+static void negotiate_os_control(struct acpi_pci_root *root, int *no_aspm,
+ int *clear_aspm)
+{
+ u32 support, control, requested;
+ acpi_status status;
+ struct acpi_device *device = root->device;
+ acpi_handle handle = device->handle;
+
+ /*
+ * All supported architectures that use ACPI have support for
+ * PCI domains, so we indicate this in _OSC support capabilities.
+ */
+ support = OSC_PCI_SEGMENT_GROUPS_SUPPORT;
+ if (pci_ext_cfg_avail())
+ support |= OSC_PCI_EXT_CONFIG_SUPPORT;
+ if (pcie_aspm_support_enabled())
+ support |= OSC_PCI_ASPM_SUPPORT | OSC_PCI_CLOCK_PM_SUPPORT;
+ if (pci_msi_enabled())
+ support |= OSC_PCI_MSI_SUPPORT;
+
+ decode_osc_support(root, "OS supports", support);
+ status = acpi_pci_osc_support(root, support);
+ if (ACPI_FAILURE(status)) {
+ dev_info(&device->dev, "_OSC failed (%s); disabling ASPM\n",
+ acpi_format_exception(status));
+ *no_aspm = 1;
+ return;
+ }
+
+ if (pcie_ports_disabled) {
+ dev_info(&device->dev, "PCIe port services disabled; not requesting _OSC control\n");
+ return;
+ }
+
+ if ((support & ACPI_PCIE_REQ_SUPPORT) != ACPI_PCIE_REQ_SUPPORT) {
+ decode_osc_support(root, "not requesting OS control; OS requires",
+ ACPI_PCIE_REQ_SUPPORT);
+ return;
+ }
+
+ control = OSC_PCI_EXPRESS_CAPABILITY_CONTROL
+ | OSC_PCI_EXPRESS_NATIVE_HP_CONTROL
+ | OSC_PCI_EXPRESS_PME_CONTROL;
+
+ if (pci_aer_available()) {
+ if (aer_acpi_firmware_first())
+ dev_info(&device->dev,
+ "PCIe AER handled by firmware\n");
+ else
+ control |= OSC_PCI_EXPRESS_AER_CONTROL;
+ }
+
+ requested = control;
+ status = acpi_pci_osc_control_set(handle, &control,
+ OSC_PCI_EXPRESS_CAPABILITY_CONTROL);
+ if (ACPI_SUCCESS(status)) {
+ decode_osc_control(root, "OS now controls", control);
+ if (acpi_gbl_FADT.boot_flags & ACPI_FADT_NO_ASPM) {
+ /*
+ * We have ASPM control, but the FADT indicates
+ * that it's unsupported. Clear it.
+ */
+ *clear_aspm = 1;
+ }
+ } else {
+ decode_osc_control(root, "OS requested", requested);
+ decode_osc_control(root, "platform willing to grant", control);
+ dev_info(&device->dev, "_OSC failed (%s); disabling ASPM\n",
+ acpi_format_exception(status));
+
+ /*
+ * We want to disable ASPM here, but aspm_disabled
+ * needs to remain in its state from boot so that we
+ * properly handle PCIe 1.1 devices. So we set this
+ * flag here, to defer the action until after the ACPI
+ * root scan.
+ */
+ *no_aspm = 1;
+ }
+}
+