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Encapsulated ahbinterface.
This commit is contained in:
Ross Thompson 2022-08-31 14:45:01 -05:00
parent fcd1465de1
commit 6e85f850a4
5 changed files with 415 additions and 9 deletions
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163
pipelined/src/ebu/AHBBuscachefsm.sv Normal file
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///////////////////////////////////////////
// busfsm.sv
//
// Written: Ross Thompson ross1728@gmail.com December 29, 2021
// Modified:
//
// Purpose: Load/Store Unit's interface to BUS for cacheless system
//
// A component of the Wally configurable RISC-V project.
//
// Copyright (C) 2021 Harvey Mudd College & Oklahoma State University
//
// MIT LICENSE
// Permission is hereby granted, free of charge, to any person obtaining a copy of this
// software and associated documentation files (the "Software"), to deal in the Software
// without restriction, including without limitation the rights to use, copy, modify, merge,
// publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons
// to whom the Software is furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in all copies or
// substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
// INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
// PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
// BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
// TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE
// OR OTHER DEALINGS IN THE SOFTWARE.
////////////////////////////////////////////////////////////////////////////////////////////////
`include "wally-config.vh"
// HCLK and clk must be the same clock!
module AHBBuscachefsm #(parameter integer WordCountThreshold,
parameter integer LOGWPL, parameter logic CACHE_ENABLED )
(input logic HCLK,
input logic HRESETn,
// IEU interface
input logic [1:0] RW,
input logic CPUBusy,
output logic BusCommitted,
output logic BusStall,
output logic CaptureEn,
// cache interface
input logic [1:0] CacheRW,
output logic CacheBusAck,
// lsu interface
output logic SelUncachedAdr,
output logic [LOGWPL-1:0] WordCount, WordCountDelayed,
output logic SelBusWord,
// BUS interface
input logic HREADY,
output logic [1:0] HTRANS,
output logic HWRITE,
output logic [2:0] HBURST
);
typedef enum logic [2:0] {STATE_READY,
STATE_CAPTURE,
STATE_DELAY,
STATE_CPU_BUSY,
STATE_CACHE_FETCH,
STATE_CACHE_EVICT} busstatetype;
typedef enum logic [1:0] {AHB_IDLE = 2'b00, AHB_BUSY = 2'b01, AHB_NONSEQ = 2'b10, AHB_SEQ = 2'b11} ahbtranstype;
(* mark_debug = "true" *) busstatetype BusCurrState, BusNextState;
logic [LOGWPL-1:0] NextWordCount;
logic FinalWordCount;
logic [2:0] LocalBurstType;
logic WordCntEn;
logic WordCntReset;
logic CacheAccess;
always_ff @(posedge HCLK)
if (~HRESETn) BusCurrState <= #1 STATE_READY;
else BusCurrState <= #1 BusNextState;
always_comb begin
case(BusCurrState)
STATE_READY: if(HREADY & |RW) BusNextState = STATE_CAPTURE;
else if (HREADY & CacheRW[0]) BusNextState = STATE_CACHE_EVICT;
else if (HREADY & CacheRW[1]) BusNextState = STATE_CACHE_FETCH;
else BusNextState = STATE_READY;
STATE_CAPTURE: if(HREADY) BusNextState = STATE_DELAY;
else BusNextState = STATE_CAPTURE;
STATE_DELAY: if(CPUBusy) BusNextState = STATE_CPU_BUSY;
else BusNextState = STATE_READY;
STATE_CPU_BUSY: if(CPUBusy) BusNextState = STATE_CPU_BUSY;
else BusNextState = STATE_READY;
STATE_CACHE_FETCH: if(HREADY & FinalWordCount) BusNextState = STATE_READY;
else BusNextState = STATE_CACHE_FETCH;
STATE_CACHE_EVICT: if(HREADY & FinalWordCount) BusNextState = STATE_READY;
else BusNextState = STATE_CACHE_EVICT;
default: BusNextState = STATE_READY;
endcase
end
// IEU, LSU, and IFU controls
flopenr #(LOGWPL)
WordCountReg(.clk(HCLK),
.reset(~HRESETn | WordCntReset),
.en(WordCntEn),
.d(NextWordCount),
.q(WordCount));
// Used to store data from data phase of AHB.
flopenr #(LOGWPL)
WordCountDelayedReg(.clk(HCLK),
.reset(~HRESETn | WordCntReset),
.en(WordCntEn),
.d(WordCount),
.q(WordCountDelayed));
assign NextWordCount = WordCount + 1'b1;
assign FinalWordCount = WordCountDelayed == WordCountThreshold[LOGWPL-1:0];
assign WordCntEn = ((BusNextState == STATE_CACHE_EVICT | BusNextState == STATE_CACHE_FETCH) & HREADY) |
(BusNextState == STATE_READY & |CacheRW & HREADY);
assign WordCntReset = BusNextState == STATE_READY;
assign CaptureEn = (BusCurrState == STATE_CAPTURE & RW[1]) | (BusCurrState == STATE_CACHE_FETCH & HREADY);
assign CacheAccess = BusCurrState == STATE_CACHE_FETCH | BusCurrState == STATE_CACHE_EVICT;
assign BusStall = (BusCurrState == STATE_READY & (|RW | |CacheRW)) |
(BusCurrState == STATE_CAPTURE) |
(BusCurrState == STATE_CACHE_FETCH) |
(BusCurrState == STATE_CACHE_EVICT);
assign BusCommitted = BusCurrState != STATE_READY;
assign SelUncachedAdr = (BusCurrState == STATE_READY & |RW) |
(BusCurrState == STATE_CAPTURE) |
(BusCurrState == STATE_DELAY);
// AHB bus interface
assign HTRANS = (BusCurrState == STATE_READY & HREADY & (|RW | |CacheRW)) |
(BusCurrState == STATE_CAPTURE & ~HREADY) |
(CacheAccess & ~HREADY & ~|WordCount) ? AHB_NONSEQ :
(CacheAccess & |WordCount) ? AHB_SEQ : AHB_IDLE;
assign HWRITE = RW[0] | CacheRW[0];
assign HBURST = (|CacheRW) ? LocalBurstType : 3'b0;
always_comb begin
case(WordCountThreshold)
0: LocalBurstType = 3'b000;
3: LocalBurstType = 3'b011; // INCR4
7: LocalBurstType = 3'b101; // INCR8
15: LocalBurstType = 3'b111; // INCR16
default: LocalBurstType = 3'b001; // INCR without end.
endcase
end
// communication to cache
assign CacheBusAck = (CacheAccess & HREADY & FinalWordCount);
assign SelBusWord = (BusCurrState == STATE_READY & (RW[0] | CacheRW[0])) |
(BusCurrState == STATE_CAPTURE & RW[0]) |
(BusCurrState == STATE_CACHE_EVICT);
endmodule

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pipelined/src/ebu/AHBBusfsm.sv Normal file
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///////////////////////////////////////////
// busfsm.sv
//
// Written: Ross Thompson ross1728@gmail.com December 29, 2021
// Modified:
//
// Purpose: Load/Store Unit's interface to BUS for cacheless system
//
// A component of the Wally configurable RISC-V project.
//
// Copyright (C) 2021 Harvey Mudd College & Oklahoma State University
//
// MIT LICENSE
// Permission is hereby granted, free of charge, to any person obtaining a copy of this
// software and associated documentation files (the "Software"), to deal in the Software
// without restriction, including without limitation the rights to use, copy, modify, merge,
// publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons
// to whom the Software is furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in all copies or
// substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
// INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
// PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
// BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
// TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE
// OR OTHER DEALINGS IN THE SOFTWARE.
////////////////////////////////////////////////////////////////////////////////////////////////
`include "wally-config.vh"
// HCLK and clk must be the same clock!
module AHBBusfsm
(input logic HCLK,
input logic HRESETn,
// IEU interface
input logic [1:0] RW,
input logic CPUBusy,
output logic BusCommitted,
output logic BusStall,
output logic CaptureEn,
input logic HREADY,
output logic [1:0] HTRANS,
output logic HWRITE
);
typedef enum logic [2:0] {STATE_READY,
STATE_CAPTURE,
STATE_DELAY,
STATE_CPU_BUSY} busstatetype;
typedef enum logic [1:0] {AHB_IDLE = 2'b00, AHB_BUSY = 2'b01, AHB_NONSEQ = 2'b10, AHB_SEQ = 2'b11} ahbtranstype;
(* mark_debug = "true" *) busstatetype BusCurrState, BusNextState;
always_ff @(posedge HCLK)
if (~HRESETn) BusCurrState <= #1 STATE_READY;
else BusCurrState <= #1 BusNextState;
always_comb begin
case(BusCurrState)
STATE_READY: if(HREADY & |RW) BusNextState = STATE_CAPTURE;
else BusNextState = STATE_READY;
STATE_CAPTURE: if(HREADY) BusNextState = STATE_DELAY;
else BusNextState = STATE_CAPTURE;
STATE_DELAY: if(CPUBusy) BusNextState = STATE_CPU_BUSY;
else BusNextState = STATE_READY;
STATE_CPU_BUSY: if(CPUBusy) BusNextState = STATE_CPU_BUSY;
else BusNextState = STATE_READY;
default: BusNextState = STATE_READY;
endcase
end
assign BusStall = (BusCurrState == STATE_READY & |RW) |
(BusCurrState == STATE_CAPTURE);
assign BusCommitted = BusCurrState != STATE_READY;
assign HTRANS = (BusCurrState == STATE_READY & HREADY & |RW) |
(BusCurrState == STATE_CAPTURE & ~HREADY) ? AHB_NONSEQ : AHB_IDLE;
assign HWRITE = (BusCurrState == STATE_READY) & RW[0]; // *** might not be necessary, maybe just RW[0]
assign CaptureEn = BusCurrState == STATE_CAPTURE;
endmodule

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///////////////////////////////////////////
// ahbinterface.sv
//
// Written: Ross Thompson ross1728@gmail.com August 29, 2022
// Modified:
//
// Purpose: Cache/Bus data path.
// Bus Side logic
// register the fetch data from the next level of memory.
// This register should be necessary for timing. There is no register in the uncore or
// ahblite controller between the memories and this cache.
//
// A component of the Wally configurable RISC-V project.
//
// Copyright (C) 2021 Harvey Mudd College & Oklahoma State University
//
// MIT LICENSE
// Permission is hereby granted, free of charge, to any person obtaining a copy of this
// software and associated documentation files (the "Software"), to deal in the Software
// without restriction, including without limitation the rights to use, copy, modify, merge,
// publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons
// to whom the Software is furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in all copies or
// substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
// INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
// PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
// BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
// TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE
// OR OTHER DEALINGS IN THE SOFTWARE.
////////////////////////////////////////////////////////////////////////////////////////////////
`include "wally-config.vh"
module ahbinterface #(parameter WRITEABLE = 0)
(
input logic HCLK, HRESETn,
// bus interface
input logic HREADY,
input logic [`XLEN-1:0] HRDATA,
output logic [1:0] HTRANS,
output logic HWRITE,
output logic [`XLEN-1:0] HWDATA,
output logic [`XLEN/8-1:0] HWSTRB,
// lsu/ifu interface
input logic [1:0] RW,
input logic [`XLEN/8-1:0] ByteMask,
input logic [`XLEN-1:0] WriteData,
input logic CPUBusy,
output logic BusStall,
output logic BusCommitted,
output logic [`XLEN-1:0] ReadDataWordM);
logic CaptureEn;
flopen #(`XLEN) fb(.clk(HCLK), .en(CaptureEn), .d(HRDATA), .q(ReadDataWordM));
if(WRITEABLE) begin
// delay HWDATA by 1 cycle per spec; *** assumes AHBW = XLEN
flop #(`XLEN) wdreg(HCLK, WriteData, HWDATA);
flop #(`XLEN/8) HWSTRBReg(HCLK, ByteMask, HWSTRB);
end else begin
assign HWDATA = '0;
assign HWSTRB = '0;
end
AHBBusfsm busfsm(.HCLK, .HRESETn, .RW,
.BusCommitted, .CPUBusy, .BusStall, .CaptureEn, .HREADY,
.HTRANS, .HWRITE);
endmodule

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pipelined/src/ebu/ahbcacheinterface.sv Normal file
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///////////////////////////////////////////
// ahbcacheinterface.sv
//
// Written: Ross Thompson ross1728@gmail.com August 29, 2022
// Modified:
//
// Purpose: Cache/Bus data path.
// Bus Side logic
// register the fetch data from the next level of memory.
// This register should be necessary for timing. There is no register in the uncore or
// ahblite controller between the memories and this cache.
//
// A component of the Wally configurable RISC-V project.
//
// Copyright (C) 2021 Harvey Mudd College & Oklahoma State University
//
// MIT LICENSE
// Permission is hereby granted, free of charge, to any person obtaining a copy of this
// software and associated documentation files (the "Software"), to deal in the Software
// without restriction, including without limitation the rights to use, copy, modify, merge,
// publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons
// to whom the Software is furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in all copies or
// substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
// INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
// PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
// BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
// TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE
// OR OTHER DEALINGS IN THE SOFTWARE.
////////////////////////////////////////////////////////////////////////////////////////////////
`include "wally-config.vh"
module ahbcacheinterface #(parameter WORDSPERLINE, LINELEN, LOGWPL, CACHE_ENABLED)
(
input logic HCLK, HRESETn,
// bus interface
input logic HREADY,
input logic [`XLEN-1:0] HRDATA,
output logic [2:0] HSIZE,
output logic [2:0] HBURST,
output logic [1:0] HTRANS,
output logic HWRITE,
output logic [`PA_BITS-1:0] HADDR,
output logic [LOGWPL-1:0] WordCount,
// cache interface
input logic [`PA_BITS-1:0] CacheBusAdr,
input logic [1:0] CacheRW,
output logic CacheBusAck,
output logic [LINELEN-1:0] FetchBuffer,
output logic SelUncachedAdr,
// lsu/ifu interface
input logic [`PA_BITS-1:0] PAdr,
input logic [1:0] RW,
input logic CPUBusy,
input logic [2:0] Funct3,
output logic SelBusWord,
output logic BusStall,
output logic BusCommitted);
localparam integer WordCountThreshold = CACHE_ENABLED ? WORDSPERLINE - 1 : 0;
logic [`PA_BITS-1:0] LocalHADDR;
logic [LOGWPL-1:0] WordCountDelayed;
logic CaptureEn;
genvar index;
for (index = 0; index < WORDSPERLINE; index++) begin:fetchbuffer
logic [WORDSPERLINE-1:0] CaptureWord;
assign CaptureWord[index] = CaptureEn & (index == WordCountDelayed);
flopen #(`XLEN) fb(.clk(HCLK), .en(CaptureWord[index]), .d(HRDATA),
.q(FetchBuffer[(index+1)*`XLEN-1:index*`XLEN]));
end
mux2 #(`PA_BITS) localadrmux(CacheBusAdr, PAdr, SelUncachedAdr, LocalHADDR);
assign HADDR = ({{`PA_BITS-LOGWPL{1'b0}}, WordCount} << $clog2(`XLEN/8)) + LocalHADDR;
mux2 #(3) sizemux(.d0(`XLEN == 32 ? 3'b010 : 3'b011), .d1(Funct3), .s(SelUncachedAdr), .y(HSIZE));
AHBBuscachefsm #(WordCountThreshold, LOGWPL, CACHE_ENABLED) AHBBuscachefsm(
.HCLK, .HRESETn, .RW, .CPUBusy, .BusCommitted, .BusStall, .CaptureEn, .SelBusWord,
.CacheRW, .CacheBusAck, .SelUncachedAdr, .WordCount, .WordCountDelayed,
.HREADY, .HTRANS, .HWRITE, .HBURST);
endmodule

12
pipelined/src/lsu/lsu.sv
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@ -282,7 +282,6 @@ module lsu (
swbytemask #(`XLEN) busswbytemask(.Size(LSUHSIZE), .Adr(LSUPAdrM[$clog2(`XLEN/8)-1:0]), .ByteMask(BusByteMaskM));
flop #(`XLEN/8) HWSTRBReg(clk, BusByteMaskM[`XLEN/8-1:0], LSUHWSTRB);
end else begin : passthrough // just needs a register to hold the value from the bus
logic CaptureEn;
@ -291,15 +290,10 @@ module lsu (
assign LSUHADDR = LSUPAdrM;
assign LSUHSIZE = LSUFunct3M;
flopen #(`XLEN) fb(.clk, .en(CaptureEn), .d(HRDATA), .q(ReadDataWordM));
flop #(`XLEN) wdreg(clk, LSUWriteDataM, LSUHWDATA); // delay HWDATA by 1 cycle per spec; *** assumes AHBW = XLEN
flop #(`XLEN/8) HWSTRBReg(clk, ByteMaskM, LSUHWSTRB);
AHBBusfsm busfsm(.HCLK(clk), .HRESETn(~reset), .RW,
.BusCommitted(BusCommittedM), .CPUBusy, .BusStall, .CaptureEn, .HREADY(LSUHREADY), .HTRANS(LSUHTRANS),
.HWRITE(LSUHWRITE));
ahbinterface #(1) ahbinterface(.HCLK(clk), .HRESETn(~reset), .HREADY(LSUHREADY),
.HRDATA(HRDATA), .HTRANS(LSUHTRANS), .HWRITE(LSUHWRITE), .HWDATA(LSUHWDATA),
.HWSTRB(LSUHWSTRB), .RW, .ByteMask(ByteMaskM), .WriteData(LSUWriteDataM), .CPUBusy, .BusStall, .BusCommitted(BusCommittedM), .ReadDataWordM);
assign ReadDataWordMuxM = LittleEndianReadDataWordM; // from byte swapping
assign LSUHBURST = 3'b0;