[pci] Drag in PCI settings mechanism only when PCI support is present

Allow for the existence of platforms with no PCI bus by including the
PCI settings mechanism only if PCI bus support is included.

Signed-off-by: Michael Brown <mcb30@ipxe.org>
diff --git a/src/config/config.c b/src/config/config.c
index 4cfa5dd..254bff9 100644
--- a/src/config/config.c
+++ b/src/config/config.c
@@ -352,9 +352,6 @@
 /*
  * Drag in relevant settings sources
  */
-#ifdef PCI_SETTINGS
-REQUIRE_OBJECT ( pci_settings );
-#endif
 #ifdef VMWARE_SETTINGS
 REQUIRE_OBJECT ( guestinfo );
 #endif
diff --git a/src/config/config_pci.c b/src/config/config_pci.c
new file mode 100644
index 0000000..cb8df71
--- /dev/null
+++ b/src/config/config_pci.c
@@ -0,0 +1,36 @@
+/*
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+ * 02110-1301, USA.
+ *
+ * You can also choose to distribute this program under the terms of
+ * the Unmodified Binary Distribution Licence (as given in the file
+ * COPYING.UBDL), provided that you have satisfied its requirements.
+ */
+
+FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
+
+#include <config/settings.h>
+
+/** @file
+ *
+ * PCI configuration options
+ *
+ */
+
+PROVIDE_REQUIRING_SYMBOL();
+
+#ifdef PCI_SETTINGS
+REQUIRE_OBJECT ( pci_settings );
+#endif
diff --git a/src/drivers/bus/pci.c b/src/drivers/bus/pci.c
index 05c9a5c..60740ac 100644
--- a/src/drivers/bus/pci.c
+++ b/src/drivers/bus/pci.c
@@ -438,3 +438,9 @@
 	.dev = { .name = "PCI" },
 	.driver = &pci_root_driver,
 };
+
+/* Drag in objects via pcibus_probe() */
+REQUIRING_SYMBOL ( pcibus_probe );
+
+/* Drag in PCI configuration */
+REQUIRE_OBJECT ( config_pci );