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iopadmap: Emit tristate buffers with const OE for some edge cases.

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This commit is contained in:
Marcin Kościelnicki 2019-12-22 01:08:56 +01:00
parent 13a3041030
commit a24596def3
2 changed files with 88 additions and 20 deletions
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85
passes/techmap/iopadmap.cc
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@ -192,11 +192,28 @@ struct IopadmapPass : public Pass {
if (!toutpad_celltype.empty() || !tinoutpad_celltype.empty())
{
dict<SigBit, Cell *> tbuf_bits;
pool<SigBit> driven_bits;
// Gather tristate buffers and always-on drivers.
for (auto cell : module->cells())
if (cell->type == ID($_TBUF_)) {
SigBit bit = cell->getPort(ID::Y).as_bit();
tbuf_bits[bit] = cell;
} else {
for (auto port : cell->connections())
if (!cell->known() || cell->output(port.first))
for (auto bit : port.second)
driven_bits.insert(bit);
}
// If a wire is a target of an assignment, it is driven, unless the source is 'z.
for (auto &conn : module->connections())
for (int i = 0; i < GetSize(conn.first); i++) {
SigBit dstbit = conn.first[i];
SigBit srcbit = conn.second[i];
if (!srcbit.wire && srcbit.data == State::Sz)
continue;
driven_bits.insert(dstbit);
}
for (auto wire : module->selected_wires())
@ -204,41 +221,68 @@ struct IopadmapPass : public Pass {
if (!wire->port_output)
continue;
// Don't handle inout ports if we have no suitable buffer type.
if (wire->port_input && tinoutpad_celltype.empty())
continue;
// likewise for output ports.
if (!wire->port_input && toutpad_celltype.empty())
continue;
for (int i = 0; i < GetSize(wire); i++)
{
SigBit wire_bit(wire, i);
Cell *tbuf_cell = nullptr;
if (tbuf_bits.count(wire_bit) == 0)
continue;
if (tbuf_bits.count(wire_bit))
tbuf_cell = tbuf_bits.at(wire_bit);
Cell *tbuf_cell = tbuf_bits.at(wire_bit);
SigBit en_sig;
SigBit data_sig;
bool is_driven = driven_bits.count(wire_bit);
if (tbuf_cell == nullptr)
continue;
if (tbuf_cell != nullptr) {
// Found a tristate buffer — use it.
en_sig = tbuf_cell->getPort(ID(E)).as_bit();
data_sig = tbuf_cell->getPort(ID::A).as_bit();
} else if (is_driven) {
// No tristate buffer, but an always-on driver is present.
// If this is an inout port, we're creating a tinoutpad
// anyway, just with a constant 1 as enable.
if (!wire->port_input)
continue;
en_sig = SigBit(State::S1);
data_sig = wire_bit;
} else {
// No driver on a wire. Create a tristate pad with always-0
// enable.
en_sig = SigBit(State::S0);
data_sig = SigBit(State::Sx);
}
SigBit en_sig = tbuf_cell->getPort(ID(E)).as_bit();
SigBit data_sig = tbuf_cell->getPort(ID::A).as_bit();
if (wire->port_input && !tinoutpad_celltype.empty())
if (wire->port_input)
{
log("Mapping port %s.%s[%d] using %s.\n", log_id(module), log_id(wire), i, tinoutpad_celltype.c_str());
Cell *cell = module->addCell(NEW_ID, RTLIL::escape_id(tinoutpad_celltype));
cell->setPort(RTLIL::escape_id(tinoutpad_portname_oe), en_sig);
cell->setPort(RTLIL::escape_id(tinoutpad_portname_o), wire_bit);
cell->setPort(RTLIL::escape_id(tinoutpad_portname_i), data_sig);
cell->attributes[ID::keep] = RTLIL::Const(1);
module->remove(tbuf_cell);
if (tbuf_cell) {
module->remove(tbuf_cell);
cell->setPort(RTLIL::escape_id(tinoutpad_portname_o), wire_bit);
cell->setPort(RTLIL::escape_id(tinoutpad_portname_i), data_sig);
} else if (is_driven) {
cell->setPort(RTLIL::escape_id(tinoutpad_portname_i), wire_bit);
} else {
cell->setPort(RTLIL::escape_id(tinoutpad_portname_o), wire_bit);
cell->setPort(RTLIL::escape_id(tinoutpad_portname_i), data_sig);
}
skip_wire_bits.insert(wire_bit);
if (!tinoutpad_portname_pad.empty())
rewrite_bits[wire][i] = make_pair(cell, RTLIL::escape_id(tinoutpad_portname_pad));
continue;
}
if (!wire->port_input && !toutpad_celltype.empty())
{
} else {
log("Mapping port %s.%s[%d] using %s.\n", log_id(module), log_id(wire), i, toutpad_celltype.c_str());
Cell *cell = module->addCell(NEW_ID, RTLIL::escape_id(toutpad_celltype));
@ -247,12 +291,13 @@ struct IopadmapPass : public Pass {
cell->setPort(RTLIL::escape_id(toutpad_portname_i), data_sig);
cell->attributes[ID::keep] = RTLIL::Const(1);
module->remove(tbuf_cell);
module->connect(wire_bit, data_sig);
if (tbuf_cell) {
module->remove(tbuf_cell);
module->connect(wire_bit, data_sig);
}
skip_wire_bits.insert(wire_bit);
if (!toutpad_portname_pad.empty())
rewrite_bits[wire][i] = make_pair(cell, RTLIL::escape_id(toutpad_portname_pad));
continue;
}
}
}