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UberDDR3
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use a 4-bit counter plus a 4-bit mask for tracking delay in every bank 

this is the optimized delay-tracking mechanism on which the 32-bit shift regs is replaced by a 4-bit counter plus a 4-bit mask. This uses lower resources but still able to track the delays and the exact slot number where the delay is already satisfied (hence no added latency)
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Angelo Jacobo 2023-03-30 18:17:46 +08:00 committed by GitHub
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112
rtl/ddr3_controller.v
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@ -89,8 +89,8 @@ module ddr3_controller #(
localparam READ_SLOT = get_slot(CMD_RD),
WRITE_SLOT = get_slot(CMD_WR),
ACTIVATE_SLOT = get_slot(CMD_ACT),
PRECHARGE_SLOT = get_slot(CMD_PRE);
ANTICIPATE_ACTIVATE_SLOT = get_slot(CMD_ACT),
ANTICIPATE_PRECHARGE_SLOT = get_slot(CMD_PRE);
///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
@ -503,7 +503,6 @@ module ddr3_controller #(
// 1s are preserved and the thread will remain all 1s until it is
// overwritten
(*keep*) reg[1:0] f_stage;
always @* begin
request_pending_d = request_pending_q;
o_wb_ack_d = 0;
@ -544,7 +543,6 @@ module ddr3_controller #(
o_wb_stall_d = 0;
request_pending_d = 0;
o_wb_ack_d = 1;
delay_before_precharge_added_delay = {{8{1'b1}}, added_delay(WRITE_SLOT), {{((CWL_nCK + 3'd4 + ns_to_nCK(tWR)) % 3'd4)}{1'b0}}};
delay_before_precharge_mask_d[request_bank] = delay_before_precharge_added_delay[3:0]? delay_before_precharge_added_delay[3:0]:delay_before_precharge_added_delay[7:4];
delay_before_precharge_counter_d[request_bank] = delay_before_precharge_added_delay[3:0]? ($floor((CWL_nCK + 4 + ns_to_nCK(tWR))/4) - 1): ($floor((CWL_nCK + 4 + ns_to_nCK(tWR))/4) - 1 + 1);
@ -563,7 +561,6 @@ module ddr3_controller #(
else begin
cmd_d[WRITE_SLOT] = {1'b0, CMD_WR[2:0], {{ROW_BITS+BA_BITS-4'd12}{1'b0}} , request_col[10] , 1'b0 , request_col[9:0]};
end
f_stage = 3;
end
//read request
@ -571,7 +568,6 @@ module ddr3_controller #(
o_wb_stall_d = 0;
request_pending_d = 0;
o_wb_ack_d = 1;
delay_before_precharge_added_delay = {{8{1'b1}}, added_delay(READ_SLOT), {{ns_to_nCK(tRTP) % 3'd4}{1'b0}}};
delay_before_precharge_mask_d[request_bank] = delay_before_precharge_added_delay[3:0]? delay_before_precharge_added_delay[3:0]:delay_before_precharge_added_delay[7:4];
delay_before_precharge_counter_d[request_bank] = delay_before_precharge_added_delay[3:0]? ($floor(ns_to_nCK(tRTP)/4) - 1): ($floor(ns_to_nCK(tRTP)/4) - 1 + 1);
@ -590,12 +586,11 @@ module ddr3_controller #(
else begin
cmd_d[READ_SLOT] = {1'b0, CMD_RD[2:0], {{ROW_BITS+BA_BITS-4'd12}{1'b0}} , request_col[10] , 1'b0 , request_col[9:0]};
end
f_stage = 3;
end
end
//bank is idle so activate it
else if(!bank_status_q[request_bank]) begin
else if(!bank_status_q[request_bank] && delay_before_activate_mask_q[request_bank][3:0] && delay_before_activate_counter_q[request_bank] == 0) begin
delay_before_read_added_delay = {{8{1'b1}}, delay_before_activate_mask_q[request_bank], {{ns_to_nCK(tRCD) % 3'd4}{1'b0}}};
delay_before_read_mask_d[request_bank] = delay_before_read_added_delay[3:0]? delay_before_read_added_delay[3:0]:delay_before_read_added_delay[7:4];
delay_before_read_counter_d[request_bank] = delay_before_read_added_delay[3:0]? ($floor(ns_to_nCK(tRCD) /4) - 1): ($floor(ns_to_nCK(tRCD) /4) - 1 + 1);
@ -603,80 +598,56 @@ module ddr3_controller #(
delay_before_write_added_delay = {{8{1'b1}}, delay_before_activate_mask_q[request_bank], {{ns_to_nCK(tRCD) % 3'd4}{1'b0}}};
delay_before_write_mask_d[request_bank] = delay_before_write_added_delay[3:0]? delay_before_write_added_delay[3:0]:delay_before_write_added_delay[7:4];
delay_before_write_counter_d[request_bank] = delay_before_write_added_delay[3:0]? ($floor(ns_to_nCK(tRCD)/4) - 1): ($floor(ns_to_nCK(tRCD)/4) - 1 + 1);
if(delay_before_activate_mask_q[request_bank][3:0] && delay_before_activate_counter_q[request_bank] == 0) begin
cmd_d[0] = {!delay_before_activate_mask_q[request_bank][0], CMD_ACT[2:0] , request_bank , request_row};
cmd_d[1] = {(delay_before_activate_mask_q[request_bank][1] ~^ delay_before_activate_mask_q[request_bank][0]), CMD_ACT[2:0] , request_bank , request_row};
cmd_d[2] = {(delay_before_activate_mask_q[request_bank][2] ~^ delay_before_activate_mask_q[request_bank][1]), CMD_ACT[2:0] , request_bank , request_row};
cmd_d[3] = {(delay_before_activate_mask_q[request_bank][3] ~^ delay_before_activate_mask_q[request_bank][2]), CMD_ACT[2:0] , request_bank , request_row}; //4 + 3 + 14 = 21
bank_status_d[request_bank] = 1'b1;
bank_active_row_d[request_bank] = request_row;
f_stage = 2;
end
cmd_d[0] = {!delay_before_activate_mask_q[request_bank][0], CMD_ACT[2:0] , request_bank , request_row};
cmd_d[1] = {(delay_before_activate_mask_q[request_bank][1] ~^ delay_before_activate_mask_q[request_bank][0]), CMD_ACT[2:0] , request_bank , request_row};
cmd_d[2] = {(delay_before_activate_mask_q[request_bank][2] ~^ delay_before_activate_mask_q[request_bank][1]), CMD_ACT[2:0] , request_bank , request_row};
cmd_d[3] = {(delay_before_activate_mask_q[request_bank][3] ~^ delay_before_activate_mask_q[request_bank][2]), CMD_ACT[2:0] , request_bank , request_row}; //4 + 3 + 14 = 21
bank_status_d[request_bank] = 1'b1;
bank_active_row_d[request_bank] = request_row;
end
//bank is not idle but wrong row is activated so do precharge
else begin
else if(bank_status_q[request_bank] && bank_active_row_q[request_bank] != request_row && delay_before_precharge_mask_q[request_bank][3:0] && delay_before_precharge_counter_q[request_bank] ==0) begin
delay_before_activate_added_delay = {{8{1'b1}}, delay_before_precharge_mask_q[request_bank], {{ns_to_nCK(tRP) % 3'd4}{1'b0}}};
delay_before_activate_mask_d[request_bank] = delay_before_activate_added_delay[3:0]? delay_before_activate_added_delay[3:0]:delay_before_activate_added_delay[7:4];
delay_before_activate_counter_d[request_bank] = delay_before_activate_added_delay[3:0]? ($floor(ns_to_nCK(tRP)/4) - 1): ($floor(ns_to_nCK(tRP)/4) - 1 + 1);
//delay_before_activate_d[request_bank][31:ns_to_nCK(tRP) - 4] = delay_before_precharge_q[request_bank]; //this will get overwritten at next cock cycle
if(delay_before_precharge_mask_q[request_bank][3:0] && delay_before_precharge_counter_q[request_bank] ==0) begin
cmd_d[0] = {!delay_before_precharge_mask_q[request_bank][0], CMD_PRE[2:0], request_bank, { {{ROW_BITS-4'd11}{1'b0}} , 1'b0 , request_row[9:0] } };
cmd_d[1] = {(delay_before_precharge_mask_q[request_bank][1] ~^ delay_before_precharge_mask_q[request_bank][0]), CMD_PRE[2:0], request_bank, { {{ROW_BITS-4'd11}{1'b0}} , 1'b0 , request_row[9:0] } };
cmd_d[2] = {(delay_before_precharge_mask_q[request_bank][2] ~^ delay_before_precharge_mask_q[request_bank][1]), CMD_PRE[2:0], request_bank, { {{ROW_BITS-4'd11}{1'b0}} , 1'b0 , request_row[9:0] } };
cmd_d[3] = {(delay_before_precharge_mask_q[request_bank][3] ~^ delay_before_precharge_mask_q[request_bank][2]), CMD_PRE[2:0], request_bank, { {{ROW_BITS-4'd11}{1'b0}} , 1'b0 , request_row[9:0] } };
bank_status_d[request_bank] = 1'b0;
f_stage = 1;
end
cmd_d[0] = {!delay_before_precharge_mask_q[request_bank][0], CMD_PRE[2:0], request_bank, { {{ROW_BITS-4'd11}{1'b0}} , 1'b0 , request_row[9:0] } };
cmd_d[1] = {(delay_before_precharge_mask_q[request_bank][1] ~^ delay_before_precharge_mask_q[request_bank][0]), CMD_PRE[2:0], request_bank, { {{ROW_BITS-4'd11}{1'b0}} , 1'b0 , request_row[9:0] } };
cmd_d[2] = {(delay_before_precharge_mask_q[request_bank][2] ~^ delay_before_precharge_mask_q[request_bank][1]), CMD_PRE[2:0], request_bank, { {{ROW_BITS-4'd11}{1'b0}} , 1'b0 , request_row[9:0] } };
cmd_d[3] = {(delay_before_precharge_mask_q[request_bank][3] ~^ delay_before_precharge_mask_q[request_bank][2]), CMD_PRE[2:0], request_bank, { {{ROW_BITS-4'd11}{1'b0}} , 1'b0 , request_row[9:0] } };
bank_status_d[request_bank] = 1'b0;
end
/*
//anticipated activate and precharge commands will only be allowed during the read/write cycles
if(bank_status[request_bank] && bank_active_row[request_bank] == request_row) begin
if(bank_status_q[request_bank] && bank_active_row_q[request_bank] == request_row) begin
//anticipated bank is not idle but wrong row is currently activated so do precharge
if(bank_status[next_bank] && bank_active_row[next_bank] != next_row) begin
if(bank_status_q[next_bank] && bank_active_row_q[next_bank] != next_row && delay_before_precharge_mask_q[next_bank][ANTICIPATE_PRECHARGE_SLOT] && delay_before_precharge_counter_q[next_bank] ==0) begin
delay_before_activate_added_delay = {{8{1'b1}}, delay_before_precharge_mask_q[next_bank], {{ns_to_nCK(tRP) % 3'd4}{1'b0}}};
delay_before_activate_mask_d[next_bank] = delay_before_activate_added_delay[3:0]? delay_before_activate_added_delay[3:0]:delay_before_activate_added_delay[7:4];
delay_before_activate_counter_d[next_bank] = delay_before_activate_added_delay[3:0]? ($floor(ns_to_nCK(tRP)/4) - 1): ($floor(ns_to_nCK(tRP)/4) - 1 + 1);
if(delay_before_precharge_mask_q[next_bank][3:0] && delay_before_precharge_counter_q[next_bank] ==0) begin
cmd_d[0] = {!delay_before_precharge_mask_q[next_bank][0], CMD_PRE[2:0], next_bank, { {{ROW_BITS-4'd11}{1'b0}} , 1'b0 , request_row[9:0] } };
cmd_d[1] = {(delay_before_precharge_mask_q[next_bank][1] ~^ delay_before_precharge_mask_q[next_bank][0]), CMD_PRE[2:0], next_bank, { {{ROW_BITS-4'd11}{1'b0}} , 1'b0 , request_row[9:0] } };
cmd_d[2] = {(delay_before_precharge_mask_q[next_bank][2] ~^ delay_before_precharge_mask_q[next_bank][1]), CMD_PRE[2:0], next_bank, { {{ROW_BITS-4'd11}{1'b0}} , 1'b0 , request_row[9:0] } };
cmd_d[3] = {(delay_before_precharge_mask_q[next_bank][3] ~^ delay_before_precharge_mask_q[next_bank][2]), CMD_PRE[2:0], next_bank, { {{ROW_BITS-4'd11}{1'b0}} , 1'b0 , request_row[9:0] } };
bank_status_d[next_bank] = 1'b0;
f_stage = 1;
end
delay_before_activate_counter_d[next_bank] = delay_before_activate_added_delay[3:0]? ($floor(ns_to_nCK(tRP)/4) - 1): ($floor(ns_to_nCK(tRP)/4) - 1 + 1);
cmd_d[ANTICIPATE_PRECHARGE_SLOT] = {1'b0, CMD_PRE[2:0], next_bank, { {{ROW_BITS-4'd11}{1'b0}} , 1'b0 , next_row[9:0] } };
bank_status_d[next_bank] = 1'b0;
end //end of anticipate precharge
//anticipated bank is idle so do activate
else if(!bank_status_q[next_bank]) begin
else if(!bank_status_q[next_bank] && delay_before_activate_mask_q[next_bank][ANTICIPATE_ACTIVATE_SLOT] && delay_before_activate_counter_q[next_bank] == 0) begin
delay_before_read_added_delay = {{8{1'b1}}, delay_before_activate_mask_q[next_bank], {{ns_to_nCK(tRCD) % 3'd4}{1'b0}}};
delay_before_read_mask_d[next_bank] = delay_before_read_added_delay[3:0]? delay_before_read_added_delay[3:0]:delay_before_read_added_delay[7:4];
delay_before_read_counter_d[next_bank] = delay_before_read_added_delay[3:0]? ($floor(ns_to_nCK(tRCD) /4) - 1): ($floor(ns_to_nCK(tRCD) /4) - 1 + 1);
delay_before_write_added_delay = {{8{1'b1}}, delay_before_activate_mask_q[next_bank], {{ns_to_nCK(tRCD) % 3'd4}{1'b0}}};
delay_before_write_mask_d[next_bank] = delay_before_write_added_delay[3:0]? delay_before_write_added_delay[3:0]:delay_before_write_added_delay[7:4];
delay_before_write_counter_d[next_bank] = delay_before_write_added_delay[3:0]? ($floor(ns_to_nCK(tRCD)/4) - 1): ($floor(ns_to_nCK(tRCD)/4) - 1 + 1);
if(delay_before_activate_mask_q[next_bank][3:0] && delay_before_activate_counter_q[next_bank] == 0) begin
cmd_d[0] = {!delay_before_activate_mask_q[next_bank][0], CMD_ACT[2:0] , next_bank , request_row};
cmd_d[1] = {(delay_before_activate_mask_q[next_bank][1] ~^ delay_before_activate_mask_q[next_bank][0]), CMD_ACT[2:0] , next_bank , request_row};
cmd_d[2] = {(delay_before_activate_mask_q[next_bank][2] ~^ delay_before_activate_mask_q[next_bank][1]), CMD_ACT[2:0] , next_bank , request_row};
cmd_d[3] = {(delay_before_activate_mask_q[next_bank][3] ~^ delay_before_activate_mask_q[next_bank][2]), CMD_ACT[2:0] , next_bank , request_row}; //4 + 3 + 14 = 21
bank_status_d[next_bank] = 1'b1;
bank_active_row_d[next_bank] = request_row;
f_stage = 2;
end
cmd_d[ANTICIPATE_ACTIVATE_SLOT] = {!delay_before_activate_mask_q[next_bank][0], CMD_ACT[2:0] , next_bank , next_row};
bank_status_d[next_bank] = 1'b1;
bank_active_row_d[next_bank] = next_row;
end //end of anticipate activate
end //end of anticipate block
*/
end //end of if(request_pending_q) block
else begin
o_wb_stall_d = 0;
f_stage = 0;
end
end //end of always block
@ -748,7 +719,7 @@ module ddr3_controller #(
function[1:0] get_slot (input[3:0] cmd); //cmd can either be CMD_PRE,CMD_ACT, CMD_WR, CMD_RD
integer slot_number;
integer delay;
integer read_slot, write_slot, activate_slot, precharge_slot;
integer read_slot, write_slot, anticipate_activate_slot, anticipate_precharge_slot;
begin
// find read command slot number
delay = CL_nCK;
@ -764,29 +735,29 @@ module ddr3_controller #(
end
write_slot = slot_number[1:0];
// find activate command slot number
// find anticipate activate command slot number
if(CL_nCK > CWL_nCK) slot_number = read_slot;
else slot_number = write_slot;
delay = ns_to_nCK(tRCD);
for(slot_number = slot_number; delay != 0; delay = delay - 1) begin
slot_number[1:0] = slot_number[1:0] - 1'b1;
end
activate_slot = slot_number[1:0];
// if computed activate_slot is same with either write_slot or read_slot, decrement slot number until
while(activate_slot[1:0] == write_slot[1:0] || activate_slot[1:0] == read_slot[1:0]) begin
activate_slot[1:0] = activate_slot[1:0] - 1'b1;
anticipate_activate_slot = slot_number[1:0];
// if computed anticipate_activate_slot is same with either write_slot or read_slot, decrement slot number until
while(anticipate_activate_slot[1:0] == write_slot[1:0] || anticipate_activate_slot[1:0] == read_slot[1:0]) begin
anticipate_activate_slot[1:0] = anticipate_activate_slot[1:0] - 1'b1;
end
//the remaining slot will be for precharge command
precharge_slot = 0;
while(precharge_slot == write_slot || precharge_slot == read_slot || precharge_slot == activate_slot) begin
precharge_slot[1:0] = precharge_slot[1:0] - 1'b1;
anticipate_precharge_slot = 0;
while(anticipate_precharge_slot == write_slot || anticipate_precharge_slot == read_slot || anticipate_precharge_slot == anticipate_activate_slot) begin
anticipate_precharge_slot[1:0] = anticipate_precharge_slot[1:0] - 1'b1;
end
case(cmd)
CMD_RD: get_slot = read_slot;
CMD_WR: get_slot = write_slot;
CMD_ACT: get_slot = activate_slot;
CMD_PRE: get_slot = precharge_slot;
CMD_ACT: get_slot = anticipate_activate_slot;
CMD_PRE: get_slot = anticipate_precharge_slot;
endcase
end
endfunction
@ -850,8 +821,8 @@ module ddr3_controller #(
$display("READ_SLOT = %0d", READ_SLOT);
$display("WRITE_SLOT = %0d", WRITE_SLOT);
$display("ACTIVATE_SLOT = %0d", ACTIVATE_SLOT);
$display("PRECHARGE_SLOT = %0d", PRECHARGE_SLOT);
$display("ANTICIPATE_ACTIVATE_SLOT = %0d", ANTICIPATE_ACTIVATE_SLOT);
$display("ANTICIPATE_PRECHARGE_SLOT = %0d", ANTICIPATE_PRECHARGE_SLOT);
$display("\n\nDELAYS:");
$display("\tns_to_nCK(tRCD): %0d", ns_to_nCK(tRCD));
@ -1018,7 +989,7 @@ module ddr3_controller #(
always @* begin
//make sure each command has distinct slot number (except for read/write which can have the same or different slot number)
assert((WRITE_SLOT != ACTIVATE_SLOT != PRECHARGE_SLOT) && (READ_SLOT != ACTIVATE_SLOT != PRECHARGE_SLOT) );
assert((WRITE_SLOT != ANTICIPATE_ACTIVATE_SLOT != ANTICIPATE_PRECHARGE_SLOT) && (READ_SLOT != ANTICIPATE_ACTIVATE_SLOT != ANTICIPATE_PRECHARGE_SLOT) );
//make sure slot number for read command is correct
end
//create a formal assertion that says during refresh ack should be low always
@ -1060,7 +1031,8 @@ module ddr3_controller #(
if(f_index>1) assume(i_rst_n);
assume(i_wb_we == f_wb_inputs[f_index][24]);
assume(i_wb_addr == f_wb_inputs[f_index][23:0]);
cover(f_index == 13);
cover(f_index == 3);
end
`endif
endmodule