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/*
 *
 * Clock, reset generation unit
 * 
 * Implements clock generation according to design defines
 * 
 */
//////////////////////////////////////////////////////////////////////
////                                                              ////
//// Copyright (C) 2009, 2010 Authors and OPENCORES.ORG           ////
////                                                              ////
//// This source file may be used and distributed without         ////
//// restriction provided that this copyright statement is not    ////
//// removed from the file and that any derivative work contains  ////
//// the original copyright notice and the associated disclaimer. ////
////                                                              ////
//// This source file is free software; you can redistribute it   ////
//// and/or modify it under the terms of the GNU Lesser General   ////
//// Public License as published by the Free Software Foundation; ////
//// either version 2.1 of the License, or (at your option) any   ////
//// later version.                                               ////
////                                                              ////
//// This source is distributed in the hope that it will be       ////
//// useful, but WITHOUT ANY WARRANTY; without even the implied   ////
//// warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR      ////
//// PURPOSE.  See the GNU Lesser General Public License for more ////
//// details.                                                     ////
////                                                              ////
//// You should have received a copy of the GNU Lesser General    ////
//// Public License along with this source; if not, download it   ////
//// from http://www.opencores.org/lgpl.shtml                     ////
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//////////////////////////////////////////////////////////////////////
 
`include "timescale.v"
`include "orpsoc-defines.v"
`include "synthesis-defines.v"
 
module clkgen
  (
   // Main clocks in, depending on board
   sys_clk_pad_i,
 
   // Wishbone clock and reset out  
   wb_clk_o,
   wb_rst_o,
 
   // JTAG clock
`ifdef JTAG_DEBUG
   tck_pad_i,
   dbg_tck_o,
`endif      
   // Main memory clocks
`ifdef VERSATILE_SDRAM
   sdram_clk_o,
   sdram_rst_o,
`endif
   // Peripheral clocks
`ifdef ETH_CLK
   eth_clk_pad_i,
   eth_clk_o,
   eth_rst_o,
 `endif
 
`ifdef USB_CLK
   usb_clk_o,
`endif
 
   // Asynchronous, active low reset in
   rst_n_pad_i
 
   );
 
   input sys_clk_pad_i;
 
   output wb_rst_o;
   output wb_clk_o;
 
`ifdef JTAG_DEBUG
   input  tck_pad_i;
   output dbg_tck_o;
`endif      
 
`ifdef VERSATILE_SDRAM
   output sdram_clk_o;
   output sdram_rst_o;
`endif
 
`ifdef ETH_CLK
   input  eth_clk_pad_i;
   output eth_clk_o;
   output eth_rst_o;
`endif
 
`ifdef USB_CLK
   output usb_clk_o;
`endif
 
   // Asynchronous, active low reset (pushbutton, typically)
   input  rst_n_pad_i;
 
   // First, deal with the asychronous reset
   wire   async_rst;
   wire   async_rst_n;
 
   assign async_rst_n  = rst_n_pad_i;
 
   // Everyone likes active-high reset signals...
   assign async_rst = ~async_rst_n;
 
 
`ifdef JTAG_DEBUG
   assign  dbg_tck_o = tck_pad_i;
`endif
 
   //
   // Declare synchronous reset wires here
   //
 
   // An active-low synchronous reset signal (usually a PLL lock signal)
   wire   sync_rst_n;
 
   // An active-low synchronous reset from ethernet PLL
   wire   sync_eth_rst_n;
 
 
`ifdef ACTEL_PLL
 `ifdef SYNTHESIS
   wire   pll_lock;   
   wire   eth_pll_lock;
 
  `ifdef PLL_XTAL64_WB36
   pll_xtal64_wb36
  `endif
  `ifdef PLL_XTAL64_WB32
   pll_xtal64_wb32
  `endif
  `ifdef PLL_XTAL64_WB30
   pll_xtal64_wb30
  `endif               
  `ifdef PLL_XTAL64_WB24
   pll_xtal64_wb24
  `endif          
  `ifdef PLL_XTAL64_WB20
   pll_xtal64_wb20
  `endif     
  `ifdef PLL_XTAL64_WB18
   pll_xtal64_wb18
  `endif
  `ifdef PLL_XTAL64_WB16
   pll_xtal64_wb16
  `endif
  `ifdef PLL_XTAL25_WB24
   pll_xtal25_wb24
  `endif
  `ifdef PLL_XTAL25_WB20
   pll_xtal25_wb20
  `endif
 
     pll0
     (
      .POWERDOWN(1'b1),
      .CLKA(sys_clk_pad_i),
      .LOCK(pll_lock),
 
  `ifdef VERSATILE_SDRAM      
      .GLA(sdram_clk_o),
  `else
      .GLA(),
  `endif      
 
      .GLB(wb_clk_o),
 
  `ifdef USB_CLK
      .GLC(usb_clk_o)
  `else
      .GLC()
  `endif      
      );
 
   assign sync_rst_n = pll_lock;
 
  `ifdef ETH_CLK   
   `ifdef ETH_CLK_PLL
 
   eth_pll eth_pll0
     (
      .POWERDOWN(1'b1),
      .CLKA(eth_clk_pad_i),
      .LOCK(eth_pll_lock),
      .GLA(eth_clk_o)
      );
   `else
   // Just instantiate global buffer for incoming ethernet clock
   gbuf eth_clk_gbuf
     (
      .CLK(eth_clk_pad_i),
      .GL(eth_clk_o)
      );
   assign eth_pll_lock = 1'b1;
   `endif // !`ifdef ETH_CLK_PLL
  `endif
 
   assign sync_eth_rst_n = eth_pll_lock;
 
 `else // !`ifdef SYNTHESIS
   // Buggy looking Actel PLL simulation model  (it was drifting when 
   // generating certain frequencies) so we will generate our own during 
   // simulation.
 
   reg 	  wb_clk_gen = 0;
   reg 	  usb_clk_gen = 0;
 
   // Delay on Actel PLLs for SDRAM clock (GLA) is 0.200ns
   parameter Tskew_actel_pll_gla = 0.200;
   assign #Tskew_actel_pll_gla sdram_clk_o  = sys_clk_pad_i;
 
   always
     #((`ACTEL_PLL_CLKB_PERIOD)/2) wb_clk_gen <=  async_rst ? 0 : ~wb_clk_gen;
 
   always
     #((`ACTEL_PLL_CLKC_PERIOD)/2) usb_clk_gen <=  async_rst ? 0 : ~usb_clk_gen;
 
   assign wb_clk_o = wb_clk_gen;
 
  `ifdef USB_CLK
   assign usb_clk_o = usb_clk_gen;   
  `endif
 
  `ifdef ETH_CLK
   `ifdef ETH_CLK_PLL
   // Ethernet clock is 125MHz on ORSoC dev board 
   // PLL set to -0.06ns delay model this here
 
   wire   eth_clk, eth_clk_dly1, eth_clk_dly2;
   assign #3.5 eth_clk_dly1 = eth_clk_pad_i;
   assign #3.5 eth_clk_dly2 = eth_clk_dly1;
   assign #(1 - 0.06)eth_clk = eth_clk_dly2;
   assign eth_clk_o = eth_clk;
   `else
 
   assign eth_clk_o = eth_clk_pad_i;
 
   `endif // !`ifdef ETH_CLK_PLL
  `endif //  `ifdef ETH_CLK
 
 
 
   reg 	  pll_lock = 0;
   reg 	  eth_pll_lock = 1;
 
   always @(async_rst)
     if (async_rst)
       pll_lock = 0;
     else
       #300 pll_lock = 1;
 
   // Assign synchronous resets
   assign sync_rst_n = pll_lock;
   assign sync_eth_rst_n = eth_pll_lock;
 
 
 `endif // !`ifdef SYNTHESIS
`endif //  `ifdef ACTEL_PLL
 
   //
   // Reset generation
   //
   //
 
 
   // Reset generation for wishbone
   reg [15:0] 	   wb_rst_shr;
   always @(posedge wb_clk_o or posedge async_rst)
     if (async_rst)
       wb_rst_shr <= 16'hffff;
     else
       wb_rst_shr <= {wb_rst_shr[14:0], ~(sync_rst_n)};
 
   assign wb_rst_o = wb_rst_shr[15];
 
 
 
`ifdef VERSATILE_SDRAM   
   // Reset generation for SDRAM controller
   reg [15:0] 	   sdram_rst_shr;
   always @(posedge sdram_clk_o or posedge async_rst)
     if (async_rst)
       sdram_rst_shr <= 16'hffff;
     else
       sdram_rst_shr <= {sdram_rst_shr[14:0], ~(sync_rst_n)};
 
   assign sdram_rst_o = sdram_rst_shr[15];
`endif //  `ifdef VERSATILE_SDRAM
 
`ifdef ETH_CLK
   // Reset generation for ethernet SMII
   reg [15:0] 	   eth_rst_shr;
   always @(posedge eth_clk_o or posedge async_rst)
     if (async_rst)
       eth_rst_shr <= 16'hffff;
     else
       eth_rst_shr <= {eth_rst_shr[14:0], ~(sync_eth_rst_n)};
 
   assign eth_rst_o = eth_rst_shr[15];
`endif //  `ifdef ETH_CLK
 
endmodule // clkgen