On Tue, Jan 13, 2015 at 08:57:27PM +0100, Lucas Stach wrote:
> This adds a simple way to get the root port a given device
> is connected to.
>
> Signed-off-by: Lucas Stach <[email protected]>
> ---
> v2: new patch in v2
> v3: rename to pci_find_rootport to fit better with other API
> ---
> drivers/pci/search.c | 20 ++++++++++++++++++++
> include/linux/pci.h | 1 +
> 2 files changed, 21 insertions(+)
>
> diff --git a/drivers/pci/search.c b/drivers/pci/search.c
> index a20ce7d5e2a7..7254f126096d 100644
> --- a/drivers/pci/search.c
> +++ b/drivers/pci/search.c
> @@ -384,3 +384,23 @@ int pci_dev_present(const struct pci_device_id *ids)
> return 0;
> }
> EXPORT_SYMBOL(pci_dev_present);
> +
> +/**
> + * pci_find_root_port - Returns the root port the given device is connected
> to.
> + * @dev: PCI device for which the root port should be found.
> + */
> +struct pci_dev *pci_find_root_port(struct pci_dev *dev)
This seems a little too generic. There are still PCI (non-PCIe) systems,
and on those this will return some non-Root Port device, the meaning of
which is unclear. I'm happy to put something like this in pci-tegra.c, but
until there are other potential users and we sort out the PCI/PCIe-ness of
the interface, I don't really want to make it global and exported.
> +{
> + struct pci_bus *bus = dev->bus;
> +
> + /* If there is no bridge on the bus the passed device is a root port. */
This assumption is false -- see the comment at pci_is_root_bus().
> + if (!bus->self)
> + return dev;
> +
> + /* Walk up the PCI hierarchy to the first level below the root. */
> + while (bus->parent && bus->parent->self)
> + bus = bus->parent;
> +
> + return bus->self;
> +}
> +EXPORT_SYMBOL(pci_find_root_port);
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index 360a966a97a5..f4321c5ba653 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -844,6 +844,7 @@ static inline struct pci_dev
> *pci_get_bus_and_slot(unsigned int bus,
> }
> struct pci_dev *pci_get_class(unsigned int class, struct pci_dev *from);
> int pci_dev_present(const struct pci_device_id *ids);
> +struct pci_dev *pci_find_root_port(struct pci_dev *dev);
>
> int pci_bus_read_config_byte(struct pci_bus *bus, unsigned int devfn,
> int where, u8 *val);
> --
> 2.1.4
>
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