Re: [PATCH v2 3/9] PCI: Add generic function to probe PCI host controllers

[Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>]

On Mon, Dec 18, 2017 at 07:16:03PM +0100, Cyrille Pitchen wrote:
> This patchs moves generic source code from
> drivers/pci/host/pci-host-common.c into drivers/pci/probe.c.
> 
> Indeed the extracted lines of code were duplicated by many host
> controller drivers. Regrouping them into a generic function gives a
> change to properly share this code without introducing a useless
> dependency to PCI_HOST_COMMON, which selects PCI_ECAM when not needed by
> most host controller drivers.
> 
> Signed-off-by: Cyrille Pitchen <cyrille.pitchen@free-electrons.com>
> ---
>  drivers/pci/host/pci-host-common.c | 38 +++--------------------------
>  drivers/pci/probe.c                | 50 ++++++++++++++++++++++++++++++++++++++
>  include/linux/pci.h                |  3 +++
>  3 files changed, 57 insertions(+), 34 deletions(-)
> 
> diff --git a/drivers/pci/host/pci-host-common.c b/drivers/pci/host/pci-host-common.c
> index a613ea310e76..ba5d3dab5d89 100644
> --- a/drivers/pci/host/pci-host-common.c
> +++ b/drivers/pci/host/pci-host-common.c
> @@ -72,7 +72,6 @@ int pci_host_common_probe(struct platform_device *pdev,
>  	const char *type;
>  	struct device *dev = &pdev->dev;
>  	struct device_node *np = dev->of_node;
> -	struct pci_bus *bus, *child;
>  	struct pci_host_bridge *bridge;
>  	struct pci_config_window *cfg;
>  	struct list_head resources;
> @@ -95,41 +94,12 @@ int pci_host_common_probe(struct platform_device *pdev,
>  	if (IS_ERR(cfg))
>  		return PTR_ERR(cfg);
>  
> -	/* Do not reassign resources if probe only */
> -	if (!pci_has_flag(PCI_PROBE_ONLY))
> -		pci_add_flags(PCI_REASSIGN_ALL_BUS);
> -
> -	list_splice_init(&resources, &bridge->windows);
> -	bridge->dev.parent = dev;
> -	bridge->sysdata = cfg;
> -	bridge->busnr = cfg->busr.start;
> -	bridge->ops = &ops->pci_ops;
> -	bridge->map_irq = of_irq_parse_and_map_pci;
> -	bridge->swizzle_irq = pci_common_swizzle;

Hi Cyrille,

I appreciate the idea, I think though that the setting of
PCI_REASSIGN_ALL_BUS and the bridge hooks/members initialization should
be left to the host bridges probe routines, that was the reasoning
behind adding those hooks to struct pci_host_bridge in the first place.

You can create an OF wrapper that does call the resulting function (eg
of_pci_host_common_probe()) that sets the {map/swizzle}_irq() to the OF
version and then call pci_host_common_probe().

Lorenzo

> -
> -	ret = pci_scan_root_bus_bridge(bridge);
> -	if (ret < 0) {
> -		dev_err(dev, "Scanning root bridge failed");
> +	ret = pci_host_probe(bridge, dev, cfg->busr.start, &ops->pci_ops, cfg,
> +			     &resources);
> +	if (ret) {
> +		pci_free_resource_list(&resources);
>  		return ret;
>  	}
>  
> -	bus = bridge->bus;
> -
> -	/*
> -	 * We insert PCI resources into the iomem_resource and
> -	 * ioport_resource trees in either pci_bus_claim_resources()
> -	 * or pci_bus_assign_resources().
> -	 */
> -	if (pci_has_flag(PCI_PROBE_ONLY)) {
> -		pci_bus_claim_resources(bus);
> -	} else {
> -		pci_bus_size_bridges(bus);
> -		pci_bus_assign_resources(bus);
> -
> -		list_for_each_entry(child, &bus->children, node)
> -			pcie_bus_configure_settings(child);
> -	}
> -
> -	pci_bus_add_devices(bus);
>  	return 0;
>  }
> diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
> index 1360db508035..3dfdc579b7de 100644
> --- a/drivers/pci/probe.c
> +++ b/drivers/pci/probe.c
> @@ -2685,6 +2685,56 @@ struct pci_bus *pci_create_root_bus(struct device *parent, int bus,
>  }
>  EXPORT_SYMBOL_GPL(pci_create_root_bus);
>  
> +int pci_host_probe(struct pci_host_bridge *bridge,
> +		   struct device *parent,
> +		   int busnr,
> +		   struct pci_ops *ops,
> +		   void *sysdata,
> +		   struct list_head *resources)
> +{
> +	struct pci_bus *bus, *child;
> +	int ret;
> +
> +	/* Do not reassign resources if probe only */
> +	if (!pci_has_flag(PCI_PROBE_ONLY))
> +		pci_add_flags(PCI_REASSIGN_ALL_BUS);
> +
> +	list_splice_init(resources, &bridge->windows);
> +	bridge->dev.parent = parent;
> +	bridge->sysdata = sysdata;
> +	bridge->busnr = busnr;
> +	bridge->ops = ops;
> +	bridge->map_irq = of_irq_parse_and_map_pci;
> +	bridge->swizzle_irq = pci_common_swizzle;
> +
> +	ret = pci_scan_root_bus_bridge(bridge);
> +	if (ret < 0) {
> +		dev_err(parent, "Scanning root bridge failed");
> +		return ret;
> +	}
> +
> +	bus = bridge->bus;
> +
> +	/*
> +	 * We insert PCI resources into the iomem_resource and
> +	 * ioport_resource trees in either pci_bus_claim_resources()
> +	 * or pci_bus_assign_resources().
> +	 */
> +	if (pci_has_flag(PCI_PROBE_ONLY)) {
> +		pci_bus_claim_resources(bus);
> +	} else {
> +		pci_bus_size_bridges(bus);
> +		pci_bus_assign_resources(bus);
> +
> +		list_for_each_entry(child, &bus->children, node)
> +			pcie_bus_configure_settings(child);
> +	}
> +
> +	pci_bus_add_devices(bus);
> +	return 0;
> +}
> +EXPORT_SYMBOL_GPL(pci_host_probe);
> +
>  int pci_bus_insert_busn_res(struct pci_bus *b, int bus, int bus_max)
>  {
>  	struct resource *res = &b->busn_res;
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index 11823f4f1d83..e76df07dac07 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -879,6 +879,9 @@ struct pci_bus *pci_scan_bus(int bus, struct pci_ops *ops, void *sysdata);
>  struct pci_bus *pci_create_root_bus(struct device *parent, int bus,
>  				    struct pci_ops *ops, void *sysdata,
>  				    struct list_head *resources);
> +int pci_host_probe(struct pci_host_bridge *bridge, struct device *parent,
> +		   int busnr, struct pci_ops *ops, void *sysdata,
> +		   struct list_head *resources);
>  int pci_bus_insert_busn_res(struct pci_bus *b, int bus, int busmax);
>  int pci_bus_update_busn_res_end(struct pci_bus *b, int busmax);
>  void pci_bus_release_busn_res(struct pci_bus *b);
> -- 
> 2.11.0
>