Re: [PATCH v3 03/13] PCI: host-generic: Extract an ecam bridge creation helper from pci_host_common_probe()

[Manivannan Sadhasivam]

On Tue, Apr 01, 2025 at 10:17:03AM +0100, Marc Zyngier wrote:
> pci_host_common_probe() is an extremely userful helper, as it
> abstracts away most of the gunk that a "mostly-ECAM-compliant"
> device driver needs.
> 
> However, it is structured as a probe function, meaning that a lot
> of the driver-specific setup has to happen in a .init() callback,
> after the bridge and config space have been instantiated.
> 
> This is a bit awkward, and results in a number of convolutions
> that could be avoided if the host-common code was more like
> a library.
> 
> Introduce a pci_host_common_init() helper that does exactly that,
> taking the platform device and a struct pci_ecam_op as parameters.
> 
> This can then be called from the probe routine, and a lot of the
> code that isn't relevant to PCI setup moved away from the .init()
> callback. This also removes the dependency on the device match
> data, which is an oddity.
> 
> Reviewed-by: Rob Herring (Arm) <robh@xxxxxxxxxx>
> Acked-by: Alyssa Rosenzweig <alyssa@xxxxxxxxxxxxx>
> Tested-by: Janne Grunau <j@xxxxxxxxxx>
> Signed-off-by: Marc Zyngier <maz@xxxxxxxxxx>

Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@xxxxxxxxxx>

- Mani

> ---
>  drivers/pci/controller/pci-host-common.c | 24 ++++++++++++++++--------
>  include/linux/pci-ecam.h                 |  2 ++
>  2 files changed, 18 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/pci/controller/pci-host-common.c b/drivers/pci/controller/pci-host-common.c
> index f441bfd6f96a8..466a1e6a7ffcd 100644
> --- a/drivers/pci/controller/pci-host-common.c
> +++ b/drivers/pci/controller/pci-host-common.c
> @@ -49,23 +49,17 @@ static struct pci_config_window *gen_pci_init(struct device *dev,
>  	return cfg;
>  }
>  
> -int pci_host_common_probe(struct platform_device *pdev)
> +int pci_host_common_init(struct platform_device *pdev,
> +			 const struct pci_ecam_ops *ops)
>  {
>  	struct device *dev = &pdev->dev;
>  	struct pci_host_bridge *bridge;
>  	struct pci_config_window *cfg;
> -	const struct pci_ecam_ops *ops;
> -
> -	ops = of_device_get_match_data(&pdev->dev);
> -	if (!ops)
> -		return -ENODEV;
>  
>  	bridge = devm_pci_alloc_host_bridge(dev, 0);
>  	if (!bridge)
>  		return -ENOMEM;
>  
> -	platform_set_drvdata(pdev, bridge);
> -
>  	of_pci_check_probe_only();
>  
>  	/* Parse and map our Configuration Space windows */
> @@ -73,6 +67,8 @@ int pci_host_common_probe(struct platform_device *pdev)
>  	if (IS_ERR(cfg))
>  		return PTR_ERR(cfg);
>  
> +	platform_set_drvdata(pdev, bridge);
> +
>  	bridge->sysdata = cfg;
>  	bridge->ops = (struct pci_ops *)&ops->pci_ops;
>  	bridge->enable_device = ops->enable_device;
> @@ -81,6 +77,18 @@ int pci_host_common_probe(struct platform_device *pdev)
>  
>  	return pci_host_probe(bridge);
>  }
> +EXPORT_SYMBOL_GPL(pci_host_common_init);
> +
> +int pci_host_common_probe(struct platform_device *pdev)
> +{
> +	const struct pci_ecam_ops *ops;
> +
> +	ops = of_device_get_match_data(&pdev->dev);
> +	if (!ops)
> +		return -ENODEV;
> +
> +	return pci_host_common_init(pdev, ops);
> +}
>  EXPORT_SYMBOL_GPL(pci_host_common_probe);
>  
>  void pci_host_common_remove(struct platform_device *pdev)
> diff --git a/include/linux/pci-ecam.h b/include/linux/pci-ecam.h
> index 3a10f8cfc3ad5..bc2ca2c72ee23 100644
> --- a/include/linux/pci-ecam.h
> +++ b/include/linux/pci-ecam.h
> @@ -97,6 +97,8 @@ extern const struct pci_ecam_ops loongson_pci_ecam_ops; /* Loongson PCIe */
>  #if IS_ENABLED(CONFIG_PCI_HOST_COMMON)
>  /* for DT-based PCI controllers that support ECAM */
>  int pci_host_common_probe(struct platform_device *pdev);
> +int pci_host_common_init(struct platform_device *pdev,
> +			 const struct pci_ecam_ops *ops);
>  void pci_host_common_remove(struct platform_device *pdev);
>  #endif
>  #endif
> -- 
> 2.39.2
> 

-- 
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