[PATCH v3 05/12] PCI: Detect root port of internal USB4 devices by `usb4-host-interface`

[Mario Limonciello]

The root port used for PCIe tunneling should be marked as removable to
ensure that the entire chain is marked removable.

This can be done by looking for the device property specified in
the ACPI tables `usb4-host-interface`.

Suggested-by: Mika Westerberg <mika.westerberg at linux.intel.com>
Link: https://docs.microsoft.com/en-us/windows-hardware/drivers/pci/dsd-for-pcie-root-ports#mapping-native-protocols-pcie-displayport-tunneled-through-usb4-to-usb4-host-routers
Signed-off-by: Mario Limonciello <mario.limonciello at amd.com>
---
 drivers/pci/pci-acpi.c | 10 ++++++++++
 drivers/pci/pci.h      |  5 +++++
 drivers/pci/probe.c    |  1 +
 3 files changed, 16 insertions(+)

diff --git a/drivers/pci/pci-acpi.c b/drivers/pci/pci-acpi.c
index a42dbf448860..6368e5633b1b 100644
--- a/drivers/pci/pci-acpi.c
+++ b/drivers/pci/pci-acpi.c
@@ -1391,6 +1391,16 @@ void pci_acpi_cleanup(struct device *dev, struct acpi_device *adev)
 	}
 }
 
+bool pci_acpi_is_usb4(struct pci_dev *dev)
+{
+	struct acpi_device *adev = ACPI_COMPANION(&dev->dev);
+
+	if (!adev)
+		return false;
+	return fwnode_property_present(acpi_fwnode_handle(adev),
+				       "usb4-host-interface");
+}
+
 static struct fwnode_handle *(*pci_msi_get_fwnode_cb)(struct device *dev);
 
 /**
diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
index 3d60cabde1a1..359607c0542d 100644
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -695,6 +695,7 @@ void acpi_pci_refresh_power_state(struct pci_dev *dev);
 int acpi_pci_wakeup(struct pci_dev *dev, bool enable);
 bool acpi_pci_need_resume(struct pci_dev *dev);
 pci_power_t acpi_pci_choose_state(struct pci_dev *pdev);
+bool pci_acpi_is_usb4(struct pci_dev *dev);
 #else
 static inline int pci_dev_acpi_reset(struct pci_dev *dev, bool probe)
 {
@@ -734,6 +735,10 @@ static inline pci_power_t acpi_pci_choose_state(struct pci_dev *pdev)
 {
 	return PCI_POWER_ERROR;
 }
+static inline bool pci_acpi_is_usb4(struct pci_dev *dev)
+{
+	return false;
+}
 #endif
 
 #ifdef CONFIG_PCIEASPM
diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index e41656cdd8f0..2693211d31cf 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -1610,6 +1610,7 @@ static void pci_set_removable(struct pci_dev *dev)
 	 * exposed as "removable" to userspace.
 	 */
 	if (vsec ||
+	    pci_acpi_is_usb4(dev) ||
 	    (parent &&
 	    (parent->external_facing || dev_is_removable(&parent->dev))))
 		dev_set_removable(&dev->dev, DEVICE_REMOVABLE);
-- 
2.34.1