linux-kernel - [PATCH v8 1/9] pci: add pci_ioremap_wc

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Date:	Wed, 24 Jun 2015 18:22:14 -0700
From:	"Luis R. Rodriguez" <mcgrof@...not-panic.com>
To:	bp@...e.de
Cc:	mingo@...nel.org, arnd@...db.de, bhelgaas@...gle.com,
	luto@...capital.net, akpm@...ux-foundation.org,
	linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org,
	tomi.valkeinen@...com, mst@...hat.com, toshi.kani@...com,
	linux-fbdev@...r.kernel.org, xen-devel@...ts.xensource.com,
	benh@...nel.crashing.org, "Luis R. Rodriguez" <mcgrof@...e.com>,
	Suresh Siddha <sbsiddha@...il.com>,
	Ingo Molnar <mingo@...e.hu>,
	Thomas Gleixner <tglx@...utronix.de>,
	Juergen Gross <jgross@...e.com>,
	Daniel Vetter <daniel.vetter@...ll.ch>,
	Dave Airlie <airlied@...hat.com>,
	Antonino Daplas <adaplas@...il.com>,
	Jean-Christophe Plagniol-Villard <plagnioj@...osoft.com>,
	Ville Syrjälä <syrjala@....fi>,
	Mel Gorman <mgorman@...e.de>, Vlastimil Babka <vbabka@...e.cz>,
	Davidlohr Bueso <dbueso@...e.de>
Subject: [PATCH v8 1/9] pci: add pci_ioremap_wc_bar()

From: "Luis R. Rodriguez" <mcgrof@...e.com>

This lets drivers take advantage of PAT when available. This
should help with the transition of converting video drivers over
to ioremap_wc() to help with the goal of eventually using
_PAGE_CACHE_UC over _PAGE_CACHE_UC_MINUS on x86 on
ioremap_nocache() (de33c442e titled "x86 PAT: fix performance
drop for glx, use UC minus for ioremap(), ioremap_nocache() and
pci_mmap_page_range()")

Cc: Toshi Kani <toshi.kani@...com>
Cc: Bjorn Helgaas <bhelgaas@...gle.com>
Cc: Suresh Siddha <sbsiddha@...il.com>
Cc: Ingo Molnar <mingo@...e.hu>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Juergen Gross <jgross@...e.com>
Cc: Daniel Vetter <daniel.vetter@...ll.ch>
Cc: Andy Lutomirski <luto@...capital.net>
Cc: Dave Airlie <airlied@...hat.com>
Cc: Antonino Daplas <adaplas@...il.com>
Cc: Jean-Christophe Plagniol-Villard <plagnioj@...osoft.com>
Cc: Tomi Valkeinen <tomi.valkeinen@...com>
Cc: Ville Syrjälä <syrjala@....fi>
Cc: Mel Gorman <mgorman@...e.de>
Cc: Vlastimil Babka <vbabka@...e.cz>
Cc: Borislav Petkov <bp@...e.de>
Cc: Davidlohr Bueso <dbueso@...e.de>
Cc: linux-fbdev@...r.kernel.org
Cc: linux-kernel@...r.kernel.org
Acked-by: Arnd Bergmann <arnd@...db.de>
Signed-off-by: Luis R. Rodriguez <mcgrof@...e.com>
---
 drivers/pci/pci.c   | 14 ++++++++++++++
 include/linux/pci.h |  1 +
 2 files changed, 15 insertions(+)

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 0008c95..fdae37b 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -138,6 +138,20 @@ void __iomem *pci_ioremap_bar(struct pci_dev *pdev, int bar)
 	return ioremap_nocache(res->start, resource_size(res));
 }
 EXPORT_SYMBOL_GPL(pci_ioremap_bar);
+
+void __iomem *pci_ioremap_wc_bar(struct pci_dev *pdev, int bar)
+{
+	/*
+	 * Make sure the BAR is actually a memory resource, not an IO resource
+	 */
+	if (!(pci_resource_flags(pdev, bar) & IORESOURCE_MEM)) {
+		WARN_ON(1);
+		return NULL;
+	}
+	return ioremap_wc(pci_resource_start(pdev, bar),
+			  pci_resource_len(pdev, bar));
+}
+EXPORT_SYMBOL_GPL(pci_ioremap_wc_bar);
 #endif
 
 #define PCI_FIND_CAP_TTL	48
diff --git a/include/linux/pci.h b/include/linux/pci.h
index c0dd4ab..1193975 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -1657,6 +1657,7 @@ static inline void pci_mmcfg_late_init(void) { }
 int pci_ext_cfg_avail(void);
 
 void __iomem *pci_ioremap_bar(struct pci_dev *pdev, int bar);
+void __iomem *pci_ioremap_wc_bar(struct pci_dev *pdev, int bar);
 
 #ifdef CONFIG_PCI_IOV
 int pci_iov_virtfn_bus(struct pci_dev *dev, int id);
-- 
2.3.2.209.gd67f9d5.dirty

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