powerpc/pci: Fix pcibios_setup_device() ordering

Move PCI device setup from pcibios_add_device() and pcibios_fixup_bus() to
pcibios_bus_add_device(). This ensures that platform-specific DMA and IOMMU
setup occurs after the device has been registered in sysfs, which is a
requirement for IOMMU group assignment to work

This fixes IOMMU group assignment for hotplugged devices on pseries, where
the existing behavior results in IOMMU assignment before registration.

Thanks to Lukas Wunner <lukas@wunner.de> for the suggestion.
Signed-off-by: Shawn Anastasio <shawn@anastas.io>
Tested-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Reviewed-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20191028085424.12006-2-oohall@gmail.com

arch/powerpc/kernel/pci-common.c

@@ -261,12 +261,6 @@ int pcibios_sriov_disable(struct pci_dev *pdev)
 
 #endif /* CONFIG_PCI_IOV */
 
-void pcibios_bus_add_device(struct pci_dev *pdev)
-{
-	if (ppc_md.pcibios_bus_add_device)
-		ppc_md.pcibios_bus_add_device(pdev);
-}
-
 static resource_size_t pcibios_io_size(const struct pci_controller *hose)
 {
 #ifdef CONFIG_PPC64
@@ -987,15 +981,17 @@ static void pcibios_setup_device(struct pci_dev *dev)
 		ppc_md.pci_irq_fixup(dev);
 }
 
-int pcibios_add_device(struct pci_dev *dev)
+void pcibios_bus_add_device(struct pci_dev *pdev)
 {
-	/*
-	 * We can only call pcibios_setup_device() after bus setup is complete,
-	 * since some of the platform specific DMA setup code depends on it.
-	 */
-	if (dev->bus->is_added)
-		pcibios_setup_device(dev);
+	/* Perform platform-specific device setup */
+	pcibios_setup_device(pdev);
+
+	if (ppc_md.pcibios_bus_add_device)
+		ppc_md.pcibios_bus_add_device(pdev);
+}
 
+int pcibios_add_device(struct pci_dev *dev)
+{
 #ifdef CONFIG_PCI_IOV
 	if (ppc_md.pcibios_fixup_sriov)
 		ppc_md.pcibios_fixup_sriov(dev);
@@ -1037,9 +1033,6 @@ void pcibios_fixup_bus(struct pci_bus *bus)
 
 	/* Now fixup the bus bus */
 	pcibios_setup_bus_self(bus);
-
-	/* Now fixup devices on that bus */
-	pcibios_setup_bus_devices(bus);
 }
 EXPORT_SYMBOL(pcibios_fixup_bus);