[VOL-1460]

- Imported protobuf definitions from pyvoltha at
  https://gerrit.opencord.org/gitweb?p=pyvoltha.git, commit hash:
  944aee71301b8ddb211b6e51d685f56d5c4a911b

- Imported upstream Google API protos from
  https://github.com/googleapis/googleapis, commit hash:
  5a90fbea68ce4a6e87c20d2df10df5ecd88299ff

- Fixed `import` paths and directory heirarchy in protobuf definitions
  to be compatible with both python 2 and 3.

- Created Makefile scaffold to generate language-specific bindings for
  python and go

Change-Id: Idd6b6b985a5eae4c38d40dd07ae78744c09e37f5
diff --git a/protos/voltha_protos/logical_device.proto b/protos/voltha_protos/logical_device.proto
new file mode 100644
index 0000000..4af0a14
--- /dev/null
+++ b/protos/voltha_protos/logical_device.proto
@@ -0,0 +1,61 @@
+syntax = "proto3";
+
+option go_package = "github.com/opencord/voltha-go/protos/voltha";
+
+package voltha;
+
+import "google/api/annotations.proto";
+import "voltha_protos/meta.proto";
+import "voltha_protos/openflow_13.proto";
+
+message LogicalPortId {
+    // unique id of logical device
+    string id = 1;
+
+    // id of the port on the logical device
+    string port_id = 2;
+}
+
+message LogicalPort {
+    string id = 1;
+    openflow_13.ofp_port ofp_port = 2;
+    string device_id = 3;
+    uint32 device_port_no = 4;
+    bool root_port = 5;
+}
+
+message LogicalPorts {
+    repeated LogicalPort items = 1;
+}
+
+message LogicalDevice {
+
+    // unique id of logical device
+    string id = 1;
+
+    // unique datapath id for the logical device (used by the SDN controller)
+    uint64 datapath_id = 2;
+
+    // device description
+    openflow_13.ofp_desc desc = 3;
+
+    // device features
+    openflow_13.ofp_switch_features switch_features = 4;
+
+    // name of the root device anchoring logical device
+    string root_device_id = 5;
+
+    // logical device ports
+    repeated LogicalPort ports = 128 [(child_node) = {key: "id"}];
+
+    // flows configured on the logical device
+    openflow_13.Flows flows = 129 [(child_node) = {}];
+
+    // flow groups configured on the logical device
+    openflow_13.FlowGroups flow_groups = 130 [(child_node) = {}];
+
+}
+
+message LogicalDevices {
+    repeated LogicalDevice items = 1;
+}