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hip: Add support for optional phase shifter clock to fractional MMCM module

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Signed-off-by: Alex Forencich <alex@alexforencich.com>
This commit is contained in:
Alex Forencich
2025-03-17 21:05:49 -07:00
parent d7e29a2b5c
commit 3624976f0e
1 changed files with 21 additions and 7 deletions
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28
rtl/hip/us/taxi_mmcm_frac.sv
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@@ -21,6 +21,8 @@ module taxi_mmcm_frac #(
parameter MMCM_INPUT_DIV = 1,
parameter MMCM_MULT = 8,
parameter MMCM_OUTPUT_DIV = MMCM_MULT,
parameter logic PSCLK_EN = 1'b0,
parameter PSCLK_DIV = MMCM_OUTPUT_DIV,
parameter logic EXTRA_MMCM = 1'b1,
parameter MMCM2_CASC_DIV = MMCM_OUTPUT_DIV,
parameter MMCM2_INPUT_DIV = 1,
@@ -41,12 +43,14 @@ module taxi_mmcm_frac #(
localparam MMCM_OUTPUT_CLK_PERIOD = MMCM_INPUT_CLK_PERIOD*MMCM_INPUT_DIV/MMCM_MULT*MMCM_OUTPUT_DIV;
localparam MMCM2_INPUT_CLK_PERIOD = MMCM_INPUT_CLK_PERIOD*MMCM_INPUT_DIV/MMCM_MULT*MMCM2_CASC_DIV;
localparam PSCLK_DIV_INT = PSCLK_EN ? PSCLK_DIV : MMCM_OUTPUT_DIV;
// 1 phase shifter tap is 1/56th of the VCO period
// To shift the frequency by OFFSET_NUM/OFFSET_DENOM, we need to shift the VCO output
// by OFFSET_NUM VCO periods (56*OFFSET_NUM taps) every OFFSET_DENOM VCO periods.
// Since the PSCLK is divided with respect to the VCO, rescale numerator by division factor
localparam DIR = OFFSET_NUM >= 0;
localparam NUM_1 = (DIR ? OFFSET_NUM : -OFFSET_NUM)*56*MMCM_OUTPUT_DIV;
localparam NUM_1 = (DIR ? OFFSET_NUM : -OFFSET_NUM)*56*PSCLK_DIV_INT;
localparam DENOM_1 = OFFSET_DENOM;
localparam MMCM_MIN_PSCLK_CYCLES = 12;
@@ -64,6 +68,8 @@ wire mmcm_clk_out;
wire mmcm_clk_bufg;
wire mmcm_offset_clk_out;
wire mmcm_offset_clk_bufg;
wire mmcm_ps_clk_out;
wire mmcm_ps_clk_bufg;
wire mmcm2_clkfb;
wire mmcm2_offset_clk_out;
@@ -74,11 +80,13 @@ assign locked = mmcm_locked && mmcm2_locked;
assign output_clk = mmcm_clk_bufg;
assign output_offset_clk = EXTRA_MMCM ? mmcm2_offset_clk_bufg : mmcm_offset_clk_bufg;
wire ps_clk = PSCLK_EN ? mmcm_ps_clk_bufg : output_clk;
logic [CNT_W-1:0] cnt_reg = '0;
logic ps_en_reg = 1'b0;
always_ff @(posedge output_clk) begin
always_ff @(posedge ps_clk) begin
ps_en_reg <= 1'b0;
if (cnt_reg + NUM_1 >= DENOM_1) begin
@@ -114,8 +122,8 @@ MMCME3_ADV #(
.CLKOUT1_DUTY_CYCLE(0.5),
.CLKOUT1_PHASE(0),
.CLKOUT1_USE_FINE_PS("TRUE"),
// Not used
.CLKOUT2_DIVIDE(1),
// phase shifter clock
.CLKOUT2_DIVIDE(PSCLK_EN ? PSCLK_DIV : 1),
.CLKOUT2_DUTY_CYCLE(0.5),
.CLKOUT2_PHASE(0),
.CLKOUT2_USE_FINE_PS("FALSE"),
@@ -167,8 +175,8 @@ clk_mmcm_inst (
// offset output
.CLKOUT1(mmcm_offset_clk_out),
.CLKOUT1B(),
// Not used
.CLKOUT2(),
// phase shifter clock
.CLKOUT2(mmcm_ps_clk_out),
.CLKOUT2B(),
// Not used
.CLKOUT3(),
@@ -193,7 +201,7 @@ clk_mmcm_inst (
// dynamic phase shift
.PSINCDEC(DIR ? 1'b0 : 1'b1),
.PSEN(ps_en_reg),
.PSCLK(output_clk),
.PSCLK(ps_clk),
.PSDONE(),
// locked output
.LOCKED(mmcm_locked),
@@ -217,6 +225,12 @@ mmcm_offset_clk_bufg_inst (
.O(mmcm_offset_clk_bufg)
);
BUFG
mmcm_ps_clk_bufg_inst (
.I(mmcm_ps_clk_out),
.O(mmcm_ps_clk_bufg)
);
if (EXTRA_MMCM) begin : extra_mmcm
// MMCM instance