Re: [PATCH v2 5/9] iio: adc: adi-axi-adc: Add platform children support

[Jonathan Cameron <jic23@kernel.org>]

On Tue, 10 Dec 2024 10:46:45 +0000
Guillaume Stols <gstols@baylibre.com> wrote:

> This is a preparation for the next commit adding support for register
> read and write functions on AD7606.
> Since sometimes a bus will be used, it has been agreed during ad3552's
> driver implementation that the device's driver bus is the backend, whose
> device node will be a child node.
> To provide the special callbacks for setting the register, axi-adc needs
> to pass them to the child device's driver through platform data.
> 
> Signed-off-by: Guillaume Stols <gstols@baylibre.com>
> ---
>  drivers/iio/adc/adi-axi-adc.c | 75 +++++++++++++++++++++++++++++++++++++++++--
>  1 file changed, 72 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/iio/adc/adi-axi-adc.c b/drivers/iio/adc/adi-axi-adc.c
> index c7357601f0f8..7ff636643e56 100644
> --- a/drivers/iio/adc/adi-axi-adc.c
> +++ b/drivers/iio/adc/adi-axi-adc.c
> @@ -80,7 +80,18 @@
>  	 ADI_AXI_REG_CHAN_CTRL_FMT_EN |		\
>  	 ADI_AXI_REG_CHAN_CTRL_ENABLE)
>  
> +struct axi_adc_info {
> +	unsigned int version;
> +	const struct iio_backend_info *backend_info;
> +	bool bus_controller;
> +	const void *pdata;
> +	unsigned int pdata_sz;
> +};
> +
>  struct adi_axi_adc_state {
> +	/* Target ADC platform device */
> +	struct platform_device *adc_pdev;
> +	const struct axi_adc_info *info;
>  	struct regmap *regmap;
>  	struct device *dev;
>  	/* lock to protect multiple accesses to the device registers */
> @@ -325,6 +336,40 @@ static const struct regmap_config axi_adc_regmap_config = {
>  	.reg_stride = 4,
>  };
>  
> +static void axi_adc_child_remove(void *data)
> +{
> +	struct adi_axi_adc_state *st = data;

With changes suggested below, the parameter becomes the pdev itself
and you can do this a one liner as we don't need the local variable.

> +
> +	platform_device_unregister(st->adc_pdev);
> +}
> +
> +static int axi_adc_create_platform_device(struct adi_axi_adc_state *st,
> +					  struct fwnode_handle *child)
> +{
> +	struct platform_device_info pi = {
> +		.parent = st->dev,
> +		.name = fwnode_get_name(child),
> +		.id = PLATFORM_DEVID_AUTO,
> +		.fwnode = child,
> +		.data = st->info->pdata,
> +		.size_data = st->info->pdata_sz,
> +	};
> +	struct platform_device *pdev;
> +	int ret;
> +
> +	pdev = platform_device_register_full(&pi);
> +	if (IS_ERR(pdev))
> +		return PTR_ERR(pdev);
> +
> +	st->adc_pdev = pdev;
> +
> +	ret = devm_add_action_or_reset(st->dev, axi_adc_child_remove, st);
I'd be tempted to move this up above setting of st->adc_pdev and use
the pdev pointer as the parameter.

That way we don't end up with slightly odd (though harmless)
case of st->adc_pdev set to state data if we hit the error path and have
unregistered it.

> +	if (ret)
> +		return ret;
> +
> +	return 0;
> +}
> +
>  static const struct iio_backend_ops adi_axi_adc_ops = {
>  	.enable = axi_adc_enable,
>  	.disable = axi_adc_disable,
> @@ -370,7 +415,9 @@ static int adi_axi_adc_probe(struct platform_device *pdev)
>  		return dev_err_probe(&pdev->dev, PTR_ERR(st->regmap),
>  				     "failed to init register map\n");
>  
> -	expected_ver = device_get_match_data(&pdev->dev);
> +	st->info = device_get_match_data(&pdev->dev);
> +
> +	expected_ver = &st->info->version;
>  	if (!expected_ver)

That check is wrong.  It's st->info that in theory might not be set
(in practice it always is, but the check is meant to be on devie_get_match_data
result).


>  		return -ENODEV;
>  
> @@ -408,6 +455,25 @@ static int adi_axi_adc_probe(struct platform_device *pdev)
>  		return dev_err_probe(&pdev->dev, ret,
>  				     "failed to register iio backend\n");
>  
> +	if (st->info->bus_controller) {
> +		device_for_each_child_node_scoped(&pdev->dev, child) {
> +			int val;
> +
> +			/* Processing only reg 0 node */
> +			ret = fwnode_property_read_u32(child, "reg", &val);
> +			if (ret || val != 0)
> +				continue;
> +			ret = fwnode_property_read_u32(child, "io-backends",
> +						       &val);
> +			if (ret)
> +				continue;
> +
> +			ret = axi_adc_create_platform_device(st, child);
> +			if (ret)
> +				continue;

You continue either way, so unless there will be more code here to come, just
don't check ret.

			/* Continue even on error */
			axi_adc_create_platform_device(st, child);

However, I'm not sure why it makes sense to carry on if this has failed.


> +		}
> +	}
> +
>  	dev_info(&pdev->dev, "AXI ADC IP core (%d.%.2d.%c) probed\n",
>  		 ADI_AXI_PCORE_VER_MAJOR(ver),
>  		 ADI_AXI_PCORE_VER_MINOR(ver),
> @@ -416,11 +482,14 @@ static int adi_axi_adc_probe(struct platform_device *pdev)
>  	return 0;
>  }
>  
> -static unsigned int adi_axi_adc_10_0_a_info = ADI_AXI_PCORE_VER(10, 0, 'a');
> +static const struct axi_adc_info adc_generic = {
> +	.version = ADI_AXI_PCORE_VER(10, 0, 'a'),
> +	.backend_info = &adi_axi_adc_generic,
> +};
>  
>  /* Match table for of_platform binding */
>  static const struct of_device_id adi_axi_adc_of_match[] = {
> -	{ .compatible = "adi,axi-adc-10.0.a", .data = &adi_axi_adc_10_0_a_info },
> +	{ .compatible = "adi,axi-adc-10.0.a", .data = &adc_generic },
>  	{ /* end of list */ }
>  };
>  MODULE_DEVICE_TABLE(of, adi_axi_adc_of_match);
>