Each processor socket in a QPI system has a special PCI bus for the

"uncore" devices (such as the memory controller) in that socket.  Stop
hardcoding support for two busses, but instead start probing buses at
domain 0, bus 255 and walk down until a bus probe fails.  Also, do not probe
a bus if it has already been enumerated elsewhere (e.g. if ACPI ever
enumerates these buses in the future).

1 files changed, 45 insertions, 13 deletions

diff --git a/sys/x86/pci/qpi.c b/sys/x86/pci/qpi.c
index 169c1cd61021..131519530194 100644
--- a/sys/x86/pci/qpi.c
+++ b/sys/x86/pci/qpi.c
@@ -47,6 +47,7 @@ __FBSDID("$FreeBSD$");
 #include <machine/pci_cfgreg.h>
 #include <machine/specialreg.h>
 
+#include <dev/pci/pcireg.h>
 #include <dev/pci/pcivar.h>
 #include <dev/pci/pcib_private.h>
 #include "pcib_if.h"
@@ -84,31 +85,62 @@ qpi_probe(device_t dev)
 	return (BUS_PROBE_SPECIFIC);
 }
 
+/*
+ * Look for a PCI bus with the specified bus address.  If one is found,
+ * add a pcib device and return 0.  Otherwise, return an error code.
+ */
 static int
-qpi_attach(device_t dev)
+qpi_probe_pcib(device_t dev, int bus)
 {
 	struct qpi_device *qdev;
 	device_t child;
+	uint32_t devid;
 
 	/*
-	 * Add two Host-PCI bridge devices, one for PCI bus 254 and
-	 * one for PCI bus 255.
+	 * If a PCI bus already exists for this bus number, then
+	 * fail.
 	 */
-	child = BUS_ADD_CHILD(dev, 0, "pcib", -1);
-	if (child == NULL)
-		panic("%s: failed to add pci bus 254",
-		    device_get_nameunit(dev));
-	qdev = malloc(sizeof(struct qpi_device), M_QPI, M_WAITOK);
-	qdev->qd_pcibus = 254;
-	device_set_ivars(child, qdev);
+	if (pci_find_bsf(bus, 0, 0) != NULL)
+		return (EEXIST);
+
+	/*
+	 * Attempt to read the device id for device 0, function 0 on
+	 * the bus.  A value of 0xffffffff means that the bus is not
+	 * present.
+	 */
+	devid = pci_cfgregread(bus, 0, 0, PCIR_DEVVENDOR, 4);
+	if (devid == 0xffffffff)
+		return (ENOENT);
+
+	if ((devid & 0xffff) != 0x8086) {
+		device_printf(dev,
+		    "Device at pci%d.0.0 has non-Intel vendor 0x%x\n", bus,
+		    devid & 0xffff);
+		return (ENXIO);
+	}
 
 	child = BUS_ADD_CHILD(dev, 0, "pcib", -1);
 	if (child == NULL)
-		panic("%s: failed to add pci bus 255",
-		    device_get_nameunit(dev));
+		panic("%s: failed to add pci bus %d", device_get_nameunit(dev),
+		    bus);
 	qdev = malloc(sizeof(struct qpi_device), M_QPI, M_WAITOK);
-	qdev->qd_pcibus = 255;
+	qdev->qd_pcibus = bus;
 	device_set_ivars(child, qdev);
+	return (0);
+}
+
+static int
+qpi_attach(device_t dev)
+{
+	int bus;
+
+	/*
+	 * Each processor socket has a dedicated PCI bus counting down from
+	 * 255.  We keep probing buses until one fails.
+	 */
+	for (bus = 255;; bus--)
+		if (qpi_probe_pcib(dev, bus) != 0)
+			break;
 
 	return (bus_generic_attach(dev));
 }