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Gowin. Add the ability to place registers in IOB
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IO blocks have registers: for input, for output and for OutputEnable
signal - IREG, OREG and TREG respectively.

Each of the registers has one implicit non-switched wire, which one
depends on the type of register (IREG has a Q wire, OREG has a D wire).
Although the registers can be activated independently of each other they
share the CLK, ClockEnable and LocalSetReset wires and this places
restrictions on the possible combinations of register types in a single
IO.

Register placement in IO blocks is enabled by specifying the command
line keys --vopt ireg_in_iob, --vopt oreg_in_iob, or --vopt ioreg_in_iob.

It should be noted that specifying these keys leads to attempts to place
registers in IO blocks, but no errors are generated in case of failure.

Signed-off-by: YRabbit <[email protected]>
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@yrabbit
yrabbit committed Dec 8, 2024
1 parent d810aac commit b82cf51
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Showing 4 changed files with 300 additions and 7 deletions.
19 changes: 19 additions & 0 deletions himbaechel/uarch/gowin/constids.inc
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Original file line number Diff line number Diff line change
Expand Up @@ -1312,3 +1312,22 @@ X(LSREN)

// EMCU
X(EMCU)

// Register placement options
X(IREG_IN_IOB)
X(OREG_IN_IOB)
X(IOREG_IN_IOB)
X(HAS_REG)
X(IREG_TYPE)
X(OREG_TYPE)
X(TREG_TYPE)
X(IREG_CLK_NET)
X(IREG_CE_NET)
X(IREG_LSR_NET)
X(OREG_CLK_NET)
X(OREG_CE_NET)
X(OREG_LSR_NET)
X(TREG_CLK_NET)
X(TREG_CE_NET)
X(TREG_LSR_NET)

11 changes: 11 additions & 0 deletions himbaechel/uarch/gowin/gowin.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -196,6 +196,17 @@ void GowinImpl::init(Context *ctx)
if (args.options.count("cst")) {
ctx->settings[ctx->id("cst.filename")] = args.options.at("cst");
}

// place registers in IO blocks
if (args.options.count("ireg_in_iob")) {
ctx->settings[id_IREG_IN_IOB] = Property(1);
}
if (args.options.count("oreg_in_iob")) {
ctx->settings[id_OREG_IN_IOB] = Property(1);
}
if (args.options.count("ioreg_in_iob")) {
ctx->settings[id_IOREG_IN_IOB] = Property(1);
}
}

// We do not allow the use of global wires that bypass a special router.
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4 changes: 4 additions & 0 deletions himbaechel/uarch/gowin/gowin.h
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Original file line number Diff line number Diff line change
Expand Up @@ -21,6 +21,10 @@ inline bool is_dff(const CellInfo *cell) { return type_is_dff(cell->type); }
inline bool type_is_alu(IdString cell_type) { return cell_type == id_ALU; }
inline bool is_alu(const CellInfo *cell) { return type_is_alu(cell->type); }

// io
inline bool type_is_io(IdString cell_type) { return cell_type.in(id_IBUF, id_OBUF, id_IOBUF, id_TBUF); }
inline bool is_io(const CellInfo *cell) { return type_is_io(cell->type); }

inline bool type_is_diffio(IdString cell_type)
{
return cell_type.in(id_ELVDS_IOBUF, id_ELVDS_IBUF, id_ELVDS_TBUF, id_ELVDS_OBUF, id_TLVDS_IOBUF, id_TLVDS_IBUF,
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273 changes: 266 additions & 7 deletions himbaechel/uarch/gowin/pack.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -184,8 +184,9 @@ struct GowinPacker

for (auto &cell : ctx->cells) {
CellInfo &ci = *cell.second;
if (!ci.type.in(id_IBUF, id_OBUF, id_TBUF, id_IOBUF))
if (!is_io(&ci)) {
continue;
}
if (ci.attrs.count(id_BEL) == 0) {
log_error("Unconstrained IO:%s\n", ctx->nameOf(&ci));
}
Expand All @@ -204,10 +205,7 @@ struct GowinPacker
// ===================================
// Differential IO
// ===================================
static bool is_iob(const Context *ctx, CellInfo *cell)
{
return (cell->type.in(id_IBUF, id_OBUF, id_TBUF, id_IOBUF));
}
static bool is_iob(const Context *ctx, CellInfo *cell) { return is_io(cell); }

std::pair<CellInfo *, CellInfo *> get_pn_cells(const CellInfo &ci)
{
Expand Down Expand Up @@ -502,7 +500,9 @@ struct GowinPacker
out_iob->disconnectPort(id_I);
ci.disconnectPort(out_port);
if (ci.type == id_IOLOGICO_EMPTY) {
ci.movePortTo(id_D, out_iob, id_I);
if (ci.attrs.count(id_HAS_REG) == 0) {
ci.movePortTo(id_D, out_iob, id_I);
}
return;
}
set_daaj_nets(ci, iob_bel);
Expand Down Expand Up @@ -630,7 +630,9 @@ struct GowinPacker
in_iob->disconnectPort(id_O);
ci.disconnectPort(in_port);
if (ci.type == id_IOLOGICI_EMPTY) {
ci.movePortTo(id_Q, in_iob, id_O);
if (ci.attrs.count(id_HAS_REG) == 0) {
ci.movePortTo(id_Q, in_iob, id_O);
}
return;
}

Expand All @@ -640,6 +642,260 @@ struct GowinPacker
make_iob_nets(*in_iob);
}

static bool is_ff(const Context *ctx, CellInfo *cell) { return is_dff(cell); }

static bool incompatible_ffs(IdString type_a, IdString type_b)
{
return type_a != type_b &&
((type_a == id_DFFS && type_b != id_DFFR) || (type_a == id_DFFR && type_b != id_DFFS) ||
(type_a == id_DFFSE && type_b != id_DFFRE) || (type_a == id_DFFRE && type_b != id_DFFSE) ||
(type_a == id_DFFP && type_b != id_DFFC) || (type_a == id_DFFC && type_b != id_DFFP) ||
(type_a == id_DFFPE && type_b != id_DFFCE) || (type_a == id_DFFCE && type_b != id_DFFPE) ||
(type_a == id_DFFNS && type_b != id_DFFNR) || (type_a == id_DFFNR && type_b != id_DFFNS) ||
(type_a == id_DFFNSE && type_b != id_DFFNRE) || (type_a == id_DFFNRE && type_b != id_DFFNSE) ||
(type_a == id_DFFNP && type_b != id_DFFNC) || (type_a == id_DFFNC && type_b != id_DFFNP) ||
(type_a == id_DFFNPE && type_b != id_DFFNCE) || (type_a == id_DFFNCE && type_b != id_DFFNPE));
}

void pack_io_regs()
{
log_info("Pack FFs into IO cells...\n");
std::vector<IdString> cells_to_remove;
std::vector<IdString> nets_to_remove;
std::vector<std::unique_ptr<CellInfo>> new_cells;

for (auto &cell : ctx->cells) {
CellInfo &ci = *cell.second;
if (!is_io(&ci)) {
continue;
}

// In the case of placing multiple registers in the IO it should be
// noted that the CLK, ClockEnable and LocalSetReset nets must
// match.
const NetInfo *clk_net = nullptr;
const NetInfo *ce_net = nullptr;
const NetInfo *lsr_net = nullptr;
IdString reg_type;

// input reg in IO
CellInfo *iologic_i = nullptr;
if ((ci.type == id_IBUF && ctx->settings.count(id_IREG_IN_IOB)) ||
(ci.type == id_IOBUF && ctx->settings.count(id_IOREG_IN_IOB))) {
// OBUF O -> D FF
CellInfo *ff = net_only_drives(ctx, ci.ports.at(id_O).net, is_ff, id_D, true);
if (ff != nullptr) {
BelId l_bel = get_iologico_bel(&ci);
if (l_bel == BelId()) {
continue;
}
if (ctx->debug) {
log_info(" trying %s ff as Input Register of %s IO\n", ctx->nameOf(ff), ctx->nameOf(&ci));
}

clk_net = ff->getPort(id_CLK);
ce_net = ff->getPort(id_CE);
for (IdString port : {id_SET, id_RESET, id_PRESET, id_CLEAR}) {
lsr_net = ff->getPort(port);
if (lsr_net != nullptr) {
break;
}
}
reg_type = ff->type;

// create IOLOGIC cell for flipflop
IdString iologic_name = gwu.create_aux_name(ci.name, 0, "_iobff$");
auto iologic_cell = gwu.create_cell(iologic_name, id_IOLOGICI_EMPTY);
new_cells.push_back(std::move(iologic_cell));
iologic_i = new_cells.back().get();

// move ports
for (auto &port : ff->ports) {
IdString port_name = port.first;
ff->movePortTo(port_name, iologic_i, port_name != id_Q ? port_name : id_Q4);
}
if (ctx->verbose) {
log_info(" place FF %s into IBUF %s, make iologic_i %s\n", ctx->nameOf(ff), ctx->nameOf(&ci),
ctx->nameOf(iologic_i));
}
iologic_i->setAttr(id_HAS_REG, 1);
iologic_i->setAttr(id_IREG_TYPE, ff->type.str(ctx));
cells_to_remove.push_back(ff->name);
}
}

// output reg in IO
CellInfo *iologic_o = nullptr;
if ((ci.type == id_OBUF && ctx->settings.count(id_OREG_IN_IOB)) ||
(ci.type == id_IOBUF && ctx->settings.count(id_IOREG_IN_IOB))) {
while (1) {
// OBUF I <- Q FF
if (ci.ports.at(id_I).net->users.entries() != 1) {
break;
}
CellInfo *ff = net_driven_by(ctx, ci.ports.at(id_I).net, is_ff, id_Q);
if (ff != nullptr) {
BelId l_bel = get_iologico_bel(&ci);
if (l_bel == BelId()) {
break;
}
if (ctx->debug) {
log_info(" trying %s ff as Output Register of %s IO\n", ctx->nameOf(ff), ctx->nameOf(&ci));
}

const NetInfo *this_clk_net = ff->getPort(id_CLK);
const NetInfo *this_ce_net = ff->getPort(id_CE);
const NetInfo *this_lsr_net;
for (IdString port : {id_SET, id_RESET, id_PRESET, id_CLEAR}) {
this_lsr_net = ff->getPort(port);
if (this_lsr_net != nullptr) {
break;
}
}
// The IOBUF may already have registers placed
if (ci.type == id_IOBUF) {
if (iologic_i != nullptr) {
if (incompatible_ffs(ff->type, reg_type)) {
if (ctx->debug) {
log_info(" FF types conflict:%s vs %s\n", ff->type.c_str(ctx),
reg_type.c_str(ctx));
}
break;
} else {
if (clk_net != this_clk_net || ce_net != this_ce_net || lsr_net != this_lsr_net) {
if (ctx->debug) {
log_info(" Nets conflict.\n");
}
break;
}
}
} else {
clk_net = this_clk_net;
ce_net = this_ce_net;
lsr_net = this_lsr_net;
reg_type = ff->type;
}
}

// create IOLOGIC cell for flipflop
IdString iologic_name = gwu.create_aux_name(ci.name, 1, "_iobff$");
auto iologic_cell = gwu.create_cell(iologic_name, id_IOLOGICO_EMPTY);
new_cells.push_back(std::move(iologic_cell));
iologic_o = new_cells.back().get();

// move ports
for (auto &port : ff->ports) {
IdString port_name = port.first;
ff->movePortTo(port_name, iologic_o, port_name != id_D ? port_name : id_D0);
}
if (ctx->verbose) {
log_info(" place FF %s into OBUF %s, make iologic_o %s\n", ctx->nameOf(ff),
ctx->nameOf(&ci), ctx->nameOf(iologic_o));
}
iologic_o->setAttr(id_HAS_REG, 1);
iologic_o->setAttr(id_OREG_TYPE, ff->type.str(ctx));
cells_to_remove.push_back(ff->name);
}
break;
}
}

// output enable reg in IO
if (ci.type == id_IOBUF && ctx->settings.count(id_IOREG_IN_IOB)) {
while (1) {
// IOBUF OEN <- Q FF
if (ci.ports.at(id_OEN).net->users.entries() != 1) {
continue;
}
CellInfo *ff = net_driven_by(ctx, ci.ports.at(id_OEN).net, is_ff, id_Q);
if (ff != nullptr) {
BelId l_bel = get_iologico_bel(&ci);
if (l_bel == BelId()) {
continue;
}
if (ctx->debug) {
log_info(" trying %s ff as Output Enable Register of %s IO\n", ctx->nameOf(ff),
ctx->nameOf(&ci));
}

const NetInfo *this_clk_net = ff->getPort(id_CLK);
const NetInfo *this_ce_net = ff->getPort(id_CE);
const NetInfo *this_lsr_net;
for (IdString port : {id_SET, id_RESET, id_PRESET, id_CLEAR}) {
this_lsr_net = ff->getPort(port);
if (this_lsr_net != nullptr) {
break;
}
}

// The IOBUF may already have registers placed
if (iologic_i != nullptr || iologic_o != nullptr) {
if (iologic_o == nullptr) {
iologic_o = iologic_i;
}
if (incompatible_ffs(ff->type, reg_type)) {
if (ctx->debug) {
log_info(" FF types conflict:%s vs %s\n", ff->type.c_str(ctx),
reg_type.c_str(ctx));
}
break;
} else {
if (clk_net != this_clk_net || ce_net != this_ce_net || lsr_net != this_lsr_net) {
if (ctx->debug) {
log_info(" Nets conflict.\n");
}
break;
}
}
}

if (iologic_o == nullptr) {
// create IOLOGIC cell for flipflop
IdString iologic_name = gwu.create_aux_name(ci.name, 2, "_iobff$");
auto iologic_cell = gwu.create_cell(iologic_name, id_IOLOGICO_EMPTY);
new_cells.push_back(std::move(iologic_cell));
iologic_o = new_cells.back().get();
}

// move ports
for (auto &port : ff->ports) {
IdString port_name = port.first;
if (port_name == id_Q) {
continue;
}
ff->movePortTo(port_name, iologic_o, port_name != id_D ? port_name : id_TX);
}

nets_to_remove.push_back(ci.getPort(id_OEN)->name);
ci.disconnectPort(id_OEN);
ff->disconnectPort(id_Q);

if (ctx->verbose) {
log_info(" place FF %s into IOBUF %s, make iologic_o %s\n", ctx->nameOf(ff),
ctx->nameOf(&ci), ctx->nameOf(iologic_o));
}
iologic_o->setAttr(id_HAS_REG, 1);
iologic_o->setAttr(id_TREG_TYPE, ff->type.str(ctx));
cells_to_remove.push_back(ff->name);
}
break;
}
}
}

for (auto cell : cells_to_remove) {
ctx->cells.erase(cell);
}

for (auto &ncell : new_cells) {
ctx->cells[ncell->name] = std::move(ncell);
}

for (auto net : nets_to_remove) {
ctx->nets.erase(net);
}
}

void pack_iodelay()
{
log_info("Pack IODELAY...\n");
Expand Down Expand Up @@ -3587,6 +3843,9 @@ struct GowinPacker
pack_diff_iobs();
ctx->check();

pack_io_regs();
ctx->check();

pack_iodelay();
ctx->check();

Expand Down

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