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Diffstat (limited to 'src/verilog/novena_clkmgr_new.v')
| -rw-r--r-- | src/verilog/novena_clkmgr_new.v | 137 |
1 files changed, 137 insertions, 0 deletions
diff --git a/src/verilog/novena_clkmgr_new.v b/src/verilog/novena_clkmgr_new.v new file mode 100644 index 0000000..00ed195 --- /dev/null +++ b/src/verilog/novena_clkmgr_new.v @@ -0,0 +1,137 @@ +//====================================================================== +// +// novena_clkmgr_new.v +// --------------- +// Clock and reset implementation for the Cryptech Novena +// FPGA framework. +// +// +// Author: Pavel Shatov +// Copyright (c) 2015, NORDUnet A/S All rights reserved. +// +// Redistribution and use in source and binary forms, with or without +// modification, are permitted provided that the following conditions +// are met: +// - Redistributions of source code must retain the above copyright +// notice, this list of conditions and the following disclaimer. +// +// - Redistributions in binary form must reproduce the above copyright +// notice, this list of conditions and the following disclaimer in the +// documentation and/or other materials provided with the distribution. +// +// - Neither the name of the NORDUnet nor the names of its contributors may +// be used to endorse or promote products derived from this software +// without specific prior written permission. +// +// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS +// IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED +// TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A +// PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT +// HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, +// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED +// TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR +// PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF +// LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING +// NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS +// SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. +// +//====================================================================== + +module novena_clkmgr_new + ( + input wire gclk_p, // signal from clock pins + input wire gclk_n, // + + input wire reset_mcu_b, // cpu reset (async, active-low) + + output wire sys_clk, // buffered system clock output + output wire sys_rst // system reset output (sync, active-high) + ); +
+
+ //
+ // Parameters
+ //
+ parameter CLK_OUT_MUL = 2;
+ parameter CLK_OUT_DIV = 2;
+ + // + // IBUFGDS + // + (* BUFFER_TYPE="NONE" *) + wire gclk; + + IBUFGDS IBUFGDS_gclk + ( + .I(gclk_p), + .IB(gclk_n), + .O(gclk) + ); + + + // + // DCM + // + wire dcm_reset; // dcm reset + wire dcm_locked; // output clock valid + wire gclk_missing; // no input clock + + clkmgr_dcm_new #
+ (
+ .CLK_OUT_MUL (CLK_OUT_MUL),
+ .CLK_OUT_DIV (CLK_OUT_DIV)
+ )
+ dcm + ( + .clk_in (gclk), + .reset_in (dcm_reset), + .gclk_missing_out (gclk_missing), + + .clk_out (sys_clk), + .clk_valid_out (dcm_locked) + ); + + + // + // DCM Reset Logic + // + + /* DCM should be reset on power-up, when input clock is stopped or when the + * CPU gets reset. + */ + + reg [15: 0] dcm_rst_shreg = {16{1'b1}}; // 16-bit shift register + + always @(posedge gclk or negedge reset_mcu_b or posedge gclk_missing) + // + if ((reset_mcu_b == 1'b0) || (gclk_missing == 1'b1)) + dcm_rst_shreg <= {16{1'b1}}; + else + dcm_rst_shreg <= {dcm_rst_shreg[14:0], 1'b0}; + + assign dcm_reset = dcm_rst_shreg[15]; + + + // + // System Reset Logic + // + + /* System reset is asserted for 16 cycles whenever DCM aquires lock. */ + + reg [15: 0] sys_rst_shreg = {16{1'b1}}; // 16-bit shift register + + always @(posedge sys_clk or negedge reset_mcu_b or posedge gclk_missing or negedge dcm_locked) + // + if ((reset_mcu_b == 1'b0) || (gclk_missing == 1'b1) || (dcm_locked == 1'b0)) + sys_rst_shreg <= {16{1'b1}}; + else if (dcm_locked == 1'b1) + sys_rst_shreg <= {sys_rst_shreg[14:0], 1'b0}; + + assign sys_rst = sys_rst_shreg[15]; + + +endmodule + +//====================================================================== +// EOF novena_clkmgr_new.v +//====================================================================== |