Add parameter to make prescale read-only

Author: alexforencich

rtl/i2c_master_wbs_8.v

@@ -32,6 +32,7 @@ THE SOFTWARE.
 module i2c_master_wbs_8 #
 (
     parameter DEFAULT_PRESCALE = 1,
+    parameter FIXED_PRESCALE = 0,
     parameter CMD_FIFO = 1,
     parameter CMD_FIFO_ADDR_WIDTH = 5,
     parameter WRITE_FIFO = 1,
@@ -384,11 +385,15 @@ always @* begin
                 end
                 4'h6: begin
                     // prescale low
-                    prescale_next[7:0] = wbs_dat_i;
+                    if (!FIXED_PRESCALE) begin
+                        prescale_next[7:0] = wbs_dat_i;
+                    end
                 end
                 4'h7: begin
                     // prescale high
-                    prescale_next[15:8] = wbs_dat_i;
+                    if (!FIXED_PRESCALE) begin
+                        prescale_next[15:8] = wbs_dat_i;
+                    end
                 end
             endcase
             wbs_ack_o_next = ~wbs_ack_o_reg;

tb/test_i2c_master_wbs_8.py

@@ -47,6 +47,7 @@ def bench():
 
     # Parameters
     DEFAULT_PRESCALE = 1
+    FIXED_PRESCALE = 0
     CMD_FIFO = 1
     CMD_FIFO_ADDR_WIDTH = 5
     WRITE_FIFO = 1

tb/test_i2c_master_wbs_8.v

@@ -33,6 +33,7 @@ module test_i2c_master_wbs_8;
 
 // Parameters
 parameter DEFAULT_PRESCALE = 1;
+parameter FIXED_PRESCALE = 0;
 parameter CMD_FIFO = 1;
 parameter CMD_FIFO_ADDR_WIDTH = 5;
 parameter WRITE_FIFO = 1;
@@ -91,6 +92,7 @@ end
 
 i2c_master_wbs_8 #(
     .DEFAULT_PRESCALE(DEFAULT_PRESCALE),
+    .FIXED_PRESCALE(FIXED_PRESCALE),
     .CMD_FIFO(CMD_FIFO),
     .CMD_FIFO_ADDR_WIDTH(CMD_FIFO_ADDR_WIDTH),
     .WRITE_FIFO(WRITE_FIFO),