[efi] Include a copy of the device path within struct efi_device

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

src/include/ipxe/efi/efi_driver.h

 	struct device dev;
 	/** EFI device handle */
 	EFI_HANDLE device;
+	/** EFI device path copy */
+	EFI_DEVICE_PATH_PROTOCOL *path;
 	/** Driver for this device */
 	struct efi_driver *driver;
 	/** Driver-private data */

src/interface/efi/efi_driver.c

 #include <ipxe/efi/Protocol/ComponentName2.h>
 #include <ipxe/efi/Protocol/DevicePath.h>
 #include <ipxe/efi/efi_strings.h>
+#include <ipxe/efi/efi_utils.h>
 #include <ipxe/efi/efi_driver.h>
 
 /** @file
 static EFI_STATUS EFIAPI
 efi_driver_start ( EFI_DRIVER_BINDING_PROTOCOL *driver __unused,
 		   EFI_HANDLE device, EFI_DEVICE_PATH_PROTOCOL *child ) {
+	EFI_BOOT_SERVICES *bs = efi_systab->BootServices;
 	struct efi_driver *efidrv;
 	struct efi_device *efidev;
+	union {
+		EFI_DEVICE_PATH_PROTOCOL *path;
+		void *interface;
+	} path;
+	EFI_DEVICE_PATH_PROTOCOL *path_end;
+	size_t path_len;
 	EFI_STATUS efirc;
 	int rc;
 
 		goto err_already_started;
 	}
 
+	/* Open device path */
+	if ( ( efirc = bs->OpenProtocol ( device,
+					  &efi_device_path_protocol_guid,
+					  &path.interface, efi_image_handle,
+					  device,
+					  EFI_OPEN_PROTOCOL_GET_PROTOCOL ))!=0){
+		rc = -EEFI ( efirc );
+		DBGC ( device, "EFIDRV %s could not open device path: %s\n",
+		       efi_handle_name ( device ), strerror ( rc ) );
+		goto err_open_path;
+	}
+	path_len = ( efi_devpath_len ( path.path ) + sizeof ( *path_end ) );
+
 	/* Allocate and initialise structure */
-	efidev = zalloc ( sizeof ( *efidev ) );
+	efidev = zalloc ( sizeof ( *efidev ) + path_len );
 	if ( ! efidev ) {
 		efirc = EFI_OUT_OF_RESOURCES;
 		goto err_alloc;
 	}
 	efidev->device = device;
 	efidev->dev.desc.bus_type = BUS_TYPE_EFI;
+	efidev->path = ( ( ( void * ) efidev ) + sizeof ( *efidev ) );
+	memcpy ( efidev->path, path.path, path_len );
 	INIT_LIST_HEAD ( &efidev->dev.children );
 	list_add ( &efidev->dev.siblings, &efi_devices );
 
+	/* Close device path */
+	bs->CloseProtocol ( device, &efi_device_path_protocol_guid,
+			    efi_image_handle, device );
+	path.path = NULL;
+
 	/* Try to start this device */
 	for_each_table_entry ( efidrv, EFI_DRIVERS ) {
 		if ( ( rc = efidrv->supported ( device ) ) != 0 ) {
 	list_del ( &efidev->dev.siblings );
 	free ( efidev );
  err_alloc:
+	if ( path.path ) {
+		bs->CloseProtocol ( device, &efi_device_path_protocol_guid,
+				    efi_image_handle, device );
+	}
+ err_open_path:
  err_already_started:
 	return efirc;
 }

src/interface/efi/efi_snp.c

 	EFI_BOOT_SERVICES *bs = efi_systab->BootServices;
 	struct efi_device *efidev;
 	struct efi_snp_device *snpdev;
-	union {
-		EFI_DEVICE_PATH_PROTOCOL *path;
-		void *interface;
-	} path;
 	EFI_DEVICE_PATH_PROTOCOL *path_end;
 	MAC_ADDR_DEVICE_PATH *macpath;
 	size_t path_prefix_len = 0;
 				       sizeof ( snpdev->name[0] ) ),
 		       "%s", netdev->name );
 
-	/* Get the parent device path */
-	if ( ( efirc = bs->OpenProtocol ( efidev->device,
-					  &efi_device_path_protocol_guid,
-					  &path.interface, efi_image_handle,
-					  efidev->device,
-					  EFI_OPEN_PROTOCOL_GET_PROTOCOL ))!=0){
-		rc = -EEFI ( efirc );
-		DBGC ( snpdev, "SNPDEV %p cannot get %s device path: %s\n",
-		       snpdev, efi_handle_name ( efidev->device ),
-		       strerror ( rc ) );
-		goto err_open_device_path;
-	}
-
 	/* Allocate the new device path */
-	path_prefix_len = efi_devpath_len ( path.path );
+	path_prefix_len = efi_devpath_len ( efidev->path );
 	snpdev->path = zalloc ( path_prefix_len + sizeof ( *macpath ) +
 				sizeof ( *path_end ) );
 	if ( ! snpdev->path ) {
 	}
 
 	/* Populate the device path */
-	memcpy ( snpdev->path, path.path, path_prefix_len );
+	memcpy ( snpdev->path, efidev->path, path_prefix_len );
 	macpath = ( ( ( void * ) snpdev->path ) + path_prefix_len );
 	path_end = ( ( void * ) ( macpath + 1 ) );
 	memset ( macpath, 0, sizeof ( *macpath ) );
  err_install_protocol_interface:
 	free ( snpdev->path );
  err_alloc_device_path:
-	bs->CloseProtocol ( efidev->device, &efi_device_path_protocol_guid,
-			    efi_image_handle, efidev->device );
- err_open_device_path:
 	bs->CloseEvent ( snpdev->snp.WaitForPacket );
  err_create_event:
  err_ll_addr_len: