From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from hqemgate14.nvidia.com ([216.228.121.143]:7847 "EHLO hqemgate14.nvidia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751005AbbIORLh (ORCPT ); Tue, 15 Sep 2015 13:11:37 -0400 From: Will Davis To: Bjorn Helgaas CC: Alex Williamson , Joerg Roedel , , , Konrad Wilk , Mark Hounschell , "David S. Miller" , Jonathan Corbet , Terence Ripperda , John Hubbard , Jerome Glisse , Will Davis Subject: [PATCH 08/22] PCI: Add pci_find_common_upstream_dev() Date: Tue, 15 Sep 2015 12:10:53 -0500 Message-ID: <1442337067-22964-9-git-send-email-wdavis@nvidia.com> In-Reply-To: <1442337067-22964-1-git-send-email-wdavis@nvidia.com> References: <1442337067-22964-1-git-send-email-wdavis@nvidia.com> MIME-Version: 1.0 Content-Type: text/plain Sender: linux-pci-owner@vger.kernel.org List-ID: Add an interface to find the first device which is upstream of both devices. Signed-off-by: Will Davis --- drivers/pci/search.c | 25 +++++++++++++++++++++++++ include/linux/pci.h | 2 ++ 2 files changed, 27 insertions(+) diff --git a/drivers/pci/search.c b/drivers/pci/search.c index a20ce7d..b6ed554 100644 --- a/drivers/pci/search.c +++ b/drivers/pci/search.c @@ -384,3 +384,28 @@ int pci_dev_present(const struct pci_device_id *ids) return 0; } EXPORT_SYMBOL(pci_dev_present); + +/** + * pci_find_common_upstream_dev - Returns the first common upstream device + * @dev: the PCI device from which the bus hierarchy walk will start + * @other: the PCI device whose bus number will be used for the search + * + * Walks up the bus hierarchy from the @dev device, looking for the first bus + * which the @other device is downstream of. Returns %NULL if the devices do + * not share any upstream devices. + */ +struct pci_dev *pci_find_common_upstream_dev(struct pci_dev *dev, + struct pci_dev *other) +{ + struct pci_dev *pdev = dev; + + while (pdev != NULL) { + if ((other->bus->number >= pdev->bus->busn_res.start) && + (other->bus->number <= pdev->bus->busn_res.end)) + return pdev; + pdev = pci_upstream_bridge(pdev); + } + + return NULL; +} +EXPORT_SYMBOL(pci_find_common_upstream_dev); diff --git a/include/linux/pci.h b/include/linux/pci.h index d58063e..8262b9e 100644 --- a/include/linux/pci.h +++ b/include/linux/pci.h @@ -860,6 +860,8 @@ 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_common_upstream_dev(struct pci_dev *from, + struct pci_dev *to); int pci_bus_read_config_byte(struct pci_bus *bus, unsigned int devfn, int where, u8 *val); -- 2.5.1