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ee52fd4d80
This adds a simple bus that can be mastered from an external system via JTAG, which will be used to hookup various debug modules. It's loosely based on the RiscV model (hence the DMI name). The module currently only supports hooking up to a Xilinx BSCANE2 but it shouldn't be too hard to adapt it to support different TAPs if necessary. The JTAG protocol proper is not exactly the RiscV one at this point, though I might still change it. This comes with some sim variants of Xilinx BSCANE2 and BUFG and a test bench. Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
31 lines
751 B
VHDL
31 lines
751 B
VHDL
-- Dummy/empty DMI interface to make toplevel happy on unsupported FPGAs
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library ieee;
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use ieee.std_logic_1164.all;
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library work;
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use work.wishbone_types.all;
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entity dmi_dtm is
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generic(ABITS : INTEGER:=8;
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DBITS : INTEGER:=32);
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port(sys_clk : in std_ulogic;
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sys_reset : in std_ulogic;
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dmi_addr : out std_ulogic_vector(ABITS - 1 downto 0);
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dmi_din : in std_ulogic_vector(DBITS - 1 downto 0);
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dmi_dout : out std_ulogic_vector(DBITS - 1 downto 0);
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dmi_req : out std_ulogic;
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dmi_wr : out std_ulogic;
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dmi_ack : in std_ulogic
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);
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end entity dmi_dtm;
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architecture behaviour of dmi_dtm is
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dmi_addr <= (others => '0');
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dmi_dout <= (others => '0');
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dmi_req <= '0';
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dmi_wr <= '0';
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end architecture behaviour;
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