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Controller: Fix exception cause ID of fast interrupts

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This commit fixes the generation of the exception cause ID for fast
interrupts. Without this commit, the core tries to handle fast
interrupts using the handlers of other interrupts like external,
software, and timer interrupts.

This commit resolves lowRISC/ibex#290 reported by @udinator.
This commit is contained in:
Pirmin Vogel 2019-09-09 11:00:07 +01:00
parent b87ed7c82e
commit 8d3d87ae53
1 changed files with 22 additions and 18 deletions
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40
rtl/ibex_controller.sv
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@ -113,7 +113,7 @@ module ibex_controller (
logic enter_debug_mode;
logic handle_irq;
logic [4:0] mfip_id;
logic [3:0] mfip_id;
logic unused_csr_mtip;
`ifndef SYNTHESIS
@ -164,22 +164,22 @@ module ibex_controller (
// generate ID of fast interrupts, highest priority to highest ID
always_comb begin : gen_mfip_id
if (csr_mfip_i[14]) mfip_id = 5'd14;
else if (csr_mfip_i[13]) mfip_id = 5'd13;
else if (csr_mfip_i[12]) mfip_id = 5'd12;
else if (csr_mfip_i[11]) mfip_id = 5'd11;
else if (csr_mfip_i[10]) mfip_id = 5'd10;
else if (csr_mfip_i[ 9]) mfip_id = 5'd9;
else if (csr_mfip_i[ 8]) mfip_id = 5'd8;
else if (csr_mfip_i[ 7]) mfip_id = 5'd7;
else if (csr_mfip_i[ 6]) mfip_id = 5'd6;
else if (csr_mfip_i[ 5]) mfip_id = 5'd5;
else if (csr_mfip_i[ 5]) mfip_id = 5'd5;
else if (csr_mfip_i[ 4]) mfip_id = 5'd4;
else if (csr_mfip_i[ 3]) mfip_id = 5'd3;
else if (csr_mfip_i[ 2]) mfip_id = 5'd2;
else if (csr_mfip_i[ 1]) mfip_id = 5'd1;
else mfip_id = 5'd0;
if (csr_mfip_i[14]) mfip_id = 4'd14;
else if (csr_mfip_i[13]) mfip_id = 4'd13;
else if (csr_mfip_i[12]) mfip_id = 4'd12;
else if (csr_mfip_i[11]) mfip_id = 4'd11;
else if (csr_mfip_i[10]) mfip_id = 4'd10;
else if (csr_mfip_i[ 9]) mfip_id = 4'd9;
else if (csr_mfip_i[ 8]) mfip_id = 4'd8;
else if (csr_mfip_i[ 7]) mfip_id = 4'd7;
else if (csr_mfip_i[ 6]) mfip_id = 4'd6;
else if (csr_mfip_i[ 5]) mfip_id = 4'd5;
else if (csr_mfip_i[ 5]) mfip_id = 4'd5;
else if (csr_mfip_i[ 4]) mfip_id = 4'd4;
else if (csr_mfip_i[ 3]) mfip_id = 4'd3;
else if (csr_mfip_i[ 2]) mfip_id = 4'd2;
else if (csr_mfip_i[ 1]) mfip_id = 4'd1;
else mfip_id = 4'd0;
end
assign unused_csr_mtip = csr_mtip_i;
@ -360,7 +360,11 @@ module ibex_controller (
exc_cause_o = EXC_CAUSE_IRQ_NM;
nmi_mode_d = 1'b1; // enter NMI mode
end else if (csr_mfip_i != 15'b0) begin
exc_cause_o = exc_cause_e'({1'b1, mfip_id});
// generate exception cause ID from fast interrupt ID:
// - first bit distinguishes interrupts from exceptions,
// - second bit adds 16 to fast interrupt ID
// for example EXC_CAUSE_IRQ_FAST_0 = {1'b1, 5'd16}
exc_cause_o = exc_cause_e'({2'b11, mfip_id});
end else if (csr_meip_i) begin
exc_cause_o = EXC_CAUSE_IRQ_EXTERNAL_M;
end else if (csr_msip_i) begin