drivers/iio/dac/ti-dac7612.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * DAC7612 Dual, 12-Bit Serial input Digital-to-Analog Converter
   4  *
   5  * Copyright 2019 Qtechnology A/S
   6  * 2019 Ricardo Ribalda <ricardo@ribalda.com>
   7  *
   8  * Licensed under the GPL-2.
   9  */
  10 #include <linux/kernel.h>
  11 #include <linux/module.h>
  12 #include <linux/spi/spi.h>
  13 #include <linux/gpio/consumer.h>
  14 #include <linux/iio/iio.h>
  15
  16 #define DAC7612_RESOLUTION 12
  17 #define DAC7612_ADDRESS 4
  18 #define DAC7612_START 5
  19
  20 struct dac7612 {
  21         struct spi_device *spi;
  22         struct gpio_desc *loaddacs;
  23         uint16_t cache[2];
  24
  25         /*
  26          * DMA (thus cache coherency maintenance) requires the
  27          * transfer buffers to live in their own cache lines.
  28          */
  29         uint8_t data[2] ____cacheline_aligned;
  30 };
  31
  32 static int dac7612_cmd_single(struct dac7612 *priv, int channel, u16 val)
  33 {
  34         int ret;
  35
  36         priv->data[0] = BIT(DAC7612_START) | (channel << DAC7612_ADDRESS);
  37         priv->data[0] |= val >> 8;
  38         priv->data[1] = val & 0xff;
  39
  40         priv->cache[channel] = val;
  41
  42         ret = spi_write(priv->spi, priv->data, sizeof(priv->data));
  43         if (ret)
  44                 return ret;
  45
  46         gpiod_set_value(priv->loaddacs, 1);
  47         gpiod_set_value(priv->loaddacs, 0);
  48
  49         return 0;
  50 }
  51
  52 #define dac7612_CHANNEL(chan, name) {                           \
  53         .type = IIO_VOLTAGE,                                    \
  54         .channel = (chan),                                      \
  55         .indexed = 1,                                           \
  56         .output = 1,                                            \
  57         .datasheet_name = name,                                 \
  58         .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),           \
  59         .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),   \
  60 }
  61
  62 static const struct iio_chan_spec dac7612_channels[] = {
  63         dac7612_CHANNEL(0, "OUTA"),
  64         dac7612_CHANNEL(1, "OUTB"),
  65 };
  66
  67 static int dac7612_read_raw(struct iio_dev *iio_dev,
  68                             const struct iio_chan_spec *chan,
  69                             int *val, int *val2, long mask)
  70 {
  71         struct dac7612 *priv;
  72
  73         switch (mask) {
  74         case IIO_CHAN_INFO_RAW:
  75                 priv = iio_priv(iio_dev);
  76                 *val = priv->cache[chan->channel];
  77                 return IIO_VAL_INT;
  78
  79         case IIO_CHAN_INFO_SCALE:
  80                 *val = 1;
  81                 return IIO_VAL_INT;
  82
  83         default:
  84                 return -EINVAL;
  85         }
  86 }
  87
  88 static int dac7612_write_raw(struct iio_dev *iio_dev,
  89                              const struct iio_chan_spec *chan,
  90                              int val, int val2, long mask)
  91 {
  92         struct dac7612 *priv = iio_priv(iio_dev);
  93         int ret;
  94
  95         if (mask != IIO_CHAN_INFO_RAW)
  96                 return -EINVAL;
  97
  98         if ((val >= BIT(DAC7612_RESOLUTION)) || val < 0 || val2)
  99                 return -EINVAL;
 100
 101         if (val == priv->cache[chan->channel])
 102                 return 0;
 103
 104         mutex_lock(&iio_dev->mlock);
 105         ret = dac7612_cmd_single(priv, chan->channel, val);
 106         mutex_unlock(&iio_dev->mlock);
 107
 108         return ret;
 109 }
 110
 111 static const struct iio_info dac7612_info = {
 112         .read_raw = dac7612_read_raw,
 113         .write_raw = dac7612_write_raw,
 114 };
 115
 116 static int dac7612_probe(struct spi_device *spi)
 117 {
 118         struct iio_dev *iio_dev;
 119         struct dac7612 *priv;
 120         int i;
 121         int ret;
 122
 123         iio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*priv));
 124         if (!iio_dev)
 125                 return -ENOMEM;
 126
 127         priv = iio_priv(iio_dev);
 128         /*
 129          * LOADDACS pin can be controlled by the driver or externally.
 130          * When controlled by the driver, the DAC value is updated after
 131          * every write.
 132          * When the driver does not control the PIN, the user or an external
 133          * event can change the value of all DACs by pulsing down the LOADDACs
 134          * pin.
 135          */
 136         priv->loaddacs = devm_gpiod_get_optional(&spi->dev, "ti,loaddacs",
 137                                                  GPIOD_OUT_LOW);
 138         if (IS_ERR(priv->loaddacs))
 139                 return PTR_ERR(priv->loaddacs);
 140         priv->spi = spi;
 141         spi_set_drvdata(spi, iio_dev);
 142         iio_dev->dev.parent = &spi->dev;
 143         iio_dev->info = &dac7612_info;
 144         iio_dev->modes = INDIO_DIRECT_MODE;
 145         iio_dev->channels = dac7612_channels;
 146         iio_dev->num_channels = ARRAY_SIZE(priv->cache);
 147         iio_dev->name = spi_get_device_id(spi)->name;
 148
 149         for (i = 0; i < ARRAY_SIZE(priv->cache); i++) {
 150                 ret = dac7612_cmd_single(priv, i, 0);
 151                 if (ret)
 152                         return ret;
 153         }
 154
 155         return devm_iio_device_register(&spi->dev, iio_dev);
 156 }
 157
 158 static const struct spi_device_id dac7612_id[] = {
 159         {"ti-dac7612"},
 160         {}
 161 };
 162 MODULE_DEVICE_TABLE(spi, dac7612_id);
 163
 164 static const struct of_device_id dac7612_of_match[] = {
 165         { .compatible = "ti,dac7612" },
 166         { .compatible = "ti,dac7612u" },
 167         { .compatible = "ti,dac7612ub" },
 168         { },
 169 };
 170 MODULE_DEVICE_TABLE(of, dac7612_of_match);
 171
 172 static struct spi_driver dac7612_driver = {
 173         .driver = {
 174                    .name = "ti-dac7612",
 175                    .of_match_table = dac7612_of_match,
 176                    },
 177         .probe = dac7612_probe,
 178         .id_table = dac7612_id,
 179 };
 180 module_spi_driver(dac7612_driver);
 181
 182 MODULE_AUTHOR("Ricardo Ribalda <ricardo@ribalda.com>");
 183 MODULE_DESCRIPTION("Texas Instruments DAC7612 DAC driver");
 184 MODULE_LICENSE("GPL v2");