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, 1 insertions, 11 deletions

diff --git a/include/linux/pci.h b/include/linux/pci.h
index 81a57b498f22..060af91bafcd 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -1909,24 +1909,14 @@ pci_alloc_irq_vectors(struct pci_dev *dev, unsigned int min_vecs,
 
 #include <asm/pci.h>
 
-/* These two functions provide almost identical functionality. Depending
- * on the architecture, one will be implemented as a wrapper around the
- * other (in drivers/pci/mmap.c).
- *
+/*
  * pci_mmap_resource_range() maps a specific BAR, and vm->vm_pgoff
  * is expected to be an offset within that region.
  *
- * pci_mmap_page_range() is the legacy architecture-specific interface,
- * which accepts a "user visible" resource address converted by
- * pci_resource_to_user(), as used in the legacy mmap() interface in
- * /proc/bus/pci/.
  */
 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 pci_mmap_page_range(struct pci_dev *pdev, int bar,
-			struct vm_area_struct *vma,
-			enum pci_mmap_state mmap_state, int write_combine);
 
 #ifndef arch_can_pci_mmap_wc
 #define arch_can_pci_mmap_wc()		0