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Improve PLL/MMCM clocks configuration

Browse Source 
We can now pass both the input clock and target clock frequency
via generics. Add support for both 50Mhz and 100Mhz target freqs
for both cases.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
pull/77/head
Benjamin Herrenschmidt 5 years ago
parent 5f28109957
commit 9961d70dfb
4 changed files with 176 additions and 76 deletions
Show Stats Download Patch File Download Diff File

74
fpga/clk_gen_mcmm.vhd
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@ -6,7 +6,9 @@ use UNISIM.vcomponents.all;


entity clock_generator is entity clock_generator is
generic ( generic (
clk_period_hz : positive := 12000000); CLK_INPUT_HZ : positive := 12000000;
CLK_OUTPUT_HZ : positive := 50000000
);
port ( port (
ext_clk : in std_logic; ext_clk : in std_logic;
pll_rst_in : in std_logic; pll_rst_in : in std_logic;
@ -22,28 +24,66 @@ architecture rtl of clock_generator is
clkfbout_mult : real range 2.0 to 64.0; clkfbout_mult : real range 2.0 to 64.0;
clkout_divide : real range 1.0 to 128.0; clkout_divide : real range 1.0 to 128.0;
divclk_divide : integer range 1 to 106; divclk_divide : integer range 1 to 106;
force_rst : std_ulogic;
end record; end record;


function gen_pll_settings ( function gen_pll_settings (
constant freq_hz : positive) constant input_hz : positive;
constant output_hz : positive)
return pll_settings_t is return pll_settings_t is

constant bad_settings : pll_settings_t :=
(clkin_period => 0.0,
clkfbout_mult => 2.0,
clkout_divide => 1.0,
divclk_divide => 1,
force_rst => '1');
begin begin
if freq_hz = 100000000 then case input_hz is
return (clkin_period => 10.0, when 100000000 =>
clkfbout_mult => 16.0, case output_hz is
clkout_divide => 32.0, when 100000000 =>
divclk_divide => 1); return (clkin_period => 10.0,
elsif freq_hz = 12000000 then clkfbout_mult => 16.0,
return (clkin_period => 83.33, clkout_divide => 16.0,
clkfbout_mult => 50.0, divclk_divide => 1,
clkout_divide => 12.0, force_rst => '0');
divclk_divide => 1); when 50000000 =>
else return (clkin_period => 10.0,
report "Unsupported input frequency" severity failure; clkfbout_mult => 16.0,
end if; clkout_divide => 32.0,
divclk_divide => 1,
force_rst => '0');
when others =>
report "Unsupported output frequency" severity failure;
return bad_settings;
end case;
when 12000000 =>
case output_hz is
when 100000000 =>
return (clkin_period => 83.33,
clkfbout_mult => 50.0,
clkout_divide => 6.0,
divclk_divide => 1,
force_rst => '0');
when 50000000 =>
return (clkin_period => 83.33,
clkfbout_mult => 50.0,
clkout_divide => 12.0,
divclk_divide => 1,
force_rst => '0');
when others =>
report "Unsupported output frequency" severity failure;
return bad_settings;
end case;
when others =>
report "Unsupported input frequency" severity failure;
return bad_settings;
end case;
end function gen_pll_settings; end function gen_pll_settings;


constant pll_settings : pll_settings_t := gen_pll_settings(clk_period_hz); constant pll_settings : pll_settings_t := gen_pll_settings(clk_input_hz,
clk_output_hz);
begin begin
pll : MMCME2_BASE pll : MMCME2_BASE
generic map ( generic map (
@ -71,6 +111,6 @@ begin
CLKFBIN => clkfb, CLKFBIN => clkfb,
CLKIN1 => ext_clk, CLKIN1 => ext_clk,
PWRDWN => '0', PWRDWN => '0',
RST => pll_rst_in RST => pll_rst_in or pll_settings.force_rst
); );
end architecture rtl; end architecture rtl;

128
fpga/clk_gen_plle2.vhd
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@ -5,67 +5,89 @@ Library UNISIM;
use UNISIM.vcomponents.all; use UNISIM.vcomponents.all;


entity clock_generator is entity clock_generator is
generic ( generic (
clk_period_hz : positive := 100000000); CLK_INPUT_HZ : positive := 100000000;
port ( CLK_OUTPUT_HZ : positive := 100000000
ext_clk : in std_logic; );
pll_rst_in : in std_logic; port (
pll_clk_out : out std_logic; ext_clk : in std_logic;
pll_locked_out : out std_logic); pll_rst_in : in std_logic;
pll_clk_out : out std_logic;
pll_locked_out : out std_logic);
end entity clock_generator; end entity clock_generator;


architecture rtl of clock_generator is architecture rtl of clock_generator is
signal clkfb : std_ulogic;


signal clkfb : std_ulogic; type pll_settings_t is record
clkin_period : real range 0.000 to 52.631;
clkfbout_mult : integer range 2 to 64;
clkout_divide : integer range 1 to 128;
divclk_divide : integer range 1 to 56;
force_rst : std_ulogic;
end record;


type pll_settings_t is record function gen_pll_settings (
clkin_period : real range 0.000 to 52.631; constant input_hz : positive;
clkfbout_mult : integer range 2 to 64; constant output_hz : positive)
clkout_divide : integer range 1 to 128; return pll_settings_t is
divclk_divide : integer range 1 to 56;
end record;


function gen_pll_settings ( constant bad_settings : pll_settings_t :=
constant freq_hz : positive) (clkin_period => 0.0,
return pll_settings_t is clkfbout_mult => 2,
begin clkout_divide => 1,
if freq_hz = 100000000 then divclk_divide => 1,
return (clkin_period => 10.0, force_rst => '1');
clkfbout_mult => 16, begin
clkout_divide => 32, case input_hz is
divclk_divide => 1); when 100000000 =>
else case output_hz is
report "Unsupported input frequency" severity failure; when 100000000 =>
-- return (clkin_period => 0.0, return (clkin_period => 10.0,
-- clkfbout_mult => 0, clkfbout_mult => 16,
-- clkout_divide => 0, clkout_divide => 16,
-- divclk_divide => 0); divclk_divide => 1,
end if; force_rst => '0');
end function gen_pll_settings; when 50000000 =>
return (clkin_period => 10.0,
clkfbout_mult => 16,
clkout_divide => 32,
divclk_divide => 1,
force_rst => '0');
when others =>
report "Unsupported output frequency" severity failure;
return bad_settings;
end case;
when others =>
report "Unsupported input frequency" severity failure;
return bad_settings;
end case;
end function gen_pll_settings;


constant pll_settings : pll_settings_t := gen_pll_settings(clk_period_hz); constant pll_settings : pll_settings_t := gen_pll_settings(clk_input_hz,
clk_output_hz);
begin begin


pll : PLLE2_BASE pll : PLLE2_BASE
generic map ( generic map (
BANDWIDTH => "OPTIMIZED", BANDWIDTH => "OPTIMIZED",
CLKFBOUT_MULT => pll_settings.clkfbout_mult, CLKFBOUT_MULT => pll_settings.clkfbout_mult,
CLKIN1_PERIOD => pll_settings.clkin_period, CLKIN1_PERIOD => pll_settings.clkin_period,
CLKOUT0_DIVIDE => pll_settings.clkout_divide, CLKOUT0_DIVIDE => pll_settings.clkout_divide,
DIVCLK_DIVIDE => pll_settings.divclk_divide, DIVCLK_DIVIDE => pll_settings.divclk_divide,
STARTUP_WAIT => "FALSE") STARTUP_WAIT => "FALSE")
port map ( port map (
CLKOUT0 => pll_clk_out, CLKOUT0 => pll_clk_out,
CLKOUT1 => open, CLKOUT1 => open,
CLKOUT2 => open, CLKOUT2 => open,
CLKOUT3 => open, CLKOUT3 => open,
CLKOUT4 => open, CLKOUT4 => open,
CLKOUT5 => open, CLKOUT5 => open,
CLKFBOUT => clkfb, CLKFBOUT => clkfb,
LOCKED => pll_locked_out, LOCKED => pll_locked_out,
CLKIN1 => ext_clk, CLKIN1 => ext_clk,
PWRDWN => '0', PWRDWN => '0',
RST => pll_rst_in, RST => pll_rst_in or pll_settings.force_rst,
CLKFBIN => clkfb); CLKFBIN => clkfb);


end architecture rtl; end architecture rtl;

8
fpga/toplevel.vhdl
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@ -5,7 +5,9 @@ entity toplevel is
generic ( generic (
MEMORY_SIZE : positive := 524288; MEMORY_SIZE : positive := 524288;
RAM_INIT_FILE : string := "firmware.hex"; RAM_INIT_FILE : string := "firmware.hex";
RESET_LOW : boolean := true RESET_LOW : boolean := true;
CLK_INPUT : positive := 100000000;
CLK_FREQUENCY : positive := 100000000
); );
port( port(
ext_clk : in std_ulogic; ext_clk : in std_ulogic;
@ -43,6 +45,10 @@ begin
); );


clkgen: entity work.clock_generator clkgen: entity work.clock_generator
generic map(
CLK_INPUT_HZ => CLK_INPUT,
CLK_OUTPUT_HZ => CLK_FREQUENCY
)
port map( port map(
ext_clk => ext_clk, ext_clk => ext_clk,
pll_rst_in => pll_rst, pll_rst_in => pll_rst,

42
microwatt.core
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@ -81,7 +81,11 @@ targets:
nexys_a7: nexys_a7:
default_tool: vivado default_tool: vivado
filesets: [core, nexys_a7, soc, fpga, debug_xilinx] filesets: [core, nexys_a7, soc, fpga, debug_xilinx]
parameters : [memory_size, ram_init_file] parameters :
- memory_size
- ram_init_file
- clk_input
- clk_frequency
tools: tools:
vivado: {part : xc7a100tcsg324-1} vivado: {part : xc7a100tcsg324-1}
toplevel : toplevel toplevel : toplevel
@ -89,7 +93,11 @@ targets:
nexys_video: nexys_video:
default_tool: vivado default_tool: vivado
filesets: [core, nexys_video, soc, fpga, debug_xilinx] filesets: [core, nexys_video, soc, fpga, debug_xilinx]
parameters : [memory_size, ram_init_file] parameters :
- memory_size
- ram_init_file
- clk_input
- clk_frequency
tools: tools:
vivado: {part : xc7a200tsbg484-1} vivado: {part : xc7a200tsbg484-1}
toplevel : toplevel toplevel : toplevel
@ -97,7 +105,11 @@ targets:
arty_a7-35: arty_a7-35:
default_tool: vivado default_tool: vivado
filesets: [core, arty_a7, soc, fpga, debug_xilinx] filesets: [core, arty_a7, soc, fpga, debug_xilinx]
parameters : [memory_size, ram_init_file] parameters :
- memory_size
- ram_init_file
- clk_input
- clk_frequency
tools: tools:
vivado: {part : xc7a35ticsg324-1L} vivado: {part : xc7a35ticsg324-1L}
toplevel : toplevel toplevel : toplevel
@ -105,7 +117,11 @@ targets:
arty_a7-100: arty_a7-100:
default_tool: vivado default_tool: vivado
filesets: [core, arty_a7, soc, fpga, debug_xilinx] filesets: [core, arty_a7, soc, fpga, debug_xilinx]
parameters : [memory_size, ram_init_file] parameters :
- memory_size
- ram_init_file
- clk_input
- clk_frequency
tools: tools:
vivado: {part : xc7a100ticsg324-1L} vivado: {part : xc7a100ticsg324-1L}
toplevel : toplevel toplevel : toplevel
@ -113,7 +129,11 @@ targets:
cmod_a7-35: cmod_a7-35:
default_tool: vivado default_tool: vivado
filesets: [core, cmod_a7-35, soc, fpga, debug_xilinx] filesets: [core, cmod_a7-35, soc, fpga, debug_xilinx]
parameters : [memory_size, ram_init_file, reset_low=false] parameters :
- memory_size
- ram_init_file
- reset_low=false
- clk_input=12000000
tools: tools:
vivado: {part : xc7a35tcpg236-1} vivado: {part : xc7a35tcpg236-1}
toplevel : toplevel toplevel : toplevel
@ -139,3 +159,15 @@ parameters:
datatype : bool datatype : bool
description : External reset button polarity description : External reset button polarity
paramtype : generic paramtype : generic

clk_input:
datatype : int
description : Clock input frequency in HZ (for top-generic based boards)
paramtype : generic
default : 100000000

clk_frequency:
datatype : int
description : Generated system clock frequency in HZ (for top-generic based boards)
paramtype : generic
default : 50000000

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