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| author | Eric Dao <eric@erickhangdao.com> | 2025-03-10 17:54:31 -0400 |
|---|---|---|
| committer | Eric Dao <eric@erickhangdao.com> | 2025-03-10 17:54:31 -0400 |
| commit | ab224e2e6ba65f5a369ec392f99cd8845ad06c98 (patch) | |
| tree | a1e757e9341863ed52b8ad4c5a1c45933aab9da4 /python/openvino/demo/ip/intel_ai_ip/verilog/dla_cdc_reset_aligned.sv | |
| parent | 40da1752f2c8639186b72f6838aa415e854d0b1d (diff) | |
| download | thesis-master.tar.gz thesis-master.tar.bz2 thesis-master.zip | |
Diffstat (limited to 'python/openvino/demo/ip/intel_ai_ip/verilog/dla_cdc_reset_aligned.sv')
| -rw-r--r-- | python/openvino/demo/ip/intel_ai_ip/verilog/dla_cdc_reset_aligned.sv | 105 |
1 files changed, 105 insertions, 0 deletions
diff --git a/python/openvino/demo/ip/intel_ai_ip/verilog/dla_cdc_reset_aligned.sv b/python/openvino/demo/ip/intel_ai_ip/verilog/dla_cdc_reset_aligned.sv new file mode 100644 index 0000000..d0d84d1 --- /dev/null +++ b/python/openvino/demo/ip/intel_ai_ip/verilog/dla_cdc_reset_aligned.sv @@ -0,0 +1,105 @@ +// Copyright 2022 Intel Corporation. +// +// This software and the related documents are Intel copyrighted materials, +// and your use of them is governed by the express license under which they +// were provided to you ("License"). Unless the License provides otherwise, +// you may not use, modify, copy, publish, distribute, disclose or transmit +// this software or the related documents without Intel's prior written +// permission. +// +// This software and the related documents are provided as is, with no express +// or implied warranties, other than those that are expressly stated in the +// License. + +`resetall +`undefineall +`default_nettype none + +/// Synchronize a reset to a clock domain. Provide both asynchronous asserting and synchronous asserting reset outputs +/// The output asynchronous reset and the synchronous reset will NOT assert at the same time. +/// Both output resets deassert synchronous to clk and on the same cycle +/// The full delay from i_async_resetn to o_sync_resetn is approximately *8 cycles* +module dla_cdc_reset_aligned #( + parameter PIPE_STAGES = 2 // Number of addition registers to add to sync (and async) reset to allow retiming on o_sync_resetn +) ( + input wire clk, + input wire i_async_resetn, + + output logic o_async_resetn, /// Reset asserts asynchronously with i_async_reset_n, deasserts synchronous to clk on the same cycle as o_sync_resetn + output logic o_sync_resetn /// Reset asserts synchronously, and deasserts synchronous to clk on the same cycle as o_async_resetn +); + +logic w_resetn; + +// We instantiate an internal module for custom constraint matching. (The aclr pin gets the -to constraint) +dla_clock_cross_half_sync_internal #( + .METASTABILITY_STAGES ( 3 ) +) dla_areset_clock_cross_sync_special_name_for_sdc_wildcard_matching ( + .i_src_data (1'b1), + + .clk_dst (clk), + .i_dst_async_resetn (i_async_resetn), + .o_dst_data (w_resetn) +); + +localparam META_STAGES = 3; + +// w_resetn still asserts asynchronously so we have to clean it again to use it in fully synchronous logic + +logic w_fully_sync_resetn; + +dla_clock_cross_half_sync #( + .METASTABILITY_STAGES ( META_STAGES ) +) fully_sync_areset ( + .i_src_data (w_resetn), + + .clk_dst (clk), + .i_dst_async_resetn (1'b1), + .o_dst_data (w_fully_sync_resetn) +); + +// Match the above half sync de-assertion latency + +logic [META_STAGES-1:0] r_async_resetn_match_half_sync; // match the pipelining for synchronous reset so that all logic exits from reset on the same clock cycle + +always_ff @(posedge clk or negedge w_resetn) begin + if (w_resetn == 1'b0) begin + r_async_resetn_match_half_sync <= {META_STAGES{1'b0}}; + end else begin + r_async_resetn_match_half_sync <= {r_async_resetn_match_half_sync[META_STAGES-2:0], 1'b1}; + end +end + +if (PIPE_STAGES == 0) begin + assign o_async_resetn = r_async_resetn_match_half_sync[META_STAGES-1]; + assign o_sync_resetn = w_fully_sync_resetn; +end else begin + // Add a small pipeline to synchronous reset to allow retiming on these flops + + // No constraints are needed on r_resetn_sync_pipe because w_fully_sync_resetn is already synchronized. + logic [PIPE_STAGES-1:0] r_resetn_sync_pipe; // pipelining added to reset which will be consumed synchronously, retiming should still be allowed on that logic + + // reset pipelining on synchronous reset + always_ff @(posedge clk) begin //no reset + r_resetn_sync_pipe <= {r_resetn_sync_pipe[PIPE_STAGES-2:0], w_fully_sync_resetn}; + end + + // Again, match the above latency + logic [PIPE_STAGES-1:0] r_async_resetn_match_sync_pipe; // match the pipelining for synchronous reset so that all logic exits from reset on the same clock cycle + + always_ff @(posedge clk or negedge w_resetn) begin + if (w_resetn == 1'b0) begin + r_async_resetn_match_sync_pipe <= {PIPE_STAGES{1'b0}}; + end else begin + r_async_resetn_match_sync_pipe <= {r_async_resetn_match_sync_pipe[PIPE_STAGES-2:0], r_async_resetn_match_half_sync[META_STAGES-1]}; + end + end + + // for registers that consume reset _asynchronous assertion_ with synchronous deassert + assign o_async_resetn = r_async_resetn_match_sync_pipe [PIPE_STAGES-1]; + + // for registers that can take synchronous asserting reset. r_resetn_sync_pipe can be replicated and retimed by synthesis safely + assign o_sync_resetn = r_resetn_sync_pipe [PIPE_STAGES-1]; +end + +endmodule |
