How to get value of 'Param' of the WHERE clause in the FDW?

Please help.... I'm doing a following query to a foreign wrapper:
   FUNCTION fwcall(text) ....   SELECT * FROM fwtable WHERE col=$1....  ;

   ...

   SELECT * from fdwcall('abc123');

I'm looking for a way to get that parameter 'abc123' value in the FDW wrapper code...

It seems like during fdwPlan(..., RelOptInfo *baserel) stage I'm getting  baserel->baserestrictinfo, in which I see a Node *x  of  IsA(x, Param).  But it looks like the value 'abc123' is not yet available in the planning stage, right?   And I don't see how can I get baserestrictinfo in the execution stage or if the 'abc123' value would be there...

Can somebody kick me to the right direction?  Please?

Thanks,