PCI: Remove pci_mmap_page_range() wrapper

The ARCH_GENERIC_PCI_MMAP_RESOURCE symbol came up in a recent discussion,
and I noticed that this was left behind by an unfinished cleanup from 2017.

The only architecture that still relies on providing its own
pci_mmap_page_range() helper instead of using the generic
pci_mmap_resource_range() is sparc. Presumably the reasons for this have
not changed, but at least this can be simplified by converting sparc to use
the same interface as the others.

The only difference between the two is the device-specific offset that gets
added to or subtracted from vma->vm_pgoff.

Change the only caller of pci_mmap_page_range() in common code to subtract
this offset and call the modern interface, while adding it back in the
sparc implementation to preserve the existing behavior.

This removes the complexities of the dual interfaces from the common code,
and keeps it all specific to the sparc architecture code. According to
David Miller, the sparc code lets user space poke into the VGA I/O port
registers by mmapping the I/O space of the parent bridge device, which is
something that the generic pci_mmap_resource_range() code apparently does
not.

Link: https://lore.kernel.org/lkml/1519887203.622.3.camel@infradead.org/t/
Link: https://lore.kernel.org/lkml/20220714214657.2402250-3-shorne@gmail.com/
Link: https://lore.kernel.org/r/20220715153617.3393420-1-arnd@kernel.org
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: David S. Miller <davem@davemloft.net>
Cc: Stafford Horne <shorne@gmail.com>

1 files changed, 9 insertions, 4 deletions

diff --git a/arch/sparc/kernel/pci.c b/arch/sparc/kernel/pci.c
index 31b0c1983286..f580db840bf7 100644
--- a/arch/sparc/kernel/pci.c
+++ b/arch/sparc/kernel/pci.c
@@ -876,17 +876,22 @@ static void __pci_mmap_set_pgprot(struct pci_dev *dev, struct vm_area_struct *vm
 
 /* Perform the actual remap of the pages for a PCI device mapping, as appropriate
  * for this architecture.  The region in the process to map is described by vm_start
- * and vm_end members of VMA, the base physical address is found in vm_pgoff.
+ * and vm_end members of VMA, the BAR relative address is found in vm_pgoff.
  * The pci device structure is provided so that architectures may make mapping
  * decisions on a per-device or per-bus basis.
  *
  * Returns a negative error code on failure, zero on success.
  */
-int pci_mmap_page_range(struct pci_dev *dev, int bar,
-			struct vm_area_struct *vma,
-			enum pci_mmap_state mmap_state, int write_combine)
+int pci_mmap_resource_range(struct pci_dev *dev, int bar,
+			    struct vm_area_struct *vma,
+			    enum pci_mmap_state mmap_state, int write_combine)
 {
 	int ret;
+	resource_size_t start, end;
+
+	/* convert per-BAR address to PCI bus address */
+	pci_resource_to_user(dev, bar, &dev->resource[bar], &start, &end);
+	vma->vm_pgoff += start >> PAGE_SHIFT;
 
 	ret = __pci_mmap_make_offset(dev, vma, mmap_state);
 	if (ret < 0)