From f87e095558996ce51f7972c89059b9a522d32ac7 Mon Sep 17 00:00:00 2001
From: tangxifan <tangxifan@gmail.com>
Date: Fri, 20 Sep 2024 19:22:39 -0700
Subject: [PATCH] [core] support intermediate driver in clock routing

---
 .../src/annotation/append_clock_rr_graph.cpp  | 12 +----
 .../src/annotation/route_clock_rr_graph.cpp   | 44 +++++++++++++++++++
 2 files changed, 45 insertions(+), 11 deletions(-)

diff --git a/openfpga/src/annotation/append_clock_rr_graph.cpp b/openfpga/src/annotation/append_clock_rr_graph.cpp
index cc9dbe60d..6fe98875c 100644
--- a/openfpga/src/annotation/append_clock_rr_graph.cpp
+++ b/openfpga/src/annotation/append_clock_rr_graph.cpp
@@ -761,24 +761,14 @@ static int add_rr_graph_opin2clk_intermediate_edges(
           /* Get the rr node of destination spine */
           Direction des_spine_direction = clk_ntwk.spine_direction(ispine);
           ClockLevelId des_spine_level = clk_ntwk.spine_level(ispine);
-          vtr::Point<int> des_coord;
+          vtr::Point<int> des_coord(coord.x(), coord.y());
           /* des node depends on the type of routing track and direction. But it should be a starting point at the current SB[x][y] */
           if (des_spine_direction == Direction::INC && clk_ntwk.spine_track_type(ispine) == CHANX) {
             des_coord.set_x(coord.x() + 1);
-            des_coord.set_y(coord.y());
-          } 
-          if (des_spine_direction == Direction::DEC && clk_ntwk.spine_track_type(ispine) == CHANX) {
-            des_coord.set_x(coord.x());
-            des_coord.set_y(coord.y());
           } 
           if (des_spine_direction == Direction::INC && clk_ntwk.spine_track_type(ispine) == CHANY) {
-            des_coord.set_x(coord.x());
             des_coord.set_y(coord.y() + 1);
           } 
-          if (des_spine_direction == Direction::DEC && clk_ntwk.spine_track_type(ispine) == CHANY) {
-            des_coord.set_x(coord.x());
-            des_coord.set_y(coord.y());
-          } 
           RRNodeId des_node = clk_rr_lookup.find_node(
             des_coord.x(), des_coord.y(), clk_tree, des_spine_level, ipin,
             des_spine_direction, verbose);
diff --git a/openfpga/src/annotation/route_clock_rr_graph.cpp b/openfpga/src/annotation/route_clock_rr_graph.cpp
index 79cad9ecb..2ff70bfc5 100644
--- a/openfpga/src/annotation/route_clock_rr_graph.cpp
+++ b/openfpga/src/annotation/route_clock_rr_graph.cpp
@@ -449,6 +449,50 @@ static int rec_expand_and_route_clock_spine(
       des_spine_direction, verbose);
     VTR_ASSERT(rr_graph.valid_node(src_node));
     VTR_ASSERT(rr_graph.valid_node(des_node));
+
+    /* Internal drivers may appear at the intermediate. Check if there are
+     * any defined and related rr_node found as incoming edges. If the
+     * global net is mapped to the internal driver, use it as the previous
+     * node  */
+    size_t use_int_driver = 0;
+    if (!clk_ntwk.spine_intermediate_drivers(curr_spine, des_coord)
+           .empty() &&
+        tree2clk_pin_map.find(curr_pin) != tree2clk_pin_map.end()) {
+      for (RREdgeId cand_edge : rr_graph.node_in_edges(des_node)) {
+        RRNodeId opin_node = rr_graph.edge_src_node(cand_edge);
+        if (OPIN != rr_graph.node_type(opin_node)) {
+          continue;
+        }
+        if (rr_node_gnets[opin_node] != tree2clk_pin_map.at(curr_pin)) {
+          continue;
+        }
+        /* This is the opin node we need, use it as the internal driver */
+        vpr_routing_annotation.set_rr_node_prev_node(rr_graph, des_node,
+                                                     opin_node);
+        vpr_routing_annotation.set_rr_node_net(opin_node,
+                                               tree2clk_pin_map.at(curr_pin));
+        vpr_routing_annotation.set_rr_node_net(des_node,
+                                               tree2clk_pin_map.at(curr_pin));
+        use_int_driver++;
+        VTR_LOGV(verbose,
+                 "Routed intermediate point of spine '%s' at "
+                 "(%lu, %lu) using internal driver\n",
+                 clk_ntwk.spine_name(curr_spine).c_str(), des_coord.x(),
+                 des_coord.y());
+      }
+    }
+    if (use_int_driver > 1) {
+      VTR_LOG_ERROR(
+        "Found %lu internal drivers for the intermediate point (%lu, %lu) for "
+        "spine '%s'!\n Expect only 1!\n",
+        use_int_driver, des_coord.x(), des_coord.y(),
+        clk_ntwk.spine_name(curr_spine).c_str());
+      return CMD_EXEC_FATAL_ERROR;
+    }
+    if (use_int_driver == 1) {
+      continue; /* Used internal driver, early pass. */
+    }
+
     VTR_LOGV(verbose,
              "Routed backbone of spine '%s' from (x=%lu, y=%lu) to (x=%lu, "
              "y=%lu)...\n",