PCI: disable ASPM per ACPI FADT setting

The ACPI FADT table includes an ASPM control bit. If the bit is set, do
not enable ASPM since it may indicate that the platform doesn't actually
support the feature.

Tested-by: Jack Howarth <howarth@bromo.msbb.uc.edu>
Signed-off-by: Shaohua Li <shaohua.li@intel.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
diff --git a/drivers/pci/pcie/aspm.c b/drivers/pci/pcie/aspm.c
index f824955..759c51a 100644
--- a/drivers/pci/pcie/aspm.c
+++ b/drivers/pci/pcie/aspm.c
@@ -808,6 +808,11 @@
 
 __setup("pcie_noaspm", pcie_aspm_disable);
 
+void pcie_no_aspm(void)
+{
+	aspm_disabled = 1;
+}
+
 #ifdef CONFIG_ACPI
 #include <acpi/acpi_bus.h>
 #include <linux/pci-acpi.h>