diff options
Diffstat (limited to 'src/rtl')
| -rw-r--r-- | src/rtl/fmc_arbiter.v | 401 |
1 files changed, 228 insertions, 173 deletions
diff --git a/src/rtl/fmc_arbiter.v b/src/rtl/fmc_arbiter.v index 037d640..376e85b 100644 --- a/src/rtl/fmc_arbiter.v +++ b/src/rtl/fmc_arbiter.v @@ -7,7 +7,7 @@ // // // Author: Pavel Shatov -// Copyright (c) 2015, 2018 NORDUnet A/S All rights reserved. +// Copyright (c) 2015, 2018-2019 NORDUnet A/S All rights reserved. // // Redistribution and use in source and binary forms, with or without // modification, are permitted provided that the following conditions @@ -38,174 +38,208 @@ //====================================================================== module fmc_arbiter - ( - // fmc bus - fmc_a, fmc_d, - fmc_ne1, fmc_nl, fmc_nwe, fmc_noe, fmc_nwait, - - // system clock - sys_clk, - - // user bus - sys_addr, - sys_wr_en, - sys_data_out, - sys_rd_en, - sys_data_in - ); - - - // - // Parameters - // - parameter NUM_ADDR_BITS = 22; - - - // - // Ports - // - input wire [NUM_ADDR_BITS-1:0] fmc_a; - inout wire [ 31:0] fmc_d; - input wire fmc_ne1; - input wire fmc_nl; - input wire fmc_nwe; - input wire fmc_noe; - output wire fmc_nwait; - - input wire sys_clk; - - output wire [NUM_ADDR_BITS-1:0] sys_addr; - output wire sys_wr_en; - output wire [ 31:0] sys_data_out; - output wire sys_rd_en; - input wire [ 31:0] sys_data_in; - - - // - // Data Bus PHY - // - - /* PHY is needed to control bi-directional data bus. */ - - wire [31: 0] fmc_d_ro; // value read from pins (receiver output) - wire [31: 0] fmc_d_di; // value drives onto pins (driver input) - - fmc_d_phy # - ( - .BUS_WIDTH(32) - ) - d_phy - ( - .buf_io(fmc_d), // <-- connect directly to top-level bi-dir port - .buf_di(fmc_d_di), - .buf_ro(fmc_d_ro), - .buf_t(fmc_noe) // <-- bus direction is controlled by STM32 - ); +( + // fmc bus + fmc_a, fmc_d, + fmc_ne1, fmc_nl, fmc_nwe, fmc_noe, fmc_nwait, + + // system clock, i/o clock + sys_clk, + io_clk, + + // user bus + sys_addr, + sys_wr_en, + sys_data_out, + sys_rd_en, + sys_data_in +); + + + // + // Parameters + // + parameter NUM_ADDR_BITS = 24; + + + // + // Ports + // + input wire [NUM_ADDR_BITS-1:0] fmc_a; + inout wire [ 31:0] fmc_d; + input wire fmc_ne1; + input wire fmc_nl; + input wire fmc_nwe; + input wire fmc_noe; + output wire fmc_nwait; + + input wire sys_clk; + input wire io_clk; + + output wire [NUM_ADDR_BITS-1:0] sys_addr; + output wire sys_wr_en; + output wire [ 31:0] sys_data_out; + output wire sys_rd_en; + input wire [ 31:0] sys_data_in; + + + // + // Data Bus PHY + // + + /* PHY is needed to control bi-directional data bus. */ + + wire [31: 0] fmc_d_ro; // value read from pins (receiver output) + wire [31: 0] fmc_d_di; // value drives onto pins (driver input) + + fmc_d_phy # + ( + .BUS_WIDTH(32) + ) + d_phy + ( + //.buf_io (fmc_d_swapped), // <-- connect directly to top-level bi-dir port + + // we just swap the order of wires in the bi-directional data bus + .buf_io({fmc_d[7:0], fmc_d[15:8], fmc_d[23:16], fmc_d[31:24]}), + + .buf_di (fmc_d_di), // driver input (from FPGA to STM32) + .buf_ro (fmc_d_ro), // receiver output (from STM32 to FPGA) + .buf_t (fmc_noe) // <-- bus direction is controlled by STM32 + ); + + + // + // CDC Helper Signals + // + reg cdc_slow_ff = 1'b0; + reg cdc_fast_ff = 1'b0; + + always @(posedge io_clk) cdc_slow_ff <= ~cdc_slow_ff; + always @(posedge sys_clk) cdc_fast_ff <= cdc_slow_ff; + + reg cdc_same_edges; + + always @(posedge sys_clk) + cdc_same_edges <= cdc_slow_ff ^ cdc_fast_ff; + // - // Two-Stage Synchronizer + // Synchronizer // - (* SHREG_EXTRACT="NO" *) (* IOB="FALSE" *) reg [23: 0] fmc_a_ff1; - (* SHREG_EXTRACT="NO" *) reg [23: 0] fmc_a_ff2; + (* SHREG_EXTRACT="NO" *) (* IOB="FALSE" *) reg [NUM_ADDR_BITS-1:0] fmc_a_ff1; + (* SHREG_EXTRACT="NO" *) reg [NUM_ADDR_BITS-1:0] fmc_a_ff2; + (* SHREG_EXTRACT="NO" *) reg [NUM_ADDR_BITS-1:0] fmc_a_ff3; - (* SHREG_EXTRACT="NO" *) (* IOB="TRUE" *) reg [31: 0] fmc_d_ro_ff1; - (* SHREG_EXTRACT="NO" *) reg [31: 0] fmc_d_ro_ff2; + (* SHREG_EXTRACT="NO" *) (* IOB="TRUE" *) reg [ 32-1:0] fmc_d_ro_ff1; + (* SHREG_EXTRACT="NO" *) reg [ 32-1:0] fmc_d_ro_ff2; + (* SHREG_EXTRACT="NO" *) reg [ 32-1:0] fmc_d_ro_ff3; (* SHREG_EXTRACT="NO" *) (* IOB="FALSE" *) reg fmc_ne1_ff1; (* SHREG_EXTRACT="NO" *) reg fmc_ne1_ff2; + (* SHREG_EXTRACT="NO" *) reg fmc_ne1_ff3; (* SHREG_EXTRACT="NO" *) (* IOB="FALSE" *) reg fmc_nwe_ff1; (* SHREG_EXTRACT="NO" *) reg fmc_nwe_ff2; + (* SHREG_EXTRACT="NO" *) reg fmc_nwe_ff3; (* SHREG_EXTRACT="NO" *) (* IOB="FALSE" *) reg fmc_nl_ff1; (* SHREG_EXTRACT="NO" *) reg fmc_nl_ff2; + (* SHREG_EXTRACT="NO" *) reg fmc_nl_ff3; + + wire [NUM_ADDR_BITS-1:0] fmc_a_sync_sys = fmc_a_ff3; + wire [ 32-1:0] fmc_d_ro_sync_sys = fmc_d_ro_ff3; + wire fmc_ne1_sync_sys = fmc_ne1_ff3; + wire fmc_nwe_sync_sys = fmc_nwe_ff3; + wire fmc_nl_sync_sys = fmc_nl_ff3; + + always @(posedge io_clk) begin + // + {fmc_a_ff2, fmc_a_ff1} <= {fmc_a_ff1, fmc_a}; + {fmc_d_ro_ff2, fmc_d_ro_ff1} <= {fmc_d_ro_ff1, fmc_d_ro}; + {fmc_ne1_ff2, fmc_ne1_ff1} <= {fmc_ne1_ff1, fmc_ne1}; + {fmc_nwe_ff2, fmc_nwe_ff1} <= {fmc_nwe_ff1, fmc_nwe}; + {fmc_nl_ff2, fmc_nl_ff1} <= {fmc_nl_ff1, fmc_nl}; + // + end + + always @(posedge sys_clk) + // + if (cdc_same_edges) begin + fmc_a_ff3 <= fmc_a_ff2; + fmc_d_ro_ff3 <= fmc_d_ro_ff2; + fmc_ne1_ff3 <= fmc_ne1_ff2; + fmc_nwe_ff3 <= fmc_nwe_ff2; + fmc_nl_ff3 <= fmc_nl_ff2; + end + + + // + // FSM + // + localparam FSM_STATE_IDLE = 4'd00; - wire [23: 0] fmc_a_sync = fmc_a_ff2; - wire [31: 0] fmc_d_ro_sync = fmc_d_ro_ff2; - wire fmc_ne1_sync = fmc_ne1_ff2; - wire fmc_nwe_sync = fmc_nwe_ff2; - wire fmc_nl_sync = fmc_nl_ff2; - - always @(posedge sys_clk) begin - fmc_a_ff1 <= fmc_a; - fmc_a_ff2 <= fmc_a_ff1; - - fmc_d_ro_ff1 <= fmc_d_ro; - fmc_d_ro_ff2 <= fmc_d_ro_ff1; - - fmc_ne1_ff1 <= fmc_ne1; - fmc_ne1_ff2 <= fmc_ne1_ff1; - - fmc_nwe_ff1 <= fmc_nwe; - fmc_nwe_ff2 <= fmc_nwe_ff1; - - fmc_nl_ff1 <= fmc_nl; - fmc_nl_ff2 <= fmc_nl_ff1; - end - - - // - // FSM - // - localparam FSM_STATE_IDLE = 4'd0; - - localparam FSM_STATE_WRITE_START = 4'd1; - localparam FSM_STATE_WRITE_LATENCY_1 = 4'd2; - localparam FSM_STATE_WRITE_LATENCY_2 = 4'd3; - localparam FSM_STATE_WRITE_LATENCY_3 = 4'd4; - localparam FSM_STATE_WRITE_LATENCY_4 = 4'd5; - localparam FSM_STATE_WRITE_STOP = 4'd6; - - localparam FSM_STATE_READ_START = 4'd7; - localparam FSM_STATE_READ_LATENCY_1 = 4'd8; - localparam FSM_STATE_READ_STOP = 4'd9; - - reg [ 3: 0] fsm_state = FSM_STATE_IDLE; - reg [ 3: 0] fsm_state_next; - - always @(posedge sys_clk) - // - fsm_state <= fsm_state_next; - - - // - // FSM Transition Logic - // - always @* - // - if (fmc_ne1_sync) fsm_state_next = FSM_STATE_IDLE; - else case (fsm_state) - FSM_STATE_IDLE: fsm_state_next = !fmc_nwe_sync ? FSM_STATE_WRITE_START : FSM_STATE_READ_START; - FSM_STATE_WRITE_START: fsm_state_next = FSM_STATE_WRITE_LATENCY_1; - FSM_STATE_WRITE_LATENCY_1: fsm_state_next = FSM_STATE_WRITE_LATENCY_2; - FSM_STATE_WRITE_LATENCY_2: fsm_state_next = FSM_STATE_WRITE_LATENCY_3; - FSM_STATE_WRITE_LATENCY_3: fsm_state_next = FSM_STATE_WRITE_LATENCY_4; - FSM_STATE_WRITE_LATENCY_4, - FSM_STATE_WRITE_STOP: fsm_state_next = FSM_STATE_WRITE_STOP; - FSM_STATE_READ_START: fsm_state_next = FSM_STATE_READ_LATENCY_1; - FSM_STATE_READ_LATENCY_1, - FSM_STATE_READ_STOP: fsm_state_next = FSM_STATE_READ_STOP; - default: fsm_state_next = FSM_STATE_IDLE; - endcase + localparam FSM_STATE_WRITE_START = 4'd01; + localparam FSM_STATE_WRITE_LATENCY_1 = 4'd02; + localparam FSM_STATE_WRITE_LATENCY_2 = 4'd03; + localparam FSM_STATE_WRITE_LATENCY_3 = 4'd04; + localparam FSM_STATE_WRITE_LATENCY_4 = 4'd05; + localparam FSM_STATE_WRITE_LATENCY_5 = 4'd06; + localparam FSM_STATE_WRITE_LATENCY_6 = 4'd07; + localparam FSM_STATE_WRITE_STOP = 4'd08; + localparam FSM_STATE_READ_START = 4'd09; + localparam FSM_STATE_READ_LATENCY_1 = 4'd10; + localparam FSM_STATE_READ_LATENCY_2 = 4'd11; + localparam FSM_STATE_READ_LATENCY_3 = 4'd12; + localparam FSM_STATE_READ_STOP = 4'd13; + + reg [ 3: 0] fsm_state = FSM_STATE_IDLE; + reg [ 3: 0] fsm_state_next; + + always @(posedge sys_clk) + // + fsm_state <= fsm_state_next; + + + // + // FSM Transition Logic + // + always @* + // + if (!cdc_same_edges) fsm_state_next = fsm_state; + else begin + // + if (fmc_ne1_sync_sys) fsm_state_next = FSM_STATE_IDLE; + else case (fsm_state) + FSM_STATE_IDLE: fsm_state_next = !fmc_nwe_sync_sys ? FSM_STATE_WRITE_START : FSM_STATE_READ_START; + FSM_STATE_WRITE_START: fsm_state_next = FSM_STATE_WRITE_LATENCY_1; + FSM_STATE_WRITE_LATENCY_1: fsm_state_next = FSM_STATE_WRITE_LATENCY_2; + FSM_STATE_WRITE_LATENCY_2: fsm_state_next = FSM_STATE_WRITE_LATENCY_3; + FSM_STATE_WRITE_LATENCY_3: fsm_state_next = FSM_STATE_WRITE_LATENCY_4; + FSM_STATE_WRITE_LATENCY_4: fsm_state_next = FSM_STATE_WRITE_LATENCY_5; + FSM_STATE_WRITE_LATENCY_5: fsm_state_next = FSM_STATE_WRITE_LATENCY_6; + FSM_STATE_WRITE_LATENCY_6, + FSM_STATE_WRITE_STOP: fsm_state_next = FSM_STATE_WRITE_STOP; + FSM_STATE_READ_START: fsm_state_next = FSM_STATE_READ_LATENCY_1; + FSM_STATE_READ_LATENCY_1: fsm_state_next = FSM_STATE_READ_LATENCY_2; + FSM_STATE_READ_LATENCY_2: fsm_state_next = FSM_STATE_READ_LATENCY_3; + FSM_STATE_READ_LATENCY_3, + FSM_STATE_READ_STOP: fsm_state_next = FSM_STATE_READ_STOP; + default: fsm_state_next = FSM_STATE_IDLE; + endcase + // + end + // // Output Data Latch // + reg [31:0] sys_data_in_latch_fast; (* IOB="TRUE" *) - reg [31:0] sys_data_in_latch; + reg [31:0] sys_data_in_latch_slow; - assign fmc_d_di = sys_data_in_latch; - - - // - // Address Latch - // - always @(posedge sys_clk) - // - if (!fmc_ne1_sync && !fmc_nl_sync) - // - sys_addr_reg <= fmc_a_sync; + assign fmc_d_di = sys_data_in_latch_slow; // @@ -223,51 +257,72 @@ module fmc_arbiter // + // Address Latch + // + always @(posedge sys_clk) + // + if (!fmc_ne1_sync_sys && !fmc_nl_sync_sys && cdc_same_edges) + sys_addr_reg <= fmc_a_sync_sys; + + + // // Write Enable Logic // - always @(posedge sys_clk) - // - case (fsm_state) - FSM_STATE_WRITE_LATENCY_4: sys_wr_en_reg <= 1'b1; - default: sys_wr_en_reg <= 1'b0; - endcase + always @(posedge sys_clk) + // + case (fsm_state) + FSM_STATE_WRITE_LATENCY_6: sys_wr_en_reg <= ~cdc_same_edges; + default: sys_wr_en_reg <= 1'b0; + endcase + - // // Read Enable Logic // - always @(posedge sys_clk) - // - case (fsm_state_next) - FSM_STATE_READ_START: sys_rd_en_reg <= 1'b1; - default: sys_rd_en_reg <= 1'b0; - endcase + always @(posedge sys_clk) + // + case (fsm_state_next) + FSM_STATE_READ_START: sys_rd_en_reg <= cdc_same_edges; + default: sys_rd_en_reg <= 1'b0; + endcase // - // Output Data Latch + // Output Data Latches // - always @(posedge sys_clk) - // - case (fsm_state) - FSM_STATE_READ_LATENCY_1: sys_data_in_latch <= sys_data_in; - endcase + always @(posedge sys_clk) + // + case (fsm_state) + FSM_STATE_READ_LATENCY_2: + if (cdc_same_edges) + sys_data_in_latch_fast <= sys_data_in; + endcase + + always @(negedge io_clk) + // + case (fsm_state) + FSM_STATE_READ_LATENCY_3: + sys_data_in_latch_slow <= sys_data_in_latch_fast; + endcase + // // Input Data Latch // - always @(posedge sys_clk) - // - case (fsm_state) - FSM_STATE_WRITE_LATENCY_4: sys_data_out_reg <= fmc_d_ro_sync; - endcase + always @(posedge sys_clk) + // + case (fsm_state) + FSM_STATE_WRITE_LATENCY_6: + if (!cdc_same_edges) + sys_data_out_reg <= fmc_d_ro_sync_sys; + endcase // // Unused NWAIT tieoff // - assign fmc_nwait = 1'b0; + assign fmc_nwait = 1'b0; endmodule |