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`include "parameters.vh"
module dll_toggler #(parameter CKE_WIDTH = 1, RANK_WIDTH = 1, DQ_WIDTH = 64, DRAM_CMD_SLOTS = 4,
DATA_BUF_ADDR_WIDTH = 5, DBUF_WIDTH = 4, DQ_BURST = 8)
(
input clk,
input rst,
input toggle_valid,
output reg dllt_done,
// ---------- DDR4 Signals ----------
output [7:0] mc_ACT_n, // DRAM ACT_n command signal for four DRAM clock cycles.
output [`ADDR_WIDTH*8-1:0] mc_ADR, // DRAM address. There are 8 bits in the fabric interface for each address bit on the DRAM bus.
output [`BANK_WIDTH*8-1:0] mc_BA, // DRAM bank address. 8 bits for each DRAM bank address.
output [`BG_WIDTH*8-1:0] mc_BG, // DRAM bank group address.
output [`CS_WIDTH*8-1:0] mc_CS_n, // DRAM CS_n
// NOTE: CKE is transmitted within another clock domain that is 4x faster than fabric clock.
output [`CKE_WIDTH*8-1:0] mc_CKE,
output clk_sel
);
wire [13:0] MR1_CONF = 14'b00001100000000;
reg [`ADDR_WIDTH*8-1:0] ADR_ns, ADR_r;
reg [`BANK_WIDTH*8-1:0] BA_ns, BA_r;
reg [`BG_WIDTH*8-1:0] BG_ns, BG_r;
reg [`CS_WIDTH*8-1:0] CS_n_ns, CS_n_r;
reg [`ODT_WIDTH*8-1:0] ODT_ns, ODT_r;
reg [`CKE_WIDTH*8-1:0] CKE_ns, CKE_r;
reg clk_sel_ns, clk_sel_r;
assign mc_ACT_n = {8{`HIGH}};
assign mc_ADR = ADR_r;
assign mc_BA = BA_r;
assign mc_BG = BG_r;
assign mc_CS_n = CS_n_r;
assign mc_CKE = CKE_r;
assign clk_sel = clk_sel_r;
// TODO we need to implement the following routine (TO TURN DLL OFF ONLY)
// 1 - Precharge all banks (IDLE STATE)
// 2 - Set MR1 A0 to 1 (DISABLE DLL), wait tMOD
// 3 - Enter self-refresh mode, wait until tCKSRE/tCKSRE_PAR
// 4 - Change clock frequency
// 5 - Wait at least tCKSRX (until clock signal stabilizes)
// 6 - Exit self-refresh mode, keep CKE high from now on
// if any ODT feature was enabled in self-ref. mode
// ODT signal must be LOW.
// 7 - Wait tXS and set mode registers to appropriate values
// (UG says that CL, CWL and WR may need to be updated),
// wait for another tMOD
localparam IDLE_S = 0;
localparam IDLE_WAIT_S = 1;
localparam SET_MR_1_S = 2;
localparam WAIT_MR_1_S = 3;
localparam ENTER_SELF_REF_S = 4;
localparam WAIT_ENTER_SELF_REF_S = 5;
localparam CHANGE_CLK_FREQ_S = 6;
localparam WAIT_CHANGE_CLK_FREQ_S = 7;
localparam EXIT_SELF_REF_S = 8;
localparam WAIT_EXIT_SELF_REF_S = 9;
localparam T_PRECHARGE = 5; // in terms of MC cycles (which is 4x less frequent than the DDR4)
localparam T_MOD = 24; // Max(24CK,15ns)
localparam T_CKSRE = 300; // Max(5CK,10ns)
localparam T_CKSRX = 300; // Max(5CK, 10ns) + additional room for clock to stabilize;
localparam T_XS = 1000;
reg[3:0] state_r, state_ns;
reg[9:0] wait_r, wait_ns;
integer adr_bit_i;
always @* begin
// Set bank and bank group signals
dllt_done = `LOW;
ADR_ns = {`ADDR_WIDTH*8{`HIGH}};
BG_ns = {`BG_WIDTH*8{`LOW}};
BA_ns = {`BANK_WIDTH*8{`LOW}};
CS_n_ns = {`CS_WIDTH*8{`HIGH}}; // by default we don't issue any commands
CKE_ns = CKE_r; // register this signal because it needs to be LOW during self-ref.
wait_ns = wait_r;
state_ns = state_r;
clk_sel_ns = clk_sel_r;
case (state_r)
IDLE_S: begin
if(toggle_valid) begin
CS_n_ns[1:0] = {2*`CS_WIDTH{`LOW}};
ADR_ns[`ADDR_WIDTH*8-3*8 +: 2] = {2{`LOW}}; // WE
ADR_ns[`ADDR_WIDTH*8-2*8 +: 2] = {2{`HIGH}}; // ~CAS
ADR_ns[`ADDR_WIDTH*8-8 +: 2] = {2{`LOW}}; // RAS
ADR_ns[10*8 +: 2] = {2{`HIGH}}; // Pre ALL
wait_ns = T_PRECHARGE;
state_ns = IDLE_WAIT_S;
end
end
IDLE_WAIT_S: begin
if(wait_r > 0)
wait_ns = wait_r - 1'b1;
else
state_ns = SET_MR_1_S;
end
SET_MR_1_S: begin
CS_n_ns[1:0] = {2*`CS_WIDTH{`LOW}};
ADR_ns[`ADDR_WIDTH*8-3*8 +: 2] = {2{`LOW}}; // WE
ADR_ns[`ADDR_WIDTH*8-2*8 +: 2] = {2{`LOW}}; // CAS
ADR_ns[`ADDR_WIDTH*8-8 +: 2] = {2{`LOW}}; // RAS
for(adr_bit_i = 0 ; adr_bit_i < 14 ; adr_bit_i = adr_bit_i + 1) begin
ADR_ns[adr_bit_i*8 +: 2] =
{2{MR1_CONF[adr_bit_i]}};
end
// Bank + Bank group bits indicate which register this MRS is writing to.
BA_ns[0 +: 2] = {2{`HIGH}}; // Select MR1
ADR_ns[0 +: 2] = {2{`LOW}}; // Set A0 to 0
state_ns = WAIT_MR_1_S;
wait_ns = T_MOD;
end
WAIT_MR_1_S: begin
if(wait_r > 0)
wait_ns = wait_r - 1'b1;
else
state_ns = ENTER_SELF_REF_S;
end
ENTER_SELF_REF_S: begin
CKE_ns = `LOW;
CS_n_ns[1:0] = {2*`CS_WIDTH{`LOW}};
ADR_ns[`ADDR_WIDTH*8-3*8 +: 2] = {2{`HIGH}}; // ~WE
ADR_ns[`ADDR_WIDTH*8-2*8 +: 2] = {2{`LOW}}; // CAS
ADR_ns[`ADDR_WIDTH*8-8 +: 2] = {2{`LOW}}; // RAS
state_ns = WAIT_ENTER_SELF_REF_S;
wait_ns = T_CKSRE;
end
WAIT_ENTER_SELF_REF_S: begin
if(wait_r > 0)
wait_ns = wait_r - 1'b1;
else begin
state_ns = CHANGE_CLK_FREQ_S;
end
end
CHANGE_CLK_FREQ_S: begin
clk_sel_ns = ~clk_sel_r;
wait_ns = T_CKSRX;
state_ns = WAIT_CHANGE_CLK_FREQ_S;
end
WAIT_CHANGE_CLK_FREQ_S: begin
if(wait_r > 0)
wait_ns = wait_r - 1'b1;
else begin
state_ns = EXIT_SELF_REF_S;
end
end
EXIT_SELF_REF_S: begin
CKE_ns = {`CKE_WIDTH*8{`HIGH}};
CS_n_ns[7:0] = {8*`CS_WIDTH{`HIGH}};
ADR_ns[`ADDR_WIDTH*8-3*8 +: 2] = {2{`HIGH}}; // ~WE
ADR_ns[`ADDR_WIDTH*8-2*8 +: 2] = {2{`HIGH}}; // CAS
ADR_ns[`ADDR_WIDTH*8-8 +: 2] = {2{`HIGH}}; // RAS
state_ns = WAIT_EXIT_SELF_REF_S;
wait_ns = T_XS;
end
WAIT_EXIT_SELF_REF_S: begin
CS_n_ns[7:0] = {8*`CS_WIDTH{`HIGH}};
if(wait_r > 0)
wait_ns = wait_r - 1'b1;
else begin
state_ns = IDLE_S;
dllt_done = `HIGH;
end
end
endcase
end
always @(posedge clk) begin
if(rst) begin
state_r <= IDLE_S;
wait_r <= `LOW;
clk_sel_r <= `LOW;
CKE_r <= {`CKE_WIDTH*8{`HIGH}};
ADR_r = {`ADDR_WIDTH*8{`LOW}};
BG_r = {`BG_WIDTH*8{`LOW}};
BA_r = {`BANK_WIDTH*8{`LOW}};
CS_n_r = {`CS_WIDTH*8{`HIGH}};
end
else begin
state_r <= state_ns;
wait_r <= wait_ns;
clk_sel_r <= clk_sel_ns;
CKE_r <= CKE_ns;
ADR_r <= ADR_ns;
BA_r <= BA_ns;
BG_r <= BG_ns;
CS_n_r <= CS_n_ns;
end
end
endmodule
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