drivers/iio/amplifiers/ad8366.c

   1 /*
   2  * AD8366 SPI Dual-Digital Variable Gain Amplifier (VGA)
   3  *
   4  * Copyright 2012 Analog Devices Inc.
   5  *
   6  * Licensed under the GPL-2.
   7  */
   8
   9 #include <linux/device.h>
  10 #include <linux/kernel.h>
  11 #include <linux/slab.h>
  12 #include <linux/sysfs.h>
  13 #include <linux/spi/spi.h>
  14 #include <linux/regulator/consumer.h>
  15 #include <linux/err.h>
  16 #include <linux/module.h>
  17 #include <linux/bitrev.h>
  18
  19 #include <linux/iio/iio.h>
  20 #include <linux/iio/sysfs.h>
  21
  22 struct ad8366_state {
  23         struct spi_device       *spi;
  24         struct regulator        *reg;
  25         unsigned char           ch[2];
  26         /*
  27          * DMA (thus cache coherency maintenance) requires the
  28          * transfer buffers to live in their own cache lines.
  29          */
  30         unsigned char           data[2] ____cacheline_aligned;
  31 };
  32
  33 static int ad8366_write(struct iio_dev *indio_dev,
  34                         unsigned char ch_a, unsigned char ch_b)
  35 {
  36         struct ad8366_state *st = iio_priv(indio_dev);
  37         int ret;
  38
  39         ch_a = bitrev8(ch_a & 0x3F);
  40         ch_b = bitrev8(ch_b & 0x3F);
  41
  42         st->data[0] = ch_b >> 4;
  43         st->data[1] = (ch_b << 4) | (ch_a >> 2);
  44
  45         ret = spi_write(st->spi, st->data, ARRAY_SIZE(st->data));
  46         if (ret < 0)
  47                 dev_err(&indio_dev->dev, "write failed (%d)", ret);
  48
  49         return ret;
  50 }
  51
  52 static int ad8366_read_raw(struct iio_dev *indio_dev,
  53                            struct iio_chan_spec const *chan,
  54                            int *val,
  55                            int *val2,
  56                            long m)
  57 {
  58         struct ad8366_state *st = iio_priv(indio_dev);
  59         int ret;
  60         unsigned code;
  61
  62         mutex_lock(&indio_dev->mlock);
  63         switch (m) {
  64         case IIO_CHAN_INFO_HARDWAREGAIN:
  65                 code = st->ch[chan->channel];
  66
  67                 /* Values in dB */
  68                 code = code * 253 + 4500;
  69                 *val = code / 1000;
  70                 *val2 = (code % 1000) * 1000;
  71
  72                 ret = IIO_VAL_INT_PLUS_MICRO_DB;
  73                 break;
  74         default:
  75                 ret = -EINVAL;
  76         }
  77         mutex_unlock(&indio_dev->mlock);
  78
  79         return ret;
  80 };
  81
  82 static int ad8366_write_raw(struct iio_dev *indio_dev,
  83                             struct iio_chan_spec const *chan,
  84                             int val,
  85                             int val2,
  86                             long mask)
  87 {
  88         struct ad8366_state *st = iio_priv(indio_dev);
  89         unsigned code;
  90         int ret;
  91
  92         if (val < 0 || val2 < 0)
  93                 return -EINVAL;
  94
  95         /* Values in dB */
  96         code = (((u8)val * 1000) + ((u32)val2 / 1000));
  97
  98         if (code > 20500 || code < 4500)
  99                 return -EINVAL;
 100
 101         code = (code - 4500) / 253;
 102
 103         mutex_lock(&indio_dev->mlock);
 104         switch (mask) {
 105         case IIO_CHAN_INFO_HARDWAREGAIN:
 106                 st->ch[chan->channel] = code;
 107                 ret = ad8366_write(indio_dev, st->ch[0], st->ch[1]);
 108                 break;
 109         default:
 110                 ret = -EINVAL;
 111         }
 112         mutex_unlock(&indio_dev->mlock);
 113
 114         return ret;
 115 }
 116
 117 static const struct iio_info ad8366_info = {
 118         .read_raw = &ad8366_read_raw,
 119         .write_raw = &ad8366_write_raw,
 120         .driver_module = THIS_MODULE,
 121 };
 122
 123 #define AD8366_CHAN(_channel) {                         \
 124         .type = IIO_VOLTAGE,                            \
 125         .output = 1,                                    \
 126         .indexed = 1,                                   \
 127         .channel = _channel,                            \
 128         .info_mask_separate = BIT(IIO_CHAN_INFO_HARDWAREGAIN),\
 129 }
 130
 131 static const struct iio_chan_spec ad8366_channels[] = {
 132         AD8366_CHAN(0),
 133         AD8366_CHAN(1),
 134 };
 135
 136 static int ad8366_probe(struct spi_device *spi)
 137 {
 138         struct iio_dev *indio_dev;
 139         struct ad8366_state *st;
 140         int ret;
 141
 142         indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
 143         if (indio_dev == NULL)
 144                 return -ENOMEM;
 145
 146         st = iio_priv(indio_dev);
 147
 148         st->reg = devm_regulator_get(&spi->dev, "vcc");
 149         if (!IS_ERR(st->reg)) {
 150                 ret = regulator_enable(st->reg);
 151                 if (ret)
 152                         return ret;
 153         }
 154
 155         spi_set_drvdata(spi, indio_dev);
 156         st->spi = spi;
 157
 158         indio_dev->dev.parent = &spi->dev;
 159         indio_dev->name = spi_get_device_id(spi)->name;
 160         indio_dev->info = &ad8366_info;
 161         indio_dev->modes = INDIO_DIRECT_MODE;
 162         indio_dev->channels = ad8366_channels;
 163         indio_dev->num_channels = ARRAY_SIZE(ad8366_channels);
 164
 165         ret = iio_device_register(indio_dev);
 166         if (ret)
 167                 goto error_disable_reg;
 168
 169         ad8366_write(indio_dev, 0, 0);
 170
 171         return 0;
 172
 173 error_disable_reg:
 174         if (!IS_ERR(st->reg))
 175                 regulator_disable(st->reg);
 176
 177         return ret;
 178 }
 179
 180 static int ad8366_remove(struct spi_device *spi)
 181 {
 182         struct iio_dev *indio_dev = spi_get_drvdata(spi);
 183         struct ad8366_state *st = iio_priv(indio_dev);
 184         struct regulator *reg = st->reg;
 185
 186         iio_device_unregister(indio_dev);
 187
 188         if (!IS_ERR(reg))
 189                 regulator_disable(reg);
 190
 191         return 0;
 192 }
 193
 194 static const struct spi_device_id ad8366_id[] = {
 195         {"ad8366", 0},
 196         {}
 197 };
 198 MODULE_DEVICE_TABLE(spi, ad8366_id);
 199
 200 static struct spi_driver ad8366_driver = {
 201         .driver = {
 202                 .name   = KBUILD_MODNAME,
 203         },
 204         .probe          = ad8366_probe,
 205         .remove         = ad8366_remove,
 206         .id_table       = ad8366_id,
 207 };
 208
 209 module_spi_driver(ad8366_driver);
 210
 211 MODULE_AUTHOR("Michael Hennerich <hennerich@blackfin.uclinux.org>");
 212 MODULE_DESCRIPTION("Analog Devices AD8366 VGA");
 213 MODULE_LICENSE("GPL v2");