diff --git a/common/nextpnr.h b/common/nextpnr.h
index 021772fe..9ee00a50 100644
--- a/common/nextpnr.h
+++ b/common/nextpnr.h
@@ -173,6 +173,9 @@ struct Loc
 
     bool operator==(const Loc &other) const { return (x == other.x) && (y == other.y) && (z == other.z); }
     bool operator!=(const Loc &other) const { return (x != other.x) || (y != other.y) || (z == other.z); }
+
+    Loc(int x, int y, int z) : x(x), y(y), z(z) {}
+    Loc() {}
 };
 
 NEXTPNR_NAMESPACE_END
diff --git a/common/router1.cc b/common/router1.cc
index fbf3c467..21c54e4c 100644
--- a/common/router1.cc
+++ b/common/router1.cc
@@ -210,6 +210,7 @@ struct Router
                     else
                         overtimeRevisitCnt++;
                 }
+                    
 
                 QueuedWire next_qw;
                 next_qw.wire = next_wire;
diff --git a/gui/fpgaviewwidget.cc b/gui/fpgaviewwidget.cc
index e21af678..cd042af5 100644
--- a/gui/fpgaviewwidget.cc
+++ b/gui/fpgaviewwidget.cc
@@ -400,6 +400,7 @@ void FPGAViewWidget::paintGL()
     // Calculate world thickness to achieve a screen 1px/1.1px line.
     float thick1Px = mouseToWorldCoordinates(1, 0).x();
     float thick11Px = mouseToWorldCoordinates(1.1, 0).x();
+    float thick2Px = mouseToWorldCoordinates(2, 0).x();
 
     // Draw grid.
     auto grid = LineShaderData();
@@ -418,7 +419,7 @@ void FPGAViewWidget::paintGL()
     for (int i = 0; i < 8; i++)
         lineShader_.draw(rendererData_->highlighted[i], colors_.highlight[i], thick11Px, matrix);
 
-    lineShader_.draw(rendererData_->selected, colors_.selected, thick11Px, matrix);
+    lineShader_.draw(rendererData_->selected, colors_.selected, thick2Px, matrix);
     rendererDataLock_.unlock();
 }
 
diff --git a/ice40/arch.cc b/ice40/arch.cc
index 65b21afd..d6ef800d 100644
--- a/ice40/arch.cc
+++ b/ice40/arch.cc
@@ -331,11 +331,12 @@ WireId Arch::getBelPinWire(BelId bel, PortPin pin) const
     int num_bel_wires = chip_info->bel_data[bel.index].num_bel_wires;
     const BelWirePOD *bel_wires = chip_info->bel_data[bel.index].bel_wires.get();
 
-    for (int i = 0; i < num_bel_wires; i++)
+    for (int i = 0; i < num_bel_wires; i++) {
         if (bel_wires[i].port == pin) {
             ret.index = bel_wires[i].wire_index;
             break;
         }
+    }
 
     return ret;
 }
diff --git a/ice40/bitstream.cc b/ice40/bitstream.cc
index 9ac8e857..77d92a89 100644
--- a/ice40/bitstream.cc
+++ b/ice40/bitstream.cc
@@ -74,23 +74,33 @@ void set_config(const TileInfoPOD &ti, std::vector<std::vector<int8_t>> &tile_cf
         for (int i = 0; i < cfg.num_bits; i++) {
             int8_t &cbit = tile_cfg.at(cfg.bits[i].row).at(cfg.bits[i].col);
             if (cbit && !value)
-                log_error("clearing already set config bit %s", name.c_str());
+                log_error("clearing already set config bit %s\n", name.c_str());
             cbit = value;
         }
     } else {
         int8_t &cbit = tile_cfg.at(cfg.bits[index].row).at(cfg.bits[index].col);
         cbit = value;
         if (cbit && !value)
-            log_error("clearing already set config bit %s[%d]", name.c_str(), index);
+            log_error("clearing already set config bit %s[%d]\n", name.c_str(), index);
+    }
+}
+
+// Set an IE_{EN,REN} logical bit in a tile config. Logical means enabled.
+// On {HX,LP}1K devices these bits are active low, so we need to inver them.
+void set_ie_bit_logical(const Context *ctx, const TileInfoPOD &ti, std::vector<std::vector<int8_t>> &tile_cfg, const std::string &name, bool value) {
+    if (ctx->args.type == ArchArgs::LP1K || ctx->args.type == ArchArgs::HX1K) {
+        set_config(ti, tile_cfg, name, !value);
+    } else {
+        set_config(ti, tile_cfg, name, value);
     }
 }
 
 int get_param_or_def(const CellInfo *cell, const IdString param, int defval = 0)
 {
     auto found = cell->params.find(param);
-    if (found != cell->params.end())
+    if (found != cell->params.end()) {
         return std::stoi(found->second);
-    else
+    } else
         return defval;
 }
 
@@ -117,7 +127,7 @@ static const BelConfigPOD &get_ec_config(const ChipInfoPOD *chip, BelId bel)
 typedef std::vector<std::vector<std::vector<std::vector<int8_t>>>> chipconfig_t;
 
 static void set_ec_cbit(chipconfig_t &config, const Context *ctx, const BelConfigPOD &cell_cbits, std::string name,
-                        bool value)
+                        bool value, std::string prefix)
 {
     const ChipInfoPOD *chip = ctx->chip_info;
 
@@ -125,7 +135,7 @@ static void set_ec_cbit(chipconfig_t &config, const Context *ctx, const BelConfi
         const auto &cbit = cell_cbits.entries[i];
         if (cbit.entry_name.get() == name) {
             const auto &ti = chip->bits_info->tiles_nonrouting[tile_at(ctx, cbit.x, cbit.y)];
-            set_config(ti, config.at(cbit.y).at(cbit.x), std::string("IpConfig.") + cbit.cbit_name.get(), value);
+            set_config(ti, config.at(cbit.y).at(cbit.x), prefix + cbit.cbit_name.get(), value);
             return;
         }
     }
@@ -133,7 +143,7 @@ static void set_ec_cbit(chipconfig_t &config, const Context *ctx, const BelConfi
 }
 
 void configure_extra_cell(chipconfig_t &config, const Context *ctx, CellInfo *cell,
-                          const std::vector<std::pair<std::string, int>> &params, bool string_style)
+                          const std::vector<std::pair<std::string, int>> &params, bool string_style, std::string prefix)
 {
     const ChipInfoPOD *chip = ctx->chip_info;
     const auto &bc = get_ec_config(chip, cell->bel);
@@ -163,10 +173,10 @@ void configure_extra_cell(chipconfig_t &config, const Context *ctx, CellInfo *ce
 
         value.resize(p.second);
         if (p.second == 1) {
-            set_ec_cbit(config, ctx, bc, p.first, value.at(0));
+            set_ec_cbit(config, ctx, bc, p.first, value.at(0), prefix);
         } else {
             for (int i = 0; i < p.second; i++) {
-                set_ec_cbit(config, ctx, bc, p.first + "_" + std::to_string(i), value.at(i));
+                set_ec_cbit(config, ctx, bc, p.first + "_" + std::to_string(i), value.at(i), prefix);
             }
         }
     }
@@ -258,8 +268,13 @@ void write_asc(const Context *ctx, std::ostream &out)
             }
         }
     }
+
+    std::unordered_set<Loc> sb_io_used_by_pll;
+    std::unordered_set<Loc> sb_io_used_by_user;
+
     // Set logic cell config
     for (auto &cell : ctx->cells) {
+
         BelId bel = cell.second.get()->bel;
         if (bel == BelId()) {
             std::cout << "Found unplaced cell " << cell.first.str(ctx) << " while generating bitstream!" << std::endl;
@@ -304,6 +319,7 @@ void write_asc(const Context *ctx, std::ostream &out)
         } else if (cell.second->type == ctx->id("SB_IO")) {
             const BelInfoPOD &beli = ci.bel_data[bel.index];
             int x = beli.x, y = beli.y, z = beli.z;
+            sb_io_used_by_user.insert(Loc(x,y,z));
             const TileInfoPOD &ti = bi.tiles_nonrouting[TILE_IO];
             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"));
@@ -405,7 +421,79 @@ void write_asc(const Context *ctx, std::ostream &out)
                                                                            {"MODE_8x8", 1},
                                                                            {"A_SIGNED", 1},
                                                                            {"B_SIGNED", 1}};
-            configure_extra_cell(config, ctx, cell.second.get(), mac16_params, false);
+            configure_extra_cell(config, ctx, cell.second.get(), mac16_params, false, std::string("IpConfig."));
+        } else if (cell.second->type == ctx->id("ICESTORM_PLL")) {
+            const std::vector<std::pair<std::string, int>> pll_params = {
+                {"DELAY_ADJMODE_FB", 1}, {"DELAY_ADJMODE_REL", 1},
+                {"DIVF", 7}, {"DIVQ", 3}, {"DIVR", 4},
+                {"FDA_FEEDBACK", 4}, {"FDA_RELATIVE", 4},
+                {"FEEDBACK_PATH", 3}, {"FILTER_RANGE", 3},
+                {"PLLOUT_SELECT_A", 2}, {"PLLOUT_SELECT_B", 2},
+                {"PLLTYPE", 3}, {"SHIFTREG_DIV_MODE", 1}, {"TEST_MODE", 1}
+            };
+            configure_extra_cell(config, ctx, cell.second.get(), pll_params, false, std::string("PLL."));
+
+            // Configure the SB_IOs that the clock outputs are going through.
+            for (auto &port : cell.second->ports) {
+                // If this port is not a PLLOUT port, ignore it.
+                if (port.second.name != ctx->id("PLLOUT_A") && port.second.name != ctx->id("PLLOUT_B"))
+                    continue;
+
+                // If the output is not driving any net, ignore it.
+                if (port.second.net == nullptr)
+                    continue;
+
+                // Find SB_IO Bel in net that's driving a wire. That's the one
+                // we're routing the signal through.
+                // TODO(q3k): Is there a nicer way to do this?
+                bool found = false;
+
+                // For every wire in the PLLOUT net...
+                for (auto wp : port.second.net->wires) {
+                    // ... get its' uphill bel ...
+                    auto bel = ctx->getBelPinUphill(wp.first).bel;
+                    if (bel == BelId()) {
+                        continue;
+                    }
+                    // ... and check if it's an SB_IO.
+                    if (ctx->getBelType(bel) != TYPE_SB_IO)
+                        continue;
+
+                    // Check that this SB_IO is either unused or just used as an output.
+                    const BelInfoPOD &io_beli = ci.bel_data[bel.index];
+                    auto io_loc = Loc(io_beli.x, io_beli.y, io_beli.z);
+
+                    if (sb_io_used_by_user.count(io_loc)) {
+                        log_error("SB_IO '%s' already in use, cannot route PLL through\n",
+                                ctx->getBelName(bel).c_str(ctx));
+                    }
+                    sb_io_used_by_pll.insert(Loc(io_beli.x, io_beli.y, io_beli.z));
+
+                    // Get IE/REN config location (cf. http://www.clifford.at/icestorm/io_tile.html)
+                    auto ieren = get_ieren(bi, io_beli.x, io_beli.y, io_beli.z);
+                    int iex, iey, iez;
+                    std::tie(iex, iey, iez) = ieren;
+                    NPNR_ASSERT(iez != -1);
+
+                    // Write config.
+                    const TileInfoPOD &ti = bi.tiles_nonrouting[TILE_IO];
+                    // Enable input buffer and disable pull-up resistor in block
+                    // (this is used by the PLL).
+                    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);
+                    // PINTYPE[0] passes the PLL through to the fabric.
+                    set_config(ti, config.at(io_beli.y).at(io_beli.x), "IOB_" + std::to_string(io_beli.z) + ".PINTYPE_0", true);
+
+                    found = true;
+                    break;
+                }
+
+                if (!found) {
+                    log_error("Could not find SB_IO forwarding PLL '%s' %s signal\n",
+                            cell.second->name.c_str(ctx), port.second.name.c_str(ctx));
+                }
+            }
+
         } else {
             NPNR_ASSERT(false);
         }
@@ -416,14 +504,16 @@ void write_asc(const Context *ctx, std::ostream &out)
             const TileInfoPOD &ti = bi.tiles_nonrouting[TILE_IO];
             const BelInfoPOD &beli = ci.bel_data[bel.index];
             int x = beli.x, y = beli.y, z = beli.z;
+            if (sb_io_used_by_pll.count(Loc(x, y, z))) {
+                continue;
+            }
+
             auto ieren = get_ieren(bi, x, y, z);
             int iex, iey, iez;
             std::tie(iex, iey, iez) = ieren;
             if (iez != -1) {
-                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), true);
-                    set_config(ti, config.at(iey).at(iex), "IoCtrl.REN_" + std::to_string(iez), false);
-                }
+                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);
             }
         } else if (ctx->bel_to_cell[bel.index] == IdString() && ctx->getBelType(bel) == TYPE_ICESTORM_RAM) {
             const BelInfoPOD &beli = ci.bel_data[bel.index];
diff --git a/ice40/cells.cc b/ice40/cells.cc
index 71a65d44..3215a38c 100644
--- a/ice40/cells.cc
+++ b/ice40/cells.cc
@@ -207,6 +207,40 @@ std::unique_ptr<CellInfo> create_ice_cell(Context *ctx, IdString type, std::stri
         add_port(ctx, new_cell.get(), "ACCUMCO", PORT_OUT);
         add_port(ctx, new_cell.get(), "SIGNEXTOUT", PORT_OUT);
 
+    } else if (type == ctx->id("ICESTORM_PLL")) {
+        new_cell->params[ctx->id("DELAY_ADJMODE_FB")] = "0";
+        new_cell->params[ctx->id("DELAY_ADJMODE_REL")] = "0";
+
+        new_cell->params[ctx->id("DIVF")] = "0";
+        new_cell->params[ctx->id("DIVQ")] = "0";
+        new_cell->params[ctx->id("DIVR")] = "0";
+
+        new_cell->params[ctx->id("FDA_FEEDBACK")] = "0";
+        new_cell->params[ctx->id("FDA_RELATIVE")] = "0";
+        new_cell->params[ctx->id("FEEDBACK_PATH")] = "0";
+        new_cell->params[ctx->id("FILTER_RANGE")] = "0";
+
+        new_cell->params[ctx->id("PLLOUT_SELECT_A")] = "0";
+        new_cell->params[ctx->id("PLLOUT_SELECT_B")] = "0";
+
+        new_cell->params[ctx->id("PLLTYPE")] = "0";
+        new_cell->params[ctx->id("SHIFTREG_DIVMODE")] = "0";
+        new_cell->params[ctx->id("TEST_MODE")] = "0";
+
+        add_port(ctx, new_cell.get(), "BYPASS", PORT_IN);
+        add_port(ctx, new_cell.get(), "DYNAMICDELAY", PORT_IN);
+        add_port(ctx, new_cell.get(), "EXTFEEDBACK", PORT_IN);
+        add_port(ctx, new_cell.get(), "LATCHINPUTVALUE", PORT_IN);
+        add_port(ctx, new_cell.get(), "REFERENCECLK", PORT_IN);
+        add_port(ctx, new_cell.get(), "RESETB", PORT_IN);
+
+        add_port(ctx, new_cell.get(), "SCLK", PORT_IN);
+        add_port(ctx, new_cell.get(), "SDI", PORT_IN);
+        add_port(ctx, new_cell.get(), "SDI", PORT_OUT);
+
+        add_port(ctx, new_cell.get(), "LOCK", PORT_OUT);
+        add_port(ctx, new_cell.get(), "PLLOUT_A", PORT_OUT);
+        add_port(ctx, new_cell.get(), "PLLOUT_B", PORT_OUT);
     } else {
         log_error("unable to create iCE40 cell of type %s", type.c_str(ctx));
     }
@@ -312,6 +346,21 @@ void nxio_to_sb(Context *ctx, CellInfo *nxio, CellInfo *sbio)
     }
 }
 
+uint8_t sb_pll40_type(const BaseCtx *ctx, const CellInfo *cell)
+{
+    if (cell->type == ctx->id("SB_PLL40_PAD"))
+        return 2;
+    if (cell->type == ctx->id("SB_PLL40_2_PAD"))
+        return 4;
+    if (cell->type == ctx->id("SB_PLL40_2F_PAD"))
+        return 5;
+    if (cell->type == ctx->id("SB_PLL40_CORE"))
+        return 3;
+    if (cell->type == ctx->id("SB_PLL40_2F_CORE"))
+        return 7;
+    NPNR_ASSERT(0);
+}
+
 bool is_clock_port(const BaseCtx *ctx, const PortRef &port)
 {
     if (port.cell == nullptr)
diff --git a/ice40/cells.h b/ice40/cells.h
index 2f9c77e8..404f401c 100644
--- a/ice40/cells.h
+++ b/ice40/cells.h
@@ -71,6 +71,15 @@ inline bool is_sb_spram(const BaseCtx *ctx, const CellInfo *cell) { return cell-
 
 inline bool is_sb_mac16(const BaseCtx *ctx, const CellInfo *cell) { return cell->type == ctx->id("SB_MAC16"); }
 
+inline bool is_sb_pll40(const BaseCtx *ctx, const CellInfo *cell)
+{
+    return cell->type == ctx->id("SB_PLL40_PAD") || cell->type == ctx->id("SB_PLL40_2_PAD") ||
+           cell->type == ctx->id("SB_PLL40_2F_PAD") || cell->type == ctx->id("SB_PLL40_CORE") ||
+           cell->type == ctx->id("SB_PLL40_2F_CORE");
+}
+
+uint8_t sb_pll40_type(const BaseCtx *ctx, const CellInfo *cell);
+
 // Convert a SB_LUT primitive to (part of) an ICESTORM_LC, swapping ports
 // as needed. Set no_dff if a DFF is not being used, so that the output
 // can be reconnected
diff --git a/ice40/chipdb.py b/ice40/chipdb.py
index 0e8e3ba7..63f08e36 100644
--- a/ice40/chipdb.py
+++ b/ice40/chipdb.py
@@ -184,6 +184,8 @@ def wire_type(name):
         wt = "LOCAL"
     elif name in ("WCLK", "WCLKE", "WE", "RCLK", "RCLKE", "RE"):
         wt = "LOCAL"
+    elif name in ("PLLOUT_A", "PLLOUT_B"):
+        wt = "LOCAL"
 
     if wt is None:
         print("No type for wire: %s (%s)" % (longname, name), file=sys.stderr)
@@ -591,6 +593,43 @@ def is_ec_output(ec_entry):
     if "glb_netwk_" in wirename: return True
     return False
 
+def is_ec_pll_clock_output(ec, ec_entry):
+    return ec[0] == 'PLL' and ec_entry[0] in ('PLLOUT_A', 'PLLOUT_B')
+
+def add_pll_clock_output(bel, ec, ec_entry):
+    #print('add_pll_clock_output', ec, ec_entry)
+    pll_x, pll_y, pll_z = ec[1], ec[2], ec[3]
+    port = ec_entry[0]
+    io_x, io_y, io_z = ec_entry[1]
+    io_z = int(io_z)
+
+    global num_wires
+    wire_idx = num_wires
+    num_wires = num_wires + 1
+    
+    wire_xy[wire_idx] = [(pll_x, pll_y)]
+
+    wire_names_r[wire_idx] = (pll_x, pll_y, port)
+    wire_names[(pll_x, pll_y, port)] = wire_idx
+    wire_segments[wire_idx] = {
+        (pll_x, pll_y): port,
+        (io_x, io_y): 'PLLIN',
+    }
+
+    wire_downhill_belports[wire_idx] = {(bel, port),}
+    bel_wires[bel].append((wire_idx, port))
+
+    io_wire = wire_names[(io_x, io_y, 'io_{}/D_IN_0'.format(io_z))]
+    wire_downhill[wire_idx] = {io_wire,}
+    if io_wire not in wire_uphill:
+        wire_uphill[io_wire] = set()
+    wire_uphill[io_wire].add(wire_idx)
+
+    switches.append((io_x, io_y, 0, []))
+    switchnum = len(switches) - 1
+    pip_xy[(wire_idx, io_wire)] = (io_x, io_y, 0, switchnum)
+
+
 def add_bel_ec(ec):
     ectype, x, y, z = ec
     bel = len(bel_name)
@@ -605,6 +644,8 @@ def add_bel_ec(ec):
                 add_bel_output(bel, wire_names[entry[1]], entry[0])
             else:
                 add_bel_input(bel, wire_names[entry[1]], entry[0])
+        elif is_ec_pll_clock_output(ec, entry):
+            add_pll_clock_output(bel, ec, entry)
         else:
             extra_cell_config[bel].append(entry)
 
diff --git a/ice40/gfx.h b/ice40/gfx.h
index 8a55407d..7eeaccf1 100644
--- a/ice40/gfx.h
+++ b/ice40/gfx.h
@@ -464,7 +464,11 @@ enum GfxTileWireId
     TILE_WIRE_SP12_H_R_23,
 
     TILE_WIRE_SP12_H_L_22,
-    TILE_WIRE_SP12_H_L_23
+    TILE_WIRE_SP12_H_L_23,
+
+    TILE_WIRE_PLLIN,
+    TILE_WIRE_PLLOUT_A,
+    TILE_WIRE_PLLOUT_B
 };
 
 void gfxTileWire(std::vector<GraphicElement> &g, int x, int y, GfxTileWireId id, GraphicElement::style_t style);
diff --git a/ice40/pack.cc b/ice40/pack.cc
index 7e2e389c..f63e14f6 100644
--- a/ice40/pack.cc
+++ b/ice40/pack.cc
@@ -591,6 +591,38 @@ static void pack_special(Context *ctx)
                 replace_port(ci, ctx->id(pi.name.c_str(ctx)), packed.get(), ctx->id(newname));
             }
             new_cells.push_back(std::move(packed));
+        } else if (is_sb_pll40(ctx, ci)) {
+            std::unique_ptr<CellInfo> packed =
+                    create_ice_cell(ctx, ctx->id("ICESTORM_PLL"), ci->name.str(ctx) + "_PLL");
+            packed_cells.insert(ci->name);
+            for (auto attr : ci->attrs)
+                packed->attrs[attr.first] = attr.second;
+            for (auto param : ci->params)
+                packed->params[param.first] = param.second;
+
+            auto feedback_path = packed->params[ctx->id("FEEDBACK_PATH")];
+            packed->params[ctx->id("FEEDBACK_PATH")] = feedback_path == "DELAY" ?  "0" :
+                                                       feedback_path == "SIMPLE" ? "1" :
+                                                       feedback_path == "PHASE_AND_DELAY" ? "2" :
+                                                       feedback_path == "EXTERNAL" ? "6" : feedback_path;
+            packed->params[ctx->id("PLLTYPE")] = std::to_string(sb_pll40_type(ctx, ci));
+            
+            for (auto port : ci->ports) {
+                PortInfo &pi = port.second;
+                std::string newname = pi.name.str(ctx);
+                size_t bpos = newname.find('[');
+                if (bpos != std::string::npos) {
+                    newname = newname.substr(0, bpos) + "_" + newname.substr(bpos + 1, (newname.size() - bpos) - 2);
+                }
+                if (pi.name == ctx->id("PLLOUTCOREA"))
+                    newname = "PLLOUT_A";
+                if (pi.name == ctx->id("PLLOUTCOREB"))
+                    newname = "PLLOUT_B";
+                if (pi.name == ctx->id("PLLOUTCORE"))
+                    newname = "PLLOUT_A";
+                replace_port(ci, ctx->id(pi.name.c_str(ctx)), packed.get(), ctx->id(newname));
+            }
+            new_cells.push_back(std::move(packed));
         }
     }
 
diff --git a/ice40/pcf.cc b/ice40/pcf.cc
index ac1c8598..3d0d0d84 100644
--- a/ice40/pcf.cc
+++ b/ice40/pcf.cc
@@ -62,6 +62,31 @@ bool apply_pcf(Context *ctx, std::istream &in)
                     log_info("constrained '%s' to bel '%s'\n", cell.c_str(),
                              fnd_cell->second->attrs[ctx->id("BEL")].c_str());
                 }
+            } else if (cmd == "set_loc") {
+                size_t args_end = 1;
+                while (args_end < words.size() && words.at(args_end).at(0) == '-')
+                    args_end++;
+                std::string cell = words.at(args_end);
+                std::string x = words.at(args_end + 1);
+                std::string y = words.at(args_end + 2);
+                std::string z = words.at(args_end + 3);
+                auto fnd_cell = ctx->cells.find(ctx->id(cell));
+                if (fnd_cell == ctx->cells.end()) {
+                    log_error("unmatched pcf constraint %s\n", cell.c_str());
+                }
+
+                Loc loc;
+                loc.x = std::stoi(x);
+                loc.y = std::stoi(y);
+                loc.z = std::stoi(z);
+                auto bel = ctx->getBelByLocation(loc);
+                if (bel == BelId()) {
+                    log_error("constrain '%s': unknown bel\n", line.c_str());
+                }
+
+                fnd_cell->second->attrs[ctx->id("BEL")] = ctx->getBelName(bel).str(ctx);
+                log_info("constrained '%s' to bel '%s'\n", cell.c_str(), ctx->getBelName(bel).c_str(ctx));
+
             } else {
                 log_error("unsupported pcf command '%s'\n", cmd.c_str());
             }
diff --git a/ice40/portpins.inc b/ice40/portpins.inc
index d78625d1..f9dac887 100644
--- a/ice40/portpins.inc
+++ b/ice40/portpins.inc
@@ -118,6 +118,8 @@ X(DYNAMICDELAY_5)
 X(DYNAMICDELAY_6)
 X(DYNAMICDELAY_7)
 X(LOCK)
+X(PLLOUT_A)
+X(PLLOUT_B)
 X(BYPASS)
 X(RESETB)
 X(LATCHINPUTVALUE)