PCI: Add support for unbinding the generic PCI host controller

Add support for unbinding the generic PCI host controller.  This is
particularly useful when working in virtual environments where the
controller may come and go, but possibly not only there.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
CC: Will Deacon <will.deacon@arm.com>
CC: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>

drivers/pci/host/pci-host-common.c

@@ -101,5 +101,18 @@ int pci_host_common_probe(struct platform_device *pdev,
 		return ret;
 	}
 
+	platform_set_drvdata(pdev, bridge->bus);
+	return 0;
+}
+
+int pci_host_common_remove(struct platform_device *pdev)
+{
+	struct pci_bus *bus = platform_get_drvdata(pdev);
+
+	pci_lock_rescan_remove();
+	pci_stop_root_bus(bus);
+	pci_remove_root_bus(bus);
+	pci_unlock_rescan_remove();
+
 	return 0;
 }

drivers/pci/host/pci-host-generic.c

@@ -95,5 +95,6 @@ static struct platform_driver gen_pci_driver = {
 		.suppress_bind_attrs = true,
 	},
 	.probe = gen_pci_probe,
+	.remove = pci_host_common_remove,
 };
 builtin_platform_driver(gen_pci_driver);

include/linux/pci-ecam.h

@@ -62,5 +62,6 @@ extern struct pci_ecam_ops xgene_v2_pcie_ecam_ops; /* APM X-Gene PCIe v2.x */
 /* for DT-based PCI controllers that support ECAM */
 int pci_host_common_probe(struct platform_device *pdev,
 			  struct pci_ecam_ops *ops);
+int pci_host_common_remove(struct platform_device *pdev);
 #endif
 #endif