linux-kernel - Re: [PATCH v4 05/12] PCI: endpoint: Assign PCI domain number for endpoint controllers

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Message-ID: <Zs9stQDfpUcpIxt9@lizhi-Precision-Tower-5810>
Date: Wed, 28 Aug 2024 14:30:13 -0400
From: Frank Li <Frank.li@....com>
To: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
Cc: Lorenzo Pieralisi <lpieralisi@...nel.org>,
	Krzysztof Wilczyński <kw@...ux.com>,
	Rob Herring <robh@...nel.org>, Bjorn Helgaas <bhelgaas@...gle.com>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>,
	Kishon Vijay Abraham I <kishon@...nel.org>,
	Bjorn Andersson <andersson@...nel.org>,
	Konrad Dybcio <konradybcio@...nel.org>, linux-pci@...r.kernel.org,
	linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org,
	devicetree@...r.kernel.org
Subject: Re: [PATCH v4 05/12] PCI: endpoint: Assign PCI domain number for
 endpoint controllers

On Wed, Aug 28, 2024 at 09:16:15PM +0530, Manivannan Sadhasivam wrote:
> Right now, PCI endpoint subsystem doesn't assign PCI domain number for the
> PCI endpoint controllers. But this domain number could be useful to the EPC
> drivers to uniquely identify each controller based on the hardware instance
> when there are multiple ones present in an SoC (even multiple RC/EP).
>
> So let's make use of the existing pci_bus_find_domain_nr() API to allocate
> domain numbers based on either Devicetree (linux,pci-domain) property or
> dynamic domain number allocation scheme.
>
> It should be noted that the domain number allocated by this API will be
> based on both RC and EP controllers in a SoC. If the 'linux,pci-domain' DT
> property is present, then the domain number represents the actual hardware
> instance of the PCI endpoint controller. If not, then the domain number
> will be allocated based on the PCI EP/RC controller probe order.
>
> If the architecture doesn't support CONFIG_PCI_DOMAINS_GENERIC (rare), then
> currently a warning is thrown to indicate that the architecture specific
> implementation is needed.
>

Reviewed-by: Frank Li <Frank.Li@....com>

> Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
> ---
>  drivers/pci/endpoint/pci-epc-core.c | 14 ++++++++++++++
>  include/linux/pci-epc.h             |  2 ++
>  2 files changed, 16 insertions(+)
>
> diff --git a/drivers/pci/endpoint/pci-epc-core.c b/drivers/pci/endpoint/pci-epc-core.c
> index 84309dfe0c68..085a2de8b923 100644
> --- a/drivers/pci/endpoint/pci-epc-core.c
> +++ b/drivers/pci/endpoint/pci-epc-core.c
> @@ -838,6 +838,10 @@ void pci_epc_destroy(struct pci_epc *epc)
>  {
>  	pci_ep_cfs_remove_epc_group(epc->group);
>  	device_unregister(&epc->dev);
> +
> +#ifdef CONFIG_PCI_DOMAINS_GENERIC
> +	pci_bus_release_domain_nr(NULL, &epc->dev);
> +#endif
>  }
>  EXPORT_SYMBOL_GPL(pci_epc_destroy);
>
> @@ -900,6 +904,16 @@ __pci_epc_create(struct device *dev, const struct pci_epc_ops *ops,
>  	epc->dev.release = pci_epc_release;
>  	epc->ops = ops;
>
> +#ifdef CONFIG_PCI_DOMAINS_GENERIC
> +	epc->domain_nr = pci_bus_find_domain_nr(NULL, dev);
> +#else
> +	/*
> +	 * TODO: If the architecture doesn't support generic PCI
> +	 * domains, then a custom implementation has to be used.
> +	 */
> +	WARN_ONCE(1, "This architecture doesn't support generic PCI domains\n");
> +#endif
> +
>  	ret = dev_set_name(&epc->dev, "%s", dev_name(dev));
>  	if (ret)
>  		goto put_dev;
> diff --git a/include/linux/pci-epc.h b/include/linux/pci-epc.h
> index 85bdf2adb760..8e3dcac55dcd 100644
> --- a/include/linux/pci-epc.h
> +++ b/include/linux/pci-epc.h
> @@ -128,6 +128,7 @@ struct pci_epc_mem {
>   * @group: configfs group representing the PCI EPC device
>   * @lock: mutex to protect pci_epc ops
>   * @function_num_map: bitmap to manage physical function number
> + * @domain_nr: PCI domain number of the endpoint controller
>   * @init_complete: flag to indicate whether the EPC initialization is complete
>   *                 or not
>   */
> @@ -145,6 +146,7 @@ struct pci_epc {
>  	/* mutex to protect against concurrent access of EP controller */
>  	struct mutex			lock;
>  	unsigned long			function_num_map;
> +	int				domain_nr;
>  	bool				init_complete;
>  };
>
>
> --
> 2.25.1
>