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// SPDX-License-Identifier: GPL-2.0
/*
* DAC7612 Dual, 12-Bit Serial input Digital-to-Analog Converter
*
* Copyright 2019 Qtechnology A/S
* 2019 Ricardo Ribalda <ribalda@kernel.org>
*
* Licensed under the GPL-2.
*/
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/spi/spi.h>
#include <linux/gpio/consumer.h>
#include <linux/iio/iio.h>
#define DAC7612_RESOLUTION 12
#define DAC7612_ADDRESS 4
#define DAC7612_START 5
struct dac7612 {
struct spi_device *spi;
struct gpio_desc *loaddacs;
uint16_t cache[2];
/*
* Lock to protect the state of the device from potential concurrent
* write accesses from userspace. The write operation requires an
* SPI write, then toggling of a GPIO, so the lock aims to protect
* the sanity of the entire sequence of operation.
*/
struct mutex lock;
/*
* DMA (thus cache coherency maintenance) may require the
* transfer buffers to live in their own cache lines.
*/
uint8_t data[2] __aligned(IIO_DMA_MINALIGN);
};
static int dac7612_cmd_single(struct dac7612 *priv, int channel, u16 val)
{
int ret;
priv->data[0] = BIT(DAC7612_START) | (channel << DAC7612_ADDRESS);
priv->data[0] |= val >> 8;
priv->data[1] = val & 0xff;
priv->cache[channel] = val;
ret = spi_write(priv->spi, priv->data, sizeof(priv->data));
if (ret)
return ret;
gpiod_set_value(priv->loaddacs, 1);
gpiod_set_value(priv->loaddacs, 0);
return 0;
}
#define dac7612_CHANNEL(chan, name) { \
.type = IIO_VOLTAGE, \
.channel = (chan), \
.indexed = 1, \
.output = 1, \
.datasheet_name = name, \
.info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
}
static const struct iio_chan_spec dac7612_channels[] = {
dac7612_CHANNEL(0, "OUTA"),
dac7612_CHANNEL(1, "OUTB"),
};
static int dac7612_read_raw(struct iio_dev *iio_dev,
const struct iio_chan_spec *chan,
int *val, int *val2, long mask)
{
struct dac7612 *priv;
switch (mask) {
case IIO_CHAN_INFO_RAW:
priv = iio_priv(iio_dev);
*val = priv->cache[chan->channel];
return IIO_VAL_INT;
case IIO_CHAN_INFO_SCALE:
*val = 1;
return IIO_VAL_INT;
default:
return -EINVAL;
}
}
static int dac7612_write_raw(struct iio_dev *iio_dev,
const struct iio_chan_spec *chan,
int val, int val2, long mask)
{
struct dac7612 *priv = iio_priv(iio_dev);
int ret;
if (mask != IIO_CHAN_INFO_RAW)
return -EINVAL;
if ((val >= BIT(DAC7612_RESOLUTION)) || val < 0 || val2)
return -EINVAL;
if (val == priv->cache[chan->channel])
return 0;
mutex_lock(&priv->lock);
ret = dac7612_cmd_single(priv, chan->channel, val);
mutex_unlock(&priv->lock);
return ret;
}
static const struct iio_info dac7612_info = {
.read_raw = dac7612_read_raw,
.write_raw = dac7612_write_raw,
};
static int dac7612_probe(struct spi_device *spi)
{
struct iio_dev *iio_dev;
struct dac7612 *priv;
int i;
int ret;
iio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*priv));
if (!iio_dev)
return -ENOMEM;
priv = iio_priv(iio_dev);
/*
* LOADDACS pin can be controlled by the driver or externally.
* When controlled by the driver, the DAC value is updated after
* every write.
* When the driver does not control the PIN, the user or an external
* event can change the value of all DACs by pulsing down the LOADDACs
* pin.
*/
priv->loaddacs = devm_gpiod_get_optional(&spi->dev, "ti,loaddacs",
GPIOD_OUT_LOW);
if (IS_ERR(priv->loaddacs))
return PTR_ERR(priv->loaddacs);
priv->spi = spi;
spi_set_drvdata(spi, iio_dev);
iio_dev->info = &dac7612_info;
iio_dev->modes = INDIO_DIRECT_MODE;
iio_dev->channels = dac7612_channels;
iio_dev->num_channels = ARRAY_SIZE(priv->cache);
iio_dev->name = spi_get_device_id(spi)->name;
mutex_init(&priv->lock);
for (i = 0; i < ARRAY_SIZE(priv->cache); i++) {
ret = dac7612_cmd_single(priv, i, 0);
if (ret)
return ret;
}
return devm_iio_device_register(&spi->dev, iio_dev);
}
static const struct spi_device_id dac7612_id[] = {
{"ti-dac7612"},
{}
};
MODULE_DEVICE_TABLE(spi, dac7612_id);
static const struct of_device_id dac7612_of_match[] = {
{ .compatible = "ti,dac7612" },
{ .compatible = "ti,dac7612u" },
{ .compatible = "ti,dac7612ub" },
{ },
};
MODULE_DEVICE_TABLE(of, dac7612_of_match);
static struct spi_driver dac7612_driver = {
.driver = {
.name = "ti-dac7612",
.of_match_table = dac7612_of_match,
},
.probe = dac7612_probe,
.id_table = dac7612_id,
};
module_spi_driver(dac7612_driver);
MODULE_AUTHOR("Ricardo Ribalda <ribalda@kernel.org>");
MODULE_DESCRIPTION("Texas Instruments DAC7612 DAC driver");
MODULE_LICENSE("GPL v2");
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