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ecp5: Use dedicated routing for ECLKs where possible

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Signed-off-by: David Shah <dave@ds0.me>
This commit is contained in:
David Shah 2020-04-14 18:55:55 +01:00
parent 96c14abd1f
commit 64d3e3e1e8
1 changed files with 80 additions and 1 deletions
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81
ecp5/globals.cc
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@ -517,8 +517,87 @@ class Ecp5GlobalRouter
route_logic_tile_global(clocks.at(user.second), user.second, *user.first);
}
}
void route_eclk_sources()
{
// Try and use dedicated paths if possible
for (auto cell : sorted(ctx->cells)) {
CellInfo *ci = cell.second;
if (ci->type == id_ECLKSYNCB || ci->type == id_TRELLIS_ECLKBUF || ci->type == id_ECLKBRIDGECS) {
std::vector<IdString> pins;
if (ci->type == id_ECLKSYNCB || ci->type == id_TRELLIS_ECLKBUF) {
pins.push_back(id_ECLKI);
} else {
pins.push_back(id_CLK0);
pins.push_back(id_CLK1);
}
for (auto pin : pins) {
NetInfo *ni = get_net_or_empty(ci, pin);
if (ni == nullptr)
continue;
log_info(" trying dedicated routing for edge clock source %s\n", ctx->nameOf(ni));
WireId src = ctx->getNetinfoSourceWire(ni);
WireId dst = ctx->getBelPinWire(ci->bel, pin);
std::queue<WireId> visit;
std::unordered_map<WireId, PipId> backtrace;
visit.push(dst);
int iter = 0;
WireId cursor;
bool success = false;
// This is a best-effort pass, if it fails then still try general routing later
const int iter_max = 1000;
while (iter < iter_max && !visit.empty()) {
cursor = visit.front();
visit.pop();
++iter;
NetInfo *bound = ctx->getBoundWireNet(cursor);
if (bound != nullptr) {
if (bound == ni) {
success = true;
break;
} else {
continue;
}
}
if (cursor == src) {
ctx->bindWire(cursor, ni, STRENGTH_LOCKED);
success = true;
break;
}
for (auto uh : ctx->getPipsUphill(cursor)) {
if (!ctx->checkPipAvail(uh))
continue;
WireId src = ctx->getPipSrcWire(uh);
if (backtrace.count(src))
continue;
IdString basename = ctx->getWireBasename(src);
// "ECLKCIB" wires are the junction with general routing
if (basename.str(ctx).find("ECLKCIB") != std::string::npos)
continue;
visit.push(src);
backtrace[src] = uh;
}
}
if (success) {
while (cursor != dst) {
PipId pip = backtrace.at(cursor);
ctx->bindPip(pip, ni, STRENGTH_LOCKED);
cursor = ctx->getPipDstWire(pip);
}
} else {
log_info(" no route found, general routing will be used.\n");
}
}
}
}
}
};
void promote_ecp5_globals(Context *ctx) { Ecp5GlobalRouter(ctx).promote_globals(); }
void route_ecp5_globals(Context *ctx) { Ecp5GlobalRouter(ctx).route_globals(); }
void route_ecp5_globals(Context *ctx)
{
Ecp5GlobalRouter router(ctx);
router.route_globals();
router.route_eclk_sources();
}
NEXTPNR_NAMESPACE_END