nexus: Add IO packing

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

6 files changed, 155 insertions, 25 deletions

diff --git a/nexus/arch.cc b/nexus/arch.cc
index f309c872..352f789a 100644
--- a/nexus/arch.cc
+++ b/nexus/arch.cc
@@ -459,7 +459,7 @@ bool Arch::route()
 
 // -----------------------------------------------------------------------
 
-CellPinMux Arch::get_cell_pinmux(CellInfo *cell, IdString pin) const
+CellPinMux Arch::get_cell_pinmux(const CellInfo *cell, IdString pin) const
 {
     IdString param = id(stringf("%sMUX", pin.c_str(this)));
     auto fnd_param = cell->params.find(param);
@@ -503,7 +503,7 @@ void Arch::set_cell_pinmux(CellInfo *cell, IdString pin, CellPinMux state)
 
 // -----------------------------------------------------------------------
 
-const PadInfoPOD *Arch::get_pin_data(const std::string &pin) const
+const PadInfoPOD *Arch::get_pkg_pin_data(const std::string &pin) const
 {
     for (size_t i = 0; i < chip_info->num_pads; i++) {
         const PadInfoPOD *pad = &(chip_info->pads[i]);
@@ -537,9 +537,8 @@ Loc Arch::get_pad_loc(const PadInfoPOD *pad) const
     return loc;
 }
 
-BelId Arch::get_pin_bel(const std::string &pin) const
+BelId Arch::get_pad_pio_bel(const PadInfoPOD *pad) const
 {
-    const PadInfoPOD *pad = get_pin_data(pin);
     if (pad == nullptr)
         return BelId();
     return getBelByLocation(get_pad_loc(pad));
@@ -574,6 +573,17 @@ const PadInfoPOD *Arch::get_bel_pad(BelId bel) const
     return nullptr;
 }
 
+std::string Arch::get_pad_functions(const PadInfoPOD *pad) const
+{
+    std::string s;
+    for (size_t i = 0; i < pad->num_funcs; i++) {
+        if (!s.empty())
+            s += '/';
+        s += IdString(pad->func_strs[i]).str(this);
+    }
+    return s;
+}
+
 // -----------------------------------------------------------------------
 
 #ifdef WITH_HEAP
diff --git a/nexus/arch.h b/nexus/arch.h
index 3beef3cd..2f84b25d 100644
--- a/nexus/arch.h
+++ b/nexus/arch.h
@@ -1429,15 +1429,16 @@ struct Arch : BaseCtx
 
     bool nexus_logic_tile_valid(LogicTileStatus &lts) const;
 
-    CellPinMux get_cell_pinmux(CellInfo *cell, IdString pin) const;
+    CellPinMux get_cell_pinmux(const CellInfo *cell, IdString pin) const;
     void set_cell_pinmux(CellInfo *cell, IdString pin, CellPinMux state);
 
     // -------------------------------------------------
 
-    const PadInfoPOD *get_pin_data(const std::string &pin) const;
+    const PadInfoPOD *get_pkg_pin_data(const std::string &pin) const;
     Loc get_pad_loc(const PadInfoPOD *pad) const;
-    BelId get_pin_bel(const std::string &pin) const;
+    BelId get_pad_pio_bel(const PadInfoPOD *pad) const;
     const PadInfoPOD *get_bel_pad(BelId bel) const;
+    std::string get_pad_functions(const PadInfoPOD *pad) const;
 
     // -------------------------------------------------
 
diff --git a/nexus/constids.inc b/nexus/constids.inc
index 6bf32654..b4aa5077 100644
--- a/nexus/constids.inc
+++ b/nexus/constids.inc
@@ -59,6 +59,10 @@ X(DOLP)
 X(INLP)
 X(INADC)
 
+X(DIFFIO18_CORE)
+X(HSRXEN)
+X(HSTXEN)
+
 X(LUT4)
 X(INIT)
 X(Z)
@@ -68,7 +72,6 @@ X(INIT0)
 X(INIT1)
 
 X(INV)
-X(BB)
 X(VHI)
 X(VLO)
 
@@ -138,3 +141,17 @@ X(RSTA)
 X(RSTB)
 
 X(LOC)
+
+X(IB)
+X(OB)
+X(OBZ)
+X(BB)
+X(BB_I3C_A)
+
+X(SEIO33)
+X(SEIO18)
+X(DIFFIO18)
+X(IOPAD)
+X(PADDO)
+X(PADDI)
+X(PADDT)
diff --git a/nexus/fasm.cc b/nexus/fasm.cc
index 0429e83a..e9a4572f 100644
--- a/nexus/fasm.cc
+++ b/nexus/fasm.cc
@@ -91,6 +91,17 @@ struct NexusFasmWriter
         }
     }
 
+    void write_ioattr(const CellInfo *cell, const std::string &name, const std::string &defval = "")
+    {
+        auto fnd = cell->attrs.find(ctx->id(name));
+        if (fnd == cell->attrs.end()) {
+            if (!defval.empty())
+                write_bit(stringf("%s.%s", name.c_str(), defval.c_str()));
+        } else {
+            write_bit(stringf("%s.%s", name.c_str(), fnd->second.c_str()));
+        }
+    }
+
     NexusFasmWriter(const Context *ctx, std::ostream &out) : ctx(ctx), out(out) {}
     std::string tile_name(int loc, const PhysicalTileInfoPOD &tile)
     {
@@ -195,14 +206,16 @@ struct NexusFasmWriter
         push_tile(bel.tile);
         push_belname(bel);
         const NetInfo *t = get_net_or_empty(cell, id_T);
+        auto tmux = ctx->get_cell_pinmux(cell, id_T);
         bool is_input = false, is_output = false;
-        if (t == nullptr || t->name == ctx->id("$PACKER_VCC_NET")) {
-            is_input = true;
-        } else if (t->name == ctx->id("$PACKER_GND_NET")) {
+        if (tmux == PINMUX_0) {
             is_output = true;
+        } else if (tmux == PINMUX_1 || t == nullptr) {
+            is_input = true;
         }
         const char *iodir = is_input ? "INPUT" : (is_output ? "OUTPUT" : "BIDIR");
         write_bit(stringf("BASE_TYPE.%s_%s", iodir, str_or_default(cell->attrs, id_IO_TYPE, "LVCMOS33").c_str()));
+        write_ioattr(cell, "PULLMODE", "NONE");
         pop(2);
     }
     void write_io18(const CellInfo *cell)
@@ -212,14 +225,16 @@ struct NexusFasmWriter
         push_belname(bel);
         push("SEIO18");
         const NetInfo *t = get_net_or_empty(cell, id_T);
+        auto tmux = ctx->get_cell_pinmux(cell, id_T);
         bool is_input = false, is_output = false;
-        if (t == nullptr || t->name == ctx->id("$PACKER_VCC_NET")) {
-            is_input = true;
-        } else if (t->name == ctx->id("$PACKER_GND_NET")) {
+        if (tmux == PINMUX_0) {
             is_output = true;
+        } else if (tmux == PINMUX_1 || t == nullptr) {
+            is_input = true;
         }
         const char *iodir = is_input ? "INPUT" : (is_output ? "OUTPUT" : "BIDIR");
         write_bit(stringf("BASE_TYPE.%s_%s", iodir, str_or_default(cell->attrs, id_IO_TYPE, "LVCMOS18H").c_str()));
+        write_ioattr(cell, "PULLMODE", "NONE");
         pop(3);
     }
     void write_osc(const CellInfo *cell)
diff --git a/nexus/pack.cc b/nexus/pack.cc
index 3b53ea55..0ef3eb79 100644
--- a/nexus/pack.cc
+++ b/nexus/pack.cc
@@ -502,7 +502,7 @@ struct NexusPacker
                 // Might have an output buffer (OB etc) connected to it
                 is_npnr_iob = true;
                 NetInfo *i = get_net_or_empty(ci, id_I);
-                if (i == nullptr && i->driver.cell != nullptr) {
+                if (i != nullptr && i->driver.cell != nullptr) {
                     if (top_port.cell != nullptr)
                         log_error("Top level '%s' has multiple input/output buffers\n", ctx->nameOf(port.first));
                     top_port = i->driver;
@@ -531,21 +531,104 @@ struct NexusPacker
         }
     }
 
+    BelId get_io_bel(CellInfo *ci)
+    {
+        if (!ci->attrs.count(id_BEL))
+            return BelId();
+        return ctx->getBelByName(ctx->id(ci->attrs.at(id_BEL).as_string()));
+    }
+
     void pack_io()
     {
+        std::unordered_set<IdString> iob_types = {id_IB,          id_OB,          id_OBZ,          id_BB,
+                                                  id_BB_I3C_A,    id_SEIO33,      id_SEIO18,       id_DIFFIO18,
+                                                  id_SEIO33_CORE, id_SEIO18_CORE, id_DIFFIO18_CORE};
+
+        std::unordered_map<IdString, XFormRule> io_rules;
+
+        // For the low level primitives, make sure we always preserve their type
+        io_rules[id_SEIO33_CORE].new_type = id_SEIO33_CORE;
+        io_rules[id_SEIO18_CORE].new_type = id_SEIO18_CORE;
+        io_rules[id_DIFFIO18_CORE].new_type = id_DIFFIO18_CORE;
+
+        // Some IO buffer types need a bit of pin renaming, too
+        io_rules[id_SEIO33].new_type = id_SEIO33_CORE;
+        io_rules[id_SEIO33].port_xform[id_PADDI] = id_O;
+        io_rules[id_SEIO33].port_xform[id_PADDO] = id_I;
+        io_rules[id_SEIO33].port_xform[id_PADDT] = id_T;
+        io_rules[id_SEIO33].port_xform[id_IOPAD] = id_B;
+
+        io_rules[id_BB_I3C_A] = io_rules[id_SEIO33];
+
+        io_rules[id_SEIO18] = io_rules[id_SEIO33];
+        io_rules[id_SEIO18].new_type = id_SEIO18_CORE;
+
+        io_rules[id_DIFFIO18] = io_rules[id_SEIO33];
+        io_rules[id_DIFFIO18].new_type = id_DIFFIO18_CORE;
+
+        // Stage 0: deal with top level inserted IO buffers
+        prepare_io();
+
+        // Stage 1: setup constraints
         for (auto cell : sorted(ctx->cells)) {
             CellInfo *ci = cell.second;
-            if (ci->type == id_SEIO33_CORE || ci->type == id_SEIO18_CORE) {
-                auto fnd_loc = ci->attrs.find(id_LOC);
-                if (fnd_loc == ci->attrs.end())
-                    continue;
-                BelId bel = ctx->get_pin_bel(fnd_loc->second.as_string());
-                if (bel == BelId())
-                    log_error("cannot constrain IO '%s', no PIO pin named '%s'\n", ctx->nameOf(ci),
-                              fnd_loc->second.as_string().c_str());
+            // Iterate through all IO buffer primitives
+            if (!iob_types.count(ci->type))
+                continue;
+            // We need all IO constrained so we can pick the right IO bel type
+            // An improvement would be to allocate unconstrained IO here
+            if (!ci->attrs.count(id_LOC))
+                log_error("Found unconstrained IO '%s', these are currently unsupported\n", ctx->nameOf(ci));
+            // Convert package pin constraint to bel constraint
+            std::string loc = ci->attrs.at(id_LOC).as_string();
+            auto pad_info = ctx->get_pkg_pin_data(loc);
+            if (pad_info == nullptr)
+                log_error("IO '%s' is constrained to invalid pin '%s'\n", ctx->nameOf(ci), loc.c_str());
+            auto func = ctx->get_pad_functions(pad_info);
+            BelId bel = ctx->get_pad_pio_bel(pad_info);
+
+            if (bel == BelId()) {
+                log_error("IO '%s' is constrained to pin %s (%s) which is not a general purpose IO pin.\n",
+                          ctx->nameOf(ci), loc.c_str(), func.c_str());
+            } else {
+
+                // Get IO type for reporting purposes
+                std::string io_type = str_or_default(ci->attrs, id_IO_TYPE, "LVCMOS33");
+
+                log_info("Constraining %s IO '%s' to pin %s (%s%sbel %s)\n", io_type.c_str(), ctx->nameOf(ci),
+                         loc.c_str(), func.c_str(), func.empty() ? "" : "; ", ctx->nameOfBel(bel));
                 ci->attrs[id_BEL] = ctx->getBelName(bel).str(ctx);
             }
         }
+        // Stage 2: apply rules for primitives that need them
+        generic_xform(io_rules, false);
+        // Stage 3: all other IO primitives become their bel type
+        for (auto cell : sorted(ctx->cells)) {
+            CellInfo *ci = cell.second;
+            // Iterate through all IO buffer primitives
+            if (!iob_types.count(ci->type))
+                continue;
+            // Skip those dealt with in stage 2
+            if (io_rules.count(ci->type))
+                continue;
+            // For non-bidirectional IO, we also need to configure tristate and rename B
+            if (ci->type == id_IB) {
+                ctx->set_cell_pinmux(ci, id_T, PINMUX_1);
+                rename_port(ctx, ci, id_I, id_B);
+            } else if (ci->type == id_OB) {
+                ctx->set_cell_pinmux(ci, id_T, PINMUX_0);
+                rename_port(ctx, ci, id_O, id_B);
+            } else if (ci->type == id_OBZ) {
+                ctx->set_cell_pinmux(ci, id_T, PINMUX_SIG);
+                rename_port(ctx, ci, id_O, id_B);
+            }
+            // Get the IO bel
+            BelId bel = get_io_bel(ci);
+            // Set the cell type to the bel type
+            IdString type = ctx->getBelType(bel);
+            NPNR_ASSERT(type != IdString());
+            ci->type = type;
+        }
     }
 
     explicit NexusPacker(Context *ctx) : ctx(ctx) {}
diff --git a/nexus/pdc.cc b/nexus/pdc.cc
index 60cc511c..98a44276 100644
--- a/nexus/pdc.cc
+++ b/nexus/pdc.cc
@@ -304,8 +304,12 @@ struct PDCParser
                     if (!val.is_string)
                         log_error("expecting string argument to -iobuf (line %d)\n", lineno);
                     std::stringstream ss(val.str);
-                    std::string k, v;
-                    while (ss >> k >> v) {
+                    std::string kv;
+                    while (ss >> kv) {
+                        auto eqp = kv.find('=');
+                        if (eqp == std::string::npos)
+                            log_error("expected key-value pair separated by '=' (line %d)", lineno);
+                        std::string k = kv.substr(0, eqp), v = kv.substr(eqp + 1);
                         args[ctx->id(k)] = v;
                     }
                 } else {