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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 Technology, LLC
//
////////////////////////////////////////////////////////////////////////////////
//
// Copyright (C) 2015-2016, 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 DMA_IDLE        3'b000
`define DMA_WAIT        3'b001
`define DMA_READ_REQ    3'b010
`define DMA_READ_ACK    3'b011
`define DMA_PRE_WRITE   3'b100
`define DMA_WRITE_REQ   3'b101
`define DMA_WRITE_ACK   3'b110
 
module wbdmac(i_clk, i_rst,
                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);
        parameter       ADDRESS_WIDTH=32, LGMEMLEN = 10,
                        DW=32, LGDV=5,AW=ADDRESS_WIDTH;
        input                   i_clk, i_rst;
        // 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  wire            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
        //      This logic had lots of problems, so it is being
        //      removed.  If you want to make sure the bus is available
        //      for a higher priority user, adjust the transfer length
        //      accordingly.
        //
        // input                        i_other_busmaster_requests_bus;
        //
 
 
        reg     [2:0]            dma_state;
        reg                     cfg_err, cfg_len_nonzero;
        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, nwacks, nracks;
        wire    [(AW-1):0]       bus_nracks;
        assign  bus_nracks = { {(AW-LGMEMLEN-1){1'b0}}, nracks };
 
        reg     last_read_request, last_read_ack,
                last_write_request, last_write_ack;
        reg     trigger, abort;
 
        initial dma_state = `DMA_IDLE;
        initial o_interrupt = 1'b0;
        initial cfg_len     = {(AW){1'b0}};
        initial cfg_blocklen_sub_one = {(LGMEMLEN){1'b1}};
        initial cfg_on_dev_trigger = 1'b0;
        initial cfg_len_nonzero = 1'b0;
        always @(posedge i_clk)
        case(dma_state)
        `DMA_IDLE: begin
                o_mwb_addr <= cfg_raddr;
                nwritten   <= 0;
                nread      <= 0;
                nracks     <= 0;
                nwacks     <= 0;
                cfg_len_nonzero <= (|cfg_len);
 
                // When the slave wishbone writes, and we are in this 
                // (ready) configuration, then allow the DMA to be controlled
                // and thus to start.
                if ((i_swb_stb)&&(i_swb_we))
                begin
                        case(i_swb_addr)
                        2'b00: begin
                                if ((i_swb_data[27:16] == 12'hfed)
                                                &&(cfg_len_nonzero))
                                        dma_state <= `DMA_WAIT;
                                cfg_blocklen_sub_one
                                        <= i_swb_data[(LGMEMLEN-1):0]
                                        + {(LGMEMLEN){1'b1}};
                                        // i.e. -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];
                                end
                        2'b01: begin
                                cfg_len   <=  i_swb_data[(AW-1):0];
                                cfg_len_nonzero <= (|i_swb_data[(AW-1):0]);
                                end
                        2'b10: cfg_raddr <=  i_swb_data[(AW-1):0];
                        2'b11: cfg_waddr <=  i_swb_data[(AW-1):0];
                        endcase
                end end
        `DMA_WAIT: begin
                o_mwb_addr <= cfg_raddr;
                nracks     <= 0;
                nwacks     <= 0;
                nwritten   <= 0;
                nread      <= 0;
                if (abort)
                        dma_state <= `DMA_IDLE;
                else if (trigger)
                        dma_state <= `DMA_READ_REQ;
                end
        `DMA_READ_REQ: begin
                nwritten  <= 0;
 
                if (~i_mwb_stall)
                begin
                        // Number of read acknowledgements needed
                        nracks <= nracks+1;
                        if (last_read_request)
        //((nracks == {1'b0, cfg_blocklen_sub_one})||(bus_nracks == cfg_len-1))
                                // Wishbone interruptus
                                dma_state <= `DMA_READ_ACK;
                        if (cfg_incs)
                                o_mwb_addr <= o_mwb_addr
                                                + {{(AW-1){1'b0}},1'b1};
                end
 
                if (i_mwb_err)
                begin
                        cfg_len <= 0;
                        dma_state <= `DMA_IDLE;
                end
                if (abort)
                        dma_state <= `DMA_IDLE;
                if (i_mwb_ack)
                begin
                        nread <= nread+1;
                        if (cfg_incs)
                                cfg_raddr  <= cfg_raddr
                                                + {{(AW-1){1'b0}},1'b1};
                end end
        `DMA_READ_ACK: begin
                nwritten  <= 0;
 
                if (i_mwb_err)
                begin
                        cfg_len <= 0;
                        dma_state <= `DMA_IDLE;
                end else if (i_mwb_ack)
                begin
                        nread <= nread+1;
                        if (last_read_ack) // (nread+1 == nracks)
                                dma_state  <= `DMA_PRE_WRITE;
                        if (cfg_incs)
                                cfg_raddr  <= cfg_raddr
                                                + {{(AW-1){1'b0}},1'b1};
                end
                if (abort)
                        dma_state <= `DMA_IDLE;
                end
        `DMA_PRE_WRITE: begin
                o_mwb_addr <= cfg_waddr;
                dma_state <= (abort)?`DMA_IDLE:`DMA_WRITE_REQ;
                end
        `DMA_WRITE_REQ: begin
                if (~i_mwb_stall)
                begin
                        nwritten <= nwritten+1;
                        if (last_write_request) // (nwritten == nread-1)
                                // Wishbone interruptus
                                dma_state <= `DMA_WRITE_ACK;
                        if (cfg_incd)
                        begin
                                o_mwb_addr <= o_mwb_addr
                                                + {{(AW-1){1'b0}},1'b1};
                                cfg_waddr  <= cfg_waddr
                                                + {{(AW-1){1'b0}},1'b1};
                        end
                end
 
                if (i_mwb_err)
                begin
                        cfg_len  <= 0;
                        dma_state <= `DMA_IDLE;
                end
                if (i_mwb_ack)
                begin
                        nwacks <= nwacks+1;
                        cfg_len <= cfg_len +{(AW){1'b1}}; // -1
                end
                if (abort)
                        dma_state <= `DMA_IDLE;
                end
        `DMA_WRITE_ACK: begin
                if (i_mwb_err)
                begin
                        cfg_len  <= 0;
                        nread    <= 0;
                        dma_state <= `DMA_IDLE;
                end else if (i_mwb_ack)
                begin
                        nwacks <= nwacks+1;
                        cfg_len <= cfg_len +{(AW){1'b1}};//cfg_len -= 1;
                        if (last_write_ack) // (nwacks+1 == nwritten)
                        begin
                                nread <= 0;
                                dma_state <= (cfg_len == 1)?`DMA_IDLE:`DMA_WAIT;
                        end
                end
 
                if (abort)
                        dma_state <= `DMA_IDLE;
                end
        default:
                dma_state <= `DMA_IDLE;
        endcase
 
        initial o_interrupt = 1'b0;
        always @(posedge i_clk)
                o_interrupt <= ((dma_state == `DMA_WRITE_ACK)&&(i_mwb_ack)
                                        &&(last_write_ack)
                                        &&(cfg_len == {{(AW-1){1'b0}},1'b1}))
                                ||((dma_state != `DMA_IDLE)&&(i_mwb_err));
 
        initial cfg_err = 1'b0;
        always @(posedge i_clk)
                if (dma_state == `DMA_IDLE)
                begin
                        if ((i_swb_stb)&&(i_swb_we)&&(i_swb_addr==2'b00))
                                cfg_err <= 1'b0;
                end else if (((i_mwb_err)&&(o_mwb_cyc))||(abort))
                        cfg_err <= 1'b1;
 
        initial last_read_request = 1'b0;
        always @(posedge i_clk)
                if ((dma_state == `DMA_WAIT)||(dma_state == `DMA_READ_REQ))
                begin
                        if ((~i_mwb_stall)&&(dma_state == `DMA_READ_REQ))
                        begin
                                last_read_request <=
                                (nracks + 1 == { 1'b0, cfg_blocklen_sub_one})
                                        ||(bus_nracks == cfg_len-2);
                        end else
                                last_read_request <=
                                        (nracks== { 1'b0, cfg_blocklen_sub_one})
                                        ||(bus_nracks == cfg_len-1);
                end else
                        last_read_request <= 1'b0;
 
        initial last_read_ack = 1'b0;
        always @(posedge i_clk)
                if ((dma_state == `DMA_READ_REQ)||(dma_state == `DMA_READ_ACK))
                begin
                        if ((i_mwb_ack)&&((~o_mwb_stb)||(i_mwb_stall)))
                                last_read_ack <= (nread+2 == nracks);
                        else
                                last_read_ack <= (nread+1 == nracks);
                end else
                        last_read_ack <= 1'b0;
 
        initial last_write_request = 1'b0;
        always @(posedge i_clk)
                if (dma_state == `DMA_PRE_WRITE)
                        last_write_request <= (nread <= 1);
                else if (dma_state == `DMA_WRITE_REQ)
                begin
                        if (i_mwb_stall)
                                last_write_request <= (nwritten >= nread-1);
                        else
                                last_write_request <= (nwritten >= nread-2);
                end else
                        last_write_request <= 1'b0;
 
        initial last_write_ack = 1'b0;
        always @(posedge i_clk)
                if((dma_state == `DMA_WRITE_REQ)||(dma_state == `DMA_WRITE_ACK))
                begin
                        if ((i_mwb_ack)&&((~o_mwb_stb)||(i_mwb_stall)))
                                last_write_ack <= (nwacks+2 == nwritten);
                        else
                                last_write_ack <= (nwacks+1 == nwritten);
                end else
                        last_write_ack <= 1'b0;
 
        assign  o_mwb_cyc = (dma_state == `DMA_READ_REQ)
                        ||(dma_state == `DMA_READ_ACK)
                        ||(dma_state == `DMA_WRITE_REQ)
                        ||(dma_state == `DMA_WRITE_ACK);
 
        assign  o_mwb_stb = (dma_state == `DMA_READ_REQ)
                        ||(dma_state == `DMA_WRITE_REQ);
 
        assign  o_mwb_we = (dma_state == `DMA_PRE_WRITE)
                        ||(dma_state == `DMA_WRITE_REQ)
                        ||(dma_state == `DMA_WRITE_ACK);
 
        //
        // 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((dma_state == `DMA_IDLE)||(dma_state == `DMA_WAIT)
                                ||(dma_state == `DMA_WRITE_ACK))
                        rdaddr <= 0;
                else if ((dma_state == `DMA_PRE_WRITE)
                                ||((dma_state==`DMA_WRITE_REQ)&&(~i_mwb_stall)))
                        rdaddr <= rdaddr + {{(LGMEMLEN-1){1'b0}},1'b1};
        always @(posedge i_clk)
                if ((dma_state != `DMA_WRITE_REQ)||(~i_mwb_stall))
                        o_mwb_data <= dma_mem[rdaddr];
        always @(posedge i_clk)
                if((dma_state == `DMA_READ_REQ)||(dma_state == `DMA_READ_ACK))
                        dma_mem[nread[(LGMEMLEN-1):0]] <= i_mwb_data;
 
        always @(posedge i_clk)
                casez(i_swb_addr)
                2'b00: o_swb_data <= {  (dma_state != `DMA_IDLE), 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
 
        // This causes us to wait a minimum of two clocks before starting: One
        // to go into the wait state, and then one while in the wait state to
        // develop the trigger.
        initial trigger = 1'b0;
        always @(posedge i_clk)
                trigger <=  (dma_state == `DMA_WAIT)
                                &&((~cfg_on_dev_trigger)
                                        ||(i_dev_ints[cfg_dev_trigger]));
 
        // Ack any access.  We'll quietly ignore any access where we are busy,
        // but ack it anyway.  In other words, before writing to the device,
        // double check that it isn't busy, and then write.
        always @(posedge i_clk)
                o_swb_ack <= (i_swb_stb);
 
        assign  o_swb_stall = 1'b0;
 
        initial abort = 1'b0;
        always @(posedge i_clk)
                abort <= (i_rst)||((i_swb_stb)&&(i_swb_we)
                        &&(i_swb_addr == 2'b00)
                        &&(i_swb_data == 32'hffed0000));
 
endmodule
 

Line No.	Rev	Author	Line
1	3	dgisselq	`////////////////////////////////////////////////////////////////////////////////`
2			`//`
3			`//`
4			`// Filename: wbdmac.v`
5			`//`
6			`// Project: Zip CPU -- a small, lightweight, RISC CPU soft core`
7			`//`
8			`// Purpose: Wishbone DMA controller`
9			`//`
10			`// This module is controllable via the wishbone, and moves values from`
11			`// one location in the wishbone address space to another. The amount of`
12			`// memory moved at any given time can be up to 4kB, or equivalently 1kW.`
13			`// Four registers control this DMA controller: a control/status register,`
14			`// a length register, a source WB address and a destination WB address.`
15			`// These register may be read at any time, but they may only be written`
16			`// to when the controller is idle.`
17			`//`
18			`// The meanings of three of the setup registers should be self explanatory:`
19			`// - The length register controls the total number of words to`
20			`// transfer.`
21			`// - The source address register controls where the DMA controller`
22			`// reads from. This address may or may not be incremented`
23			`// after each read, depending upon the setting in the`
24			`// control/status register.`
25			`// - The destination address register, which controls where the DMA`
26			`// controller writes to. This address may or may not be`
27			`// incremented after each write, also depending upon the`
28			`// setting in the control/status register.`
29			`//`
30			`// It is the control/status register, at local address zero, that needs`
31			`// more definition:`
32			`//`
33			`// Bits:`
34			`// 31 R Write protect If this is set to one, it means the`
35			`// write protect bit is set and the controller`
36			`// is therefore idle. This bit will be set upon`
37			`// completing any transfer.`
38			`// 30 R Error. The controller stopped mid-transfer`
39			`// after receiving a bus error.`
40			`// 29 R/W inc_s_n If set to one, the source address`
41			`// will not increment from one read to the next.`
42			`// 28 R/W inc_d_n If set to one, the destination address`
43			`// will not increment from one write to the next.`
44			`// 27 R Always 0`
45			`// 26..16 R nread Indicates how many words have been read,`
46			`// and not necessarily written (yet). This`
47			`// combined with the cfg_len parameter should tell`
48			`// exactly where the controller is at mid-transfer.`
49			`// 27..16 W WriteProtect When a 12'h3db is written to these`
50			`// bits, the write protect bit will be cleared.`
51			`//`
52			`// 15 R/W on_dev_trigger When set to '1', the controller will`
53			`// wait for an external interrupt before starting.`
54			`// 14..10 R/W device_id This determines which external interrupt`
55			`// will trigger a transfer.`
56			`// 9..0 R/W transfer_len How many bytes to transfer at one time.`
57			`// The minimum transfer length is one, while zero`
58			`// is mapped to a transfer length of 1kW.`
59			`//`
60			`//`
61			`// To use this, follow this checklist:`
62			`// 1. Wait for any prior DMA operation to complete`
63			`// (Read address 0, wait 'till either top bit is set or cfg_len==0)`
64			`// 2. Write values into length, source and destination address.`
65			`// (writei(3, &vals) should be sufficient for this.)`
66			`// 3. Enable the DMAC interrupt in whatever interrupt controller is present`
67			`// on the system.`
68			`// 4. Write the final start command to the setup/control/status register:`
69			`// Set inc_s_n, inc_d_n, on_dev_trigger, dev_trigger,`
70			`// appropriately for your task`
71			`// Write 12'h3db to the upper word.`
72			`// Set the lower word to either all zeros, or a smaller transfer`
73			`// length if desired.`
74			`// 5. wait() for the interrupt and the operation to complete.`
75			`// Prior to completion, number of items successfully transferred`
76			`// be read from the length register. If the internal buffer is`
77			`// being used, then you can read how much has been read into that`
78			`// buffer by reading from bits 25..16 of this control/status`
79			`// register.`
80			`//`
81			`// Creator: Dan Gisselquist`
82			`// Gisselquist Technology, LLC`
83			`//`
84			`////////////////////////////////////////////////////////////////////////////////`
85			`//`
86			`// Copyright (C) 2015-2016, Gisselquist Technology, LLC`
87			`//`
88			`// This program is free software (firmware): you can redistribute it and/or`
89			`// modify it under the terms of the GNU General Public License as published`
90			`// by the Free Software Foundation, either version 3 of the License, or (at`
91			`// your option) any later version.`
92			`//`
93			`// This program is distributed in the hope that it will be useful, but WITHOUT`
94			`// ANY WARRANTY; without even the implied warranty of MERCHANTIBILITY or`
95			`// FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License`
96			`// for more details.`
97			`//`
98			`// License: GPL, v3, as defined and found on www.gnu.org,`
99			`// http://www.gnu.org/licenses/gpl.html`
100			`//`
101			`//`
102			`///////////////////////////////////////////////////////////////////////////`
103			`//`
104			`//`
105			`define DMA_IDLE 3'b000
106			`define DMA_WAIT 3'b001
107			`define DMA_READ_REQ 3'b010
108			`define DMA_READ_ACK 3'b011
109			`define DMA_PRE_WRITE 3'b100
110			`define DMA_WRITE_REQ 3'b101
111			`define DMA_WRITE_ACK 3'b110
112
113			`module wbdmac(i_clk, i_rst,`
114			`i_swb_cyc, i_swb_stb, i_swb_we, i_swb_addr, i_swb_data,`
115			`o_swb_ack, o_swb_stall, o_swb_data,`
116			`o_mwb_cyc, o_mwb_stb, o_mwb_we, o_mwb_addr, o_mwb_data,`
117			`i_mwb_ack, i_mwb_stall, i_mwb_data, i_mwb_err,`
118			`i_dev_ints,`
119			`o_interrupt);`
120			`parameter ADDRESS_WIDTH=32, LGMEMLEN = 10,`
121			`DW=32, LGDV=5,AW=ADDRESS_WIDTH;`
122			`input i_clk, i_rst;`
123			`// Slave/control wishbone inputs`
124			`input i_swb_cyc, i_swb_stb, i_swb_we;`
125			`input [1:0] i_swb_addr;`
126			`input [(DW-1):0] i_swb_data;`
127			`// Slave/control wishbone outputs`
128			`output reg o_swb_ack;`
129			`output wire o_swb_stall;`
130			`output reg [(DW-1):0] o_swb_data;`
131			`// Master/DMA wishbone control`
132			`output wire o_mwb_cyc, o_mwb_stb, o_mwb_we;`
133			`output reg [(AW-1):0] o_mwb_addr;`
134			`output reg [(DW-1):0] o_mwb_data;`
135			`// Master/DMA wishbone responses from the bus`
136			`input i_mwb_ack, i_mwb_stall;`
137			`input [(DW-1):0] i_mwb_data;`
138			`input i_mwb_err;`
139			`// The interrupt device interrupt lines`
140			`input [(DW-1):0] i_dev_ints;`
141			`// An interrupt to be set upon completion`
142			`output reg o_interrupt;`
143			`// Need to release the bus for a higher priority user`
144			`// This logic had lots of problems, so it is being`
145			`// removed. If you want to make sure the bus is available`
146			`// for a higher priority user, adjust the transfer length`
147			`// accordingly.`
148			`//`
149			`// input i_other_busmaster_requests_bus;`
150			`//`
151
152
153			`reg [2:0] dma_state;`
154			`reg cfg_err, cfg_len_nonzero;`
155			`reg [(AW-1):0] cfg_waddr, cfg_raddr, cfg_len;`
156			`reg [(LGMEMLEN-1):0] cfg_blocklen_sub_one;`
157			`reg cfg_incs, cfg_incd;`
158			`reg [(LGDV-1):0] cfg_dev_trigger;`
159			`reg cfg_on_dev_trigger;`
160
161			`// Single block operations: We'll read, then write, up to a single`
162			`// memory block here.`
163
164			`reg [(DW-1):0] dma_mem [0:(((1<<LGMEMLEN))-1)];`
165			`reg [(LGMEMLEN):0] nread, nwritten, nwacks, nracks;`
166			`wire [(AW-1):0] bus_nracks;`
167			`assign bus_nracks = { {(AW-LGMEMLEN-1){1'b0}}, nracks };`
168
169			`reg last_read_request, last_read_ack,`
170			`last_write_request, last_write_ack;`
171			`reg trigger, abort;`
172
173			initial dma_state = `DMA_IDLE;
174			`initial o_interrupt = 1'b0;`
175			`initial cfg_len = {(AW){1'b0}};`
176			`initial cfg_blocklen_sub_one = {(LGMEMLEN){1'b1}};`
177			`initial cfg_on_dev_trigger = 1'b0;`
178			`initial cfg_len_nonzero = 1'b0;`
179			`always @(posedge i_clk)`
180			`case(dma_state)`
181			`DMA_IDLE: begin
182			`o_mwb_addr <= cfg_raddr;`
183			`nwritten <= 0;`
184			`nread <= 0;`
185			`nracks <= 0;`
186			`nwacks <= 0;`
187			`cfg_len_nonzero <= (\|cfg_len);`
188
189			`// When the slave wishbone writes, and we are in this`
190			`// (ready) configuration, then allow the DMA to be controlled`
191			`// and thus to start.`
192	32	dgisselq	`if ((i_swb_stb)&&(i_swb_we))`
193	3	dgisselq	`begin`
194			`case(i_swb_addr)`
195			`2'b00: begin`
196			`if ((i_swb_data[27:16] == 12'hfed)`
197			`&&(cfg_len_nonzero))`
198			dma_state <= `DMA_WAIT;
199			`cfg_blocklen_sub_one`
200			`<= i_swb_data[(LGMEMLEN-1):0]`
201			`+ {(LGMEMLEN){1'b1}};`
202			`// i.e. -1;`
203			`cfg_dev_trigger <= i_swb_data[14:10];`
204			`cfg_on_dev_trigger <= i_swb_data[15];`
205			`cfg_incs <= ~i_swb_data[29];`
206			`cfg_incd <= ~i_swb_data[28];`
207			`end`
208			`2'b01: begin`
209			`cfg_len <= i_swb_data[(AW-1):0];`
210			`cfg_len_nonzero <= (\|i_swb_data[(AW-1):0]);`
211			`end`
212			`2'b10: cfg_raddr <= i_swb_data[(AW-1):0];`
213			`2'b11: cfg_waddr <= i_swb_data[(AW-1):0];`
214			`endcase`
215			`end end`
216			`DMA_WAIT: begin
217			`o_mwb_addr <= cfg_raddr;`
218			`nracks <= 0;`
219			`nwacks <= 0;`
220			`nwritten <= 0;`
221			`nread <= 0;`
222			`if (abort)`
223			dma_state <= `DMA_IDLE;
224			`else if (trigger)`
225			dma_state <= `DMA_READ_REQ;
226			`end`
227			`DMA_READ_REQ: begin
228			`nwritten <= 0;`
229
230			`if (~i_mwb_stall)`
231			`begin`
232			`// Number of read acknowledgements needed`
233			`nracks <= nracks+1;`
234			`if (last_read_request)`
235			`//((nracks == {1'b0, cfg_blocklen_sub_one})\|\|(bus_nracks == cfg_len-1))`
236			`// Wishbone interruptus`
237			dma_state <= `DMA_READ_ACK;
238			`if (cfg_incs)`
239			`o_mwb_addr <= o_mwb_addr`
240			`+ {{(AW-1){1'b0}},1'b1};`
241			`end`
242
243			`if (i_mwb_err)`
244			`begin`
245			`cfg_len <= 0;`
246			dma_state <= `DMA_IDLE;
247			`end`
248			`if (abort)`
249			dma_state <= `DMA_IDLE;
250			`if (i_mwb_ack)`
251			`begin`
252			`nread <= nread+1;`
253			`if (cfg_incs)`
254			`cfg_raddr <= cfg_raddr`
255			`+ {{(AW-1){1'b0}},1'b1};`
256			`end end`
257			`DMA_READ_ACK: begin
258			`nwritten <= 0;`
259
260			`if (i_mwb_err)`
261			`begin`
262			`cfg_len <= 0;`
263			dma_state <= `DMA_IDLE;
264			`end else if (i_mwb_ack)`
265			`begin`
266			`nread <= nread+1;`
267			`if (last_read_ack) // (nread+1 == nracks)`
268			dma_state <= `DMA_PRE_WRITE;
269			`if (cfg_incs)`
270			`cfg_raddr <= cfg_raddr`
271			`+ {{(AW-1){1'b0}},1'b1};`
272			`end`
273			`if (abort)`
274			dma_state <= `DMA_IDLE;
275			`end`
276			`DMA_PRE_WRITE: begin
277			`o_mwb_addr <= cfg_waddr;`
278			dma_state <= (abort)?`DMA_IDLE:`DMA_WRITE_REQ;
279			`end`
280			`DMA_WRITE_REQ: begin
281			`if (~i_mwb_stall)`
282			`begin`
283			`nwritten <= nwritten+1;`
284			`if (last_write_request) // (nwritten == nread-1)`
285			`// Wishbone interruptus`
286			dma_state <= `DMA_WRITE_ACK;
287			`if (cfg_incd)`
288			`begin`
289			`o_mwb_addr <= o_mwb_addr`
290			`+ {{(AW-1){1'b0}},1'b1};`
291			`cfg_waddr <= cfg_waddr`
292			`+ {{(AW-1){1'b0}},1'b1};`
293			`end`
294			`end`
295
296			`if (i_mwb_err)`
297			`begin`
298			`cfg_len <= 0;`
299			dma_state <= `DMA_IDLE;
300			`end`
301			`if (i_mwb_ack)`
302			`begin`
303			`nwacks <= nwacks+1;`
304			`cfg_len <= cfg_len +{(AW){1'b1}}; // -1`
305			`end`
306			`if (abort)`
307			dma_state <= `DMA_IDLE;
308			`end`
309			`DMA_WRITE_ACK: begin
310			`if (i_mwb_err)`
311			`begin`
312			`cfg_len <= 0;`
313			`nread <= 0;`
314			dma_state <= `DMA_IDLE;
315			`end else if (i_mwb_ack)`
316			`begin`
317			`nwacks <= nwacks+1;`
318			`cfg_len <= cfg_len +{(AW){1'b1}};//cfg_len -= 1;`
319			`if (last_write_ack) // (nwacks+1 == nwritten)`
320			`begin`
321			`nread <= 0;`
322			dma_state <= (cfg_len == 1)?`DMA_IDLE:`DMA_WAIT;
323			`end`
324			`end`
325
326			`if (abort)`
327			dma_state <= `DMA_IDLE;
328			`end`
329			`default:`
330			dma_state <= `DMA_IDLE;
331			`endcase`
332
333			`initial o_interrupt = 1'b0;`
334			`always @(posedge i_clk)`
335	36	dgisselq	o_interrupt <= ((dma_state == `DMA_WRITE_ACK)&&(i_mwb_ack)
336			`&&(last_write_ack)`
337			`&&(cfg_len == {{(AW-1){1'b0}},1'b1}))`
338			\|\|((dma_state != `DMA_IDLE)&&(i_mwb_err));
339	3	dgisselq
340			`initial cfg_err = 1'b0;`
341			`always @(posedge i_clk)`
342			if (dma_state == `DMA_IDLE)
343			`begin`
344	32	dgisselq	`if ((i_swb_stb)&&(i_swb_we)&&(i_swb_addr==2'b00))`
345	3	dgisselq	`cfg_err <= 1'b0;`
346			`end else if (((i_mwb_err)&&(o_mwb_cyc))\|\|(abort))`
347			`cfg_err <= 1'b1;`
348
349			`initial last_read_request = 1'b0;`
350			`always @(posedge i_clk)`
351			if ((dma_state == `DMA_WAIT)\|\|(dma_state == `DMA_READ_REQ))
352			`begin`
353			if ((~i_mwb_stall)&&(dma_state == `DMA_READ_REQ))
354			`begin`
355			`last_read_request <=`
356			`(nracks + 1 == { 1'b0, cfg_blocklen_sub_one})`
357			`\|\|(bus_nracks == cfg_len-2);`
358			`end else`
359			`last_read_request <=`
360			`(nracks== { 1'b0, cfg_blocklen_sub_one})`
361			`\|\|(bus_nracks == cfg_len-1);`
362			`end else`
363			`last_read_request <= 1'b0;`
364
365			`initial last_read_ack = 1'b0;`
366			`always @(posedge i_clk)`
367			if ((dma_state == `DMA_READ_REQ)\|\|(dma_state == `DMA_READ_ACK))
368			`begin`
369	32	dgisselq	`if ((i_mwb_ack)&&((~o_mwb_stb)\|\|(i_mwb_stall)))`
370	3	dgisselq	`last_read_ack <= (nread+2 == nracks);`
371			`else`
372			`last_read_ack <= (nread+1 == nracks);`
373			`end else`
374			`last_read_ack <= 1'b0;`
375
376			`initial last_write_request = 1'b0;`
377			`always @(posedge i_clk)`
378			if (dma_state == `DMA_PRE_WRITE)
379			`last_write_request <= (nread <= 1);`
380			else if (dma_state == `DMA_WRITE_REQ)
381			`begin`
382			`if (i_mwb_stall)`
383			`last_write_request <= (nwritten >= nread-1);`
384			`else`
385			`last_write_request <= (nwritten >= nread-2);`
386			`end else`
387			`last_write_request <= 1'b0;`
388
389			`initial last_write_ack = 1'b0;`
390			`always @(posedge i_clk)`
391			if((dma_state == `DMA_WRITE_REQ)\|\|(dma_state == `DMA_WRITE_ACK))
392			`begin`
393	32	dgisselq	`if ((i_mwb_ack)&&((~o_mwb_stb)\|\|(i_mwb_stall)))`
394	3	dgisselq	`last_write_ack <= (nwacks+2 == nwritten);`
395			`else`
396			`last_write_ack <= (nwacks+1 == nwritten);`
397			`end else`
398			`last_write_ack <= 1'b0;`
399
400			assign o_mwb_cyc = (dma_state == `DMA_READ_REQ)
401			\|\|(dma_state == `DMA_READ_ACK)
402			\|\|(dma_state == `DMA_WRITE_REQ)
403			\|\|(dma_state == `DMA_WRITE_ACK);
404
405			assign o_mwb_stb = (dma_state == `DMA_READ_REQ)
406			\|\|(dma_state == `DMA_WRITE_REQ);
407
408			assign o_mwb_we = (dma_state == `DMA_PRE_WRITE)
409			\|\|(dma_state == `DMA_WRITE_REQ)
410			\|\|(dma_state == `DMA_WRITE_ACK);
411
412			`//`
413			`// This is tricky. In order for Vivado to consider dma_mem to be a`
414			`// proper memory, it must have a simple address fed into it. Hence`
415			`// the read_address (rdaddr) register. The problem is that this`
416			`// register must always be one greater than the address we actually`
417			`// want to read from, unless we are idling. So ... the math is touchy.`
418			`//`
419			`reg [(LGMEMLEN-1):0] rdaddr;`
420			`always @(posedge i_clk)`
421			if((dma_state == `DMA_IDLE)\|\|(dma_state == `DMA_WAIT)
422			\|\|(dma_state == `DMA_WRITE_ACK))
423			`rdaddr <= 0;`
424			else if ((dma_state == `DMA_PRE_WRITE)
425			\|\|((dma_state==`DMA_WRITE_REQ)&&(~i_mwb_stall)))
426			`rdaddr <= rdaddr + {{(LGMEMLEN-1){1'b0}},1'b1};`
427			`always @(posedge i_clk)`
428			if ((dma_state != `DMA_WRITE_REQ)\|\|(~i_mwb_stall))
429			`o_mwb_data <= dma_mem[rdaddr];`
430			`always @(posedge i_clk)`
431			if((dma_state == `DMA_READ_REQ)\|\|(dma_state == `DMA_READ_ACK))
432			`dma_mem[nread[(LGMEMLEN-1):0]] <= i_mwb_data;`
433
434			`always @(posedge i_clk)`
435			`casez(i_swb_addr)`
436			2'b00: o_swb_data <= { (dma_state != `DMA_IDLE), cfg_err,
437			`~cfg_incs, ~cfg_incd,`
438			`1'b0, nread,`
439			`cfg_on_dev_trigger, cfg_dev_trigger,`
440			`cfg_blocklen_sub_one`
441			`};`
442			`2'b01: o_swb_data <= { {(DW-AW){1'b0}}, cfg_len };`
443			`2'b10: o_swb_data <= { {(DW-AW){1'b0}}, cfg_raddr};`
444			`2'b11: o_swb_data <= { {(DW-AW){1'b0}}, cfg_waddr};`
445			`endcase`
446
447			`// This causes us to wait a minimum of two clocks before starting: One`
448			`// to go into the wait state, and then one while in the wait state to`
449			`// develop the trigger.`
450			`initial trigger = 1'b0;`
451			`always @(posedge i_clk)`
452			trigger <= (dma_state == `DMA_WAIT)
453			`&&((~cfg_on_dev_trigger)`
454			`\|\|(i_dev_ints[cfg_dev_trigger]));`
455
456			`// Ack any access. We'll quietly ignore any access where we are busy,`
457			`// but ack it anyway. In other words, before writing to the device,`
458			`// double check that it isn't busy, and then write.`
459			`always @(posedge i_clk)`
460	32	dgisselq	`o_swb_ack <= (i_swb_stb);`
461	3	dgisselq
462			`assign o_swb_stall = 1'b0;`
463
464			`initial abort = 1'b0;`
465			`always @(posedge i_clk)`
466	32	dgisselq	`abort <= (i_rst)\|\|((i_swb_stb)&&(i_swb_we)`
467	3	dgisselq	`&&(i_swb_addr == 2'b00)`
468			`&&(i_swb_data == 32'hffed0000));`
469
470			`endmodule`
471

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