Re: [PATCH v4 04/10] iio: adc: rzg2l_adc: Use adc-helpers

[Jonathan Cameron <jic23@kernel.org>]

On Mon, 24 Feb 2025 20:33:29 +0200
Matti Vaittinen <mazziesaccount@gmail.com> wrote:

> The new devm_iio_adc_device_alloc_chaninfo() -helper is intended to help
> drivers avoid open-coding the for_each_node -loop for getting the
> channel IDs. The helper provides standard way to detect the ADC channel
> nodes (by the node name), and a standard way to convert the "reg",
> "diff-channels", "single-channel" and the "common-mode-channel" to
> channel identification numbers used in the struct iio_chan_spec.

Needs an update to reflecting naming and functionality simplifications.

> Furthermore, the helper checks the ID is in range of 0 ... num-channels.
> 
> The original driver treated all found child nodes as channel nodes. The
> new helper requires channel nodes to be named channel[@N]. This should
> help avoid problems with devices which may contain also other but ADC
> child nodes. Quick grep from arch/* with the rzg2l_adc's compatible
> string didn't reveal any in-tree .dts with channel nodes named
> othervice. Also, same grep shows all the .dts seem to have channel IDs
otherwise

(othervice does sound cool though ;)

> between 0..num of channels.
> 
> Use the new helper.
> 
> Signed-off-by: Matti Vaittinen <mazziesaccount@gmail.com>
> 
> ---
> Revision history:
> v3 => v4:
>  - Adapt to 'drop diff-channel support' changes to ADC-helpers
>  - select ADC helpers in the Kconfig
>  - Rebased to 6.14-rc3 => channel type can no longer come from the
>    template.
> 
> v2 => v3:
>  - New patch
> 
> I picked the rzg2l_adc in this series because it has a straightforward
> approach for populating the struct iio_chan_spec. Only other member
> in the stuct besides the .channel, which can't use a 'template' -data,
> is the .datasheet_name. This makes the rzg2l_adc well suited for example
> user of this new helper. I hope this patch helps to evaluate whether these
> helpers are worth the hassle.
This doesn't seem to match driver. It is messing with channel type.

> 
> The change is compile tested only!! Testing before applying is highly
> appreciated (as always!).
> ---
>  drivers/iio/adc/Kconfig     |  1 +
>  drivers/iio/adc/rzg2l_adc.c | 38 +++++++++++++++++--------------------
>  2 files changed, 18 insertions(+), 21 deletions(-)
> 
> diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
> index 37b70a65da6f..e4933de0c366 100644
> --- a/drivers/iio/adc/Kconfig
> +++ b/drivers/iio/adc/Kconfig
> @@ -1222,6 +1222,7 @@ config RICHTEK_RTQ6056
>  config RZG2L_ADC
>  	tristate "Renesas RZ/G2L ADC driver"
>  	depends on ARCH_RZG2L || COMPILE_TEST
> +	select IIO_ADC_HELPER
>  	help
>  	  Say yes here to build support for the ADC found in Renesas
>  	  RZ/G2L family.
> diff --git a/drivers/iio/adc/rzg2l_adc.c b/drivers/iio/adc/rzg2l_adc.c
> index 883c167c0670..51c87b1bdc98 100644
> --- a/drivers/iio/adc/rzg2l_adc.c
> +++ b/drivers/iio/adc/rzg2l_adc.c
> @@ -11,6 +11,7 @@
>  #include <linux/cleanup.h>
>  #include <linux/completion.h>
>  #include <linux/delay.h>
> +#include <linux/iio/adc-helpers.h>
>  #include <linux/iio/iio.h>
>  #include <linux/interrupt.h>
>  #include <linux/io.h>
> @@ -324,21 +325,30 @@ static irqreturn_t rzg2l_adc_isr(int irq, void *dev_id)
>  	return IRQ_HANDLED;
>  }
>  
> +static const struct iio_chan_spec rzg2l_adc_chan_template = {
> +	.indexed = 1,
> +	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
> +};
> +
>  static int rzg2l_adc_parse_properties(struct platform_device *pdev, struct rzg2l_adc *adc)
>  {
>  	const struct rzg2l_adc_hw_params *hw_params = adc->hw_params;
>  	struct iio_chan_spec *chan_array;
>  	struct rzg2l_adc_data *data;
> -	unsigned int channel;
>  	int num_channels;
> -	int ret;
>  	u8 i;
>  
>  	data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
>  	if (!data)
>  		return -ENOMEM;
>  
> -	num_channels = device_get_child_node_count(&pdev->dev);
> +	num_channels = devm_iio_adc_device_alloc_chaninfo_se(&pdev->dev,
> +						&rzg2l_adc_chan_template,
> +						hw_params->num_channels - 1,
> +						&chan_array);
> +	if (num_channels < 0)
> +		return num_channels;
> +
>  	if (!num_channels)
>  		return dev_err_probe(&pdev->dev, -ENODEV, "no channel children\n");
>  
> @@ -346,26 +356,11 @@ static int rzg2l_adc_parse_properties(struct platform_device *pdev, struct rzg2l
>  		return dev_err_probe(&pdev->dev, -EINVAL,
>  				     "num of channel children out of range\n");
>  
> -	chan_array = devm_kcalloc(&pdev->dev, num_channels, sizeof(*chan_array),
> -				  GFP_KERNEL);
> -	if (!chan_array)
> -		return -ENOMEM;
> -
> -	i = 0;
> -	device_for_each_child_node_scoped(&pdev->dev, fwnode) {
> -		ret = fwnode_property_read_u32(fwnode, "reg", &channel);
> -		if (ret)
> -			return ret;
> -
> -		if (channel >= hw_params->num_channels)
> -			return -EINVAL;
> +	for (i = 0; i < num_channels; i++) {
> +		int channel = chan_array[i].channel;
>  
> -		chan_array[i].type = rzg2l_adc_channels[channel].type;
> -		chan_array[i].indexed = 1;
> -		chan_array[i].channel = channel;
> -		chan_array[i].info_mask_separate = BIT(IIO_CHAN_INFO_RAW);
>  		chan_array[i].datasheet_name = rzg2l_adc_channels[channel].name;
> -		i++;
> +		chan_array[i].type = rzg2l_adc_channels[channel].type;
>  	}
>  
>  	data->num_channels = num_channels;
> @@ -626,3 +621,4 @@ module_platform_driver(rzg2l_adc_driver);
>  MODULE_AUTHOR("Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>");
>  MODULE_DESCRIPTION("Renesas RZ/G2L ADC driver");
>  MODULE_LICENSE("GPL v2");
> +MODULE_IMPORT_NS("IIO_DRIVER");