design/sys/iop/niu/rtl/fflp_fcram_arb.v

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//
// OpenSPARC T2 Processor File: fflp_fcram_arb.v
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/**********************************************************************/
/*project name:  NIU                                                  */
/*module name:   fflp_fcram_arb                                       */
/*description:   Aabitration between CPU access and flow              */
/*               classification                                       */
/*                                                                    */
/*child modules in:  none                                             */
/*interface modules:                                                  */
/*author name:       Jeanne Cai                                       */
/*date created:      16-03-2004                                       */
/*                                                                    */
/*              Copyright (c) 2004, Sun Microsystems, Inc.            */
/*                   Sun Proprietary and Confidential                 */
/*                                                                    */
/*modifications:                                                      */
/**********************************************************************/


module fflp_fcram_arb
                (
                cclk,
                reset,
                fcram_lookup_ratio,
                fc_lookup_req,
                fwd_no_fc_sched_sm,
                cpu_fcram_req_sync,
                srch_burst_done,
                cpu_burst_done_sm,

                fwd_sched,
                do_srch_cycle,
                do_cpu_cycle,
                fc_fifo_ren
                );

input           cclk;
input           reset;
input[3:0]      fcram_lookup_ratio;
input           fc_lookup_req;
input           fwd_no_fc_sched_sm;
input           cpu_fcram_req_sync;
input           srch_burst_done;
input           cpu_burst_done_sm;

output          fwd_sched;
output          do_srch_cycle;
output          do_cpu_cycle;
output          fc_fifo_ren;

reg             fwd_fc_sched_sm;
reg             cpu_sched_sm;
reg[1:0]        next_state;

wire            fwd_sched_in;
wire            fwd_sched;
wire            fwd_fc_sched;
wire            cpu_sched;
wire            fwd_sched_cnt_en;
wire[3:0]       fwd_sched_cnt_in;
wire[3:0]       fwd_sched_cnt;
wire            fwd_reqs_served;
wire[1:0]       state;

wire            cpu_fcram_req_sync_d;
wire            cpu_req_pulse;
wire            is_cpu_req_en;
wire            is_cpu_req_in;
wire            is_cpu_req;

wire            do_srch_cycle_en;
wire            do_srch_cycle_in;
wire            do_srch_cycle;
wire            do_cpu_cycle_en;
wire            do_cpu_cycle_in;
wire            do_cpu_cycle;

wire            fwd_sched_1;
wire            fwd_sched_2;
wire            fc_fifo_ren_in;
wire            fc_fifo_ren;

//state machine states
parameter
        FWD_ARB         = 2'b00,
        FWD_IDLE        = 2'b01,
        CPU_ARB         = 2'b10,
        CPU_IDLE        = 2'b11;

always @ (state or fc_lookup_req or is_cpu_req or
          srch_burst_done or cpu_burst_done_sm or
          do_cpu_cycle or fwd_reqs_served)

begin

fwd_fc_sched_sm = 1'b0;
cpu_sched_sm    = 1'b0;
next_state      = 2'b0;

case (state) //synopsys parallel_case full_case
// 0in < case -full -parallel -message "0in ERROR: case check in fflp_fcram_arb:state"

FWD_ARB:
begin
        if (do_cpu_cycle & !cpu_burst_done_sm)
        begin
                fwd_fc_sched_sm = 1'b0;
                cpu_sched_sm    = 1'b0;
                next_state      = state;
        end
        else if (fc_lookup_req)
        begin
                fwd_fc_sched_sm = 1'b1;
                next_state      = FWD_IDLE;
        end
        else if (is_cpu_req)
        begin
                cpu_sched_sm    = 1'b1;
                next_state      = CPU_IDLE;
        end
        else
                next_state      = state;

end

FWD_IDLE:
begin
        if (srch_burst_done & fwd_reqs_served)
                next_state      = CPU_ARB;
        else if (srch_burst_done)
                next_state      = FWD_ARB;
        else
                next_state      = state;
end

CPU_ARB:
begin
        if (is_cpu_req)
        begin
                cpu_sched_sm    = 1'b1;
                next_state      = CPU_IDLE;
        end
        else if (fc_lookup_req)
        begin
                fwd_fc_sched_sm = 1'b1;
                next_state      = FWD_IDLE;
        end
        else
                next_state      = FWD_ARB;
end

CPU_IDLE:
begin
                next_state      = FWD_ARB;
end

default:        next_state      = FWD_ARB;

endcase

end

assign fwd_sched_in     = fwd_fc_sched_sm | fwd_no_fc_sched_sm;

dffr #(2) state_reg        (cclk, reset, next_state,      state);
dffr #(1) fwd_sched_reg    (cclk, reset, fwd_sched_in,    fwd_sched);
dffr #(1) fwd_fc_sched_reg (cclk, reset, fwd_fc_sched_sm, fwd_fc_sched);
dffr #(1) cpu_sched_reg    (cclk, reset, cpu_sched_sm,    cpu_sched);

dffr #(1) fwd_sched_1_reg  (cclk, reset, fwd_sched,       fwd_sched_1);
dffr #(1) fwd_sched_2_reg  (cclk, reset, fwd_sched_1,     fwd_sched_2);
dffr #(1) fc_fifo_ren_reg  (cclk, reset, fc_fifo_ren_in,  fc_fifo_ren);

assign fc_fifo_ren_in   = fwd_sched | fwd_sched_1 | fwd_sched_2;


/*********************************************************************/
//allocate load balance, cpu bandwidth
/*********************************************************************/
assign fwd_reqs_served = (fwd_sched_cnt == fcram_lookup_ratio);
assign fwd_sched_cnt_en = fwd_fc_sched_sm | cpu_sched_sm;
assign fwd_sched_cnt_in = (cpu_sched_sm | fwd_reqs_served & fwd_fc_sched_sm) ? 4'b0000 : (fwd_sched_cnt + 4'd1);

dffre #(4) fwd_sched_cnt_reg (cclk, reset, fwd_sched_cnt_en, fwd_sched_cnt_in, fwd_sched_cnt);


/**********************/
//CPU Request
/**********************/
assign cpu_req_pulse    = cpu_fcram_req_sync & !cpu_fcram_req_sync_d;
assign is_cpu_req_en    = cpu_req_pulse | cpu_sched;
assign is_cpu_req_in    = cpu_req_pulse ? 1'b1 : 1'b0;

dffr  #(1) cpu_req_dly_reg (cclk, reset,                cpu_fcram_req_sync, cpu_fcram_req_sync_d);
dffre #(1) is_cpu_req_reg  (cclk, reset, is_cpu_req_en, is_cpu_req_in,      is_cpu_req);

assign do_srch_cycle_en = fwd_fc_sched | srch_burst_done;
assign do_srch_cycle_in = fwd_fc_sched ? 1'b1 : 1'b0;
assign do_cpu_cycle_en  = cpu_sched | cpu_burst_done_sm;
assign do_cpu_cycle_in  = cpu_sched ? 1'b1 : 1'b0;

dffre #(1) do_srch_cycle_reg (cclk, reset, do_srch_cycle_en, do_srch_cycle_in, do_srch_cycle);
dffre #(1) do_cpu_cycle_reg  (cclk, reset, do_cpu_cycle_en,  do_cpu_cycle_in,  do_cpu_cycle);


endmodule