PCI: Add weak pcibios_window_alignment() interface

This patch implements a weak function to return the default I/O or memory
window alignment for a P2P bridge.  By default, I/O windows are aligned to
4KiB or 1KiB and memory windows are aligned to 4MiB.  Some platforms, e.g.,
powernv, have special alignment requirements and can override
pcibios_window_alignment().

[bhelgaas: changelog]
Signed-off-by: Gavin Shan <shangw@linux.vnet.ibm.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/include/linux/pci.h b/include/linux/pci.h
index b8667e0548e0..2c755243eef2 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -1064,6 +1064,8 @@ int pci_cfg_space_size_ext(struct pci_dev *dev);
 int pci_cfg_space_size(struct pci_dev *dev);
 unsigned char pci_bus_max_busnr(struct pci_bus *bus);
 void pci_setup_bridge(struct pci_bus *bus);
+resource_size_t pcibios_window_alignment(struct pci_bus *bus,
+                                         unsigned long type);
 
 #define PCI_VGA_STATE_CHANGE_BRIDGE (1 << 0)
 #define PCI_VGA_STATE_CHANGE_DECODES (1 << 1)