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module pci(reset,clk,frame,irdy,trdy,devsel,idsel,ad,cbe,par,stop,inta,led_out);
input reset;
input clk;
input frame;
input irdy;
output trdy;
output devsel;
input idsel;
inout [31:0] ad;
input [3:0] cbe;
inout par;
output stop;
output inta;
output [3:0] led_out;
parameter DEVICE_ID = 16'h9500;
parameter VENDOR_ID = 16'h106d; // Sequent!
parameter DEVICE_CLASS = 24'hFF0000; // Misc
parameter DEVICE_REV = 8'h01;
parameter SUBSYSTEM_ID = 16'h0001; // Card identifier
parameter SUBSYSTEM_VENDOR_ID = 16'hBEBE; // Card identifier
parameter DEVSEL_TIMING = 2'b00; // Fast!
reg [2:0] state;
reg [31:0] data;
reg [1:0] enable;
parameter EN_NONE = 0;
parameter EN_RD = 1;
parameter EN_WR = 2;
parameter EN_TR = 3;
reg memen; // respond to baseaddr?
reg [7:0] baseaddr;
reg [5:0] address;
parameter ST_IDLE = 3'b000;
parameter ST_BUSY = 3'b010;
parameter ST_MEMREAD = 3'b100;
parameter ST_MEMWRITE = 3'b101;
parameter ST_CFGREAD = 3'b110;
parameter ST_CFGWRITE = 3'b111;
parameter MEMREAD = 4'b0110;
parameter MEMWRITE = 4'b0111;
parameter CFGREAD = 4'b1010;
parameter CFGWRITE = 4'b1011;
`define LED
`ifdef LED
reg [3:0] led;
`endif
`undef STATE_DEBUG_LED
`ifdef STATE_DEBUG_LED
assign led_out = ~state;
`else
`ifdef LED
assign led_out = ~led; // board is wired for active low LEDs
`endif
`endif
assign ad = (enable == EN_RD) ? data : 32'bZ;
assign trdy = (enable == EN_NONE) ? 'bZ : (enable == EN_TR ? 1 : 0);
assign par = (enable == EN_RD) ? 0 : 'bZ;
reg devsel;
assign stop = 1'bZ;
assign inta = 1'bZ;
wire cfg_hit = ((cbe == CFGREAD || cbe == CFGWRITE) && idsel && ad[1:0] == 2'b00);
wire addr_hit = ((cbe == MEMREAD || cbe == MEMWRITE) && memen && ad[31:12] == {12'b0, baseaddr});
wire hit = cfg_hit | addr_hit;
always @(posedge clk)
begin
if (~reset) begin
state <= ST_IDLE;
enable <= EN_NONE;
baseaddr <= 0;
devsel <= 'bZ;
memen <= 0;
`ifdef LED
led <= 0;
`endif
end
else begin
case (state)
ST_IDLE: begin
enable <= EN_NONE;
devsel <= 'bZ;
if (~frame) begin
address <= ad[7:2];
if (hit) begin
state <= {1'b1, cbe[3], cbe[0]};
devsel <= 0;
// pipeline the write enable
if (cbe[0])
enable <= EN_WR;
end
else begin
state <= ST_BUSY;
enable <= EN_NONE;
end
end
end
ST_BUSY: begin
devsel <= 'bZ;
enable <= EN_NONE;
if (frame)
state <= ST_IDLE;
end
ST_CFGREAD: begin
enable <= EN_RD;
if (~irdy || trdy) begin
case (address)
0: data <= { DEVICE_ID, VENDOR_ID };
1: data <= { 5'b0, DEVSEL_TIMING, 9'b0, 14'b0, memen, 1'b0};
2: data <= { DEVICE_CLASS, DEVICE_REV };
4: data <= { 12'b0, baseaddr, 8'b0, 4'b0010 }; // baseaddr + request mem < 1Mbyte
11: data <= {SUBSYSTEM_ID, SUBSYSTEM_VENDOR_ID };
16: data <= { 24'b0, baseaddr };
default: data <= 'h00000000;
endcase
address <= address + 1;
end
if (frame && ~irdy && ~trdy) begin
devsel <= 1;
state <= ST_IDLE;
enable <= EN_TR;
end
end
ST_CFGWRITE: begin
enable <= EN_WR;
if (~irdy) begin
case (address)
4: baseaddr <= ad[19:12]; // XXX examine cbe
1: memen <= ad[1];
default: ;
endcase
address <= address + 1;
if (frame) begin
devsel <= 1;
state <= ST_IDLE;
enable <= EN_TR;
end
end
end
ST_MEMREAD: begin
enable <= EN_RD;
if (~irdy || trdy) begin
case (address)
`ifdef LED
0: data <= { 28'b0, led };
`endif
default: data <= 'h00000000;
endcase
address <= address + 1;
end
if (frame && ~irdy && ~trdy) begin
devsel <= 1;
state <= ST_IDLE;
enable <= EN_TR;
end
end
ST_MEMWRITE: begin
enable <= EN_WR;
if (~irdy) begin
case (address)
`ifdef LED
0: led <= ad[3:0];
`endif
default: ;
endcase
address <= address + 1;
if (frame) begin
devsel <= 1;
state <= ST_IDLE;
enable <= EN_TR;
end
end
end
endcase
end
end
endmodule |
阿莫论坛20周年了！感谢大家的支持与爱护！！
知道什么是神吗？其实神本来也是人，只不过神做了人做不到的事情 所以才成了神。 （头文字D, 杜汶泽）
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发表于 2011-1-7 19:48:17
楼主
