Merge pull request #79 from YosysHQ/ice40lvds

ice40: Adding LVDS input support

8 files changed, 88 insertions, 13 deletions

diff --git a/ice40/arch.cc b/ice40/arch.cc
index 3983a24e..43a3dec2 100644
--- a/ice40/arch.cc
+++ b/ice40/arch.cc
@@ -959,7 +959,6 @@ void Arch::assignArchInfo()
 
 void Arch::assignCellInfo(CellInfo *cell)
 {
-    cell->belType = cell->type;
     if (cell->type == id_ICESTORM_LC) {
         cell->lcInfo.dffEnable = bool_or_default(cell->params, id_DFF_ENABLE);
         cell->lcInfo.carryEnable = bool_or_default(cell->params, id_CARRY_ENABLE);
@@ -976,6 +975,8 @@ void Arch::assignCellInfo(CellInfo *cell)
             cell->lcInfo.inputCount++;
         if (get_net_or_empty(cell, id_I3))
             cell->lcInfo.inputCount++;
+    } else if (cell->type == id_SB_IO) {
+        cell->ioInfo.lvds = str_or_default(cell->params, id_IO_STANDARD, "SB_LVCMOS") == "SB_LVDS_INPUT";
     }
 }
 
diff --git a/ice40/arch_place.cc b/ice40/arch_place.cc
index c69fd34f..b436f7d7 100644
--- a/ice40/arch_place.cc
+++ b/ice40/arch_place.cc
@@ -34,7 +34,7 @@ bool Arch::logicCellsCompatible(const CellInfo** it, const size_t size) const
     int locals_count = 0;
 
     for (auto cell : boost::make_iterator_range(it, it+size)) {
-        NPNR_ASSERT(cell->belType == id_ICESTORM_LC);
+        NPNR_ASSERT(cell->type == id_ICESTORM_LC);
         if (cell->lcInfo.dffEnable) {
             if (!dffs_exist) {
                 dffs_exist = true;
@@ -139,6 +139,27 @@ bool Arch::isValidBelForCell(CellInfo *cell, BelId bel) const
                 }
             }
         }
+        Loc ioLoc = getBelLocation(bel);
+        Loc compLoc = ioLoc;
+        compLoc.z = 1 - compLoc.z;
+
+        // Check LVDS pairing
+        if (cell->ioInfo.lvds) {
+            // Check correct z and complement location is free
+            if (ioLoc.z != 0)
+                return false;
+            BelId compBel = getBelByLocation(compLoc);
+            CellInfo *compCell = getBoundBelCell(compBel);
+            if (compCell)
+                return false;
+        } else {
+            // Check LVDS IO is not placed at complement location
+            BelId compBel = getBelByLocation(compLoc);
+            CellInfo *compCell = getBoundBelCell(compBel);
+            if (compCell && compCell->ioInfo.lvds)
+                return false;
+        }
+
         return getBelPackagePin(bel) != "";
     } else if (cell->type == id_SB_GB) {
         NPNR_ASSERT(cell->ports.at(id_GLOBAL_BUFFER_OUTPUT).net != nullptr);
diff --git a/ice40/archdefs.h b/ice40/archdefs.h
index 360617fd..c04033e7 100644
--- a/ice40/archdefs.h
+++ b/ice40/archdefs.h
@@ -134,7 +134,6 @@ struct NetInfo;
 
 struct ArchCellInfo
 {
-    IdString belType;
     union
     {
         struct
@@ -145,6 +144,11 @@ struct ArchCellInfo
             int inputCount;
             const NetInfo *clk, *cen, *sr;
         } lcInfo;
+        struct
+        {
+            bool lvds;
+            // TODO: clk packing checks...
+        } ioInfo;
     };
 };
 
diff --git a/ice40/bitstream.cc b/ice40/bitstream.cc
index 4ea91011..124be092 100644
--- a/ice40/bitstream.cc
+++ b/ice40/bitstream.cc
@@ -447,6 +447,8 @@ void write_asc(const Context *ctx, std::ostream &out)
             unsigned pin_type = get_param_or_def(cell.second.get(), ctx->id("PIN_TYPE"));

             bool neg_trigger = get_param_or_def(cell.second.get(), ctx->id("NEG_TRIGGER"));

             bool pullup = get_param_or_def(cell.second.get(), ctx->id("PULLUP"));

+            bool lvds = get_param_str_or_def(cell.second.get(), ctx->id("IO_STANDARD")) == "SB_LVDS_INPUT";

+

             for (int i = 0; i < 6; i++) {

                 bool val = (pin_type >> i) & 0x01;

                 set_config(ti, config.at(y).at(x), "IOB_" + std::to_string(z) + ".PINTYPE_" + std::to_string(i), val);

@@ -457,12 +459,20 @@ void write_asc(const Context *ctx, std::ostream &out)
             std::tie(iex, iey, iez) = ieren;

             NPNR_ASSERT(iez != -1);

 

-            bool input_en = false;

-            if ((ctx->wire_to_net[ctx->getBelPinWire(bel, id_D_IN_0).index] != nullptr) ||

-                (ctx->wire_to_net[ctx->getBelPinWire(bel, id_D_IN_1).index] != nullptr)) {

-                input_en = true;

+            bool input_en;

+            if (lvds) {

+                input_en = false;

+                pullup = false;

+            } else {

+                if ((ctx->wire_to_net[ctx->getBelPinWire(bel, id_D_IN_0).index] != nullptr) ||

+                    (ctx->wire_to_net[ctx->getBelPinWire(bel, id_D_IN_1).index] != nullptr)) {

+                    input_en = true;

+                } else {

+                    input_en = false;

+                }

             }

 

+

             if (ctx->args.type == ArchArgs::LP1K || ctx->args.type == ArchArgs::HX1K) {

                 set_config(ti, config.at(iey).at(iex), "IoCtrl.IE_" + std::to_string(iez), !input_en);

                 set_config(ti, config.at(iey).at(iex), "IoCtrl.REN_" + std::to_string(iez), !pullup);

@@ -478,6 +488,33 @@ void write_asc(const Context *ctx, std::ostream &out)
                     set_config(ti, config.at(iey).at(iex), "IoCtrl.cf_bit_35", !pullup);

                 }

             }

+

+            if (lvds) {

+                NPNR_ASSERT(z == 0);

+                set_config(ti, config.at(y).at(x), "IoCtrl.LVDS", true);

+                // Set comp IO config

+                auto comp_ieren = get_ieren(bi, x, y, 1);

+                int ciex, ciey, ciez;

+                std::tie(ciex, ciey, ciez) = comp_ieren;

+

+                if (ctx->args.type == ArchArgs::LP1K || ctx->args.type == ArchArgs::HX1K) {

+                    set_config(ti, config.at(ciey).at(ciex), "IoCtrl.IE_" + std::to_string(ciez), !input_en);

+                    set_config(ti, config.at(ciey).at(ciex), "IoCtrl.REN_" + std::to_string(ciez), !pullup);

+                } else {

+                    set_config(ti, config.at(ciey).at(ciex), "IoCtrl.IE_" + std::to_string(ciez), input_en);

+                    set_config(ti, config.at(ciey).at(ciex), "IoCtrl.REN_" + std::to_string(ciez), !pullup);

+                }

+

+                if (ctx->args.type == ArchArgs::UP5K) {

+                    if (ciez == 0) {

+                        set_config(ti, config.at(ciey).at(ciex), "IoCtrl.cf_bit_39", !pullup);

+                    } else if (iez == 1) {

+                        set_config(ti, config.at(ciey).at(ciex), "IoCtrl.cf_bit_35", !pullup);

+                    }

+                }

+

+

+            }

         } else if (cell.second->type == ctx->id("SB_GB")) {

             // no cell config bits

         } else if (cell.second->type == ctx->id("ICESTORM_RAM")) {

@@ -630,6 +667,13 @@ void write_asc(const Context *ctx, std::ostream &out)
             int iex, iey, iez;

             std::tie(iex, iey, iez) = ieren;

             if (iez != -1) {

+                // IO is not actually unused if part of an LVDS pair

+                if (z == 1) {

+                    BelId lvds0 = ctx->getBelByLocation(Loc{x, y, 0});

+                    const CellInfo *lvds0cell = ctx->getBoundBelCell(lvds0);

+                    if (lvds0cell != nullptr && lvds0cell->ioInfo.lvds)

+                        continue;

+                }

                 set_ie_bit_logical(ctx, ti, config.at(iey).at(iex), "IoCtrl.IE_" + std::to_string(iez), true);

                 set_ie_bit_logical(ctx, ti, config.at(iey).at(iex), "IoCtrl.REN_" + std::to_string(iez), false);

             }

diff --git a/ice40/cells.cc b/ice40/cells.cc
index 1c1e7a05..886dae2a 100644
--- a/ice40/cells.cc
+++ b/ice40/cells.cc
@@ -314,7 +314,7 @@ void dff_to_lc(const Context *ctx, CellInfo *dff, CellInfo *lc, bool pass_thru_l
     replace_port(dff, ctx->id("Q"), lc, ctx->id("O"));
 }
 
-void nxio_to_sb(Context *ctx, CellInfo *nxio, CellInfo *sbio)
+void nxio_to_sb(Context *ctx, CellInfo *nxio, CellInfo *sbio, std::unordered_set<IdString> &todelete_cells)
 {
     if (nxio->type == ctx->id("$nextpnr_ibuf")) {
         sbio->params[ctx->id("PIN_TYPE")] = "1";
@@ -341,12 +341,16 @@ void nxio_to_sb(Context *ctx, CellInfo *nxio, CellInfo *sbio)
         sbio->params[ctx->id("PIN_TYPE")] = "41";
         replace_port(tbuf, ctx->id("A"), sbio, ctx->id("D_OUT_0"));
         replace_port(tbuf, ctx->id("E"), sbio, ctx->id("OUTPUT_ENABLE"));
-        ctx->nets.erase(donet->name);
-        if (!donet->users.empty())
+
+        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 SB_IO manually to ensure correct behaviour\n",
                       nxio->name.c_str(ctx));
-        ctx->cells.erase(tbuf->name);
+        }
+        ctx->nets.erase(donet->name);
+        todelete_cells.insert(tbuf->name);
     }
 }
 
diff --git a/ice40/cells.h b/ice40/cells.h
index 16135448..054388ac 100644
--- a/ice40/cells.h
+++ b/ice40/cells.h
@@ -98,7 +98,7 @@ void lut_to_lc(const Context *ctx, CellInfo *lut, CellInfo *lc, bool no_dff = tr
 void dff_to_lc(const Context *ctx, CellInfo *dff, CellInfo *lc, bool pass_thru_lut = false);
 
 // Convert a nextpnr IO buffer to a SB_IO
-void nxio_to_sb(Context *ctx, CellInfo *nxio, CellInfo *sbio);
+void nxio_to_sb(Context *ctx, CellInfo *nxio, CellInfo *sbio, std::unordered_set<IdString> &todelete_cells);
 
 // Return true if a port is a clock port
 bool is_clock_port(const BaseCtx *ctx, const PortRef &port);
diff --git a/ice40/constids.inc b/ice40/constids.inc
index adcea7ad..dad08e59 100644
--- a/ice40/constids.inc
+++ b/ice40/constids.inc
@@ -435,3 +435,4 @@ X(ICESTORM_SPRAM)
 X(DFF_ENABLE)
 X(CARRY_ENABLE)
 X(NEG_CLK)
+X(IO_STANDARD)
\ No newline at end of file
diff --git a/ice40/pack.cc b/ice40/pack.cc
index 01cb3855..07c003d1 100644
--- a/ice40/pack.cc
+++ b/ice40/pack.cc
@@ -424,7 +424,7 @@ static void pack_io(Context *ctx)
                 // Create a SB_IO buffer
                 std::unique_ptr<CellInfo> ice_cell =
                         create_ice_cell(ctx, ctx->id("SB_IO"), ci->name.str(ctx) + "$sb_io");
-                nxio_to_sb(ctx, ci, ice_cell.get());
+                nxio_to_sb(ctx, ci, ice_cell.get(), packed_cells);
                 new_cells.push_back(std::move(ice_cell));
                 sb = new_cells.back().get();
             }