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dgisselq |
////////////////////////////////////////////////////////////////////////////////
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//
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//
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// Filename: wbdmac.v
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//
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// Project: Zip CPU -- a small, lightweight, RISC CPU soft core
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//
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// Purpose: Wishbone DMA controller
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//
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// This module is controllable via the wishbone, and moves values from
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// one location in the wishbone address space to another. The amount of
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// memory moved at any given time can be up to 4kB, or equivalently 1kW.
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// Four registers control this DMA controller: a control/status register,
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// a length register, a source WB address and a destination WB address.
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// These register may be read at any time, but they may only be written
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// to when the controller is idle.
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//
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// The meanings of three of the setup registers should be self explanatory:
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// - The length register controls the total number of words to
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// transfer.
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// - The source address register controls where the DMA controller
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// reads from. This address may or may not be incremented
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// after each read, depending upon the setting in the
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// control/status register.
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// - The destination address register, which controls where the DMA
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// controller writes to. This address may or may not be
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// incremented after each write, also depending upon the
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// setting in the control/status register.
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//
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// It is the control/status register, at local address zero, that needs
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// more definition:
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//
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// Bits:
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// 31 R Write protect If this is set to one, it means the
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// write protect bit is set and the controller
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// is therefore idle. This bit will be set upon
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// completing any transfer.
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// 30 R Error. The controller stopped mid-transfer
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// after receiving a bus error.
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// 29 R/W inc_s_n If set to one, the source address
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// will not increment from one read to the next.
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// 28 R/W inc_d_n If set to one, the destination address
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// will not increment from one write to the next.
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// 27 R Always 0
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// 26..16 R nread Indicates how many words have been read,
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// and not necessarily written (yet). This
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// combined with the cfg_len parameter should tell
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// exactly where the controller is at mid-transfer.
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// 27..16 W WriteProtect When a 12'h3db is written to these
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// bits, the write protect bit will be cleared.
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//
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// 15 R/W on_dev_trigger When set to '1', the controller will
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// wait for an external interrupt before starting.
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// 14..10 R/W device_id This determines which external interrupt
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// will trigger a transfer.
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// 9..0 R/W transfer_len How many bytes to transfer at one time.
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// The minimum transfer length is one, while zero
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// is mapped to a transfer length of 1kW.
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//
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//
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// To use this, follow this checklist:
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// 1. Wait for any prior DMA operation to complete
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// (Read address 0, wait 'till either top bit is set or cfg_len==0)
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// 2. Write values into length, source and destination address.
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// (writei(3, &vals) should be sufficient for this.)
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// 3. Enable the DMAC interrupt in whatever interrupt controller is present
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// on the system.
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// 4. Write the final start command to the setup/control/status register:
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// Set inc_s_n, inc_d_n, on_dev_trigger, dev_trigger,
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// appropriately for your task
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// Write 12'h3db to the upper word.
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// Set the lower word to either all zeros, or a smaller transfer
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// length if desired.
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// 5. wait() for the interrupt and the operation to complete.
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// Prior to completion, number of items successfully transferred
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// be read from the length register. If the internal buffer is
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// being used, then you can read how much has been read into that
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// buffer by reading from bits 25..16 of this control/status
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// register.
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//
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// Creator: Dan Gisselquist
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// Gisselquist Tecnology, LLC
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//
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// Copyright: 2015
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//
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//
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////////////////////////////////////////////////////////////////////////////////
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//
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// Copyright (C) 2015, Gisselquist Technology, LLC
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//
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// This program is free software (firmware): you can redistribute it and/or
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// modify it under the terms of the GNU General Public License as published
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// by the Free Software Foundation, either version 3 of the License, or (at
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// your option) any later version.
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//
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// This program is distributed in the hope that it will be useful, but WITHOUT
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// ANY WARRANTY; without even the implied warranty of MERCHANTIBILITY or
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// FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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// for more details.
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//
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// License: GPL, v3, as defined and found on www.gnu.org,
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// http://www.gnu.org/licenses/gpl.html
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//
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//
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///////////////////////////////////////////////////////////////////////////
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//
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//
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module wbdmac(i_clk,
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i_swb_cyc, i_swb_stb, i_swb_we, i_swb_addr, i_swb_data,
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o_swb_ack, o_swb_stall, o_swb_data,
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o_mwb_cyc, o_mwb_stb, o_mwb_we, o_mwb_addr, o_mwb_data,
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i_mwb_ack, i_mwb_stall, i_mwb_data, i_mwb_err,
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i_dev_ints,
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o_interrupt,
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i_other_busmaster_requests_bus);
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parameter LGMEMLEN = 10, DW=32, LGDV=5;
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input i_clk;
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// Slave/control wishbone inputs
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input i_swb_cyc, i_swb_stb, i_swb_we;
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input [1:0] i_swb_addr;
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input [(DW-1):0] i_swb_data;
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// Slave/control wishbone outputs
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output reg o_swb_ack;
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output wire o_swb_stall;
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output reg [(DW-1):0] o_swb_data;
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// Master/DMA wishbone control
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output reg o_mwb_cyc, o_mwb_stb, o_mwb_we;
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output reg [(DW-1):0] o_mwb_addr, o_mwb_data;
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// Master/DMA wishbone responses from the bus
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input i_mwb_ack, i_mwb_stall;
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input [(DW-1):0] i_mwb_data;
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input i_mwb_err;
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// The interrupt device interrupt lines
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input [(DW-1):0] i_dev_ints;
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// An interrupt to be set upon completion
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output reg o_interrupt;
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// Need to release the bus for a higher priority user
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input i_other_busmaster_requests_bus;
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reg cfg_wp; // Write protect
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reg cfg_err;
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reg [(DW-1):0] cfg_waddr, cfg_raddr, cfg_len;
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reg [(LGMEMLEN-1):0] cfg_blocklen_sub_one;
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reg cfg_incs, cfg_incd;
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reg [(LGDV-1):0] cfg_dev_trigger;
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reg cfg_on_dev_trigger;
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// Single block operations: We'll read, then write, up to a single
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// memory block here.
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reg [(DW-1):0] dma_mem [0:(((1<<LGMEMLEN))-1)];
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reg [(LGMEMLEN):0] nread, nwritten, nacks;
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wire [(DW-1):0] bus_nacks;
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assign bus_nacks = { {(DW-LGMEMLEN-1){1'b0}}, nacks };
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initial o_interrupt = 1'b0;
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initial o_mwb_cyc = 1'b0;
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initial cfg_err = 1'b0;
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initial cfg_wp = 1'b0;
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initial cfg_len = 32'h00;
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initial cfg_blocklen_sub_one = {(LGMEMLEN){1'b1}};
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initial cfg_on_dev_trigger = 1'b0;
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always @(posedge i_clk)
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if ((o_mwb_cyc)&&(o_mwb_we)) // Write cycle
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begin
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if ((o_mwb_stb)&&(~i_mwb_stall))
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begin
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nwritten <= nwritten+1;
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if ((nwritten == nread-1)
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||(i_other_busmaster_requests_bus))
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// Wishbone interruptus
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o_mwb_stb <= 1'b0;
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else if (cfg_incd) begin
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o_mwb_addr <= o_mwb_addr + 1;
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cfg_waddr <= cfg_waddr + 1;
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end
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// o_mwb_data <= dma_mem[nwritten + 1];
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end
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if (i_mwb_err)
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begin
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o_mwb_cyc <= 1'b0;
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cfg_err <= 1'b1;
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cfg_len <= 0;
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nread <= 0;
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end else if (i_mwb_ack)
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begin
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nacks <= nacks+1;
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cfg_len <= cfg_len - 1;
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if ((nacks+1 == nwritten)&&(~o_mwb_stb))
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begin
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o_mwb_cyc <= 1'b0;
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nread <= 0;
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o_interrupt <= (cfg_len == 1);
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// Turn write protect back on
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cfg_wp <= 1'b1;
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end
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end
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end else if ((o_mwb_cyc)&&(~o_mwb_we)) // Read cycle
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begin
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if ((o_mwb_stb)&&(~i_mwb_stall))
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begin
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nacks <= nacks+1;
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if ((nacks == {1'b0, cfg_blocklen_sub_one})
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||(bus_nacks <= cfg_len-1)
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||(i_other_busmaster_requests_bus))
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// Wishbone interruptus
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o_mwb_stb <= 1'b0;
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else if (cfg_incs) begin
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o_mwb_addr <= o_mwb_addr + 1;
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end
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end
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if (i_mwb_err)
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begin
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o_mwb_cyc <= 1'b0;
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cfg_err <= 1'b1;
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cfg_len <= 0;
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nread <= 0;
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end else if (i_mwb_ack)
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begin
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nread <= nread+1;
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if ((~o_mwb_stb)&&(nread+1 == nacks))
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begin
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o_mwb_cyc <= 1'b0;
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nacks <= 0;
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end
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if (cfg_incs)
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cfg_raddr <= cfg_raddr + 1;
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// dma_mem[nread[(LGMEMLEN-1):0]] <= i_mwb_data;
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end
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end else if ((~o_mwb_cyc)&&(nread > 0)&&(~cfg_err))
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begin // Initiate/continue a write cycle
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o_mwb_cyc <= 1'b1;
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o_mwb_stb <= 1'b1;
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o_mwb_we <= 1'b1;
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// o_mwb_data <= dma_mem[0];
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o_mwb_addr <= cfg_waddr;
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// nwritten <= 0; // Can't set to zero, in case we're
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// nacks <= 0; // continuing a cycle
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end else if ((~o_mwb_cyc)&&(nread == 0)&&(cfg_len>0)&&(~cfg_wp)
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&&((~cfg_on_dev_trigger)
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||(i_dev_ints[cfg_dev_trigger])))
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begin // Initiate a read cycle
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o_mwb_cyc <= 1'b1;
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o_mwb_stb <= 1'b1;
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o_mwb_we <= 1'b0;
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o_mwb_addr<= cfg_raddr;
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nwritten <= 0;
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nread <= 0;
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nacks <= 0;
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end else begin
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o_mwb_cyc <= 1'b0;
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o_mwb_stb <= 1'b0;
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o_mwb_we <= 1'b0;
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o_mwb_addr <= cfg_raddr;
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o_interrupt<= 1'b0;
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nwritten <= 0;
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if ((i_swb_cyc)&&(i_swb_stb)&&(i_swb_we))
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begin
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cfg_wp <= 1'b1;
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case(i_swb_addr)
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2'b00: begin
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cfg_wp <= (i_swb_data[27:16]!=12'hfed);
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cfg_blocklen_sub_one
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<= i_swb_data[(LGMEMLEN-1):0]-1;
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cfg_dev_trigger <= i_swb_data[14:10];
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cfg_on_dev_trigger <= i_swb_data[15];
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cfg_incs <= ~i_swb_data[29];
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cfg_incd <= ~i_swb_data[28];
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cfg_err <= 1'b0;
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end
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2'b01: cfg_len <= i_swb_data;
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2'b10: cfg_raddr <= i_swb_data;
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2'b11: cfg_waddr <= i_swb_data;
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endcase
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end
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end
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//
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// This is tricky. In order for Vivado to consider dma_mem to be a
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// proper memory, it must have a simple address fed into it. Hence
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// the read_address (rdaddr) register. The problem is that this
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// register must always be one greater than the address we actually
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// want to read from, unless we are idling. So ... the math is touchy.
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//
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reg [(LGMEMLEN-1):0] rdaddr;
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always @(posedge i_clk)
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if ((o_mwb_cyc)&&(o_mwb_we)&&(o_mwb_stb)&&(~i_mwb_stall))
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// This would be the normal advance, save that we are
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// already one ahead of nwritten
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rdaddr <= rdaddr + 1; // {{(LGMEMLEN-1){1'b0}},1};
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else if ((~o_mwb_cyc)&&(nread > 0)&&(~cfg_err))
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// Here's where we do our extra advance
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rdaddr <= nwritten[(LGMEMLEN-1):0]+1;
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else if ((~o_mwb_cyc)||(~o_mwb_we))
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rdaddr <= nwritten[(LGMEMLEN-1):0];
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always @(posedge i_clk)
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if ((~o_mwb_cyc)||((o_mwb_we)&&(o_mwb_stb)&&(~i_mwb_stall)))
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o_mwb_data <= dma_mem[rdaddr];
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always @(posedge i_clk)
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if ((o_mwb_cyc)&&(~o_mwb_we)&&(i_mwb_ack))
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dma_mem[nread[(LGMEMLEN-1):0]] <= i_mwb_data;
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always @(posedge i_clk)
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| 307 |
|
|
casez(i_swb_addr)
|
| 308 |
|
|
2'b00: o_swb_data <= { ~cfg_wp, cfg_err,
|
| 309 |
|
|
~cfg_incs, ~cfg_incd,
|
| 310 |
|
|
1'b0, nread,
|
| 311 |
|
|
cfg_on_dev_trigger, cfg_dev_trigger,
|
| 312 |
|
|
cfg_blocklen_sub_one
|
| 313 |
|
|
};
|
| 314 |
|
|
2'b01: o_swb_data <= cfg_len;
|
| 315 |
|
|
2'b10: o_swb_data <= cfg_raddr;
|
| 316 |
|
|
2'b11: o_swb_data <= cfg_waddr;
|
| 317 |
|
|
endcase
|
| 318 |
|
|
|
| 319 |
|
|
always @(posedge i_clk)
|
| 320 |
|
|
if ((i_swb_cyc)&&(i_swb_stb)) // &&(~i_swb_we))
|
| 321 |
|
|
o_swb_ack <= 1'b1;
|
| 322 |
|
|
// else if ((i_swb_cyc)&&(i_swb_stb)&&(i_swb_we)&&(~o_mwb_cyc)&&(nread == 0))
|
| 323 |
|
|
else
|
| 324 |
|
|
o_swb_ack <= 1'b0;
|
| 325 |
|
|
|
| 326 |
|
|
assign o_swb_stall = 1'b0;
|
| 327 |
|
|
|
| 328 |
|
|
endmodule
|
| 329 |
|
|
|
