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/////////////////////////////////////////////////////////////////////
////                                                             ////
////  OCIDEC-1 ATA/ATAPI-5 Host Controller                       ////
////  PIO Controller                                             ////
////                                                             ////
////  Author: Richard Herveille                                  ////
////          richard@asics.ws                                   ////
////          www.asics.ws                                       ////
////                                                             ////
/////////////////////////////////////////////////////////////////////
////                                                             ////
//// Copyright (C) 2001, 2002 Richard Herveille                  ////
////                          richard@asics.ws                   ////
////                                                             ////
//// This source file may be used and distributed without        ////
//// restriction provided that this copyright statement is not   ////
//// removed from the file and that any derivative work contains ////
//// the original copyright notice and the associated disclaimer.////
////                                                             ////
////     THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY     ////
//// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED   ////
//// TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS   ////
//// FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL THE AUTHOR      ////
//// OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,         ////
//// INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES    ////
//// (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE   ////
//// GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR        ////
//// BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF  ////
//// LIABILITY, WHETHER IN  CONTRACT, STRICT LIABILITY, OR TORT  ////
//// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT  ////
//// OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE         ////
//// POSSIBILITY OF SUCH DAMAGE.                                 ////
////                                                             ////
/////////////////////////////////////////////////////////////////////
 
//  CVS Log
//
//  $Id: atahost_controller.v,v 1.4 2002-05-19 06:04:22 rherveille Exp $
//
//  $Date: 2002-05-19 06:04:22 $
//  $Revision: 1.4 $
//  $Author: rherveille $
//  $Locker:  $
//  $State: Exp $
//
// Change History:
//               rev.: 1.0  june  28th, 2001. Initial Verilog release
//               rev.: 1.1  July   3rd, 2001. Rewrote "IORDY" and "INTRQ" capture section.
//               rev.: 1.2  July   9th, 2001. Added "timescale". Undid "IORDY & INTRQ" rewrite.
//               rev.: 1.3  July  11th, 2001. Changed PIOreq & PIOack generation (made them synchronous). 
//               rev.: 1.4  July  26th, 2001. Fixed non-blocking assignments.
//
//               $Log: not supported by cvs2svn $
//               Revision 1.2  2002/02/16 10:42:17  rherveille
//               Added disclaimer
//               Added CVS information
//               Changed core for new internal counter libraries (synthesis fixes).
//
//
//
 
`include "timescale.v"
 
module atahost_controller (clk, nReset, rst, irq, IDEctrl_rst, IDEctrl_IDEen, 
			PIO_cmdport_T1, PIO_cmdport_T2, PIO_cmdport_T4, PIO_cmdport_Teoc, PIO_cmdport_IORDYen, 
			PIOreq, PIOack, PIOa, PIOd, PIOq, PIOwe, 
			RESETn, DDi, DDo, DDoe, DA, CS0n, CS1n, DIORn, DIOWn, IORDY, INTRQ);
	//
	// parameter declarations
	//
	parameter TWIDTH = 8;              // counter width
	// PIO mode 0 timing settings @100MHz master clock
	parameter PIO_mode0_T1   = 6;      // 70ns
	parameter PIO_mode0_T2   = 28;     // 290ns
	parameter PIO_mode0_T4   = 2;      // 30ns
	parameter PIO_mode0_Teoc = 23;     // 240ns ==> T0 - T1 - T2 = 600 - 70 - 290 = 240
	//
	// inputs & outputs
	//
	input  clk; //master clock
	input  nReset; // asynchronous active low reset
	input  rst; // synchronous active high reset
 
	output irq; // interrupt request signal
	reg irq;
 
	// control bits
	input  IDEctrl_rst;
	input  IDEctrl_IDEen;
 
	// PIO timing registers
	input  [7:0] PIO_cmdport_T1;
	input  [7:0] PIO_cmdport_T2;
	input  [7:0] PIO_cmdport_T4;
	input  [7:0] PIO_cmdport_Teoc;
	input        PIO_cmdport_IORDYen;
 
	// PIO control signals
	input         PIOreq; // PIO transfer request
	output        PIOack; // PIO transfer ended
	input  [ 3:0] PIOa;   // PIO address
	input  [15:0] PIOd;   // PIO data in
	output [15:0] PIOq;   // PIO data out
	input         PIOwe;  // PIO direction  bit. 1'b1==write, 1'b0==read
 
	reg [15:0] PIOq;
	reg PIOack;
 
	// ATA signals
	output        RESETn;
	input  [15:0] DDi;
	output [15:0] DDo;
	output        DDoe;
	output [ 2:0] DA;
	output        CS0n;
	output        CS1n;
	output        DIORn;
	output        DIOWn;
	input         IORDY;
	input         INTRQ;
 
	reg        RESETn;
	reg [15:0] DDo;
	reg        DDoe;
	reg [ 2:0] DA;
	reg        CS0n;
	reg        CS1n;
	reg        DIORn;
	reg        DIOWn;
 
	//
	// Variable declarations
	//
 
	reg dPIOreq;
	reg PIOgo;   // start PIO timing controller
	wire PIOdone; // PIO timing controller done
 
	// PIO signals
	wire PIOdior, PIOdiow;
	wire PIOoe;
 
	// Timing settings
	wire              dstrb;
	wire [TWIDTH-1:0] T1, T2, T4, Teoc;
	wire              IORDYen;
 
	// synchronized ATA inputs
	reg sIORDY;
 
	//
	// Module body
	//
 
 
	// synchronize incoming signals
	reg cIORDY;                               // capture IORDY
	reg cINTRQ;                               // capture INTRQ
 
	always@(posedge clk)
	begin : synch_incoming
		cIORDY <= #1 IORDY;
		cINTRQ <= #1 INTRQ;
 
		sIORDY <= #1 cIORDY;
		irq    <= #1 cINTRQ;
	end
 
	// generate ATA signals
	always@(posedge clk or negedge nReset)
		if (~nReset)
			begin
				RESETn <= #1 1'b0;
				DIORn  <= #1 1'b1;
				DIOWn  <= #1 1'b1;
				DA     <= #1 0;
				CS0n	  <= #1 1'b1;
				CS1n	  <= #1 1'b1;
				DDo    <= #1 0;
				DDoe   <= #1 1'b0;
			end
		else if (rst)
			begin
				RESETn <= #1 1'b0;
				DIORn  <= #1 1'b1;
				DIOWn  <= #1 1'b1;
				DA     <= #1 0;
				CS0n	  <= #1 1'b1;
				CS1n	  <= #1 1'b1;
				DDo    <= #1 0;
				DDoe   <= #1 1'b0;
			end
		else
			begin
				RESETn <= #1 !IDEctrl_rst;
				DA     <= #1 PIOa[2:0];
				CS0n   <= #1 !( !PIOa[3] & PIOreq); // CS0 asserted when A(3) = '0'
				CS1n   <= #1 !(  PIOa[3] & PIOreq); // CS1 asserted when A(3) = '1'
 
				DDo    <= #1 PIOd;
				DDoe   <= #1 PIOoe;
				DIORn  <= #1 !PIOdior;
				DIOWn  <= #1 !PIOdiow;
			end
 
 
	//
	//////////////////////////
	// PIO transfer control //
	//////////////////////////
	//
	// capture ATA data for PIO access
	always@(posedge clk)
		if (dstrb)
			PIOq <= #1 DDi;
 
	// generate PIOgo signal
	always @(posedge clk or negedge nReset)
		if (~nReset)
			begin
				dPIOreq <= #1 1'b0;
				PIOgo   <= #1 1'b0;
			end
		else if (rst)
			begin
				dPIOreq <= #1 1'b0;
				PIOgo   <= #1 1'b0;
			end
		else
			begin
				dPIOreq <= #1 PIOreq & !PIOack;
				PIOgo   <= #1 (PIOreq & !dPIOreq) & IDEctrl_IDEen;
			end
 
	// set Timing signals
	assign T1      = PIO_cmdport_T1;
	assign T2      = PIO_cmdport_T2;
	assign T4      = PIO_cmdport_T4;
	assign Teoc    = PIO_cmdport_Teoc;
	assign IORDYen = PIO_cmdport_IORDYen;
 
	// hookup timing controller
	atahost_pio_tctrl #(TWIDTH, PIO_mode0_T1, PIO_mode0_T2, PIO_mode0_T4, PIO_mode0_Teoc)
		PIO_timing_controller (
			.clk(clk),
			.nReset(nReset),
			.rst(rst),
			.IORDY_en(IORDYen),
			.T1(T1),
			.T2(T2),
			.T4(T4),
			.Teoc(Teoc),
			.go(PIOgo),
			.we(PIOwe),
			.oe(PIOoe),
			.done(PIOdone),
			.dstrb(dstrb),
			.DIOR(PIOdior),
			.DIOW(PIOdiow),
			.IORDY(sIORDY)
		);
 
	always@(posedge clk)
		PIOack <= #1 PIOdone | (PIOreq & !IDEctrl_IDEen); // acknowledge when done or when IDE not enabled (discard request)
 
endmodule