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//
// Copyright 2011 Ettus Research LLC
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program 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 General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program. If not, see <http://www.gnu.org/licenses/>.
//
module gpio_atr
#(parameter BASE = 0,
parameter WIDTH = 32)
(input clk, input reset,
input set_stb, input [7:0] set_addr, input [31:0] set_data,
input rx, input tx,
inout [WIDTH-1:0] gpio,
output reg [31:0] gpio_readback
);
wire [WIDTH-1:0] ddr, in_idle, in_tx, in_rx, in_fdx;
reg [WIDTH-1:0] rgpio, igpio;
reg [WIDTH-1:0] gpio_pipe;
setting_reg #(.my_addr(BASE+0), .width(WIDTH)) reg_idle
(.clk(clk),.rst(reset),.strobe(set_stb),.addr(set_addr), .in(set_data),
.out(in_idle),.changed());
setting_reg #(.my_addr(BASE+1), .width(WIDTH)) reg_rx
(.clk(clk),.rst(reset),.strobe(set_stb),.addr(set_addr), .in(set_data),
.out(in_rx),.changed());
setting_reg #(.my_addr(BASE+2), .width(WIDTH)) reg_tx
(.clk(clk),.rst(reset),.strobe(set_stb),.addr(set_addr), .in(set_data),
.out(in_tx),.changed());
setting_reg #(.my_addr(BASE+3), .width(WIDTH)) reg_fdx
(.clk(clk),.rst(reset),.strobe(set_stb),.addr(set_addr), .in(set_data),
.out(in_fdx),.changed());
setting_reg #(.my_addr(BASE+4), .width(WIDTH)) reg_ddr
(.clk(clk),.rst(reset),.strobe(set_stb),.addr(set_addr), .in(set_data),
.out(ddr),.changed());
always @(posedge clk)
case({tx,rx})
2'b00: rgpio <= in_idle;
2'b01: rgpio <= in_rx;
2'b10: rgpio <= in_tx;
2'b11: rgpio <= in_fdx;
endcase // case ({tx,rx})
integer n;
always @*
for(n=0;n<WIDTH;n=n+1)
igpio[n] <= ddr[n] ? rgpio[n] : 1'bz;
assign gpio = igpio;
// Double pipeline stage for timing, first flop is in IOB, second in core logic.
always @(posedge clk) begin
gpio_pipe <= gpio;
gpio_readback <= gpio_pipe;
end
endmodule // gpio_atr
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