1 files changed, 117 insertions, 0 deletions
diff --git a/drivers/thunderbolt/acpi.c b/drivers/thunderbolt/acpi.c
new file mode 100644
index 000000000000..a5f988a9f948
--- /dev/null
+++ b/drivers/thunderbolt/acpi.c
@@ -0,0 +1,117 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * ACPI support
+ *
+ * Copyright (C) 2020, Intel Corporation
+ * Author: Mika Westerberg <mika.westerberg@linux.intel.com>
+ */
+
+#include <linux/acpi.h>
+
+#include "tb.h"
+
+static acpi_status tb_acpi_add_link(acpi_handle handle, u32 level, void *data,
+				    void **return_value)
+{
+	struct fwnode_reference_args args;
+	struct fwnode_handle *fwnode;
+	struct tb_nhi *nhi = data;
+	struct acpi_device *adev;
+	struct pci_dev *pdev;
+	struct device *dev;
+	int ret;
+
+	if (acpi_bus_get_device(handle, &adev))
+		return AE_OK;
+
+	fwnode = acpi_fwnode_handle(adev);
+	ret = fwnode_property_get_reference_args(fwnode, "usb4-host-interface",
+						 NULL, 0, 0, &args);
+	if (ret)
+		return AE_OK;
+
+	/* It needs to reference this NHI */
+	if (nhi->pdev->dev.fwnode != args.fwnode)
+		goto out_put;
+
+	/*
+	 * Try to find physical device walking upwards to the hierarcy.
+	 * We need to do this because the xHCI driver might not yet be
+	 * bound so the USB3 SuperSpeed ports are not yet created.
+	 */
+	dev = acpi_get_first_physical_node(adev);
+	while (!dev) {
+		adev = adev->parent;
+		if (!adev)
+			break;
+		dev = acpi_get_first_physical_node(adev);
+	}
+
+	if (!dev)
+		goto out_put;
+
+	/*
+	 * Check that the device is PCIe. This is because USB3
+	 * SuperSpeed ports have this property and they are not power
+	 * managed with the xHCI and the SuperSpeed hub so we create the
+	 * link from xHCI instead.
+	 */
+	while (!dev_is_pci(dev))
+		dev = dev->parent;
+
+	if (!dev)
+		goto out_put;
+
+	/*
+	 * Check that this actually matches the type of device we
+	 * expect. It should either be xHCI or PCIe root/downstream
+	 * port.
+	 */
+	pdev = to_pci_dev(dev);
+	if (pdev->class == PCI_CLASS_SERIAL_USB_XHCI ||
+	    (pci_is_pcie(pdev) &&
+		(pci_pcie_type(pdev) == PCI_EXP_TYPE_ROOT_PORT ||
+		 pci_pcie_type(pdev) == PCI_EXP_TYPE_DOWNSTREAM))) {
+		const struct device_link *link;
+
+		link = device_link_add(&pdev->dev, &nhi->pdev->dev,
+				       DL_FLAG_AUTOREMOVE_SUPPLIER |
+				       DL_FLAG_PM_RUNTIME);
+		if (link) {
+			dev_dbg(&nhi->pdev->dev, "created link from %s\n",
+				dev_name(&pdev->dev));
+		} else {
+			dev_warn(&nhi->pdev->dev, "device link creation from %s failed\n",
+				 dev_name(&pdev->dev));
+		}
+	}
+
+out_put:
+	fwnode_handle_put(args.fwnode);
+	return AE_OK;
+}
+
+/**
+ * tb_acpi_add_links() - Add device links based on ACPI description
+ * @nhi: Pointer to NHI
+ *
+ * Goes over ACPI namespace finding tunneled ports that reference to
+ * @nhi ACPI node. For each reference a device link is added. The link
+ * is automatically removed by the driver core.
+ */
+void tb_acpi_add_links(struct tb_nhi *nhi)
+{
+	acpi_status status;
+
+	if (!has_acpi_companion(&nhi->pdev->dev))
+		return;
+
+	/*
+	 * Find all devices that have usb4-host-controller interface
+	 * property that references to this NHI.
+	 */
+	status = acpi_walk_namespace(ACPI_TYPE_DEVICE, ACPI_ROOT_OBJECT, 32,
+				     tb_acpi_add_link, NULL, nhi, NULL);
+	if (ACPI_FAILURE(status))
+		dev_warn(&nhi->pdev->dev, "failed to enumerate tunneled ports\n");
+}