Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1763660Ab3IEMuy (ORCPT ); Thu, 5 Sep 2013 08:50:54 -0400 Received: from mx1.redhat.com ([209.132.183.28]:11747 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1761785Ab3IEMuw (ORCPT ); Thu, 5 Sep 2013 08:50:52 -0400 Date: Thu, 5 Sep 2013 14:52:47 +0200 From: Alexander Gordeev To: linux-kernel@vger.kernel.org Cc: x86@kernel.org, linux-pci@vger.kernel.org, linux-ide@vger.kernel.org, Tejun Heo , Ingo Molnar , Joerg Roedel , Jan Beulich , Bjorn Helgaas Subject: [PATCH v2 2/6] PCI/MSI: Factor out pci_get_msi_cap() interface Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3746 Lines: 130 Factor out the operation of retrieving the number of MSI vectors the device requested, that is a value encoded in the Multiple Message Capable register. This change is a prerequisite for the forthcoming update of the AHCI device driver. Signed-off-by: Alexander Gordeev --- Documentation/PCI/MSI-HOWTO.txt | 12 ++++++++++++ drivers/pci/msi.c | 30 ++++++++++++++++++++---------- include/linux/pci.h | 6 ++++++ 3 files changed, 38 insertions(+), 10 deletions(-) diff --git a/Documentation/PCI/MSI-HOWTO.txt b/Documentation/PCI/MSI-HOWTO.txt index 32d7d15..205eb5d 100644 --- a/Documentation/PCI/MSI-HOWTO.txt +++ b/Documentation/PCI/MSI-HOWTO.txt @@ -209,6 +209,18 @@ on any interrupt for which it previously called request_irq(). Failure to do so results in a BUG_ON(), leaving the device with MSI enabled and thus leaking its vector. +4.2.6 pci_get_msi_cap + +int pci_get_msi_cap(struct pci_dev *dev) + +This function could be used to retrieve the number of MSI vectors the +device requested (via the Multiple Message Capable register). The MSI +specification only allows the returned value to be a power of two, +up to a maximum of 2^5 (32). + +If this function returns a negative number, it indicates the device is +not capable of sending MSIs. + 4.3 Using MSI-X The MSI-X capability is much more flexible than the MSI capability. diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c index 647e9b1..c50d518 100644 --- a/drivers/pci/msi.c +++ b/drivers/pci/msi.c @@ -802,17 +802,30 @@ static int pci_msi_check_device(struct pci_dev *dev, return 0; } -int pci_enable_msi_block_part(struct pci_dev *dev, - unsigned int nvec, int nvec_mme) +int pci_get_msi_cap(struct pci_dev *dev) { - int status, maxvec; + int ret; u16 msgctl; if (!dev->msi_cap) return -EINVAL; pci_read_config_word(dev, dev->msi_cap + PCI_MSI_FLAGS, &msgctl); - maxvec = 1 << ((msgctl & PCI_MSI_FLAGS_QMASK) >> 1); + ret = 1 << ((msgctl & PCI_MSI_FLAGS_QMASK) >> 1); + + return ret; +} +EXPORT_SYMBOL(pci_get_msi_cap); + +int pci_enable_msi_block_part(struct pci_dev *dev, + unsigned int nvec, int nvec_mme) +{ + int status, maxvec; + u16 msgctl; + + maxvec = pci_get_msi_cap(dev); + if (maxvec < 0) + return maxvec; if (nvec_mme < 0) nvec_mme = maxvec; @@ -869,13 +882,10 @@ EXPORT_SYMBOL(pci_enable_msi_block); int pci_enable_msi_block_auto(struct pci_dev *dev, unsigned int *maxvec) { int ret, nvec; - u16 msgctl; - - if (!dev->msi_cap) - return -EINVAL; - pci_read_config_word(dev, dev->msi_cap + PCI_MSI_FLAGS, &msgctl); - ret = 1 << ((msgctl & PCI_MSI_FLAGS_QMASK) >> 1); + ret = pci_get_msi_cap(dev); + if (ret < 0) + return ret; if (maxvec) *maxvec = ret; diff --git a/include/linux/pci.h b/include/linux/pci.h index 6552cee..b866048 100644 --- a/include/linux/pci.h +++ b/include/linux/pci.h @@ -1122,6 +1122,11 @@ struct msix_entry { #ifndef CONFIG_PCI_MSI +static inline int pci_get_msi_cap(struct pci_dev *dev) +{ + return -1; +} + static inline int pci_enable_msi_block_part(struct pci_dev *dev, unsigned int nvec, int nvec_mme) { @@ -1169,6 +1174,7 @@ static inline int pci_msi_enabled(void) return 0; } #else +int pci_get_msi_cap(struct pci_dev *dev); int pci_enable_msi_block_part(struct pci_dev *dev, unsigned int nvec, int nvec_mme); int pci_enable_msi_block(struct pci_dev *dev, unsigned int nvec); -- 1.7.7.6 -- Regards, Alexander Gordeev agordeev@redhat.com -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/