[PATCH v3 1/3] PCI: Preserve the initial bus number in pci_bus

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

Bridges that need bus reassignment are scanned in two passes. Save
the firmware secondary bus number during the first pass, before the
bridge is disabled, and carry it to the bus created in the second
pass. Drivers can then match firmware records against the bus number
from before PCI bus renumbering.

The initial number belongs to the bus, so consumers can use the
pci_bus value directly without copying it into every pci_dev.

Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
---
 drivers/pci/probe.c | 9 +++++++++
 include/linux/pci.h | 2 ++
 2 files changed, 11 insertions(+)

diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index 27008e2ea5afc..9950a9dd1db1f 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -1012,6 +1012,7 @@ static int pci_register_host_bridge(struct pci_host_bridge *bridge)
 	bus->sysdata = bridge->sysdata;
 	bus->ops = bridge->ops;
 	bus->number = bus->busn_res.start = bridge->busnr;
+	bus->number_initial = bus->number;
 #ifdef CONFIG_PCI_DOMAINS_GENERIC
 	if (bridge->domain_nr == PCI_DOMAIN_NR_NOT_SET)
 		bus->domain_nr = pci_bus_find_domain_nr(bus, parent);
@@ -1232,6 +1233,7 @@ static struct pci_bus *pci_alloc_child_bus(struct pci_bus *parent,
 
 	/* Set up the primary, secondary and subordinate bus numbers */
 	child->number = child->busn_res.start = busnr;
+	child->number_initial = busnr;
 	child->primary = parent->busn_res.start;
 	child->busn_res.end = 0xff;
 
@@ -1470,6 +1472,7 @@ static int pci_scan_bridge_extend(struct pci_bus *bus, struct pci_dev *dev,
 			child = pci_add_new_bus(bus, dev, secondary);
 			if (!child)
 				goto out;
+			child->number_initial = secondary;
 			child->primary = primary;
 			pci_bus_insert_busn_res(child, secondary, subordinate);
 			child->bridge_ctl = bctl;
@@ -1491,6 +1494,8 @@ static int pci_scan_bridge_extend(struct pci_bus *bus, struct pci_dev *dev,
 		 * do in the second pass.
 		 */
 		if (!pass) {
+			if (!dev->secondary_busnr)
+				dev->secondary_busnr = secondary;
 			if (pcibios_assign_all_busses() || broken)
 
 				/*
@@ -1529,6 +1534,10 @@ static int pci_scan_bridge_extend(struct pci_bus *bus, struct pci_dev *dev,
 			pci_bus_insert_busn_res(child, next_busnr,
 						bus->busn_res.end);
 		}
+		if (dev->secondary_busnr) {
+			child->number_initial = dev->secondary_busnr;
+			dev->secondary_busnr = 0;
+		}
 		max++;
 		if (available_buses)
 			available_buses--;
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 5ffcf5ce8c966..75a5fd2374acb 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		secondary_busnr;	/* Original secondary bus number */
 	unsigned short	vendor;
 	unsigned short	device;
 	unsigned short	subsystem_vendor;
@@ -724,6 +725,7 @@ struct pci_bus {
 	struct proc_dir_entry *procdir;	/* Directory entry in /proc/bus/pci */
 
 	unsigned char	number;		/* Bus number */
+	unsigned char	number_initial;	/* Bus number before reassignment */
 	unsigned char	primary;	/* Number of primary bridge */
 	unsigned char	max_bus_speed;	/* enum pci_bus_speed */
 	unsigned char	cur_bus_speed;	/* enum pci_bus_speed */

-- 
2.43.0