ecp5: Add support for top pseudo diff outputs

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

3 files changed, 42 insertions, 13 deletions

diff --git a/ecp5/bitstream.cc b/ecp5/bitstream.cc
index 66bd639a..207ba048 100644
--- a/ecp5/bitstream.cc
+++ b/ecp5/bitstream.cc
@@ -256,6 +256,18 @@ static std::string get_pic_tile(Context *ctx, BelId bel)
     }
 }
 
+// Get the complement PIC and PIO tiles for a pseudo differential IO
+static std::string get_comp_pio_tile(Context *ctx, BelId bel)
+{
+    NPNR_ASSERT(bel.location.y == 0);
+    return ctx->getTileByTypeAndLocation(0, bel.location.x + 1, "PIOT1");
+}
+static std::string get_comp_pic_tile(Context *ctx, BelId bel)
+{
+    NPNR_ASSERT(bel.location.y == 0);
+    return ctx->getTileByTypeAndLocation(1, bel.location.x + 1, "PICT1");
+}
+
 // Get the list of tiles corresponding to a blockram
 std::vector<std::string> get_bram_tiles(Context *ctx, BelId bel)
 {
@@ -829,18 +841,29 @@ void write_bitstream(Context *ctx, std::string base_config_file, std::string tex
             cc.tiles[pio_tile].add_enum(pio + ".BASE_TYPE", dir + "_" + iotype);
             cc.tiles[pic_tile].add_enum(pio + ".BASE_TYPE", dir + "_" + iotype);
             if (is_differential(ioType_from_str(iotype))) {
-                // Explicitly disable other pair
-                std::string other;
-                if (pio == "PIOA")
-                    other = "PIOB";
-                else if (pio == "PIOC")
-                    other = "PIOD";
-                else
-                    log_error("cannot place differential IO at location %s\n", pio.c_str());
-                // cc.tiles[pio_tile].add_enum(other + ".BASE_TYPE", "_NONE_");
-                // cc.tiles[pic_tile].add_enum(other + ".BASE_TYPE", "_NONE_");
-                cc.tiles[pio_tile].add_enum(other + ".PULLMODE", "NONE");
-                cc.tiles[pio_tile].add_enum(pio + ".PULLMODE", "NONE");
+                if (bel.location.y == 0) {
+                    // Pseudo differential top IO
+                    NPNR_ASSERT(dir == "OUTPUT");
+                    NPNR_ASSERT(pio == "PIOA");
+                    std::string cpio_tile = get_comp_pio_tile(ctx, bel);
+                    std::string cpic_tile = get_comp_pic_tile(ctx, bel);
+                    cc.tiles[cpio_tile].add_enum(pio + ".BASE_TYPE", dir + "_" + iotype);
+                    cc.tiles[cpic_tile].add_enum(pio + ".BASE_TYPE", dir + "_" + iotype);
+                } else {
+                    // Explicitly disable other pair
+                    std::string other;
+                    if (pio == "PIOA")
+                        other = "PIOB";
+                    else if (pio == "PIOC")
+                        other = "PIOD";
+                    else
+                        log_error("cannot place differential IO at location %s\n", pio.c_str());
+                    // cc.tiles[pio_tile].add_enum(other + ".BASE_TYPE", "_NONE_");
+                    // cc.tiles[pic_tile].add_enum(other + ".BASE_TYPE", "_NONE_");
+                    cc.tiles[pio_tile].add_enum(other + ".PULLMODE", "NONE");
+                    cc.tiles[pio_tile].add_enum(pio + ".PULLMODE", "NONE");
+                }
+
             } else if (is_referenced(ioType_from_str(iotype))) {
                 cc.tiles[pio_tile].add_enum(pio + ".PULLMODE", "NONE");
             }
diff --git a/ecp5/iotypes.inc b/ecp5/iotypes.inc
index 5984e79e..ecedf47a 100644
--- a/ecp5/iotypes.inc
+++ b/ecp5/iotypes.inc
@@ -22,6 +22,8 @@ X(SSTL15D_II)
 X(HSUL12D)
 X(LVCMOS33D)
 X(LVCMOS25D)
+X(LVCMOS15D)
+X(LVCMOS12D)
 
 X(LVDS)
 X(BLVDS25)
diff --git a/ecp5/pio.cc b/ecp5/pio.cc
index 65dcd704..5ff375e3 100644
--- a/ecp5/pio.cc
+++ b/ecp5/pio.cc
@@ -109,6 +109,7 @@ IOVoltage get_vccio(IOType type)
     case IOType::SSTL18D_II:
         return IOVoltage::VCC_1V8;
     case IOType::LVCMOS15:
+    case IOType::LVCMOS15D:
     case IOType::SSTL15_I:
     case IOType::SSTL15_II:
     case IOType::SSTL15D_I:
@@ -120,6 +121,7 @@ IOVoltage get_vccio(IOType type)
     case IOType::SSTL135D_II:
         return IOVoltage::VCC_1V35;
     case IOType::LVCMOS12:
+    case IOType::LVCMOS12D:
     case IOType::HSUL12:
     case IOType::HSUL12D:
         return IOVoltage::VCC_1V2;
@@ -159,6 +161,8 @@ bool is_differential(IOType type)
     switch (type) {
     case IOType::LVCMOS33D:
     case IOType::LVCMOS25D:
+    case IOType::LVCMOS15D:
+    case IOType::LVCMOS12D:
     case IOType::LVPECL33:
     case IOType::LVDS:
     case IOType::MLVDS25:
@@ -207,7 +211,7 @@ bool valid_loc_for_io(IOType type, PortType dir, IOSide side, int z)
     bool is_lr = side == IOSide::LEFT || side == IOSide::RIGHT;
     if (is_referenced(type) && !is_lr)
         return false;
-    if (is_differential(type) && (!is_lr || ((z % 2) == 1)))
+    if (is_differential(type) && ((!is_lr && dir != PORT_OUT) || ((z % 2) == 1)))
         return false;
     if ((type == IOType::LVCMOS18D || type == IOType::LVDS) && (dir == PORT_OUT || dir == PORT_INOUT) && z != 0)
         return false;