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Gowin. BUGFIX. Global clock routing. (#1410)
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Adds additional restrictions on the first PIP after the clock source -
only connections to SPINEs are allowed. This allowed to correct the
behaviour of DQCEs since the latter can only disable/enable SPINEs.

Signed-off-by: YRabbit <[email protected]>
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@yrabbit
yrabbit authored Dec 31, 2024
1 parent f01465f commit 3d350c2
Showing 1 changed file with 38 additions and 20 deletions.
58 changes: 38 additions & 20 deletions himbaechel/uarch/gowin/globals.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -43,7 +43,7 @@ struct GowinGlobalRouter
bool global_pip_available(PipId pip) const { return gwu.is_global_pip(pip) || ctx->checkPipAvail(pip); };

// allow io->global, global->global and global->tile clock
bool global_pip_filter(PipId pip) const
bool global_pip_filter(PipId pip, WireId src_wire) const
{
auto is_local = [&](IdString wire_type) {
return !wire_type.in(id_GLOBAL_CLK, id_IO_O, id_IO_I, id_PLL_O, id_PLL_I, id_TILE_CLK);
Expand All @@ -58,7 +58,13 @@ struct GowinGlobalRouter
bool src_valid = not_dsc_pip && src_type.in(id_GLOBAL_CLK, id_IO_O, id_PLL_O, id_HCLK);
bool dst_valid = not_dsc_pip && dst_type.in(id_GLOBAL_CLK, id_TILE_CLK, id_PLL_I, id_IO_I, id_HCLK);

bool res = (src_valid && dst_valid) || (src_valid && is_local(dst_type)) || (is_local(src_type) && dst_valid);
bool res;
if (src == src_wire && (!src_type.in(id_IO, id_HCLK))) {
bool dst_is_spine = dst_name.str(ctx).rfind("SPINE", 0) == 0;
res = src_valid && dst_is_spine;
} else {
res = (src_valid && dst_valid) || (src_valid && is_local(dst_type)) || (is_local(src_type) && dst_valid);
}
if (ctx->debug && false /*&& res*/) {
log_info("%s <- %s [%s <- %s]\n", ctx->getWireName(ctx->getPipDstWire(pip)).str(ctx).c_str(),
ctx->getWireName(ctx->getPipSrcWire(pip)).str(ctx).c_str(), dst_type.c_str(ctx),
Expand All @@ -69,7 +75,7 @@ struct GowinGlobalRouter
return res;
}

bool global_DQCE_pip_filter(PipId pip) const
bool global_DQCE_pip_filter(PipId pip, WireId src_wire) const
{
auto is_local = [&](IdString wire_type) {
return !wire_type.in(id_GLOBAL_CLK, id_IO_O, id_IO_I, id_PLL_O, id_PLL_I, id_TILE_CLK);
Expand All @@ -92,18 +98,25 @@ struct GowinGlobalRouter
bool src_valid = not_dsc_pip && src_type.in(id_GLOBAL_CLK, id_IO_O, id_PLL_O, id_HCLK);
bool dst_valid = not_dsc_pip && dst_type.in(id_GLOBAL_CLK, id_TILE_CLK, id_PLL_I, id_IO_I, id_HCLK);

bool res = (src_valid && dst_valid) || (src_valid && is_local(dst_type)) || (is_local(src_type) && dst_valid);
if (ctx->debug && false /*&& res*/) {
log_info("%s <- %s [%s <- %s]\n", ctx->getWireName(ctx->getPipDstWire(pip)).str(ctx).c_str(),
ctx->getWireName(ctx->getPipSrcWire(pip)).str(ctx).c_str(), dst_type.c_str(ctx),
src_type.c_str(ctx));
log_info("res:%d, src_valid:%d, dst_valid:%d, src local:%d, dst local:%d\n", res, src_valid, dst_valid,
is_local(src_type), is_local(dst_type));
// If DQCE is used, then the source can only connect to SPINEs as only they can be switched off/on.
bool res;
if (src == src_wire) {
bool dst_is_spine = dst_name.str(ctx).rfind("SPINE", 0) == 0;
res = src_valid && dst_is_spine;
} else {
res = (src_valid && dst_valid) || (src_valid && is_local(dst_type)) || (is_local(src_type) && dst_valid);
if (ctx->debug && false /*res*/) {
log_info("%s <- %s [%s <- %s]\n", ctx->getWireName(ctx->getPipDstWire(pip)).str(ctx).c_str(),
ctx->getWireName(ctx->getPipSrcWire(pip)).str(ctx).c_str(), dst_type.c_str(ctx),
src_type.c_str(ctx));
log_info("res:%d, src_valid:%d, dst_valid:%d, src local:%d, dst local:%d\n", res, src_valid, dst_valid,
is_local(src_type), is_local(dst_type));
}
}
return res;
}

bool global_DCS_pip_filter(PipId pip) const
bool global_DCS_pip_filter(PipId pip, WireId src_wire) const
{
auto is_local = [&](IdString wire_type) {
return !wire_type.in(id_GLOBAL_CLK, id_IO_O, id_IO_I, id_PLL_O, id_PLL_I, id_TILE_CLK);
Expand Down Expand Up @@ -171,7 +184,7 @@ struct GowinGlobalRouter
continue;
}
// Apply our custom pip filter
if (!pip_filter(pip)) {
if (!pip_filter(pip, src)) {
continue;
}
// Add to the queue
Expand Down Expand Up @@ -305,8 +318,8 @@ struct GowinGlobalRouter
}
bool bfs_res;
bfs_res = backwards_bfs_route(
net, src, dst, 1000000, false, [&](PipId pip) { return (is_relaxed_sink(usr) || pip_filter(pip)); },
path);
net, src, dst, 1000000, false,
[&](PipId pip, WireId src_wire) { return (is_relaxed_sink(usr) || pip_filter(pip, src)); }, path);
if (bfs_res) {
routed = routed == ROUTED_PARTIALLY ? routed : ROUTED_ALL;
} else {
Expand Down Expand Up @@ -340,7 +353,8 @@ struct GowinGlobalRouter
src = ctx->getBelPinWire(driver.cell->bel, driver.port);
}

RouteResult route_result = route_direct_net(net, [&](PipId pip) { return global_DQCE_pip_filter(pip); }, src);
RouteResult route_result = route_direct_net(
net, [&](PipId pip, WireId src_wire) { return global_DQCE_pip_filter(pip, src); }, src);
if (route_result == NOT_ROUTED) {
log_error("Can't route the %s network.\n", ctx->nameOf(net));
}
Expand Down Expand Up @@ -417,7 +431,8 @@ struct GowinGlobalRouter
src = ctx->getBelPinWire(driver.cell->bel, driver.port);
}

RouteResult route_result = route_direct_net(net, [&](PipId pip) { return global_DCS_pip_filter(pip); }, src);
RouteResult route_result =
route_direct_net(net, [&](PipId pip, WireId src_wire) { return global_DCS_pip_filter(pip, src); }, src);
if (route_result == NOT_ROUTED) {
log_error("Can't route the %s network.\n", ctx->nameOf(net));
}
Expand Down Expand Up @@ -504,7 +519,8 @@ struct GowinGlobalRouter
WireId src = ctx->getBelPinWire(driver.cell->bel, port);

std::vector<PipId> path;
RouteResult route_result = route_direct_net(net, [&](PipId pip) { return global_pip_filter(pip); }, src, &path);
RouteResult route_result = route_direct_net(
net, [&](PipId pip, WireId src_wire) { return global_pip_filter(pip, src); }, src, &path);
if (route_result == NOT_ROUTED) {
log_error("Can't route the %s network.\n", ctx->nameOf(net));
}
Expand Down Expand Up @@ -568,7 +584,8 @@ struct GowinGlobalRouter
NetInfo *net_before_buf = buf_ci->getPort(id_I);
NPNR_ASSERT(net_before_buf != nullptr);

RouteResult route_result = route_direct_net(net, [&](PipId pip) { return global_pip_filter(pip); }, src);
RouteResult route_result = route_direct_net(
net, [&](PipId pip, WireId src_wire) { return global_pip_filter(pip, src_wire); }, src);
if (route_result == NOT_ROUTED || route_result == ROUTED_PARTIALLY) {
log_error("Can't route the %s net. It might be worth removing the BUFG buffer flag.\n", ctx->nameOf(net));
}
Expand All @@ -578,7 +595,7 @@ struct GowinGlobalRouter
CellInfo *true_src_ci = net_before_buf->driver.cell;
src = ctx->getBelPinWire(true_src_ci->bel, net_before_buf->driver.port);
ctx->bindWire(src, net, STRENGTH_LOCKED);
backwards_bfs_route(net, src, dst, 1000000, false, [&](PipId pip) { return true; });
backwards_bfs_route(net, src, dst, 1000000, false, [&](PipId pip, WireId src_wire) { return true; });
// remove net
buf_ci->movePortTo(id_O, true_src_ci, net_before_buf->driver.port);
net_before_buf->driver.cell = nullptr;
Expand All @@ -588,7 +605,8 @@ struct GowinGlobalRouter

void route_clk_net(NetInfo *net)
{
RouteResult route_result = route_direct_net(net, [&](PipId pip) { return global_pip_filter(pip); });
RouteResult route_result =
route_direct_net(net, [&](PipId pip, WireId src_wire) { return global_pip_filter(pip, src_wire); });
if (route_result != NOT_ROUTED) {
log_info(" '%s' net was routed using global resources %s.\n", ctx->nameOf(net),
route_result == ROUTED_ALL ? "only" : "partially");
Expand Down

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