atahost_dma_actrl.vhd

最新的ATA-六总线协议源代码参考

			end if;
		end process gen_Tfw;

		-- transmit data part
		gen_writed_pipe:process(clk)
		begin
			if (clk'event and clk = '1') then
				if (TxRd = '1') then                              -- reload registers
					if (BeLeC = '1') then                           -- Do big<->little endian conversion
						writeDfw(15 downto 8) <= TxbufQ( 7 downto  0); -- TxbufQ = data from transmit buffer
						writeDfw( 7 downto 0) <= TxbufQ(15 downto  8);
						writeDlw(15 downto 8) <= TxbufQ(23 downto 16);
						writeDlw( 7 downto 0) <= TxbufQ(31 downto 24);
					else                                              -- don't do big<->little endian conversion
						writeDfw <= TxbufQ(31 downto 16);
						writeDlw <= TxbufQ(15 downto 0);
					end if;
				elsif (wr_dstrb = '1') then                          -- next word to transfer
					writeDfw <= writeDlw;
				end if;
			end if;
		end process gen_writed_pipe;
		DDo <= writeDfw;                                       -- assign DMA data out

		-- generate transmit register read request
		gen_Tx_rreq: process(clk, nReset)
		begin
			if (nReset = '0') then
				TxRd <= '0';
			elsif (clk'event and clk = '1') then
				if (rst = '1') then
					TxRd <= '0';
				else
					TxRd <= go and DMActrl_dir;
				end if;
			end if;
		end process gen_Tx_rreq;
		
		-- receive
		gen_readd_pipe:process(clk)
		begin
			if (clk'event and clk = '1') then
				if (rd_dstrb = '1') then

					readDfw <= readDlw;                   -- shift previous read word to msb
					if (BeLeC = '1') then                 -- swap bytes
						readDlw(15 downto 8) <= DDi( 7 downto 0);
						readDlw( 7 downto 0) <= DDi(15 downto 8);
					else                                  -- don't swap bytes
						readDlw <= DDi;
					end if;
				end if;
			end if;
		end process gen_readd_pipe;
		-- RxD = data to receive buffer
		RxbufD <= (readDfw & readDlw) when (BeLeC = '0') else (readDlw & readDfw);

		-- generate receive register write request
		gen_Rx_wreq: process(clk, nReset)
		begin
			if (nReset = '0') then
				RxWr <= '0';
			elsif (clk'event and clk = '1') then
				if (rst = '1') then
					RxWr <= '0';
				else
					RxWr <= not Tfw and rd_dstrb;
				end if;
			end if;
		end process gen_Rx_wreq;
	end block gen_DMA_sigs;


	--
	-- Hookup DMA read / write buffers
	--
	gen_DMAbuf: block
		signal DMArst : std_logic;
		signal RxRd, TxWr : std_logic;
		signal iRxEmpty : std_logic;
	begin
		-- generate DMA reset signal
		DMArst <= rst or IDEctrl_rst;

		Txbuf: atahost_reg_buf
			generic map (WIDTH => 32)
			port map (
				clk    => clk,
				nReset => nReset,
				rst    => DMArst,
				D      => TxD,
				Q      => TxbufQ, 
				rd     => TxRd,
				wr     => TxWr,
				valid  =>	TxFull
			);

		Rxbuf: atahost_fifo
			generic map (DEPTH => 7, SIZE => 32)
			port map (
				clk    => clk,
				nReset => nReset,
				rst    => DMArst,
				D      => RxbufD,
				Q      => RxQ,
				rreq   => RxRd,
				wreq   => RxWr,
				empty  =>	iRxEmpty,
				full   => RxFull
			);

		RxEmpty <= iRxEmpty; -- avoid 'cannot associate OUT port with BUFFER port' error

		--
		-- generate DMA buffer access signals
		--
		RxRd <= sel and not we and not RxEmpty;
		TxWr <= sel and     we and not TxFull;

		ack  <= RxRd or TxWr; -- DMA buffer access acknowledge
	end block gen_DMAbuf;

	--
	-- generate request signal for external DMA engine
	--
	gen_DMA_req: block
		signal hgo : std_logic;
		signal iDMA_req : std_logic;
		signal request : std_logic;
	begin
		-- generate hold-go
		gen_hgo : process(clk, nReset)
		begin
			if (nReset = '0') then
				hgo <= '0';
			elsif (clk'event and clk = '1') then
				if (rst = '1') then
					hgo <= '0';
				else
					hgo <= go or (hgo and not (wr_dstrb and not Tfw) and DMActrl_dir);
				end if;
			end if;
		end process gen_hgo;

		request <= (DMActrl_dir and DMARQ and not TxFull and not hgo) or not RxEmpty;
		process(clk, nReset)
		begin
			if (nReset = '0') then
				iDMA_req <= '0';
			elsif (clk'event and clk = '1') then
				if (rst = '1') then
					iDMA_req <= '0';
				else
					iDMA_req <= DMActrl_DMAen and not DMA_ack and (request or iDMA_req);
--				DMA_req <= (DMActrl_DMAen and DMActrl_dir and DMARQ and not TxFull and not hgo) or not RxEmpty;
				end if;
			end if;
		end process;
		DMA_req <= iDMA_req;
	end block gen_DMA_req;


	--
	-- DMA timing controller
	--
	DMA_timing_ctrl: block
		signal Tm, Td, Teoc, Tdmack_ext : unsigned(TWIDTH -1 downto 0);
		signal dTfw, igo : std_logic;
	begin
		--
		-- generate internal GO signal
		--
		gen_igo : process(clk, nReset)
		begin
			if (nReset = '0') then
				igo  <= '0';
				dTfw <= '0';
			elsif (clk'event and clk = '1') then
				if (rst = '1') then
					igo  <= '0';
					dTfw <= '0';
				else
					igo  <= go or (not Tfw and dTfw);
					dTfw <= Tfw;
				end if;
			end if;
		end process gen_igo;

		--
		-- select timing settings for the addressed device
		--
		sel_dev_t: process(clk)
		begin
			if (clk'event and clk = '1') then
				if (SelDev = '1') then                      -- device1 selected
					Tm   <= dev1_Tm;
					Td   <= dev1_Td;
					Teoc <= dev1_Teoc;
				else                                        -- device0 selected
					Tm   <= dev0_Tm;
					Td   <= dev0_Td;
					Teoc <= dev0_Teoc;
				end if;
			end if;
		end process sel_dev_t;

		--
		-- hookup timing controller
		--
		DMA_timing_ctrl: atahost_dma_tctrl 
			generic map (
				TWIDTH => TWIDTH, 
				DMA_mode0_Tm   => DMA_mode0_Tm,
				DMA_mode0_Td   => DMA_mode0_Td,
				DMA_mode0_Teoc => DMA_mode0_Teoc
			)
			port map (
				clk    => clk,
				nReset => nReset,
				rst    => rst,
				Tm     => Tm,
				Td     => Td,
				Teoc   => Teoc, 
				go     => igo,
				we     => DMActrl_dir,
				done   => Tdone,
				dstrb  => dstrb,
				DIOR   => dior,
				DIOW   => diow
			);

		done <= Tdone and not Tfw;             -- done transfering last word
		rd_dstrb <= dstrb and not DMActrl_dir; -- read data strobe
		wr_dstrb <= dstrb and     DMActrl_dir; -- write data strobe
	end block DMA_timing_ctrl;
		
end architecture structural;