On Wed, Apr 26, 2017 at 1:17 PM, Lorenzo Pieralisi
<lorenzo.pieralisi@xxxxxxx> wrote:
> Current pci_scan_root_bus() interface is made up of two main
> code paths:
>
> - pci_create_root_bus()
> - pci_scan_child_bus()
>
> pci_create_root_bus() is a wrapper function that allows to create
> a struct pci_host_bridge structure, initialize it with the passed
> parameters and register it with the kernel.
>
> As the struct pci_host_bridge require additional struct members,
> pci_create_root_bus() parameters list has grown in time, making
> it unwieldy to add further parameters to it in case the struct
> pci_host_bridge gains more members fields to augment its functionality.
>
> Since PCI core code provides functions to allocate struct
> pci_host_bridge, instead of forcing the pci_create_root_bus() interface
> to add new parameters to cater for new struct pci_host_bridge
> functionality, it is more suitable to add an interface in PCI
> core code to scan a PCI bus straight from a struct pci_host_bridge
> created and customized by each specific PCI host controller driver.
>
> Add a pci_scan_root_bus_bridge() function to allow PCI host controller
> drivers to create and initialize struct pci_host_bridge and scan
> the resulting bus.
>
> Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@xxxxxxx>
> Cc: Arnd Bergmann <arnd@xxxxxxxx>
> Cc: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
Good idea, yes. To avoid growing the number of interfaces too
much, should we change the existing users of pci_register_host_bridge
in host drivers over to this entry point, and make the other one
local to probe.c then?
> diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
> index 7e4ffc4..c7a7f72 100644
> --- a/drivers/pci/probe.c
> +++ b/drivers/pci/probe.c
> @@ -2412,6 +2412,44 @@ void pci_bus_release_busn_res(struct pci_bus *b)
> res, ret ? "can not be" : "is");
> }
>
> +int pci_scan_root_bus_bridge(struct pci_host_bridge *bridge)
> +{
> + struct resource_entry *window;
> + bool found = false;
> + struct pci_bus *b;
> + int max, bus, ret;
> +
> + if (!bridge)
> + return -EINVAL;
> +
> + resource_list_for_each_entry(window, &bridge->windows)
> + if (window->res->flags & IORESOURCE_BUS) {
> + found = true;
> + break;
> + }
> +
> + ret = pci_register_host_bridge(bridge);
> + if (ret < 0)
> + return ret;
> +
> + b = bridge->bus;
> + bus = bridge->busnr;
> +
> + if (!found) {
> + dev_info(&b->dev,
> + "No busn resource found for root bus, will use [bus %02x-ff]\n",
> + bus);
> + pci_bus_insert_busn_res(b, bus, 255);
> + }
> +
> + max = pci_scan_child_bus(b);
> +
> + if (!found)
> + pci_bus_update_busn_res_end(b, max);
> +
> + return 0;
> +}
> +
We probably want an EXPORT_SYMBOL() here as well.
Arnd
