Add option to not flatten hierarchy

Vivado by default tries to flatten the module hierarchy to improve
placement and timing. However this makes debugging timing issues
really hard as the net names in the timing report can be pretty
bogus.

This adds a generic that can be used to control attributes to stop
vivado from flattening the main core components. The resulting design
will have worst timing overall but it will be easier to understand
what the worst timing path are and address them.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
jtag-port
Benjamin Herrenschmidt 5 years ago
parent 48f260761b
commit d2762e70e5

@ -8,7 +8,8 @@ use work.wishbone_types.all;

entity core is
generic (
SIM : boolean := false
SIM : boolean := false;
DISABLE_FLATTEN : boolean := false
);
port (
clk : in std_logic;
@ -93,6 +94,29 @@ architecture behave of core is
-- Debug status
signal dbg_core_is_stopped: std_ulogic;

function keep_h(disable : boolean) return string is
begin
if disable then
return "yes";
else
return "no";
end if;
end function;
attribute keep_hierarchy : string;
attribute keep_hierarchy of fetch1_0 : label is keep_h(DISABLE_FLATTEN);
attribute keep_hierarchy of icache_0 : label is keep_h(DISABLE_FLATTEN);
attribute keep_hierarchy of fetch2_0 : label is keep_h(DISABLE_FLATTEN);
attribute keep_hierarchy of decode1_0 : label is keep_h(DISABLE_FLATTEN);
attribute keep_hierarchy of decode2_0 : label is keep_h(DISABLE_FLATTEN);
attribute keep_hierarchy of register_file_0 : label is keep_h(DISABLE_FLATTEN);
attribute keep_hierarchy of cr_file_0 : label is keep_h(DISABLE_FLATTEN);
attribute keep_hierarchy of execute1_0 : label is keep_h(DISABLE_FLATTEN);
attribute keep_hierarchy of multiply_0 : label is keep_h(DISABLE_FLATTEN);
attribute keep_hierarchy of divider_0 : label is keep_h(DISABLE_FLATTEN);
attribute keep_hierarchy of loadstore1_0 : label is keep_h(DISABLE_FLATTEN);
attribute keep_hierarchy of dcache_0 : label is keep_h(DISABLE_FLATTEN);
attribute keep_hierarchy of writeback_0 : label is keep_h(DISABLE_FLATTEN);
attribute keep_hierarchy of debug_0 : label is keep_h(DISABLE_FLATTEN);
begin

core_rst <= dbg_core_rst or rst;

@ -7,7 +7,8 @@ entity toplevel is
RAM_INIT_FILE : string := "firmware.hex";
RESET_LOW : boolean := true;
CLK_INPUT : positive := 100000000;
CLK_FREQUENCY : positive := 100000000
CLK_FREQUENCY : positive := 100000000;
DISABLE_FLATTEN_CORE : boolean := false
);
port(
ext_clk : in std_ulogic;
@ -62,7 +63,8 @@ begin
MEMORY_SIZE => MEMORY_SIZE,
RAM_INIT_FILE => RAM_INIT_FILE,
RESET_LOW => RESET_LOW,
SIM => false
SIM => false,
DISABLE_FLATTEN_CORE => DISABLE_FLATTEN_CORE
)
port map (
system_clk => system_clk,

@ -93,6 +93,7 @@ targets:
- ram_init_file
- clk_input
- clk_frequency
- disable_flatten_core
tools:
vivado: {part : xc7a100tcsg324-1}
toplevel : toplevel
@ -105,6 +106,7 @@ targets:
- ram_init_file
- clk_input
- clk_frequency
- disable_flatten_core
tools:
vivado: {part : xc7a200tsbg484-1}
toplevel : toplevel
@ -117,6 +119,7 @@ targets:
- ram_init_file
- clk_input
- clk_frequency
- disable_flatten_core
tools:
vivado: {part : xc7a35ticsg324-1L}
toplevel : toplevel
@ -129,6 +132,7 @@ targets:
- ram_init_file
- clk_input
- clk_frequency
- disable_flatten_core
tools:
vivado: {part : xc7a100ticsg324-1L}
toplevel : toplevel
@ -142,6 +146,7 @@ targets:
- reset_low=false
- clk_input=12000000
- clk_frequency
- disable_flatten_core
tools:
vivado: {part : xc7a35tcpg236-1}
toplevel : toplevel
@ -179,3 +184,9 @@ parameters:
description : Generated system clock frequency in HZ (for top-generic based boards)
paramtype : generic
default : 50000000

disable_flatten_core:
datatype : bool
description : Prevent Vivado from flattening the main core components
paramtype : generic
default : false

@ -17,7 +17,8 @@ entity soc is
MEMORY_SIZE : positive;
RAM_INIT_FILE : string;
RESET_LOW : boolean;
SIM : boolean
SIM : boolean;
DISABLE_FLATTEN_CORE : boolean := false
);
port(
rst : in std_ulogic;
@ -76,7 +77,8 @@ begin
-- Processor core
processor: entity work.core
generic map(
SIM => SIM
SIM => SIM,
DISABLE_FLATTEN => DISABLE_FLATTEN_CORE
)
port map(
clk => system_clk,

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