PCI: break out primary/secondary/subordinate for readability

No functional change; just add names for the primary/secondary/subordinate
bus numbers read from config space rather than repeatedly masking/shifting.
Signed-off-by: Bjorn Helgaas <bjorn.helgaas@hp.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>

drivers/pci/probe.c

@@ -673,16 +673,20 @@ int __devinit pci_scan_bridge(struct pci_bus *bus, struct pci_dev *dev, int max,
 	int is_cardbus = (dev->hdr_type == PCI_HEADER_TYPE_CARDBUS);
 	u32 buses, i, j = 0;
 	u16 bctl;
+	u8 primary, secondary, subordinate;
 	int broken = 0;
 
 	pci_read_config_dword(dev, PCI_PRIMARY_BUS, &buses);
+	primary = buses & 0xFF;
+	secondary = (buses >> 8) & 0xFF;
+	subordinate = (buses >> 16) & 0xFF;
 
-	dev_dbg(&dev->dev, "scanning behind bridge, config %06x, pass %d\n",
-		buses & 0xffffff, pass);
+	dev_dbg(&dev->dev, "scanning [bus %02x-%02x] behind bridge, pass %d\n",
+		secondary, subordinate, pass);
 
 	/* Check if setup is sensible at all */
 	if (!pass &&
-	    ((buses & 0xff) != bus->number || ((buses >> 8) & 0xff) <= bus->number)) {
+	    (primary != bus->number || secondary <= bus->number)) {
 		dev_dbg(&dev->dev, "bus configuration invalid, reconfiguring\n");
 		broken = 1;
 	}
@@ -693,15 +697,15 @@ int __devinit pci_scan_bridge(struct pci_bus *bus, struct pci_dev *dev, int max,
 	pci_write_config_word(dev, PCI_BRIDGE_CONTROL,
 			      bctl & ~PCI_BRIDGE_CTL_MASTER_ABORT);
 
-	if ((buses & 0xffff00) && !pcibios_assign_all_busses() && !is_cardbus && !broken) {
-		unsigned int cmax, busnr;
+	if ((secondary || subordinate) && !pcibios_assign_all_busses() &&
+	    !is_cardbus && !broken) {
+		unsigned int cmax;
 		/*
 		 * Bus already configured by firmware, process it in the first
 		 * pass and just note the configuration.
 		 */
 		if (pass)
 			goto out;
-		busnr = (buses >> 8) & 0xFF;
 
 		/*
 		 * If we already got to this bus through a different bridge,
@@ -710,13 +714,13 @@ int __devinit pci_scan_bridge(struct pci_bus *bus, struct pci_dev *dev, int max,
 		 * However, we continue to descend down the hierarchy and
 		 * scan remaining child buses.
 		 */
-		child = pci_find_bus(pci_domain_nr(bus), busnr);
+		child = pci_find_bus(pci_domain_nr(bus), secondary);
 		if (!child) {
-			child = pci_add_new_bus(bus, dev, busnr);
+			child = pci_add_new_bus(bus, dev, secondary);
 			if (!child)
 				goto out;
-			child->primary = buses & 0xFF;
-			child->subordinate = (buses >> 16) & 0xFF;
+			child->primary = primary;
+			child->subordinate = subordinate;
 			child->bridge_ctl = bctl;
 		}