linux-kernel - Re: [PATCH 3/4] iio: adc: Add support for the GE HealthCare PMC ADC

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Message-ID: <20241001202430.19bfc666@jic23-huawei>
Date: Tue, 1 Oct 2024 20:24:30 +0100
From: Jonathan Cameron <jic23@...nel.org>
To: Herve Codina <herve.codina@...tlin.com>
Cc: Lars-Peter Clausen <lars@...afoo.de>, Rob Herring <robh@...nel.org>,
 Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley
 <conor+dt@...nel.org>, linux-iio@...r.kernel.org,
 devicetree@...r.kernel.org, linux-kernel@...r.kernel.org, Luca Ceresoli
 <luca.ceresoli@...tlin.com>, Ian Ray <ian.ray@...ealthcare.com>, Thomas
 Petazzoni <thomas.petazzoni@...tlin.com>
Subject: Re: [PATCH 3/4] iio: adc: Add support for the GE HealthCare PMC ADC

On Tue,  1 Oct 2024 09:46:17 +0200
Herve Codina <herve.codina@...tlin.com> wrote:

> The GE HealthCare PMC Analog to Digital Converter (ADC) is a 16-Channel
> (voltage and current), 16-Bit ADC with an I2C Interface.
> 
> Signed-off-by: Herve Codina <herve.codina@...tlin.com>

Just one thing to add to David's review.

I'm going to guess this isn't a general purpose ADC? Can you share any info
on what sort of device it is used in?

No problem if not - I'm just curious as I've not seen GE HealthCare I2C parts
before!

> diff --git a/drivers/iio/adc/gehc-pmc-adc.c b/drivers/iio/adc/gehc-pmc-adc.c
> new file mode 100644
> index 000000000000..c46c2fb84d35
> --- /dev/null
> +++ b/drivers/iio/adc/gehc-pmc-adc.c
> @@ -0,0 +1,233 @@


> +
> +static int pmc_adc_read_raw(struct iio_dev *indio_dev, struct iio_chan_spec const *chan,
> +			    int *val, int *val2, long mask)
> +{
> +	struct pmc_adc *pmc_adc = iio_priv(indio_dev);
> +	int ret;
> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_RAW:
> +		ret = pmc_adc_read_raw_ch(pmc_adc, chan->address, val);
> +		if (ret)
> +			return ret;
> +		return IIO_VAL_INT;
> +
> +	case IIO_CHAN_INFO_SCALE:
> +		*val = 1; /* Raw values are directly read in mV or mA */

Drop this scale and make the channels processed. That saves userspace even applying
the *1 this indicates.  Rare to find a device that outputs in our base units
but might as well take advantage of one that does :)

> +		return IIO_VAL_INT;
> +	}
> +
> +	return -EINVAL;
> +}