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iio: dac: Add support for external reference voltage through the regulator framework. 

Signed-off-by: Silvan Murer <silvan.murer@gmail.com>
Reviewed-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
hifive-unleashed-5.1
Silvan Murer 2018-05-21 14:21:28 +02:00 committed by Jonathan Cameron
parent 0f6a2165af
commit 9ff1d5009f
2 changed files with 75 additions and 9 deletions
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14
Documentation/devicetree/bindings/iio/dac/ltc2632.txt
View File

@ -12,12 +12,26 @@ Required properties:
Property rules described in Documentation/devicetree/bindings/spi/spi-bus.txt
apply. In particular, "reg" and "spi-max-frequency" properties must be given.
Optional properties:
- vref-supply: Phandle to the external reference voltage supply. This should
only be set if there is an external reference voltage connected to the VREF
pin. If the property is not set the internal reference is used.
Example:
vref: regulator-vref {
compatible = "regulator-fixed";
regulator-name = "vref-ltc2632";
regulator-min-microvolt = <1250000>;
regulator-max-microvolt = <1250000>;
regulator-always-on;
};
spi_master {
dac: ltc2632@0 {
compatible = "lltc,ltc2632-l12";
reg = <0>; /* CS0 */
spi-max-frequency = <1000000>;
vref-supply = <&vref>; /* optional */
};
};

70
drivers/iio/dac/ltc2632.c
View File

@ -2,6 +2,7 @@
* LTC2632 Digital to analog convertors spi driver
*
* Copyright 2017 Maxime Roussin-Bélanger
* expanded by Silvan Murer <silvan.murer@gmail.com>
*
* Licensed under the GPL-2.
*/
@ -10,6 +11,7 @@
#include <linux/spi/spi.h>
#include <linux/module.h>
#include <linux/iio/iio.h>
#include <linux/regulator/consumer.h>
#define LTC2632_DAC_CHANNELS 2
@ -28,7 +30,7 @@
/**
* struct ltc2632_chip_info - chip specific information
* @channels: channel spec for the DAC
* @vref_mv: reference voltage
* @vref_mv: internal reference voltage
*/
struct ltc2632_chip_info {
const struct iio_chan_spec *channels;
@ -39,10 +41,14 @@ struct ltc2632_chip_info {
* struct ltc2632_state - driver instance specific data
* @spi_dev: pointer to the spi_device struct
* @powerdown_cache_mask used to show current channel powerdown state
* @vref_mv used reference voltage (internal or external)
* @vref_reg regulator for the reference voltage
*/
struct ltc2632_state {
struct spi_device *spi_dev;
unsigned int powerdown_cache_mask;
int vref_mv;
struct regulator *vref_reg;
};
enum ltc2632_supported_device_ids {
@ -90,7 +96,7 @@ static int ltc2632_read_raw(struct iio_dev *indio_dev,
switch (m) {
case IIO_CHAN_INFO_SCALE:
*val = chip_info->vref_mv;
*val = st->vref_mv;
*val2 = chan->scan_type.realbits;
return IIO_VAL_FRACTIONAL_LOG2;
}
@ -246,6 +252,45 @@ static int ltc2632_probe(struct spi_device *spi)
chip_info = (struct ltc2632_chip_info *)
spi_get_device_id(spi)->driver_data;
st->vref_reg = devm_regulator_get_optional(&spi->dev, "vref");
if (PTR_ERR(st->vref_reg) == -ENODEV) {
/* use internal reference voltage */
st->vref_reg = NULL;
st->vref_mv = chip_info->vref_mv;
ret = ltc2632_spi_write(spi, LTC2632_CMD_INTERNAL_REFER,
0, 0, 0);
if (ret) {
dev_err(&spi->dev,
"Set internal reference command failed, %d\n",
ret);
return ret;
}
} else if (IS_ERR(st->vref_reg)) {
dev_err(&spi->dev,
"Error getting voltage reference regulator\n");
return PTR_ERR(st->vref_reg);
} else {
/* use external reference voltage */
ret = regulator_enable(st->vref_reg);
if (ret) {
dev_err(&spi->dev,
"enable reference regulator failed, %d\n",
ret);
return ret;
}
st->vref_mv = regulator_get_voltage(st->vref_reg) / 1000;
ret = ltc2632_spi_write(spi, LTC2632_CMD_EXTERNAL_REFER,
0, 0, 0);
if (ret) {
dev_err(&spi->dev,
"Set external reference command failed, %d\n",
ret);
return ret;
}
}
indio_dev->dev.parent = &spi->dev;
indio_dev->name = dev_of_node(&spi->dev) ? dev_of_node(&spi->dev)->name
: spi_get_device_id(spi)->name;
@ -254,14 +299,20 @@ static int ltc2632_probe(struct spi_device *spi)
indio_dev->channels = chip_info->channels;
indio_dev->num_channels = LTC2632_DAC_CHANNELS;
ret = ltc2632_spi_write(spi, LTC2632_CMD_INTERNAL_REFER, 0, 0, 0);
if (ret) {
dev_err(&spi->dev,
"Set internal reference command failed, %d\n", ret);
return ret;
}
return iio_device_register(indio_dev);
}
return devm_iio_device_register(&spi->dev, indio_dev);
static int ltc2632_remove(struct spi_device *spi)
{
struct iio_dev *indio_dev = spi_get_drvdata(spi);
struct ltc2632_state *st = iio_priv(indio_dev);
iio_device_unregister(indio_dev);
if (st->vref_reg)
regulator_disable(st->vref_reg);
return 0;
}
static const struct spi_device_id ltc2632_id[] = {
@ -305,6 +356,7 @@ static struct spi_driver ltc2632_driver = {
.of_match_table = of_match_ptr(ltc2632_of_match),
},
.probe = ltc2632_probe,
.remove = ltc2632_remove,
.id_table = ltc2632_id,
};
module_spi_driver(ltc2632_driver);