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//////////////////////////////////////////////////////////////////////

////                                                              ////

////  OR1200's Power Management                                   ////

////                                                              ////

////  This file is part of the OpenRISC 1200 project              ////

////  http://www.opencores.org/cores/or1k/                        ////

////                                                              ////

////  Description                                                 ////

////  PM according to OR1K architectural specification.           ////

////                                                              ////

////  To Do:                                                      ////

////   - add support for dynamic clock gating                     ////

////                                                              ////

////  Author(s):                                                  ////

////      - Damjan Lampret, lampret@opencores.org                 ////

////                                                              ////

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////                                                              ////

//// Copyright (C) 2000 Authors and OPENCORES.ORG                 ////

////                                                              ////

//// This source file may be used and distributed without         ////

//// restriction provided that this copyright statement is not    ////

//// removed from the file and that any derivative work contains  ////

//// the original copyright notice and the associated disclaimer. ////

////                                                              ////

//// This source file is free software; you can redistribute it   ////

//// and/or modify it under the terms of the GNU Lesser General   ////

//// Public License as published by the Free Software Foundation; ////

//// either version 2.1 of the License, or (at your option) any   ////

//// later version.                                               ////

////                                                              ////

//// This source is distributed in the hope that it will be       ////

//// useful, but WITHOUT ANY WARRANTY; without even the implied   ////

//// warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR      ////

//// PURPOSE.  See the GNU Lesser General Public License for more ////

//// details.                                                     ////

////                                                              ////

//// You should have received a copy of the GNU Lesser General    ////

//// Public License along with this source; if not, download it   ////

//// from http://www.opencores.org/lgpl.shtml                     ////

////                                                              ////

//////////////////////////////////////////////////////////////////////

//

// CVS Revision History

//

// $Log: not supported by cvs2svn $

// Revision 1.1.1.1  2001/10/06 10:18:35  igorm

// no message

//

// Revision 1.2  2001/08/09 13:39:33  lampret

// Major clean-up.

//

// Revision 1.1  2001/07/20 00:46:21  lampret

// Development version of RTL. Libraries are missing.

//

//

// synopsys translate_off

`include "timescale.v"

// synopsys translate_on

`include "defines.v"

module pm(

        // RISC Internal Interface

        clk, rst, pic_wakeup, spr_write, spr_addr, spr_dat_i, spr_dat_o,

        // Power Management Interface

        pm_clksd, pm_cpustall, pm_dc_gate, pm_ic_gate, pm_dmmu_gate,

        pm_immu_gate, pm_tt_gate, pm_cpu_gate, pm_wakeup, pm_lvolt

);

//

// RISC Internal Interface

//

input           clk;            // Clock

input           rst;            // Reset

input           pic_wakeup;     // Wakeup from the PIC

input           spr_write;      // SPR Read/Write

input   [31:0]   spr_addr;       // SPR Address

input   [31:0]   spr_dat_i;      // SPR Write Data

output  [31:0]   spr_dat_o;      // SPR Read Data

//

// Power Management Interface

//

input           pm_cpustall;    // Stall the CPU

output  [3:0]    pm_clksd;       // Clock Slowdown factor

output          pm_dc_gate;     // Gate DCache clock

output          pm_ic_gate;     // Gate ICache clock

output          pm_dmmu_gate;   // Gate DMMU clock

output          pm_immu_gate;   // Gate IMMU clock

output          pm_tt_gate;     // Gate Tick Timer clock

output          pm_cpu_gate;    // Gate main RISC/CPU clock

output          pm_wakeup;      // Activate (de-gate) all clocks

output          pm_lvolt;       // Lower operating voltage

`ifdef PM_IMPLEMENTED

//

// Power Management Register bits

//

reg     [3:0]    sdf;    // Slow-down factor

reg             dme;    // Doze Mode Enable

reg             sme;    // Sleep Mode Enable

reg             dcge;   // Dynamic Clock Gating Enable

//

// Internal wires

//

wire            pmr_sel; // PMR select

//

// PMR address decoder (partial decoder)

//

`ifdef PM_PARTIAL_DECODING

assign pmr_sel = (spr_addr[`SPRGRP_BITS] == `SPRGRP_PM) ? 1'b1 : 1'b0;

`else

assign pmr_sel = ((spr_addr[`SPRGRP_BITS] == `SPRGRP_PM) &&

                  (spr_addr[`SPROFS_BITS] == `PM_OFS_PMR)) ? 1'b1 : 1'b0;

`endif

//

// Write to PMR and also PMR[DME]/PMR[SME] reset when

// pic_wakeup is asserted

//

always @(posedge clk or posedge rst)

        if (rst)

                {dcge, sme, dme, sdf} <= 7'b0;

        else if (pmr_sel && spr_write) begin

                sdf <= #1 spr_dat_i[`PM_PMR_SDF];

                dme <= #1 spr_dat_i[`PM_PMR_DME];

                sme <= #1 spr_dat_i[`PM_PMR_SME];

                dcge <= #1 spr_dat_i[`PM_PMR_DCGE];

        end

        else if (pic_wakeup) begin

                dme <= #1 1'b0;

                sme <= #1 1'b0;

        end

//

// Read PMR

//

`ifdef PM_READREGS

assign spr_dat_o[`PM_PMR_SDF] = sdf;

assign spr_dat_o[`PM_PMR_DME] = dme;

assign spr_dat_o[`PM_PMR_SME] = sme;

assign spr_dat_o[`PM_PMR_DCGE] = dcge;

`ifdef PM_UNUSED_ZERO

assign spr_dat_o[`PM_PMR_UNUSED] = 25'b0;

`endif

`endif

//

// Generate pm_clksd

//

assign pm_clksd = sdf;

//

// Statically generate all clock gate outputs

// TODO: add dynamic clock gating feature

//

assign pm_cpu_gate = (dme | sme) & ~pic_wakeup;

assign pm_dc_gate = pm_cpu_gate;

assign pm_ic_gate = pm_cpu_gate;

assign pm_dmmu_gate = pm_cpu_gate;

assign pm_immu_gate = pm_cpu_gate;

assign pm_tt_gate = sme & ~pic_wakeup;

//

// Assert pm_wakeup when pic_wakeup is asserted

//

assign pm_wakeup = pic_wakeup;

//

// Assert pm_lvolt when pm_cpu_gate or pm_cpustall are asserted

//

assign pm_lvolt = pm_cpu_gate | pm_cpustall;

`else

//

// When PM is not implemented, drive all outputs as would when PM is disabled

//

assign pm_clksd = 4'b0;

assign pm_cpu_gate = 1'b0;

assign pm_dc_gate = 1'b0;

assign pm_ic_gate = 1'b0;

assign pm_dmmu_gate = 1'b0;

assign pm_immu_gate = 1'b0;

assign pm_tt_gate = 1'b0;

assign pm_wakeup = 1'b1;

assign pm_lvolt = 1'b0;

//

// Read PMR

//

`ifdef PM_READREGS

assign spr_dat_o[`PM_PMR_SDF] = 4'b0;

assign spr_dat_o[`PM_PMR_DME] = 1'b0;

assign spr_dat_o[`PM_PMR_SME] = 1'b0;

assign spr_dat_o[`PM_PMR_DCGE] = 1'b0;

`ifdef PM_UNUSED_ZERO

assign spr_dat_o[`PM_PMR_UNUSED] = 25'b0;

`endif

`endif

`endif

endmodule