[kmac] Add a condition to move to Idle directly
This commit addresses the issue #6408
kmac_app FSM asserts CmdDone right at the same cycle it receives
absorbed signal. The main FSM in kmac.sv assumes absorbed and done
signals are separated.
This commit adds one condition in KmacWait state. If both signals are
high, then the FSM skips Digest state and moves to the Idle state
directly.
Signed-off-by: Eunchan Kim <eunchan@opentitan.org>
diff --git a/hw/ip/kmac/rtl/kmac.sv b/hw/ip/kmac/rtl/kmac.sv
index 038b2f7..3de1942 100644
--- a/hw/ip/kmac/rtl/kmac.sv
+++ b/hw/ip/kmac/rtl/kmac.sv
@@ -519,7 +519,12 @@
KmacMsgFeed: begin
entropy_in_progress = 1'b 1;
// If absorbed, move to Digest
- if (sha3_absorbed) begin
+ if (sha3_absorbed && sha3_done) begin
+ // absorbed and done can be asserted at a cycle if Applications have
+ // requested the hash operation. kmac_app FSM issues CmdDone command
+ // if it receives absorbed signal.
+ kmac_st_d = KmacIdle;
+ end else if (sha3_absorbed && !sha3_done) begin
kmac_st_d = KmacDigest;
end else begin
kmac_st_d = KmacMsgFeed;
