[PATCH v10 3/3] thunderbolt: Add device links for Apple systems with Ice Lake

[Mika Westerberg <mika.westerberg@linux.intel.com>]

From: Atharva Tiwari <atharvatiwarilinuxdev@gmail.com>

Ice Lake Thunderbolt NHI that are on some Macs. The NHI and its
associated PCIe Root Ports all sit directly on the Root Complex with no
upstream port. Identify the tunneled PCIe Root Ports by their PCI IDs
and create device links back to the NHI so that PCIe tunnels can be
re-established after sleep.

Co-developed-by: Andre Eikmeyer <andre@negmaster.com>
Signed-off-by: Andre Eikmeyer <andre@negmaster.com>
Signed-off-by: Atharva Tiwari <atharvatiwarilinuxdev@gmail.com>
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
---
 drivers/thunderbolt/pci.c | 35 +++++++++++++++++++++++++++++++++++
 1 file changed, 35 insertions(+)

diff --git a/drivers/thunderbolt/pci.c b/drivers/thunderbolt/pci.c
index 996a8ab3cfb7..e40d4d6af071 100644
--- a/drivers/thunderbolt/pci.c
+++ b/drivers/thunderbolt/pci.c
@@ -521,6 +521,40 @@ static int icl_nhi_resume(struct tb_nhi *nhi)
 	return 0;
 }
 
+static bool icl_nhi_add_links(struct tb_nhi *nhi)
+{
+	struct pci_dev *nhi_pdev = to_pci_dev(nhi->dev);
+	struct pci_bus *bus = nhi_pdev->bus;
+	struct pci_dev *pdev;
+	bool ret;
+
+	if (!x86_apple_machine)
+		return false;
+
+	/*
+	 * On integrated controllers the tunneled PCIe root ports are
+	 * directly under the host bridge.
+	 */
+	if (!pci_is_root_bus(bus))
+		return false;
+
+	ret = false;
+	for_each_pci_bridge(pdev, bus) {
+		switch (nhi_pdev->device) {
+		case PCI_DEVICE_ID_INTEL_ICL_NHI0:
+			if (pdev->device == 0x8a1d || pdev->device == 0x8a1f)
+				ret |= add_link(nhi, pdev);
+			break;
+		case PCI_DEVICE_ID_INTEL_ICL_NHI1:
+			if (pdev->device == 0x8a21 || pdev->device == 0x8a23)
+				ret |= add_link(nhi, pdev);
+			break;
+		}
+	}
+
+	return ret;
+}
+
 static void icl_nhi_shutdown(struct tb_nhi *nhi)
 {
 	nhi_pci_release_irq(nhi);
@@ -530,6 +564,7 @@ static void icl_nhi_shutdown(struct tb_nhi *nhi)
 
 static const struct tb_nhi_ops icl_nhi_ops = {
 	.init = icl_nhi_resume,
+	.add_links = icl_nhi_add_links,
 	.suspend_noirq = icl_nhi_suspend_noirq,
 	.resume_noirq = icl_nhi_resume,
 	.runtime_suspend = icl_nhi_suspend,
-- 
2.50.1