-------------------------------------------------------------------------                                                             --------  OpenCores ATA/ATAPI-5 Host Controller                      --------  PIO Timing Controller (common for all OCIDEC cores)        --------                                                             --------  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.                                 --------                                                             --------------------------------------------------------------------------- rev.: 1.0 march  7th, 2001. Initial release-- rev.: 1.1 July  11th, 2001. Changed 'igo' & 'hold_go' signal generation.------  CVS Log----  $Id: atahost_pio_tctrl.vhd,v 1.1 2002/02/18 14:29:38 rherveille Exp $----  $Date: 2002/02/18 14:29:38 $--  $Revision: 1.1 $--  $Author: rherveille $--  $Locker:  $--  $State: Exp $---- Change History:--               $Log: atahost_pio_tctrl.vhd,v $--               Revision 1.1  2002/02/18 14:29:38  rherveille--               renamed 'atahost.vhd' to 'atahost_top.vhd'--               renamed 'controller.vhd' to 'atahost_controller.vhd'--               renamed 'pio_tctrl.vhd' to 'atahost_pio_tctrl.vhd'--               broke-up 'counter.vhd' into 'ud_cnt.vhd' and 'ro_cnt.vhd'--               changed resD input to generic RESD in ud_cnt.vhd--               changed ID input to generic ID in ro_cnt.vhd--               changed core to reflect changes in ro_cnt.vhd--               removed references to 'count' library--               changed IO names--               added disclaimer--               added CVS log--               moved registers and wishbone signals into 'atahost_wb_slave.vhd'--               core is now equivalent to verilog version------------------------------------- PIO Timing controller ----------------------------------- Timing	PIO mode transfers------------------------------------------------ T0:	cycle time-- T1:	address valid to DIOR-/DIOW--- T2:	DIOR-/DIOW- pulse width-- T2i:	DIOR-/DIOW- recovery time-- T3:	DIOW- data setup-- T4:	DIOW- data hold-- T5:	DIOR- data setup-- T6:	DIOR- data hold-- T9:	address hold from DIOR-/DIOW- negated-- Trd:	Read data valid to IORDY asserted-- Ta:	IORDY setup time-- Tb:	IORDY pulse width---- Transfer sequence------------------------------------ 1)	set address (DA, CS0-, CS1-)-- 2)	wait for T1-- 3)	assert DIOR-/DIOW---	   when write action present Data (timing spec. T3 always honored), enable output enable-signal-- 4)	wait for T2-- 5)	check IORDY--	   when not IORDY goto 5-- 	  when IORDY negate DIOW-/DIOR-, latch data (if read action)--    when write, hold data for T4, disable output-enable signal-- 6)	wait end_of_cycle_time. This is T2i or T9 or (T0-T1-T2) whichever takes the longest-- 7)	start new cyclelibrary ieee;use ieee.std_logic_1164.all;use ieee.std_logic_arith.all;entity atahost_pio_tctrl is	generic(		TWIDTH : natural := 8;                   -- counter width		-- PIO mode 0 settings (@100MHz clock)		PIO_mode0_T1 : natural := 6;             -- 70ns		PIO_mode0_T2 : natural := 28;            -- 290ns		PIO_mode0_T4 : natural := 2;             -- 30ns		PIO_mode0_Teoc : natural := 23           -- 240ns ==> T0 - T1 - T2 = 600 - 70 - 290 = 240	);	port(		clk    : in std_logic;                   -- master clock		nReset : in std_logic;                   -- asynchronous active low reset		rst    : in std_logic;                   -- synchronous active high reset		-- timing/control register settings		IORDY_en : in std_logic;                 -- use IORDY (or not)		T1   : in unsigned(TWIDTH -1 downto 0);  -- T1 time (in clk-ticks)		T2   : in unsigned(TWIDTH -1 downto 0);  -- T2 time (in clk-ticks)		T4   : in unsigned(TWIDTH -1 downto 0);  -- T4 time (in clk-ticks)		Teoc : in unsigned(TWIDTH -1 downto 0);  -- end of cycle time		-- control signals		go : in std_logic;                       -- PIO controller selected (strobe signal)		we : in std_logic;                       -- write enable signal. '0'=read from device, '1'=write to device		-- return signals		oe    : buffer std_logic;                -- output enable signal		done  : out std_logic;                   -- finished cycle		dstrb : out std_logic;                   -- data strobe, latch data (during read)		-- ATA signals		DIOR,                                    -- IOread signal, active high		DIOW  : buffer std_logic;                -- IOwrite signal, active high		IORDY : in std_logic                     -- IORDY signal	);end entity atahost_pio_tctrl;architecture structural of atahost_pio_tctrl is	component ro_cnt is	generic(		SIZE : natural := 8;		UD   : std_logic := '0'; -- default count down		ID   : natural := 0      -- initial data after reset	);	port(		clk    : in  std_logic;                  -- master clock		nReset : in  std_logic := '1';           -- asynchronous active low reset		rst    : in  std_logic := '0';           -- synchronous active high reset		cnt_en : in  std_logic := '1';           -- count enable		go     : in  std_logic;                  -- load counter and start sequence		done   : out std_logic;                  -- done counting		d      : in  unsigned(SIZE -1 downto 0); -- load counter value		q      : out unsigned(SIZE -1 downto 0)  -- current counter value	);	end component ro_cnt;	signal T1done, T2done, T4done, Teoc_done, IORDY_done : std_logic;	signal busy, hold_go, igo, hT2done : std_logic;begin	-- generate internal go strobe	-- strecht go until ready for new cycle	process(clk, nReset)	begin		if (nReset = '0') then			busy <= '0';			hold_go <= '0';		elsif (clk'event and clk = '1') then			if (rst = '1') then				busy <= '0';				hold_go <= '0';			else				busy <= (igo or busy) and not Teoc_done;				hold_go <= (go or (hold_go and busy)) and not igo;			end if;		end if;	end process;	igo <= (go or hold_go) and not busy;	-- 1)	hookup T1 counter	t1_cnt : ro_cnt 		generic map (			SIZE => TWIDTH,			UD   => '0',			ID   => PIO_mode0_T1		)		port map (			clk => clk,			nReset => nReset,			rst => rst,			go => igo,			D => T1,			done => T1done		);	-- 2)	set (and reset) DIOR-/DIOW-, set output-enable when writing to device	T2proc: process(clk, nReset)	begin		if (nReset = '0') then			DIOR <= '0';			DIOW <= '0';			oe   <= '0';		elsif (clk'event and clk = '1') then			if (rst = '1') then				DIOR <= '0';				DIOW <= '0';				oe   <= '0';			else				DIOR <= (not we and T1done) or (DIOR and not IORDY_done);				DIOW <= (    we and T1done) or (DIOW and not IORDY_done);				oe   <= ( (we and igo) or oe) and not T4done; -- negate oe when t4-done			end if;		end if;	end process T2proc;	-- 3)	hookup T2 counter	t2_cnt : ro_cnt 		generic map (			SIZE => TWIDTH,			UD   => '0',			ID   => PIO_mode0_T2		)		port map (			clk => clk,			nReset => nReset,			rst => rst,			go => T1done,			D => T2,			done => T2done		);	-- 4)	check IORDY (if used), generate release_DIOR-/DIOW- signal (ie negate DIOR-/DIOW-)	-- hold T2done	gen_hT2done: process(clk, nReset)	begin		if (nReset = '0') then			hT2done <= '0';		elsif (clk'event and clk = '1') then			if (rst = '1') then				hT2done <= '0';			else				hT2done <= (T2done or hT2done) and not IORDY_done;			end if;		end if;	end process gen_hT2done;	IORDY_done <= (T2done or hT2done) and (IORDY or not IORDY_en);	-- generate datastrobe, capture data at rising DIOR- edge	gen_dstrb: process(clk)	begin		if (clk'event and clk = '1') then			dstrb <= IORDY_done;		end if;	end process gen_dstrb;	-- hookup data hold counter	dhold_cnt : ro_cnt 		generic map (			SIZE => TWIDTH,			UD   => '0',			ID   => PIO_mode0_T4		)		port map (			clk => clk,			nReset => nReset,			rst => rst,			go => IORDY_done,			D => T4,			done => T4done		);	done <= T4done; -- placing done here provides the fastest return possible,                       -- while still guaranteeing data and address hold-times	-- 5)	hookup end_of_cycle counter	eoc_cnt : ro_cnt 		generic map (			SIZE => TWIDTH,			UD   => '0',			ID   => PIO_mode0_Teoc		)		port map (			clk => clk,			nReset => nReset,			rst => rst,			go => IORDY_done,			D => Teoc,			done => Teoc_done		);end architecture structural;