On Mon, 24 Feb 2025 20:33:16 +0200
Matti Vaittinen <mazziesaccount@xxxxxxxxx> wrote:
> There are ADC ICs which may have some of the AIN pins usable for other
> functions. These ICs may have some of the AIN pins wired so that they
> should not be used for ADC.
>
> (Preferred?) way for marking pins which can be used as ADC inputs is to
> add corresponding channels@N nodes in the device tree as described in
> the ADC binding yaml.
>
> Add couple of helper functions which can be used to retrieve the channel
> information from the device node.
>
> Signed-off-by: Matti Vaittinen <mazziesaccount@xxxxxxxxx>
>
> ---
> Revision history:
> v3 => v4:
> - Drop diff-channel support
> - Drop iio_adc_device_channels_by_property()
> - Add IIO_DEVICE namespace
> - Move industrialio-adc.o to top of the Makefile
> - Some styling as suggested by Andy
> - Re-consider included headers
> v2 => v3: Mostly based on review comments by Jonathan
> - Support differential and single-ended channels
> - Rename iio_adc_device_get_channels() as
> iio_adc_device_channels_by_property()
> - Improve spelling
> - Drop support for cases where DT comes from parent device's node
> - Decrease loop indent by reverting node name check conditions
> - Don't set 'chan->indexed' by number of channels to keep the
> interface consistent no matter how many channels are connected.
> - Fix ID range check and related comment
> RFC v1 => v2:
> - New patch
>
> iio: adc: helper: drop headers
> ---
> drivers/iio/adc/Kconfig | 3 +
> drivers/iio/adc/Makefile | 2 +
> drivers/iio/adc/industrialio-adc.c | 89 ++++++++++++++++++++++++++++++
> include/linux/iio/adc-helpers.h | 22 ++++++++
> 4 files changed, 116 insertions(+)
> create mode 100644 drivers/iio/adc/industrialio-adc.c
> create mode 100644 include/linux/iio/adc-helpers.h
>
> diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
> index 849c90203071..37b70a65da6f 100644
> --- a/drivers/iio/adc/Kconfig
> +++ b/drivers/iio/adc/Kconfig
> @@ -6,6 +6,9 @@
>
> menu "Analog to digital converters"
>
> +config IIO_ADC_HELPER
> + tristate
> +
> config AB8500_GPADC
> bool "ST-Ericsson AB8500 GPADC driver"
> depends on AB8500_CORE && REGULATOR_AB8500
> diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
> index ee19afba62b7..1c410f483029 100644
> --- a/drivers/iio/adc/Makefile
> +++ b/drivers/iio/adc/Makefile
> @@ -3,6 +3,8 @@
> # Makefile for IIO ADC drivers
> #
>
> +obj-$(CONFIG_IIO_ADC_HELPER) += industrialio-adc.o
> +
> # When adding new entries keep the list in alphabetical order
> obj-$(CONFIG_AB8500_GPADC) += ab8500-gpadc.o
> obj-$(CONFIG_AD_SIGMA_DELTA) += ad_sigma_delta.o
> diff --git a/drivers/iio/adc/industrialio-adc.c b/drivers/iio/adc/industrialio-adc.c
> new file mode 100644
> index 000000000000..d8e9e6825d2b
> --- /dev/null
> +++ b/drivers/iio/adc/industrialio-adc.c
> @@ -0,0 +1,89 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Helpers for parsing common ADC information from a firmware node.
> + *
> + * Copyright (c) 2025 Matti Vaittinen <mazziesaccount@xxxxxxxxx>
> + */
> +
> +#include <linux/device.h>
> +#include <linux/errno.h>
> +#include <linux/export.h>
> +#include <linux/module.h>
> +#include <linux/property.h>
> +#include <linux/types.h>
> +
> +#include <linux/iio/adc-helpers.h>
> +#include <linux/iio/iio.h>
> +
> +int iio_adc_device_num_channels(struct device *dev)
> +{
> + return device_get_child_node_count_named(dev, "channel");
> +}
> +EXPORT_SYMBOL_GPL(iio_adc_device_num_channels);
Just noticed, this isn't namespaces which is a bit odd. I'd drop
the export anyway in favour of static inline but if you don't match
the namespace of the next one.
