From a67abc2f80d5181d607abb8663d13f6dd8ec1b0b Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Joachim=20Stro=CC=88mbergson?= Date: Sun, 1 Feb 2015 09:12:26 +0100 Subject: Removed trailing whitespace and ^M. --- rtl/src/verilog/cdc_bus_pulse.v | 216 +++++++-------- rtl/src/verilog/core_selector.v | 220 +++++++-------- rtl/src/verilog/eim_arbiter.v | 486 +++++++++++++++++----------------- rtl/src/verilog/eim_da_phy.v | 72 ++--- rtl/src/verilog/novena_baseline_top.v | 208 +++++++-------- rtl/src/verilog/novena_clkmgr.v | 162 ++++++------ 6 files changed, 682 insertions(+), 682 deletions(-) (limited to 'rtl') diff --git a/rtl/src/verilog/cdc_bus_pulse.v b/rtl/src/verilog/cdc_bus_pulse.v index 104bfa5..631506c 100644 --- a/rtl/src/verilog/cdc_bus_pulse.v +++ b/rtl/src/verilog/cdc_bus_pulse.v @@ -1,114 +1,114 @@ -`timescale 1ns / 1ps - -module cdc_bus_pulse - ( - src_clk, src_din, src_req, - dst_clk, dst_dout, dst_pulse - ); - - /* This module is based on design suggested on page 27 of an article titled - "Clock Domain Crossing (CDC) Design & Verification Techniques Using SystemVerilog" - by Clifford E. Cummings (Sunburst Design, Inc.) - */ - - // - // Parameters - // - parameter DATA_WIDTH = 32; // width of data bus - - - // - // Ports - // - input wire src_clk; // source domain clock - input wire [DATA_WIDTH-1:0] src_din; // data from source clock domain - input wire src_req; // start transfer pulse from source clock domain - - input wire dst_clk; // destination domain clock - output wire [DATA_WIDTH-1:0] dst_dout; // data to destination clock domain - output wire dst_pulse; // transfer done pulse to destination clock domain - - - // - // Source Side Registers - // - reg src_ff = 1'b0; // transfer request flag - reg [DATA_WIDTH-1:0] src_latch = {DATA_WIDTH{1'bX}}; // source data buffer - - - // - // Source Request Handler - // - always @(posedge src_clk) - // - if (src_req) begin // transfer request pulse? - src_ff <= ~src_ff; // toggle transfer request flag... - src_latch <= src_din; // ... and capture data in source buffer - end - - - // - // Source -> Destination Flag Sync Logic - // - - /* ISE may decide to infer SRL here, so we explicitly instantiate slice registers. */ - - wire flag_sync_first; // first FF output - wire flag_sync_second; // second FF output - wire flag_sync_third; // third FF output - wire flag_sync_pulse; // flag toggle detector output - - FDCE ff_sync_first - ( - .C (dst_clk), +`timescale 1ns / 1ps + +module cdc_bus_pulse + ( + src_clk, src_din, src_req, + dst_clk, dst_dout, dst_pulse + ); + + /* This module is based on design suggested on page 27 of an article titled + "Clock Domain Crossing (CDC) Design & Verification Techniques Using SystemVerilog" + by Clifford E. Cummings (Sunburst Design, Inc.) + */ + + // + // Parameters + // + parameter DATA_WIDTH = 32; // width of data bus + + + // + // Ports + // + input wire src_clk; // source domain clock + input wire [DATA_WIDTH-1:0] src_din; // data from source clock domain + input wire src_req; // start transfer pulse from source clock domain + + input wire dst_clk; // destination domain clock + output wire [DATA_WIDTH-1:0] dst_dout; // data to destination clock domain + output wire dst_pulse; // transfer done pulse to destination clock domain + + + // + // Source Side Registers + // + reg src_ff = 1'b0; // transfer request flag + reg [DATA_WIDTH-1:0] src_latch = {DATA_WIDTH{1'bX}}; // source data buffer + + + // + // Source Request Handler + // + always @(posedge src_clk) + // + if (src_req) begin // transfer request pulse? + src_ff <= ~src_ff; // toggle transfer request flag... + src_latch <= src_din; // ... and capture data in source buffer + end + + + // + // Source -> Destination Flag Sync Logic + // + + /* ISE may decide to infer SRL here, so we explicitly instantiate slice registers. */ + + wire flag_sync_first; // first FF output + wire flag_sync_second; // second FF output + wire flag_sync_third; // third FF output + wire flag_sync_pulse; // flag toggle detector output + + FDCE ff_sync_first + ( + .C (dst_clk), .D (src_ff), // capture flag from another clock domain - .Q (flag_sync_first), // metastability can occur here - .CLR (1'b0), + .Q (flag_sync_first), // metastability can occur here + .CLR (1'b0), .CE (1'b1) - ); - FDCE ff_sync_second - ( - .C (dst_clk), + ); + FDCE ff_sync_second + ( + .C (dst_clk), .D (flag_sync_first), // synchronize captured flag to remove metastability - .Q (flag_sync_second), // and pass it to another flip-flop - .CLR (1'b0), + .Q (flag_sync_second), // and pass it to another flip-flop + .CLR (1'b0), .CE (1'b1) - ); - FDCE ff_sync_third - ( - .C (dst_clk), + ); + FDCE ff_sync_third + ( + .C (dst_clk), .D (flag_sync_second), // delay synchronized flag in another flip-flip, because we need - .Q (flag_sync_third), // two synchronized flag values (current and delayed) to detect its change - .CLR (1'b0), + .Q (flag_sync_third), // two synchronized flag values (current and delayed) to detect its change + .CLR (1'b0), .CE (1'b1) - ); - - // when delayed flag value differs from its current value, it was changed - // by the source side, so there must have been a transfer request - assign flag_sync_pulse = flag_sync_second ^ flag_sync_third; - - - // - // Destination Side Registers - // - reg dst_pulse_reg = 1'b0; // transfer done flag - reg [DATA_WIDTH-1:0] dst_latch = {DATA_WIDTH{1'bX}}; // destination data buffer - - assign dst_pulse = dst_pulse_reg; - assign dst_dout = dst_latch; - - // - // Destination Request Handler - // - always @(posedge dst_clk) begin - // - dst_pulse_reg <= flag_sync_pulse; // generate pulse if flag change was detected - // - if (flag_sync_pulse) dst_latch <= src_latch; // by the time destination side receives synchronized - // // flag value, data should be stable, we can safely - // // capture and store it in the destination buffer - // - end - - -endmodule + ); + + // when delayed flag value differs from its current value, it was changed + // by the source side, so there must have been a transfer request + assign flag_sync_pulse = flag_sync_second ^ flag_sync_third; + + + // + // Destination Side Registers + // + reg dst_pulse_reg = 1'b0; // transfer done flag + reg [DATA_WIDTH-1:0] dst_latch = {DATA_WIDTH{1'bX}}; // destination data buffer + + assign dst_pulse = dst_pulse_reg; + assign dst_dout = dst_latch; + + // + // Destination Request Handler + // + always @(posedge dst_clk) begin + // + dst_pulse_reg <= flag_sync_pulse; // generate pulse if flag change was detected + // + if (flag_sync_pulse) dst_latch <= src_latch; // by the time destination side receives synchronized + // // flag value, data should be stable, we can safely + // // capture and store it in the destination buffer + // + end + + +endmodule diff --git a/rtl/src/verilog/core_selector.v b/rtl/src/verilog/core_selector.v index 2db2a05..eb6551a 100644 --- a/rtl/src/verilog/core_selector.v +++ b/rtl/src/verilog/core_selector.v @@ -1,112 +1,112 @@ -`timescale 1ns / 1ps - -module core_selector - ( - sys_clk, sys_rst, +`timescale 1ns / 1ps + +module core_selector + ( + sys_clk, sys_rst, sys_eim_addr, sys_eim_wr, sys_eim_rd, - sys_eim_dout, sys_eim_din - ); - - // - // Ports - // - input wire sys_clk; - input wire sys_rst; - - input wire [13: 0] sys_eim_addr; - input wire sys_eim_wr; + sys_eim_dout, sys_eim_din + ); + + // + // Ports + // + input wire sys_clk; + input wire sys_rst; + + input wire [13: 0] sys_eim_addr; + input wire sys_eim_wr; input wire sys_eim_rd; - input wire [31: 0] sys_eim_dout; - output wire [31: 0] sys_eim_din; - - - // - // Internal Registers - // - reg [31: 0] reg_x = {32{1'b0}}; - reg [31: 0] reg_y = {32{1'b0}}; - reg [15: 0] reg_ctl = {16{1'b0}}; - reg [31: 0] sys_eim_din_reg = {32{1'b0}}; - - - // - // Parameters - // - localparam ADDER_BASE_ADDR = 12'h321; // upper 12 bits of address - localparam ADDER_OFFSET_REG_X = 2'd0; // X - localparam ADDER_OFFSET_REG_Y = 2'd1; // Y - localparam ADDER_OFFSET_REG_Z = 2'd2; // Z - localparam ADDER_OFFSET_REG_SC = 2'd3; // {STATUS, CONTROL} - - - /* This flag detects whether adder core is being addressed. */ - wire eim_access_adder = (sys_eim_addr[13:2] == ADDER_BASE_ADDR) ? 1'b1 : 1'b0; - - /* These flags detect whether write or read access is requested. */ - wire eim_access_write = sys_eim_wr & eim_access_adder; - wire eim_access_read = sys_eim_rd & eim_access_adder; - - - // - // Write Request Handler - // - always @(posedge sys_clk) - // - if (sys_rst) begin - reg_x <= {32{1'b0}}; - reg_y <= {32{1'b0}}; - reg_ctl <= {16{1'b0}}; - end else if (eim_access_write) begin - // - case (sys_eim_addr[1:0]) - ADDER_OFFSET_REG_X: reg_x <= sys_eim_dout; - ADDER_OFFSET_REG_Y: reg_y <= sys_eim_dout; - ADDER_OFFSET_REG_SC: reg_ctl <= sys_eim_dout[15: 0]; - endcase - // - end - - - // - // Read Request Handler - // - wire [31: 0] reg_z; - wire [15: 0] reg_sts; - - always @(posedge sys_clk) - // - if (sys_rst) sys_eim_din_reg <= {32{1'b0}}; - // - else if (eim_access_read) begin - // - case (sys_eim_addr[1:0]) - ADDER_OFFSET_REG_X: sys_eim_din_reg <= reg_x; - ADDER_OFFSET_REG_Y: sys_eim_din_reg <= reg_y; - ADDER_OFFSET_REG_Z: sys_eim_din_reg <= reg_z; - ADDER_OFFSET_REG_SC: sys_eim_din_reg <= {reg_sts, reg_ctl}; - endcase - // - end - - assign sys_eim_din = sys_eim_din_reg; - - - // - // Demo Adder Core - // - demo_adder adder_core - ( - .clk (sys_clk), - .rst (sys_rst), - - .x (reg_x), - .y (reg_y), - .z (reg_z), - - .ctl (reg_ctl), - .sts (reg_sts) - ); - - - -endmodule + input wire [31: 0] sys_eim_dout; + output wire [31: 0] sys_eim_din; + + + // + // Internal Registers + // + reg [31: 0] reg_x = {32{1'b0}}; + reg [31: 0] reg_y = {32{1'b0}}; + reg [15: 0] reg_ctl = {16{1'b0}}; + reg [31: 0] sys_eim_din_reg = {32{1'b0}}; + + + // + // Parameters + // + localparam ADDER_BASE_ADDR = 12'h321; // upper 12 bits of address + localparam ADDER_OFFSET_REG_X = 2'd0; // X + localparam ADDER_OFFSET_REG_Y = 2'd1; // Y + localparam ADDER_OFFSET_REG_Z = 2'd2; // Z + localparam ADDER_OFFSET_REG_SC = 2'd3; // {STATUS, CONTROL} + + + /* This flag detects whether adder core is being addressed. */ + wire eim_access_adder = (sys_eim_addr[13:2] == ADDER_BASE_ADDR) ? 1'b1 : 1'b0; + + /* These flags detect whether write or read access is requested. */ + wire eim_access_write = sys_eim_wr & eim_access_adder; + wire eim_access_read = sys_eim_rd & eim_access_adder; + + + // + // Write Request Handler + // + always @(posedge sys_clk) + // + if (sys_rst) begin + reg_x <= {32{1'b0}}; + reg_y <= {32{1'b0}}; + reg_ctl <= {16{1'b0}}; + end else if (eim_access_write) begin + // + case (sys_eim_addr[1:0]) + ADDER_OFFSET_REG_X: reg_x <= sys_eim_dout; + ADDER_OFFSET_REG_Y: reg_y <= sys_eim_dout; + ADDER_OFFSET_REG_SC: reg_ctl <= sys_eim_dout[15: 0]; + endcase + // + end + + + // + // Read Request Handler + // + wire [31: 0] reg_z; + wire [15: 0] reg_sts; + + always @(posedge sys_clk) + // + if (sys_rst) sys_eim_din_reg <= {32{1'b0}}; + // + else if (eim_access_read) begin + // + case (sys_eim_addr[1:0]) + ADDER_OFFSET_REG_X: sys_eim_din_reg <= reg_x; + ADDER_OFFSET_REG_Y: sys_eim_din_reg <= reg_y; + ADDER_OFFSET_REG_Z: sys_eim_din_reg <= reg_z; + ADDER_OFFSET_REG_SC: sys_eim_din_reg <= {reg_sts, reg_ctl}; + endcase + // + end + + assign sys_eim_din = sys_eim_din_reg; + + + // + // Demo Adder Core + // + demo_adder adder_core + ( + .clk (sys_clk), + .rst (sys_rst), + + .x (reg_x), + .y (reg_y), + .z (reg_z), + + .ctl (reg_ctl), + .sts (reg_sts) + ); + + + +endmodule diff --git a/rtl/src/verilog/eim_arbiter.v b/rtl/src/verilog/eim_arbiter.v index 247ff69..1e39629 100644 --- a/rtl/src/verilog/eim_arbiter.v +++ b/rtl/src/verilog/eim_arbiter.v @@ -1,247 +1,247 @@ -`timescale 1ns / 1ps - -module eim_arbiter - ( +`timescale 1ns / 1ps + +module eim_arbiter + ( eim_bclk, eim_cs0_n, eim_da, eim_lba_n, eim_wr_n, - eim_oe_n, eim_wait_n, - - sys_clk, - sys_addr, - sys_wren, sys_data_out, - sys_rden, sys_data_in - ); - - - // - // Ports - // - input wire eim_bclk; // | eim bus - input wire eim_cs0_n; // | + eim_oe_n, eim_wait_n, + + sys_clk, + sys_addr, + sys_wren, sys_data_out, + sys_rden, sys_data_in + ); + + + // + // Ports + // + input wire eim_bclk; // | eim bus + input wire eim_cs0_n; // | inout wire [15: 0] eim_da; // | - input wire eim_lba_n; // | + input wire eim_lba_n; // | input wire eim_wr_n; // | - input wire eim_oe_n; // | - output wire eim_wait_n; // | - - input wire sys_clk; // system clock - - output wire [13: 0] sys_addr; // | user bus - output wire sys_wren; // | - output wire [31: 0] sys_data_out; // | - output wire sys_rden; // | - input wire [31: 0] sys_data_in; // | - - - // - // Data/Address PHY - // - - /* PHY is needed to control bi-directional address/data bus. */ - - wire [15: 0] da_ro; // value read from pins - reg [15: 0] da_di; // value drives onto pins - - eim_da_phy da_phy - ( - .buf_io (eim_da), // <-- connect directly top-level port - .buf_di (da_di), - .buf_ro (da_ro), - .buf_t (eim_oe_n) // <-- driven by EIM directly - ); - - - // - // FSM - // - localparam EIM_FSM_STATE_INIT = 5'b0_0_000; // arbiter is idle - - localparam EIM_FSM_STATE_WRITE_START = 5'b1_1_000; // got address to write at - localparam EIM_FSM_STATE_WRITE_LSB = 5'b1_1_001; // got lower 16 bits of data to write - localparam EIM_FSM_STATE_WRITE_MSB = 5'b1_1_010; // got upper 16 bits of data to write - localparam EIM_FSM_STATE_WRITE_WAIT = 5'b1_1_100; // request to user-side logic sent - localparam EIM_FSM_STATE_WRITE_DONE = 5'b1_1_111; // user-side logic acknowledged transaction - - localparam EIM_FSM_STATE_READ_START = 5'b1_0_000; // got address to read from - localparam EIM_FSM_STATE_READ_WAIT = 5'b1_0_100; // request to user-side logic sent - localparam EIM_FSM_STATE_READ_READY = 5'b1_0_011; // got acknowledge from user logic - localparam EIM_FSM_STATE_READ_LSB = 5'b1_0_001; // returned lower 16 bits to master - localparam EIM_FSM_STATE_READ_MSB = 5'b1_0_010; // returned upper 16 bits to master - localparam EIM_FSM_STATE_READ_DONE = 5'b1_0_111; // transaction complete - - reg [ 4: 0] eim_fsm_state = EIM_FSM_STATE_INIT; // fsm state - reg [13: 0] eim_addr_latch = {14{1'bX}}; // transaction address - reg [15: 0] eim_write_lsb_latch = {16{1'bX}}; // lower 16 bits of data to write - - /* These flags are used to wake up from INIT state. */ - wire eim_write_start_flag = (eim_lba_n == 1'b0) && (eim_wr_n == 1'b0) && (da_ro[1:0] == 2'b00); - wire eim_read_start_flag = (eim_lba_n == 1'b0) && (eim_wr_n == 1'b1) && (da_ro[1:0] == 2'b00); - - /* These are transaction response flag and data from user-side logic. */ - wire eim_user_ack; - wire [31: 0] eim_user_data; - - /* FSM is reset whenever Chip Select is de-asserted. */ - - // - // FSM Transition Logic - // - always @(posedge eim_bclk or posedge eim_cs0_n) begin - // - if (eim_cs0_n == 1'b1) eim_fsm_state <= EIM_FSM_STATE_INIT; - // - else begin - // - case (eim_fsm_state) - // - // INIT -> WRITE, INIT -> READ - // - EIM_FSM_STATE_INIT: begin - if (eim_write_start_flag) eim_fsm_state <= EIM_FSM_STATE_WRITE_START; - if (eim_read_start_flag) eim_fsm_state <= EIM_FSM_STATE_READ_START; - end - // - // WRITE - // - EIM_FSM_STATE_WRITE_START: eim_fsm_state <= EIM_FSM_STATE_WRITE_LSB; - // - EIM_FSM_STATE_WRITE_LSB: eim_fsm_state <= EIM_FSM_STATE_WRITE_MSB; - // - EIM_FSM_STATE_WRITE_MSB: eim_fsm_state <= EIM_FSM_STATE_WRITE_WAIT; - // - EIM_FSM_STATE_WRITE_WAIT: - if (eim_user_ack) eim_fsm_state <= EIM_FSM_STATE_WRITE_DONE; - // - EIM_FSM_STATE_WRITE_DONE: eim_fsm_state <= EIM_FSM_STATE_INIT; - // - // READ - // - EIM_FSM_STATE_READ_START: eim_fsm_state <= EIM_FSM_STATE_READ_WAIT; - // - EIM_FSM_STATE_READ_WAIT: - if (eim_user_ack) eim_fsm_state <= EIM_FSM_STATE_READ_READY; - // - EIM_FSM_STATE_READ_READY: eim_fsm_state <= EIM_FSM_STATE_READ_LSB; - // - EIM_FSM_STATE_READ_LSB: eim_fsm_state <= EIM_FSM_STATE_READ_MSB; - // - EIM_FSM_STATE_READ_MSB: eim_fsm_state <= EIM_FSM_STATE_READ_DONE; - // - EIM_FSM_STATE_READ_DONE: eim_fsm_state <= EIM_FSM_STATE_INIT; - // - // - // - default: eim_fsm_state <= EIM_FSM_STATE_INIT; - // - endcase - // - end - // - end - - - // - // Address Latch - // - always @(posedge eim_bclk) - // - if ((eim_fsm_state == EIM_FSM_STATE_INIT) && (eim_write_start_flag || eim_read_start_flag)) - eim_addr_latch <= da_ro[15:2]; - - - // - // Additional Write Logic - // - always @(posedge eim_bclk) - // - if (eim_fsm_state == EIM_FSM_STATE_WRITE_START) - eim_write_lsb_latch <= da_ro; - - - // - // Additional Read Logic - // - - /* Note that this stuff operates on falling clock edge, because the cpu - * samples our bi-directional data bus on rising clock edge. - */ - - always @(negedge eim_bclk or posedge eim_cs0_n) - // - if (eim_cs0_n == 1'b1) da_di <= {16{1'bX}}; // don't care what to drive - else begin - // - if (eim_fsm_state == EIM_FSM_STATE_READ_LSB) da_di <= eim_user_data[15: 0]; // drive lower 16 bits at first... - if (eim_fsm_state == EIM_FSM_STATE_READ_MSB) da_di <= eim_user_data[31:16]; // ...then drive upper 16 bits - // - end - - - // - // Wait Logic - // - - /* Note that this stuff operates on falling clock edge, because the cpu - * samples our WAIT_N flag on rising clock edge. - */ - - reg eim_wait_reg = 1'b0; - - always @(negedge eim_bclk or posedge eim_cs0_n) - // - if (eim_cs0_n == 1'b1) eim_wait_reg <= 1'b0; // clear wait - else begin - // - if (eim_fsm_state == EIM_FSM_STATE_WRITE_START) eim_wait_reg <= 1'b1; // start waiting for write to complete - if (eim_fsm_state == EIM_FSM_STATE_READ_START) eim_wait_reg <= 1'b1; // start waiting for read to complete - // - if (eim_fsm_state == EIM_FSM_STATE_WRITE_DONE) eim_wait_reg <= 1'b0; // write transaction done - if (eim_fsm_state == EIM_FSM_STATE_READ_READY) eim_wait_reg <= 1'b0; // read transaction done - // - if (eim_fsm_state == EIM_FSM_STATE_INIT) eim_wait_reg <= 1'b0; // fsm is idle, no need to wait any more - // - end - - assign eim_wait_n = ~eim_wait_reg; - - - /* These flags are used to generate 1-cycle pulses to trigger CDC transaction. - * Note that FSM goes from WRITE_LSB to WRITE_MSB and from READ_START to READ_WAIT - * unconditionally, so these flags will always be active for 1 cycle only, which - * is exactly what we need. - */ - - wire arbiter_write_req_pulse = (eim_fsm_state == EIM_FSM_STATE_WRITE_LSB) ? 1'b1 : 1'b0; - wire arbiter_read_req_pulse = (eim_fsm_state == EIM_FSM_STATE_READ_START) ? 1'b1 : 1'b0; - - // - // CDC Block - // - - /* This block is used to transfer request data from BCLK clock domain to SYS_CLK clock domain and - * then transfer acknowledge from SYS_CLK to BCLK clock domain in return. Af first 1+1+14+32 = 48 bits - * are transfered, these are: write flag, read flag, address, write data. During read transaction - * some bogus write data is passed, which is not used later anyway. During read requests 32 bits of data - * are returned, during write requests 32 bits of bogus data are returned, that are never used later. - */ - - eim_arbiter_cdc eim_cdc - ( - .eim_clk (eim_bclk), - - .eim_req (arbiter_write_req_pulse | arbiter_read_req_pulse), - .eim_ack (eim_user_ack), - - .eim_din ({arbiter_write_req_pulse, arbiter_read_req_pulse, eim_addr_latch, da_ro, eim_write_lsb_latch}), - .eim_dout (eim_user_data), - - .sys_clk (sys_clk), - .sys_addr (sys_addr), - .sys_wren (sys_wren), - .sys_data_out (sys_data_out), - .sys_rden (sys_rden), - .sys_data_in (sys_data_in) - ); - - -endmodule + input wire eim_oe_n; // | + output wire eim_wait_n; // | + + input wire sys_clk; // system clock + + output wire [13: 0] sys_addr; // | user bus + output wire sys_wren; // | + output wire [31: 0] sys_data_out; // | + output wire sys_rden; // | + input wire [31: 0] sys_data_in; // | + + + // + // Data/Address PHY + // + + /* PHY is needed to control bi-directional address/data bus. */ + + wire [15: 0] da_ro; // value read from pins + reg [15: 0] da_di; // value drives onto pins + + eim_da_phy da_phy + ( + .buf_io (eim_da), // <-- connect directly top-level port + .buf_di (da_di), + .buf_ro (da_ro), + .buf_t (eim_oe_n) // <-- driven by EIM directly + ); + + + // + // FSM + // + localparam EIM_FSM_STATE_INIT = 5'b0_0_000; // arbiter is idle + + localparam EIM_FSM_STATE_WRITE_START = 5'b1_1_000; // got address to write at + localparam EIM_FSM_STATE_WRITE_LSB = 5'b1_1_001; // got lower 16 bits of data to write + localparam EIM_FSM_STATE_WRITE_MSB = 5'b1_1_010; // got upper 16 bits of data to write + localparam EIM_FSM_STATE_WRITE_WAIT = 5'b1_1_100; // request to user-side logic sent + localparam EIM_FSM_STATE_WRITE_DONE = 5'b1_1_111; // user-side logic acknowledged transaction + + localparam EIM_FSM_STATE_READ_START = 5'b1_0_000; // got address to read from + localparam EIM_FSM_STATE_READ_WAIT = 5'b1_0_100; // request to user-side logic sent + localparam EIM_FSM_STATE_READ_READY = 5'b1_0_011; // got acknowledge from user logic + localparam EIM_FSM_STATE_READ_LSB = 5'b1_0_001; // returned lower 16 bits to master + localparam EIM_FSM_STATE_READ_MSB = 5'b1_0_010; // returned upper 16 bits to master + localparam EIM_FSM_STATE_READ_DONE = 5'b1_0_111; // transaction complete + + reg [ 4: 0] eim_fsm_state = EIM_FSM_STATE_INIT; // fsm state + reg [13: 0] eim_addr_latch = {14{1'bX}}; // transaction address + reg [15: 0] eim_write_lsb_latch = {16{1'bX}}; // lower 16 bits of data to write + + /* These flags are used to wake up from INIT state. */ + wire eim_write_start_flag = (eim_lba_n == 1'b0) && (eim_wr_n == 1'b0) && (da_ro[1:0] == 2'b00); + wire eim_read_start_flag = (eim_lba_n == 1'b0) && (eim_wr_n == 1'b1) && (da_ro[1:0] == 2'b00); + + /* These are transaction response flag and data from user-side logic. */ + wire eim_user_ack; + wire [31: 0] eim_user_data; + + /* FSM is reset whenever Chip Select is de-asserted. */ + + // + // FSM Transition Logic + // + always @(posedge eim_bclk or posedge eim_cs0_n) begin + // + if (eim_cs0_n == 1'b1) eim_fsm_state <= EIM_FSM_STATE_INIT; + // + else begin + // + case (eim_fsm_state) + // + // INIT -> WRITE, INIT -> READ + // + EIM_FSM_STATE_INIT: begin + if (eim_write_start_flag) eim_fsm_state <= EIM_FSM_STATE_WRITE_START; + if (eim_read_start_flag) eim_fsm_state <= EIM_FSM_STATE_READ_START; + end + // + // WRITE + // + EIM_FSM_STATE_WRITE_START: eim_fsm_state <= EIM_FSM_STATE_WRITE_LSB; + // + EIM_FSM_STATE_WRITE_LSB: eim_fsm_state <= EIM_FSM_STATE_WRITE_MSB; + // + EIM_FSM_STATE_WRITE_MSB: eim_fsm_state <= EIM_FSM_STATE_WRITE_WAIT; + // + EIM_FSM_STATE_WRITE_WAIT: + if (eim_user_ack) eim_fsm_state <= EIM_FSM_STATE_WRITE_DONE; + // + EIM_FSM_STATE_WRITE_DONE: eim_fsm_state <= EIM_FSM_STATE_INIT; + // + // READ + // + EIM_FSM_STATE_READ_START: eim_fsm_state <= EIM_FSM_STATE_READ_WAIT; + // + EIM_FSM_STATE_READ_WAIT: + if (eim_user_ack) eim_fsm_state <= EIM_FSM_STATE_READ_READY; + // + EIM_FSM_STATE_READ_READY: eim_fsm_state <= EIM_FSM_STATE_READ_LSB; + // + EIM_FSM_STATE_READ_LSB: eim_fsm_state <= EIM_FSM_STATE_READ_MSB; + // + EIM_FSM_STATE_READ_MSB: eim_fsm_state <= EIM_FSM_STATE_READ_DONE; + // + EIM_FSM_STATE_READ_DONE: eim_fsm_state <= EIM_FSM_STATE_INIT; + // + // + // + default: eim_fsm_state <= EIM_FSM_STATE_INIT; + // + endcase + // + end + // + end + + + // + // Address Latch + // + always @(posedge eim_bclk) + // + if ((eim_fsm_state == EIM_FSM_STATE_INIT) && (eim_write_start_flag || eim_read_start_flag)) + eim_addr_latch <= da_ro[15:2]; + + + // + // Additional Write Logic + // + always @(posedge eim_bclk) + // + if (eim_fsm_state == EIM_FSM_STATE_WRITE_START) + eim_write_lsb_latch <= da_ro; + + + // + // Additional Read Logic + // + + /* Note that this stuff operates on falling clock edge, because the cpu + * samples our bi-directional data bus on rising clock edge. + */ + + always @(negedge eim_bclk or posedge eim_cs0_n) + // + if (eim_cs0_n == 1'b1) da_di <= {16{1'bX}}; // don't care what to drive + else begin + // + if (eim_fsm_state == EIM_FSM_STATE_READ_LSB) da_di <= eim_user_data[15: 0]; // drive lower 16 bits at first... + if (eim_fsm_state == EIM_FSM_STATE_READ_MSB) da_di <= eim_user_data[31:16]; // ...then drive upper 16 bits + // + end + + + // + // Wait Logic + // + + /* Note that this stuff operates on falling clock edge, because the cpu + * samples our WAIT_N flag on rising clock edge. + */ + + reg eim_wait_reg = 1'b0; + + always @(negedge eim_bclk or posedge eim_cs0_n) + // + if (eim_cs0_n == 1'b1) eim_wait_reg <= 1'b0; // clear wait + else begin + // + if (eim_fsm_state == EIM_FSM_STATE_WRITE_START) eim_wait_reg <= 1'b1; // start waiting for write to complete + if (eim_fsm_state == EIM_FSM_STATE_READ_START) eim_wait_reg <= 1'b1; // start waiting for read to complete + // + if (eim_fsm_state == EIM_FSM_STATE_WRITE_DONE) eim_wait_reg <= 1'b0; // write transaction done + if (eim_fsm_state == EIM_FSM_STATE_READ_READY) eim_wait_reg <= 1'b0; // read transaction done + // + if (eim_fsm_state == EIM_FSM_STATE_INIT) eim_wait_reg <= 1'b0; // fsm is idle, no need to wait any more + // + end + + assign eim_wait_n = ~eim_wait_reg; + + + /* These flags are used to generate 1-cycle pulses to trigger CDC transaction. + * Note that FSM goes from WRITE_LSB to WRITE_MSB and from READ_START to READ_WAIT + * unconditionally, so these flags will always be active for 1 cycle only, which + * is exactly what we need. + */ + + wire arbiter_write_req_pulse = (eim_fsm_state == EIM_FSM_STATE_WRITE_LSB) ? 1'b1 : 1'b0; + wire arbiter_read_req_pulse = (eim_fsm_state == EIM_FSM_STATE_READ_START) ? 1'b1 : 1'b0; + + // + // CDC Block + // + + /* This block is used to transfer request data from BCLK clock domain to SYS_CLK clock domain and + * then transfer acknowledge from SYS_CLK to BCLK clock domain in return. Af first 1+1+14+32 = 48 bits + * are transfered, these are: write flag, read flag, address, write data. During read transaction + * some bogus write data is passed, which is not used later anyway. During read requests 32 bits of data + * are returned, during write requests 32 bits of bogus data are returned, that are never used later. + */ + + eim_arbiter_cdc eim_cdc + ( + .eim_clk (eim_bclk), + + .eim_req (arbiter_write_req_pulse | arbiter_read_req_pulse), + .eim_ack (eim_user_ack), + + .eim_din ({arbiter_write_req_pulse, arbiter_read_req_pulse, eim_addr_latch, da_ro, eim_write_lsb_latch}), + .eim_dout (eim_user_data), + + .sys_clk (sys_clk), + .sys_addr (sys_addr), + .sys_wren (sys_wren), + .sys_data_out (sys_data_out), + .sys_rden (sys_rden), + .sys_data_in (sys_data_in) + ); + + +endmodule diff --git a/rtl/src/verilog/eim_da_phy.v b/rtl/src/verilog/eim_da_phy.v index 9fe0c3b..9b76d3b 100644 --- a/rtl/src/verilog/eim_da_phy.v +++ b/rtl/src/verilog/eim_da_phy.v @@ -1,47 +1,47 @@ -`timescale 1ns / 1ps - -module eim_da_phy - ( - buf_io, - buf_di, buf_ro, - buf_t - ); - - // - // Parameters - // - parameter BUS_WIDTH = 16; - - // - // Ports - // - inout wire [BUS_WIDTH-1:0] buf_io; // connect directly to top-level pins - input wire [BUS_WIDTH-1:0] buf_di; // drive input (value driven onto pins) - output wire [BUS_WIDTH-1:0] buf_ro; // receiver output (value read from pins) - input wire buf_t; // tristate control (driver is disabled during tristate) - - // - // IOBUFs - // +`timescale 1ns / 1ps + +module eim_da_phy + ( + buf_io, + buf_di, buf_ro, + buf_t + ); + + // + // Parameters + // + parameter BUS_WIDTH = 16; + + // + // Ports + // + inout wire [BUS_WIDTH-1:0] buf_io; // connect directly to top-level pins + input wire [BUS_WIDTH-1:0] buf_di; // drive input (value driven onto pins) + output wire [BUS_WIDTH-1:0] buf_ro; // receiver output (value read from pins) + input wire buf_t; // tristate control (driver is disabled during tristate) + + // + // IOBUFs + // genvar i; - generate for (i=0; i