Initial commit of OpenSPARC T2 design and verification files.

[OpenSPARC-T2-DV] / design / sys / iop / ccu / rtl / ccu_divider.v

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// OpenSPARC T2 Processor File: ccu_divider.v
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module ccu_divider (
	rst_n,
	div,
	clkin,
	clkout,
	phase_180
);	

input		rst_n;
input [4:0]	div;
input		clkin;
output		clkout;
output		phase_180;

wire		rst_n;
wire [4:0]	div;
wire		clkin;
wire			clkout; // ECO
wire		pre_phase_180;
wire		phase_180;

// wire		clkout_tmp; // ECO
wire 		odd;
wire  [4:0] cnt;
wire [3:0] div_by2;
wire			flip;

wire reset;

reg clkout_d_;	// ECO
wire clkout_q_;	// ECO

assign div_by2 = div[4:1]; 
assign odd = div[0]; 

reg	[4:0]	cnt_in;
reg		flip_in,pre_phase_180_in;
always @ (cnt or div_by2 or div  ) begin
		if (cnt == div_by2) begin
			cnt_in = cnt + 5'b1;
			flip_in = 1'b1;
			pre_phase_180_in = 1'b1;
		end else if (cnt == div) begin
			cnt_in = 5'h00; 
			flip_in = 1'b1;
			pre_phase_180_in = 1'b0;
		end else begin
			cnt_in = cnt + 5'b1; 
			flip_in = 1'b0;
			pre_phase_180_in = 1'b0;
		end
end

assign reset = ~rst_n;

ccu_msff_arst_4x_5 cnt_bank5 ( 
	.q(cnt), 
	.so(), 
	.d(cnt_in), 
	.l1clk(clkin),
	.si(1'b0), 
	.siclk(1'b0), 
	.soclk(1'b0), 
	.reset_n(rst_n) 
);


my_msff_arst_4x 	flip_0 ( .q(flip), .so(), .d(flip_in), .l1clk(clkin),
						.si(1'b0), .siclk(1'b0), .soclk(1'b0), .reset(reset) );

my_msff_arst_4x 	pre_phase_180_0 ( .q(pre_phase_180), .so(), .d(pre_phase_180_in), .l1clk(clkin),
						.si(1'b0), .siclk(1'b0), .soclk(1'b0), .reset(reset) );



// flip => output is inverted else maintain state 

wire	clkout_tmp_in;
wire	clkout_tmp_;

// assign	clkout_tmp_in =  flip ? clkout_tmp : ~clkout_tmp;
assign clkout_tmp_in =  flip ^ clkout_tmp_; 	// ECO

my_msff_arst_4x      clkout_tmp_0 (	 
	// .q(clkout_tmp_), .so(), .d(clkout_tmp_in), .l1clk(clkin),
	.q(clkout_q_), .so(), .d(clkout_d_), .l1clk(clkin),	// ECO
    .si(1'b0), .siclk(1'b0), .soclk(1'b0), .reset(reset) );

// assign	clkout_tmp = ~clkout_tmp_; 	// ECO 

// just pipe one stage 
wire	phase_180_in;
wire 	phase_180_;

assign	phase_180_in	= ~pre_phase_180;

my_msff_arst_4x      phase_180_0 ( 
   .q(phase_180_), .so(), .d(phase_180_in), .l1clk(clkin),
   .si(1'b0), .siclk(1'b0), .soclk(1'b0), .reset(reset) );

assign	phase_180 = ~phase_180_;


// ------------------------------------------------------------
// Quick & dirty fix to shift clocks generated by N-8 cycles 
// when N is (effective) 11 or 15 for DTM
// ------------------------------------------------------------

wire [6:0] clk_shift_;
wire [6:0] clk_shift;

assign clk_shift = ~clk_shift_ ;
 
ccu_msff_arst_4x_7 shift_bank_7 (  
	.q(clk_shift_[6:0]), 
	.so (), 
	.d({clk_shift_[5:0], clkout_tmp_in}) , // ECO .d({clk_shift_[5:0], clkout_tmp_}) , 
	.l1clk (clkin), 
	.si (1'b0), 
	.siclk (1'b0), 
	.soclk (1'b0), 
	.reset_n (rst_n) 
);


// dtm shift not needed for div eff == 8; only for 11 & 15
wire dtm_mode = ((div == 5'h0A) || (div == 5'h0E)); 

assign clkout = ~clkout_q_;	// ECO
assign clkout_tmp_ = dtm_mode ? clk_shift_[0] : clkout_q_ ;   // ECO

always @(div or clkout_tmp_in or clk_shift_) begin // ECO @(div or clkout_tmp or clk_shift) 
	case (div)
		5'h0A: 	 clkout_d_ = clk_shift_[2]; // 11 => shift 3 cycles // ECO
		5'h0E: 	 clkout_d_ = clk_shift_[6]; // 15 => shift 7 cycles // ECO
		default: clkout_d_ = clkout_tmp_in;   // else no shift  // ECO
	endcase 
end

// end of quick fix
// ------------------------------------------------------------

endmodule