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repo2/mist_5200/user_io.v @ 1476

//
// user_io.v
//
// user_io for the MiST board
// http://code.google.com/p/mist-board/
//
// Copyright (c) 2014 Till Harbaum <till@harbaum.org>
//
// This source file 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 source file 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/>.
//

// parameter STRLEN and the actual length of conf_str have to match
module user_io #(parameter STRLEN=0, parameter PS2DIV=100) (
input [(8*STRLEN)-1:0] conf_str,

input clk_sys, // clock for system-related messages (kbd, joy, etc...)
input clk_sd, // clock for SD-card related messages

input SPI_CLK,
input SPI_SS_IO,
output reg SPI_MISO,
input SPI_MOSI,

output reg [31:0] joystick_0,
output reg [31:0] joystick_1,
output reg [31:0] joystick_2,
output reg [31:0] joystick_3,
output reg [31:0] joystick_4,
output reg [15:0] joystick_analog_0,
output reg [15:0] joystick_analog_1,
output [1:0] buttons,
output [1:0] switches,
output scandoubler_disable,
output ypbpr,
output reg [31:0] status,

// connection to sd card emulation
input [31:0] sd_lba,
input sd_rd,
input sd_wr,
output reg sd_ack,
output reg sd_ack_conf,
input sd_conf,
input sd_sdhc,
output reg [7:0] sd_dout, // valid on rising edge of sd_dout_strobe
output reg sd_dout_strobe,
input [7:0] sd_din,
output reg sd_din_strobe,
output reg [8:0] sd_buff_addr,

output reg img_mounted, //rising edge if a new image is mounted
output reg [31:0] img_size, // size of image in bytes

// ps2 keyboard/mouse emulation
output ps2_kbd_clk,
output reg ps2_kbd_data,
output ps2_mouse_clk,
output reg ps2_mouse_data,

// keyboard data
output reg key_pressed, // 1-make (pressed), 0-break (released)
output reg key_extended, // extended code
output reg [7:0] key_code, // key scan code
output reg key_strobe, // key data valid

// mouse data
output reg [8:0] mouse_x,
output reg [8:0] mouse_y,
output reg [7:0] mouse_flags, // YOvfl, XOvfl, dy8, dx8, 1, mbtn, rbtn, lbtn
output reg mouse_strobe, // mouse data is valid on mouse_strobe

// serial com port
input [7:0] serial_data,
input serial_strobe
);

reg [6:0] sbuf;
reg [7:0] cmd;
reg [2:0] bit_cnt; // counts bits 0-7 0-7 ...
reg [9:0] byte_cnt; // counts bytes
reg [7:0] but_sw;
reg [2:0] stick_idx;

assign buttons = but_sw[1:0];
assign switches = but_sw[3:2];
assign scandoubler_disable = but_sw[4];
assign ypbpr = but_sw[5];

// this variant of user_io is for 8 bit cores (type == a4) only
wire [7:0] core_type = 8'ha4;

// command byte read by the io controller
wire [7:0] sd_cmd = { 4'h5, sd_conf, sd_sdhc, sd_wr, sd_rd };

wire spi_sck = SPI_CLK;

// ---------------- PS2 ---------------------
// 8 byte fifos to store ps2 bytes
localparam PS2_FIFO_BITS = 3;

reg ps2_clk;
always @(negedge clk_sys) begin
integer cnt;
cnt <= cnt + 1'd1;
if(cnt == PS2DIV) begin
ps2_clk <= ~ps2_clk;
cnt <= 0;
end
end

// keyboard
reg [7:0] ps2_kbd_fifo [(2**PS2_FIFO_BITS)-1:0];
reg [PS2_FIFO_BITS-1:0] ps2_kbd_wptr;
reg [PS2_FIFO_BITS-1:0] ps2_kbd_rptr;

// ps2 transmitter state machine
reg [3:0] ps2_kbd_tx_state;
reg [7:0] ps2_kbd_tx_byte;
reg ps2_kbd_parity;

assign ps2_kbd_clk = ps2_clk || (ps2_kbd_tx_state == 0);

// ps2 transmitter
// Takes a byte from the FIFO and sends it in a ps2 compliant serial format.
reg ps2_kbd_r_inc;
always@(posedge clk_sys) begin
reg ps2_clkD;

ps2_clkD <= ps2_clk;
if (~ps2_clkD & ps2_clk) begin
ps2_kbd_r_inc <= 1'b0;

if(ps2_kbd_r_inc)
ps2_kbd_rptr <= ps2_kbd_rptr + 1'd1;

// transmitter is idle?
if(ps2_kbd_tx_state == 0) begin
// data in fifo present?
if(ps2_kbd_wptr != ps2_kbd_rptr) begin
// load tx register from fifo
ps2_kbd_tx_byte <= ps2_kbd_fifo[ps2_kbd_rptr];
ps2_kbd_r_inc <= 1'b1;

// reset parity
ps2_kbd_parity <= 1'b1;

// start transmitter
ps2_kbd_tx_state <= 4'd1;

// put start bit on data line
ps2_kbd_data <= 1'b0; // start bit is 0
end
end else begin

// transmission of 8 data bits
if((ps2_kbd_tx_state >= 1)&&(ps2_kbd_tx_state < 9)) begin
ps2_kbd_data <= ps2_kbd_tx_byte[0]; // data bits
ps2_kbd_tx_byte[6:0] <= ps2_kbd_tx_byte[7:1]; // shift down
if(ps2_kbd_tx_byte[0])
ps2_kbd_parity <= !ps2_kbd_parity;
end

// transmission of parity
if(ps2_kbd_tx_state == 9)
ps2_kbd_data <= ps2_kbd_parity;
// transmission of stop bit
if(ps2_kbd_tx_state == 10)
ps2_kbd_data <= 1'b1; // stop bit is 1

// advance state machine
if(ps2_kbd_tx_state < 11)
ps2_kbd_tx_state <= ps2_kbd_tx_state + 4'd1;
else
ps2_kbd_tx_state <= 4'd0;
end
end
end

// mouse
reg [7:0] ps2_mouse_fifo [(2**PS2_FIFO_BITS)-1:0];
reg [PS2_FIFO_BITS-1:0] ps2_mouse_wptr;
reg [PS2_FIFO_BITS-1:0] ps2_mouse_rptr;

// ps2 transmitter state machine
reg [3:0] ps2_mouse_tx_state;
reg [7:0] ps2_mouse_tx_byte;
reg ps2_mouse_parity;

assign ps2_mouse_clk = ps2_clk || (ps2_mouse_tx_state == 0);

// ps2 transmitter
// Takes a byte from the FIFO and sends it in a ps2 compliant serial format.
reg ps2_mouse_r_inc;
always@(posedge clk_sys) begin
reg ps2_clkD;

ps2_clkD <= ps2_clk;
if (~ps2_clkD & ps2_clk) begin
ps2_mouse_r_inc <= 1'b0;

if(ps2_mouse_r_inc)
ps2_mouse_rptr <= ps2_mouse_rptr + 1'd1;

// transmitter is idle?
if(ps2_mouse_tx_state == 0) begin
// data in fifo present?
if(ps2_mouse_wptr != ps2_mouse_rptr) begin
// load tx register from fifo
ps2_mouse_tx_byte <= ps2_mouse_fifo[ps2_mouse_rptr];
ps2_mouse_r_inc <= 1'b1;

// reset parity
ps2_mouse_parity <= 1'b1;

// start transmitter
ps2_mouse_tx_state <= 4'd1;

// put start bit on data line
ps2_mouse_data <= 1'b0; // start bit is 0
end
end else begin

// transmission of 8 data bits
if((ps2_mouse_tx_state >= 1)&&(ps2_mouse_tx_state < 9)) begin
ps2_mouse_data <= ps2_mouse_tx_byte[0]; // data bits
ps2_mouse_tx_byte[6:0] <= ps2_mouse_tx_byte[7:1]; // shift down
if(ps2_mouse_tx_byte[0])
ps2_mouse_parity <= !ps2_mouse_parity;
end

// transmission of parity
if(ps2_mouse_tx_state == 9)
ps2_mouse_data <= ps2_mouse_parity;

// transmission of stop bit
if(ps2_mouse_tx_state == 10)
ps2_mouse_data <= 1'b1; // stop bit is 1

// advance state machine
if(ps2_mouse_tx_state < 11)
ps2_mouse_tx_state <= ps2_mouse_tx_state + 4'd1;
else
ps2_mouse_tx_state <= 4'd0;
end
end
end

// fifo to receive serial data from core to be forwarded to io controller

// 16 byte fifo to store serial bytes
localparam SERIAL_OUT_FIFO_BITS = 6;
reg [7:0] serial_out_fifo [(2**SERIAL_OUT_FIFO_BITS)-1:0];
reg [SERIAL_OUT_FIFO_BITS-1:0] serial_out_wptr;
reg [SERIAL_OUT_FIFO_BITS-1:0] serial_out_rptr;
wire serial_out_data_available = serial_out_wptr != serial_out_rptr;
wire [7:0] serial_out_byte = serial_out_fifo[serial_out_rptr] /* synthesis keep */;
wire [7:0] serial_out_status = { 7'b1000000, serial_out_data_available};

// status[0] is reset signal from io controller and is thus used to flush
// the fifo
always @(posedge serial_strobe or posedge status[0]) begin
if(status[0] == 1) begin
serial_out_wptr <= 0;
end else begin
serial_out_fifo[serial_out_wptr] <= serial_data;
serial_out_wptr <= serial_out_wptr + 1'd1;
end
end

always@(negedge spi_sck or posedge status[0]) begin
if(status[0] == 1) begin
serial_out_rptr <= 0;
end else begin
if((byte_cnt != 0) && (cmd == 8'h1b)) begin
// read last bit -> advance read pointer
if((bit_cnt == 7) && !byte_cnt[0] && serial_out_data_available)
serial_out_rptr <= serial_out_rptr + 1'd1;
end
end
end


// SPI bit and byte counters
always@(posedge spi_sck or posedge SPI_SS_IO) begin
if(SPI_SS_IO == 1) begin
bit_cnt <= 0;
byte_cnt <= 0;
end else begin
if((bit_cnt == 7)&&(~&byte_cnt))
byte_cnt <= byte_cnt + 8'd1;

bit_cnt <= bit_cnt + 1'd1;
end
end

// SPI transmitter FPGA -> IO
reg [7:0] spi_byte_out;

always@(negedge spi_sck or posedge SPI_SS_IO) begin
if(SPI_SS_IO == 1) begin
SPI_MISO <= 1'bZ;
end else begin
SPI_MISO <= spi_byte_out[~bit_cnt];
end
end

always@(posedge spi_sck or posedge SPI_SS_IO) begin
reg [31:0] sd_lba_r;

if(SPI_SS_IO == 1) begin
spi_byte_out <= core_type;
end else begin
// read the command byte to choose the response
if(bit_cnt == 7) begin
if(!byte_cnt) cmd <= {sbuf, SPI_MOSI};

spi_byte_out <= 0;
case({(!byte_cnt) ? {sbuf, SPI_MOSI} : cmd})
// reading config string
8'h14: if(byte_cnt < STRLEN) spi_byte_out <= conf_str[(STRLEN - byte_cnt - 1)<<3 +:8];

// reading sd card status
8'h16: if(byte_cnt == 0) begin
spi_byte_out <= sd_cmd;
sd_lba_r <= sd_lba;
end
else if(byte_cnt < 5) spi_byte_out <= sd_lba_r[(4-byte_cnt)<<3 +:8];

// reading sd card write data
8'h18: spi_byte_out <= sd_din;
8'h1b:
// send alternating flag byte and data
if(byte_cnt[0]) spi_byte_out <= serial_out_status;
else spi_byte_out <= serial_out_byte;
endcase
end
end
end

// SPI receiver IO -> FPGA

reg spi_receiver_strobe_r = 0;
reg spi_transfer_end_r = 1;
reg [7:0] spi_byte_in;

// Read at spi_sck clock domain, assemble bytes for transferring to clk_sys
always@(posedge spi_sck or posedge SPI_SS_IO) begin

if(SPI_SS_IO == 1) begin
spi_transfer_end_r <= 1;
end else begin
spi_transfer_end_r <= 0;

if(bit_cnt != 7)
sbuf[6:0] <= { sbuf[5:0], SPI_MOSI };

// finished reading a byte, prepare to transfer to clk_sys
if(bit_cnt == 7) begin
spi_byte_in <= { sbuf, SPI_MOSI};
spi_receiver_strobe_r <= ~spi_receiver_strobe_r;
end
end
end

// Process bytes from SPI at the clk_sys domain
always @(posedge clk_sys) begin

reg spi_receiver_strobe;
reg spi_transfer_end;
reg spi_receiver_strobeD;
reg spi_transfer_endD;
reg [7:0] acmd;
reg [7:0] abyte_cnt; // counts bytes

reg [7:0] mouse_flags_r;
reg [7:0] mouse_x_r;

reg key_pressed_r;
reg key_extended_r;

//synchronize between SPI and sys clock domains
spi_receiver_strobeD <= spi_receiver_strobe_r;
spi_receiver_strobe <= spi_receiver_strobeD;
spi_transfer_endD <= spi_transfer_end_r;
spi_transfer_end <= spi_transfer_endD;

key_strobe <= 0;
mouse_strobe <= 0;

if (~spi_transfer_endD & spi_transfer_end) begin
abyte_cnt <= 8'd0;
end else if (spi_receiver_strobeD ^ spi_receiver_strobe) begin

if(~&abyte_cnt)
abyte_cnt <= abyte_cnt + 8'd1;

if(abyte_cnt == 0) begin
acmd <= spi_byte_in;
end else begin
case(acmd)
// buttons and switches
8'h01: but_sw <= spi_byte_in;
8'h60: if (abyte_cnt < 5) joystick_0[(abyte_cnt-1)<<3 +:8] <= spi_byte_in;
8'h61: if (abyte_cnt < 5) joystick_1[(abyte_cnt-1)<<3 +:8] <= spi_byte_in;
8'h62: if (abyte_cnt < 5) joystick_2[(abyte_cnt-1)<<3 +:8] <= spi_byte_in;
8'h63: if (abyte_cnt < 5) joystick_3[(abyte_cnt-1)<<3 +:8] <= spi_byte_in;
8'h64: if (abyte_cnt < 5) joystick_4[(abyte_cnt-1)<<3 +:8] <= spi_byte_in;
8'h04: begin
// store incoming ps2 mouse bytes
ps2_mouse_fifo[ps2_mouse_wptr] <= spi_byte_in;
ps2_mouse_wptr <= ps2_mouse_wptr + 1'd1;
if (abyte_cnt == 1) mouse_flags_r <= spi_byte_in;
else if (abyte_cnt == 2) mouse_x_r <= spi_byte_in;
else if (abyte_cnt == 3) begin
// flags: YOvfl, XOvfl, dy8, dx8, 1, mbtn, rbtn, lbtn
mouse_flags <= mouse_flags_r;
mouse_x <= { mouse_flags_r[4], mouse_x_r };
mouse_y <= { mouse_flags_r[5], spi_byte_in };
mouse_strobe <= 1;
end
end
8'h05: begin
// store incoming ps2 keyboard bytes
ps2_kbd_fifo[ps2_kbd_wptr] <= spi_byte_in;
ps2_kbd_wptr <= ps2_kbd_wptr + 1'd1;
if (abyte_cnt == 1) begin
key_extended_r <= 0;
key_pressed_r <= 1;
end
if (spi_byte_in == 8'he0) key_extended_r <= 1'b1;
else if (spi_byte_in == 8'hf0) key_pressed_r <= 1'b0;
else begin
key_extended <= key_extended_r;
key_pressed <= key_pressed_r || abyte_cnt == 1;
key_code <= spi_byte_in;
key_strobe <= 1'b1;
end
end

// joystick analog
8'h1a: begin
// first byte is joystick index
if(abyte_cnt == 1)
stick_idx <= spi_byte_in[2:0];
else if(abyte_cnt == 2) begin
// second byte is x axis
if(stick_idx == 0)
joystick_analog_0[15:8] <= spi_byte_in;
else if(stick_idx == 1)
joystick_analog_1[15:8] <= spi_byte_in;
end else if(abyte_cnt == 3) begin
// third byte is y axis
if(stick_idx == 0)
joystick_analog_0[7:0] <= spi_byte_in;
else if(stick_idx == 1)
joystick_analog_1[7:0] <= spi_byte_in;
end
end

8'h15: status <= spi_byte_in;

// status, 32bit version
8'h1e: if(abyte_cnt<5) status[(abyte_cnt-1)<<3 +:8] <= spi_byte_in;

endcase
end
end
end

// Process SD-card related bytes from SPI at the clk_sd domain
always @(posedge clk_sd) begin

reg spi_receiver_strobe;
reg spi_transfer_end;
reg spi_receiver_strobeD;
reg spi_transfer_endD;
reg sd_wrD;
reg [7:0] acmd;
reg [7:0] abyte_cnt; // counts bytes

//synchronize between SPI and sd clock domains
spi_receiver_strobeD <= spi_receiver_strobe_r;
spi_receiver_strobe <= spi_receiver_strobeD;
spi_transfer_endD <= spi_transfer_end_r;
spi_transfer_end <= spi_transfer_endD;

if(sd_dout_strobe) begin
sd_dout_strobe<= 0;
if(~&sd_buff_addr) sd_buff_addr <= sd_buff_addr + 1'b1;
end

sd_din_strobe<= 0;
sd_wrD <= sd_wr;
// fetch the first byte immediately after the write command seen
if (~sd_wrD & sd_wr) begin
sd_buff_addr <= 0;
sd_din_strobe <= 1;
end

img_mounted <= 0;

if (~spi_transfer_endD & spi_transfer_end) begin
abyte_cnt <= 8'd0;
sd_ack <= 1'b0;
sd_ack_conf <= 1'b0;
sd_dout_strobe <= 1'b0;
sd_din_strobe <= 1'b0;
sd_buff_addr <= 0;
end else if (spi_receiver_strobeD ^ spi_receiver_strobe) begin

if(~&abyte_cnt)
abyte_cnt <= abyte_cnt + 8'd1;

if(abyte_cnt == 0) begin
acmd <= spi_byte_in;

if(spi_byte_in == 8'h18) begin
sd_din_strobe <= 1'b1;
if(~&sd_buff_addr) sd_buff_addr <= sd_buff_addr + 1'b1;
end

if((spi_byte_in == 8'h17) || (spi_byte_in == 8'h18))
sd_ack <= 1'b1;

end else begin
case(acmd)

// send sector IO -> FPGA
8'h17: begin
// flag that download begins
sd_dout_strobe <= 1'b1;
sd_dout <= spi_byte_in;
end

// send sector FPGA -> IO
8'h18: begin
sd_din_strobe <= 1'b1;
if(~&sd_buff_addr) sd_buff_addr <= sd_buff_addr + 1'b1;
end

// send SD config IO -> FPGA
8'h19: begin
// flag that download begins
sd_dout_strobe <= 1'b1;
sd_ack_conf <= 1'b1;
sd_dout <= spi_byte_in;
end

8'h1c: img_mounted <= 1;

// send image info
8'h1d: if(abyte_cnt<5) img_size[(abyte_cnt-1)<<3 +:8] <= spi_byte_in;
endcase
end
end
end

endmodule
(19-19/20)