PCI: Add pci_ops.{add,remove}_bus() callbacks

Add pci_ops.{add,remove}_bus() callbacks, which will be called on every
newly created bus and when a bus is being removed, respectively.  This can
be used by drivers to implement driver-specific initialization and teardown
of the bus, in addition to the architecture-specifics implemented by the
pcibios_add_bus() and the pcibios_remove_bus() functions.
Signed-off-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

drivers/pci/probe.c

@@ -758,6 +758,12 @@ static struct pci_bus *pci_alloc_child_bus(struct pci_bus *parent,
 
 	pcibios_add_bus(child);
 
+	if (child->ops->add_bus) {
+		ret = child->ops->add_bus(child);
+		if (WARN_ON(ret < 0))
+			dev_err(&child->dev, "failed to add bus: %d\n", ret);
+	}
+
 	/* Create legacy_io and legacy_mem files for this bus */
 	pci_create_legacy_files(child);
 

drivers/pci/remove.c

@@ -54,6 +54,10 @@ void pci_remove_bus(struct pci_bus *bus)
 	pci_bus_release_busn_res(bus);
 	up_write(&pci_bus_sem);
 	pci_remove_legacy_files(bus);
+
+	if (bus->ops->remove_bus)
+		bus->ops->remove_bus(bus);
+
 	pcibios_remove_bus(bus);
 	device_unregister(&bus->dev);
 }

include/linux/pci.h

@@ -578,6 +578,8 @@ static inline int pcibios_err_to_errno(int err)
 /* Low-level architecture-dependent routines */
 
 struct pci_ops {
+	int (*add_bus)(struct pci_bus *bus);
+	void (*remove_bus)(struct pci_bus *bus);
 	void __iomem *(*map_bus)(struct pci_bus *bus, unsigned int devfn, int where);
 	int (*read)(struct pci_bus *bus, unsigned int devfn, int where, int size, u32 *val);
 	int (*write)(struct pci_bus *bus, unsigned int devfn, int where, int size, u32 val);