tools: ynl: Handle byte-order in struct members

Add support for byte-order in struct members in the genetlink-legacy
spec.
Signed-off-by: Donald Hunter <donald.hunter@gmail.com>
Acked-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

Documentation/netlink/genetlink-legacy.yaml

@@ -122,6 +122,8 @@ properties:
                 enum: [ u8, u16, u32, u64, s8, s16, s32, s64, string ]
               len:
                 $ref: '#/$defs/len-or-define'
+              byte-order:
+                enum: [ little-endian, big-endian ]
         # End genetlink-legacy
 
   attribute-sets:

tools/net/ynl/lib/nlspec.py

@@ -226,11 +226,13 @@ class SpecStructMember(SpecElement):
     Represents a single struct member attribute.
 
     Attributes:
-        type    string, type of the member attribute
+        type        string, type of the member attribute
+        byte_order  string or None for native byte order
     """
     def __init__(self, family, yaml):
         super().__init__(family, yaml)
         self.type = yaml['type']
+        self.byte_order = yaml.get('byte-order')
 
 
 class SpecStruct(SpecElement):

tools/net/ynl/lib/ynl.py

@@ -124,7 +124,7 @@ class NlAttr:
         offset = 0
         for m in members:
             # TODO: handle non-scalar members
-            format = self.get_format(m.type)
+            format = self.get_format(m.type, m.byte_order)
             decoded = format.unpack_from(self.raw, offset)
             offset += format.size
             value[m.name] = decoded[0]
@@ -305,7 +305,7 @@ class GenlMsg:
 
         self.fixed_header_attrs = dict()
         for m in fixed_header_members:
-            format = NlAttr.get_format(m.type)
+            format = NlAttr.get_format(m.type, m.byte_order)
             decoded = format.unpack_from(nl_msg.raw, offset)
             offset += format.size
             self.fixed_header_attrs[m.name] = decoded[0]
@@ -542,7 +542,7 @@ class YnlFamily(SpecFamily):
             fixed_header_members = self.consts[op.fixed_header].members
             for m in fixed_header_members:
                 value = vals.pop(m.name)
-                format = NlAttr.get_format(m.type)
+                format = NlAttr.get_format(m.type, m.byte_order)
                 msg += format.pack(value)
         for name, value in vals.items():
             msg += self._add_attr(op.attr_set.name, name, value)