
 222         if (!indio_dev)
 223                 return -ENOMEM;
 224
 225         ad7766 = iio_priv(indio_dev);
 226         ad7766->chip_info = &ad7766_chip_info[id->driver_data];
 227
 228         ad7766->mclk = devm_clk_get(&spi->dev, "mclk");
 229         if (IS_ERR(ad7766->mclk))
 230                 return PTR_ERR(ad7766->mclk);
 231
 232         ad7766->reg[AD7766_SUPPLY_AVDD].supply = "avdd";
 233         ad7766->reg[AD7766_SUPPLY_DVDD].supply = "dvdd";
 234         ad7766->reg[AD7766_SUPPLY_VREF].supply = "vref";
 235
 236         ret = devm_regulator_bulk_get(&spi->dev, ARRAY_SIZE(ad7766->reg),
 237                 ad7766->reg);
 238         if (ret)
 239                 return ret;
 240
 241         ad7766->pd_gpio = devm_gpiod_get_optional(&spi->dev, "powerdown",
 242                 GPIOD_OUT_HIGH);
 243         if (IS_ERR(ad7766->pd_gpio))
 244                 return PTR_ERR(ad7766->pd_gpio);
 245
 246         indio_dev->dev.parent = &spi->dev;
 247         indio_dev->name = spi_get_device_id(spi)->name;
 248         indio_dev->modes = INDIO_DIRECT_MODE;
 249         indio_dev->channels = ad7766_channels;
 250         indio_dev->num_channels = ARRAY_SIZE(ad7766_channels);
 251         indio_dev->info = &ad7766_info;
 252
 253         if (spi->irq > 0) {
 254                 ad7766->trig = devm_iio_trigger_alloc(&spi->dev, "%s-dev%d",
 255                         indio_dev->name, indio_dev->id);
 256                 if (!ad7766->trig)
 257                         return -ENOMEM;
 258
 259                 ad7766->trig->ops = &ad7766_trigger_ops;
 260                 ad7766->trig->dev.parent = &spi->dev;
 261                 iio_trigger_set_drvdata(ad7766->trig, ad7766);
 262
 263                 ret = devm_request_irq(&spi->dev, spi->irq, ad7766_irq,
 264                         IRQF_TRIGGER_FALLING, dev_name(&spi->dev),
 265                         ad7766->trig);
 266                 if (ret < 0)
 267                         return ret;
 268
 269                 /*
 270                  * The device generates interrupts as long as it is powered up.
 271                  * Some platforms might not allow the option to power it down so
 272                  * disable the interrupt to avoid extra load on the system
 273                  */
 274                 disable_irq(spi->irq);
 275
 276                 ret = devm_iio_trigger_register(&spi->dev, ad7766->trig);
 277                 if (ret)
 278                         return ret;
 279         }
 280
 281         spi_set_drvdata(spi, indio_dev);
 282
 283         ad7766->spi = spi;
 284
 285         /* First byte always 0 */
 286         ad7766->xfer.rx_buf = &ad7766->data[1];
 287         ad7766->xfer.len = 3;
 288
 289         spi_message_init(&ad7766->msg);
 290         spi_message_add_tail(&ad7766->xfer, &ad7766->msg);
 291
 292         ret = devm_iio_triggered_buffer_setup(&spi->dev, indio_dev,
 293                 &iio_pollfunc_store_time, &ad7766_trigger_handler,
 294                 &ad7766_buffer_setup_ops);
 295         if (ret)
 296                 return ret;
 297
 298         ret = devm_iio_device_register(&spi->dev, indio_dev);
 299         if (ret)
 300                 return ret;
 301         return 0;
 302 }
 303
 304 static const struct spi_device_id ad7766_id[] = {
 305         {"ad7766", ID_AD7766},
 306         {"ad7766-1", ID_AD7766_1},
 307         {"ad7766-2", ID_AD7766_2},
 308         {"ad7767", ID_AD7766},
 309         {"ad7767-1", ID_AD7766_1},
 310         {"ad7767-2", ID_AD7766_2},
 311         {}
 312 };
 313 MODULE_DEVICE_TABLE(spi, ad7766_id);
 314
 315 static struct spi_driver ad7766_driver = {
 316         .driver = {
 317                 .name   = "ad7766",
 318         },
 319         .probe          = ad7766_probe,
 320         .id_table       = ad7766_id,
 321 };
 322 module_spi_driver(ad7766_driver);
 323
 324 MODULE_AUTHOR("Lars-Peter Clausen <lars@metafoo.de>");
 325 MODULE_DESCRIPTION("Analog Devices AD7766 and AD7767 ADCs driver support");
 326 MODULE_LICENSE("GPL v2");