powerpc/pci: Remove __pci_mmap_set_pgprot()

The powerpc-specific __pci_mmap_set_pgprot() does two things:

  1) Disables write combining for I/O port space mappings

     This only affects procfs mappings.  The pci_mmap_resource() sysfs path
     only requests write combining for resources with IORESOURCE_PREFETCH
     set, which doesn't include I/O resources.

     The only way to request write combining for I/O port space mappings
     was via the PCIIOC_WRITE_COMBINE ioctl and the proc_bus_pci_mmap()
     path, and we recently changed that path to ignore write combining for
     I/O, so this code in powerpc is no longer needed.

  2) Automatically enables write combining for mappings of prefetchable
     resources, even if not requested by the user

     Both procfs (via PCIIOC_MMAP_IS_MEM and PCIIOC_WRITE_COMBINE ioctls)
     and sysfs (via "resourceN_wc" files, which are created for resources
     with IORESOURCE_PREFETCH) provide ways for the user to map PCI memory
     space with write combining.

     Users that desire write combining should use one of those ways instead
     of relying on powerpc-specific behavior.

Remove the powerpc-specific __pci_mmap_set_pgprot().

The user-visible effect of this change is that powerpc users mapping
prefetchable PCI memory space via procfs without PCIIOC_WRITE_COMBINE or
via sysfs "resourceN" (not "resourceN_wc") will get regular uncacheable
mappings instead of the write combining mappings they used to get.

The new behavior matches the behavior on all other arches that support
write combining mapping.

[bhelgaas: changelog]
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

diff --git a/arch/powerpc/kernel/pci-common.c b/arch/powerpc/kernel/pci-common.c
index 0f7a60f1e9f6292ceb9f1ade5c67d2617d1aefb9..8c6beb0229fe5a24688cd8b5c78861a3b0f2fb67 100644 (file)
--- a/arch/powerpc/kernel/pci-common.c
+++ b/arch/powerpc/kernel/pci-common.c
@@ -355,36 +355,6 @@ static struct resource *__pci_mmap_make_offset(struct pci_dev *dev,
        return NULL;
 }
 
-/*
- * Set vm_page_prot of VMA, as appropriate for this architecture, for a pci
- * device mapping.
- */
-static pgprot_t __pci_mmap_set_pgprot(struct pci_dev *dev, struct resource *rp,
-                                     pgprot_t protection,
-                                     enum pci_mmap_state mmap_state,
-                                     int write_combine)
-{
-
-       /* Write combine is always 0 on non-memory space mappings. On
-        * memory space, if the user didn't pass 1, we check for a
-        * "prefetchable" resource. This is a bit hackish, but we use
-        * this to workaround the inability of /sysfs to provide a write
-        * combine bit
-        */
-       if (mmap_state != pci_mmap_mem)
-               write_combine = 0;
-       else if (write_combine == 0) {
-               if (rp->flags & IORESOURCE_PREFETCH)
-                       write_combine = 1;
-       }
-
-       /* XXX would be nice to have a way to ask for write-through */
-       if (write_combine)
-               return pgprot_noncached_wc(protection);
-       else
-               return pgprot_noncached(protection);
-}
-
 /*
  * This one is used by /dev/mem and fbdev who have no clue about the
  * PCI device, it tries to find the PCI device first and calls the
@@ -458,9 +428,10 @@ int pci_mmap_page_range(struct pci_dev *dev, struct vm_area_struct *vma,
                return -EINVAL;
 
        vma->vm_pgoff = offset >> PAGE_SHIFT;
-       vma->vm_page_prot = __pci_mmap_set_pgprot(dev, rp,
-                                                 vma->vm_page_prot,
-                                                 mmap_state, write_combine);
+       if (write_combine)
+               vma->vm_page_prot = pgprot_noncached_wc(vma->vm_page_prot);
+       else
+               vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
 
        ret = remap_pfn_range(vma, vma->vm_start, vma->vm_pgoff,
                               vma->vm_end - vma->vm_start, vma->vm_page_prot);