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[/] [xulalx25soc/] [trunk/] [rtl/] [wbuexec.v] - Rev 93
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//////////////////////////////////////////////////////////////////////////////// // // Filename: wbuexec.v // // Project: XuLA2 board // // Purpose: This is the part of the USB-JTAG to wishbone conversion that // actually conducts a wishbone transaction. Transactions are // requested via codewords that come in, and the results recorded on // codewords that are sent out. Compression and/or decompression, coding // etc. all take place external to this routine. // // // Creator: Dan Gisselquist, Ph.D. // Gisselquist Technology, LLC // //////////////////////////////////////////////////////////////////////////////// // // Copyright (C) 2015, Gisselquist Technology, LLC // // This program is free software (firmware): 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 MERCHANTIBILITY or // FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License // for more details. // // License: GPL, v3, as defined and found on www.gnu.org, // http://www.gnu.org/licenses/gpl.html // // //////////////////////////////////////////////////////////////////////////////// // // `define WB_IDLE 3'b000 `define WB_READ_REQUEST 3'b001 `define WB_WRITE_REQUEST 3'b010 `define WB_ACK 3'b011 `define WB_WAIT_ON_NEXT_WRITE 3'b100 `define WB_FLUSH_WRITE_REQUESTS 3'b101 module wbuexec(i_clk, i_rst, i_stb, i_codword, o_busy, o_wb_cyc, o_wb_stb, o_wb_we, o_wb_addr, o_wb_data, i_wb_ack, i_wb_stall, i_wb_err, i_wb_data, o_stb, o_codword); input i_clk, i_rst; // The command inputs input i_stb; input [35:0] i_codword; output wire o_busy; // Wishbone outputs output wire o_wb_cyc, o_wb_stb; output reg o_wb_we; output reg [31:0] o_wb_addr, o_wb_data; // Wishbone inputs input i_wb_ack, i_wb_stall, i_wb_err; input [31:0] i_wb_data; // And our codeword outputs output reg o_stb; output reg [35:0] o_codword; wire w_accept, w_eow, w_newwr, w_new_err; // wire w_newad, w_newrd; assign w_accept = (i_stb)&&(~o_busy); // assign w_newad = (w_accept)&&(i_codword[35:34] == 2'b00); assign w_newwr = (w_accept)&&(i_codword[35:34] == 2'b01); assign w_eow = (w_accept)&&(i_codword[35:30] == 6'h2e); // assign w_newrd = (w_accept)&&(i_codword[35:34] == 2'b11); wire [31:0] w_cod_data; assign w_cod_data={ i_codword[32:31], i_codword[29:0] }; assign w_new_err = ((w_accept) &&(i_codword[35:33] != 3'h3) &&(i_codword[35:30] != 6'h2e)); reg [2:0] wb_state; reg [9:0] r_acks_needed, r_len; reg r_inc, r_new_addr, last_read_request, last_ack, zero_acks; initial r_new_addr = 1'b1; initial wb_state = `WB_IDLE; initial o_stb = 1'b0; always @(posedge i_clk) if (i_rst) begin wb_state <= `WB_IDLE; o_stb <= 1'b1; o_codword <= { 6'h3, i_wb_data[29:0] }; end else case(wb_state) `WB_IDLE: begin // Now output codewords while we're idle, // ... unless we get an address command (later). o_stb <= 1'b0; // The new instruction. The following // don't matter if we're not running, // so set them any time in this state, // and if we move then they'll still be // set right. // // Increment addresses? r_inc <= i_codword[30]; // Will this be a write? o_wb_we <= (~i_codword[35]); // // Our next codeword will be the new address (if there // is one). Set it here. The o_stb line will determine // if this codeword is actually sent out. // o_codword <= { 4'h2, o_wb_addr }; o_wb_we <= (i_codword[35:34] != 2'b11); // // The output data is a don't care, unless we are // starting a write. Hence, let's always set it as // though we were about to start a write. // o_wb_data <= w_cod_data; // if (i_stb) begin // Default is not to send any codewords // Do we need to broadcast a new address? // r_new_addr <= 1'b0; // casez(i_codword[35:32]) 4'b0000: begin // Set a new (arbitrary) address r_new_addr <= 1'b1; o_wb_addr <= i_codword[31:0]; end 4'b001?: begin // Set a new relative address r_new_addr <= 1'b1; o_wb_addr <= o_wb_addr + { i_codword[32:31], i_codword[29:0] }; end 4'b01??: begin // Start a write transaction, // address is alrdy set r_new_addr <= 1'b1; wb_state <= `WB_WRITE_REQUEST; end 4'b11??: begin // Start a vector read // Address is already set ... // This also depends upon the decoder working if (r_new_addr) o_stb <= 1'b1; wb_state <= `WB_READ_REQUEST; end default: ; endcase end end `WB_READ_REQUEST: begin r_new_addr <= 1'b0; if (i_wb_err) wb_state <= `WB_IDLE; o_stb <= (i_wb_err)||(i_wb_ack); if (i_wb_err) o_codword <= { 6'h5, i_wb_data[29:0] }; else o_codword <= { 3'h7, i_wb_data[31:30], r_inc, i_wb_data[29:0] }; if ((r_inc)&&(~i_wb_stall)) o_wb_addr <= o_wb_addr + 32'h001; if (~i_wb_stall) // Deal with the strobe line begin // Strobe was accepted, busy should be '1' here if (last_read_request) // (r_len != 0) // read wb_state <= `WB_ACK; end end `WB_WRITE_REQUEST: begin r_new_addr <= 1'b0; if (i_wb_err) o_codword <= { 6'h5, i_wb_data[29:0] }; else o_codword <= { 6'h2, i_wb_data[29:0] }; if ((r_inc)&&(~i_wb_stall)) o_wb_addr <= o_wb_addr + 32'h001; o_stb <= (i_wb_err)||(~i_wb_stall); // Don't need to worry about accepting anything new // here, since we'll always be busy while in this state. // Hence, we cannot accept new write requests. // if (i_wb_err) begin wb_state <= `WB_FLUSH_WRITE_REQUESTS; // end else if (~i_wb_stall) wb_state <= `WB_WAIT_ON_NEXT_WRITE; end `WB_ACK: begin r_new_addr <= 1'b0; // // No strobes are being sent out. No further // bus transactions are requested. We only need // to finish processing the last one(s) by waiting // for (and recording?) their acks. // // Process acknowledgements if (i_wb_err) o_codword <= { 6'h5, i_wb_data[29:0] }; else o_codword <= { 3'h7, i_wb_data[31:30], r_inc, i_wb_data[29:0] }; // Return a read result, or (possibly) an error // notification o_stb <= (((i_wb_ack)&&(~o_wb_we)) || (i_wb_err)); if (((last_ack)&&(i_wb_ack))||(zero_acks)||(i_wb_err)) wb_state <= `WB_IDLE; end `WB_WAIT_ON_NEXT_WRITE: begin r_new_addr <= 1'b0; o_codword <= { 6'h5, i_wb_data[29:0] }; o_stb <= (i_wb_err)||(w_new_err); o_wb_data <= w_cod_data; if (w_new_err) // Something other than a write or EOW wb_state <= `WB_IDLE; else if (i_wb_err) // Bus returns an error wb_state <= `WB_FLUSH_WRITE_REQUESTS; else if (w_newwr) // Need to make a new write request wb_state <= `WB_WRITE_REQUEST; else if (w_eow) // All done writing, wait for last ack wb_state <= `WB_ACK; end `WB_FLUSH_WRITE_REQUESTS: begin // We come in here after an error within a write // We need to wait until the command cycle finishes // issuing all its write commands before we can go back // to idle. // // In the off chance that we are in here in error, or // out of sync, we'll transition to WB_IDLE and just // issue a second error token. r_new_addr <= 1'b0; o_codword <= { 6'h5, i_wb_data[29:0] }; o_stb <= (w_new_err); if ((w_eow)||(w_new_err)) wb_state <= `WB_IDLE; end default: begin o_stb <= 1'b1; o_codword <= { 6'h3, i_wb_data[29:0] }; wb_state <= `WB_IDLE; end endcase assign o_busy = (wb_state != `WB_IDLE) &&(wb_state != `WB_WAIT_ON_NEXT_WRITE) &&(wb_state != `WB_FLUSH_WRITE_REQUESTS); assign o_wb_cyc = (wb_state == `WB_READ_REQUEST) ||(wb_state == `WB_WRITE_REQUEST) ||(wb_state == `WB_ACK) ||(wb_state == `WB_WAIT_ON_NEXT_WRITE); assign o_wb_stb = (wb_state == `WB_READ_REQUEST) ||(wb_state == `WB_WRITE_REQUEST); always @(posedge i_clk) if (wb_state == `WB_IDLE) r_acks_needed <= 10'h00; // (i_codword[35])?i_codword[9:0]:10'h00; else if ((o_wb_stb)&&(~i_wb_stall)&&(~i_wb_ack)) r_acks_needed <= r_acks_needed + 10'h01; else if (((~o_wb_stb)||(i_wb_stall))&&(i_wb_ack)) r_acks_needed <= r_acks_needed - 10'h01; always @(posedge i_clk) last_ack <= (~o_wb_stb)&&(r_acks_needed == 10'h01); always @(posedge i_clk) zero_acks <= (~o_wb_stb)&&(r_acks_needed == 10'h00); always @(posedge i_clk) if ((wb_state == `WB_IDLE)&&(i_codword[35:34] == 2'b11)) r_len <= i_codword[9:0] - 10'h01; else if ((o_wb_stb)&&(~i_wb_stall)&&(|r_len)) r_len <= r_len - 10'h01; always @(posedge i_clk) last_read_request <= (r_len[9:0] == 10'h000); endmodule
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