[efi] Split efi_netdev_path() out to a separate function

Provide efi_netdev_path() as a standalone function, to allow for reuse
when constructing child device paths.

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

3 files changed, 71 insertions, 37 deletions

diff --git a/src/include/ipxe/efi/efi_path.h b/src/include/ipxe/efi/efi_path.h
index f52410e..d4d4385 100644
--- a/src/include/ipxe/efi/efi_path.h
+++ b/src/include/ipxe/efi/efi_path.h
@@ -13,12 +13,14 @@ FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
 #include <ipxe/efi/efi.h>
 #include <ipxe/efi/Protocol/DevicePath.h>
 
+struct net_device;
 struct uri;
 struct usb_function;
 
 extern EFI_DEVICE_PATH_PROTOCOL *
 efi_path_end ( EFI_DEVICE_PATH_PROTOCOL *path );
 extern size_t efi_path_len ( EFI_DEVICE_PATH_PROTOCOL *path );
+extern EFI_DEVICE_PATH_PROTOCOL * efi_netdev_path ( struct net_device *netdev );
 extern EFI_DEVICE_PATH_PROTOCOL * efi_uri_path ( struct uri *uri );
 extern EFI_DEVICE_PATH_PROTOCOL * efi_usb_path ( struct usb_function *func );
 
diff --git a/src/interface/efi/efi_path.c b/src/interface/efi/efi_path.c
index 6201c02..3faf476 100644
--- a/src/interface/efi/efi_path.c
+++ b/src/interface/efi/efi_path.c
@@ -19,6 +19,9 @@
 
 #include <stdlib.h>
 #include <string.h>
+#include <byteswap.h>
+#include <ipxe/netdevice.h>
+#include <ipxe/vlan.h>
 #include <ipxe/uri.h>
 #include <ipxe/usb.h>
 #include <ipxe/efi/efi.h>
@@ -62,6 +65,68 @@ size_t efi_path_len ( EFI_DEVICE_PATH_PROTOCOL *path ) {
 }
 
 /**
+ * Construct EFI device path for network device
+ *
+ * @v netdev		Network device
+ * @ret path		EFI device path, or NULL on error
+ *
+ * The caller is responsible for eventually calling free() on the
+ * allocated device path.
+ */
+EFI_DEVICE_PATH_PROTOCOL * efi_netdev_path ( struct net_device *netdev ) {
+	struct efi_device *efidev;
+	EFI_DEVICE_PATH_PROTOCOL *path;
+	MAC_ADDR_DEVICE_PATH *macpath;
+	VLAN_DEVICE_PATH *vlanpath;
+	EFI_DEVICE_PATH_PROTOCOL *end;
+	unsigned int tag;
+	size_t prefix_len;
+	size_t len;
+
+	/* Find parent EFI device */
+	efidev = efidev_parent ( netdev->dev );
+	if ( ! efidev )
+		return NULL;
+
+	/* Calculate device path length */
+	prefix_len = efi_path_len ( efidev->path );
+	len = ( prefix_len + sizeof ( *macpath ) + sizeof ( *vlanpath ) +
+		sizeof ( *end ) );
+
+	/* Allocate device path */
+	path = zalloc ( len );
+	if ( ! path )
+		return NULL;
+
+	/* Construct device path */
+	memcpy ( path, efidev->path, prefix_len );
+	macpath = ( ( ( void * ) path ) + prefix_len );
+	macpath->Header.Type = MESSAGING_DEVICE_PATH;
+	macpath->Header.SubType = MSG_MAC_ADDR_DP;
+	macpath->Header.Length[0] = sizeof ( *macpath );
+	assert ( netdev->ll_protocol->ll_addr_len <
+		 sizeof ( macpath->MacAddress ) );
+	memcpy ( &macpath->MacAddress, netdev->ll_addr,
+		 netdev->ll_protocol->ll_addr_len );
+	macpath->IfType = ntohs ( netdev->ll_protocol->ll_proto );
+	if ( ( tag = vlan_tag ( netdev ) ) ) {
+		vlanpath = ( ( ( void * ) macpath ) + sizeof ( *macpath ) );
+		vlanpath->Header.Type = MESSAGING_DEVICE_PATH;
+		vlanpath->Header.SubType = MSG_VLAN_DP;
+		vlanpath->Header.Length[0] = sizeof ( *vlanpath );
+		vlanpath->VlanId = tag;
+		end = ( ( ( void * ) vlanpath ) + sizeof ( *vlanpath ) );
+	} else {
+		end = ( ( ( void * ) macpath ) + sizeof ( *macpath ) );
+	}
+	end->Type = END_DEVICE_PATH_TYPE;
+	end->SubType = END_ENTIRE_DEVICE_PATH_SUBTYPE;
+	end->Length[0] = sizeof ( *end );
+
+	return path;
+}
+
+/**
  * Construct EFI device path for URI
  *
  * @v uri		URI
diff --git a/src/interface/efi/efi_snp.c b/src/interface/efi/efi_snp.c
index f5c736a..91e796a 100644
--- a/src/interface/efi/efi_snp.c
+++ b/src/interface/efi/efi_snp.c
@@ -1624,12 +1624,7 @@ static int efi_snp_probe ( struct net_device *netdev ) {
 	EFI_BOOT_SERVICES *bs = efi_systab->BootServices;
 	struct efi_device *efidev;
 	struct efi_snp_device *snpdev;
-	EFI_DEVICE_PATH_PROTOCOL *path_end;
-	MAC_ADDR_DEVICE_PATH *macpath;
-	VLAN_DEVICE_PATH *vlanpath;
-	size_t path_prefix_len = 0;
 	unsigned int ifcnt;
-	unsigned int tag;
 	void *interface;
 	EFI_STATUS efirc;
 	int rc;
@@ -1714,41 +1709,13 @@ static int efi_snp_probe ( struct net_device *netdev ) {
 				       sizeof ( snpdev->name[0] ) ),
 		       "%s", netdev->name );
 
-	/* Allocate the new device path */
-	path_prefix_len = efi_path_len ( efidev->path );
-	snpdev->path = zalloc ( path_prefix_len + sizeof ( *macpath ) +
-				sizeof ( *vlanpath ) + sizeof ( *path_end ) );
+	/* Construct device path */
+	snpdev->path = efi_netdev_path ( netdev );
 	if ( ! snpdev->path ) {
 		rc = -ENOMEM;
-		goto err_alloc_device_path;
+		goto err_path;
 	}
 
-	/* Populate the device path */
-	memcpy ( snpdev->path, efidev->path, path_prefix_len );
-	macpath = ( ( ( void * ) snpdev->path ) + path_prefix_len );
-	memset ( macpath, 0, sizeof ( *macpath ) );
-	macpath->Header.Type = MESSAGING_DEVICE_PATH;
-	macpath->Header.SubType = MSG_MAC_ADDR_DP;
-	macpath->Header.Length[0] = sizeof ( *macpath );
-	memcpy ( &macpath->MacAddress, netdev->ll_addr,
-		 netdev->ll_protocol->ll_addr_len );
-	macpath->IfType = ntohs ( netdev->ll_protocol->ll_proto );
-	if ( ( tag = vlan_tag ( netdev ) ) ) {
-		vlanpath = ( ( ( void * ) macpath ) + sizeof ( *macpath ) );
-		memset ( vlanpath, 0, sizeof ( *vlanpath ) );
-		vlanpath->Header.Type = MESSAGING_DEVICE_PATH;
-		vlanpath->Header.SubType = MSG_VLAN_DP;
-		vlanpath->Header.Length[0] = sizeof ( *vlanpath );
-		vlanpath->VlanId = tag;
-		path_end = ( ( ( void * ) vlanpath ) + sizeof ( *vlanpath ) );
-	} else {
-		path_end = ( ( ( void * ) macpath ) + sizeof ( *macpath ) );
-	}
-	memset ( path_end, 0, sizeof ( *path_end ) );
-	path_end->Type = END_DEVICE_PATH_TYPE;
-	path_end->SubType = END_ENTIRE_DEVICE_PATH_SUBTYPE;
-	path_end->Length[0] = sizeof ( *path_end );
-
 	/* Install the SNP */
 	if ( ( efirc = bs->InstallMultipleProtocolInterfaces (
 			&snpdev->handle,
@@ -1847,7 +1814,7 @@ static int efi_snp_probe ( struct net_device *netdev ) {
 			NULL );
  err_install_protocol_interface:
 	free ( snpdev->path );
- err_alloc_device_path:
+ err_path:
 	bs->CloseEvent ( snpdev->snp.WaitForPacket );
  err_create_event:
  err_ll_addr_len: