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[/] [zipcpu/] [trunk/] [rtl/] [peripherals/] [wbdmac.v] - Rev 50
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//////////////////////////////////////////////////////////////////////////////// // // // Filename: wbdmac.v // // Project: Zip CPU -- a small, lightweight, RISC CPU soft core // // Purpose: Wishbone DMA controller // // This module is controllable via the wishbone, and moves values from // one location in the wishbone address space to another. The amount of // memory moved at any given time can be up to 4kB, or equivalently 1kW. // Four registers control this DMA controller: a control/status register, // a length register, a source WB address and a destination WB address. // These register may be read at any time, but they may only be written // to when the controller is idle. // // The meanings of three of the setup registers should be self explanatory: // - The length register controls the total number of words to // transfer. // - The source address register controls where the DMA controller // reads from. This address may or may not be incremented // after each read, depending upon the setting in the // control/status register. // - The destination address register, which controls where the DMA // controller writes to. This address may or may not be // incremented after each write, also depending upon the // setting in the control/status register. // // It is the control/status register, at local address zero, that needs // more definition: // // Bits: // 31 R Write protect If this is set to one, it means the // write protect bit is set and the controller // is therefore idle. This bit will be set upon // completing any transfer. // 30 R Error. The controller stopped mid-transfer // after receiving a bus error. // 29 R/W inc_s_n If set to one, the source address // will not increment from one read to the next. // 28 R/W inc_d_n If set to one, the destination address // will not increment from one write to the next. // 27 R Always 0 // 26..16 R nread Indicates how many words have been read, // and not necessarily written (yet). This // combined with the cfg_len parameter should tell // exactly where the controller is at mid-transfer. // 27..16 W WriteProtect When a 12'h3db is written to these // bits, the write protect bit will be cleared. // // 15 R/W on_dev_trigger When set to '1', the controller will // wait for an external interrupt before starting. // 14..10 R/W device_id This determines which external interrupt // will trigger a transfer. // 9..0 R/W transfer_len How many bytes to transfer at one time. // The minimum transfer length is one, while zero // is mapped to a transfer length of 1kW. // // // To use this, follow this checklist: // 1. Wait for any prior DMA operation to complete // (Read address 0, wait 'till either top bit is set or cfg_len==0) // 2. Write values into length, source and destination address. // (writei(3, &vals) should be sufficient for this.) // 3. Enable the DMAC interrupt in whatever interrupt controller is present // on the system. // 4. Write the final start command to the setup/control/status register: // Set inc_s_n, inc_d_n, on_dev_trigger, dev_trigger, // appropriately for your task // Write 12'h3db to the upper word. // Set the lower word to either all zeros, or a smaller transfer // length if desired. // 5. wait() for the interrupt and the operation to complete. // Prior to completion, number of items successfully transferred // be read from the length register. If the internal buffer is // being used, then you can read how much has been read into that // buffer by reading from bits 25..16 of this control/status // register. // // Creator: Dan Gisselquist // Gisselquist Tecnology, LLC // // Copyright: 2015 // // //////////////////////////////////////////////////////////////////////////////// // // 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 // // /////////////////////////////////////////////////////////////////////////// // // module wbdmac(i_clk, i_swb_cyc, i_swb_stb, i_swb_we, i_swb_addr, i_swb_data, o_swb_ack, o_swb_stall, o_swb_data, o_mwb_cyc, o_mwb_stb, o_mwb_we, o_mwb_addr, o_mwb_data, i_mwb_ack, i_mwb_stall, i_mwb_data, i_mwb_err, i_dev_ints, o_interrupt, i_other_busmaster_requests_bus); parameter ADDRESS_WIDTH=32, LGMEMLEN = 10, DW=32, LGDV=5,AW=ADDRESS_WIDTH; input i_clk; // Slave/control wishbone inputs input i_swb_cyc, i_swb_stb, i_swb_we; input [1:0] i_swb_addr; input [(DW-1):0] i_swb_data; // Slave/control wishbone outputs output reg o_swb_ack; output wire o_swb_stall; output reg [(DW-1):0] o_swb_data; // Master/DMA wishbone control output reg o_mwb_cyc, o_mwb_stb, o_mwb_we; output reg [(AW-1):0] o_mwb_addr; output reg [(DW-1):0] o_mwb_data; // Master/DMA wishbone responses from the bus input i_mwb_ack, i_mwb_stall; input [(DW-1):0] i_mwb_data; input i_mwb_err; // The interrupt device interrupt lines input [(DW-1):0] i_dev_ints; // An interrupt to be set upon completion output reg o_interrupt; // Need to release the bus for a higher priority user input i_other_busmaster_requests_bus; reg cfg_wp; // Write protect reg cfg_err; reg [(AW-1):0] cfg_waddr, cfg_raddr, cfg_len; reg [(LGMEMLEN-1):0] cfg_blocklen_sub_one; reg cfg_incs, cfg_incd; reg [(LGDV-1):0] cfg_dev_trigger; reg cfg_on_dev_trigger; // Single block operations: We'll read, then write, up to a single // memory block here. reg [(DW-1):0] dma_mem [0:(((1<<LGMEMLEN))-1)]; reg [(LGMEMLEN):0] nread, nwritten, nacks; wire [(AW-1):0] bus_nacks; assign bus_nacks = { {(AW-LGMEMLEN-1){1'b0}}, nacks }; initial o_interrupt = 1'b0; initial o_mwb_cyc = 1'b0; initial cfg_err = 1'b0; initial cfg_wp = 1'b0; initial cfg_len = {(AW){1'b0}}; initial cfg_blocklen_sub_one = {(LGMEMLEN){1'b1}}; initial cfg_on_dev_trigger = 1'b0; always @(posedge i_clk) if ((o_mwb_cyc)&&(o_mwb_we)) // Write cycle begin if ((o_mwb_stb)&&(~i_mwb_stall)) begin nwritten <= nwritten+1; if ((nwritten == nread-1) ||(i_other_busmaster_requests_bus)) // Wishbone interruptus o_mwb_stb <= 1'b0; else if (cfg_incd) begin o_mwb_addr <= o_mwb_addr + 1; cfg_waddr <= cfg_waddr + 1; end // o_mwb_data <= dma_mem[nwritten + 1]; end if (i_mwb_err) begin o_mwb_cyc <= 1'b0; cfg_err <= 1'b1; cfg_len <= 0; nread <= 0; end else if (i_mwb_ack) begin nacks <= nacks+1; cfg_len <= cfg_len - 1; if ((nacks+1 == nwritten)&&(~o_mwb_stb)) begin o_mwb_cyc <= 1'b0; nread <= 0; o_interrupt <= (cfg_len == 1); // Turn write protect back on cfg_wp <= 1'b1; end end end else if ((o_mwb_cyc)&&(~o_mwb_we)) // Read cycle begin if ((o_mwb_stb)&&(~i_mwb_stall)) begin nacks <= nacks+1; if ((nacks == {1'b0, cfg_blocklen_sub_one}) ||(bus_nacks <= cfg_len-1) ||(i_other_busmaster_requests_bus)) // Wishbone interruptus o_mwb_stb <= 1'b0; else if (cfg_incs) begin o_mwb_addr <= o_mwb_addr + 1; end end if (i_mwb_err) begin o_mwb_cyc <= 1'b0; cfg_err <= 1'b1; cfg_len <= 0; nread <= 0; end else if (i_mwb_ack) begin nread <= nread+1; if ((~o_mwb_stb)&&(nread+1 == nacks)) begin o_mwb_cyc <= 1'b0; nacks <= 0; end if (cfg_incs) cfg_raddr <= cfg_raddr + 1; // dma_mem[nread[(LGMEMLEN-1):0]] <= i_mwb_data; end end else if ((~o_mwb_cyc)&&(nread > 0)&&(~cfg_err)) begin // Initiate/continue a write cycle o_mwb_cyc <= 1'b1; o_mwb_stb <= 1'b1; o_mwb_we <= 1'b1; // o_mwb_data <= dma_mem[0]; o_mwb_addr <= cfg_waddr; // nwritten <= 0; // Can't set to zero, in case we're // nacks <= 0; // continuing a cycle end else if ((~o_mwb_cyc)&&(nread == 0)&&(cfg_len>0)&&(~cfg_wp) &&((~cfg_on_dev_trigger) ||(i_dev_ints[cfg_dev_trigger]))) begin // Initiate a read cycle o_mwb_cyc <= 1'b1; o_mwb_stb <= 1'b1; o_mwb_we <= 1'b0; o_mwb_addr<= cfg_raddr; nwritten <= 0; nread <= 0; nacks <= 0; end else begin o_mwb_cyc <= 1'b0; o_mwb_stb <= 1'b0; o_mwb_we <= 1'b0; o_mwb_addr <= cfg_raddr; o_interrupt<= 1'b0; nwritten <= 0; if ((i_swb_cyc)&&(i_swb_stb)&&(i_swb_we)) begin cfg_wp <= 1'b1; case(i_swb_addr) 2'b00: begin cfg_wp <= (i_swb_data[27:16]!=12'hfed); cfg_blocklen_sub_one <= i_swb_data[(LGMEMLEN-1):0]-1; cfg_dev_trigger <= i_swb_data[14:10]; cfg_on_dev_trigger <= i_swb_data[15]; cfg_incs <= ~i_swb_data[29]; cfg_incd <= ~i_swb_data[28]; cfg_err <= 1'b0; end 2'b01: cfg_len <= i_swb_data[(AW-1):0]; 2'b10: cfg_raddr <= i_swb_data[(AW-1):0]; 2'b11: cfg_waddr <= i_swb_data[(AW-1):0]; endcase end end // // This is tricky. In order for Vivado to consider dma_mem to be a // proper memory, it must have a simple address fed into it. Hence // the read_address (rdaddr) register. The problem is that this // register must always be one greater than the address we actually // want to read from, unless we are idling. So ... the math is touchy. // reg [(LGMEMLEN-1):0] rdaddr; always @(posedge i_clk) if ((o_mwb_cyc)&&(o_mwb_we)&&(o_mwb_stb)&&(~i_mwb_stall)) // This would be the normal advance, save that we are // already one ahead of nwritten rdaddr <= rdaddr + 1; // {{(LGMEMLEN-1){1'b0}},1}; else if ((~o_mwb_cyc)&&(nread > 0)&&(~cfg_err)) // Here's where we do our extra advance rdaddr <= nwritten[(LGMEMLEN-1):0]+1; else if ((~o_mwb_cyc)||(~o_mwb_we)) rdaddr <= nwritten[(LGMEMLEN-1):0]; always @(posedge i_clk) if ((~o_mwb_cyc)||((o_mwb_we)&&(o_mwb_stb)&&(~i_mwb_stall))) o_mwb_data <= dma_mem[rdaddr]; always @(posedge i_clk) if ((o_mwb_cyc)&&(~o_mwb_we)&&(i_mwb_ack)) dma_mem[nread[(LGMEMLEN-1):0]] <= i_mwb_data; always @(posedge i_clk) casez(i_swb_addr) 2'b00: o_swb_data <= { ~cfg_wp, cfg_err, ~cfg_incs, ~cfg_incd, 1'b0, nread, cfg_on_dev_trigger, cfg_dev_trigger, cfg_blocklen_sub_one }; 2'b01: o_swb_data <= { {(DW-AW){1'b0}}, cfg_len }; 2'b10: o_swb_data <= { {(DW-AW){1'b0}}, cfg_raddr}; 2'b11: o_swb_data <= { {(DW-AW){1'b0}}, cfg_waddr}; endcase always @(posedge i_clk) if ((i_swb_cyc)&&(i_swb_stb)) // &&(~i_swb_we)) o_swb_ack <= 1'b1; // else if ((i_swb_cyc)&&(i_swb_stb)&&(i_swb_we)&&(~o_mwb_cyc)&&(nread == 0)) else o_swb_ack <= 1'b0; assign o_swb_stall = 1'b0; endmodule
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