drivers/staging/iio/adc/ad7780.c

   1 /*
   2  * AD7170/AD7171 and AD7780/AD7781 SPI ADC driver
   3  *
   4  * Copyright 2011 Analog Devices Inc.
   5  *
   6  * Licensed under the GPL-2.
   7  */
   8
   9 #include <linux/interrupt.h>
  10 #include <linux/device.h>
  11 #include <linux/kernel.h>
  12 #include <linux/slab.h>
  13 #include <linux/sysfs.h>
  14 #include <linux/spi/spi.h>
  15 #include <linux/regulator/consumer.h>
  16 #include <linux/err.h>
  17 #include <linux/sched.h>
  18 #include <linux/gpio/consumer.h>
  19 #include <linux/module.h>
  20
  21 #include <linux/iio/iio.h>
  22 #include <linux/iio/sysfs.h>
  23 #include <linux/iio/adc/ad_sigma_delta.h>
  24
  25 #define AD7780_RDY      BIT(7)
  26 #define AD7780_FILTER   BIT(6)
  27 #define AD7780_ERR      BIT(5)
  28 #define AD7780_ID1      BIT(4)
  29 #define AD7780_ID0      BIT(3)
  30 #define AD7780_GAIN     BIT(2)
  31 #define AD7780_PAT1     BIT(1)
  32 #define AD7780_PAT0     BIT(0)
  33
  34 struct ad7780_chip_info {
  35         struct iio_chan_spec    channel;
  36         unsigned int            pattern_mask;
  37         unsigned int            pattern;
  38 };
  39
  40 struct ad7780_state {
  41         const struct ad7780_chip_info   *chip_info;
  42         struct regulator                *reg;
  43         struct gpio_desc                *powerdown_gpio;
  44         unsigned int    gain;
  45         u16                             int_vref_mv;
  46
  47         struct ad_sigma_delta sd;
  48 };
  49
  50 enum ad7780_supported_device_ids {
  51         ID_AD7170,
  52         ID_AD7171,
  53         ID_AD7780,
  54         ID_AD7781,
  55 };
  56
  57 static struct ad7780_state *ad_sigma_delta_to_ad7780(struct ad_sigma_delta *sd)
  58 {
  59         return container_of(sd, struct ad7780_state, sd);
  60 }
  61
  62 static int ad7780_set_mode(struct ad_sigma_delta *sigma_delta,
  63                            enum ad_sigma_delta_mode mode)
  64 {
  65         struct ad7780_state *st = ad_sigma_delta_to_ad7780(sigma_delta);
  66         unsigned val;
  67
  68         switch (mode) {
  69         case AD_SD_MODE_SINGLE:
  70         case AD_SD_MODE_CONTINUOUS:
  71                 val = 1;
  72                 break;
  73         default:
  74                 val = 0;
  75                 break;
  76         }
  77
  78         gpiod_set_value(st->powerdown_gpio, val);
  79
  80         return 0;
  81 }
  82
  83 static int ad7780_read_raw(struct iio_dev *indio_dev,
  84                            struct iio_chan_spec const *chan,
  85                            int *val,
  86                            int *val2,
  87                            long m)
  88 {
  89         struct ad7780_state *st = iio_priv(indio_dev);
  90
  91         switch (m) {
  92         case IIO_CHAN_INFO_RAW:
  93                 return ad_sigma_delta_single_conversion(indio_dev, chan, val);
  94         case IIO_CHAN_INFO_SCALE:
  95                 *val = st->int_vref_mv * st->gain;
  96                 *val2 = chan->scan_type.realbits - 1;
  97                 return IIO_VAL_FRACTIONAL_LOG2;
  98         case IIO_CHAN_INFO_OFFSET:
  99                 *val -= (1 << (chan->scan_type.realbits - 1));
 100                 return IIO_VAL_INT;
 101         }
 102
 103         return -EINVAL;
 104 }
 105
 106 static int ad7780_postprocess_sample(struct ad_sigma_delta *sigma_delta,
 107                                      unsigned int raw_sample)
 108 {
 109         struct ad7780_state *st = ad_sigma_delta_to_ad7780(sigma_delta);
 110         const struct ad7780_chip_info *chip_info = st->chip_info;
 111
 112         if ((raw_sample & AD7780_ERR) ||
 113             ((raw_sample & chip_info->pattern_mask) != chip_info->pattern))
 114                 return -EIO;
 115
 116         if (raw_sample & AD7780_GAIN)
 117                 st->gain = 1;
 118         else
 119                 st->gain = 128;
 120
 121         return 0;
 122 }
 123
 124 static const struct ad_sigma_delta_info ad7780_sigma_delta_info = {
 125         .set_mode = ad7780_set_mode,
 126         .postprocess_sample = ad7780_postprocess_sample,
 127         .has_registers = false,
 128 };
 129
 130 #define AD7780_CHANNEL(bits, wordsize) \
 131         AD_SD_CHANNEL(1, 0, 0, bits, 32, wordsize - bits)
 132
 133 static const struct ad7780_chip_info ad7780_chip_info_tbl[] = {
 134         [ID_AD7170] = {
 135                 .channel = AD7780_CHANNEL(12, 24),
 136                 .pattern = 0x5,
 137                 .pattern_mask = 0x7,
 138         },
 139         [ID_AD7171] = {
 140                 .channel = AD7780_CHANNEL(16, 24),
 141                 .pattern = 0x5,
 142                 .pattern_mask = 0x7,
 143         },
 144         [ID_AD7780] = {
 145                 .channel = AD7780_CHANNEL(24, 32),
 146                 .pattern = 0x1,
 147                 .pattern_mask = 0x3,
 148         },
 149         [ID_AD7781] = {
 150                 .channel = AD7780_CHANNEL(20, 32),
 151                 .pattern = 0x1,
 152                 .pattern_mask = 0x3,
 153         },
 154 };
 155
 156 static const struct iio_info ad7780_info = {
 157         .read_raw = &ad7780_read_raw,
 158         .driver_module = THIS_MODULE,
 159 };
 160
 161 static int ad7780_probe(struct spi_device *spi)
 162 {
 163         struct ad7780_state *st;
 164         struct iio_dev *indio_dev;
 165         int ret, voltage_uv = 0;
 166
 167         indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
 168         if (!indio_dev)
 169                 return -ENOMEM;
 170
 171         st = iio_priv(indio_dev);
 172         st->gain = 1;
 173
 174         ad_sd_init(&st->sd, indio_dev, spi, &ad7780_sigma_delta_info);
 175
 176         st->reg = devm_regulator_get(&spi->dev, "vcc");
 177         if (!IS_ERR(st->reg)) {
 178                 ret = regulator_enable(st->reg);
 179                 if (ret)
 180                         return ret;
 181
 182                 voltage_uv = regulator_get_voltage(st->reg);
 183         }
 184
 185         st->chip_info =
 186                 &ad7780_chip_info_tbl[spi_get_device_id(spi)->driver_data];
 187
 188         if (voltage_uv)
 189                 st->int_vref_mv = voltage_uv / 1000;
 190         else
 191                 dev_warn(&spi->dev, "Reference voltage unspecified\n");
 192
 193         spi_set_drvdata(spi, indio_dev);
 194
 195         indio_dev->dev.parent = &spi->dev;
 196         indio_dev->name = spi_get_device_id(spi)->name;
 197         indio_dev->modes = INDIO_DIRECT_MODE;
 198         indio_dev->channels = &st->chip_info->channel;
 199         indio_dev->num_channels = 1;
 200         indio_dev->info = &ad7780_info;
 201
 202         st->powerdown_gpio = devm_gpiod_get_optional(&spi->dev,
 203                                                      "powerdown",
 204                                                      GPIOD_OUT_LOW);
 205         if (IS_ERR(st->powerdown_gpio)) {
 206                 ret = PTR_ERR(st->powerdown_gpio);
 207                 dev_err(&spi->dev, "Failed to request powerdown GPIO: %d\n",
 208                         ret);
 209                 goto error_disable_reg;
 210         }
 211
 212         ret = ad_sd_setup_buffer_and_trigger(indio_dev);
 213         if (ret)
 214                 goto error_disable_reg;
 215
 216         ret = iio_device_register(indio_dev);
 217         if (ret)
 218                 goto error_cleanup_buffer_and_trigger;
 219
 220         return 0;
 221
 222 error_cleanup_buffer_and_trigger:
 223         ad_sd_cleanup_buffer_and_trigger(indio_dev);
 224 error_disable_reg:
 225         if (!IS_ERR(st->reg))
 226                 regulator_disable(st->reg);
 227
 228         return ret;
 229 }
 230
 231 static int ad7780_remove(struct spi_device *spi)
 232 {
 233         struct iio_dev *indio_dev = spi_get_drvdata(spi);
 234         struct ad7780_state *st = iio_priv(indio_dev);
 235
 236         iio_device_unregister(indio_dev);
 237         ad_sd_cleanup_buffer_and_trigger(indio_dev);
 238
 239         if (!IS_ERR(st->reg))
 240                 regulator_disable(st->reg);
 241
 242         return 0;
 243 }
 244
 245 static const struct spi_device_id ad7780_id[] = {
 246         {"ad7170", ID_AD7170},
 247         {"ad7171", ID_AD7171},
 248         {"ad7780", ID_AD7780},
 249         {"ad7781", ID_AD7781},
 250         {}
 251 };
 252 MODULE_DEVICE_TABLE(spi, ad7780_id);
 253
 254 static struct spi_driver ad7780_driver = {
 255         .driver = {
 256                 .name   = "ad7780",
 257         },
 258         .probe          = ad7780_probe,
 259         .remove         = ad7780_remove,
 260         .id_table       = ad7780_id,
 261 };
 262 module_spi_driver(ad7780_driver);
 263
 264 MODULE_AUTHOR("Michael Hennerich <hennerich@blackfin.uclinux.org>");
 265 MODULE_DESCRIPTION("Analog Devices AD7780 and similar ADCs");
 266 MODULE_LICENSE("GPL v2");