Add initial logic for handling dedicated interconnect situations.

Signed-off-by: Keith Rothman <537074+litghost@users.noreply.github.com>

1 files changed, 129 insertions, 0 deletions

diff --git a/fpga_interchange/dedicated_interconnect.h b/fpga_interchange/dedicated_interconnect.h
new file mode 100644
index 00000000..5fe61d30
--- /dev/null
+++ b/fpga_interchange/dedicated_interconnect.h
@@ -0,0 +1,129 @@
+/*
+ *  nextpnr -- Next Generation Place and Route
+ *
+ *  Copyright (C) 2021  Symbiflow Authors
+ *
+ *
+ *  Permission to use, copy, modify, and/or distribute this software for any
+ *  purpose with or without fee is hereby granted, provided that the above
+ *  copyright notice and this permission notice appear in all copies.
+ *
+ *  THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ *  WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ *  MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ *  ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ *  WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ *  ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ *  OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ *
+ */
+
+#ifndef NEXTPNR_H
+#error Include "dedicated_interconnect.h" via "nextpnr.h" only.
+#endif
+
+NEXTPNR_NAMESPACE_BEGIN
+
+struct TileTypeBelPin {
+    int32_t tile_type;
+    int32_t bel_index;
+    IdString bel_pin;
+
+    bool operator < (const TileTypeBelPin &other) const {
+        if(tile_type >= other.tile_type) {
+            return false;
+        }
+
+        if(bel_index >= other.bel_index) {
+            return false;
+        }
+
+        return bel_pin < other.bel_pin;
+    }
+
+    bool operator ==(const TileTypeBelPin &other) const {
+        return tile_type == other.tile_type && bel_index == other.bel_index && bel_pin == other.bel_pin;
+    }
+    bool operator !=(const TileTypeBelPin &other) const {
+        return tile_type != other.tile_type || bel_index != other.bel_index || bel_pin != other.bel_pin;
+    }
+};
+
+struct DeltaTileTypeBelPin {
+    int32_t delta_x;
+    int32_t delta_y;
+    TileTypeBelPin type_bel_pin;
+
+    bool operator ==(const DeltaTileTypeBelPin &other) const {
+        return delta_x == other.delta_x && delta_y == other.delta_y && type_bel_pin == other.type_bel_pin;
+    }
+    bool operator !=(const DeltaTileTypeBelPin &other) const {
+        return delta_x != other.delta_x || delta_y != other.delta_y || type_bel_pin != other.type_bel_pin;
+    }
+};
+
+NEXTPNR_NAMESPACE_END
+
+template <> struct std::hash<NEXTPNR_NAMESPACE_PREFIX TileTypeBelPin>
+{
+    std::size_t operator()(const NEXTPNR_NAMESPACE_PREFIX TileTypeBelPin &type_bel_pin) const noexcept
+    {
+        std::size_t seed = 0;
+        boost::hash_combine(seed, std::hash<int32_t>()(type_bel_pin.tile_type));
+        boost::hash_combine(seed, std::hash<int32_t>()(type_bel_pin.bel_index));
+        boost::hash_combine(seed, std::hash<NEXTPNR_NAMESPACE_PREFIX IdString>()(type_bel_pin.bel_pin));
+        return seed;
+    }
+};
+
+template <> struct std::hash<NEXTPNR_NAMESPACE_PREFIX DeltaTileTypeBelPin>
+{
+    std::size_t operator()(const NEXTPNR_NAMESPACE_PREFIX DeltaTileTypeBelPin &delta_bel_pin) const noexcept
+    {
+        std::size_t seed = 0;
+        boost::hash_combine(seed, std::hash<int32_t>()(delta_bel_pin.delta_x));
+        boost::hash_combine(seed, std::hash<int32_t>()(delta_bel_pin.delta_y));
+        boost::hash_combine(seed, std::hash<NEXTPNR_NAMESPACE_PREFIX TileTypeBelPin>()(delta_bel_pin.type_bel_pin));
+        return seed;
+    }
+};
+
+NEXTPNR_NAMESPACE_BEGIN
+
+struct Context;
+
+// This class models dedicated interconnect present in the given fabric.
+//
+// Examples of dedicate interconnect:
+//  - IBUF.O -> ISERDES.I
+//  - IBUF.O -> IDELAY.I
+//  - CARRY4.CO[3] -> CARRY4.CIN
+//
+//  Note that CARRY4.CYINIT does not **require** dedicated interconnect, so
+//  it doesn't qualify.
+//
+//  This class discovers dedicated interconnect by examing the routing graph.
+//  This discovery make be expensive, and require caching to accelerate
+//  startup.
+struct DedicatedInterconnect {
+    const Context *ctx;
+
+    std::unordered_map<TileTypeBelPin, std::unordered_set<DeltaTileTypeBelPin>> pins_with_dedicate_interconnect;
+
+    void init(const Context *ctx);
+
+    // Is this BEL placed in a location that is valid based on dedicated
+    // interconnect?
+    //
+    // Note: Only BEL pin sinks are checked.
+    bool isBelLocationValid(BelId bel, const CellInfo* cell) const;
+
+    void find_dedicated_interconnect();
+    void print_dedicated_interconnect() const;
+    bool check_routing(
+        BelId src_bel, IdString src_bel_pin,
+        BelId dst_bel, IdString dst_bel_pin) const;
+    void expand_bel(BelId bel, IdString pin, WireId wire);
+};
+
+NEXTPNR_NAMESPACE_END