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

Commit Message

Luis R. Rodriguez Aug. 24, 2015, 7:13 p.m. UTC

From: "Luis R. Rodriguez" <[e-mail]>

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 <[e-mail]>
Acked-by: Arnd Bergmann <[e-mail]>
Cc: Andrew Morton <[e-mail]>
Cc: Andy Lutomirski <[e-mail]>
Cc: Antonino Daplas <[e-mail]>
Cc: [e-mail]
Cc: Bjorn Helgaas <[e-mail]>
Cc: Daniel Vetter <[e-mail]>
Cc: Dave Airlie <[e-mail]>
Cc: Davidlohr Bueso <[e-mail]>
Cc: H. Peter Anvin <[e-mail]>
Cc: Ingo Molnar <[e-mail]>
Cc: Jean-Christophe Plagniol-Villard <[e-mail]>
Cc: Juergen Gross <[e-mail]>
Cc: [e-mail]
Cc: [e-mail]
Cc: Mel Gorman <[e-mail]>
Cc: [e-mail]
Cc: Suresh Siddha <[e-mail]>
Cc: Thomas Gleixner <[e-mail]>
Cc: Tomi Valkeinen <[e-mail]>
Cc: Toshi Kani <[e-mail]>
Cc: Ville Syrjälä <[e-mail]>
Cc: Vlastimil Babka <[e-mail]>
Link: http://lkml.kernel.org/r/[e-mail]
Signed-off-by: Borislav Petkov <[e-mail]>
---
 drivers/pci/pci.c   | 14 ++++++++++++++
 include/linux/pci.h |  1 +
 2 files changed, 15 insertions(+)

Patch

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);