generic: Add a simple packer for generic SLICEs and IOBs

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

1 files changed, 139 insertions, 0 deletions

diff --git a/generic/cells.cc b/generic/cells.cc
new file mode 100644
index 00000000..14b368b2
--- /dev/null
+++ b/generic/cells.cc
@@ -0,0 +1,139 @@
+/*
+ *  nextpnr -- Next Generation Place and Route
+ *
+ *  Copyright (C) 2019  David Shah <david@symbioticeda.com>
+ *
+ *  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.
+ *
+ */
+
+#include "cells.h"
+#include "design_utils.h"
+#include "log.h"
+#include "util.h"
+
+NEXTPNR_NAMESPACE_BEGIN
+
+void add_port(const Context *ctx, CellInfo *cell, std::string name, PortType dir)
+{
+    IdString id = ctx->id(name);
+    NPNR_ASSERT(cell->ports.count(id) == 0);
+    cell->ports[id] = PortInfo{id, nullptr, dir};
+}
+
+std::unique_ptr<CellInfo> create_generic_cell(Context *ctx, IdString type, std::string name)
+{
+    static int auto_idx = 0;
+    std::unique_ptr<CellInfo> new_cell = std::unique_ptr<CellInfo>(new CellInfo());
+    if (name.empty()) {
+        new_cell->name = ctx->id("$nextpnr_" + type.str(ctx) + "_" + std::to_string(auto_idx++));
+    } else {
+        new_cell->name = ctx->id(name);
+    }
+    new_cell->type = type;
+    if (type == ctx->id("GENERIC_SLICE")) {
+        new_cell->params[ctx->id("K")] = std::to_string(ctx->args.K);
+        new_cell->params[ctx->id("INIT")] = "0";
+        new_cell->params[ctx->id("FF_USED")] = "0";
+
+        for (int i = 0; i < ctx->args.K; i++)
+            add_port(ctx, new_cell.get(), "I[" + std::to_string(i) + "]", PORT_IN);
+
+        add_port(ctx, new_cell.get(), "CLK", PORT_IN);
+
+        add_port(ctx, new_cell.get(), "Q", PORT_OUT);
+    } else if (type == ctx->id("GENERIC_IOB")) {
+        new_cell->params[ctx->id("INPUT_USED")] = "0";
+        new_cell->params[ctx->id("OUTPUT_USED")] = "0";
+        new_cell->params[ctx->id("ENABLE_USED")] = "0";
+
+        add_port(ctx, new_cell.get(), "PAD", PORT_INOUT);
+        add_port(ctx, new_cell.get(), "I", PORT_IN);
+        add_port(ctx, new_cell.get(), "EN", PORT_IN);
+        add_port(ctx, new_cell.get(), "O", PORT_OUT);
+    } else {
+        log_error("unable to create generic cell of type %s", type.c_str(ctx));
+    }
+    return new_cell;
+}
+
+void lut_to_lc(const Context *ctx, CellInfo *lut, CellInfo *lc, bool no_dff)
+{
+    lc->params[ctx->id("INIT")] = lut->params[ctx->id("INIT")];
+
+    int lut_k = int_or_default(lut->params, ctx->id("K"), 4);
+    NPNR_ASSERT(lut_k <= ctx->args.K);
+
+    for (int i = 0; i < lut_k; i++) {
+        IdString port = ctx->id("I[" + std::to_string(i) + "]");
+        replace_port(lut, port, lc, port);
+    }
+
+    if (no_dff) {
+        replace_port(lut, ctx->id("Q"), lc, ctx->id("Q"));
+        lc->params[ctx->id("FF_USED")] = "0";
+    }
+}
+
+void dff_to_lc(const Context *ctx, CellInfo *dff, CellInfo *lc, bool pass_thru_lut)
+{
+    lc->params[ctx->id("FF_USED")] = "1";
+    replace_port(dff, ctx->id("CLK"), lc, ctx->id("CLK"));
+
+    if (pass_thru_lut) {
+        lc->params[ctx->id("INIT")] = "2";
+        replace_port(dff, ctx->id("D"), lc, ctx->id("I[0]"));
+    }
+
+    replace_port(dff, ctx->id("Q"), lc, ctx->id("Q"));
+}
+
+void nxio_to_iob(Context *ctx, CellInfo *nxio, CellInfo *iob, std::unordered_set<IdString> &todelete_cells)
+{
+    if (nxio->type == ctx->id("$nextpnr_ibuf")) {
+        iob->params[ctx->id("INPUT_USED")] = "1";
+        replace_port(nxio, ctx->id("O"), iob, ctx->id("O"));
+    } else if (nxio->type == ctx->id("$nextpnr_obuf")) {
+        iob->params[ctx->id("OUTPUT_USED")] = "1";
+        replace_port(nxio, ctx->id("I"), iob, ctx->id("I"));
+    } else if (nxio->type == ctx->id("$nextpnr_iobuf")) {
+        // N.B. tristate will be dealt with below
+        iob->params[ctx->id("INPUT_USED")] = "1";
+        iob->params[ctx->id("OUTPUT_USED")] = "1";
+        replace_port(nxio, ctx->id("I"), iob, ctx->id("I"));
+        replace_port(nxio, ctx->id("O"), iob, ctx->id("O"));
+    } else {
+        NPNR_ASSERT(false);
+    }
+    NetInfo *donet = iob->ports.at(ctx->id("I")).net;
+    CellInfo *tbuf = net_driven_by(
+            ctx, donet, [](const Context *ctx, const CellInfo *cell) { return cell->type == ctx->id("$_TBUF_"); },
+            ctx->id("Y"));
+    if (tbuf) {
+        iob->params[ctx->id("ENABLE_USED")] = "1";
+        replace_port(tbuf, ctx->id("A"), iob, ctx->id("I"));
+        replace_port(tbuf, ctx->id("E"), iob, ctx->id("EN"));
+
+        if (donet->users.size() > 1) {
+            for (auto user : donet->users)
+                log_info("     remaining tristate user: %s.%s\n", user.cell->name.c_str(ctx), user.port.c_str(ctx));
+            log_error("unsupported tristate IO pattern for IO buffer '%s', "
+                      "instantiate GENERIC_IOB manually to ensure correct behaviour\n",
+                      nxio->name.c_str(ctx));
+        }
+        ctx->nets.erase(donet->name);
+        todelete_cells.insert(tbuf->name);
+    }
+}
+
+NEXTPNR_NAMESPACE_END