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Commit ae749c7a authored by David Woodhouse's avatar David Woodhouse Committed by Bjorn Helgaas
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PCI: Add arch_can_pci_mmap_wc() macro 



Most of the almost-identical versions of pci_mmap_page_range() silently
ignore the 'write_combine' argument and give uncached mappings.

Yet we allow the PCIIOC_WRITE_COMBINE ioctl in /proc/bus/pci, expose the
'resourceX_wc' file in sysfs, and allow an attempted mapping to apparently
succeed.

To fix this, introduce a macro arch_can_pci_mmap_wc() which indicates
whether the platform can do a write-combining mapping.  On x86 this ends up
being pat_enabled(), while the few other platforms that support it can just
set it to a literal '1'.

Signed-off-by: default avatarDavid Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: default avatarBjorn Helgaas <bhelgaas@google.com>
parent 03a064b4

Documentation/filesystems/sysfs-pci.txt

+4 −0
Original line number Diff line number Diff line
@@ -117,6 +117,10 @@ code must define HAVE_PCI_MMAP and provide a pci_mmap_page_range function. 
Platforms are free to only support subsets of the mmap functionality, but

useful return codes should be provided.



Platforms which support write-combining maps of PCI resources must define

arch_can_pci_mmap_wc() which shall evaluate to non-zero at runtime when

write-combining is permitted.



Legacy resources are protected by the HAVE_PCI_LEGACY define.  Platforms

wishing to support legacy functionality should define it and provide

pci_legacy_read, pci_legacy_write and pci_mmap_legacy_page_range functions.

arch/ia64/include/asm/pci.h

+2 −0
Original line number Diff line number Diff line
@@ -51,6 +51,8 @@ extern unsigned long ia64_max_iommu_merge_mask; 
#define PCI_DMA_BUS_IS_PHYS	(ia64_max_iommu_merge_mask == ~0UL)



#define HAVE_PCI_MMAP

#define arch_can_pci_mmap_wc()	1



extern int pci_mmap_page_range (struct pci_dev *dev, struct vm_area_struct *vma,

				enum pci_mmap_state mmap_state, int write_combine);

#define HAVE_PCI_LEGACY

arch/powerpc/include/asm/pci.h

+3 −2
Original line number Diff line number Diff line
@@ -81,8 +81,9 @@ struct vm_area_struct; 
int pci_mmap_page_range(struct pci_dev *pdev, struct vm_area_struct *vma,

			enum pci_mmap_state mmap_state, int write_combine);



/* Tell drivers/pci/proc.c that we have pci_mmap_page_range() */

/* Tell drivers/pci/proc.c that we have pci_mmap_page_range() and it does WC */

#define HAVE_PCI_MMAP		1

#define arch_can_pci_mmap_wc()	1



extern int pci_legacy_read(struct pci_bus *bus, loff_t port, u32 *val,

			   size_t count);

arch/x86/include/asm/pci.h

+2 −0
Original line number Diff line number Diff line
@@ -7,6 +7,7 @@ 
#include <linux/string.h>

#include <linux/scatterlist.h>

#include <asm/io.h>

#include <asm/pat.h>

#include <asm/x86_init.h>



#ifdef __KERNEL__
@@ -102,6 +103,7 @@ int pcibios_set_irq_routing(struct pci_dev *dev, int pin, int irq); 




#define HAVE_PCI_MMAP

#define arch_can_pci_mmap_wc()	pat_enabled()

extern int pci_mmap_page_range(struct pci_dev *dev, struct vm_area_struct *vma,

			       enum pci_mmap_state mmap_state,

			       int write_combine);

drivers/pci/pci-sysfs.c

+2 −2
Original line number Diff line number Diff line
@@ -1211,9 +1211,9 @@ static int pci_create_resource_files(struct pci_dev *pdev) 


		retval = pci_create_attr(pdev, i, 0);

		/* for prefetchable resources, create a WC mappable file */

		if (!retval && pdev->resource[i].flags & IORESOURCE_PREFETCH)

		if (!retval && arch_can_pci_mmap_wc() &&

		    pdev->resource[i].flags & IORESOURCE_PREFETCH)

			retval = pci_create_attr(pdev, i, 1);



		if (retval) {

			pci_remove_resource_files(pdev);

			return retval;