From patchwork Thu Jun 25 01:22:18 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: "Luis R. Rodriguez" X-Patchwork-Id: 6671691 Return-Path: X-Original-To: patchwork-linux-fbdev@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork2.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork2.web.kernel.org (Postfix) with ESMTP id 6BB45C05AC for ; Thu, 25 Jun 2015 01:35:51 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 6851B20574 for ; Thu, 25 Jun 2015 01:35:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id BF17C20562 for ; Thu, 25 Jun 2015 01:35:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752027AbbFYBfh (ORCPT ); Wed, 24 Jun 2015 21:35:37 -0400 Received: from mail-pd0-f182.google.com ([209.85.192.182]:35383 "EHLO mail-pd0-f182.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751017AbbFYBfg (ORCPT ); Wed, 24 Jun 2015 21:35:36 -0400 Received: by pdbci14 with SMTP id ci14so41951662pdb.2; Wed, 24 Jun 2015 18:35:35 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=sender:from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-type:content-transfer-encoding; bh=aM6wQD8+/hd/U1p8OyRLfdaHv5AeOg1s0LkdZcB1cBA=; b=NlKnNcSx6snnu34uQmlypCqBKrd7H1zQ+3Iw+j1Eh3lmF7XBG9/h7r/d6lLNnM7W9C Ulsk8qpNz/KXhIG+xvA+MsKMlS4SgFbwmSOL5rrMbyP5GScDPy7iTaTeAXxYBWWeZ5vJ Oi7Y34FqvByctVYbq/Qx80CFw0lPU6kU7JkFlnwWRDN8wcPfAHBbza6p6HMDQN5X23LT OrZGSfWLN8+74R4/FyfbqRAeLucnCjAmofyUcY9TBCbs3G0KG9VWrqWap6G2nhe7LMiz sB3hex/ueL14ggifVYR5udgPmS344cCEZPkgWOyHYg+ajq2MiiCr7b+TvzsihgRarWMh bt+A== X-Received: by 10.68.125.130 with SMTP id mq2mr84406137pbb.121.1435196135533; Wed, 24 Jun 2015 18:35:35 -0700 (PDT) Received: from mcgrof@gmail.com (c-98-234-145-61.hsd1.ca.comcast.net. [98.234.145.61]) by mx.google.com with ESMTPSA id nq2sm28110066pdb.70.2015.06.24.18.35.31 (version=TLSv1 cipher=RC4-SHA bits=128/128); Wed, 24 Jun 2015 18:35:34 -0700 (PDT) Received: by mcgrof@gmail.com (sSMTP sendmail emulation); Wed, 24 Jun 2015 18:33:24 -0700 From: "Luis R. Rodriguez" To: bp@suse.de Cc: mingo@kernel.org, arnd@arndb.de, bhelgaas@google.com, luto@amacapital.net, akpm@linux-foundation.org, linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, tomi.valkeinen@ti.com, mst@redhat.com, toshi.kani@hp.com, linux-fbdev@vger.kernel.org, xen-devel@lists.xensource.com, benh@kernel.crashing.org, "Luis R. Rodriguez" , Suresh Siddha , Ingo Molnar , Thomas Gleixner , Juergen Gross , Daniel Vetter , Dave Airlie , Antonino Daplas , Jean-Christophe Plagniol-Villard , Dave Hansen , venkatesh.pallipadi@intel.com, Stefan Bader , =?UTF-8?q?Ville=20Syrj=C3=A4l=C3=A4?= , Mel Gorman , Vlastimil Babka , 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 v8 5/9] PCI: Add pci_iomap_wc() variants Date: Wed, 24 Jun 2015 18:22:18 -0700 Message-Id: <1435195342-26879-6-git-send-email-mcgrof@do-not-panic.com> X-Mailer: git-send-email 2.1.4 In-Reply-To: <1435195342-26879-1-git-send-email-mcgrof@do-not-panic.com> References: <1435195342-26879-1-git-send-email-mcgrof@do-not-panic.com> MIME-Version: 1.0 Sender: linux-fbdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fbdev@vger.kernel.org X-Spam-Status: No, score=-3.2 required=5.0 tests=BAYES_00,DKIM_SIGNED, RP_MATCHES_RCVD, T_DKIM_INVALID, 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 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 Acked-by: Arnd Bergmann 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 */