linux-kernel - Re: [PATCH v4 5/5] iio: dac: ltc2664: Add driver for LTC2664 and LTC2672

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Date: Wed, 26 Jun 2024 13:14:32 +0200
From: Nuno Sá <noname.nuno@...il.com>
To: Kim Seer Paller <kimseer.paller@...log.com>,
 linux-kernel@...r.kernel.org,  linux-iio@...r.kernel.org,
 devicetree@...r.kernel.org
Cc: Jonathan Cameron <jic23@...nel.org>, David Lechner
 <dlechner@...libre.com>,  Lars-Peter Clausen <lars@...afoo.de>, Liam
 Girdwood <lgirdwood@...il.com>, Mark Brown <broonie@...nel.org>, Dimitri
 Fedrau <dima.fedrau@...il.com>, Krzysztof Kozlowski <krzk+dt@...nel.org>,
 Rob Herring <robh@...nel.org>, Conor Dooley <conor+dt@...nel.org>,  Michael
 Hennerich <michael.hennerich@...log.com>
Subject: Re: [PATCH v4 5/5] iio: dac: ltc2664: Add driver for LTC2664 and
 LTC2672

On Wed, 2024-06-19 at 14:49 +0800, Kim Seer Paller wrote:
> LTC2664 4 channel, 12-/16-Bit Voltage Output SoftSpan DAC
> LTC2672 5 channel, 12-/16-Bit Current Output Softspan DAC
> 
> Co-developed-by: Michael Hennerich <michael.hennerich@...log.com>
> Signed-off-by: Michael Hennerich <michael.hennerich@...log.com>
> Signed-off-by: Kim Seer Paller <kimseer.paller@...log.com>
> ---

Just minor nits... Anyways:

Reviewed-by: Nuno Sa <nuno.sa@...log.com>

>  MAINTAINERS               |   1 +
>  drivers/iio/dac/Kconfig   |  11 +
>  drivers/iio/dac/Makefile  |   1 +
>  drivers/iio/dac/ltc2664.c | 755 ++++++++++++++++++++++++++++++++++++++
>  4 files changed, 768 insertions(+)
>  create mode 100644 drivers/iio/dac/ltc2664.c
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index f4a5b5bc8ccc..7a02d9a196fb 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -13082,6 +13082,7 @@ S:	Supported
>  W:	https://ez.analog.com/linux-software-drivers
>  F:	Documentation/devicetree/bindings/iio/dac/adi,ltc2664.yaml
>  F:	Documentation/devicetree/bindings/iio/dac/adi,ltc2672.yaml
> +F:	drivers/iio/dac/ltc2664.c
>  
>  LTC2688 IIO DAC DRIVER
>  M:	Nuno Sá <nuno.sa@...log.com>
> diff --git a/drivers/iio/dac/Kconfig b/drivers/iio/dac/Kconfig
> index fb48dddbcc20..3a7691db3998 100644
> --- a/drivers/iio/dac/Kconfig
> +++ b/drivers/iio/dac/Kconfig
> @@ -371,6 +371,17 @@ config LTC2632
>  	  To compile this driver as a module, choose M here: the
>  	  module will be called ltc2632.
>  
> +config LTC2664
> +	tristate "Analog Devices LTC2664 and LTC2672 DAC SPI driver"
> +	depends on SPI
> +	select REGMAP
> +	help
> +	  Say yes here to build support for Analog Devices
> +	  LTC2664 and LTC2672 converters (DAC).
> +
> +	  To compile this driver as a module, choose M here: the
> +	  module will be called ltc2664.
> +
>  config M62332
>  	tristate "Mitsubishi M62332 DAC driver"
>  	depends on I2C
> diff --git a/drivers/iio/dac/Makefile b/drivers/iio/dac/Makefile
> index 8432a81a19dc..2cf148f16306 100644
> --- a/drivers/iio/dac/Makefile
> +++ b/drivers/iio/dac/Makefile
> @@ -37,6 +37,7 @@ obj-$(CONFIG_DS4424) += ds4424.o
>  obj-$(CONFIG_LPC18XX_DAC) += lpc18xx_dac.o
>  obj-$(CONFIG_LTC1660) += ltc1660.o
>  obj-$(CONFIG_LTC2632) += ltc2632.o
> +obj-$(CONFIG_LTC2664) += ltc2664.o
>  obj-$(CONFIG_LTC2688) += ltc2688.o
>  obj-$(CONFIG_M62332) += m62332.o
>  obj-$(CONFIG_MAX517) += max517.o
> diff --git a/drivers/iio/dac/ltc2664.c b/drivers/iio/dac/ltc2664.c
> new file mode 100644
> index 000000000000..9b73b9c6a7a7
> --- /dev/null
> +++ b/drivers/iio/dac/ltc2664.c
> @@ -0,0 +1,755 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * LTC2664 4 channel, 12-/16-Bit Voltage Output SoftSpan DAC driver
> + * LTC2672 5 channel, 12-/16-Bit Current Output Softspan DAC driver
> + *
> + * Copyright 2024 Analog Devices Inc.
> + */
> +
> 

...

> +
> +static int ltc2664_dac_code_read(struct ltc2664_state *st, u32 chan, u32
> input,
> +				 u32 *code)
> +{
> +	guard(mutex)(&st->lock);
> +	*code = st->channels[chan].raw[input];
> +
> +	return 0;

no need for an error code...

...

> 
> +static int ltc2664_probe(struct spi_device *spi)
> +{
> +	static const char * const regulators[] = { "vcc", "iovcc", "v-neg" };
> +	const struct ltc2664_chip_info *chip_info;
> +	struct device *dev = &spi->dev;
> +	struct iio_dev *indio_dev;
> +	struct ltc2664_state *st;
> +	int ret;
> +
> +	indio_dev = devm_iio_device_alloc(dev, sizeof(*st));
> +	if (!indio_dev)
> +		return -ENOMEM;
> +
> +	st = iio_priv(indio_dev);
> +	st->spi = spi;
> +
> +	chip_info = spi_get_device_match_data(spi);
> +	if (!chip_info)
> +		return -ENODEV;
> +
> +	st->chip_info = chip_info;
> +
> +	mutex_init(&st->lock);
> +
> +	st->regmap = devm_regmap_init_spi(spi, &ltc2664_regmap_config);
> +	if (IS_ERR(st->regmap))
> +		return dev_err_probe(dev, PTR_ERR(st->regmap),
> +				     "Failed to init regmap");
> +
> +	ret = devm_regulator_bulk_get_enable(dev, ARRAY_SIZE(regulators),
> +					     regulators);
> +	if (ret)
> +		return dev_err_probe(dev, ret, "Failed to enable
> regulators\n");
> +
> +	ret = devm_regulator_get_enable_read_voltage(dev, "ref");
> +	if (ret < 0)
> +		return dev_err_probe(dev, ret, "Failed to get vref
> voltage\n");
> +	else if (ret == -ENODEV)
> +		st->vref_mv = chip_info->internal_vref_mv;
> +	else
> +		st->vref_mv = ret / 1000;

This could be:
if (ret < 0 && ret != -ENODEV)
	return ret;

st->vref_mv = ret > 0 ? ret / 1000 :  chip_info->internal_vref_mv;

- Nuno Sá