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caravel/verilog/dv/caravel/spiflash.v

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`default_nettype none
/*
* SPDX-FileCopyrightText: 2017 Clifford Wolf
*
* PicoSoC - A simple example SoC using PicoRV32
*
* Copyright (C) 2017 Clifford Wolf <clifford@clifford.at>
*
* Permission to use, copy, modify, and/or distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*
* SPDX-License-Identifier: ISC
*/
`timescale 1 ns / 1 ps
//
// Simple SPI flash simulation model
//
// This model samples io input signals 1ns before the SPI clock edge and
// updates output signals 1ns after the SPI clock edge.
//
// Supported commands:
// AB, B9, FF, 03, BB, EB, ED
//
// Well written SPI flash data sheets:
// Cypress S25FL064L http://www.cypress.com/file/316661/download
// Cypress S25FL128L http://www.cypress.com/file/316171/download
//
module spiflash #(
parameter FILENAME = "firmware.hex"
)(
input csb,
input clk,
inout io0, // MOSI
inout io1, // MISO
inout io2,
inout io3
);
localparam verbose = 0;
localparam integer latency = 8;
reg [7:0] buffer;
reg [3:0] reset_count = 0;
reg [3:0] reset_monitor = 0;
integer bitcount = 0;
integer bytecount = 0;
integer dummycount = 0;
reg [7:0] spi_cmd;
reg [7:0] xip_cmd = 0;
reg [23:0] spi_addr;
reg [7:0] spi_in;
reg [7:0] spi_out;
reg spi_io_vld;
reg powered_up = 0;
localparam [3:0] mode_spi = 1;
localparam [3:0] mode_dspi_rd = 2;
localparam [3:0] mode_dspi_wr = 3;
localparam [3:0] mode_qspi_rd = 4;
localparam [3:0] mode_qspi_wr = 5;
localparam [3:0] mode_qspi_ddr_rd = 6;
localparam [3:0] mode_qspi_ddr_wr = 7;
reg [3:0] mode = 0;
reg [3:0] next_mode = 0;
reg io0_oe = 0;
reg io1_oe = 0;
reg io2_oe = 0;
reg io3_oe = 0;
reg io0_dout = 0;
reg io1_dout = 0;
reg io2_dout = 0;
reg io3_dout = 0;
assign #1 io0 = io0_oe ? io0_dout : 1'bz;
assign #1 io1 = io1_oe ? io1_dout : 1'bz;
assign #1 io2 = io2_oe ? io2_dout : 1'bz;
assign #1 io3 = io3_oe ? io3_dout : 1'bz;
wire io0_delayed;
wire io1_delayed;
wire io2_delayed;
wire io3_delayed;
assign #1 io0_delayed = io0;
assign #1 io1_delayed = io1;
assign #1 io2_delayed = io2;
assign #1 io3_delayed = io3;
// 16 MB (128Mb) Flash
reg [7:0] memory [0:16*1024*1024-1];
initial begin
$display("Memory 5 bytes = 0x%02x 0x%02x 0x%02x 0x%02x 0x%02x",
memory[1048576], memory[1048577], memory[1048578],
memory[1048579], memory[1048580]);
$display("Reading %s", FILENAME);
$readmemh(FILENAME, memory);
$display("%s loaded into memory", FILENAME);
$display("Memory 5 bytes = 0x%02x 0x%02x 0x%02x 0x%02x 0x%02x",
memory[1048576], memory[1048577], memory[1048578],
memory[1048579], memory[1048580]);
end
task spi_action;
begin
spi_in = buffer;
if (bytecount == 1) begin
spi_cmd = buffer;
if (spi_cmd == 8'h ab)
powered_up = 1;
if (spi_cmd == 8'h b9)
powered_up = 0;
if (spi_cmd == 8'h ff)
xip_cmd = 0;
end
if (powered_up && spi_cmd == 'h 03) begin
if (bytecount == 2)
spi_addr[23:16] = buffer;
if (bytecount == 3)
spi_addr[15:8] = buffer;
if (bytecount == 4)
spi_addr[7:0] = buffer;
if (bytecount >= 4) begin
buffer = memory[spi_addr];
spi_addr = spi_addr + 1;
end
end
if (powered_up && spi_cmd == 'h bb) begin
if (bytecount == 1)
mode = mode_dspi_rd;
if (bytecount == 2)
spi_addr[23:16] = buffer;
if (bytecount == 3)
spi_addr[15:8] = buffer;
if (bytecount == 4)
spi_addr[7:0] = buffer;
if (bytecount == 5) begin
xip_cmd = (buffer == 8'h a5) ? spi_cmd : 8'h 00;
mode = mode_dspi_wr;
dummycount = latency;
end
if (bytecount >= 5) begin
buffer = memory[spi_addr];
spi_addr = spi_addr + 1;
end
end
if (powered_up && spi_cmd == 'h eb) begin
if (bytecount == 1)
mode = mode_qspi_rd;
if (bytecount == 2)
spi_addr[23:16] = buffer;
if (bytecount == 3)
spi_addr[15:8] = buffer;
if (bytecount == 4)
spi_addr[7:0] = buffer;
if (bytecount == 5) begin
xip_cmd = (buffer == 8'h a5) ? spi_cmd : 8'h 00;
mode = mode_qspi_wr;
dummycount = latency;
end
if (bytecount >= 5) begin
buffer = memory[spi_addr];
spi_addr = spi_addr + 1;
end
end
if (powered_up && spi_cmd == 'h ed) begin
if (bytecount == 1)
next_mode = mode_qspi_ddr_rd;
if (bytecount == 2)
spi_addr[23:16] = buffer;
if (bytecount == 3)
spi_addr[15:8] = buffer;
if (bytecount == 4)
spi_addr[7:0] = buffer;
if (bytecount == 5) begin
xip_cmd = (buffer == 8'h a5) ? spi_cmd : 8'h 00;
mode = mode_qspi_ddr_wr;
dummycount = latency;
end
if (bytecount >= 5) begin
buffer = memory[spi_addr];
spi_addr = spi_addr + 1;
end
end
spi_out = buffer;
spi_io_vld = 1;
if (verbose) begin
if (bytecount == 1)
$write("<SPI-START>");
$write("<SPI:%02x:%02x>", spi_in, spi_out);
end
end
endtask
task ddr_rd_edge;
begin
buffer = {buffer, io3_delayed, io2_delayed, io1_delayed, io0_delayed};
bitcount = bitcount + 4;
if (bitcount == 8) begin
bitcount = 0;
bytecount = bytecount + 1;
spi_action;
end
end
endtask
task ddr_wr_edge;
begin
io0_oe = 1;
io1_oe = 1;
io2_oe = 1;
io3_oe = 1;
io0_dout = buffer[4];
io1_dout = buffer[5];
io2_dout = buffer[6];
io3_dout = buffer[7];
buffer = {buffer, 4'h 0};
bitcount = bitcount + 4;
if (bitcount == 8) begin
bitcount = 0;
bytecount = bytecount + 1;
spi_action;
end
end
endtask
always @(csb) begin
if (csb) begin
if (verbose) begin
$display("");
$fflush;
end
buffer = 0;
bitcount = 0;
bytecount = 0;
mode = mode_spi;
io0_oe = 0;
io1_oe = 0;
io2_oe = 0;
io3_oe = 0;
// Handle MBR. If in XIP continuous mode, the following
// 8 clock cycles are normally not expected to be a command.
// If followed by CSB high, however, if the address bits
// are consistent with io0 == 1 for 8 clk cycles, then an
// MBR has been issued and the system must exit XIP
// continuous mode.
if (xip_cmd == 8'hbb || xip_cmd == 8'heb
|| xip_cmd == 8'hed) begin
if (reset_count == 4'h8 && reset_monitor == 4'h8) begin
xip_cmd = 8'h00;
spi_cmd = 8'h03;
end
end
end else
if (xip_cmd) begin
buffer = xip_cmd;
bitcount = 0;
bytecount = 1;
spi_action;
end
end
always @(posedge clk or posedge csb) begin
if (csb == 1'b1) begin
reset_count = 0;
reset_monitor = 0;
end else begin
if (reset_count < 4'h9) begin
reset_count = reset_count + 1;
if (io0_delayed == 1'b1) begin
reset_monitor = reset_monitor + 1;
end
end
end
end
always @(csb, clk) begin
spi_io_vld = 0;
if (!csb && !clk) begin
if (dummycount > 0) begin
io0_oe = 0;
io1_oe = 0;
io2_oe = 0;
io3_oe = 0;
end else
case (mode)
mode_spi: begin
io0_oe = 0;
io1_oe = 1;
io2_oe = 0;
io3_oe = 0;
io1_dout = buffer[7];
end
mode_dspi_rd: begin
io0_oe = 0;
io1_oe = 0;
io2_oe = 0;
io3_oe = 0;
end
mode_dspi_wr: begin
io0_oe = 1;
io1_oe = 1;
io2_oe = 0;
io3_oe = 0;
io0_dout = buffer[6];
io1_dout = buffer[7];
end
mode_qspi_rd: begin
io0_oe = 0;
io1_oe = 0;
io2_oe = 0;
io3_oe = 0;
end
mode_qspi_wr: begin
io0_oe = 1;
io1_oe = 1;
io2_oe = 1;
io3_oe = 1;
io0_dout = buffer[4];
io1_dout = buffer[5];
io2_dout = buffer[6];
io3_dout = buffer[7];
end
mode_qspi_ddr_rd: begin
ddr_rd_edge;
end
mode_qspi_ddr_wr: begin
ddr_wr_edge;
end
endcase
if (next_mode) begin
case (next_mode)
mode_qspi_ddr_rd: begin
io0_oe = 0;
io1_oe = 0;
io2_oe = 0;
io3_oe = 0;
end
mode_qspi_ddr_wr: begin
io0_oe = 1;
io1_oe = 1;
io2_oe = 1;
io3_oe = 1;
io0_dout = buffer[4];
io1_dout = buffer[5];
io2_dout = buffer[6];
io3_dout = buffer[7];
end
endcase
mode = next_mode;
next_mode = 0;
end
end
end
always @(posedge clk) begin
if (!csb) begin
if (dummycount > 0) begin
dummycount = dummycount - 1;
end else
case (mode)
mode_spi: begin
buffer = {buffer, io0};
bitcount = bitcount + 1;
if (bitcount == 8) begin
bitcount = 0;
bytecount = bytecount + 1;
spi_action;
end
end
mode_dspi_rd, mode_dspi_wr: begin
buffer = {buffer, io1, io0};
bitcount = bitcount + 2;
if (bitcount == 8) begin
bitcount = 0;
bytecount = bytecount + 1;
spi_action;
end
end
mode_qspi_rd, mode_qspi_wr: begin
buffer = {buffer, io3, io2, io1, io0};
bitcount = bitcount + 4;
if (bitcount == 8) begin
bitcount = 0;
bytecount = bytecount + 1;
spi_action;
end
end
mode_qspi_ddr_rd: begin
ddr_rd_edge;
end
mode_qspi_ddr_wr: begin
ddr_wr_edge;
end
endcase
end
end
endmodule
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