corundum/fpga/common/rtl/mqnic_ptp_clock.v

// SPDX-License-Identifier: BSD-2-Clause-Views
/*
 * Copyright (c) 2021-2023 The Regents of the University of California
 */

// Language: Verilog 2001

`resetall
`timescale 1ns / 1ps
`default_nettype none

/*
 * PTP hardware clock
 */
module mqnic_ptp_clock #
(
    parameter PTP_CLK_PERIOD_NS_NUM = 4,
    parameter PTP_CLK_PERIOD_NS_DENOM = 1,
    parameter PTP_CLOCK_PIPELINE = 0,
    parameter PTP_CLOCK_CDC_PIPELINE = 0,
    parameter PTP_USE_SAMPLE_CLOCK = 0,
    parameter PTP_PEROUT_ENABLE = 0,
    parameter PTP_PEROUT_COUNT = 1,
    parameter REG_ADDR_WIDTH = 7,
    parameter REG_DATA_WIDTH = 32,
    parameter REG_STRB_WIDTH = (REG_DATA_WIDTH/8),
    parameter RB_BASE_ADDR = 0,
    parameter RB_NEXT_PTR = 0
)
(
    input  wire                       clk,
    input  wire                       rst,

    /*
     * Register interface
     */
    input  wire [REG_ADDR_WIDTH-1:0]  reg_wr_addr,
    input  wire [REG_DATA_WIDTH-1:0]  reg_wr_data,
    input  wire [REG_STRB_WIDTH-1:0]  reg_wr_strb,
    input  wire                       reg_wr_en,
    output wire                       reg_wr_wait,
    output wire                       reg_wr_ack,
    input  wire [REG_ADDR_WIDTH-1:0]  reg_rd_addr,
    input  wire                       reg_rd_en,
    output wire [REG_DATA_WIDTH-1:0]  reg_rd_data,
    output wire                       reg_rd_wait,
    output wire                       reg_rd_ack,

    /*
     * PTP clock
     */
    input  wire                       ptp_clk,
    input  wire                       ptp_rst,
    input  wire                       ptp_sample_clk,
    output wire                       ptp_pps,
    output wire                       ptp_pps_str,
    output wire [95:0]                ptp_ts_96,
    output wire                       ptp_ts_step,
    output wire                       ptp_sync_pps,
    output wire [95:0]                ptp_sync_ts_96,
    output wire                       ptp_sync_ts_step
);

parameter PTP_FNS_WIDTH = 32;

parameter PTP_CLK_PERIOD_NS = PTP_CLK_PERIOD_NS_NUM / PTP_CLK_PERIOD_NS_DENOM;
parameter PTP_CLK_PERIOD_NS_REM = PTP_CLK_PERIOD_NS_NUM - PTP_CLK_PERIOD_NS*PTP_CLK_PERIOD_NS_DENOM;
parameter PTP_CLK_PERIOD_FNS = (PTP_CLK_PERIOD_NS_REM * {32'd1, {PTP_FNS_WIDTH{1'b0}}}) / PTP_CLK_PERIOD_NS_DENOM;
parameter PTP_CLK_PERIOD_FNS_REM = (PTP_CLK_PERIOD_NS_REM * {32'd1, {PTP_FNS_WIDTH{1'b0}}}) - PTP_CLK_PERIOD_FNS*PTP_CLK_PERIOD_NS_DENOM;

parameter PTP_PERIOD_NS_WIDTH = $clog2(PTP_CLK_PERIOD_NS+1) + 2;
parameter PTP_OFFSET_NS_WIDTH = 30;

localparam RBB = RB_BASE_ADDR & {REG_ADDR_WIDTH{1'b1}};

// check configuration
initial begin
    if (REG_DATA_WIDTH != 32) begin
        $error("Error: Register interface width must be 32 (instance %m)");
        $finish;
    end

    if (REG_STRB_WIDTH * 8 != REG_DATA_WIDTH) begin
        $error("Error: Register interface requires byte (8-bit) granularity (instance %m)");
        $finish;
    end

    if (REG_ADDR_WIDTH < 7) begin
        $error("Error: Register address width too narrow (instance %m)");
        $finish;
    end

    if (RB_NEXT_PTR >= RB_BASE_ADDR && RB_NEXT_PTR < RB_BASE_ADDR + 7'h60) begin
        $error("Error: RB_NEXT_PTR overlaps block (instance %m)");
        $finish;
    end
end

// control registers
reg reg_wr_ack_reg = 1'b0;
reg [REG_DATA_WIDTH-1:0] reg_rd_data_reg = 0;
reg reg_rd_ack_reg = 1'b0;

reg [95:0] get_ptp_ts_96_reg = 0;
reg [95:0] set_ptp_ts_96_reg = 0;
reg set_ptp_ts_96_valid_reg = 0;
reg [PTP_PERIOD_NS_WIDTH-1:0] set_ptp_period_ns_reg = PTP_CLK_PERIOD_NS;
reg [PTP_FNS_WIDTH-1:0] set_ptp_period_fns_reg = PTP_CLK_PERIOD_FNS;
reg set_ptp_period_valid_reg = 0;
reg [PTP_OFFSET_NS_WIDTH-1:0] set_ptp_offset_ns_reg = 0;
reg [PTP_FNS_WIDTH-1:0] set_ptp_offset_fns_reg = 0;
reg [15:0] set_ptp_offset_count_reg = 0;
reg set_ptp_offset_valid_reg = 0;
wire set_ptp_offset_active;

assign reg_wr_wait = 1'b0;
assign reg_wr_ack = reg_wr_ack_reg;
assign reg_rd_data = reg_rd_data_reg;
assign reg_rd_wait = 1'b0;
assign reg_rd_ack = reg_rd_ack_reg;

always @(posedge clk) begin
    reg_wr_ack_reg <= 1'b0;
    reg_rd_data_reg <= 0;
    reg_rd_ack_reg <= 1'b0;

    if (reg_wr_en && !reg_wr_ack_reg) begin
        // write operation
        reg_wr_ack_reg <= 1'b1;
        case ({reg_wr_addr >> 2, 2'b00})
            // PHC
            RBB+7'h30: set_ptp_ts_96_reg[15:0] <= reg_wr_data;  // PTP set fns
            RBB+7'h34: set_ptp_ts_96_reg[45:16] <= reg_wr_data; // PTP set ns
            RBB+7'h38: set_ptp_ts_96_reg[79:48] <= reg_wr_data; // PTP set sec l
            RBB+7'h3C: begin
                // PTP set sec h
                set_ptp_ts_96_reg[95:80] <= reg_wr_data;
                set_ptp_ts_96_valid_reg <= !set_ptp_ts_96_valid_reg;
            end
            RBB+7'h40: set_ptp_period_fns_reg <= reg_wr_data; // PTP period fns
            RBB+7'h44: begin
                // PTP period ns
                set_ptp_period_ns_reg <= reg_wr_data;
                set_ptp_period_valid_reg <= !set_ptp_period_valid_reg;
            end
            RBB+7'h50: set_ptp_offset_fns_reg <= reg_wr_data; // PTP offset fns
            RBB+7'h54: set_ptp_offset_ns_reg <= reg_wr_data;  // PTP offset ns
            RBB+7'h58: begin
                // PTP offset count
                set_ptp_offset_count_reg <= reg_wr_data;
                set_ptp_offset_valid_reg <= !set_ptp_offset_valid_reg;
            end
            default: reg_wr_ack_reg <= 1'b0;
        endcase
    end

    if (reg_rd_en && !reg_rd_ack_reg) begin
        // read operation
        reg_rd_ack_reg <= 1'b1;
        case ({reg_rd_addr >> 2, 2'b00})
            // PHC
            RBB+7'h00: reg_rd_data_reg <= 32'h0000C080;  // PHC: Type
            RBB+7'h04: reg_rd_data_reg <= 32'h00000100;  // PHC: Version
            RBB+7'h08: reg_rd_data_reg <= RB_NEXT_PTR;   // PHC: Next header
            RBB+7'h0C: begin
                // PHC features
                reg_rd_data_reg[7:0] <= PTP_PEROUT_ENABLE ? PTP_PEROUT_COUNT : 0;
                reg_rd_data_reg[15:8] <= 0;
                reg_rd_data_reg[23:16] <= 0;
                reg_rd_data_reg[31:24] <= 0;
            end
            RBB+7'h10: reg_rd_data_reg <= ptp_sync_ts_96[15:0];    // PTP cur fns
            RBB+7'h14: reg_rd_data_reg <= ptp_sync_ts_96[45:16];   // PTP cur ns
            RBB+7'h18: reg_rd_data_reg <= ptp_sync_ts_96[79:48];   // PTP cur sec l
            RBB+7'h1C: reg_rd_data_reg <= ptp_sync_ts_96[95:80];   // PTP cur sec h
            RBB+7'h20: begin
                // PTP get fns
                get_ptp_ts_96_reg <= ptp_sync_ts_96;
                reg_rd_data_reg <= ptp_sync_ts_96[15:0];
            end
            RBB+7'h24: reg_rd_data_reg <= get_ptp_ts_96_reg[45:16]; // PTP get ns
            RBB+7'h28: reg_rd_data_reg <= get_ptp_ts_96_reg[79:48]; // PTP get sec l
            RBB+7'h2C: reg_rd_data_reg <= get_ptp_ts_96_reg[95:80]; // PTP get sec h
            RBB+7'h30: reg_rd_data_reg <= set_ptp_ts_96_reg[15:0];  // PTP set fns
            RBB+7'h34: reg_rd_data_reg <= set_ptp_ts_96_reg[45:16]; // PTP set ns
            RBB+7'h38: reg_rd_data_reg <= set_ptp_ts_96_reg[79:48]; // PTP set sec l
            RBB+7'h3C: reg_rd_data_reg <= set_ptp_ts_96_reg[95:80]; // PTP set sec h
            RBB+7'h40: reg_rd_data_reg <= set_ptp_period_fns_reg;   // PTP period fns
            RBB+7'h44: reg_rd_data_reg <= set_ptp_period_ns_reg;    // PTP period ns
            RBB+7'h48: reg_rd_data_reg <= PTP_CLK_PERIOD_FNS;       // PTP nom period fns
            RBB+7'h4C: reg_rd_data_reg <= PTP_CLK_PERIOD_NS;        // PTP nom period ns
            RBB+7'h50: reg_rd_data_reg <= set_ptp_offset_fns_reg;   // PTP offset fns
            RBB+7'h54: reg_rd_data_reg <= set_ptp_offset_ns_reg;    // PTP offset ns
            RBB+7'h58: reg_rd_data_reg <= set_ptp_offset_count_reg; // PTP offset count
            RBB+7'h5C: reg_rd_data_reg <= set_ptp_offset_active;    // PTP offset status
            default: reg_rd_ack_reg <= 1'b0;
        endcase
    end

    if (rst) begin
        reg_wr_ack_reg <= 1'b0;
        reg_rd_ack_reg <= 1'b0;

        set_ptp_period_ns_reg <= PTP_CLK_PERIOD_NS;
        set_ptp_period_fns_reg <= PTP_CLK_PERIOD_FNS;
    end
end

(* shreg_extract = "no" *)
reg set_ptp_ts_96_valid_sync_1_reg = 1'b0;
(* shreg_extract = "no" *)
reg set_ptp_ts_96_valid_sync_2_reg = 1'b0;
(* shreg_extract = "no" *)
reg set_ptp_ts_96_valid_sync_3_reg = 1'b0;

(* shreg_extract = "no" *)
reg set_ptp_period_valid_sync_1_reg = 1'b0;
(* shreg_extract = "no" *)
reg set_ptp_period_valid_sync_2_reg = 1'b0;
(* shreg_extract = "no" *)
reg set_ptp_period_valid_sync_3_reg = 1'b0;

(* shreg_extract = "no" *)
reg set_ptp_offset_valid_sync_1_reg = 1'b0;
(* shreg_extract = "no" *)
reg set_ptp_offset_valid_sync_2_reg = 1'b0;
(* shreg_extract = "no" *)
reg set_ptp_offset_valid_sync_3_reg = 1'b0;

always @(posedge ptp_clk) begin
    set_ptp_ts_96_valid_sync_1_reg <= set_ptp_ts_96_valid_reg;
    set_ptp_ts_96_valid_sync_2_reg <= set_ptp_ts_96_valid_sync_1_reg;
    set_ptp_ts_96_valid_sync_3_reg <= set_ptp_ts_96_valid_sync_2_reg;

    set_ptp_period_valid_sync_1_reg <= set_ptp_period_valid_reg;
    set_ptp_period_valid_sync_2_reg <= set_ptp_period_valid_sync_1_reg;
    set_ptp_period_valid_sync_3_reg <= set_ptp_period_valid_sync_2_reg;

    set_ptp_offset_valid_sync_1_reg <= set_ptp_offset_valid_reg;
    set_ptp_offset_valid_sync_2_reg <= set_ptp_offset_valid_sync_1_reg;
    set_ptp_offset_valid_sync_3_reg <= set_ptp_offset_valid_sync_2_reg;
end

// PTP clock
ptp_clock #(
    .PERIOD_NS_WIDTH(PTP_PERIOD_NS_WIDTH),
    .OFFSET_NS_WIDTH(PTP_OFFSET_NS_WIDTH),
    .FNS_WIDTH(PTP_FNS_WIDTH),
    .PERIOD_NS(PTP_CLK_PERIOD_NS),
    .PERIOD_FNS(PTP_CLK_PERIOD_FNS),
    .DRIFT_ENABLE(0),
    .DRIFT_NS(0),
    .DRIFT_FNS(PTP_CLK_PERIOD_FNS_REM),
    .DRIFT_RATE(PTP_CLK_PERIOD_NS_DENOM),
    .PIPELINE_OUTPUT(PTP_CLOCK_PIPELINE)
)
ptp_clock_inst (
    .clk(ptp_clk),
    .rst(ptp_rst),

    /*
     * Timestamp inputs for synchronization
     */
    .input_ts_96(set_ptp_ts_96_reg),
    .input_ts_96_valid(set_ptp_ts_96_valid_sync_2_reg ^ set_ptp_ts_96_valid_sync_3_reg),
    .input_ts_64(0),
    .input_ts_64_valid(1'b0),

    /*
     * Period adjustment
     */
    .input_period_ns(set_ptp_period_ns_reg),
    .input_period_fns(set_ptp_period_fns_reg),
    .input_period_valid(set_ptp_period_valid_sync_2_reg ^ set_ptp_period_valid_sync_3_reg),

    /*
     * Offset adjustment
     */
    .input_adj_ns(set_ptp_offset_ns_reg),
    .input_adj_fns(set_ptp_offset_fns_reg),
    .input_adj_count(set_ptp_offset_count_reg),
    .input_adj_valid(set_ptp_offset_valid_sync_2_reg ^ set_ptp_offset_valid_sync_3_reg),
    // .input_adj_active(set_ptp_offset_active),

    /*
     * Drift adjustment
     */
    .input_drift_ns(0),
    .input_drift_fns(0),
    .input_drift_rate(0),
    .input_drift_valid(0),

    /*
     * Timestamp outputs
     */
    .output_ts_96(ptp_ts_96),
    .output_ts_64(),
    .output_ts_step(ptp_ts_step),

    /*
     * PPS output
     */
    .output_pps(ptp_pps)
);

// stretched PPS output
localparam PPS_CNT_PERIOD = (64'd500_000_000*PTP_CLK_PERIOD_NS_DENOM)/PTP_CLK_PERIOD_NS_NUM;

reg [$clog2(PPS_CNT_PERIOD)-1:0] pps_counter_reg = 0;
reg pps_str_reg = 0;

always @(posedge ptp_clk) begin
    pps_str_reg <= 1'b0;

    if (ptp_pps) begin
        pps_counter_reg <= PPS_CNT_PERIOD;
        pps_str_reg <= 1'b1;
    end else if (pps_counter_reg > 0) begin
        pps_counter_reg <= pps_counter_reg - 1;
        pps_str_reg <= 1'b1;
    end
end

assign ptp_pps_str = pps_str_reg;

// sync to core clock domain
ptp_clock_cdc #(
    .TS_WIDTH(96),
    .NS_WIDTH(PTP_PERIOD_NS_WIDTH),
    .FNS_WIDTH(16),
    .USE_SAMPLE_CLOCK(PTP_USE_SAMPLE_CLOCK),
    .PIPELINE_OUTPUT(PTP_CLOCK_CDC_PIPELINE)
)
ptp_cdc_inst (
    .input_clk(ptp_clk),
    .input_rst(ptp_rst),
    .output_clk(clk),
    .output_rst(rst),
    .sample_clk(ptp_sample_clk),
    .input_ts(ptp_ts_96),
    .input_ts_step(ptp_ts_step),
    .output_ts(ptp_sync_ts_96),
    .output_ts_step(ptp_sync_ts_step),
    .output_pps(ptp_sync_pps),
    .locked()
);

endmodule

`resetall