[efi] Mark SNP devices as children of EFI PCI device

Re-open the EFI_PCI_IO_PROTOCOL specifying an Attributes value of
EFI_OPEN_PROTOCOL_BY_CHILD_CONTROLLER.  This causes the SNP devices to
be marked as children of the EFI PCI device (as shown in the "devtree"
command).

On at least one IBM blade system, this is required in order to have
the relevant drivers automatically attach to the SNP controller at
device creation time.

Signed-off-by: Michael Brown <mcb30@ipxe.org>

src/include/ipxe/efi/efi_pci.h

 	EFI_PCI_IO_PROTOCOL *pci_io;
 	/** Device path */
 	EFI_DEVICE_PATH_PROTOCOL *path;
+	/** EFI driver */
+	struct efi_driver *efidrv;
 };
 
 extern struct efi_pci_device * efipci_create ( struct efi_driver *efidrv,
 extern EFI_STATUS efipci_enable ( struct efi_pci_device *efipci );
 extern struct efi_pci_device * efipci_find_efi ( EFI_HANDLE device );
 extern struct efi_pci_device * efipci_find ( struct device *dev );
+extern EFI_STATUS efipci_child_add ( struct efi_pci_device *efipci,
+				     EFI_HANDLE device );
+extern void efipci_child_del ( struct efi_pci_device *efipci,
+			       EFI_HANDLE device );
 extern void efipci_destroy ( struct efi_driver *efidrv,
 			     struct efi_pci_device *efipci );
 

src/interface/efi/efi_pci.c

 	if ( ! efipci )
 		goto err_zalloc;
 	efipci->device = device;
+	efipci->efidrv = efidrv;
 
 	/* See if device is a PCI device */
 	if ( ( efirc = bs->OpenProtocol ( device,
 	return NULL;
 }
 
+/**
+ * Add EFI device as child of EFI PCI device
+ *
+ * @v efipci		EFI PCI device
+ * @v device		EFI child device
+ * @ret efirc		EFI status code
+ */
+EFI_STATUS efipci_child_add ( struct efi_pci_device *efipci,
+			      EFI_HANDLE device ) {
+	EFI_BOOT_SERVICES *bs = efi_systab->BootServices;
+	struct efi_driver *efidrv = efipci->efidrv;
+	union {
+		EFI_PCI_IO_PROTOCOL *pci_io;
+		void *interface;
+	} pci_io;
+	EFI_STATUS efirc;
+
+	/* Re-open the PCI_IO_PROTOCOL */
+	if ( ( efirc = bs->OpenProtocol ( efipci->device,
+					  &efi_pci_io_protocol_guid,
+					  &pci_io.interface,
+					  efidrv->driver.DriverBindingHandle,
+					  device,
+					  EFI_OPEN_PROTOCOL_BY_CHILD_CONTROLLER
+					  ) ) != 0 ) {
+		DBGC ( efipci, "EFIPCI " PCI_FMT " could not add child: %s\n",
+		       PCI_ARGS ( &efipci->pci ), efi_strerror ( efirc ) );
+		return efirc;
+	}
+
+	return 0;
+}
+
+/**
+ * Remove EFI device as child of PCI device
+ *
+ * @v efipci		EFI PCI device
+ * @v device		EFI child device
+ * @ret efirc		EFI status code
+ */
+void efipci_child_del ( struct efi_pci_device *efipci, EFI_HANDLE device ) {
+	EFI_BOOT_SERVICES *bs = efi_systab->BootServices;
+	struct efi_driver *efidrv = efipci->efidrv;
+
+	bs->CloseProtocol ( efipci->device, &efi_pci_io_protocol_guid,
+			    efidrv->driver.DriverBindingHandle, device );
+}
+
 /**
  * Destroy EFI PCI device
  *

src/interface/efi/efi_snp.c

 	struct list_head list;
 	/** The underlying iPXE network device */
 	struct net_device *netdev;
+	/** The underlying EFI PCI device */
+	struct efi_pci_device *efipci;
 	/** EFI device handle */
 	EFI_HANDLE handle;
 	/** The SNP structure itself */
 		goto err_alloc_snp;
 	}
 	snpdev->netdev = netdev_get ( netdev );
+	snpdev->efipci = efipci;
 
 	/* Sanity check */
 	if ( netdev->ll_protocol->ll_addr_len > sizeof ( EFI_MAC_ADDRESS ) ) {
 		goto err_install_protocol_interface;
 	}
 
+	/* Add as child of PCI device */
+	if ( ( efirc = efipci_child_add ( efipci, snpdev->handle ) ) != 0 ) {
+		DBGC ( snpdev, "SNPDEV %p could not become child of " PCI_FMT
+		       ": %s\n", snpdev, PCI_ARGS ( &efipci->pci ),
+		       efi_strerror ( efirc ) );
+		rc = EFIRC_TO_RC ( efirc );
+		goto err_efipci_child_add;
+	}
+
 	/* Add to list of SNP devices */
 	list_add ( &snpdev->list, &efi_snp_devices );
 
 	       snpdev, netdev->name, snpdev->handle );
 	return 0;
 
+	efipci_child_del ( efipci, snpdev->handle );
+ err_efipci_child_add:
 	bs->UninstallMultipleProtocolInterfaces (
 			snpdev->handle,
 			&efi_simple_network_protocol_guid, &snpdev->snp,
 	}
 
 	/* Uninstall the SNP */
+	efipci_child_del ( snpdev->efipci, snpdev->handle );
 	list_del ( &snpdev->list );
 	bs->UninstallMultipleProtocolInterfaces (
 			snpdev->handle,