[PATCH v4 01/11] PCI: Add pci_ioremap_wc_bar()

["Luis R. Rodriguez" <mcgrof@do-not-panic.com>]

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

This lets drivers take advantage of PAT when available. It 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(), see:

  de33c442ed2a ("x86 PAT: fix performance drop for glx, use UC minus for ioremap(),
		ioremap_nocache() and pci_mmap_page_range()")

Signed-off-by: Luis R. Rodriguez <mcgrof@suse.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Antonino Daplas <adaplas@gmail.com>
Cc: benh@kernel.crashing.org
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Dave Airlie <airlied@redhat.com>
Cc: Davidlohr Bueso <dbueso@suse.de>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jean-Christophe Plagniol-Villard <plagnioj@jcrosoft.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: linux-fbdev@vger.kernel.org
Cc: linux-pci@vger.kernel.org
Cc: Mel Gorman <mgorman@suse.de>
Cc: mst@redhat.com
Cc: Suresh Siddha <sbsiddha@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tomi Valkeinen <tomi.valkeinen@ti.com>
Cc: Toshi Kani <toshi.kani@hp.com>
Cc: Ville Syrjälä <syrjala@sci.fi>
Cc: Vlastimil Babka <vbabka@suse.cz>
Link: http://lkml.kernel.org/r/1435195342-26879-2-git-send-email-mcgrof@do-not-panic.com
Signed-off-by: Borislav Petkov <bp@suse.de>
---
 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 8037c27beb05..33867b8a4bc9 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
 
 
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 88bee285b93d..2b2d7d44c21a 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -1701,6 +1701,7 @@ 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);
-- 
2.4.3