Add clock buffer insertion pass, improve iopadmap.

A few new attributes are defined for use in cell libraries:

- iopad_external_pin: marks PAD cell's external-facing pin.  Pad
  insertion will be skipped for ports that are already connected
  to such a pin.
- clkbuf_sink: marks an input pin as a clock pin, requesting clock
  buffer insertion.
- clkbuf_driver: marks an output pin as a clock buffer output pin.
  Clock buffer insertion will be skipped for nets that are already
  driven by such a pin.

All three are module attributes that should be set to a comma-separeted
list of pin names.

Clock buffer insertion itself works as follows:

1. All cell ports, starting from bottom up, can be marked as clock sinks
   (requesting clock buffer insertion) or as clock buffer outputs.
2. If a wire in a given module is driven by a cell port that is a clock
   buffer output, it is in turn also considered a clock buffer output.
3. If an input port in a non-top module is connected to a clock sink in a
   contained cell, it is also in turn considered a clock sink.
4. If a wire in a module is driven by a non-clock-buffer cell, and is
   also connected to a clock sink port in a contained cell, a clock
   buffer is inserted in this module.
5. For the top module, a clock buffer is also inserted on input ports
   connected to clock sinks, optionally with a special kind of input
   PAD (such as IBUFG for Xilinx).
6. Clock buffer insertion on a given wire is skipped if the clkbuf_inhibit
   attribute is set on it.

3 files changed, 356 insertions, 20 deletions

diff --git a/passes/techmap/Makefile.inc b/passes/techmap/Makefile.inc
index 56f05eca4..631a80aa5 100644
--- a/passes/techmap/Makefile.inc
+++ b/passes/techmap/Makefile.inc
@@ -16,6 +16,7 @@ endif
 
 ifneq ($(SMALL),1)
 OBJS += passes/techmap/iopadmap.o
+OBJS += passes/techmap/clkbufmap.o
 OBJS += passes/techmap/hilomap.o
 OBJS += passes/techmap/extract.o
 OBJS += passes/techmap/extract_fa.o
diff --git a/passes/techmap/clkbufmap.cc b/passes/techmap/clkbufmap.cc
new file mode 100644
index 000000000..9ecc83071
--- /dev/null
+++ b/passes/techmap/clkbufmap.cc
@@ -0,0 +1,299 @@
+/*
+ *  yosys -- Yosys Open SYnthesis Suite
+ *
+ *  Copyright (C) 2012  Clifford Wolf <clifford@clifford.at>
+ *
+ *  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 "kernel/yosys.h"
+#include "kernel/sigtools.h"
+
+USING_YOSYS_NAMESPACE
+PRIVATE_NAMESPACE_BEGIN
+
+void split_portname_pair(std::string &port1, std::string &port2)
+{
+	size_t pos = port1.find_first_of(':');
+	if (pos != std::string::npos) {
+		port2 = port1.substr(pos+1);
+		port1 = port1.substr(0, pos);
+	}
+}
+
+std::vector<std::string> split(std::string text, const char *delim)
+{
+	std::vector<std::string> list;
+	char *p = strdup(text.c_str());
+	char *t = strtok(p, delim);
+	while (t != NULL) {
+		list.push_back(t);
+		t = strtok(NULL, delim);
+	}
+	free(p);
+	return list;
+}
+
+struct ClkbufmapPass : public Pass {
+	ClkbufmapPass() : Pass("clkbufmap", "insert global buffers on clock networks") { }
+	void help() YS_OVERRIDE
+	{
+		log("\n");
+		log("    clkbufmap [options] [selection]\n");
+		log("\n");
+		log("Inserts global buffers between nets connected to clock inputs and their\n");
+		log("drivers.\n");
+		log("\n");
+		log("    -buf <celltype> <portname_out>:<portname_in>\n");
+		log("        Specifies the cell type to use for the global buffers\n");
+		log("        and its port names.  The first port will be connected to\n");
+		log("        the clock network sinks, and the second will be connected\n");
+		log("        to the actual clock source.  This option is required.\n");
+		log("\n");
+		log("    -inpad <celltype> <portname_out>:<portname_in>\n");
+		log("        If specified, a PAD cell of the given type is inserted on\n");
+		log("        clock nets that are also top module's inputs (in addition\n");
+		log("        to the global buffer).\n");
+		log("\n");
+	}
+
+	void module_queue(Design *design, Module *module, std::vector<Module *> &modules_sorted, pool<Module *> &modules_processed) {
+		if (modules_processed.count(module))
+			return;
+		for (auto cell : module->cells()) {
+			Module *submodule = design->module(cell->type);
+			if (!submodule)
+				continue;
+			module_queue(design, submodule, modules_sorted, modules_processed);
+		}
+		modules_sorted.push_back(module);
+		modules_processed.insert(module);
+	}
+
+	void execute(std::vector<std::string> args, RTLIL::Design *design) YS_OVERRIDE
+	{
+		log_header(design, "Executing CLKBUFMAP pass (inserting global clock buffers).\n");
+
+		std::string buf_celltype, buf_portname, buf_portname2;
+		std::string inpad_celltype, inpad_portname, inpad_portname2;
+
+		size_t argidx;
+		for (argidx = 1; argidx < args.size(); argidx++)
+		{
+			std::string arg = args[argidx];
+			if (arg == "-buf" && argidx+2 < args.size()) {
+				buf_celltype = args[++argidx];
+				buf_portname = args[++argidx];
+				split_portname_pair(buf_portname, buf_portname2);
+				continue;
+			}
+			if (arg == "-inpad" && argidx+2 < args.size()) {
+				inpad_celltype = args[++argidx];
+				inpad_portname = args[++argidx];
+				split_portname_pair(inpad_portname, inpad_portname2);
+				continue;
+			}
+			break;
+		}
+		extra_args(args, argidx, design);
+
+		if (buf_celltype.empty())
+			log_error("The -buf option is required.");
+
+		// Cell type, port name, bit index.
+		pool<pair<IdString, pair<IdString, int>>> sink_ports;
+		pool<pair<IdString, pair<IdString, int>>> buf_ports;
+
+		// Process submodules before module using them.
+		std::vector<Module *> modules_sorted;
+		pool<Module *> modules_processed;
+		for (auto module : design->selected_modules())
+			module_queue(design, module, modules_sorted, modules_processed);
+
+		for (auto module : modules_sorted)
+		{
+			if (module->get_blackbox_attribute()) {
+				auto it = module->attributes.find("\\clkbuf_driver");
+				if (it != module->attributes.end()) {
+					auto value = it->second.decode_string();
+					for (auto name : split(value, ",")) {
+						auto wire = module->wire(RTLIL::escape_id(name));
+						if (!wire)
+							log_error("Module %s does not have port %s.\n", log_id(module), log_id(name));
+						for (int i = 0; i < GetSize(wire); i++)
+							buf_ports.insert(make_pair(module->name, make_pair(RTLIL::escape_id(name), i)));
+					}
+				}
+				it = module->attributes.find("\\clkbuf_sink");
+				if (it != module->attributes.end()) {
+					auto value = it->second.decode_string();
+					for (auto name : split(value, ",")) {
+						auto wire = module->wire(RTLIL::escape_id(name));
+						if (!wire)
+							log_error("Module %s does not have port %s.\n", log_id(module), log_id(name));
+						for (int i = 0; i < GetSize(wire); i++)
+							sink_ports.insert(make_pair(module->name, make_pair(RTLIL::escape_id(name), i)));
+					}
+				}
+				continue;
+			}
+			pool<SigBit> sink_wire_bits;
+			pool<SigBit> buf_wire_bits;
+			pool<SigBit> driven_wire_bits;
+			SigMap sigmap(module);
+			// bit -> (buffer, buffer's input)
+			dict<SigBit, pair<Cell *, Wire *>> buffered_bits;
+
+			// First, collect nets that could use a clock buffer.
+			for (auto cell : module->cells())
+			for (auto port : cell->connections())
+			for (int i = 0; i < port.second.size(); i++)
+				if (sink_ports.count(make_pair(cell->type, make_pair(port.first, i))))
+					sink_wire_bits.insert(sigmap(port.second[i]));
+
+			// Second, collect ones that already have a clock buffer.
+			for (auto cell : module->cells())
+			for (auto port : cell->connections())
+			for (int i = 0; i < port.second.size(); i++)
+				if (buf_ports.count(make_pair(cell->type, make_pair(port.first, i))))
+					buf_wire_bits.insert(sigmap(port.second[i]));
+
+			// Collect all driven bits.
+			for (auto cell : module->cells())
+			for (auto port : cell->connections())
+				if (cell->output(port.first))
+					for (int i = 0; i < port.second.size(); i++)
+						driven_wire_bits.insert(port.second[i]);
+
+			// Insert buffers.
+			std::vector<pair<Wire *, Wire *>> input_queue;
+			for (auto wire : module->selected_wires())
+			{
+				// Should not happen.
+				if (wire->port_input && wire->port_output)
+					continue;
+				if (wire->get_bool_attribute("\\clkbuf_inhibit"))
+					continue;
+
+				pool<int> input_bits;
+
+				for (int i = 0; i < GetSize(wire); i++)
+				{
+					SigBit wire_bit(wire, i);
+					SigBit mapped_wire_bit = sigmap(wire_bit);
+					if (buf_wire_bits.count(mapped_wire_bit)) {
+						// Already buffered downstream.  If this is an output, mark it.
+						if (wire->port_output)
+							buf_ports.insert(make_pair(module->name, make_pair(wire->name, i)));
+					} else if (!sink_wire_bits.count(mapped_wire_bit)) {
+						// Nothing to do.
+					} else if (driven_wire_bits.count(wire_bit) || (wire->port_input && module->get_bool_attribute("\\top"))) {
+						// Clock network not yet buffered, driven by one of
+						// our cells or a top-level input -- buffer it.
+
+						log("Inserting %s on %s.%s[%d].\n", buf_celltype.c_str(), log_id(module), log_id(wire), i);
+						RTLIL::Cell *cell = module->addCell(NEW_ID, RTLIL::escape_id(buf_celltype));
+						Wire *iwire = module->addWire(NEW_ID);
+						cell->setPort(RTLIL::escape_id(buf_portname), mapped_wire_bit);
+						cell->setPort(RTLIL::escape_id(buf_portname2), iwire);
+						if (wire->port_input && !inpad_celltype.empty() && module->get_bool_attribute("\\top")) {
+							log("Inserting %s on %s.%s[%d].\n", inpad_celltype.c_str(), log_id(module), log_id(wire), i);
+							RTLIL::Cell *cell2 = module->addCell(NEW_ID, RTLIL::escape_id(inpad_celltype));
+							cell2->setPort(RTLIL::escape_id(inpad_portname), iwire);
+							iwire = module->addWire(NEW_ID);
+							cell2->setPort(RTLIL::escape_id(inpad_portname2), iwire);
+						}
+						buffered_bits[mapped_wire_bit] = make_pair(cell, iwire);
+
+						if (wire->port_input) {
+							input_bits.insert(i);
+						}
+					} else if (wire->port_input) {
+						// A clock input in a submodule -- mark it, let higher level
+						// worry about it.
+						if (wire->port_input)
+							sink_ports.insert(make_pair(module->name, make_pair(wire->name, i)));
+					}
+				}
+				if (!input_bits.empty()) {
+					// This is an input port and some buffers were inserted -- we need
+					// to create a new input wire and transfer attributes.
+					Wire *new_wire = module->addWire(NEW_ID, wire);
+
+					for (int i = 0; i < wire->width; i++) {
+						SigBit wire_bit(wire, i);
+						SigBit mapped_wire_bit = sigmap(wire_bit);
+						auto it = buffered_bits.find(mapped_wire_bit);
+						if (it != buffered_bits.end()) {
+
+							module->connect(it->second.second, SigSpec(new_wire, i));
+						} else {
+							module->connect(SigSpec(wire, i), SigSpec(new_wire, i));
+						}
+					}
+					input_queue.push_back(make_pair(wire, new_wire));
+				}
+			}
+
+			// Mark any newly-buffered output ports as such.
+			for (auto wire : module->selected_wires()) {
+				if (wire->port_input || !wire->port_output)
+					continue;
+				for (int i = 0; i < GetSize(wire); i++)
+				{
+					SigBit wire_bit(wire, i);
+					SigBit mapped_wire_bit = sigmap(wire_bit);
+					if (buffered_bits.count(mapped_wire_bit))
+						buf_ports.insert(make_pair(module->name, make_pair(wire->name, i)));
+				}
+			}
+
+			// Reconnect the drivers to buffer inputs.
+			for (auto cell : module->cells())
+			for (auto port : cell->connections()) {
+				if (!cell->output(port.first))
+					continue;
+				SigSpec sig = port.second;
+				bool newsig = false;
+				for (auto &bit : sig) {
+					const auto it = buffered_bits.find(sigmap(bit));
+					if (it == buffered_bits.end())
+						continue;
+					// Avoid substituting buffer's own output pin.
+					if (cell == it->second.first)
+						continue;
+					bit = it->second.second;
+					newsig = true;
+				}
+				if (newsig)
+					cell->setPort(port.first, sig);
+			}
+
+			// This has to be done last, to avoid upsetting sigmap before the port reconnections.
+			for (auto &it : input_queue) {
+				Wire *wire = it.first;
+				Wire *new_wire = it.second;
+				module->swap_names(new_wire, wire);
+				wire->attributes.clear();
+				wire->port_id = 0;
+				wire->port_input = false;
+				wire->port_output = false;
+			}
+
+			module->fixup_ports();
+		}
+	}
+} ClkbufmapPass;
+
+PRIVATE_NAMESPACE_END
diff --git a/passes/techmap/iopadmap.cc b/passes/techmap/iopadmap.cc
index efcc082d5..e3d68ab0c 100644
--- a/passes/techmap/iopadmap.cc
+++ b/passes/techmap/iopadmap.cc
@@ -32,6 +32,19 @@ void split_portname_pair(std::string &port1, std::string &port2)
 	}
 }
 
+std::vector<std::string> split(std::string text, const char *delim)
+{
+	std::vector<std::string> list;
+	char *p = strdup(text.c_str());
+	char *t = strtok(p, delim);
+	while (t != NULL) {
+		list.push_back(t);
+		t = strtok(NULL, delim);
+	}
+	free(p);
+	return list;
+}
+
 struct IopadmapPass : public Pass {
 	IopadmapPass() : Pass("iopadmap", "technology mapping of i/o pads (or buffers)") { }
 	void help() YS_OVERRIDE
@@ -64,6 +77,11 @@ struct IopadmapPass : public Pass {
 		log("        of the tristate driver and the 2nd portname is the internal output\n");
 		log("        buffering the external signal.\n");
 		log("\n");
+		log("    -ignore <celltype> <portname>[:<portname>]*\n");
+		log("        Skips mapping inputs/outputs that are already connected to given\n");
+		log("        ports of the given cell.  Can be used multiple times.  This is in\n");
+		log("        addition to the cells specified as mapping targets.\n");
+		log("\n");
 		log("    -widthparam <param_name>\n");
 		log("        Use the specified parameter name to set the port width.\n");
 		log("\n");
@@ -88,6 +106,7 @@ struct IopadmapPass : public Pass {
 		std::string toutpad_celltype, toutpad_portname, toutpad_portname2, toutpad_portname3;
 		std::string tinoutpad_celltype, tinoutpad_portname, tinoutpad_portname2, tinoutpad_portname3, tinoutpad_portname4;
 		std::string widthparam, nameparam;
+		pool<pair<IdString, IdString>> ignore;
 		bool flag_bits = false;
 
 		size_t argidx;
@@ -127,6 +146,18 @@ struct IopadmapPass : public Pass {
 				split_portname_pair(tinoutpad_portname3, tinoutpad_portname4);
 				continue;
 			}
+			if (arg == "-ignore" && argidx+2 < args.size()) {
+				std::string ignore_celltype = args[++argidx];
+				std::string ignore_portname = args[++argidx];
+				std::string ignore_portname2;
+				while (!ignore_portname.empty()) {
+					split_portname_pair(ignore_portname, ignore_portname2);
+					ignore.insert(make_pair(RTLIL::escape_id(ignore_celltype), RTLIL::escape_id(ignore_portname)));
+
+					ignore_portname = ignore_portname2;
+				}
+				continue;
+			}
 			if (arg == "-widthparam" && argidx+1 < args.size()) {
 				widthparam = args[++argidx];
 				continue;
@@ -143,6 +174,28 @@ struct IopadmapPass : public Pass {
 		}
 		extra_args(args, argidx, design);
 
+		if (!inpad_portname2.empty())
+			ignore.insert(make_pair(RTLIL::escape_id(inpad_celltype), RTLIL::escape_id(inpad_portname2)));
+		if (!outpad_portname2.empty())
+			ignore.insert(make_pair(RTLIL::escape_id(outpad_celltype), RTLIL::escape_id(outpad_portname2)));
+		if (!inoutpad_portname2.empty())
+			ignore.insert(make_pair(RTLIL::escape_id(inoutpad_celltype), RTLIL::escape_id(inoutpad_portname2)));
+		if (!toutpad_portname3.empty())
+			ignore.insert(make_pair(RTLIL::escape_id(toutpad_celltype), RTLIL::escape_id(toutpad_portname3)));
+		if (!tinoutpad_portname4.empty())
+			ignore.insert(make_pair(RTLIL::escape_id(tinoutpad_celltype), RTLIL::escape_id(tinoutpad_portname4)));
+
+		for (auto module : design->modules())
+		{
+			auto it = module->attributes.find("\\iopad_external_pin");
+			if (it != module->attributes.end()) {
+				auto value = it->second.decode_string();
+				for (auto name : split(value, ",")) {
+					ignore.insert(make_pair(module->name, RTLIL::escape_id(name)));
+				}
+			}
+		}
+
 		for (auto module : design->selected_modules())
 		{
 			dict<IdString, pool<int>> skip_wires;
@@ -150,28 +203,11 @@ struct IopadmapPass : public Pass {
 			SigMap sigmap(module);
 
 			for (auto cell : module->cells())
-			{
-				if (cell->type == RTLIL::escape_id(inpad_celltype) && cell->hasPort(RTLIL::escape_id(inpad_portname2)))
-					for (auto bit : sigmap(cell->getPort(RTLIL::escape_id(inpad_portname2))))
-						skip_wire_bits.insert(bit);
-
-				if (cell->type == RTLIL::escape_id(outpad_celltype) && cell->hasPort(RTLIL::escape_id(outpad_portname2)))
-					for (auto bit : sigmap(cell->getPort(RTLIL::escape_id(outpad_portname2))))
-						skip_wire_bits.insert(bit);
-
-				if (cell->type == RTLIL::escape_id(inoutpad_celltype) && cell->hasPort(RTLIL::escape_id(inoutpad_portname2)))
-					for (auto bit : sigmap(cell->getPort(RTLIL::escape_id(inoutpad_portname2))))
+			for (auto port : cell->connections())
+				if (ignore.count(make_pair(cell->type, port.first)))
+					for (auto bit : sigmap(port.second))
 						skip_wire_bits.insert(bit);
 
-				if (cell->type == RTLIL::escape_id(toutpad_celltype) && cell->hasPort(RTLIL::escape_id(toutpad_portname3)))
-					for (auto bit : sigmap(cell->getPort(RTLIL::escape_id(toutpad_portname3))))
-						skip_wire_bits.insert(bit);
-
-				if (cell->type == RTLIL::escape_id(tinoutpad_celltype) && cell->hasPort(RTLIL::escape_id(tinoutpad_portname4)))
-					for (auto bit : sigmap(cell->getPort(RTLIL::escape_id(tinoutpad_portname4))))
-						skip_wire_bits.insert(bit);
-			}
-
 			if (!toutpad_celltype.empty() || !tinoutpad_celltype.empty())
 			{
 				dict<SigBit, pair<IdString, pool<IdString>>> tbuf_bits;