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+//
+// Copyright 2011-2013 Ettus Research LLC
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program. If not, see <http://www.gnu.org/licenses/>.
+//
+
+//////////////////////////////////////////////////////////////////////////////////
+
+//this is a FIFO master interface for the FX3 in "slave fifo" mode.
+
+module gpif2_slave_fifo32
+#(
+ //sizes for fifo64 2 clock cascade fifos
+ parameter DATA_RX_FIFO_SIZE = 12, //max vita pkt size
+ parameter DATA_TX_FIFO_SIZE = 12, //max vita pkt size
+ parameter CTRL_RX_FIFO_SIZE = 5, //small resp packets
+ parameter CTRL_TX_FIFO_SIZE = 5, //small ctrl packets
+
+ //address constants for the endpoints
+ parameter ADDR_DATA_TX = 2'b00,
+ parameter ADDR_DATA_RX = 2'b01,
+ parameter ADDR_CTRL_TX = 2'b10,
+ parameter ADDR_CTRL_RX = 2'b11,
+
+ parameter END_WITH_COMMA = 0
+)
+ (
+ // GPIF signals
+ input gpif_clk,
+ input gpif_rst,
+ input gpif_enb,
+ inout [31:0] gpif_d,
+ input [3:0] gpif_ctl,
+ output reg sloe,
+ output reg slrd,
+ output reg slwr,
+ output slcs,
+ output reg pktend,
+ output reg [1:0] fifoadr,
+ // FIFO interfaces
+ input fifo_clk,
+ input fifo_rst,
+ // TX Data interface to DSP
+ output [63:0] tx_tdata, output tx_tlast, output tx_tvalid, input tx_tready,
+ // RX Data interface to DSP
+ input [63:0] rx_tdata, input rx_tlast, input rx_tvalid, output rx_tready,
+ // Incomming control interface
+ output [63:0] ctrl_tdata, output ctrl_tlast, output ctrl_tvalid, input ctrl_tready,
+ // Outgoing control interface
+ input [63:0] resp_tdata, input resp_tlast, input resp_tvalid, output resp_tready,
+ // Debug Signals
+ output [31:0] debug
+ );
+
+ reg fifo_nearly_full;
+ wire ctrl_tx_fifo_nearly_full, data_tx_fifo_nearly_full;
+ wire ctrl_tx_fifo_has_space, data_tx_fifo_has_space;
+
+
+ assign slcs = 1'b0;
+
+ //DMA FIFO ready and watermark flags
+ reg EP_READY, EP_READY1, EP_WMARK, EP_WMARK1;
+ always @(posedge gpif_clk) EP_READY <= gpif_ctl[0];
+ always @(posedge gpif_clk) EP_WMARK <= gpif_ctl[1];
+ always @(posedge gpif_clk) EP_READY1 <= EP_READY;
+ always @(posedge gpif_clk) EP_WMARK1 <= EP_WMARK;
+
+ // GPIF output data lines, tristate
+ reg [31:0] gpif_data_in, gpif_data_out;
+ always @(posedge gpif_clk) gpif_data_in <= gpif_d;
+ assign gpif_d = sloe ? gpif_data_out[31:0] : 32'bz;
+
+ // ////////////////////////////////////////////////////////////////////
+ // GPIF bus master state machine
+
+ wire wr_fifo_xfer, wr_fifo_eof;
+ wire [31:0] wr_fifo_data;
+ reg read_ready_go, write_ready_go;
+ reg wr_one, rd_one;
+
+ reg [3:0] state; //state machine current state
+ localparam STATE_IDLE = 0;
+ localparam STATE_THINK = 1;
+ localparam STATE_READ = 2;
+ localparam STATE_WRITE = 3;
+ localparam STATE_WAIT = 4;
+
+ reg [2:0] idle_cycles;
+ reg [1:0] last_addr, next_addr;
+ wire local_fifo_ready;
+
+ reg slrd1, slrd2, slrd3;
+
+ always @(posedge gpif_clk)
+ if (gpif_rst) begin
+ slrd1 <= 1;
+ slrd2 <= 1;
+ slrd3 <= 1;
+ end else begin
+ slrd1 <= slrd;
+ slrd2 <= slrd1;
+ slrd3 <= slrd2;
+ end
+
+ wire RD_VALID = ~slrd3;
+ wire RD_LAST = slrd2;
+ wire WR_VALID = (EP_WMARK1 || !wr_one);
+
+ // //////////////////////////////////////////////////////////////
+ // FX2 slave FIFO bus master state machine
+ //
+ always @(posedge gpif_clk)
+ if(gpif_rst) begin
+ state <= STATE_IDLE;
+ sloe <= 0;
+ slrd <= 1;
+ slwr <= 1;
+ pktend <= 1;
+ gpif_data_out <= 32'b0;
+ idle_cycles <= 0;
+ fifoadr <= 0;
+ wr_one <= 1'b0;
+ rd_one <= 1'b0;
+ last_addr <= 2'b0;
+ end
+ else if (gpif_enb) begin
+ case (state)
+
+ //
+ // Increment fifoadr to point at next thread, set all strobes to idle,
+ //
+ STATE_IDLE: begin
+ sloe <= 0;
+ slrd <= 1;
+ slwr <= 1;
+ pktend <= 1;
+ gpif_data_out <= 32'b0;
+ fifoadr <= next_addr;
+ state <= STATE_WAIT;
+ idle_cycles <= 0;
+ end
+
+ //
+ // If the current thread we are pointing at (fifoadr) can not immediately proceed
+ // then quickly move to the next thread. Once we are pointing at a thread that can proceed locally
+ // wait for 8 clock cycles to allow fifoadr to propogate to FX3, and corresponding flag state to
+ // propogate back to FPGA and through resampling flops. At this point transition to STATE_THINK
+ // to evaluate remote flag.
+ //
+ STATE_WAIT: begin
+ // Current thread can proceed locally
+ if (local_fifo_ready) begin
+ idle_cycles <= idle_cycles + 1'b1;
+ if (idle_cycles == 3'b111) state <= STATE_THINK;
+ end
+ // ....move onto next thread.
+ else begin
+ idle_cycles <= 3'b0;
+ fifoadr <= fifoadr + 2'b1;
+ end
+ end
+
+ //
+ // If there is a read to start, assert SLRD and SLOE and transition to STATE_READ.
+ // If there is a write to perform, set flags that says there is the possibility to do at least
+ // one write (wr_one) and transition to STATE_WRITE.
+ // If the FX3 has nothing ready for this thread return immediately to STATE_IDLE.
+ //
+ STATE_THINK: begin
+ if (EP_READY1 && read_ready_go) begin
+ state <= STATE_READ;
+ slrd <= 0;
+ rd_one <= 0;
+ end
+ else if (EP_READY1 && write_ready_go) begin
+ state <= STATE_WRITE;
+ sloe <= 1;
+ wr_one <= 1'b0;
+ end
+ else begin
+ state <= STATE_IDLE;
+ end
+
+ idle_cycles <= 0;
+ last_addr <= fifoadr;
+ end
+
+ // If flag rd_one is set (armed 5 cycles after slrd goes initialy assrted) and RD_VALID has gone deasserted
+ // (meaning that the watermark deasserted 5 clock cycles ago) transition to STATE_IDLE.
+ // If watermark deasserted 2 cycles ago de-assert slrd ...read data is still traveling in the pipeline.
+ // Whilst RD_VALID stays asserted keep the rd_one flag armed.
+ STATE_READ: begin
+ if (rd_one && ~RD_VALID) state <= STATE_IDLE;
+ if (~EP_WMARK1 | fifo_nearly_full) slrd <= 1;
+ if (RD_VALID) rd_one <= 1'b1;
+ end
+
+ // If local FIFO goes empty or tlast is set then transition to STATE_IDLE
+ // Push local FIFO data out onto GPIF data bus.
+ // if local FIFO has valid data then assert slwr
+ // if local FIFO assertes tlast then assert pktend
+ // If WR_VALID asserted (because wr_one already asserted in the first cycle in this state)
+ // now clear wr_one (watermark will keep WR_VALID asserted from now on if this is a burst).
+ //
+ STATE_WRITE: begin
+ if (~wr_fifo_xfer || wr_fifo_eof) state <= STATE_IDLE;
+ gpif_data_out <= wr_fifo_data;
+ slwr <= ~wr_fifo_xfer;
+ pktend <= ~wr_fifo_eof;
+ if (WR_VALID) wr_one <= 1'b1;
+ end
+
+ default: state <= STATE_IDLE;
+ endcase
+ end
+
+ // ///////////////////////////////////////////////////////////////////
+ // fifo signal assignments and enables
+
+ //output from fifos - ready to xfer
+ wire data_tx_tready, ctrl_tx_tready;
+ wire ctrl_rx_tvalid, data_rx_tvalid;
+
+ //Priority encoding for the the next address to service:
+ //The next address to service is based on the readiness
+ //of the internal fifos and last serviced fairness metric.
+/* -----\/----- EXCLUDED -----\/-----
+ always @(posedge gpif_clk) next_addr <=
+ ((ctrl_rx_tvalid && (last_addr != ADDR_CTRL_RX))? ADDR_CTRL_RX :
+ ((ctrl_tx_fifo_has_space && (last_addr != ADDR_CTRL_TX))? ADDR_CTRL_TX :
+ ((data_rx_tvalid && (last_addr != ADDR_DATA_RX))? ADDR_DATA_RX :
+ ((data_tx_fifo_has_space && (last_addr != ADDR_DATA_TX))? ADDR_DATA_TX :
+ (fifoadr + 2'b1)
+ ))));
+ -----/\----- EXCLUDED -----/\----- */
+ always @(posedge gpif_clk) next_addr <= (fifoadr + 2'b1);
+
+
+ //Help the FPGA search to only look for addrs that the FPGA is ready for
+ assign local_fifo_ready =
+ (ctrl_rx_tvalid && (fifoadr == ADDR_CTRL_RX)) ||
+ (ctrl_tx_fifo_has_space && (fifoadr == ADDR_CTRL_TX)) ||
+ (data_rx_tvalid && (fifoadr == ADDR_DATA_RX)) ||
+ (data_tx_fifo_has_space && (fifoadr == ADDR_DATA_TX));
+
+ always @(posedge gpif_clk) fifo_nearly_full <=
+ (ctrl_tx_fifo_nearly_full && (fifoadr == ADDR_CTRL_TX)) ||
+ (data_tx_fifo_nearly_full && (fifoadr == ADDR_DATA_TX));
+
+ always @(posedge gpif_clk) read_ready_go <=
+ (ctrl_tx_fifo_has_space && (fifoadr == ADDR_CTRL_TX)) ||
+ (data_tx_fifo_has_space && (fifoadr == ADDR_DATA_TX));
+
+ always @(posedge gpif_clk) write_ready_go <=
+ (ctrl_rx_tvalid && (fifoadr == ADDR_CTRL_RX)) ||
+ (data_rx_tvalid && (fifoadr == ADDR_DATA_RX));
+
+ //fifo xfer enable
+ wire data_rx_tready = (state == STATE_WRITE) && (fifoadr == ADDR_DATA_RX) && WR_VALID;
+ wire ctrl_rx_tready = (state == STATE_WRITE) && (fifoadr == ADDR_CTRL_RX) && WR_VALID;
+ wire data_tx_tvalid = (state == STATE_READ) && (fifoadr == ADDR_DATA_TX) && RD_VALID;
+ wire ctrl_tx_tvalid = (state == STATE_READ) && (fifoadr == ADDR_CTRL_TX) && RD_VALID;
+
+ //outputs from rx fifo paths
+ wire ctrl_rx_tlast, data_rx_tlast;
+ wire [31:0] ctrl_rx_tdata, data_rx_tdata;
+
+ //mux rx outputs for gpif state machine
+ assign wr_fifo_xfer = (fifoadr == ADDR_CTRL_RX)? (ctrl_rx_tvalid && ctrl_rx_tready) : (data_rx_tvalid && data_rx_tready);
+ assign wr_fifo_eof = wr_fifo_xfer && ((fifoadr == ADDR_CTRL_RX)? ctrl_rx_tlast : data_rx_tlast);
+ assign wr_fifo_data = (fifoadr == ADDR_CTRL_RX)? ctrl_rx_tdata : data_rx_tdata;
+
+ wire ctrl_bus_error, tx_bus_error;
+
+ // ////////////////////////////////////////////////////////////////////
+ // TX Data Path
+
+ gpif2_to_fifo64 #(.FIFO_SIZE(DATA_TX_FIFO_SIZE)) gpif2_to_fifo64_tx(
+ .gpif_clk(gpif_clk), .gpif_rst(gpif_rst),
+ .i_tdata(gpif_data_in), .i_tlast(RD_LAST), .i_tvalid(data_tx_tvalid), .i_tready(data_tx_tready),
+ .fifo_clk(fifo_clk), .fifo_rst(fifo_rst),
+ .fifo_nearly_full(data_tx_fifo_nearly_full), .fifo_has_space(data_tx_fifo_has_space),
+ .o_tdata(tx_tdata), .o_tlast(tx_tlast), .o_tvalid(tx_tvalid), .o_tready(tx_tready),
+ .bus_error(tx_bus_error), .debug()
+ );
+
+ // ////////////////////////////////////////////
+ // RX Data Path
+
+ fifo64_to_gpif2 #(.FIFO_SIZE(DATA_RX_FIFO_SIZE)) fifo64_to_gpif2_rx(
+ .fifo_clk(fifo_clk), .fifo_rst(fifo_rst),
+ .i_tdata(rx_tdata), .i_tlast(rx_tlast), .i_tvalid(rx_tvalid), .i_tready(rx_tready),
+ .gpif_clk(gpif_clk), .gpif_rst(gpif_rst),
+ .o_tdata(data_rx_tdata), .o_tlast(data_rx_tlast), .o_tvalid(data_rx_tvalid), .o_tready(data_rx_tready)
+ );
+
+ // ////////////////////////////////////////////////////////////////////
+ // CTRL path
+
+ gpif2_to_fifo64 #(.FIFO_SIZE(CTRL_TX_FIFO_SIZE)) gpif2_to_fifo64_ctrl(
+ .gpif_clk(gpif_clk), .gpif_rst(gpif_rst),
+ .i_tdata(gpif_data_in), .i_tlast(RD_LAST), .i_tvalid(ctrl_tx_tvalid), .i_tready(ctrl_tx_tready),
+ .fifo_clk(fifo_clk), .fifo_rst(fifo_rst),
+ .fifo_nearly_full(ctrl_tx_fifo_nearly_full), .fifo_has_space(ctrl_tx_fifo_has_space),
+ .o_tdata(ctrl_tdata), .o_tlast(ctrl_tlast), .o_tvalid(ctrl_tvalid), .o_tready(ctrl_tready),
+ .bus_error(ctrl_bus_error), .debug()
+ );
+
+ // ////////////////////////////////////////////////////////////////////
+ // RESP path
+
+ fifo64_to_gpif2 #(.FIFO_SIZE(CTRL_RX_FIFO_SIZE)) fifo64_to_gpif2_resp(
+ .fifo_clk(fifo_clk), .fifo_rst(fifo_rst),
+ .i_tdata(resp_tdata), .i_tlast(resp_tlast), .i_tvalid(resp_tvalid), .i_tready(resp_tready),
+ .gpif_clk(gpif_clk), .gpif_rst(gpif_rst),
+ .o_tdata(ctrl_rx_tdata), .o_tlast(ctrl_rx_tlast), .o_tvalid(ctrl_rx_tvalid), .o_tready(ctrl_rx_tready)
+ );
+
+ // ////////////////////////////////////////////
+ // DEBUG
+
+
+
+endmodule // gpif2_slave_fifo32
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