mistral: Add a basic global clock router
Signed-off-by: gatecat <gatecat@ds0.me>
This commit is contained in:
gatecat
myrtle
parent
ca2e328a5f
commit
bc7b8b63ed
@ -484,6 +484,8 @@ bool Arch::route()
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lab_pre_route();
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route_globals();
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std::string router = str_or_default(settings, id_router, defaultRouter);
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bool result;
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if (router == "router1") {
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@ -503,6 +503,7 @@ struct Arch : BaseArch<ArchRanges>
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// -------------------------------------------------
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bool is_clkbuf_cell(IdString cell_type) const; // globals.cc
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void route_globals(); // globals.cc
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// -------------------------------------------------
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@ -21,6 +21,8 @@
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#include "nextpnr.h"
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#include "util.h"
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#include <queue>
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NEXTPNR_NAMESPACE_BEGIN
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void Arch::create_clkbuf(int x, int y)
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@ -60,4 +62,151 @@ void Arch::create_control(int x, int y)
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add_bel_pin(oscillator_bel, id_clkout1, PORT_OUT, get_port(CycloneV::CTRL, x, y, -1, CycloneV::CLK_OUT1, -1));
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}
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struct MistralGlobalRouter
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{
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Context *ctx;
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MistralGlobalRouter(Context *ctx) : ctx(ctx){};
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// When routing globals; we allow global->local for some tricky cases but never local->local
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bool global_pip_filter(PipId pip) const
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{
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auto src_type = CycloneV::rn2t(pip.src);
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return src_type != CycloneV::H14 && src_type != CycloneV::H6 && src_type != CycloneV::H3 &&
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src_type != CycloneV::V12 && src_type != CycloneV::V2 && src_type != CycloneV::V4 &&
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src_type != CycloneV::WM;
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}
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// Dedicated backwards BFS routing for global networks
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template <typename Tfilt>
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bool backwards_bfs_route(NetInfo *net, store_index<PortRef> user_idx, int iter_limit, bool strict, Tfilt pip_filter)
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{
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// Queue of wires to visit
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std::queue<WireId> visit;
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// Wire -> upstream pip
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dict<WireId, PipId> backtrace;
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// Lookup source and destination wires
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WireId src = ctx->getNetinfoSourceWire(net);
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WireId dst = ctx->getNetinfoSinkWire(net, net->users.at(user_idx), 0);
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if (src == WireId())
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log_error("Net '%s' has an invalid source port %s.%s\n", ctx->nameOf(net), ctx->nameOf(net->driver.cell),
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ctx->nameOf(net->driver.port));
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if (dst == WireId())
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log_error("Net '%s' has an invalid sink port %s.%s\n", ctx->nameOf(net),
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ctx->nameOf(net->users.at(user_idx).cell), ctx->nameOf(net->users.at(user_idx).port));
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if (ctx->getBoundWireNet(src) != net)
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ctx->bindWire(src, net, STRENGTH_LOCKED);
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if (src == dst) {
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// Nothing more to do
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return true;
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}
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visit.push(dst);
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backtrace[dst] = PipId();
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int iter = 0;
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while (!visit.empty() && (iter++ < iter_limit)) {
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WireId cursor = visit.front();
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visit.pop();
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// Search uphill pips
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for (PipId pip : ctx->getPipsUphill(cursor)) {
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// Skip pip if unavailable, and not because it's already used for this net
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if (!ctx->checkPipAvail(pip) && ctx->getBoundPipNet(pip) != net)
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continue;
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WireId prev = ctx->getPipSrcWire(pip);
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// Ditto for the upstream wire
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if (!ctx->checkWireAvail(prev) && ctx->getBoundWireNet(prev) != net)
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continue;
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// Skip already visited wires
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if (backtrace.count(prev))
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continue;
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// Apply our custom pip filter
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if (!pip_filter(pip))
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continue;
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// Add to the queue
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visit.push(prev);
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backtrace[prev] = pip;
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// Check if we are done yet
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if (prev == src)
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goto done;
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}
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if (false) {
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done:
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break;
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}
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}
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if (backtrace.count(src)) {
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WireId cursor = src;
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std::vector<PipId> pips;
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// Create a list of pips on the routed path
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while (true) {
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PipId pip = backtrace.at(cursor);
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if (pip == PipId())
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break;
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pips.push_back(pip);
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cursor = ctx->getPipDstWire(pip);
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}
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// Reverse that list
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std::reverse(pips.begin(), pips.end());
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// Bind pips until we hit already-bound routing
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for (PipId pip : pips) {
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WireId dst = ctx->getPipDstWire(pip);
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if (ctx->getBoundWireNet(dst) == net)
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break;
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ctx->bindPip(pip, net, STRENGTH_LOCKED);
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}
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return true;
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} else {
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if (strict)
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log_error("Failed to route net '%s' from %s to %s using dedicated routing.\n", ctx->nameOf(net),
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ctx->nameOfWire(src), ctx->nameOfWire(dst));
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return false;
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}
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}
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bool is_relaxed_sink(const PortRef &sink) const
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{
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// Cases where global clocks are driving fabric
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if (sink.cell->type == id_MISTRAL_FF && sink.port != id_CLK)
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return true;
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return false;
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}
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void route_clk_net(NetInfo *net)
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{
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for (auto usr : net->users.enumerate())
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backwards_bfs_route(net, usr.index, 1000000, true,
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[&](PipId pip) { return (is_relaxed_sink(usr.value) || global_pip_filter(pip)); });
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log_info(" routed net '%s' using global resources\n", ctx->nameOf(net));
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}
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void operator()()
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{
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log_info("Routing globals...\n");
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for (auto &net : ctx->nets) {
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NetInfo *ni = net.second.get();
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CellInfo *drv = ni->driver.cell;
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if (drv == nullptr)
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continue;
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if (drv->type.in(id_MISTRAL_CLKENA, id_MISTRAL_CLKBUF)) {
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route_clk_net(ni);
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continue;
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}
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}
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}
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};
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void Arch::route_globals()
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{
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MistralGlobalRouter router(getCtx());
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router();
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}
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NEXTPNR_NAMESPACE_END
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