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Added GPIO

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David Harris 2021-01-15 00:19:31 -05:00
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///////////////////////////////////////////
// gpio.sv
//
// Written: David_Harris@hmc.edu 14 January 2021
// Modified:
//
// Purpose: General Purpose I/O peripheral
// See FE310-G002-Manual-v19p05 for specifications
// No interrupts, drive strength, or pull-ups supported
//
// A component of the Wally configurable RISC-V project.
//
// Copyright (C) 2021 Harvey Mudd College & Oklahoma State University
//
// Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation
// files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy,
// modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software
// is furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
// OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
// BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT
// OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
///////////////////////////////////////////
`include "wally-macros.sv"
module gpio #(parameter XLEN=32) (
input logic clk, reset,
input logic [1:0] MemRWM,
input logic [7:0] ByteMaskM,
input logic [7:0] AdrM,
input logic [XLEN-1:0] WdM,
output logic [XLEN-1:0] RdM,
input logic [31:0] GPIOPinsIn,
output logic [31:0] GPIOPinsOut, GPIOPinsEn);
logic [31:0] INPUT_VAL INPUT_EN, OUTPUT_EN, OUTPUT_VAL;
logic [XLEN-1:0] read, write;
logic [15:0] entry;
logic memread, memwrite;
assign memread = MemRWM[1];
assign memwrite = MemRWM[0];
// word aligned reads
generate
if (XLEN==64)
assign #2 entry = {AdrM[7:3], 3'b000};
else
assign #2 entry = {AdrM[7:2], 2'b00};
endgenerate
assign INPUT_VAL = GPIOPinsIn & INPUT_EN;
assign GPIOPinsOut = OUTPUT_VAL;
assign GPIOPinsEn = OUTPUT_EN;
// register access
generate
if (XLEN==64) begin
always_comb begin
case(entry)
8'h00: read = {INPUT_EN, INPUT_VAL};
8'h08: read = {OUTPUT_VAL, OUTPUT_EN};
8'h40: read = 0; // OUT_XOR reads as 0
default: read = 0;
endcase
write=read;
if (ByteMaskM[0]) write[7:0] = WdM[7:0];
if (ByteMaskM[1]) write[15:8] = WdM[15:8];
if (ByteMaskM[2]) write[23:16] = WdM[23:16];
if (ByteMaskM[3]) write[31:24] = WdM[31:24];
if (ByteMaskM[4]) write[39:32] = WdM[39:32];
if (ByteMaskM[5]) write[47:40] = WdM[47:40];
if (ByteMaskM[6]) write[55:48] = WdM[55:48];
if (ByteMaskM[7]) write[63:56] = WdM[63:56];
end
always_ff @(posedge clk or posedge reset)
if (reset) begin
INPUT_EN <= 0;
OUTPUT_EN <= 0;
// OUTPUT_VAL <= 0; // spec indicates synchronous rset (software control)
end else begin
if (entry == 8'h00) INPUT_EN <= write[63:32];
if (entry == 8'h08) {OUTPUT_VAL, OUTPUT_EN} <= write;
if (entry == 8'h40) OUTPUT_VAL <= OUTPUT_VAL ^ write[31:0]; // OUT_XOR
end
end else begin // 32-bit
always_comb begin
case(entry)
8'h00: read = INPUT_VAL;
8'h04: read = INPUT_EN;
8'h08: read = OUTPUT_EN;
8'h0C: read = OUTPUT_VAL;
8'h40: read = 0; // OUT_XOR reads as 0
default: read = 0;
endcase
write=read;
if (ByteMaskM[0]) write[7:0] = WdM[7:0];
if (ByteMaskM[1]) write[15:8] = WdM[15:8];
if (ByteMaskM[2]) write[23:16] = WdM[23:16];
if (ByteMaskM[3]) write[31:24] = WdM[31:24];
end
always_ff @(posedge clk or posedge reset)
if (reset) begin
INPUT_EN <= 0;
OUTPUT_EN <= 0;
//OUTPUT_VAL <= 0;// spec indicates synchronous rset (software control)
end else begin
if (entry == 8'h04) INPUT_EN <= write;
if (entry == 8'h08) OUTPUT_EN <= write;
if (entry == 8'h0C) OUTPUT_VAL <= write;
if (entry == 8'h40) OUTPUT_VAL <= OUTPUT_VAL ^ write; // OUT_XOR
end
end
endgenerate
// read
assign RdM = memread ? read: 0;
endmodule