[sysrst_ctrl] improve interrupt synchronization scheme
This follows a similar solution introduced for adc_ctrl here: #11904
to make sure that subsequent interrupt requests that occur with the
main bus clock gated do not get lost.
Signed-off-by: Michael Schaffner <msf@opentitan.org>
diff --git a/hw/ip/sysrst_ctrl/rtl/sysrst_ctrl.sv b/hw/ip/sysrst_ctrl/rtl/sysrst_ctrl.sv
index db07e96..15cdba7 100644
--- a/hw/ip/sysrst_ctrl/rtl/sysrst_ctrl.sv
+++ b/hw/ip/sysrst_ctrl/rtl/sysrst_ctrl.sv
@@ -332,20 +332,33 @@
assign hw2reg.wkup_status.d = 1'b1;
assign wkup_req_o = reg2hw.wkup_status.q;
- // Detect a rising edge so that the interrupt can be cleared
- // independently of the wakeup request.
+ logic aon_intr_req, aon_intr_ack;
+ always_ff @(posedge clk_aon_i or negedge rst_aon_ni) begin : p_intr_req_hold_reg
+ if(~rst_aon_ni) begin
+ aon_intr_req <= 1'b0;
+ end else begin
+ if (aon_intr_ack) begin
+ aon_intr_req <= 1'b0;
+ end else begin
+ aon_intr_req <= aon_intr_req || aon_intr_event_pulse;
+ end
+ end
+ end
+
+ // This synchronizes over a pulse if there is a pending request.
+ // If the main bus clock is not active, this will stall the synchronization until
+ // the clock becomes live again so that no interrupt requests are missed.
logic intr_event_pulse;
- prim_edge_detector #(
- .Width(1),
- .ResetValue('0),
- .EnSync(1)
- ) u_prim_edge_detector (
- .clk_i,
- .rst_ni,
- .d_i (aon_intr_event_pulse),
- .q_sync_o ( ),
- .q_posedge_pulse_o(intr_event_pulse),
- .q_negedge_pulse_o( )
+ prim_sync_reqack u_prim_sync_reqack (
+ .clk_src_i(clk_aon_i),
+ .rst_src_ni(rst_aon_ni),
+ .clk_dst_i(clk_i),
+ .rst_dst_ni(rst_ni),
+ .req_chk_i(1'b1),
+ .src_req_i(aon_intr_req),
+ .src_ack_o(aon_intr_ack),
+ .dst_req_o(intr_event_pulse),
+ .dst_ack_i(intr_event_pulse)
);
// Instantiate the interrupt module
diff --git a/hw/ip/sysrst_ctrl/sysrst_ctrl.core b/hw/ip/sysrst_ctrl/sysrst_ctrl.core
index e983509..a4bd29d 100644
--- a/hw/ip/sysrst_ctrl/sysrst_ctrl.core
+++ b/hw/ip/sysrst_ctrl/sysrst_ctrl.core
@@ -9,7 +9,6 @@
depend:
- lowrisc:constants:top_pkg
- lowrisc:prim:all
- - lowrisc:prim:edge_detector
- lowrisc:ip:tlul
files:
- rtl/sysrst_ctrl_reg_pkg.sv
