We're about to allow runtime PM on Thunderbolt ports in
pci_bridge_d3_possible() and unblock runtime PM for Thunderbolt host
hotplug ports in pci_dev_check_d3cold(). In both cases we need to
uniquely identify if a PCI device belongs to a Thunderbolt controller.
We also have the need to detect presence of a Thunderbolt controller in
drivers/platform/x86/apple-gmux.c because dual GPU MacBook Pros cannot
switch external DP/HDMI ports between GPUs if they have Thunderbolt.
Furthermore, in multiple places in the DRM subsystem we need to detect
whether a GPU is on-board or attached with Thunderbolt. As an example,
Thunderbolt-attached GPUs shall not be registered with vga_switcheroo.
Intel uses a Vendor-Specific Extended Capability (VSEC) with ID 0x1234
on devices belonging to a Thunderbolt controller which allows us to
recognize them.
Detect presence of this VSEC on device probe and cache it in a newly
added is_thunderbolt bit in struct pci_dev which can then be queried by
pci_bridge_d3_possible(), pci_dev_check_d3cold(), apple-gmux and others.
Cc: Andreas Noever <andreas.noever@xxxxxxxxx>
Cc: Tomas Winkler <tomas.winkler@xxxxxxxxx>
Cc: Amir Levy <amir.jer.levy@xxxxxxxxx>
Signed-off-by: Lukas Wunner <lukas@xxxxxxxxx>
---
drivers/pci/pci.h | 2 ++
drivers/pci/probe.c | 34 ++++++++++++++++++++++++++++++++++
include/linux/pci.h | 1 +
3 files changed, 37 insertions(+)
diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
index cb17db242f30..45c2b8144911 100644
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -3,6 +3,8 @@
#define PCI_FIND_CAP_TTL 48
+#define PCI_VSEC_ID_INTEL_TBT 0x1234 /* Thunderbolt */
+
extern const unsigned char pcie_link_speed[];
bool pcie_cap_has_lnkctl(const struct pci_dev *dev);
diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index e164b5c9f0f0..891a8fa1f9f6 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -1206,6 +1206,37 @@ void set_pcie_hotplug_bridge(struct pci_dev *pdev)
pdev->is_hotplug_bridge = 1;
}
+static void set_pcie_vendor_specific(struct pci_dev *dev)
+{
+ int vsec = 0;
+ u32 header;
+
+ while ((vsec = pci_find_next_ext_capability(dev, vsec,
+ PCI_EXT_CAP_ID_VNDR))) {
+ pci_read_config_dword(dev, vsec + PCI_VNDR_HEADER, &header);
+
+ /* Is the device part of a Thunderbolt controller? */
+ if (dev->vendor == PCI_VENDOR_ID_INTEL &&
+ PCI_VNDR_HEADER_ID(header) == PCI_VSEC_ID_INTEL_TBT)
+ dev->is_thunderbolt = 1;
+ }
+
+ /*
+ * Is the device attached with Thunderbolt? Walk upwards and check for
+ * each encountered bridge if it's part of a Thunderbolt controller.
+ * Reaching the host bridge means dev is soldered to the mainboard.
+ */
+ if (!dev->is_thunderbolt) {
+ struct pci_dev *parent = dev;
+
+ while ((parent = pci_upstream_bridge(parent)))
+ if (parent->is_thunderbolt) {
+ dev->is_thunderbolt = 1;
+ break;
+ }
+ }
+}
+
/**
* pci_ext_cfg_is_aliased - is ext config space just an alias of std config?
* @dev: PCI device
@@ -1358,6 +1389,9 @@ int pci_setup_device(struct pci_dev *dev)
/* need to have dev->class ready */
dev->cfg_size = pci_cfg_space_size(dev);
+ /* need to have dev->cfg_size ready */
+ set_pcie_vendor_specific(dev);
+
/* "Unknown power state" */
dev->current_state = PCI_UNKNOWN;
diff --git a/include/linux/pci.h b/include/linux/pci.h
index e2d1a124216a..3c775e8498f1 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -358,6 +358,7 @@ struct pci_dev {
unsigned int is_virtfn:1;
unsigned int reset_fn:1;
unsigned int is_hotplug_bridge:1;
+ unsigned int is_thunderbolt:1; /* part of Thunderbolt daisy chain */
unsigned int __aer_firmware_first_valid:1;
unsigned int __aer_firmware_first:1;
unsigned int broken_intx_masking:1;
--
2.11.0
--
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