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Cut through-path on reset halt request from debug module to bus

This commit is contained in:
Luke Wren 2023-01-19 13:46:55 +00:00
parent 7fbdb69328
commit 7101cccf3b
1 changed files with 18 additions and 8 deletions
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18
hdl/hazard3_csr.v
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@ -1126,6 +1126,7 @@ reg have_just_reset;
reg step_halt_req;
reg dbg_req_resume_prev;
reg dbg_req_halt_prev;
reg dbg_req_halt_on_reset_sticky;
reg pending_dbg_resume_prev;
wire pending_dbg_resume = (pending_dbg_resume_prev || dbg_req_resume_prev) && debug_mode;
@ -1145,13 +1146,21 @@ end
always @ (posedge clk or negedge rst_n) begin
if (!rst_n) begin
have_just_reset <= |DEBUG_SUPPORT;
dbg_req_halt_on_reset_sticky <= 1'b0;
step_halt_req <= 1'b0;
dbg_req_resume_prev <= 1'b0;
pending_dbg_resume_prev <= 1'b0;
end else if (DEBUG_SUPPORT) begin
if (instr_ret)
have_just_reset <= 1'b0;
// One-cycle delay on assertion of reset halt req is harmless because
// of a matching delay on the first instruction fetch (reset_holdoff).
if (have_just_reset && dbg_req_halt_on_reset) begin
dbg_req_halt_on_reset_sticky <= 1'b1;
end else if (enter_debug_mode) begin
dbg_req_halt_on_reset_sticky <= 1'b0;
end
dbg_req_resume_prev <= dbg_req_resume;
if (debug_mode) begin
@ -1202,7 +1211,7 @@ wire want_halt_except = DEBUG_SUPPORT && !debug_mode && (
// access. Others are fine because they are never mid-instruction in stage 2.
wire want_halt_irq_if_no_exception = DEBUG_SUPPORT && !debug_mode && !want_halt_except && (
(dbg_req_halt_prev && !delay_irq_entry) ||
(dbg_req_halt_on_reset && have_just_reset) ||
dbg_req_halt_on_reset_sticky ||
step_halt_req
);
@ -1215,7 +1224,7 @@ wire want_halt_irq = want_halt_irq_if_no_exception && !halt_delayed_by_exception
assign dcause_next =
except == EXCEPT_EBREAK && except_to_d_mode ? 3'h2 : // trigger (priority 4)
except == EXCEPT_EBREAK ? 3'h1 : // ebreak (priority 3)
dbg_req_halt_prev || (dbg_req_halt_on_reset && have_just_reset) ? 3'h3 : // halt or reset-halt (priority 1, 2)
dbg_req_halt_prev || dbg_req_halt_on_reset ? 3'h3 : // halt or reset-halt (priority 1, 2)
3'h4; // single-step (priority 0)
assign trap_is_debug_entry = |DEBUG_SUPPORT && !debug_mode && (want_halt_irq || want_halt_except);
@ -1229,7 +1238,8 @@ assign dbg_instr_caught_ebreak = debug_mode && except == EXCEPT_EBREAK && trap_e
// Note we exclude ebreak from here regardless of dcsr.ebreakm, since we are
// already in debug mode at this point
assign dbg_instr_caught_exception = debug_mode && except != EXCEPT_NONE && except != EXCEPT_EBREAK && trap_enter_rdy;
assign dbg_instr_caught_exception = debug_mode && except != EXCEPT_NONE &&
except != EXCEPT_EBREAK && trap_enter_rdy;
// ----------------------------------------------------------------------------
// Trap request generation