linux-kernel - Re: [PATCH v2 2/2] iio: adc: Add support for AD4000

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Date: Sat, 13 Apr 2024 17:39:32 +0100
From: Jonathan Cameron <jic23@...nel.org>
To: Marcelo Schmitt <marcelo.schmitt@...log.com>
Cc: <lars@...afoo.de>, <Michael.Hennerich@...log.com>, <robh+dt@...nel.org>,
 <krzysztof.kozlowski+dt@...aro.org>, <conor+dt@...nel.org>,
 <marcelo.schmitt1@...il.com>, <linux-iio@...r.kernel.org>,
 <devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 2/2] iio: adc: Add support for AD4000

On Mon, 8 Apr 2024 11:31:42 -0300
Marcelo Schmitt <marcelo.schmitt@...log.com> wrote:

> Add support for AD4000 family of low noise, low power, high speed,
> successive aproximation register (SAR) ADCs.
> 
> Signed-off-by: Marcelo Schmitt <marcelo.schmitt@...log.com>
A few trivial comments inline to add to David's much more thorough review.

> +#include <asm/unaligned.h>
> +#include <linux/bits.h>
> +#include <linux/bitfield.h>
> +#include <linux/device.h>
> +#include <linux/err.h>
> +#include <linux/kernel.h>
> +#include <linux/math.h>
> +#include <linux/module.h>
> +#include <linux/mod_devicetable.h>
> +#include <linux/gpio/consumer.h>
> +#include <linux/regulator/consumer.h>
> +#include <linux/spi/spi.h>
> +#include <linux/sysfs.h>
> +#include <linux/units.h>
> +#include <linux/util_macros.h>
> +#include <linux/iio/iio.h>
> +#include <linux/iio/sysfs.h>

You don't have custom attributes, so doubt you need that include.

> +#include <linux/iio/buffer.h>
> +#include <linux/iio/triggered_buffer.h>
> +#include <linux/iio/trigger_consumer.h>

> +
> +static int ad4000_read_raw(struct iio_dev *indio_dev,
> +			   struct iio_chan_spec const *chan, int *val,
> +			   int *val2, long info)
> +{
> +	struct ad4000_state *st = iio_priv(indio_dev);
> +
> +	switch (info) {
> +	case IIO_CHAN_INFO_RAW:
> +		iio_device_claim_direct_scoped(return -EBUSY, indio_dev)
> +			return ad4000_single_conversion(indio_dev, chan, val);
> +		unreachable();
> +	case IIO_CHAN_INFO_SCALE:
> +		*val = st->scale_tbl[st->pin_gain][st->span_comp][0];
> +		*val2 = st->scale_tbl[st->pin_gain][st->span_comp][1];
> +		return IIO_VAL_INT_PLUS_NANO;
> +	case IIO_CHAN_INFO_OFFSET:
> +		*val = 0;
> +		if (st->span_comp)
> +			*val = mult_frac(st->vref / 1000, 1, 10);
> +
> +		return IIO_VAL_INT;
> +	default:
> +		break;
> +	}
> +
> +	return -EINVAL;
As below - I'd push into the default: and drop down here.

> +}
> +
> +static int ad4000_read_avail(struct iio_dev *indio_dev,
> +			     struct iio_chan_spec const *chan,
> +			     const int **vals, int *type, int *length,
> +			     long info)
> +{
> +	struct ad4000_state *st = iio_priv(indio_dev);
> +
> +	switch (info) {
> +	case IIO_CHAN_INFO_SCALE:
> +		*vals = (int *)st->scale_tbl[st->pin_gain];
> +		*length = 2 * 2;
> +		*type = IIO_VAL_INT_PLUS_NANO;
> +		return IIO_AVAIL_LIST;
> +	default:
> +		return -EINVAL;
> +	}
> +}
> +
> +static int ad4000_write_raw_get_fmt(struct iio_dev *indio_dev,
> +				    struct iio_chan_spec const *chan, long mask)
> +{
> +	switch (mask) {
> +	case IIO_CHAN_INFO_SCALE:
> +		return IIO_VAL_INT_PLUS_NANO;
> +	default:
> +		return IIO_VAL_INT_PLUS_MICRO;
> +	}
> +	return -EINVAL;

dead code.

> +}
> +
> +static int ad4000_write_raw(struct iio_dev *indio_dev,
> +			    struct iio_chan_spec const *chan, int val, int val2,
> +			    long mask)
> +{
> +	struct ad4000_state *st = iio_priv(indio_dev);
> +	unsigned int reg_val;
> +	bool span_comp_en;
> +	int ret;
> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_SCALE:
> +		iio_device_claim_direct_scoped(return -EBUSY, indio_dev) {
> +			ret = ad4000_read_reg(st, &reg_val);
> +			if (ret < 0)
> +				return ret;
> +
> +			span_comp_en = (val2 == st->scale_tbl[st->pin_gain][1][1]);
> +			reg_val &= ~AD4000_SPAN_COMP;
> +			reg_val |= FIELD_PREP(AD4000_SPAN_COMP, span_comp_en);
> +
> +			ret = ad4000_write_reg(st, reg_val);
> +			if (ret < 0)
> +				return ret;
> +
> +			st->span_comp = span_comp_en;
> +			return 0;
> +		}
> +		unreachable();
> +	default:
> +		break;
> +	}
> +
> +	return -EINVAL;
Trivial but could push up into the default and make it clear there are no other ways out
of the switch statement.
> +}