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yosys/tests/openmsp430/rtl/omsp_mem_backbone.v

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//----------------------------------------------------------------------------
// Copyright (C) 2009 , Olivier Girard
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions
// are met:
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above copyright
// notice, this list of conditions and the following disclaimer in the
// documentation and/or other materials provided with the distribution.
// * Neither the name of the authors nor the names of its contributors
// may be used to endorse or promote products derived from this software
// without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
// ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY,
// OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
// SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
// CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
// THE POSSIBILITY OF SUCH DAMAGE
//
//----------------------------------------------------------------------------
//
// *File Name: omsp_mem_backbone.v
//
// *Module Description:
// Memory interface backbone (decoder + arbiter)
//
// *Author(s):
// - Olivier Girard, olgirard@gmail.com
//
//----------------------------------------------------------------------------
// $Rev: 151 $
// $LastChangedBy: olivier.girard $
// $LastChangedDate: 2012-07-23 00:24:11 +0200 (Mon, 23 Jul 2012) $
//----------------------------------------------------------------------------
`ifdef OMSP_NO_INCLUDE
`else
`include "openMSP430_defines.v"
`endif
module omsp_mem_backbone (
// OUTPUTs
dbg_mem_din, // Debug unit Memory data input
dmem_addr, // Data Memory address
dmem_cen, // Data Memory chip enable (low active)
dmem_din, // Data Memory data input
dmem_wen, // Data Memory write enable (low active)
eu_mdb_in, // Execution Unit Memory data bus input
fe_mdb_in, // Frontend Memory data bus input
fe_pmem_wait, // Frontend wait for Instruction fetch
per_addr, // Peripheral address
per_din, // Peripheral data input
per_we, // Peripheral write enable (high active)
per_en, // Peripheral enable (high active)
pmem_addr, // Program Memory address
pmem_cen, // Program Memory chip enable (low active)
pmem_din, // Program Memory data input (optional)
pmem_wen, // Program Memory write enable (low active) (optional)
// INPUTs
dbg_halt_st, // Halt/Run status from CPU
dbg_mem_addr, // Debug address for rd/wr access
dbg_mem_dout, // Debug unit data output
dbg_mem_en, // Debug unit memory enable
dbg_mem_wr, // Debug unit memory write
dmem_dout, // Data Memory data output
eu_mab, // Execution Unit Memory address bus
eu_mb_en, // Execution Unit Memory bus enable
eu_mb_wr, // Execution Unit Memory bus write transfer
eu_mdb_out, // Execution Unit Memory data bus output
fe_mab, // Frontend Memory address bus
fe_mb_en, // Frontend Memory bus enable
mclk, // Main system clock
per_dout, // Peripheral data output
pmem_dout, // Program Memory data output
puc_rst, // Main system reset
scan_enable // Scan enable (active during scan shifting)
);
// OUTPUTs
//=========
output [15:0] dbg_mem_din; // Debug unit Memory data input
output [`DMEM_MSB:0] dmem_addr; // Data Memory address
output dmem_cen; // Data Memory chip enable (low active)
output [15:0] dmem_din; // Data Memory data input
output [1:0] dmem_wen; // Data Memory write enable (low active)
output [15:0] eu_mdb_in; // Execution Unit Memory data bus input
output [15:0] fe_mdb_in; // Frontend Memory data bus input
output fe_pmem_wait; // Frontend wait for Instruction fetch
output [13:0] per_addr; // Peripheral address
output [15:0] per_din; // Peripheral data input
output [1:0] per_we; // Peripheral write enable (high active)
output per_en; // Peripheral enable (high active)
output [`PMEM_MSB:0] pmem_addr; // Program Memory address
output pmem_cen; // Program Memory chip enable (low active)
output [15:0] pmem_din; // Program Memory data input (optional)
output [1:0] pmem_wen; // Program Memory write enable (low active) (optional)
// INPUTs
//=========
input dbg_halt_st; // Halt/Run status from CPU
input [15:0] dbg_mem_addr; // Debug address for rd/wr access
input [15:0] dbg_mem_dout; // Debug unit data output
input dbg_mem_en; // Debug unit memory enable
input [1:0] dbg_mem_wr; // Debug unit memory write
input [15:0] dmem_dout; // Data Memory data output
input [14:0] eu_mab; // Execution Unit Memory address bus
input eu_mb_en; // Execution Unit Memory bus enable
input [1:0] eu_mb_wr; // Execution Unit Memory bus write transfer
input [15:0] eu_mdb_out; // Execution Unit Memory data bus output
input [14:0] fe_mab; // Frontend Memory address bus
input fe_mb_en; // Frontend Memory bus enable
input mclk; // Main system clock
input [15:0] per_dout; // Peripheral data output
input [15:0] pmem_dout; // Program Memory data output
input puc_rst; // Main system reset
input scan_enable; // Scan enable (active during scan shifting)
//=============================================================================
// 1) DECODER
//=============================================================================
// RAM Interface
//------------------
// Execution unit access
wire eu_dmem_cen = ~(eu_mb_en & (eu_mab>=(`DMEM_BASE>>1)) &
(eu_mab<((`DMEM_BASE+`DMEM_SIZE)>>1)));
wire [15:0] eu_dmem_addr = {1'b0, eu_mab}-(`DMEM_BASE>>1);
// Debug interface access
wire dbg_dmem_cen = ~(dbg_mem_en & (dbg_mem_addr[15:1]>=(`DMEM_BASE>>1)) &
(dbg_mem_addr[15:1]<((`DMEM_BASE+`DMEM_SIZE)>>1)));
wire [15:0] dbg_dmem_addr = {1'b0, dbg_mem_addr[15:1]}-(`DMEM_BASE>>1);
// RAM Interface
wire [`DMEM_MSB:0] dmem_addr = ~dbg_dmem_cen ? dbg_dmem_addr[`DMEM_MSB:0] : eu_dmem_addr[`DMEM_MSB:0];
wire dmem_cen = dbg_dmem_cen & eu_dmem_cen;
wire [1:0] dmem_wen = ~(dbg_mem_wr | eu_mb_wr);
wire [15:0] dmem_din = ~dbg_dmem_cen ? dbg_mem_dout : eu_mdb_out;
// ROM Interface
//------------------
parameter PMEM_OFFSET = (16'hFFFF-`PMEM_SIZE+1);
// Execution unit access (only read access are accepted)
wire eu_pmem_cen = ~(eu_mb_en & ~|eu_mb_wr & (eu_mab>=(PMEM_OFFSET>>1)));
wire [15:0] eu_pmem_addr = eu_mab-(PMEM_OFFSET>>1);
// Front-end access
wire fe_pmem_cen = ~(fe_mb_en & (fe_mab>=(PMEM_OFFSET>>1)));
wire [15:0] fe_pmem_addr = fe_mab-(PMEM_OFFSET>>1);
// Debug interface access
wire dbg_pmem_cen = ~(dbg_mem_en & (dbg_mem_addr[15:1]>=(PMEM_OFFSET>>1)));
wire [15:0] dbg_pmem_addr = {1'b0, dbg_mem_addr[15:1]}-(PMEM_OFFSET>>1);
// ROM Interface (Execution unit has priority)
wire [`PMEM_MSB:0] pmem_addr = ~dbg_pmem_cen ? dbg_pmem_addr[`PMEM_MSB:0] :
~eu_pmem_cen ? eu_pmem_addr[`PMEM_MSB:0] : fe_pmem_addr[`PMEM_MSB:0];
wire pmem_cen = fe_pmem_cen & eu_pmem_cen & dbg_pmem_cen;
wire [1:0] pmem_wen = ~dbg_mem_wr;
wire [15:0] pmem_din = dbg_mem_dout;
wire fe_pmem_wait = (~fe_pmem_cen & ~eu_pmem_cen);
// Peripherals
//--------------------
wire dbg_per_en = dbg_mem_en & (dbg_mem_addr[15:1]<(`PER_SIZE>>1));
wire eu_per_en = eu_mb_en & (eu_mab<(`PER_SIZE>>1));
wire [15:0] per_din = dbg_mem_en ? dbg_mem_dout : eu_mdb_out;
wire [1:0] per_we = dbg_mem_en ? dbg_mem_wr : eu_mb_wr;
wire per_en = dbg_mem_en ? dbg_per_en : eu_per_en;
wire [`PER_MSB:0] per_addr_mux = dbg_mem_en ? dbg_mem_addr[`PER_MSB+1:1] : eu_mab[`PER_MSB:0];
wire [14:0] per_addr_ful = {{15-`PER_AWIDTH{1'b0}}, per_addr_mux};
wire [13:0] per_addr = per_addr_ful[13:0];
reg [15:0] per_dout_val;
always @ (posedge mclk or posedge puc_rst)
if (puc_rst) per_dout_val <= 16'h0000;
else per_dout_val <= per_dout;
// Frontend data Mux
//---------------------------------
// Whenever the frontend doesn't access the ROM, backup the data
// Detect whenever the data should be backuped and restored
reg fe_pmem_cen_dly;
always @(posedge mclk or posedge puc_rst)
if (puc_rst) fe_pmem_cen_dly <= 1'b0;
else fe_pmem_cen_dly <= fe_pmem_cen;
wire fe_pmem_save = ( fe_pmem_cen & ~fe_pmem_cen_dly) & ~dbg_halt_st;
wire fe_pmem_restore = (~fe_pmem_cen & fe_pmem_cen_dly) | dbg_halt_st;
`ifdef CLOCK_GATING
wire mclk_bckup;
omsp_clock_gate clock_gate_bckup (.gclk(mclk_bckup),
.clk (mclk), .enable(fe_pmem_save), .scan_enable(scan_enable));
`else
wire mclk_bckup = mclk;
`endif
reg [15:0] pmem_dout_bckup;
always @(posedge mclk_bckup or posedge puc_rst)
if (puc_rst) pmem_dout_bckup <= 16'h0000;
`ifdef CLOCK_GATING
else pmem_dout_bckup <= pmem_dout;
`else
else if (fe_pmem_save) pmem_dout_bckup <= pmem_dout;
`endif
// Mux between the ROM data and the backup
reg pmem_dout_bckup_sel;
always @(posedge mclk or posedge puc_rst)
if (puc_rst) pmem_dout_bckup_sel <= 1'b0;
else if (fe_pmem_save) pmem_dout_bckup_sel <= 1'b1;
else if (fe_pmem_restore) pmem_dout_bckup_sel <= 1'b0;
assign fe_mdb_in = pmem_dout_bckup_sel ? pmem_dout_bckup : pmem_dout;
// Execution-Unit data Mux
//---------------------------------
// Select between peripherals, RAM and ROM
reg [1:0] eu_mdb_in_sel;
always @(posedge mclk or posedge puc_rst)
if (puc_rst) eu_mdb_in_sel <= 2'b00;
else eu_mdb_in_sel <= {~eu_pmem_cen, per_en};
// Mux
assign eu_mdb_in = eu_mdb_in_sel[1] ? pmem_dout :
eu_mdb_in_sel[0] ? per_dout_val : dmem_dout;
// Debug interface data Mux
//---------------------------------
// Select between peripherals, RAM and ROM
`ifdef DBG_EN
reg [1:0] dbg_mem_din_sel;
always @(posedge mclk or posedge puc_rst)
if (puc_rst) dbg_mem_din_sel <= 2'b00;
else dbg_mem_din_sel <= {~dbg_pmem_cen, dbg_per_en};
`else
wire [1:0] dbg_mem_din_sel = 2'b00;
`endif
// Mux
assign dbg_mem_din = dbg_mem_din_sel[1] ? pmem_dout :
dbg_mem_din_sel[0] ? per_dout_val : dmem_dout;
endmodule // omsp_mem_backbone
`ifdef OMSP_NO_INCLUDE
`else
`include "openMSP430_undefines.v"
`endif
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