From patchwork Mon Dec 30 07:28:13 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alexander Gordeev X-Patchwork-Id: 3417821 X-Patchwork-Delegate: bhelgaas@google.com Return-Path: X-Original-To: patchwork-linux-pci@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork2.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.19.201]) by patchwork2.web.kernel.org (Postfix) with ESMTP id 26A68C02DC for ; Mon, 30 Dec 2013 07:28:16 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 580F2200FE for ; Mon, 30 Dec 2013 07:28:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 64ECC200CF for ; Mon, 30 Dec 2013 07:28:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751375Ab3L3H1C (ORCPT ); Mon, 30 Dec 2013 02:27:02 -0500 Received: from 221-186-24-89.in-addr.arpa ([89.24.186.221]:14216 "EHLO dhcp-26-207.brq.redhat.com" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1751346Ab3L3H1A (ORCPT ); Mon, 30 Dec 2013 02:27:00 -0500 Received: from dhcp-26-207.brq.redhat.com (localhost [127.0.0.1]) by dhcp-26-207.brq.redhat.com (8.14.5/8.14.5) with ESMTP id rBU7Sa8p032237; Mon, 30 Dec 2013 08:28:36 +0100 Received: (from agordeev@localhost) by dhcp-26-207.brq.redhat.com (8.14.5/8.14.5/Submit) id rBU7SXR6032236; Mon, 30 Dec 2013 08:28:33 +0100 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 v5 1/4] PCI/MSI: Factor out pci_msi_vec_count() interface Date: Mon, 30 Dec 2013 08:28:13 +0100 Message-Id: <4f6330995d90c654b045d5457ea90b0c633e07a6.1388262668.git.agordeev@redhat.com> X-Mailer: git-send-email 1.7.7.6 In-Reply-To: References: Sender: linux-pci-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org X-Spam-Status: No, score=-7.0 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP 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 Reviewed-by: Tejun Heo --- Documentation/PCI/MSI-HOWTO.txt | 15 ++++++++++++++ drivers/pci/msi.c | 41 +++++++++++++++++++++++++++++++------- include/linux/pci.h | 6 +++++ 3 files changed, 54 insertions(+), 8 deletions(-) diff --git a/Documentation/PCI/MSI-HOWTO.txt b/Documentation/PCI/MSI-HOWTO.txt index a4d174e..a8b4178 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_msi_vec_count + +int pci_msi_vec_count(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 22957aa..5233e28 100644 --- a/drivers/pci/msi.c +++ b/drivers/pci/msi.c @@ -852,6 +852,31 @@ static int pci_msi_check_device(struct pci_dev *dev, int nvec, int type) } /** + * pci_msi_vec_count - Return the number of MSI vectors a device can send + * @dev: device to report about + * + * This function returns the number of MSI vectors a device requested via + * Multiple Message Capable register. It returns a negative errno if the + * device is not capable sending MSI interrupts. Otherwise, the call succeeds + * and returns a power of two, up to a maximum of 2^5 (32), according to the + * MSI specification. + **/ +int pci_msi_vec_count(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_msi_vec_count); + +/** * pci_enable_msi_block - configure device's MSI capability structure * @dev: device to configure * @nvec: number of interrupts to configure @@ -867,13 +892,13 @@ static int pci_msi_check_device(struct pci_dev *dev, int nvec, int type) int pci_enable_msi_block(struct pci_dev *dev, int nvec) { int status, maxvec; - u16 msgctl; - if (!dev->msi_cap || dev->current_state != PCI_D0) + if (dev->current_state != PCI_D0) return -EINVAL; - pci_read_config_word(dev, dev->msi_cap + PCI_MSI_FLAGS, &msgctl); - maxvec = 1 << ((msgctl & PCI_MSI_FLAGS_QMASK) >> 1); + maxvec = pci_msi_vec_count(dev); + if (maxvec < 0) + return maxvec; if (nvec > maxvec) return maxvec; @@ -898,13 +923,13 @@ EXPORT_SYMBOL(pci_enable_msi_block); int pci_enable_msi_block_auto(struct pci_dev *dev, int *maxvec) { int ret, nvec; - u16 msgctl; - if (!dev->msi_cap || dev->current_state != PCI_D0) + if (dev->current_state != PCI_D0) return -EINVAL; - pci_read_config_word(dev, dev->msi_cap + PCI_MSI_FLAGS, &msgctl); - ret = 1 << ((msgctl & PCI_MSI_FLAGS_QMASK) >> 1); + ret = pci_msi_vec_count(dev); + if (ret < 0) + return ret; if (maxvec) *maxvec = ret; diff --git a/include/linux/pci.h b/include/linux/pci.h index 4b7cf4c..0322af1 100644 --- a/include/linux/pci.h +++ b/include/linux/pci.h @@ -1166,6 +1166,11 @@ struct msix_entry { #ifndef CONFIG_PCI_MSI +static inline int pci_msi_vec_count(struct pci_dev *dev) +{ + return -ENOSYS; +} + static inline int pci_enable_msi_block(struct pci_dev *dev, int nvec) { return -ENOSYS; @@ -1207,6 +1212,7 @@ static inline int pci_msi_enabled(void) return 0; } #else +int pci_msi_vec_count(struct pci_dev *dev); int pci_enable_msi_block(struct pci_dev *dev, int nvec); int pci_enable_msi_block_auto(struct pci_dev *dev, int *maxvec); void pci_msi_shutdown(struct pci_dev *dev);