From mboxrd@z Thu Jan 1 00:00:00 1970 From: Bjorn Helgaas Subject: Re: [PATCH 05/12] PCI: add pci_swizzle_interrupt_pin() Date: Thu, 11 Dec 2008 11:24:23 -0700 Message-ID: <200812111124.25026.bjorn.helgaas@hp.com> References: <200812111103.10500.bjorn.helgaas@hp.com> <24742.1229016892@redhat.com> <25771.1229019295@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-15" Content-Transfer-Encoding: 7bit Return-path: Received: from g4t0015.houston.hp.com ([15.201.24.18]:14011 "EHLO g4t0015.houston.hp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754247AbYLKSY3 (ORCPT ); Thu, 11 Dec 2008 13:24:29 -0500 In-Reply-To: <25771.1229019295@redhat.com> Content-Disposition: inline Sender: linux-arch-owner@vger.kernel.org List-ID: To: David Howells Cc: Jesse Barnes , linux-pci@vger.kernel.org, linux-arch@vger.kernel.org, Ivan Kokshaysky , Russell King , Ralf Baechle , Kyle McMartin , Matthew Wilcox , Grant Grundler , Paul Mackerras , Benjamin Herrenschmidt , Paul Mundt , Thomas Gleixner , Ingo Molnar , hpa@zytor.com On Thursday 11 December 2008 11:14:55 am David Howells wrote: > Bjorn Helgaas wrote: > > > +/** > > + * pci_swizzle_interrupt_pin - swizzle INTx for device behind bridge > > + * @dev: the PCI device > > + * @pin: the INTx pin (1=INTA, 2=INTB, 3=INTD, 4=INTD) > > + * > > + * The PCI-to-PCI bridge specification, section 9.1, requires INTx swizzling > > + * for devices behind bridges on add-in cards. This performs the swizzle > > + * for one level of bridge. > > + */ > > That's okay. It might be better to put the what before the why, though: > > * Perform INTx swizzling for a device behind one level of bridge. This is > * required by section 9.1 of the PCI-to-PCI bridge specification for devices > * behind bridges on add-in cards. That *is* much better. Thanks for the wordsmithing. PCI: add pci_swizzle_interrupt_pin() From: Bjorn Helgaas This patch adds pci_swizzle_interrupt_pin(), which implements the INTx swizzling algorithm specified in Table 9-1 of the "PCI-to-PCI Bridge Architecture Specification," revision 1.2. There are many architecture-specific implementations of this swizzle that can be replaced by this common one. Signed-off-by: Bjorn Helgaas --- drivers/pci/pci.c | 16 +++++++++++++++- include/linux/pci.h | 1 + 2 files changed, 16 insertions(+), 1 deletions(-) diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c index 46f6821..388a32a 100644 --- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c @@ -1337,6 +1337,20 @@ void pci_enable_ari(struct pci_dev *dev) bridge->ari_enabled = 1; } +/** + * pci_swizzle_interrupt_pin - swizzle INTx for device behind bridge + * @dev: the PCI device + * @pin: the INTx pin (1=INTA, 2=INTB, 3=INTD, 4=INTD) + * + * Perform INTx swizzling for a device behind one level of bridge. This is + * required by section 9.1 of the PCI-to-PCI bridge specification for devices + * behind bridges on add-in cards. + */ +u8 pci_swizzle_interrupt_pin(struct pci_dev *dev, u8 pin) +{ + return (((pin - 1) + PCI_SLOT(dev->devfn)) % 4) + 1; +} + int pci_get_interrupt_pin(struct pci_dev *dev, struct pci_dev **bridge) { @@ -1347,7 +1361,7 @@ pci_get_interrupt_pin(struct pci_dev *dev, struct pci_dev **bridge) return -1; while (dev->bus->self) { - pin = (((pin - 1) + PCI_SLOT(dev->devfn)) % 4) + 1; + pin = pci_swizzle_interrupt_pin(dev, pin); dev = dev->bus->self; } *bridge = dev; diff --git a/include/linux/pci.h b/include/linux/pci.h index feb4657..4be596f 100644 --- a/include/linux/pci.h +++ b/include/linux/pci.h @@ -527,6 +527,7 @@ int __must_check pci_bus_add_device(struct pci_dev *dev); void pci_read_bridge_bases(struct pci_bus *child); struct resource *pci_find_parent_resource(const struct pci_dev *dev, struct resource *res); +u8 pci_swizzle_interrupt_pin(struct pci_dev *dev, u8 pin); int pci_get_interrupt_pin(struct pci_dev *dev, struct pci_dev **bridge); extern struct pci_dev *pci_dev_get(struct pci_dev *dev); extern void pci_dev_put(struct pci_dev *dev);