[reggen] Correct hro to hwo for hwext registers readable by software
This commit changes reggen to 1) output a warning for hwext registers
that are readable for software but ready-only for hardware (hro) and to
2) change those registers to read/write for hardware (hrw). Otherwise,
software only ever reads back 0 and is not able to read the actual
register content.
This resolves lowRISC/OpenTitan#1428.
Signed-off-by: Pirmin Vogel <vogelpi@lowrisc.org>
diff --git a/util/reggen/validate.py b/util/reggen/validate.py
index 8986d15..a4f2873 100644
--- a/util/reggen/validate.py
+++ b/util/reggen/validate.py
@@ -797,6 +797,13 @@
if ierr:
error += 1
reg['hwext'] = "false"
+ elif hwext == True and default_hw == "hro" and (default_sw != "wo" and
+ default_sw != "r0w1c"):
+ log.warning(
+ rname +
+ ": hwext register readable by software cannot be hro. " +
+ "Changing it to hrw.")
+ default_hw = "hrw"
else:
reg['hwext'] = "false"
