linux-kernel - Re: [PATCH v7 8/8] iio: dac: adi-axi-dac: add registering of child fdt node

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Message-ID: <8cba678ee61eb221f8d5deb786a69b547371f11c.camel@gmail.com>
Date: Tue, 22 Oct 2024 14:02:44 +0200
From: Nuno Sá <noname.nuno@...il.com>
To: Angelo Dureghello <adureghello@...libre.com>, Nuno Sá
	 <nuno.sa@...log.com>, Lars-Peter Clausen <lars@...afoo.de>, Michael
 Hennerich	 <Michael.Hennerich@...log.com>, Jonathan Cameron
 <jic23@...nel.org>, Rob Herring <robh@...nel.org>, Krzysztof Kozlowski
 <krzk+dt@...nel.org>, Conor Dooley	 <conor+dt@...nel.org>, Olivier Moysan
 <olivier.moysan@...s.st.com>
Cc: linux-iio@...r.kernel.org, devicetree@...r.kernel.org, 
	linux-kernel@...r.kernel.org, dlechner@...libre.com, Mark Brown
	 <broonie@...nel.org>
Subject: Re: [PATCH v7 8/8] iio: dac: adi-axi-dac: add registering of child
 fdt node

On Mon, 2024-10-21 at 14:40 +0200, Angelo Dureghello wrote:
> From: Angelo Dureghello <adureghello@...libre.com>
> 
> Change to obtain the fdt use case as reported in the
> adi,ad3552r.yaml file in this patchset.
> 
> The DAC device is defined as a child node of the backend.
> Registering the child fdt node as a platform devices.
> 
> Signed-off-by: Angelo Dureghello <adureghello@...libre.com>
> ---
>  drivers/iio/dac/adi-axi-dac.c | 53
> +++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 53 insertions(+)
> 
> diff --git a/drivers/iio/dac/adi-axi-dac.c b/drivers/iio/dac/adi-axi-dac.c
> index 9d6809fe7a67..7f7ef3e219ba 100644
> --- a/drivers/iio/dac/adi-axi-dac.c
> +++ b/drivers/iio/dac/adi-axi-dac.c
> @@ -29,6 +29,8 @@
>  #include <linux/iio/buffer.h>
>  #include <linux/iio/iio.h>
>  
> +#include "ad3552r-hs.h"
> +
>  /*
>   * Register definitions:
>   *   https://wiki.analog.com/resources/fpga/docs/axi_dac_ip#register_map
> @@ -97,6 +99,7 @@ struct axi_dac_info {
>  	unsigned int version;
>  	const struct iio_backend_info *backend_info;
>  	bool has_dac_clk;
> +	bool has_child_nodes;
>  };
>  
>  struct axi_dac_state {
> @@ -723,6 +726,35 @@ static int axi_dac_bus_reg_read(struct iio_backend *back,
> u32 reg, u32 *val,
>  	return regmap_read(st->regmap, AXI_DAC_CUSTOM_RD_REG, val);
>  }
>  
> +static void axi_dac_child_remove(void *data)
> +{
> +	platform_device_unregister(data);
> +}
> +
> +static int axi_dac_create_platform_device(struct axi_dac_state *st,
> +					  struct fwnode_handle *child)
> +{
> +	struct ad3552r_hs_platform_data pdata = {
> +		.bus_reg_read = axi_dac_bus_reg_read,
> +		.bus_reg_write = axi_dac_bus_reg_write,
> +	};
> +	struct platform_device_info pi = {
> +		.parent = st->dev,
> +		.name = fwnode_get_name(child),
> +		.id = PLATFORM_DEVID_AUTO,
> +		.fwnode = child,
> +		.data = &pdata,
> +		.size_data = sizeof(pdata),
> +	};
> +	struct platform_device *pdev;
> +
> +	pdev = platform_device_register_full(&pi);
> +	if (IS_ERR(pdev))
> +		return PTR_ERR(pdev);
> +
> +	return devm_add_action_or_reset(st->dev, axi_dac_child_remove, pdev);
> +}
> +
>  static const struct iio_backend_ops axi_dac_generic_ops = {
>  	.enable = axi_dac_enable,
>  	.disable = axi_dac_disable,
> @@ -865,6 +897,26 @@ static int axi_dac_probe(struct platform_device *pdev)
>  		return dev_err_probe(&pdev->dev, ret,
>  				     "failed to register iio backend\n");
>  
> +	if (st->info->has_child_nodes) {

I would prefer to not be silent on possible misconfigurations. IOW, moving the
check inside the loop and error out if (!st->info->has_child_nodes)

- Nuno Sá