Re: [PATCH v2 1/3] iio: dac: add support for ltc1660

[Jonathan Cameron <jic23@kernel.org>]

On Tue, 21 Aug 2018 21:31:24 +0200
Marcus Folkesson <marcus.folkesson@gmail.com> wrote:

> LTC1665/LTC1660 is a 8/10-bit Digital-to-Analog Converter
> (DAC) with eight individual channels.
> 
> Signed-off-by: Marcus Folkesson <marcus.folkesson@gmail.com>
Great.

Applied to the togreg branch of iio.git and pushed out as testing
for the autobuilders to play with it.

Thanks,

Jonathan

> ---
> 
> Notes:
>     v2:
>     	- rename all instances of ltc166x to ltc1660
>     	- read regulator value "in-place" instead of cache voltage
>     	- fix error handling in ltc1660_write_raw
> 
>  drivers/iio/dac/Kconfig   |  10 ++
>  drivers/iio/dac/Makefile  |   1 +
>  drivers/iio/dac/ltc1660.c | 250 ++++++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 261 insertions(+)
>  create mode 100644 drivers/iio/dac/ltc1660.c
> 
> diff --git a/drivers/iio/dac/Kconfig b/drivers/iio/dac/Kconfig
> index 76db0768e454..cbee80bd111e 100644
> --- a/drivers/iio/dac/Kconfig
> +++ b/drivers/iio/dac/Kconfig
> @@ -120,6 +120,16 @@ config AD5624R_SPI
>  	  Say yes here to build support for Analog Devices AD5624R, AD5644R and
>  	  AD5664R converters (DAC). This driver uses the common SPI interface.
>  
> +config LTC1660
> +	tristate "Linear Technology LTC1660/LTC1665 DAC SPI driver"
> +	depends on SPI
> +	help
> +	  Say yes here to build support for Linear Technology
> +	  LTC1660 and LTC1665 Digital to Analog Converters.
> +
> +	  To compile this driver as a module, choose M here: the
> +	  module will be called ltc1660.
> +
>  config LTC2632
>  	tristate "Linear Technology LTC2632-12/10/8 DAC spi driver"
>  	depends on SPI
> diff --git a/drivers/iio/dac/Makefile b/drivers/iio/dac/Makefile
> index 81e710ed7491..e446eeb09c85 100644
> --- a/drivers/iio/dac/Makefile
> +++ b/drivers/iio/dac/Makefile
> @@ -26,6 +26,7 @@ obj-$(CONFIG_CIO_DAC) += cio-dac.o
>  obj-$(CONFIG_DPOT_DAC) += dpot-dac.o
>  obj-$(CONFIG_DS4424) += ds4424.o
>  obj-$(CONFIG_LPC18XX_DAC) += lpc18xx_dac.o
> +obj-$(CONFIG_LTC1660) += ltc1660.o
>  obj-$(CONFIG_LTC2632) += ltc2632.o
>  obj-$(CONFIG_M62332) += m62332.o
>  obj-$(CONFIG_MAX517) += max517.o
> diff --git a/drivers/iio/dac/ltc1660.c b/drivers/iio/dac/ltc1660.c
> new file mode 100644
> index 000000000000..10866838c72a
> --- /dev/null
> +++ b/drivers/iio/dac/ltc1660.c
> @@ -0,0 +1,250 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Driver for Linear Technology LTC1665/LTC1660, 8 channels DAC
> + *
> + * Copyright (C) 2018 Marcus Folkesson <marcus.folkesson@gmail.com>
> + */
> +#include <linux/bitops.h>
> +#include <linux/iio/iio.h>
> +#include <linux/iio/sysfs.h>
> +#include <linux/init.h>
> +#include <linux/module.h>
> +#include <linux/regulator/consumer.h>
> +#include <linux/regmap.h>
> +#include <linux/spi/spi.h>
> +
> +#define LTC1660_REG_WAKE	0x0
> +#define LTC1660_REG_DAC_A	0x1
> +#define LTC1660_REG_DAC_B	0x2
> +#define LTC1660_REG_DAC_C	0x3
> +#define LTC1660_REG_DAC_D	0x4
> +#define LTC1660_REG_DAC_E	0x5
> +#define LTC1660_REG_DAC_F	0x6
> +#define LTC1660_REG_DAC_G	0x7
> +#define LTC1660_REG_DAC_H	0x8
> +#define LTC1660_REG_SLEEP	0xe
> +
> +#define LTC1660_NUM_CHANNELS	8
> +
> +static const struct regmap_config ltc1660_regmap_config = {
> +	.reg_bits = 4,
> +	.val_bits = 12,
> +};
> +
> +enum ltc1660_supported_device_ids {
> +	ID_LTC1660,
> +	ID_LTC1665,
> +};
> +
> +struct ltc1660_priv {
> +	struct spi_device *spi;
> +	struct regmap *regmap;
> +	struct regulator *vref_reg;
> +	unsigned int value[LTC1660_NUM_CHANNELS];
> +	unsigned int vref_mv;
> +};
> +
> +static int ltc1660_read_raw(struct iio_dev *indio_dev,
> +		struct iio_chan_spec const *chan,
> +		int *val,
> +		int *val2,
> +		long mask)
> +{
> +	struct ltc1660_priv *priv = iio_priv(indio_dev);
> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_RAW:
> +		*val = priv->value[chan->channel];
> +		return IIO_VAL_INT;
> +	case IIO_CHAN_INFO_SCALE:
> +		*val = regulator_get_voltage(priv->vref_reg);
> +		if (*val < 0) {
> +			dev_err(&priv->spi->dev, "failed to read vref regulator: %d\n",
> +					*val);
> +			return *val;
> +		}
> +
> +		/* Convert to mV */
> +		*val /= 1000;
> +		*val2 = chan->scan_type.realbits;
> +		return IIO_VAL_FRACTIONAL_LOG2;
> +	default:
> +		return -EINVAL;
> +	}
> +}
> +
> +static int ltc1660_write_raw(struct iio_dev *indio_dev,
> +		struct iio_chan_spec const *chan,
> +		int val,
> +		int val2,
> +		long mask)
> +{
> +	struct ltc1660_priv *priv = iio_priv(indio_dev);
> +	int ret;
> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_RAW:
> +		if (val2 != 0)
> +			return -EINVAL;
> +
> +		if (val < 0 || val > GENMASK(chan->scan_type.realbits - 1, 0))
> +			return -EINVAL;
> +
> +		ret = regmap_write(priv->regmap, chan->channel,
> +					(val << chan->scan_type.shift));
> +		if (!ret)
> +			priv->value[chan->channel] = val;
> +
> +		return ret;
> +	default:
> +		return -EINVAL;
> +	}
> +}
> +
> +#define LTC1660_CHAN(chan, bits) {			\
> +	.type = IIO_VOLTAGE,				\
> +	.indexed = 1,					\
> +	.output = 1,					\
> +	.channel = chan,				\
> +	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),	\
> +	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),	\
> +	.scan_type = {					\
> +		.sign = 'u',				\
> +		.realbits = (bits),			\
> +		.storagebits = 16,			\
> +		.shift = 12 - (bits),			\
> +	},						\
> +}
> +
> +#define  LTC1660_OCTAL_CHANNELS(bits) {			\
> +		LTC1660_CHAN(LTC1660_REG_DAC_A, bits),	\
> +		LTC1660_CHAN(LTC1660_REG_DAC_B, bits),	\
> +		LTC1660_CHAN(LTC1660_REG_DAC_C, bits),	\
> +		LTC1660_CHAN(LTC1660_REG_DAC_D, bits),	\
> +		LTC1660_CHAN(LTC1660_REG_DAC_E, bits),	\
> +		LTC1660_CHAN(LTC1660_REG_DAC_F, bits),	\
> +		LTC1660_CHAN(LTC1660_REG_DAC_G, bits),	\
> +		LTC1660_CHAN(LTC1660_REG_DAC_H, bits),	\
> +}
> +
> +static const struct iio_chan_spec ltc1660_channels[][LTC1660_NUM_CHANNELS] = {
> +	[ID_LTC1660] = LTC1660_OCTAL_CHANNELS(10),
> +	[ID_LTC1665] = LTC1660_OCTAL_CHANNELS(8),
> +};
> +
> +static const struct iio_info ltc1660_info = {
> +	.read_raw = &ltc1660_read_raw,
> +	.write_raw = &ltc1660_write_raw,
> +};
> +
> +static int __maybe_unused ltc1660_suspend(struct device *dev)
> +{
> +	struct ltc1660_priv *priv = iio_priv(spi_get_drvdata(
> +						to_spi_device(dev)));
> +	return regmap_write(priv->regmap, LTC1660_REG_SLEEP, 0x00);
> +}
> +
> +static int __maybe_unused ltc1660_resume(struct device *dev)
> +{
> +	struct ltc1660_priv *priv = iio_priv(spi_get_drvdata(
> +						to_spi_device(dev)));
> +	return regmap_write(priv->regmap, LTC1660_REG_WAKE, 0x00);
> +}
> +static SIMPLE_DEV_PM_OPS(ltc1660_pm_ops, ltc1660_suspend, ltc1660_resume);
> +
> +static int ltc1660_probe(struct spi_device *spi)
> +{
> +	struct iio_dev *indio_dev;
> +	struct ltc1660_priv *priv;
> +	const struct spi_device_id *id = spi_get_device_id(spi);
> +	int ret;
> +
> +	indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*priv));
> +	if (indio_dev == NULL)
> +		return -ENOMEM;
> +
> +	priv = iio_priv(indio_dev);
> +	priv->regmap = devm_regmap_init_spi(spi, &ltc1660_regmap_config);
> +	if (IS_ERR(priv->regmap)) {
> +		dev_err(&spi->dev, "failed to register spi regmap %ld\n",
> +			PTR_ERR(priv->regmap));
> +		return PTR_ERR(priv->regmap);
> +	}
> +
> +	priv->vref_reg = devm_regulator_get(&spi->dev, "vref");
> +	if (IS_ERR(priv->vref_reg)) {
> +		dev_err(&spi->dev, "vref regulator not specified\n");
> +		return PTR_ERR(priv->vref_reg);
> +	}
> +
> +	ret = regulator_enable(priv->vref_reg);
> +	if (ret) {
> +		dev_err(&spi->dev, "failed to enable vref regulator: %d\n",
> +				ret);
> +		return ret;
> +	}
> +
> +	priv->spi = spi;
> +	spi_set_drvdata(spi, indio_dev);
> +	indio_dev->dev.parent = &spi->dev;
> +	indio_dev->info = &ltc1660_info;
> +	indio_dev->modes = INDIO_DIRECT_MODE;
> +	indio_dev->channels = ltc1660_channels[id->driver_data];
> +	indio_dev->num_channels = LTC1660_NUM_CHANNELS;
> +	indio_dev->name = id->name;
> +
> +	ret = iio_device_register(indio_dev);
> +	if (ret) {
> +		dev_err(&spi->dev, "failed to register iio device: %d\n",
> +				ret);
> +		goto error_disable_reg;
> +	}
> +
> +	return 0;
> +
> +error_disable_reg:
> +	regulator_disable(priv->vref_reg);
> +
> +	return ret;
> +}
> +
> +static int ltc1660_remove(struct spi_device *spi)
> +{
> +	struct iio_dev *indio_dev = spi_get_drvdata(spi);
> +	struct ltc1660_priv *priv = iio_priv(indio_dev);
> +
> +	iio_device_unregister(indio_dev);
> +	regulator_disable(priv->vref_reg);
> +
> +	return 0;
> +}
> +
> +static const struct of_device_id ltc1660_dt_ids[] = {
> +	{ .compatible = "lltc,ltc1660", .data = (void *)ID_LTC1660 },
> +	{ .compatible = "lltc,ltc1665", .data = (void *)ID_LTC1665 },
> +	{ /* sentinel */ }
> +};
> +MODULE_DEVICE_TABLE(of, ltc1660_dt_ids);
> +
> +static const struct spi_device_id ltc1660_id[] = {
> +	{"ltc1660", ID_LTC1660},
> +	{"ltc1665", ID_LTC1665},
> +	{ /* sentinel */ }
> +};
> +MODULE_DEVICE_TABLE(spi, ltc1660_id);
> +
> +static struct spi_driver ltc1660_driver = {
> +	.driver = {
> +		.name = "ltc1660",
> +		.of_match_table = ltc1660_dt_ids,
> +		.pm = &ltc1660_pm_ops,
> +	},
> +	.probe	= ltc1660_probe,
> +	.remove = ltc1660_remove,
> +	.id_table = ltc1660_id,
> +};
> +module_spi_driver(ltc1660_driver);
> +
> +MODULE_AUTHOR("Marcus Folkesson <marcus.folkesson@gmail.com>");
> +MODULE_DESCRIPTION("Linear Technology LTC1660/LTC1665 DAC");
> +MODULE_LICENSE("GPL v2");