[PATCH v3 07/12] PCI: Set ports for discrete USB4 controllers appropriately

[Mario Limonciello]

Discrete USB4 controllers won't have ACPI nodes specifying which
PCIe or XHCI port they are linked with.

In order to set the removable attribute appropriately, use the
USB4 DVSEC extended capabability set on these root ports to determine
if they are located on a discrete USB4 controller.

Suggested-by: Mika Westerberg <mika.westerberg at linux.intel.com>
Link: https://usb.org/sites/default/files/USB4%20Specification%2020211116.zip
Signed-off-by: Mario Limonciello <mario.limonciello at amd.com>
---
 drivers/pci/probe.c     | 33 +++++++++++++++++++++++++++++++++
 include/linux/pci_ids.h |  2 ++
 2 files changed, 35 insertions(+)

diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index 67ca33188cba..1ed3e24db11e 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -25,6 +25,8 @@
 #define CARDBUS_LATENCY_TIMER	176	/* secondary latency timer */
 #define CARDBUS_RESERVE_BUSNR	3
 
+#define PCI_DVSEC_ID_USB4	0x23
+
 static struct resource busn_resource = {
 	.name	= "PCI busn",
 	.start	= 0,
@@ -1590,6 +1592,36 @@ static void set_pcie_untrusted(struct pci_dev *dev)
 		dev->untrusted = true;
 }
 
+static bool pci_is_discrete_usb4(struct pci_dev *dev)
+{
+	int dvsec_val = 0, pos;
+	u32 hdr;
+
+	/* USB4 spec says vendors can use either */
+	pos = pci_find_dvsec_capability(dev,
+					PCI_VENDOR_ID_INTEL,
+					PCI_DVSEC_ID_USB4);
+	if (pos) {
+		dvsec_val = 0x06;
+	} else {
+		pos = pci_find_dvsec_capability(dev,
+						PCI_VENDOR_ID_USB_IF,
+						PCI_DVSEC_ID_USB4);
+		if (pos)
+			dvsec_val = 0x01;
+	}
+	if (!dvsec_val)
+		return false;
+
+	pci_read_config_dword(dev, pos + PCI_DVSEC_HEADER2, &hdr);
+	if ((hdr & GENMASK(15, 0)) != dvsec_val)
+		return false;
+	/* this port is used for either NHI/PCIe tunnel/USB tunnel */
+	if (hdr & GENMASK(18, 16))
+		return true;
+	return false;
+}
+
 static void pci_set_removable(struct pci_dev *dev)
 {
 	struct pci_dev *parent = pci_upstream_bridge(dev);
@@ -1612,6 +1644,7 @@ static void pci_set_removable(struct pci_dev *dev)
 	if (vsec ||
 	    dev->class == PCI_CLASS_SERIAL_USB_USB4 ||
 	    pci_acpi_is_usb4(dev) ||
+	    pci_is_discrete_usb4(dev) ||
 	    (parent &&
 	    (parent->external_facing || dev_is_removable(&parent->dev))))
 		dev_set_removable(&dev->dev, DEVICE_REMOVABLE);
diff --git a/include/linux/pci_ids.h b/include/linux/pci_ids.h
index 61b161d914f0..271326e058b9 100644
--- a/include/linux/pci_ids.h
+++ b/include/linux/pci_ids.h
@@ -3097,4 +3097,6 @@
 
 #define PCI_VENDOR_ID_NCUBE		0x10ff
 
+#define PCI_VENDOR_ID_USB_IF		0x1EC0
+
 #endif /* _LINUX_PCI_IDS_H */
-- 
2.34.1