From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755266AbbFSWVu (ORCPT ); Fri, 19 Jun 2015 18:21:50 -0400 Received: from mail-pa0-f47.google.com ([209.85.220.47]:36734 "EHLO mail-pa0-f47.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751809AbbFSWVm (ORCPT ); Fri, 19 Jun 2015 18:21:42 -0400 From: "Luis R. Rodriguez" To: arnd@arndb.de Cc: linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, xen-devel@lists.xensource.com, linux-fbdev@vger.kernel.org, "Luis R. Rodriguez" , Toshi Kani , Andy Lutomirski , Suresh Siddha , Ingo Molnar , Thomas Gleixner , Juergen Gross , Daniel Vetter , Dave Airlie , Bjorn Helgaas , Antonino Daplas , Jean-Christophe Plagniol-Villard , Tomi Valkeinen , Dave Hansen , "Michael S. Tsirkin" , venkatesh.pallipadi@intel.com, Stefan Bader , =?UTF-8?q?Ville=20Syrj=C3=A4l=C3=A4?= , Mel Gorman , Vlastimil Babka , Borislav Petkov , Davidlohr Bueso , konrad.wilk@oracle.com, ville.syrjala@linux.intel.com, david.vrabel@citrix.com, jbeulich@suse.com, =?UTF-8?q?Roger=20Pau=20Monn=C3=A9?= Subject: [PATCH v7 5/9] PCI: Add pci_iomap_wc() variants Date: Fri, 19 Jun 2015 15:08:28 -0700 Message-Id: <1434751712-24333-6-git-send-email-mcgrof@do-not-panic.com> X-Mailer: git-send-email 2.1.4 In-Reply-To: <1434751712-24333-1-git-send-email-mcgrof@do-not-panic.com> References: <1434751712-24333-1-git-send-email-mcgrof@do-not-panic.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: "Luis R. Rodriguez" PCI BARs tell us whether prefetching is safe, but they don't say anything about write combining (WC). WC changes ordering rules and allows writes to be collapsed, so it's not safe in general to use it on a prefetchable region. Add pci_iomap_wc() and pci_iomap_wc_range() so drivers can take advantage of write combining when they know it's safe. On architectures that don't fully support WC, e.g., x86 without PAT, drivers for legacy framebuffers may get some of the benefit by using arch_phys_wc_add() in addition to pci_iomap_wc(). But arch_phys_wc_add() is unreliable and should be avoided in general. On x86, it uses MTRRs, which are limited in number and size, so the results will vary based on driver loading order. The goals of adding pci_iomap_wc() are to: - Give drivers an architecture-independent way to use WC so they can stop using interfaces like mtrr_add() (on x86, pci_iomap_wc() uses PAT when available) - Move toward using _PAGE_CACHE_MODE_UC, not _PAGE_CACHE_MODE_UC_MINUS, on x86 on ioremap_nocache() (see de33c442ed2a ("x86 PAT: fix performance drop for glx, use UC minus for ioremap(), ioremap_nocache() and pci_mmap_page_range()") Link: http://lkml.kernel.org/r/1426893517-2511-6-git-send-email-mcgrof@do-not-panic.com Original-posting: http://lkml.kernel.org/r/1432163293-20965-1-git-send-email-mcgrof@do-not-panic.com Cc: Toshi Kani Cc: Andy Lutomirski Cc: Suresh Siddha Cc: Ingo Molnar Cc: Thomas Gleixner Cc: Juergen Gross Cc: Daniel Vetter Cc: Dave Airlie Cc: Bjorn Helgaas Cc: Antonino Daplas Cc: Jean-Christophe Plagniol-Villard Cc: Tomi Valkeinen Cc: Dave Hansen Cc: Arnd Bergmann Cc: Michael S. Tsirkin Cc: venkatesh.pallipadi@intel.com Cc: Stefan Bader Cc: Ville Syrjälä Cc: Mel Gorman Cc: Vlastimil Babka Cc: Borislav Petkov Cc: Davidlohr Bueso Cc: konrad.wilk@oracle.com Cc: ville.syrjala@linux.intel.com Cc: david.vrabel@citrix.com Cc: jbeulich@suse.com Cc: Roger Pau Monné Cc: linux-fbdev@vger.kernel.org Cc: linux-kernel@vger.kernel.org Cc: xen-devel@lists.xensource.com Signed-off-by: Luis R. Rodriguez --- include/asm-generic/pci_iomap.h | 14 ++++++++++ lib/pci_iomap.c | 61 +++++++++++++++++++++++++++++++++++++++++ 2 files changed, 75 insertions(+) diff --git a/include/asm-generic/pci_iomap.h b/include/asm-generic/pci_iomap.h index 7389c87..b1e17fc 100644 --- a/include/asm-generic/pci_iomap.h +++ b/include/asm-generic/pci_iomap.h @@ -15,9 +15,13 @@ struct pci_dev; #ifdef CONFIG_PCI /* Create a virtual mapping cookie for a PCI BAR (memory or IO) */ extern void __iomem *pci_iomap(struct pci_dev *dev, int bar, unsigned long max); +extern void __iomem *pci_iomap_wc(struct pci_dev *dev, int bar, unsigned long max); extern void __iomem *pci_iomap_range(struct pci_dev *dev, int bar, unsigned long offset, unsigned long maxlen); +extern void __iomem *pci_iomap_wc_range(struct pci_dev *dev, int bar, + unsigned long offset, + unsigned long maxlen); /* Create a virtual mapping cookie for a port on a given PCI device. * Do not call this directly, it exists to make it easier for architectures * to override */ @@ -34,12 +38,22 @@ static inline void __iomem *pci_iomap(struct pci_dev *dev, int bar, unsigned lon return NULL; } +static inline void __iomem *pci_iomap_wc(struct pci_dev *dev, int bar, unsigned long max) +{ + return NULL; +} static inline void __iomem *pci_iomap_range(struct pci_dev *dev, int bar, unsigned long offset, unsigned long maxlen) { return NULL; } +static inline void __iomem *pci_iomap_wc_range(struct pci_dev *dev, int bar, + unsigned long offset, + unsigned long maxlen) +{ + return NULL; +} #endif #endif /* __ASM_GENERIC_IO_H */ diff --git a/lib/pci_iomap.c b/lib/pci_iomap.c index bcce5f1..9604dcb 100644 --- a/lib/pci_iomap.c +++ b/lib/pci_iomap.c @@ -52,6 +52,46 @@ void __iomem *pci_iomap_range(struct pci_dev *dev, EXPORT_SYMBOL(pci_iomap_range); /** + * pci_iomap_wc_range - create a virtual WC mapping cookie for a PCI BAR + * @dev: PCI device that owns the BAR + * @bar: BAR number + * @offset: map memory at the given offset in BAR + * @maxlen: max length of the memory to map + * + * Using this function you will get a __iomem address to your device BAR. + * You can access it using ioread*() and iowrite*(). These functions hide + * the details if this is a MMIO or PIO address space and will just do what + * you expect from them in the correct way. When possible write combining + * is used. + * + * @maxlen specifies the maximum length to map. If you want to get access to + * the complete BAR from offset to the end, pass %0 here. + * */ +void __iomem *pci_iomap_wc_range(struct pci_dev *dev, + int bar, + unsigned long offset, + unsigned long maxlen) +{ + resource_size_t start = pci_resource_start(dev, bar); + resource_size_t len = pci_resource_len(dev, bar); + unsigned long flags = pci_resource_flags(dev, bar); + + if (len <= offset || !start) + return NULL; + len -= offset; + start += offset; + if (maxlen && len > maxlen) + len = maxlen; + if (flags & IORESOURCE_IO) + return NULL; + if (flags & IORESOURCE_MEM) + return ioremap_wc(start, len); + /* What? */ + return NULL; +} +EXPORT_SYMBOL_GPL(pci_iomap_wc_range); + +/** * pci_iomap - create a virtual mapping cookie for a PCI BAR * @dev: PCI device that owns the BAR * @bar: BAR number @@ -70,4 +110,25 @@ void __iomem *pci_iomap(struct pci_dev *dev, int bar, unsigned long maxlen) return pci_iomap_range(dev, bar, 0, maxlen); } EXPORT_SYMBOL(pci_iomap); + +/** + * pci_iomap_wc - create a virtual WC mapping cookie for a PCI BAR + * @dev: PCI device that owns the BAR + * @bar: BAR number + * @maxlen: length of the memory to map + * + * Using this function you will get a __iomem address to your device BAR. + * You can access it using ioread*() and iowrite*(). These functions hide + * the details if this is a MMIO or PIO address space and will just do what + * you expect from them in the correct way. When possible write combining + * is used. + * + * @maxlen specifies the maximum length to map. If you want to get access to + * the complete BAR without checking for its length first, pass %0 here. + * */ +void __iomem *pci_iomap_wc(struct pci_dev *dev, int bar, unsigned long maxlen) +{ + return pci_iomap_wc_range(dev, bar, 0, maxlen); +} +EXPORT_SYMBOL_GPL(pci_iomap_wc); #endif /* CONFIG_PCI */ -- 2.3.2.209.gd67f9d5.dirty -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in Please read the FAQ at http://www.tux.org/lkml/ From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-f47.google.com ([209.85.220.47]:36734 "EHLO mail-pa0-f47.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751809AbbFSWVm (ORCPT ); Fri, 19 Jun 2015 18:21:42 -0400 From: "Luis R. Rodriguez" To: arnd@arndb.de Cc: linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, xen-devel@lists.xensource.com, linux-fbdev@vger.kernel.org, "Luis R. Rodriguez" , Toshi Kani , Andy Lutomirski , Suresh Siddha , Ingo Molnar , Thomas Gleixner , Juergen Gross , Daniel Vetter , Dave Airlie , Bjorn Helgaas , Antonino Daplas , Jean-Christophe Plagniol-Villard , Tomi Valkeinen , Dave Hansen , "Michael S. Tsirkin" , venkatesh.pallipadi@intel.com, Stefan Bader , =?UTF-8?q?Ville=20Syrj=C3=A4l=C3=A4?= , Mel Gorman , Vlastimil Babka , Borislav Petkov , Davidlohr Bueso , konrad.wilk@oracle.com, ville.syrjala@linux.intel.com, david.vrabel@citrix.com, jbeulich@suse.com, =?UTF-8?q?Roger=20Pau=20Monn=C3=A9?= Subject: [PATCH v7 5/9] PCI: Add pci_iomap_wc() variants Date: Fri, 19 Jun 2015 15:08:28 -0700 Message-Id: <1434751712-24333-6-git-send-email-mcgrof@do-not-panic.com> In-Reply-To: <1434751712-24333-1-git-send-email-mcgrof@do-not-panic.com> References: <1434751712-24333-1-git-send-email-mcgrof@do-not-panic.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-pci-owner@vger.kernel.org List-ID: From: "Luis R. Rodriguez" PCI BARs tell us whether prefetching is safe, but they don't say anything about write combining (WC). WC changes ordering rules and allows writes to be collapsed, so it's not safe in general to use it on a prefetchable region. Add pci_iomap_wc() and pci_iomap_wc_range() so drivers can take advantage of write combining when they know it's safe. On architectures that don't fully support WC, e.g., x86 without PAT, drivers for legacy framebuffers may get some of the benefit by using arch_phys_wc_add() in addition to pci_iomap_wc(). But arch_phys_wc_add() is unreliable and should be avoided in general. On x86, it uses MTRRs, which are limited in number and size, so the results will vary based on driver loading order. The goals of adding pci_iomap_wc() are to: - Give drivers an architecture-independent way to use WC so they can stop using interfaces like mtrr_add() (on x86, pci_iomap_wc() uses PAT when available) - Move toward using _PAGE_CACHE_MODE_UC, not _PAGE_CACHE_MODE_UC_MINUS, on x86 on ioremap_nocache() (see de33c442ed2a ("x86 PAT: fix performance drop for glx, use UC minus for ioremap(), ioremap_nocache() and pci_mmap_page_range()") Link: http://lkml.kernel.org/r/1426893517-2511-6-git-send-email-mcgrof@do-not-panic.com Original-posting: http://lkml.kernel.org/r/1432163293-20965-1-git-send-email-mcgrof@do-not-panic.com Cc: Toshi Kani Cc: Andy Lutomirski Cc: Suresh Siddha Cc: Ingo Molnar Cc: Thomas Gleixner Cc: Juergen Gross Cc: Daniel Vetter Cc: Dave Airlie Cc: Bjorn Helgaas Cc: Antonino Daplas Cc: Jean-Christophe Plagniol-Villard Cc: Tomi Valkeinen Cc: Dave Hansen Cc: Arnd Bergmann Cc: Michael S. Tsirkin Cc: venkatesh.pallipadi@intel.com Cc: Stefan Bader Cc: Ville Syrjälä Cc: Mel Gorman Cc: Vlastimil Babka Cc: Borislav Petkov Cc: Davidlohr Bueso Cc: konrad.wilk@oracle.com Cc: ville.syrjala@linux.intel.com Cc: david.vrabel@citrix.com Cc: jbeulich@suse.com Cc: Roger Pau Monné Cc: linux-fbdev@vger.kernel.org Cc: linux-kernel@vger.kernel.org Cc: xen-devel@lists.xensource.com Signed-off-by: Luis R. Rodriguez --- include/asm-generic/pci_iomap.h | 14 ++++++++++ lib/pci_iomap.c | 61 +++++++++++++++++++++++++++++++++++++++++ 2 files changed, 75 insertions(+) diff --git a/include/asm-generic/pci_iomap.h b/include/asm-generic/pci_iomap.h index 7389c87..b1e17fc 100644 --- a/include/asm-generic/pci_iomap.h +++ b/include/asm-generic/pci_iomap.h @@ -15,9 +15,13 @@ struct pci_dev; #ifdef CONFIG_PCI /* Create a virtual mapping cookie for a PCI BAR (memory or IO) */ extern void __iomem *pci_iomap(struct pci_dev *dev, int bar, unsigned long max); +extern void __iomem *pci_iomap_wc(struct pci_dev *dev, int bar, unsigned long max); extern void __iomem *pci_iomap_range(struct pci_dev *dev, int bar, unsigned long offset, unsigned long maxlen); +extern void __iomem *pci_iomap_wc_range(struct pci_dev *dev, int bar, + unsigned long offset, + unsigned long maxlen); /* Create a virtual mapping cookie for a port on a given PCI device. * Do not call this directly, it exists to make it easier for architectures * to override */ @@ -34,12 +38,22 @@ static inline void __iomem *pci_iomap(struct pci_dev *dev, int bar, unsigned lon return NULL; } +static inline void __iomem *pci_iomap_wc(struct pci_dev *dev, int bar, unsigned long max) +{ + return NULL; +} static inline void __iomem *pci_iomap_range(struct pci_dev *dev, int bar, unsigned long offset, unsigned long maxlen) { return NULL; } +static inline void __iomem *pci_iomap_wc_range(struct pci_dev *dev, int bar, + unsigned long offset, + unsigned long maxlen) +{ + return NULL; +} #endif #endif /* __ASM_GENERIC_IO_H */ diff --git a/lib/pci_iomap.c b/lib/pci_iomap.c index bcce5f1..9604dcb 100644 --- a/lib/pci_iomap.c +++ b/lib/pci_iomap.c @@ -52,6 +52,46 @@ void __iomem *pci_iomap_range(struct pci_dev *dev, EXPORT_SYMBOL(pci_iomap_range); /** + * pci_iomap_wc_range - create a virtual WC mapping cookie for a PCI BAR + * @dev: PCI device that owns the BAR + * @bar: BAR number + * @offset: map memory at the given offset in BAR + * @maxlen: max length of the memory to map + * + * Using this function you will get a __iomem address to your device BAR. + * You can access it using ioread*() and iowrite*(). These functions hide + * the details if this is a MMIO or PIO address space and will just do what + * you expect from them in the correct way. When possible write combining + * is used. + * + * @maxlen specifies the maximum length to map. If you want to get access to + * the complete BAR from offset to the end, pass %0 here. + * */ +void __iomem *pci_iomap_wc_range(struct pci_dev *dev, + int bar, + unsigned long offset, + unsigned long maxlen) +{ + resource_size_t start = pci_resource_start(dev, bar); + resource_size_t len = pci_resource_len(dev, bar); + unsigned long flags = pci_resource_flags(dev, bar); + + if (len <= offset || !start) + return NULL; + len -= offset; + start += offset; + if (maxlen && len > maxlen) + len = maxlen; + if (flags & IORESOURCE_IO) + return NULL; + if (flags & IORESOURCE_MEM) + return ioremap_wc(start, len); + /* What? */ + return NULL; +} +EXPORT_SYMBOL_GPL(pci_iomap_wc_range); + +/** * pci_iomap - create a virtual mapping cookie for a PCI BAR * @dev: PCI device that owns the BAR * @bar: BAR number @@ -70,4 +110,25 @@ void __iomem *pci_iomap(struct pci_dev *dev, int bar, unsigned long maxlen) return pci_iomap_range(dev, bar, 0, maxlen); } EXPORT_SYMBOL(pci_iomap); + +/** + * pci_iomap_wc - create a virtual WC mapping cookie for a PCI BAR + * @dev: PCI device that owns the BAR + * @bar: BAR number + * @maxlen: length of the memory to map + * + * Using this function you will get a __iomem address to your device BAR. + * You can access it using ioread*() and iowrite*(). These functions hide + * the details if this is a MMIO or PIO address space and will just do what + * you expect from them in the correct way. When possible write combining + * is used. + * + * @maxlen specifies the maximum length to map. If you want to get access to + * the complete BAR without checking for its length first, pass %0 here. + * */ +void __iomem *pci_iomap_wc(struct pci_dev *dev, int bar, unsigned long maxlen) +{ + return pci_iomap_wc_range(dev, bar, 0, maxlen); +} +EXPORT_SYMBOL_GPL(pci_iomap_wc); #endif /* CONFIG_PCI */ -- 2.3.2.209.gd67f9d5.dirty -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Luis R. Rodriguez" Date: Fri, 19 Jun 2015 22:08:28 +0000 Subject: [PATCH v7 5/9] PCI: Add pci_iomap_wc() variants Message-Id: <1434751712-24333-6-git-send-email-mcgrof@do-not-panic.com> List-Id: References: <1434751712-24333-1-git-send-email-mcgrof@do-not-panic.com> In-Reply-To: <1434751712-24333-1-git-send-email-mcgrof@do-not-panic.com> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 8bit To: arnd@arndb.de Cc: linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, xen-devel@lists.xensource.com, linux-fbdev@vger.kernel.org, "Luis R. Rodriguez" , Toshi Kani , Andy Lutomirski , Suresh Siddha , Ingo Molnar , Thomas Gleixner , Juergen Gross , Daniel Vetter , Dave Airlie , Bjorn Helgaas , Antonino Daplas , Jean-Christophe Plagniol-Villard , Tomi Valkeinen , Dave Hansen , "Michael S. Tsirkin" , venkatesh.pallipadi@intel.com, Stefan Bader , =?UTF-8?q?Ville=20Syrj=C3=A4l=C3=A4?= , Mel Gorman , Vlastimil Babka , Borislav Petkov , Davidlohr Bueso , konrad.wilk@oracle.com, ville.syrjala@linux.intel.com, david.vrabel@citrix.com, jbeulich@suse.com, =?UTF-8?q?Roger=20Pau=20Monn=C3=A9?= From: "Luis R. Rodriguez" PCI BARs tell us whether prefetching is safe, but they don't say anything about write combining (WC). WC changes ordering rules and allows writes to be collapsed, so it's not safe in general to use it on a prefetchable region. Add pci_iomap_wc() and pci_iomap_wc_range() so drivers can take advantage of write combining when they know it's safe. On architectures that don't fully support WC, e.g., x86 without PAT, drivers for legacy framebuffers may get some of the benefit by using arch_phys_wc_add() in addition to pci_iomap_wc(). But arch_phys_wc_add() is unreliable and should be avoided in general. On x86, it uses MTRRs, which are limited in number and size, so the results will vary based on driver loading order. The goals of adding pci_iomap_wc() are to: - Give drivers an architecture-independent way to use WC so they can stop using interfaces like mtrr_add() (on x86, pci_iomap_wc() uses PAT when available) - Move toward using _PAGE_CACHE_MODE_UC, not _PAGE_CACHE_MODE_UC_MINUS, on x86 on ioremap_nocache() (see de33c442ed2a ("x86 PAT: fix performance drop for glx, use UC minus for ioremap(), ioremap_nocache() and pci_mmap_page_range()") Link: http://lkml.kernel.org/r/1426893517-2511-6-git-send-email-mcgrof@do-not-panic.com Original-posting: http://lkml.kernel.org/r/1432163293-20965-1-git-send-email-mcgrof@do-not-panic.com Cc: Toshi Kani Cc: Andy Lutomirski Cc: Suresh Siddha Cc: Ingo Molnar Cc: Thomas Gleixner Cc: Juergen Gross Cc: Daniel Vetter Cc: Dave Airlie Cc: Bjorn Helgaas Cc: Antonino Daplas Cc: Jean-Christophe Plagniol-Villard Cc: Tomi Valkeinen Cc: Dave Hansen Cc: Arnd Bergmann Cc: Michael S. Tsirkin Cc: venkatesh.pallipadi@intel.com Cc: Stefan Bader Cc: Ville Syrjälä Cc: Mel Gorman Cc: Vlastimil Babka Cc: Borislav Petkov Cc: Davidlohr Bueso Cc: konrad.wilk@oracle.com Cc: ville.syrjala@linux.intel.com Cc: david.vrabel@citrix.com Cc: jbeulich@suse.com Cc: Roger Pau Monné Cc: linux-fbdev@vger.kernel.org Cc: linux-kernel@vger.kernel.org Cc: xen-devel@lists.xensource.com Signed-off-by: Luis R. Rodriguez --- include/asm-generic/pci_iomap.h | 14 ++++++++++ lib/pci_iomap.c | 61 +++++++++++++++++++++++++++++++++++++++++ 2 files changed, 75 insertions(+) diff --git a/include/asm-generic/pci_iomap.h b/include/asm-generic/pci_iomap.h index 7389c87..b1e17fc 100644 --- a/include/asm-generic/pci_iomap.h +++ b/include/asm-generic/pci_iomap.h @@ -15,9 +15,13 @@ struct pci_dev; #ifdef CONFIG_PCI /* Create a virtual mapping cookie for a PCI BAR (memory or IO) */ extern void __iomem *pci_iomap(struct pci_dev *dev, int bar, unsigned long max); +extern void __iomem *pci_iomap_wc(struct pci_dev *dev, int bar, unsigned long max); extern void __iomem *pci_iomap_range(struct pci_dev *dev, int bar, unsigned long offset, unsigned long maxlen); +extern void __iomem *pci_iomap_wc_range(struct pci_dev *dev, int bar, + unsigned long offset, + unsigned long maxlen); /* Create a virtual mapping cookie for a port on a given PCI device. * Do not call this directly, it exists to make it easier for architectures * to override */ @@ -34,12 +38,22 @@ static inline void __iomem *pci_iomap(struct pci_dev *dev, int bar, unsigned lon return NULL; } +static inline void __iomem *pci_iomap_wc(struct pci_dev *dev, int bar, unsigned long max) +{ + return NULL; +} static inline void __iomem *pci_iomap_range(struct pci_dev *dev, int bar, unsigned long offset, unsigned long maxlen) { return NULL; } +static inline void __iomem *pci_iomap_wc_range(struct pci_dev *dev, int bar, + unsigned long offset, + unsigned long maxlen) +{ + return NULL; +} #endif #endif /* __ASM_GENERIC_IO_H */ diff --git a/lib/pci_iomap.c b/lib/pci_iomap.c index bcce5f1..9604dcb 100644 --- a/lib/pci_iomap.c +++ b/lib/pci_iomap.c @@ -52,6 +52,46 @@ void __iomem *pci_iomap_range(struct pci_dev *dev, EXPORT_SYMBOL(pci_iomap_range); /** + * pci_iomap_wc_range - create a virtual WC mapping cookie for a PCI BAR + * @dev: PCI device that owns the BAR + * @bar: BAR number + * @offset: map memory at the given offset in BAR + * @maxlen: max length of the memory to map + * + * Using this function you will get a __iomem address to your device BAR. + * You can access it using ioread*() and iowrite*(). These functions hide + * the details if this is a MMIO or PIO address space and will just do what + * you expect from them in the correct way. When possible write combining + * is used. + * + * @maxlen specifies the maximum length to map. If you want to get access to + * the complete BAR from offset to the end, pass %0 here. + * */ +void __iomem *pci_iomap_wc_range(struct pci_dev *dev, + int bar, + unsigned long offset, + unsigned long maxlen) +{ + resource_size_t start = pci_resource_start(dev, bar); + resource_size_t len = pci_resource_len(dev, bar); + unsigned long flags = pci_resource_flags(dev, bar); + + if (len <= offset || !start) + return NULL; + len -= offset; + start += offset; + if (maxlen && len > maxlen) + len = maxlen; + if (flags & IORESOURCE_IO) + return NULL; + if (flags & IORESOURCE_MEM) + return ioremap_wc(start, len); + /* What? */ + return NULL; +} +EXPORT_SYMBOL_GPL(pci_iomap_wc_range); + +/** * pci_iomap - create a virtual mapping cookie for a PCI BAR * @dev: PCI device that owns the BAR * @bar: BAR number @@ -70,4 +110,25 @@ void __iomem *pci_iomap(struct pci_dev *dev, int bar, unsigned long maxlen) return pci_iomap_range(dev, bar, 0, maxlen); } EXPORT_SYMBOL(pci_iomap); + +/** + * pci_iomap_wc - create a virtual WC mapping cookie for a PCI BAR + * @dev: PCI device that owns the BAR + * @bar: BAR number + * @maxlen: length of the memory to map + * + * Using this function you will get a __iomem address to your device BAR. + * You can access it using ioread*() and iowrite*(). These functions hide + * the details if this is a MMIO or PIO address space and will just do what + * you expect from them in the correct way. When possible write combining + * is used. + * + * @maxlen specifies the maximum length to map. If you want to get access to + * the complete BAR without checking for its length first, pass %0 here. + * */ +void __iomem *pci_iomap_wc(struct pci_dev *dev, int bar, unsigned long maxlen) +{ + return pci_iomap_wc_range(dev, bar, 0, maxlen); +} +EXPORT_SYMBOL_GPL(pci_iomap_wc); #endif /* CONFIG_PCI */ -- 2.3.2.209.gd67f9d5.dirty -- To unsubscribe from this list: send the line "unsubscribe linux-fbdev" in From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Luis R. Rodriguez" Subject: [PATCH v7 5/9] PCI: Add pci_iomap_wc() variants Date: Fri, 19 Jun 2015 15:08:28 -0700 Message-ID: <1434751712-24333-6-git-send-email-mcgrof@do-not-panic.com> References: <1434751712-24333-1-git-send-email-mcgrof@do-not-panic.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: <1434751712-24333-1-git-send-email-mcgrof@do-not-panic.com> Sender: linux-pci-owner@vger.kernel.org To: arnd@arndb.de Cc: linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, xen-devel@lists.xensource.com, linux-fbdev@vger.kernel.org, "Luis R. Rodriguez" , Toshi Kani , Andy Lutomirski , Suresh Siddha , Ingo Molnar , Thomas Gleixner , Juergen Gross , Daniel Vetter , Dave Airlie , Bjorn Helgaas , Antonino Daplas , Jean-Christophe Plagniol-Villard , Tomi Valkeinen , Dave Hansen , "Michael S. Tsirkin" , venkatesh.pallipadi@intel.com, Stefan Bader , =?UTF-8?q?Ville=20Syrj=C3=A4l=C3=A4?= , Mel Gorman , Vlastimil Babka List-Id: xen-devel@lists.xenproject.org =46rom: "Luis R. Rodriguez" PCI BARs tell us whether prefetching is safe, but they don't say anythi= ng about write combining (WC). WC changes ordering rules and allows write= s to be collapsed, so it's not safe in general to use it on a prefetchable region. Add pci_iomap_wc() and pci_iomap_wc_range() so drivers can take advanta= ge of write combining when they know it's safe. On architectures that don't fully support WC, e.g., x86 without PAT, drivers for legacy framebuffers may get some of the benefit by using arch_phys_wc_add() in addition to pci_iomap_wc(). But arch_phys_wc_add= () is unreliable and should be avoided in general. On x86, it uses MTRRs, which are limited in number and size, so the results will vary based on driver loading order. The goals of adding pci_iomap_wc() are to: - Give drivers an architecture-independent way to use WC so they can st= op using interfaces like mtrr_add() (on x86, pci_iomap_wc() uses PAT when available) - Move toward using _PAGE_CACHE_MODE_UC, not _PAGE_CACHE_MODE_UC_MINUS, on x86 on ioremap_nocache() (see de33c442ed2a ("x86 PAT: fix performance drop for glx, use UC minus for ioremap(), ioremap_nocache= () and pci_mmap_page_range()") Link: http://lkml.kernel.org/r/1426893517-2511-6-git-send-email-mcgrof@= do-not-panic.com Original-posting: http://lkml.kernel.org/r/1432163293-20965-1-git-send-= email-mcgrof@do-not-panic.com Cc: Toshi Kani Cc: Andy Lutomirski Cc: Suresh Siddha Cc: Ingo Molnar Cc: Thomas Gleixner Cc: Juergen Gross Cc: Daniel Vetter Cc: Dave Airlie Cc: Bjorn Helgaas Cc: Antonino Daplas Cc: Jean-Christophe Plagniol-Villard Cc: Tomi Valkeinen Cc: Dave Hansen Cc: Arnd Bergmann Cc: Michael S. Tsirkin Cc: venkatesh.pallipadi@intel.com Cc: Stefan Bader Cc: Ville Syrj=C3=A4l=C3=A4 Cc: Mel Gorman Cc: Vlastimil Babka Cc: Borislav Petkov Cc: Davidlohr Bueso Cc: konrad.wilk@oracle.com Cc: ville.syrjala@linux.intel.com Cc: david.vrabel@citrix.com Cc: jbeulich@suse.com Cc: Roger Pau Monn=C3=A9 Cc: linux-fbdev@vger.kernel.org Cc: linux-kernel@vger.kernel.org Cc: xen-devel@lists.xensource.com Signed-off-by: Luis R. Rodriguez --- include/asm-generic/pci_iomap.h | 14 ++++++++++ lib/pci_iomap.c | 61 +++++++++++++++++++++++++++++++++= ++++++++ 2 files changed, 75 insertions(+) diff --git a/include/asm-generic/pci_iomap.h b/include/asm-generic/pci_= iomap.h index 7389c87..b1e17fc 100644 --- a/include/asm-generic/pci_iomap.h +++ b/include/asm-generic/pci_iomap.h @@ -15,9 +15,13 @@ struct pci_dev; #ifdef CONFIG_PCI /* Create a virtual mapping cookie for a PCI BAR (memory or IO) */ extern void __iomem *pci_iomap(struct pci_dev *dev, int bar, unsigned = long max); +extern void __iomem *pci_iomap_wc(struct pci_dev *dev, int bar, unsign= ed long max); extern void __iomem *pci_iomap_range(struct pci_dev *dev, int bar, unsigned long offset, unsigned long maxlen); +extern void __iomem *pci_iomap_wc_range(struct pci_dev *dev, int bar, + unsigned long offset, + unsigned long maxlen); /* Create a virtual mapping cookie for a port on a given PCI device. * Do not call this directly, it exists to make it easier for architec= tures * to override */ @@ -34,12 +38,22 @@ static inline void __iomem *pci_iomap(struct pci_de= v *dev, int bar, unsigned lon return NULL; } =20 +static inline void __iomem *pci_iomap_wc(struct pci_dev *dev, int bar,= unsigned long max) +{ + return NULL; +} static inline void __iomem *pci_iomap_range(struct pci_dev *dev, int b= ar, unsigned long offset, unsigned long maxlen) { return NULL; } +static inline void __iomem *pci_iomap_wc_range(struct pci_dev *dev, in= t bar, + unsigned long offset, + unsigned long maxlen) +{ + return NULL; +} #endif =20 #endif /* __ASM_GENERIC_IO_H */ diff --git a/lib/pci_iomap.c b/lib/pci_iomap.c index bcce5f1..9604dcb 100644 --- a/lib/pci_iomap.c +++ b/lib/pci_iomap.c @@ -52,6 +52,46 @@ void __iomem *pci_iomap_range(struct pci_dev *dev, EXPORT_SYMBOL(pci_iomap_range); =20 /** + * pci_iomap_wc_range - create a virtual WC mapping cookie for a PCI B= AR + * @dev: PCI device that owns the BAR + * @bar: BAR number + * @offset: map memory at the given offset in BAR + * @maxlen: max length of the memory to map + * + * Using this function you will get a __iomem address to your device B= AR. + * You can access it using ioread*() and iowrite*(). These functions h= ide + * the details if this is a MMIO or PIO address space and will just do= what + * you expect from them in the correct way. When possible write combin= ing + * is used. + * + * @maxlen specifies the maximum length to map. If you want to get acc= ess to + * the complete BAR from offset to the end, pass %0 here. + * */ +void __iomem *pci_iomap_wc_range(struct pci_dev *dev, + int bar, + unsigned long offset, + unsigned long maxlen) +{ + resource_size_t start =3D pci_resource_start(dev, bar); + resource_size_t len =3D pci_resource_len(dev, bar); + unsigned long flags =3D pci_resource_flags(dev, bar); + + if (len <=3D offset || !start) + return NULL; + len -=3D offset; + start +=3D offset; + if (maxlen && len > maxlen) + len =3D maxlen; + if (flags & IORESOURCE_IO) + return NULL; + if (flags & IORESOURCE_MEM) + return ioremap_wc(start, len); + /* What? */ + return NULL; +} +EXPORT_SYMBOL_GPL(pci_iomap_wc_range); + +/** * pci_iomap - create a virtual mapping cookie for a PCI BAR * @dev: PCI device that owns the BAR * @bar: BAR number @@ -70,4 +110,25 @@ void __iomem *pci_iomap(struct pci_dev *dev, int ba= r, unsigned long maxlen) return pci_iomap_range(dev, bar, 0, maxlen); } EXPORT_SYMBOL(pci_iomap); + +/** + * pci_iomap_wc - create a virtual WC mapping cookie for a PCI BAR + * @dev: PCI device that owns the BAR + * @bar: BAR number + * @maxlen: length of the memory to map + * + * Using this function you will get a __iomem address to your device B= AR. + * You can access it using ioread*() and iowrite*(). These functions h= ide + * the details if this is a MMIO or PIO address space and will just do= what + * you expect from them in the correct way. When possible write combin= ing + * is used. + * + * @maxlen specifies the maximum length to map. If you want to get acc= ess to + * the complete BAR without checking for its length first, pass %0 her= e. + * */ +void __iomem *pci_iomap_wc(struct pci_dev *dev, int bar, unsigned long= maxlen) +{ + return pci_iomap_wc_range(dev, bar, 0, maxlen); +} +EXPORT_SYMBOL_GPL(pci_iomap_wc); #endif /* CONFIG_PCI */ --=20 2.3.2.209.gd67f9d5.dirty