Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751279Ab3JSHDK (ORCPT ); Sat, 19 Oct 2013 03:03:10 -0400 Received: from 221-186-24-89.in-addr.arpa ([89.24.186.221]:14960 "EHLO dhcp-26-207.brq.redhat.com" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1750948Ab3JSHDI (ORCPT ); Sat, 19 Oct 2013 03:03:08 -0400 From: Alexander Gordeev To: linux-kernel@vger.kernel.org Cc: Alexander Gordeev , Bjorn Helgaas , Michael Ellerman , Benjamin Herrenschmidt , Tejun Heo , Ben Hutchings , David Laight , Mark Lord , "H. Peter Anvin" , linux-pci@vger.kernel.org Subject: [PATCH RFC v2 09/29] PCI/MSI: Factor out pci_get_msi_cap() interface Date: Fri, 18 Oct 2013 19:12:09 +0200 Message-Id: <85500e7239fcb104df091bbfa873eef8ae654772.1382103786.git.agordeev@redhat.com> X-Mailer: git-send-email 1.7.7.6 In-Reply-To: References: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3983 Lines: 129 Device drivers can use this interface to obtain maximum number of MSI interrupts the device supports and use that number i.e. in a following call to pci_enable_msi_block() interface. Signed-off-by: Alexander Gordeev --- Documentation/PCI/MSI-HOWTO.txt | 15 +++++++++++++++ drivers/pci/msi.c | 33 +++++++++++++++++++++------------ include/linux/pci.h | 6 ++++++ 3 files changed, 42 insertions(+), 12 deletions(-) diff --git a/Documentation/PCI/MSI-HOWTO.txt b/Documentation/PCI/MSI-HOWTO.txt index 845edb5..e7e3b20 100644 --- a/Documentation/PCI/MSI-HOWTO.txt +++ b/Documentation/PCI/MSI-HOWTO.txt @@ -169,6 +169,21 @@ 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. +4.2.5 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. + +If this function returns a positive number, it indicates the maximum +number of MSI interrupt vectors that could be allocated. + 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 fdae3a4..14dc4d1 100644 --- a/drivers/pci/msi.c +++ b/drivers/pci/msi.c @@ -795,6 +795,21 @@ static int pci_msi_check_device(struct pci_dev *dev, int nvec, int type) return 0; } +int pci_get_msi_cap(struct pci_dev *dev) +{ + int ret; + 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); + + return ret; +} +EXPORT_SYMBOL(pci_get_msi_cap); + /** * pci_enable_msi_block - configure device's MSI capability structure * @dev: device to configure @@ -811,13 +826,10 @@ static int pci_msi_check_device(struct pci_dev *dev, int nvec, int type) int pci_enable_msi_block(struct pci_dev *dev, unsigned int nvec) { int status, maxvec; - 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); + maxvec = pci_get_msi_cap(dev); + if (maxvec < 0) + return maxvec; if (nvec > maxvec) return maxvec; @@ -842,13 +854,10 @@ 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 d6832de..df72084 100644 --- a/include/linux/pci.h +++ b/include/linux/pci.h @@ -1146,6 +1146,11 @@ struct msix_entry { #ifndef CONFIG_PCI_MSI +static inline int pci_get_msi_cap(struct pci_dev *dev) +{ + return -ENOSYS; +} + static inline int pci_enable_msi_block(struct pci_dev *dev, unsigned int nvec) { return -ENOSYS; @@ -1187,6 +1192,7 @@ static inline int pci_msi_enabled(void) return 0; } #else +int pci_get_msi_cap(struct pci_dev *dev); int pci_enable_msi_block(struct pci_dev *dev, unsigned int nvec); int pci_enable_msi_block_auto(struct pci_dev *dev, unsigned int *maxvec); void pci_msi_shutdown(struct pci_dev *dev); -- 1.7.7.6 -- 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/