dm: pci: Add a function to get the controller for a bus

A PCI bus may be a bridge device where the controller is the bridge's
parent. Add a function to return the controller device, given a PCI device.

Signed-off-by: Simon Glass <sjg@chromium.org>
Acked-by: Stephen Warren <swarren@nvidia.com>
Tested-by: Stephen Warren <swarren@nvidia.com>

drivers/pci/pci-uclass.c

@@ -53,6 +53,14 @@ struct pci_controller *pci_bus_to_hose(int busnum)
 	return dev_get_uclass_priv(bus);
 }
 
+struct udevice *pci_get_controller(struct udevice *dev)
+{
+	while (device_is_on_pci_bus(dev))
+		dev = dev->parent;
+
+	return dev;
+}
+
 pci_dev_t pci_get_bdf(struct udevice *dev)
 {
 	struct pci_child_platdata *pplat = dev_get_parent_platdata(dev);

include/pci.h

@@ -1122,6 +1122,14 @@ ulong pci_conv_32_to_size(ulong value, uint offset, enum pci_size_t size);
 ulong pci_conv_size_to_32(ulong old, ulong value, uint offset,
 			  enum pci_size_t size);
 
+/**
+ * pci_get_controller() - obtain the controller to use for a bus
+ *
+ * @dev:	Device to check
+ * @return pointer to the controller device for this bus
+ */
+struct udevice *pci_get_controller(struct udevice *dev);
+
 /**
  * struct dm_pci_emul_ops - PCI device emulator operations
  */