From: "Luis R. Rodriguez" <redacted>

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 <redacted>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Suresh Siddha <redacted>
Cc: Ingo Molnar <redacted>
Cc: Thomas Gleixner <redacted>
Cc: Juergen Gross <jgross@suse.com>
Cc: Daniel Vetter <redacted>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Dave Airlie <airlied@redhat.com>
Cc: Antonino Daplas <adaplas@gmail.com>
Cc: Jean-Christophe Plagniol-Villard <redacted>
Cc: Tomi Valkeinen <redacted>
Cc: Ville Syrjälä <syrjala@sci.fi>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Vlastimil Babka <redacted>
Cc: Borislav Petkov <redacted>
Cc: Davidlohr Bueso <redacted>
Cc: linux-fbdev@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Luis R. Rodriguez <redacted>
---
 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