ice40: Preserve top level IO properly

Signed-off-by: David Shah <dave@ds0.me>

3 files changed, 24 insertions, 16 deletions

diff --git a/ecp5/cells.cc b/ecp5/cells.cc
index b70b412d..9accdd55 100644
--- a/ecp5/cells.cc
+++ b/ecp5/cells.cc
@@ -419,9 +419,9 @@ void nxio_to_tr(Context *ctx, CellInfo *nxio, CellInfo *trio, std::vector<std::u
     NetInfo *donet = trio->ports.at(ctx->id("I")).net, *dinet = trio->ports.at(ctx->id("O")).net;
 
     // Rename I/O nets to avoid conflicts
-    if (donet != nullptr)
+    if (donet != nullptr && donet->name == nxio->name)
         rename_net(ctx, donet, ctx->id(donet->name.str(ctx) + "$TRELLIS_IO_OUT"));
-    if (dinet != nullptr)
+    if (dinet != nullptr && dinet->name == nxio->name)
         rename_net(ctx, dinet, ctx->id(dinet->name.str(ctx) + "$TRELLIS_IO_IN"));
 
     // Create a new top port net for accurate IO timing analysis and simulation netlists
diff --git a/ice40/cells.cc b/ice40/cells.cc
index c4e93d5b..3f1a0fbf 100644
--- a/ice40/cells.cc
+++ b/ice40/cells.cc
@@ -426,7 +426,25 @@ void nxio_to_sb(Context *ctx, CellInfo *nxio, CellInfo *sbio, std::unordered_set
     } else {
         NPNR_ASSERT(false);
     }
-    NetInfo *donet = sbio->ports.at(ctx->id("D_OUT_0")).net;
+    NetInfo *donet = sbio->ports.at(ctx->id("D_OUT_0")).net, *dinet = sbio->ports.at(ctx->id("D_IN_0")).net;
+
+    // Rename I/O nets to avoid conflicts
+    if (donet != nullptr && donet->name == nxio->name)
+        rename_net(ctx, donet, ctx->id(donet->name.str(ctx) + "$SB_IO_OUT"));
+    if (dinet != nullptr && dinet->name == nxio->name)
+        rename_net(ctx, dinet, ctx->id(dinet->name.str(ctx) + "$SB_IO_IN"));
+
+    // Create a new top port net for accurate IO timing analysis and simulation netlists
+    if (ctx->ports.count(nxio->name)) {
+        IdString tn_netname = nxio->name;
+        NPNR_ASSERT(!ctx->nets.count(tn_netname));
+        std::unique_ptr<NetInfo> toplevel_net{new NetInfo};
+        toplevel_net->name = tn_netname;
+        connect_port(ctx, toplevel_net.get(), sbio, ctx->id("PACKAGE_PIN"));
+        ctx->ports[nxio->name].net = toplevel_net.get();
+        ctx->nets[tn_netname] = std::move(toplevel_net);
+    }
+
     CellInfo *tbuf = net_driven_by(
             ctx, donet, [](const Context *ctx, const CellInfo *cell) { return cell->type == ctx->id("$_TBUF_"); },
             ctx->id("Y"));
diff --git a/ice40/pack.cc b/ice40/pack.cc
index a1eba411..90c6de31 100644
--- a/ice40/pack.cc
+++ b/ice40/pack.cc
@@ -459,7 +459,6 @@ static void pack_io(Context *ctx)
 {
     std::unordered_set<IdString> packed_cells;
     std::unordered_set<IdString> delete_nets;
-
     std::vector<std::unique_ptr<CellInfo>> new_cells;
     log_info("Packing IOs..\n");
 
@@ -478,8 +477,7 @@ static void pack_io(Context *ctx)
                     rgb = net->driver.cell;
             }
             if (sb != nullptr) {
-                // Trivial case, SB_IO used. Just destroy the net and the
-                // iobuf
+                // Trivial case, SB_IO used. Just destroy the iobuf
                 log_info("%s feeds SB_IO %s, removing %s %s.\n", ci->name.c_str(ctx), sb->name.c_str(ctx),
                          ci->type.c_str(ctx), ci->name.c_str(ctx));
                 NetInfo *net = sb->ports.at(ctx->id("PACKAGE_PIN")).net;
@@ -490,7 +488,6 @@ static void pack_io(Context *ctx)
                               sb->type.c_str(ctx), sb->name.c_str(ctx));
 
                 if (net != nullptr) {
-
                     if (net->clkconstr != nullptr) {
                         if (sb->ports.count(id_D_IN_0)) {
                             NetInfo *din0_net = sb->ports.at(id_D_IN_0).net;
@@ -509,15 +506,6 @@ static void pack_io(Context *ctx)
                             }
                         }
                     }
-
-                    delete_nets.insert(net->name);
-                    sb->ports.at(ctx->id("PACKAGE_PIN")).net = nullptr;
-                }
-                if (ci->type == ctx->id("$nextpnr_iobuf")) {
-                    NetInfo *net2 = ci->ports.at(ctx->id("I")).net;
-                    if (net2 != nullptr) {
-                        delete_nets.insert(net2->name);
-                    }
                 }
             } else if (rgb != nullptr) {
                 log_info("%s use by SB_RGBA_DRV/SB_RGB_DRV %s, not creating SB_IO\n", ci->name.c_str(ctx),
@@ -533,6 +521,8 @@ static void pack_io(Context *ctx)
                 new_cells.push_back(std::move(ice_cell));
                 sb = new_cells.back().get();
             }
+            for (auto port : ci->ports)
+                disconnect_port(ctx, ci, port.first);
             packed_cells.insert(ci->name);
             std::copy(ci->attrs.begin(), ci->attrs.end(), std::inserter(sb->attrs, sb->attrs.begin()));
         } else if (is_sb_io(ctx, ci) || is_sb_gb_io(ctx, ci)) {