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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 Technology, LLC
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//
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////////////////////////////////////////////////////////////////////////////////
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//
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// Copyright (C) 2015-2016, 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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`define DMA_IDLE 3'b000
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`define DMA_WAIT 3'b001
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`define DMA_READ_REQ 3'b010
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`define DMA_READ_ACK 3'b011
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`define DMA_PRE_WRITE 3'b100
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`define DMA_WRITE_REQ 3'b101
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`define DMA_WRITE_ACK 3'b110
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module wbdmac(i_clk, i_rst,
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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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parameter ADDRESS_WIDTH=32, LGMEMLEN = 10,
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DW=32, LGDV=5,AW=ADDRESS_WIDTH;
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input i_clk, i_rst;
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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 wire o_mwb_cyc, o_mwb_stb, o_mwb_we;
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output reg [(AW-1):0] o_mwb_addr;
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output reg [(DW-1):0] 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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// This logic had lots of problems, so it is being
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// removed. If you want to make sure the bus is available
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// for a higher priority user, adjust the transfer length
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// accordingly.
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//
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// input i_other_busmaster_requests_bus;
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//
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reg [2:0] dma_state;
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reg cfg_err, cfg_len_nonzero;
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reg [(AW-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, nwacks, nracks;
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wire [(AW-1):0] bus_nracks;
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assign bus_nracks = { {(AW-LGMEMLEN-1){1'b0}}, nracks };
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reg last_read_request, last_read_ack,
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last_write_request, last_write_ack;
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reg trigger, abort;
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initial dma_state = `DMA_IDLE;
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initial o_interrupt = 1'b0;
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initial cfg_len = {(AW){1'b0}};
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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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initial cfg_len_nonzero = 1'b0;
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always @(posedge i_clk)
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case(dma_state)
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`DMA_IDLE: begin
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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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nracks <= 0;
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nwacks <= 0;
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cfg_len_nonzero <= (|cfg_len);
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// When the slave wishbone writes, and we are in this
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// (ready) configuration, then allow the DMA to be controlled
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// and thus to start.
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32 |
dgisselq |
if ((i_swb_stb)&&(i_swb_we))
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3 |
dgisselq |
begin
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case(i_swb_addr)
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2'b00: begin
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if ((i_swb_data[27:16] == 12'hfed)
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&&(cfg_len_nonzero))
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dma_state <= `DMA_WAIT;
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cfg_blocklen_sub_one
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<= i_swb_data[(LGMEMLEN-1):0]
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+ {(LGMEMLEN){1'b1}};
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// i.e. -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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end
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2'b01: begin
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cfg_len <= i_swb_data[(AW-1):0];
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cfg_len_nonzero <= (|i_swb_data[(AW-1):0]);
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end
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2'b10: cfg_raddr <= i_swb_data[(AW-1):0];
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2'b11: cfg_waddr <= i_swb_data[(AW-1):0];
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endcase
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end end
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`DMA_WAIT: begin
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o_mwb_addr <= cfg_raddr;
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nracks <= 0;
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nwacks <= 0;
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nwritten <= 0;
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nread <= 0;
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if (abort)
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dma_state <= `DMA_IDLE;
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else if (trigger)
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dma_state <= `DMA_READ_REQ;
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end
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`DMA_READ_REQ: begin
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nwritten <= 0;
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if (~i_mwb_stall)
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begin
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// Number of read acknowledgements needed
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nracks <= nracks+1;
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if (last_read_request)
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//((nracks == {1'b0, cfg_blocklen_sub_one})||(bus_nracks == cfg_len-1))
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// Wishbone interruptus
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dma_state <= `DMA_READ_ACK;
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if (cfg_incs)
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o_mwb_addr <= o_mwb_addr
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+ {{(AW-1){1'b0}},1'b1};
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end
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if (i_mwb_err)
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begin
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cfg_len <= 0;
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dma_state <= `DMA_IDLE;
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end
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if (abort)
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dma_state <= `DMA_IDLE;
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if (i_mwb_ack)
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begin
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nread <= nread+1;
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if (cfg_incs)
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cfg_raddr <= cfg_raddr
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+ {{(AW-1){1'b0}},1'b1};
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end end
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`DMA_READ_ACK: begin
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nwritten <= 0;
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if (i_mwb_err)
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begin
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cfg_len <= 0;
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dma_state <= `DMA_IDLE;
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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 (last_read_ack) // (nread+1 == nracks)
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dma_state <= `DMA_PRE_WRITE;
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if (cfg_incs)
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cfg_raddr <= cfg_raddr
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+ {{(AW-1){1'b0}},1'b1};
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end
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if (abort)
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dma_state <= `DMA_IDLE;
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end
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`DMA_PRE_WRITE: begin
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o_mwb_addr <= cfg_waddr;
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dma_state <= (abort)?`DMA_IDLE:`DMA_WRITE_REQ;
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end
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`DMA_WRITE_REQ: begin
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if (~i_mwb_stall)
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begin
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nwritten <= nwritten+1;
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if (last_write_request) // (nwritten == nread-1)
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// Wishbone interruptus
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dma_state <= `DMA_WRITE_ACK;
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if (cfg_incd)
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begin
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o_mwb_addr <= o_mwb_addr
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+ {{(AW-1){1'b0}},1'b1};
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cfg_waddr <= cfg_waddr
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+ {{(AW-1){1'b0}},1'b1};
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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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cfg_len <= 0;
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dma_state <= `DMA_IDLE;
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end
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if (i_mwb_ack)
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begin
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nwacks <= nwacks+1;
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cfg_len <= cfg_len +{(AW){1'b1}}; // -1
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end
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if (abort)
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dma_state <= `DMA_IDLE;
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end
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`DMA_WRITE_ACK: begin
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if (i_mwb_err)
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begin
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cfg_len <= 0;
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nread <= 0;
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dma_state <= `DMA_IDLE;
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end else if (i_mwb_ack)
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begin
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nwacks <= nwacks+1;
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cfg_len <= cfg_len +{(AW){1'b1}};//cfg_len -= 1;
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if (last_write_ack) // (nwacks+1 == nwritten)
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begin
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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 |
|
|
o_interrupt <= (dma_state == `DMA_WRITE_ACK)&&(i_mwb_ack)
|
| 336 |
|
|
&&(last_write_ack)
|
| 337 |
|
|
&&(cfg_len == {{(AW-1){1'b0}},1'b1});
|
| 338 |
|
|
|
| 339 |
|
|
initial cfg_err = 1'b0;
|
| 340 |
|
|
always @(posedge i_clk)
|
| 341 |
|
|
if (dma_state == `DMA_IDLE)
|
| 342 |
|
|
begin
|
| 343 |
32 |
dgisselq |
if ((i_swb_stb)&&(i_swb_we)&&(i_swb_addr==2'b00))
|
| 344 |
3 |
dgisselq |
cfg_err <= 1'b0;
|
| 345 |
|
|
end else if (((i_mwb_err)&&(o_mwb_cyc))||(abort))
|
| 346 |
|
|
cfg_err <= 1'b1;
|
| 347 |
|
|
|
| 348 |
|
|
initial last_read_request = 1'b0;
|
| 349 |
|
|
always @(posedge i_clk)
|
| 350 |
|
|
if ((dma_state == `DMA_WAIT)||(dma_state == `DMA_READ_REQ))
|
| 351 |
|
|
begin
|
| 352 |
|
|
if ((~i_mwb_stall)&&(dma_state == `DMA_READ_REQ))
|
| 353 |
|
|
begin
|
| 354 |
|
|
last_read_request <=
|
| 355 |
|
|
(nracks + 1 == { 1'b0, cfg_blocklen_sub_one})
|
| 356 |
|
|
||(bus_nracks == cfg_len-2);
|
| 357 |
|
|
end else
|
| 358 |
|
|
last_read_request <=
|
| 359 |
|
|
(nracks== { 1'b0, cfg_blocklen_sub_one})
|
| 360 |
|
|
||(bus_nracks == cfg_len-1);
|
| 361 |
|
|
end else
|
| 362 |
|
|
last_read_request <= 1'b0;
|
| 363 |
|
|
|
| 364 |
|
|
initial last_read_ack = 1'b0;
|
| 365 |
|
|
always @(posedge i_clk)
|
| 366 |
|
|
if ((dma_state == `DMA_READ_REQ)||(dma_state == `DMA_READ_ACK))
|
| 367 |
|
|
begin
|
| 368 |
32 |
dgisselq |
if ((i_mwb_ack)&&((~o_mwb_stb)||(i_mwb_stall)))
|
| 369 |
3 |
dgisselq |
last_read_ack <= (nread+2 == nracks);
|
| 370 |
|
|
else
|
| 371 |
|
|
last_read_ack <= (nread+1 == nracks);
|
| 372 |
|
|
end else
|
| 373 |
|
|
last_read_ack <= 1'b0;
|
| 374 |
|
|
|
| 375 |
|
|
initial last_write_request = 1'b0;
|
| 376 |
|
|
always @(posedge i_clk)
|
| 377 |
|
|
if (dma_state == `DMA_PRE_WRITE)
|
| 378 |
|
|
last_write_request <= (nread <= 1);
|
| 379 |
|
|
else if (dma_state == `DMA_WRITE_REQ)
|
| 380 |
|
|
begin
|
| 381 |
|
|
if (i_mwb_stall)
|
| 382 |
|
|
last_write_request <= (nwritten >= nread-1);
|
| 383 |
|
|
else
|
| 384 |
|
|
last_write_request <= (nwritten >= nread-2);
|
| 385 |
|
|
end else
|
| 386 |
|
|
last_write_request <= 1'b0;
|
| 387 |
|
|
|
| 388 |
|
|
initial last_write_ack = 1'b0;
|
| 389 |
|
|
always @(posedge i_clk)
|
| 390 |
|
|
if((dma_state == `DMA_WRITE_REQ)||(dma_state == `DMA_WRITE_ACK))
|
| 391 |
|
|
begin
|
| 392 |
32 |
dgisselq |
if ((i_mwb_ack)&&((~o_mwb_stb)||(i_mwb_stall)))
|
| 393 |
3 |
dgisselq |
last_write_ack <= (nwacks+2 == nwritten);
|
| 394 |
|
|
else
|
| 395 |
|
|
last_write_ack <= (nwacks+1 == nwritten);
|
| 396 |
|
|
end else
|
| 397 |
|
|
last_write_ack <= 1'b0;
|
| 398 |
|
|
|
| 399 |
|
|
assign o_mwb_cyc = (dma_state == `DMA_READ_REQ)
|
| 400 |
|
|
||(dma_state == `DMA_READ_ACK)
|
| 401 |
|
|
||(dma_state == `DMA_WRITE_REQ)
|
| 402 |
|
|
||(dma_state == `DMA_WRITE_ACK);
|
| 403 |
|
|
|
| 404 |
|
|
assign o_mwb_stb = (dma_state == `DMA_READ_REQ)
|
| 405 |
|
|
||(dma_state == `DMA_WRITE_REQ);
|
| 406 |
|
|
|
| 407 |
|
|
assign o_mwb_we = (dma_state == `DMA_PRE_WRITE)
|
| 408 |
|
|
||(dma_state == `DMA_WRITE_REQ)
|
| 409 |
|
|
||(dma_state == `DMA_WRITE_ACK);
|
| 410 |
|
|
|
| 411 |
|
|
//
|
| 412 |
|
|
// This is tricky. In order for Vivado to consider dma_mem to be a
|
| 413 |
|
|
// proper memory, it must have a simple address fed into it. Hence
|
| 414 |
|
|
// the read_address (rdaddr) register. The problem is that this
|
| 415 |
|
|
// register must always be one greater than the address we actually
|
| 416 |
|
|
// want to read from, unless we are idling. So ... the math is touchy.
|
| 417 |
|
|
//
|
| 418 |
|
|
reg [(LGMEMLEN-1):0] rdaddr;
|
| 419 |
|
|
always @(posedge i_clk)
|
| 420 |
|
|
if((dma_state == `DMA_IDLE)||(dma_state == `DMA_WAIT)
|
| 421 |
|
|
||(dma_state == `DMA_WRITE_ACK))
|
| 422 |
|
|
rdaddr <= 0;
|
| 423 |
|
|
else if ((dma_state == `DMA_PRE_WRITE)
|
| 424 |
|
|
||((dma_state==`DMA_WRITE_REQ)&&(~i_mwb_stall)))
|
| 425 |
|
|
rdaddr <= rdaddr + {{(LGMEMLEN-1){1'b0}},1'b1};
|
| 426 |
|
|
always @(posedge i_clk)
|
| 427 |
|
|
if ((dma_state != `DMA_WRITE_REQ)||(~i_mwb_stall))
|
| 428 |
|
|
o_mwb_data <= dma_mem[rdaddr];
|
| 429 |
|
|
always @(posedge i_clk)
|
| 430 |
|
|
if((dma_state == `DMA_READ_REQ)||(dma_state == `DMA_READ_ACK))
|
| 431 |
|
|
dma_mem[nread[(LGMEMLEN-1):0]] <= i_mwb_data;
|
| 432 |
|
|
|
| 433 |
|
|
always @(posedge i_clk)
|
| 434 |
|
|
casez(i_swb_addr)
|
| 435 |
|
|
2'b00: o_swb_data <= { (dma_state != `DMA_IDLE), cfg_err,
|
| 436 |
|
|
~cfg_incs, ~cfg_incd,
|
| 437 |
|
|
1'b0, nread,
|
| 438 |
|
|
cfg_on_dev_trigger, cfg_dev_trigger,
|
| 439 |
|
|
cfg_blocklen_sub_one
|
| 440 |
|
|
};
|
| 441 |
|
|
2'b01: o_swb_data <= { {(DW-AW){1'b0}}, cfg_len };
|
| 442 |
|
|
2'b10: o_swb_data <= { {(DW-AW){1'b0}}, cfg_raddr};
|
| 443 |
|
|
2'b11: o_swb_data <= { {(DW-AW){1'b0}}, cfg_waddr};
|
| 444 |
|
|
endcase
|
| 445 |
|
|
|
| 446 |
|
|
// This causes us to wait a minimum of two clocks before starting: One
|
| 447 |
|
|
// to go into the wait state, and then one while in the wait state to
|
| 448 |
|
|
// develop the trigger.
|
| 449 |
|
|
initial trigger = 1'b0;
|
| 450 |
|
|
always @(posedge i_clk)
|
| 451 |
|
|
trigger <= (dma_state == `DMA_WAIT)
|
| 452 |
|
|
&&((~cfg_on_dev_trigger)
|
| 453 |
|
|
||(i_dev_ints[cfg_dev_trigger]));
|
| 454 |
|
|
|
| 455 |
|
|
// Ack any access. We'll quietly ignore any access where we are busy,
|
| 456 |
|
|
// but ack it anyway. In other words, before writing to the device,
|
| 457 |
|
|
// double check that it isn't busy, and then write.
|
| 458 |
|
|
always @(posedge i_clk)
|
| 459 |
32 |
dgisselq |
o_swb_ack <= (i_swb_stb);
|
| 460 |
3 |
dgisselq |
|
| 461 |
|
|
assign o_swb_stall = 1'b0;
|
| 462 |
|
|
|
| 463 |
|
|
initial abort = 1'b0;
|
| 464 |
|
|
always @(posedge i_clk)
|
| 465 |
32 |
dgisselq |
abort <= (i_rst)||((i_swb_stb)&&(i_swb_we)
|
| 466 |
3 |
dgisselq |
&&(i_swb_addr == 2'b00)
|
| 467 |
|
|
&&(i_swb_data == 32'hffed0000));
|
| 468 |
|
|
|
| 469 |
|
|
endmodule
|
| 470 |
|
|
|
