PCI: Add defines for bridge window indexing

include/linux/pci.h provides PCI_BRIDGE_{IO,MEM,PREF_MEM}_WINDOW defines,
however, they're based on the resource array indexing in the pci_dev
struct. The struct pci_bus also has pointers to those same resources but
they start from zeroth index.

Add PCI_BUS_BRIDGE_{IO,MEM,PREF_MEM}_WINDOW defines to get rid of literal
indexing.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Link: https://patch.msgid.link/20250829131113.36754-12-ilpo.jarvinen@linux.intel.com

Author: ij-intel

drivers/pci/pci.h

@@ -81,6 +81,10 @@ struct pcie_tlp_log;
 #define PCIE_MSG_CODE_DEASSERT_INTC	0x26
 #define PCIE_MSG_CODE_DEASSERT_INTD	0x27
 
+#define PCI_BUS_BRIDGE_IO_WINDOW	0
+#define PCI_BUS_BRIDGE_MEM_WINDOW	1
+#define PCI_BUS_BRIDGE_PREF_MEM_WINDOW	2
+
 extern const unsigned char pcie_link_speed[];
 extern bool pci_early_dump;
 

drivers/pci/probe.c

@@ -598,9 +598,13 @@ void pci_read_bridge_bases(struct pci_bus *child)
 	for (i = 0; i < PCI_BRIDGE_RESOURCE_NUM; i++)
 		child->resource[i] = &dev->resource[PCI_BRIDGE_RESOURCES+i];
 
-	pci_read_bridge_io(child->self, child->resource[0], false);
-	pci_read_bridge_mmio(child->self, child->resource[1], false);
-	pci_read_bridge_mmio_pref(child->self, child->resource[2], false);
+	pci_read_bridge_io(child->self,
+			   child->resource[PCI_BUS_BRIDGE_IO_WINDOW], false);
+	pci_read_bridge_mmio(child->self,
+			     child->resource[PCI_BUS_BRIDGE_MEM_WINDOW], false);
+	pci_read_bridge_mmio_pref(child->self,
+				  child->resource[PCI_BUS_BRIDGE_PREF_MEM_WINDOW],
+				  false);
 
 	if (!dev->transparent)
 		return;