/*
 *       controller.v
 *       
 *   Copyright (C) 2018, 2109, 2020, 2021 Mind Chasers Inc.
 *
 *   Licensed under the Apache License, Version 2.0 (the "License");
 *   you may not use this file except in compliance with the License.
 *   You may obtain a copy of the License at
 *
 *       http://www.apache.org/licenses/LICENSE-2.0
 *
 *   Unless required by applicable law or agreed to in writing, software
 *   distributed under the License is distributed on an "AS IS" BASIS,
 *   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *   See the License for the specific language governing permissions and
 *   limitations under the License.
 *	
 *	function: FPGA internal state machine controller
 *	
 */
 
`timescale 1ns /10ps

module controller	#(parameter ADDR_SZ = 7)
(
	input rstn,
	input clk,
	input init,
	input pulse_100ms,
	
	// PCS status lines
	input [3:0] pcs_rx_error,
	input [1:0] pll_lol,
	
	// link status
	input [3:0] port_up,
	
	// mdio_controller interface
	output	reg mdio_cont_start,
	input 	mdio_cont_done,
	output reg [ADDR_SZ-1:0] mdio_routine_addr,
	input mdio_run,			// the mdio controller is active
	
	// mdio_data params
	output reg [4:0] mdio_page,
	output reg [4:0] mdio_reg_addr,
	output reg [7:0] mdio_w_data_h, 
	output reg [7:0] mdio_w_data_l,
	
	// bin_to_ascii interface for MDIO or CONT -> bin_to_ascii -> FIFO -> I2C
	input bin_to_ascii_run,		// asserted if block is active and writing FIFO
	
	// sync_fifo interface: controller to fifo
	output fifo_mux_sel,		// 0 is self, 1 is mdio_controller
	output	reg fifo_we,
	output reg [6:0] read_fifo_d_o,
		
	// i2c interface: i2c to controller
	input  i2c_rx_we,
	input  i2c_rx_done,
	input [7:0]	i2c_d_in,
	
	// DCU Resets
	output [1:0] pcs_rst_dual,
	output [1:0] serdes_rst_dual,
	output [1:0] tx_serdes_rst,
	
	// Channel 
	output [3:0] phy_resetn,
	output [3:0] mac_reset,

	output [3:0] tx_pcs_rst,
	output [3:0] rx_serdes_rst,
	output [3:0] rx_pcs_rst,
	
	output reg [1:0]  mdio_mux_sel,
	
	// TX custom packet
	output reg tx_custom

);

	// state encoding  
	localparam 	BUFFER_SZ = 8;	// index starts at 1, 0 is cmd

	localparam 	S0= 4'h0, S1=4'h1, S2=4'h2, S3=4'h3,
				S4= 4'h4, S5=4'h5, S6=4'h6, S7=4'h7,
				S8= 4'h8, S9=4'h9, S10=4'ha, S11=4'hb,
				S12= 4'hc, S13=4'hd, S14=4'he, S15=4'hf;

	// ascii codes we use
	localparam	ASCIIc	= 7'h63,		// channel resets
				ASCIId	= 7'h64,		// set and dump page
				ASCIIf  = 7'h66,		// FIFO control
				ASCIIi 	= 7'h69,		// init ( sgmii mode )
				ASCIIl 	= 7'h6c,		// link status
				ASCIIm	= 7'h6d,		// mdio mux
				ASCIIp	= 7'h70,		// PCS /SERDES block status
				ASCIIq  = 7'h71,
				ASCIIr	= 7'h72,		// set address and read reg
				ASCIIs 	= 7'h73,		// show mdio line status
				ASCIIt	= 7'h74,		// transmit test packet
				ASCIIu	= 7'h75,
				ASCIIw	= 7'h77,		// write reg at preset page and address
				ASCIIx	= 7'h78,		// control word
				ASCIIy	= 7'h79,		// extended read
				ASCIIz	= 7'h7a,		// extended write
				ASCII_	= 7'h5f,
				LF  	= 7'h0a,
				CR 		= 7'h0d;

	reg [1:0] x_reg[0:3];	// ASCIIx: phy_reset and mac_reset
	reg [2:0] c_reg[0:3];	// ASCIIc one reg per channel
	reg [2:0] u_reg[0:1];	// 2 DCU's: pcs_rst_dual, serdes_rst_dual, tx_serdes_rst
	
	reg [3:0] cont_state;
	reg [3:0] cnt;				// input cnt, 0 is cmd, 1-8 are buffer, beyond are thrown out & flag is set
	reg [6:0] cmd;
	integer i;
	
	reg [6:0] buffer [1:BUFFER_SZ];	// data buffer
	
	reg mdio_cmd, cont_cmd;
	wire rx_cmd;
	reg mdio_cont_busy;
	
	wire[5:0] pcs_s;
	wire[3:0] link_s;
	
	reg cont_start, cont_busy, cont_done;
	
	assign pcs_s = { pll_lol, pcs_rx_error };
	assign link_s = port_up;
	
	/* 
	*  	main state machine for controller 
	*/
    always @(posedge clk or negedge rstn) 
		begin 
			if ( !rstn )
				cont_state <= S0;
			else
				case (cont_state)
					S0: cont_state <= S1;			// S0 is default on reset
					S1: if ( rx_cmd && cont_cmd )
							cont_state <= S2;	
						else if ( rx_cmd ) 
							cont_state <= S3;
					S2: cont_state <= S3;			// respond to cont cmd
					S3: if ( !cont_busy ) 
							cont_state <= S4;
					S4: if ( !mdio_cont_busy ) 
							cont_state <= S1;
					default: cont_state <= cont_state;	
				endcase
		end
		
/*
*	Controller Tasks, controller always runs upon rx_cmd.  
*	Other tasks will hold off until cont_done asserts
*/
    always @(posedge clk or negedge rstn) 
		begin 
			if ( !rstn )
				cont_start <= 1'b0;
			else if ( rx_cmd )
				cont_start <= 1'b1;
			else
				cont_start <= 1'b0;
		end
		
	// cont_busy 
    always @(posedge clk or negedge rstn) 
		begin 
			if ( !rstn )
				cont_busy <= 1'b0;
			else if ( cont_start )
				cont_busy <= 1'b1;
			else if ( cont_done )
				cont_busy <= 1'b0;		
		end	
		
	// cont_done
	always @(posedge clk or negedge rstn) 
	begin 
		if ( !rstn )
			cont_done <= 1'b0;
		else if ( cont_busy )
			cont_done <= 1'b1;
		else
			cont_done <= 1'b0;		
	end	

	always @(cmd)
		begin
			if ( cmd == ASCIIp || cmd == ASCIIl )
				cont_cmd <= 1'b1;
			else
				cont_cmd <= 1'b0;
		end	

	/*
	*	MDIO controller related
	*/
	always @(cmd)
		begin
			if ( cmd == ASCIIi || cmd == ASCIIs || cmd == ASCIId || cmd == ASCIIr || cmd == ASCIIw || cmd == ASCIIy || cmd == ASCIIz  )
				mdio_cmd <= 1'b1;
			else
				mdio_cmd <= 1'b0;
		end
	
	
    always @(posedge clk or negedge rstn) 
		begin 
			if ( !rstn )
				mdio_cont_start <= 1'b0;
			else if ( cont_done && mdio_cmd )
				mdio_cont_start <= 1'b1;
			else
				mdio_cont_start <= 1'b0;
		end
		
	/*
	* 	driver: mdio_route_addr
	*/
    always @(posedge clk or negedge rstn) 
		begin 
			if ( !rstn )
				mdio_routine_addr <= 'd0;
			else if ( cont_done && mdio_cmd )
				if ( cmd == ASCIIi )
					mdio_routine_addr <= 'd0;
				else if ( cmd == ASCIIs )
					mdio_routine_addr <= 'd20;
				else if ( cmd == ASCIId )
					mdio_routine_addr <= 'd25;
				else if ( cmd == ASCIIr )
					mdio_routine_addr <= 'd48;
				else if ( cmd == ASCIIw )
					mdio_routine_addr <= 'd50;
				else if ( cmd == ASCIIy )
					mdio_routine_addr <= 'd60;
				else if ( cmd == ASCIIz )
					mdio_routine_addr <= 'd80;
		end
		
	// mdio_cont_busy
    always @(posedge clk or negedge rstn) 
		begin 
			if ( !rstn )
				mdio_cont_busy <= 1'b0;
			else if ( mdio_cont_start )
				mdio_cont_busy <= 1'b1;
			else if ( mdio_cont_done )
				mdio_cont_busy <= 1'b0;		
		end
		
	/* fifo_mux_sel = 1 when controller does NOT have FIFO bus */
	assign fifo_mux_sel = mdio_cont_busy | mdio_run;
		
	/* set mdio page 	*/
    always @(posedge clk or negedge rstn) 
		begin 
			if ( !rstn )
				mdio_page <= 'd0;
			else if ( rx_cmd && cmd == ASCIId )
				mdio_page <= { buffer[1][0], buffer[2][3:0] };
		end	
		
	/* set mdio_reg_addr	*/
    always @(posedge clk or negedge rstn) 
		begin 
			if ( !rstn )
				mdio_reg_addr <= 'd0;
			else if ( rx_cmd && cmd == ASCIIr )
				mdio_reg_addr <= { buffer[1][0], buffer[2][3:0] };
		end	
		
	/* set mdio_w_data_l and mdio_w_data_h	*/
    always @(posedge clk or negedge rstn) 
		begin 
			if ( !rstn )
				begin
					mdio_w_data_l <= 'd0;
					mdio_w_data_h <= 'd0;
				end
			else if ( rx_cmd &&  (cmd == ASCIIw  || cmd == ASCIIy || cmd == ASCIIz ) )
				begin
					mdio_w_data_h <= { buffer[1][3:0], buffer[2][3:0] };	
					mdio_w_data_l <= { buffer[3][3:0], buffer[4][3:0] };
				end
		end	
	
	// Channel Resets
    always @(posedge clk or negedge rstn) 
		begin 
			if ( !rstn )
				begin
					c_reg[0] <= 'hff;
					c_reg[1] <= 'hff;
					c_reg[2] <= 'hff;
					c_reg[3] <= 'hff;
				end
			else if ( rx_cmd && cmd == ASCIIc )
				begin
					c_reg[0] <= buffer[4][2:0];
					c_reg[1] <= buffer[3][2:0];
					c_reg[2] <= buffer[2][2:0];
					c_reg[3] <= buffer[1][2:0];
				end
		end	
		
	assign rx_pcs_rst[0] = c_reg[0][0];
	assign rx_serdes_rst[0] = c_reg[0][1];
	assign tx_pcs_rst[0]= c_reg[0][2];
	
	assign rx_pcs_rst[1] = c_reg[1][0];
	assign rx_serdes_rst[1] = c_reg[1][1];
	assign tx_pcs_rst[1]= c_reg[1][2];
	
	assign rx_pcs_rst[2] = c_reg[2][0];
	assign rx_serdes_rst[2] = c_reg[2][1];
	assign tx_pcs_rst[2]= c_reg[2][2];
	
	assign rx_pcs_rst[3] = c_reg[3][0];
	assign rx_serdes_rst[3] = c_reg[3][1];
	assign tx_pcs_rst[3]= c_reg[3][2];

	/* DCU resets */
    always @(posedge clk or negedge rstn) 
		begin 
			if ( !rstn )
				begin
					u_reg[0] <= 'hff;
					u_reg[1] <= 'hff;
				end
			else if ( rx_cmd && cmd == ASCIIu )
				begin
					u_reg[0] <= buffer[2][2:0];
					u_reg[1] <= buffer[1][2:0];
				end
		end	
		
	// DCU0 Reset assignments
	assign pcs_rst_dual[0] = u_reg[0][2];
	assign serdes_rst_dual[0] = u_reg[0][1];
	assign tx_serdes_rst[0] = u_reg[0][0];
	
	// DCU1 Reset assignments
	assign pcs_rst_dual[1] = u_reg[1][2];
	assign serdes_rst_dual[1] = u_reg[1][1];
	assign tx_serdes_rst[1] = u_reg[1][0];
	
	/* X control */
    always @(posedge clk or negedge rstn) 
		begin 
			if ( !rstn )
				begin
					x_reg[0] <= 'hff;
					x_reg[1] <= 'hff;
					x_reg[2] <= 'hff;
					x_reg[3] <= 'hff;

				end
			else if ( rx_cmd && cmd == ASCIIx )
				begin
					x_reg[0] <= buffer[4][1:0];
					x_reg[1] <= buffer[3][1:0];
					x_reg[2] <= buffer[2][1:0];
					x_reg[3] <= buffer[1][1:0];

				end
		end	

	assign mac_reset[0] = x_reg[0][0];
	assign phy_resetn[0] = ~x_reg[0][1];

	assign mac_reset[1] = x_reg[1][0];
	assign phy_resetn[1] = ~x_reg[1][1];
	
	assign mac_reset[2] = x_reg[2][0];
	assign phy_resetn[2] = ~x_reg[2][1];
	
	assign mac_reset[3] = x_reg[3][0];
	assign phy_resetn[3] = ~x_reg[3][1];
	
	
	/* mdio_mux_sel */
    always @(posedge clk or negedge rstn) 
		begin 
			if ( !rstn )
				mdio_mux_sel <= 'h0;
			else if ( rx_cmd && cmd == ASCIIm )
				mdio_mux_sel <= buffer[1][1:0];
		end	
		
	/* transmit custom packet */
    always @(posedge clk or negedge rstn) 
		begin 
			if ( !rstn )
				tx_custom <= 1'b0;
			else if ( rx_cmd && cmd == ASCIIt )
				tx_custom <= 1'b1;
			else
				tx_custom <= 1'b0;			
		end	
	
	/* FIFO logic */
    always @(posedge clk or negedge rstn) 
		begin 
			if ( !rstn )
				fifo_we <= 1'b0;
			else if ( cont_state == S2 )
				fifo_we <= 1'b1;
			else 
				fifo_we <= 1'b0;
		end	

		
   always @(posedge clk or negedge rstn) 
		begin 
			if ( !rstn )
				read_fifo_d_o <= 0;
			else if ( cont_state == S2 && cmd == ASCIIp )	// pcs status
				read_fifo_d_o <= { 1'b0, pcs_s };
			else if ( cont_state == S2 && cmd == ASCIIl )	// link status
				read_fifo_d_o <= { 3'b000, link_s };			
		end

	/*
	*	capture the cmd and buffer
	*	rx_cmd is a one shot at the end that triggers the state machine
	*/
	assign rx_cmd = i2c_rx_done;
	
    always @(posedge clk or negedge rstn) 
		begin 
			if ( !rstn )
				cmd <= 7'h0;
			else if (  i2c_rx_we && cnt == 4'h0 )
				cmd <= i2c_d_in;
		end	
	
    always @(posedge clk or negedge rstn)
		begin 
			if ( !rstn )
				begin
					for (i=1; i<=BUFFER_SZ; i=i+1)
						begin
							buffer[i] <= 'h0;
						end
				end
			else if (  i2c_rx_we && cnt > 0 && cnt <= BUFFER_SZ )
				buffer[cnt] <= i2c_d_in;
		end
		
	/*
	* 	counter for I2c rx buffer.  
	*/
    always @(posedge clk or negedge rstn) 
		begin 
			if ( !rstn )
				cnt <= 'h0;
			else if (i2c_rx_done)
				cnt <= 'h0;	
			else if (i2c_rx_we  )
				cnt <= cnt + 1;
		end


endmodule