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ice40: Rework pull-up attribute copy to SB_IO blocks

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We try to copy the attribute only when there is a chance for
the output driver to not be active.

Note that this can _also_ happen when a port is specified as
output but has a TBUF, which the previous code wasn't handling.

We could copy the attribute "all-the-time" but this would
mean if a user specified a `-pullup yes` in the PCF for a
permanently driven output pin, we'd be burning power for
nothing.

Signed-off-by: Sylvain Munaut <tnt@246tNt.com>
This commit is contained in:
Sylvain Munaut 2023-01-29 21:11:54 +01:00
parent f80b871dd5
commit 0cf5006e3b
1 changed files with 14 additions and 8 deletions
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22
ice40/cells.cc
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@ -404,25 +404,23 @@ void dff_to_lc(const Context *ctx, CellInfo *dff, CellInfo *lc, bool pass_thru_l
void nxio_to_sb(Context *ctx, CellInfo *nxio, CellInfo *sbio, pool<IdString> &todelete_cells)
{
bool pull_up_attr = false;
if (nxio->type == ctx->id("$nextpnr_ibuf")) {
sbio->params[id_PIN_TYPE] = 1;
auto pu_attr = nxio->attrs.find(id_PULLUP);
if (pu_attr != nxio->attrs.end())
sbio->params[id_PULLUP] = pu_attr->second;
nxio->movePortTo(id_O, sbio, id_D_IN_0);
pull_up_attr = true;
} else if (nxio->type == ctx->id("$nextpnr_obuf")) {
sbio->params[id_PIN_TYPE] = 25;
nxio->movePortTo(id_I, sbio, id_D_OUT_0);
} else if (nxio->type == ctx->id("$nextpnr_iobuf")) {
// N.B. tristate will be dealt with below
NetInfo *i = nxio->getPort(id_I);
if (i == nullptr || i->driver.cell == nullptr)
if (i == nullptr || i->driver.cell == nullptr) {
sbio->params[id_PIN_TYPE] = 1;
else
pull_up_attr = true;
} else
sbio->params[id_PIN_TYPE] = 25;
auto pu_attr = nxio->attrs.find(id_PULLUP);
if (pu_attr != nxio->attrs.end())
sbio->params[id_PULLUP] = pu_attr->second;
nxio->movePortTo(id_I, sbio, id_D_OUT_0);
nxio->movePortTo(id_O, sbio, id_D_IN_0);
} else {
@ -465,6 +463,7 @@ void nxio_to_sb(Context *ctx, CellInfo *nxio, CellInfo *sbio, pool<IdString> &to
sbio->params[id_PIN_TYPE] = 41;
tbuf->movePortTo(id_A, sbio, id_D_OUT_0);
tbuf->movePortTo(id_E, sbio, id_OUTPUT_ENABLE);
pull_up_attr = true;
if (donet->users.entries() > 1) {
for (auto user : donet->users)
@ -476,6 +475,13 @@ void nxio_to_sb(Context *ctx, CellInfo *nxio, CellInfo *sbio, pool<IdString> &to
ctx->nets.erase(donet->name);
todelete_cells.insert(tbuf->name);
}
// Copy pull-up attribute if there's any chance output driver isn't active
if (pull_up_attr) {
auto pu_attr = nxio->attrs.find(id_PULLUP);
if (pu_attr != nxio->attrs.end())
sbio->params[id_PULLUP] = pu_attr->second;
}
}
uint8_t sb_pll40_type(const BaseCtx *ctx, const CellInfo *cell)