wb: replaced xwb_register_link with more performant version

9d8cbbdb · Mathias Kreider · 8cd05d79 · 9d8cbbdb · 9d8cbbdb · 9d8cbbdb
Commit 9d8cbbdb authored Apr 12, 2016 by Mathias Kreider
6 changed files
--- a/modules/wishbone/wb_crossbar/Manifest.py
+++ b/modules/wishbone/wb_crossbar/Manifest.py
@@ -3,4 +3,5 @@ files = [
  "xwb_crossbar.vhd",
  "xwb_sdb_crossbar.vhd",
  "xwb_register_link.vhd",
+  "wb_skidpad.vhd",	
  ]
--- a/modules/wishbone/wbgenplus/wb_skidpad.vhd
+++ b/modules/wishbone/wbgenplus/wb_skidpad.vhd
--- a/modules/wishbone/wb_crossbar/xwb_register_link.vhd
+++ b/modules/wishbone/wb_crossbar/xwb_register_link.vhd
@@ -6,22 +6,23 @@
 -- Author     : Wesley W. Terpstra
 -- Company    : GSI
 -- Created    : 2013-12-16
-- Last update: 2013-12-16
+-- Last update: 2016-04-12
 -- Platform   : FPGA-generic
 -- Standard   : VHDL'93
 -------------------------------------------------------------------------------
 -- Description:
 --
-- Adds a register between two wishbone interfaces.
+-- Adds registers between two wishbone interfaces.
 -- Useful to improve timing closure when placed between crossbars.
-- Be warned: it reduces the available bandwidth by a half.
 --
 -------------------------------------------------------------------------------
 -- Copyright (c) 2011 GSI / Wesley W. Terpstra
 -------------------------------------------------------------------------------
 -- Revisions  :
 -- Date        Version  Author          Description
-- 2013-12-16  1.0      wterpstra       V1
+-- 2013-12-16  1.0      wterpstra       V1, half bandwidth
+-- 2016-04-12  2.0      mkreider        reworked, now with full throughput
+
 -------------------------------------------------------------------------------


@@ -42,34 +43,56 @@ end xwb_register_link;

 architecture rtl of xwb_register_link is

-  signal r_slave  : t_wishbone_slave_out;
-  signal r_master : t_wishbone_master_out;
+  signal s_push, s_pop   : std_logic;
+  signal s_full, s_empty : std_logic;
+  signal r_ack,  r_err   : std_logic;
+  signal r_dat           : t_wishbone_data;

 begin
-
-  slave_o  <= r_slave;
-  master_o <= r_master;
  
+  sp : wb_skidpad
+  generic map(
+    g_adrbits   => c_wishbone_address_width
+  )
+  Port map(
+    clk_i        => clk_sys_i,
+    rst_n_i      => rst_n_i,
+    push_i       => s_push,
+    pop_i        => s_pop,
+    full_o       => s_full,
+    empty_o      => s_empty,
+    adr_i        => slave_i.adr,
+    dat_i        => slave_i.dat,
+    sel_i        => slave_i.sel,
+    we_i         => slave_i.we,
+    adr_o        => master_o.adr,
+    dat_o        => master_o.dat,
+    sel_o        => master_o.sel,
+    we_o         => master_o.we
+  );
+
+
+  slave_o.ack   <= r_ack;	
+  slave_o.err   <= r_err;
+  slave_o.dat   <= r_dat; 
+
+  s_pop         <= not master_i.stall;
+  s_push        <= slave_i.cyc and slave_i.stb and not s_full;
+  slave_o.stall <= s_full;
+  master_o.stb  <= not s_empty; 
+  master_o.cyc  <= slave_i.cyc;
+
  main : process(clk_sys_i, rst_n_i) is
  begin
    if rst_n_i = '0' then
-      r_slave  <= cc_dummy_slave_out;
-      r_master <= cc_dummy_master_out;
-      r_slave.stall <= '0';
+      r_ack  <= '0';
+      r_err  <= '0';
+      r_dat  <= (others => '0');  
    elsif rising_edge(clk_sys_i) then
      -- no flow control on ack/err
-      r_slave <= master_i;
-      
-      -- either we are accepting data (stb=0) or pushing data (stb=1)
-      if r_master.stb = '0' then
-        r_master      <= slave_i;
-        r_master.stb  <= slave_i.cyc and slave_i.stb;
-        r_slave.stall <= slave_i.cyc and slave_i.stb;
-      else
-        r_master.stb  <= r_master.stb and master_i.stall;
-        r_slave.stall <= r_master.stb and master_i.stall;
-      end if;
-      
+      r_ack <= master_i.ack;
+      r_err <= master_i.err;
+      r_dat <= master_i.dat;
    end if;
  end process;


--- a/modules/wishbone/wbgenplus/Manifest.py
+++ b/modules/wishbone/wbgenplus/Manifest.py
-files = ["wb_skidpad.vhd",
-         "wbgenplus_pkg.vhd",
+files = ["wbgenplus_pkg.vhd",

 ]

--- a/modules/wishbone/wbgenplus/wbgenplus_pkg.vhd
+++ b/modules/wishbone/wbgenplus/wbgenplus_pkg.vhd
@@ -4,33 +4,6 @@ use ieee.numeric_std.all;

 package wbgenplus_pkg is

-  component wb_skidpad is
-  generic(
-     g_adrbits   : natural   := 32 --Number of bits in adr
-  );
-  Port(
-     clk_i        : std_logic;
-     rst_n_i      : std_logic;             
-    
-     push_i       : in  std_logic;
-     pop_i        : in  std_logic;
-     full_o       : out std_logic;
-     empty_o      : out std_logic;  
-
-     adr_i        : in  std_logic_vector(g_adrbits-1 downto 0);
-     dat_i        : in  std_logic_vector(32-1 downto 0);
-     sel_i        : in  std_logic_vector(4-1 downto 0);  
-     we_i         : in  std_logic;
-
-     adr_o        : out std_logic_vector(g_adrbits-1 downto 0);
-     dat_o        : out std_logic_vector(32-1 downto 0);
-     sel_o        : out std_logic_vector(4-1 downto 0);  
-     we_o         : out std_logic
-   
-     
-  );
-  end component;
-
  type matrix is array(natural range <>, natural range <>) of std_logic;

  -- assign row

--- a/modules/wishbone/wishbone_pkg.vhd
+++ b/modules/wishbone/wishbone_pkg.vhd
@@ -384,6 +384,32 @@ package wishbone_pkg is
      master_o  : out t_wishbone_master_out);
  end component;

+  -- skidpad. acts like a fifo in wb flow control, but costs less
+  component wb_skidpad is
+  generic(
+     g_adrbits   : natural   := 32
+  );
+  Port(
+     clk_i        : std_logic;
+     rst_n_i      : std_logic;
+
+     push_i       : in  std_logic;
+     pop_i        : in  std_logic;
+     full_o       : out std_logic;
+     empty_o      : out std_logic;
+
+     adr_i        : in  std_logic_vector(g_adrbits-1 downto 0);
+     dat_i        : in  std_logic_vector(32-1 downto 0);
+     sel_i        : in  std_logic_vector(4-1 downto 0);
+     we_i         : in  std_logic;
+
+     adr_o        : out std_logic_vector(g_adrbits-1 downto 0);
+     dat_o        : out std_logic_vector(32-1 downto 0);
+     sel_o        : out std_logic_vector(4-1 downto 0);
+     we_o         : out std_logic
+  );
+  end component;
+
  component sdb_rom is
    generic(
      g_layout  : t_sdb_record_array;