[PATCH 1/2] PCI: Preserve the initial bus number in pci_dev

[Mario Limonciello <mario.limonciello@amd.com>]

PCI bus numbers can be reassigned after device discovery, for example
during resource reallocation. Preserve the number seen at allocation
time so drivers can match devices using firmware-visible bus numbers.

Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
---
 drivers/pci/probe.c | 1 +
 include/linux/pci.h | 1 +
 2 files changed, 2 insertions(+)

diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index 27008e2ea5afc..580b288d5c64f 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -2508,6 +2508,7 @@ struct pci_dev *pci_alloc_dev(struct pci_bus *bus)
 	INIT_LIST_HEAD(&dev->bus_list);
 	dev->dev.type = &pci_dev_type;
 	dev->bus = pci_bus_get(bus);
+	dev->initial_bus_number = bus->number;
 	dev->driver_exclusive_resource = (struct resource) {
 		.name = "PCI Exclusive",
 		.start = 0,
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 5ffcf5ce8c966..dae68b28ce051 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -363,6 +363,7 @@ struct pci_dev {
 	struct pci_slot	*slot;		/* Physical slot this device is in */
 
 	unsigned int	devfn;		/* Encoded device & function index */
+	u8		initial_bus_number;	/* Bus number when device was discovered */
 	unsigned short	vendor;
 	unsigned short	device;
 	unsigned short	subsystem_vendor;

-- 
2.43.0