i7core_edac: Properly discover the first QPI device

On Nehalem/Nehalem-EP/Westmere, the first QPI device is the last PCI bus.
The last bus is generally at 0x3f or 0xff, but there are also other systems
using different setups. For example, HP Z800 has 0x7f as the last bus.

This patch adds a logic to discover the last bus, dynamically detecting it
at runtime.

Acked-by: Doug Thompson <dougthompson@xmission.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/edac/i7core_edac.c

@@ -1233,18 +1233,37 @@ static void __init i7core_xeon_pci_fixup(struct pci_id_table *table)
 			for (i = 0; i < MAX_SOCKET_BUSES; i++)
 				pcibios_scan_specific_bus(255-i);
 		}
+		pci_dev_put(pdev);
 		table++;
 	}
 }
 
+static unsigned i7core_pci_lastbus(void)
+{
+	int last_bus = 0, bus;
+	struct pci_bus *b = NULL;
+
+	while ((b = pci_find_next_bus(b)) != NULL) {
+		bus = b->number;
+		debugf0("Found bus %d\n", bus);
+		if (bus > last_bus)
+			last_bus = bus;
+	}
+
+	debugf0("Last bus %d\n", last_bus);
+
+	return last_bus;
+}
+
 /*
  *	i7core_get_devices	Find and perform 'get' operation on the MCH's
  *			device/functions we want to reference for this driver
  *
  *			Need to 'get' device 16 func 1 and func 2
  */
 int i7core_get_onedevice(struct pci_dev **prev, int devno,
-			 struct pci_id_descr *dev_descr, unsigned n_devs)
+			 struct pci_id_descr *dev_descr, unsigned n_devs,
+			 unsigned last_bus)
 {
 	struct i7core_dev *i7core_dev;
 
@@ -1291,10 +1310,7 @@ int i7core_get_onedevice(struct pci_dev **prev, int devno,
 	}
 	bus = pdev->bus->number;
 
-	if (bus == 0x3f)
-		socket = 0;
-	else
-		socket = 255 - bus;
+	socket = last_bus - bus;
 
 	i7core_dev = get_i7core_dev(socket);
 	if (!i7core_dev) {
@@ -1358,17 +1374,21 @@ int i7core_get_onedevice(struct pci_dev **prev, int devno,
 
 static int i7core_get_devices(struct pci_id_table *table)
 {
-	int i, rc;
+	int i, rc, last_bus;
 	struct pci_dev *pdev = NULL;
 	struct pci_id_descr *dev_descr;
 
+	last_bus = i7core_pci_lastbus();
+
 	while (table && table->descr) {
 		dev_descr = table->descr;
 		for (i = 0; i < table->n_devs; i++) {
 			pdev = NULL;
 			do {
-				rc = i7core_get_onedevice(&pdev, i, &dev_descr[i],
-							  table->n_devs);
+				rc = i7core_get_onedevice(&pdev, i,
+							  &dev_descr[i],
+							  table->n_devs,
+							  last_bus);
 				if (rc < 0) {
 					if (i == 0) {
 						i = table->n_devs;