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nexus: Add constant/inversion packing

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Signed-off-by: David Shah <dave@ds0.me>
This commit is contained in:
David Shah 2020-10-13 14:15:29 +01:00
parent 1bb509897c
commit da1e3c8612
4 changed files with 79 additions and 18 deletions
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8
nexus/arch.h
View File

@ -785,17 +785,19 @@ enum CellPinStyle
PINBIT_GATED = 0x1000, // pin must be enabled in bitstream if used
PINBIT_1 = 0x2000, // pin has an explicit bit that must be set if tied to 1
PINBIT_CIBMUX = 0x4000, // pin's CIBMUX must be floating for pin to be 1
PINSTYLE_NONE = 0x0000, // default
PINSTYLE_CIB = 0x0012, // 'CIB' signal, floats high but explicitly zeroed if not used
PINSTYLE_CIB = 0x4012, // 'CIB' signal, floats high but explicitly zeroed if not used
PINSTYLE_CLK = 0x0107, // CLK type signal, invertible and defaults to disconnected
PINSTYLE_CE = 0x0027, // CE type signal, invertible and defaults to enabled
PINSTYLE_LSR = 0x0017, // LSR type signal, invertible and defaults to not reset
PINSTYLE_DEDI = 0x0000, // dedicated signals, leave alone
PINSTYLE_PU = 0x0022, // signals that float high and default high
PINSTYLE_PU = 0x4022, // signals that float high and default high
PINSTYLE_T = 0x4027, // PIO 'T' signal
PINSTYLE_INV_PD = 0x0017, // invertible, pull down by default
PINSTYLE_INV_PU = 0x0027, // invertible, pull up by default
PINSTYLE_INV_PU = 0x4027, // invertible, pull up by default
PINSTYLE_IOL_CE = 0x2027, // CE type signal, with explicit 'const-1' config bit
PINSTYLE_GATE = 0x1011, // gated signal that defaults to 0

47
nexus/fasm.cc
View File

@ -170,7 +170,7 @@ struct NexusFasmWriter
std::string tile = tile_name(pip.tile, tile_by_type_and_loc(pip.tile, pd.tile_type));
std::string source_wire = escape_name(ctx->pip_src_wire_name(pip).str(ctx));
std::string dest_wire = escape_name(ctx->pip_dst_wire_name(pip).str(ctx));
write_bit(stringf("%s.PIP.%s.%s", tile.c_str(), dest_wire.c_str(), source_wire.c_str()));
out << stringf("%s.PIP.%s.%s", tile.c_str(), dest_wire.c_str(), source_wire.c_str()) << std::endl;
}
// Write out all the pips corresponding to a net
void write_net(const NetInfo *net)
@ -184,6 +184,25 @@ struct NexusFasmWriter
write_pip(p);
blank();
}
// Find the CIBMUX output for a signal
WireId find_cibmux(const CellInfo *cell, IdString pin)
{
WireId cursor = ctx->getBelPinWire(cell->bel, pin);
if (cursor == WireId())
return WireId();
for (int i = 0; i < 10; i++) {
std::string cursor_name = IdString(ctx->wire_data(cursor).name).str(ctx);
if (cursor_name.find("JCIBMUXOUT") == 0) {
return cursor;
}
for (PipId pip : ctx->getPipsUphill(cursor))
if (ctx->checkPipAvail(pip)) {
cursor = ctx->getPipSrcWire(pip);
break;
}
}
return WireId();
}
// Write out the mux config for a cell
void write_cell_muxes(const CellInfo *cell)
{
@ -206,8 +225,26 @@ struct NexusFasmWriter
// Pins that must be explictly set to 1 rather than just left floating
if ((pin_style & PINBIT_1) && (pin_mux == PINMUX_1))
write_bit(stringf("%sMUX.1", ctx->nameOf(port.first)));
// Handle CIB muxes - these must be set such that floating pins really are floating to VCC and not connected
// to another CIB signal
if ((pin_style & PINBIT_CIBMUX) && port.second.net == nullptr) {
WireId cibmuxout = find_cibmux(cell, port.first);
if (cibmuxout != WireId()) {
write_comment(stringf("CIBMUX for unused pin %s", ctx->nameOf(port.first)));
bool found = false;
for (PipId pip : ctx->getPipsUphill(cibmuxout)) {
if (ctx->checkPipAvail(pip) && ctx->checkWireAvail(ctx->getPipSrcWire(pip))) {
write_pip(pip);
found = true;
break;
}
}
NPNR_ASSERT(found);
}
}
}
}
// Write config for an OXIDE_COMB cell
void write_comb(const CellInfo *cell)
{
@ -244,10 +281,7 @@ struct NexusFasmWriter
pop();
write_enum(cell, "REGDDR");
write_enum(cell, "SRMODE");
write_enum(cell, "CLKMUX");
write_enum(cell, "CEMUX");
write_enum(cell, "LSRMUX");
write_enum(cell, "GSR");
write_cell_muxes(cell);
pop(2);
}
// Write config for an SEIO33_CORE cell
@ -267,6 +301,7 @@ struct NexusFasmWriter
const char *iodir = is_input ? "INPUT" : (is_output ? "OUTPUT" : "BIDIR");
write_bit(stringf("BASE_TYPE.%s_%s", iodir, str_or_default(cell->attrs, id_IO_TYPE, "LVCMOS33").c_str()));
write_ioattr(cell, "PULLMODE", "NONE");
write_cell_muxes(cell);
pop(2);
}
// Write config for an SEIO18_CORE cell
@ -287,6 +322,7 @@ struct NexusFasmWriter
const char *iodir = is_input ? "INPUT" : (is_output ? "OUTPUT" : "BIDIR");
write_bit(stringf("BASE_TYPE.%s_%s", iodir, str_or_default(cell->attrs, id_IO_TYPE, "LVCMOS18H").c_str()));
write_ioattr(cell, "PULLMODE", "NONE");
write_cell_muxes(cell);
pop(3);
}
// Write config for an OSC_CORE cell
@ -302,6 +338,7 @@ struct NexusFasmWriter
write_enum(cell, "LF_OUTPUT_EN");
write_enum(cell, "DEBUG_N", "DISABLED");
write_int_vector(stringf("HF_CLK_DIV[7:0]"), ctx->parse_lattice_param(cell, id_HF_CLK_DIV, 8, 0).intval, 8);
write_cell_muxes(cell);
pop(2);
}
// Write out FASM for the whole design

30
nexus/pack.cc
View File

@ -321,7 +321,12 @@ struct NexusPacker
{
NetInfo *net = get_net_or_empty(cell, port);
if (net == nullptr || net->driver.cell == nullptr) {
// Pin is disconnected, return its default value
// Pin is disconnected
// If a mux value exists already, honour it
CellPinMux exist_mux = ctx->get_cell_pinmux(cell, port);
if (exist_mux != PINMUX_SIG)
return exist_mux;
// Otherwise, look up the default value and use that
CellPinStyle pin_style = ctx->get_cell_pin_style(cell, port);
if ((pin_style & PINDEF_MASK) == PINDEF_0)
return PINMUX_0;
@ -434,7 +439,7 @@ struct NexusPacker
if (req_mux == PINMUX_INV) {
// Pin is inverted. If there is a hard inverter; then use it
if ((pin_style & PINOPT_MASK) == PINOPT_INV) {
if (pin_style & PINOPT_INV) {
uninvert_port(cell, port_name);
ctx->set_cell_pinmux(cell, port_name, PINMUX_INV);
}
@ -624,13 +629,30 @@ struct NexusPacker
}
}
void pack_constants()
{
// Make sure we have high and low nets available
get_const_net(id_VHI);
get_const_net(id_VLO);
// Iterate through cells
for (auto cell : sorted(ctx->cells)) {
CellInfo *ci = cell.second;
// Skip certain cells at this point
if (ci->type != id_LUT4 && ci->type != id_INV && ci->type != id_VHI && ci->type != id_VLO)
process_inv_constants(cell.second);
}
// Remove superfluous inverters and constant drivers
trim_design();
}
explicit NexusPacker(Context *ctx) : ctx(ctx) {}
void operator()()
{
pack_ffs();
pack_luts();
pack_io();
pack_ffs();
pack_constants();
pack_luts();
}
};

8
nexus/pins.cc
View File

@ -48,15 +48,15 @@ static const std::unordered_map<IdString, Arch::CellPinsData> base_cell_pin_data
}},
{id_SEIO18_CORE,
{
{id_T, PINSTYLE_CE},
{id_T, PINSTYLE_T},
{id_B, PINSTYLE_DEDI},
{{}, PINSTYLE_INV_PU},
{{}, PINSTYLE_PU},
}},
{id_SEIO33_CORE,
{
{id_T, PINSTYLE_CE},
{id_T, PINSTYLE_T},
{id_B, PINSTYLE_DEDI},
{{}, PINSTYLE_INV_PU},
{{}, PINSTYLE_PU},
}},
{id_OXIDE_EBR, {{id_CLKA, PINSTYLE_CLK}, {id_CLKB, PINSTYLE_CLK}, {id_CEA, PINSTYLE_CE},
{id_CEB, PINSTYLE_CE}, {id_CSA0, PINSTYLE_PU}, {id_CSA1, PINSTYLE_PU},