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Diffstat (limited to 'fpga/usrp2/control_lib/dcache.v')
| -rw-r--r-- | fpga/usrp2/control_lib/dcache.v | 182 |
1 files changed, 182 insertions, 0 deletions
diff --git a/fpga/usrp2/control_lib/dcache.v b/fpga/usrp2/control_lib/dcache.v new file mode 100644 index 000000000..384c5a149 --- /dev/null +++ b/fpga/usrp2/control_lib/dcache.v @@ -0,0 +1,182 @@ +// +// Copyright 2011 Ettus Research LLC +// +// This program is free software: you can redistribute it and/or modify +// it under the terms of the GNU General Public License as published by +// the Free Software Foundation, either version 3 of the License, or +// (at your option) any later version. +// +// This program 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 General Public License for more details. +// +// You should have received a copy of the GNU General Public License +// along with this program. If not, see <http://www.gnu.org/licenses/>. +// + + +module dcache + #(parameter AWIDTH=14, + parameter CWIDTH=6) + (input wb_clk_i, + input wb_rst_i, + + input [AWIDTH-1:0] dwb_adr_i, + input dwb_stb_i, + input dwb_we_i, + input [3:0] dwb_sel_i, + input [31:0] dwb_dat_i, + output [31:0] dwb_dat_o, + output dwb_ack_o, + + input [31:0] dram_dat_i, + output [31:0] dram_dat_o, + output [AWIDTH-1:0] dram_adr_o, + output dram_we_o, + output dram_en_o, + output [3:0] dram_sel_o ); + + localparam TAGWIDTH = AWIDTH-CWIDTH-2; + reg stb_d1, ack_d1, miss_d1; + reg [AWIDTH-1:0] held_addr; + reg [31:0] ddata [0:(1<<CWIDTH)-1]; + reg [TAGWIDTH-1:0] dtags [0:(1<<CWIDTH)-1]; + reg dvalid [0:(1<<CWIDTH)-1]; + + wire [CWIDTH-1:0] rd_line, wr_line; + wire [TAGWIDTH-1:0] wr_tags; + wire cache_write, invalidate; + wire [31:0] wr_data; + + // ///////////////////////////////////// + // Write into cache + integer i; + always @(posedge wb_clk_i) + if(wb_rst_i) + for(i=0;i<(1<<CWIDTH);i=i+1) + dvalid[i] <= 0; + else + if(invalidate) + dvalid[wr_line] <= 1'b0; + else if(cache_write) + dvalid[wr_line] <= 1'b1; + + always @(posedge wb_clk_i) + if(cache_write) + begin + ddata[wr_line] <= wr_data; + dtags[wr_line] <= wr_tags; + end + + // ////////////////////////////////////// + // Read from Cache + wire [TAGWIDTH-1:0] tag_out = dtags[rd_line]; + wire valid_out = dvalid[rd_line]; + wire [31:0] data_out = ddata[rd_line]; + wire cache_hit = valid_out & (tag_out == dwb_adr_i[AWIDTH-1:CWIDTH+2]); + wire cache_miss = ~cache_hit; + + // ////////////////////////////////////// + // Handle 1-cycle delay of Block-RAM + always @(posedge wb_clk_i) + if(wb_rst_i) + stb_d1 <= 0; + else + stb_d1 <= dwb_stb_i; + + always @(posedge wb_clk_i) + if(wb_rst_i) + held_addr <= 0; + else + held_addr <= dwb_adr_i; + + always @(posedge wb_clk_i) + if(wb_rst_i) + ack_d1 <= 1'b0; + else + ack_d1 <= dwb_ack_o; + + always @(posedge wb_clk_i) + if(wb_rst_i) + miss_d1 <= 0; + else + miss_d1 <= cache_miss; + +`define DC_NOCACHE +//`define DC_BASIC +//`define DC_FORWARDING_DP +//`define DC_FORWARDING_SP +//`define DC_PREFETCH + +`ifdef DC_NOCACHE + assign dwb_dat_o = dram_dat_i; + assign dwb_ack_o = dwb_stb_i & (dwb_we_i | (stb_d1 & ~ack_d1)); + assign dram_adr_o = dwb_adr_i; + assign dram_en_o = dwb_stb_i; + assign dram_dat_o = dwb_dat_i; + assign dram_we_o = dwb_we_i; + assign dram_sel_o = dwb_sel_i; + assign rd_line = 0; + assign wr_line = 0; + assign wr_tags = 0; + assign wr_data = 0; + assign cache_write = 0; + assign invalidate = 0; +`endif + +`ifdef DC_BASIC // Very basic, no forwarding, 2 wait states on miss + assign dwb_dat_o = data_out; + assign dwb_ack_o = dwb_stb_i & cache_hit; + assign dram_adr_o = dwb_adr_i; + assign dram_en_o = dwb_stb_i; + assign dram_dat_o = dwb_dat_i; + assign dram_we_o = dwb_we_i; + assign dram_sel_o = dwb_sel_i; + assign rd_line = dwb_adr_i[CWIDTH+1:2]; + assign wr_line = rd_line; + assign wr_tags = dwb_adr_i[AWIDTH-1:CWIDTH+2]; + assign wr_data = dwb_we_i ? dwb_dat_i : dram_dat_i; + assign cache_write = dwb_stb_i & (dwb_we_i | (stb_d1 & miss_d1)); + assign invalidate = dwb_we_i & ~(&dwb_sel_i); +`endif + +`ifdef DC_FORWARDING_DP // Simple forwarding, 1 wait state on miss, dual-port ram + assign dwb_dat_o = cache_hit ? data_out : dram_dat_i; + assign dwb_ack_o = dwb_stb_i & (cache_hit | (stb_d1 & ~ack_d1)); + assign dram_adr_o = dwb_adr_i; + assign dram_en_o = 1'b1; + assign dram_dat_o = dwb_dat_i; + assign dram_we_o = dwb_we_i; + assign dram_sel_o = dwb_sel_i; + assign rd_line = dwb_adr_i[CWIDTH+1:2]; + assign wr_line = held_addr[CWIDTH+1:2]; + assign wr_tags = held_addr[AWIDTH-1:CWIDTH+2]; + assign wr_data = dram_dat_i; + assign cache_write = dwb_stb_i & stb_d1 & miss_d1 & ~ack_d1; + assign invalidate = 0; +`endif + +`ifdef DC_FORWARDING_SP // Simple forwarding, 1 wait state on miss, single-port ram + assign dwb_dat_o = cache_hit ? data_out : dram_dat_i; + assign dwb_ack_o = dwb_stb_i & (cache_hit | (stb_d1 & ~ack_d1)); + assign dram_adr_o = dwb_adr_i; + assign dram_en_o = 1'b1; + assign dram_dat_o = dwb_dat_i; + assign dram_we_o = dwb_we_i; + assign dram_sel_o = dwb_sel_i; + assign rd_line = dwb_adr_i[CWIDTH+1:2]; + assign wr_line = rd_line; + assign wr_tags = dwb_adr_i[AWIDTH-1:CWIDTH+2]; + assign wr_data = dram_dat_i; + assign cache_write = dwb_stb_i & stb_d1 & miss_d1 & ~ack_d1; + assign invalidate = 0; +`endif + +`ifdef DC_PREFETCH // Forwarding plus prefetch + +`endif + + +endmodule // dcache + |