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[/] [openrisc/] [trunk/] [orpsocv2/] [boards/] [xilinx/] [s3adsp1800/] [rtl/] [verilog/] [clkgen/] [clkgen.v] - Rev 592
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/* * * Clock, reset generation unit for s3adsp1800 board * * 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 //// //// //// ////////////////////////////////////////////////////////////////////// `include "orpsoc-defines.v" `include "synthesis-defines.v" module clkgen ( // Main clocks in, depending on board sys_clk_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 XILINX_DDR2 clk133_o, `endif // Asynchronous, active low reset in rst_n_pad_i ); input sys_clk_i; output wb_rst_o; output wb_clk_o; `ifdef JTAG_DEBUG input tck_pad_i; output dbg_tck_o; `endif `ifdef XILINX_DDR2 output clk133_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; // Xilinx synthesis tools appear cluey enough to instantiate buffers when and // where they're needed, so we do simple assigns for this tech. 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; // IBUF for sys_clk_i wire sys_clk; IBUFG ibufg0 (.I(sys_clk_i), .O(sys_clk)); /* DCM0 wires */ wire dcm0_clk0_prebufg, dcm0_clk0; wire dcm0_clkfx_prebufg, dcm0_clkfx; wire dcm0_clkdv_prebufg, dcm0_clkdv; wire dcm0_locked; /* DCM providing main system/Wishbone clock */ DCM_SP #( .CLK_FEEDBACK("1X"), // 125 / 5 = 25 MHz .CLKDV_DIVIDE(5), // 125 * 2/8 = 31.25Mhz .CLKFX_DIVIDE(8), .CLKFX_MULTIPLY(2), // Clkin = 125 Mhz .CLKIN_PERIOD(8.000), .CLKIN_DIVIDE_BY_2("FALSE"), .CLKOUT_PHASE_SHIFT("NONE"), .DESKEW_ADJUST("SYSTEM_SYNCHRONOUS"), .DFS_FREQUENCY_MODE("LOW"), .DLL_FREQUENCY_MODE("LOW"), .DUTY_CYCLE_CORRECTION("TRUE"), .FACTORY_JF(16'hC080), .PHASE_SHIFT(0), .STARTUP_WAIT("FALSE") ) DCM_SP_INST ( .CLKFB(dcm0_clk0), .CLKIN(sys_clk), .DSSEN(1'b0), .PSCLK(1'b0), .PSEN(1'b0), .PSINCDEC(1'b0), .RST(1'b0), .CLKDV(dcm0_clkdv_prebufg), .CLKFX(dcm0_clkfx_prebufg), .CLKFX180(), .CLK0(dcm0_clk0_prebufg), .CLK2X(), .CLK2X180(), .CLK90(), .CLK180(), .CLK270(), .LOCKED(dcm0_locked), .PSDONE(), .STATUS()); BUFG dcm0_clk0_bufg (// Outputs .O (dcm0_clk0), // Inputs .I (dcm0_clk0_prebufg)); BUFG dcm0_clkfx_bufg (// Outputs .O (dcm0_clkfx), // Inputs .I (dcm0_clkfx_prebufg)); BUFG dcm0_clkdv_bufg (// Outputs .O (dcm0_clkdv), // Inputs .I (dcm0_clkdv_prebufg)); assign wb_clk_o = dcm0_clkdv; assign sync_rst_n = dcm0_locked; `ifdef XILINX_DDR2 assign clk133_o = dcm0_clk0; // 125 MHz for now `endif // // 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 XILINX_DDR2 /* // Reset generation for DDR2 controller reg [15:0] ddr2_if_rst_shr; always @(posedge ddr2_if_clk_o or posedge async_rst) if (async_rst) ddr2_if_rst_shr <= 16'hffff; else ddr2_if_rst_shr <= {ddr2_if_rst_shr[14:0], ~(sync_rst_n)}; assign ddr2_if_rst_o = ddr2_if_rst_shr[15]; */ `endif endmodule // clkgen
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