From 4876225f60258a9bf467e606812c5763fec3739b Mon Sep 17 00:00:00 2001
From: liangkangnan <liangkangnan@163.com>
Date: Wed, 23 Sep 2020 21:39:20 +0800
Subject: [PATCH] rtl: utils: add full handshake CDC source

Signed-off-by: liangkangnan <liangkangnan@163.com>
---
 rtl/utils/full_handshake_rx.v | 128 +++++++++++++++++++++++++++++
 rtl/utils/full_handshake_tx.v | 147 ++++++++++++++++++++++++++++++++++
 sim/sim_default_nowave.bat    |   2 +-
 sim/sim_new_nowave.bat        |   2 +-
 4 files changed, 277 insertions(+), 2 deletions(-)
 create mode 100644 rtl/utils/full_handshake_rx.v
 create mode 100644 rtl/utils/full_handshake_tx.v

diff --git a/rtl/utils/full_handshake_rx.v b/rtl/utils/full_handshake_rx.v
new file mode 100644
index 0000000..67f86ec
--- /dev/null
+++ b/rtl/utils/full_handshake_rx.v
@@ -0,0 +1,128 @@
+ /*                                                                      
+ Copyright 2020 Blue Liang, liangkangnan@163.com
+                                                                         
+ Licensed under the Apache License, Version 2.0 (the "License");         
+ you may not use this file except in compliance with the License.        
+ You may obtain a copy of the License at                                 
+                                                                         
+     http://www.apache.org/licenses/LICENSE-2.0                          
+                                                                         
+ Unless required by applicable law or agreed to in writing, software    
+ distributed under the License is distributed on an "AS IS" BASIS,       
+ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ See the License for the specific language governing permissions and     
+ limitations under the License.                                          
+ */
+
+// 数据接收端模块
+// 跨时钟域传输，全(四次)握手协议
+// req = 1
+// ack_o = 1
+// req = 0
+// ack_o = 0
+module full_handshake_rx #(
+    parameter DW = 32)(             // RX要接收数据的位宽
+
+    input wire clk,                 // RX端时钟信号
+    input wire rst_n,               // RX端复位信号
+
+    // from tx
+    input wire req_i,               // TX端请求信号
+    input wire[DW-1:0] req_data_i,  // TX端输入数据
+
+    // to tx
+    output wire ack_o,              // RX端应答TX端信号
+
+    // to rx
+    output wire[DW-1:0] recv_data_o,// RX端接收到的数据
+    output wire recv_rdy_o          // RX端是否接收到数据信号
+
+    );
+
+    localparam STATE_IDLE     = 2'b01;
+    localparam STATE_DEASSERT = 2'b10;
+
+    reg[1:0] state;
+    reg[1:0] state_next;
+
+    always @ (posedge clk or negedge rst_n) begin
+        if (!rst_n) begin
+            state <= STATE_IDLE;
+        end else begin
+            state <= state_next;
+        end
+    end
+
+    always @ (*) begin
+        case (state)
+            // 等待TX请求信号req=1
+            STATE_IDLE: begin
+                if (req == 1'b1) begin
+                    state_next = STATE_DEASSERT;
+                end else begin
+                    state_next = STATE_IDLE;
+                end
+            end
+            // 等待req=0
+            STATE_DEASSERT: begin
+                if (req) begin
+                    state_next = STATE_DEASSERT;
+                end else begin
+                    state_next = STATE_IDLE;
+                end
+            end
+            default: begin
+                state_next = STATE_IDLE;
+            end
+        endcase
+    end
+
+    reg req_d;
+    reg req;
+
+    // 将请求信号打两拍进行同步
+    always @ (posedge clk or negedge rst_n) begin
+        if (!rst_n) begin
+            req_d <= 1'b0;
+            req <= 1'b0;
+        end else begin
+            req_d <= req_i;
+            req <= req_d;
+        end
+    end
+
+    reg[DW-1:0] recv_data;
+    reg recv_rdy;
+    reg ack;
+
+    always @ (posedge clk or negedge rst_n) begin
+        if (!rst_n) begin
+            ack <= 1'b0;
+            recv_rdy <= 1'b0;
+            recv_data <= {(DW){1'b0}};
+        end else begin
+            case (state)
+                STATE_IDLE: begin
+                    if (req == 1'b1) begin
+                        ack <= 1'b1;
+                        recv_rdy <= 1'b1;           // 这个信号只会持续一个时钟
+                        recv_data <= req_data_i;    // 这个信号只会持续一个时钟
+                    end
+                end
+                STATE_DEASSERT: begin
+                    recv_rdy <= 1'b0;
+                    recv_data <= {(DW){1'b0}};
+                    // req撤销后ack也撤销
+                    if (req == 1'b0) begin
+                        ack <= 1'b0;
+                    end
+                end
+            endcase
+        end
+    end
+
+    assign ack_o = ack;
+    assign recv_rdy_o = recv_rdy;
+    assign recv_data_o = recv_data;
+
+endmodule
diff --git a/rtl/utils/full_handshake_tx.v b/rtl/utils/full_handshake_tx.v
new file mode 100644
index 0000000..b4a2c14
--- /dev/null
+++ b/rtl/utils/full_handshake_tx.v
@@ -0,0 +1,147 @@
+ /*                                                                      
+ Copyright 2020 Blue Liang, liangkangnan@163.com
+                                                                         
+ Licensed under the Apache License, Version 2.0 (the "License");         
+ you may not use this file except in compliance with the License.        
+ You may obtain a copy of the License at                                 
+                                                                         
+     http://www.apache.org/licenses/LICENSE-2.0                          
+                                                                         
+ Unless required by applicable law or agreed to in writing, software    
+ distributed under the License is distributed on an "AS IS" BASIS,       
+ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ See the License for the specific language governing permissions and     
+ limitations under the License.                                          
+ */
+
+// 数据发送端模块
+// 跨时钟域传输，全(四次)握手协议
+// req_o = 1
+// ack = 1
+// req_o = 0
+// ack = 0
+module full_handshake_tx #(
+    parameter DW = 32)(             // TX要发送数据的位宽
+
+    input wire clk,                 // TX端时钟信号
+    input wire rst_n,               // TX端复位信号
+
+    // from rx
+    input wire ack_i,               // RX端应答信号
+
+    // from tx
+    input wire req_i,               // TX端请求信号，只需持续一个时钟
+    input wire[DW-1:0] req_data_i,  // TX端要发送的数据，只需持续一个时钟
+
+    // to tx
+    output wire idle_o,             // TX端是否空闲信号，空闲才能发数据
+
+    // to rx
+    output wire req_o,              // TX端请求信号
+    output wire[DW-1:0] req_data_o  // TX端要发送的数据
+
+    );
+
+    localparam STATE_IDLE     = 3'b001;
+    localparam STATE_ASSERT   = 3'b010;
+    localparam STATE_DEASSERT = 3'b100;
+
+    reg[2:0] state;
+    reg[2:0] state_next;
+
+    always @ (posedge clk or negedge rst_n) begin
+        if (!rst_n) begin
+            state <= STATE_IDLE;
+        end else begin
+            state <= state_next;
+        end
+    end
+
+    always @ (*) begin
+        case (state)
+            STATE_IDLE: begin
+                if (req_i == 1'b1) begin
+                    state_next = STATE_ASSERT;
+                end else begin
+                    state_next = STATE_IDLE;
+                end
+            end
+            // 等待ack=1
+            STATE_ASSERT: begin
+                if (!ack) begin
+                    state_next = STATE_ASSERT;
+                end else begin
+                    state_next = STATE_DEASSERT;
+                end
+            end
+            // 等待ack=0
+            STATE_DEASSERT: begin
+                if (!ack) begin
+                    state_next = STATE_IDLE;
+                end else begin
+                    state_next = STATE_DEASSERT;
+                end
+            end
+            default: begin
+                state_next = STATE_IDLE;
+            end
+        endcase
+    end
+
+    reg ack_d;
+    reg ack;
+
+    // 将应答信号打两拍进行同步
+    always @ (posedge clk or negedge rst_n) begin
+        if (!rst_n) begin
+            ack_d <= 1'b0;
+            ack <= 1'b0;
+        end else begin
+            ack_d <= ack_i;
+            ack <= ack_d;
+        end
+    end
+
+    reg req;
+    reg[DW-1:0] req_data;
+    reg idle;
+
+    always @ (posedge clk or negedge rst_n) begin
+        if (!rst_n) begin
+            idle <= 1'b1;
+            req <= 1'b0;
+            req_data <= {(DW){1'b0}};
+        end else begin
+            case (state)
+                // 锁存TX请求数据，在收到ack之前一直保持有效
+                STATE_IDLE: begin
+                    if (req_i == 1'b1) begin
+                        idle <= 1'b0;
+                        req <= req_i;
+                        req_data <= req_data_i;
+                    end else begin
+                        idle <= 1'b1;
+                        req <= 1'b0;
+                    end
+                end
+                // 收到RX的ack之后撤销TX请求
+                STATE_ASSERT: begin
+                    if (ack == 1'b1) begin
+                        req <= 1'b0;
+                        req_data <= {(DW){1'b0}};
+                    end
+                end
+                STATE_DEASSERT: begin
+                    if (!ack) begin
+                        idle <= 1'b1;
+                    end
+                end
+            endcase
+        end
+    end
+
+    assign idle_o = idle;
+    assign req_o = req;
+    assign req_data_o = req_data;
+
+endmodule
diff --git a/sim/sim_default_nowave.bat b/sim/sim_default_nowave.bat
index 78530f9..6407954 100644
--- a/sim/sim_default_nowave.bat
+++ b/sim/sim_default_nowave.bat
@@ -1,2 +1,2 @@
-iverilog -o out.vvp -I ..\rtl\core ..\tb\tinyriscv_soc_tb.v ..\rtl\core\defines.v ..\rtl\core\ex.v ..\rtl\core\id.v ..\rtl\core\tinyriscv.v ..\rtl\core\pc_reg.v ..\rtl\core\id_ex.v ..\rtl\core\ctrl.v ..\rtl\core\regs.v ..\rtl\perips\ram.v ..\rtl\perips\rom.v ..\rtl\perips\spi.v ..\rtl\core\if_id.v ..\rtl\core\div.v ..\rtl\core\rib.v ..\rtl\core\clint.v ..\rtl\core\csr_reg.v ..\rtl\debug\jtag_dm.v ..\rtl\debug\jtag_driver.v ..\rtl\debug\jtag_top.v ..\rtl\debug\uart_debug.v ..\rtl\perips\timer.v ..\rtl\perips\uart.v ..\rtl\perips\gpio.v ..\rtl\utils\gen_dff.v ..\rtl\utils\gen_buf.v ..\rtl\soc\tinyriscv_soc_top.v
+iverilog -o out.vvp -I ..\rtl\core ..\tb\tinyriscv_soc_tb.v ..\rtl\core\defines.v ..\rtl\core\ex.v ..\rtl\core\id.v ..\rtl\core\tinyriscv.v ..\rtl\core\pc_reg.v ..\rtl\core\id_ex.v ..\rtl\core\ctrl.v ..\rtl\core\regs.v ..\rtl\perips\ram.v ..\rtl\perips\rom.v ..\rtl\perips\spi.v ..\rtl\core\if_id.v ..\rtl\core\div.v ..\rtl\core\rib.v ..\rtl\core\clint.v ..\rtl\core\csr_reg.v ..\rtl\debug\jtag_dm.v ..\rtl\debug\jtag_driver.v ..\rtl\debug\jtag_top.v ..\rtl\debug\uart_debug.v ..\rtl\perips\timer.v ..\rtl\perips\uart.v ..\rtl\perips\gpio.v ..\rtl\utils\gen_dff.v ..\rtl\utils\gen_buf.v ..\rtl\utils\full_handshake_rx.v ..\rtl\utils\full_handshake_tx.v ..\rtl\soc\tinyriscv_soc_top.v
 vvp out.vvp
diff --git a/sim/sim_new_nowave.bat b/sim/sim_new_nowave.bat
index 7b9cf2c..23c562b 100644
--- a/sim/sim_new_nowave.bat
+++ b/sim/sim_new_nowave.bat
@@ -1,3 +1,3 @@
 ..\tools\BinToMem_CLI.exe %1 %2
-iverilog -o out.vvp -I ..\rtl\core ..\tb\tinyriscv_soc_tb.v ..\rtl\core\defines.v ..\rtl\core\ex.v ..\rtl\core\id.v ..\rtl\core\tinyriscv.v ..\rtl\core\pc_reg.v ..\rtl\core\id_ex.v ..\rtl\core\ctrl.v ..\rtl\core\regs.v ..\rtl\perips\ram.v ..\rtl\perips\rom.v ..\rtl\perips\spi.v ..\rtl\core\if_id.v ..\rtl\core\div.v ..\rtl\core\rib.v ..\rtl\core\clint.v ..\rtl\core\csr_reg.v ..\rtl\debug\jtag_dm.v ..\rtl\debug\jtag_driver.v ..\rtl\debug\jtag_top.v ..\rtl\debug\uart_debug.v ..\rtl\perips\timer.v ..\rtl\perips\uart.v ..\rtl\perips\gpio.v ..\rtl\utils\gen_dff.v ..\rtl\utils\gen_buf.v ..\rtl\soc\tinyriscv_soc_top.v
+iverilog -o out.vvp -I ..\rtl\core ..\tb\tinyriscv_soc_tb.v ..\rtl\core\defines.v ..\rtl\core\ex.v ..\rtl\core\id.v ..\rtl\core\tinyriscv.v ..\rtl\core\pc_reg.v ..\rtl\core\id_ex.v ..\rtl\core\ctrl.v ..\rtl\core\regs.v ..\rtl\perips\ram.v ..\rtl\perips\rom.v ..\rtl\perips\spi.v ..\rtl\core\if_id.v ..\rtl\core\div.v ..\rtl\core\rib.v ..\rtl\core\clint.v ..\rtl\core\csr_reg.v ..\rtl\debug\jtag_dm.v ..\rtl\debug\jtag_driver.v ..\rtl\debug\jtag_top.v ..\rtl\debug\uart_debug.v ..\rtl\perips\timer.v ..\rtl\perips\uart.v ..\rtl\perips\gpio.v ..\rtl\utils\gen_dff.v ..\rtl\utils\gen_buf.v ..\rtl\utils\full_handshake_rx.v ..\rtl\utils\full_handshake_tx.v ..\rtl\soc\tinyriscv_soc_top.v
 vvp out.vvp