This adds an optional 16 bit x 16 bit signed multiplier and uses it
for multiply instructions that return the low 64 bits of the product
(mull[dw][o] and mulli, but not maddld) when the operands are both in
the range -2^15 .. 2^15 - 1. The "short" 16-bit multiplier produces
its result combinatorially, so a multiply that uses it executes in one
cycle. This improves the coremark result by about 4%, since coremark
does quite a lot of multiplies and they almost all have operands that
fit into 16 bits.
The presence of the short multiplier is controlled by a generic at the
execute1, SOC, core and top levels. For now, it defaults to off for
all platforms, and can be enabled using the --has_short_mult flag to
fusesoc.
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
The verilator build fails with warnings and errors, because NGPIO
is 0 and we do things like:
gpio_out : out std_ulogic_vector(NGPIO - 1 downto 0);
Set NGPIO to something reasonable (eg 32) and add HAS_GPIO to avoid
building the macro entirely if it isn't in use.
Signed-off-by: Anton Blanchard <anton@linux.ibm.com>
Experimenting with using ghdl to do VHDL to Verilog conversion (instead
of ghdl+yosys), verilator complains that a signal is a SystemVerilog
keyword:
%Error: microwatt.v:15013:18: Unexpected 'do': 'do' is a SystemVerilog keyword misused as an identifier.
... Suggest modify the Verilog-2001 code to avoid SV keywords, or use `begin_keywords or --language.
We could probably make this go away by disabling SystemVerilog, but
it's easy to rename the signal in question. Rename di at the same
time.
Signed-off-by: Anton Blanchard <anton@linux.ibm.com>
The icache RAM is currently LUT ram not block ram. This massively
bloats the icache size. We think this is due to yosys not inferencing
the RAM correctly but that's yet to be confirmed.
Work around this for now by reducing the default size of the icache
RAM for the ECP5 builds.
On the ECP5 85K builts, this gets us from 95% down to 76% and helps
our CI to pass.
Signed-off-by: Michael Neuling <mikey@neuling.org>
This adds litesdcard.v generated from the litex/litesdcard project,
along with logic in top-arty.vhdl to connect it into the system.
There is now a DMA wishbone coming in to soc.vhdl which is narrower
than the other wishbone masters (it has 32-bit data rather than
64-bit) so there is a widening/narrowing adapter between it and the
main wishbone master arbiter.
Also, litesdcard generates a non-pipelined wishbone for its DMA
connection, which needs to be converted to a pipelined wishbone. We
have a latch on both the incoming and outgoing sides of the wishbone
in order to help make timing (at the cost of two extra cycles of
latency).
litesdcard generates an interrupt signal which is wired up to input 3
of the ICS (IRQ 19).
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
This adds a GPIO controller which provides 32 bits of I/O. The
registers are modelled on the set used by the gpio-ftgpio010.c driver
in the Linux kernel. Currently there is no interrupt capability
implemented, though an interrupt line from the GPIO subsystem to the
XICS has been connected.
For the Arty A7 board, GPIO lines 0 to 13 are connected to the pins
labelled IO0 to IO13 on the "shield" connector, GPIO lines 14 to 29
connect to IO26 to IO41, GPIO line 30 connects to the pin labelled A
(aka IO42), and GPIO line 31 is connected to LED 7.
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
This implements a cache in fetch1, where each entry stores the address
of a simple branch instruction (b or bc) and the target of the branch.
When fetching sequentially, if the address being fetched matches the
cache entry, then fetching will be redirected to the branch target.
The cache has 1024 entries and is direct-mapped, i.e. indexed by bits
11..2 of the NIA.
The bus from execute1 now carries information about taken and
not-taken simple branches, which fetch1 uses to update the cache.
The cache entry is updated for both taken and not-taken branches, with
the valid bit being set if the branch was taken and cleared if the
branch was not taken.
If fetching is redirected to the branch target then that goes down the
pipe as a predicted-taken branch, and decode1 does not do any static
branch prediction. If fetching is not redirected, then the next
instruction goes down the pipe as normal and decode1 does its static
branch prediction.
In order to make timing, the lookup of the cache is pipelined, so on
each cycle the cache entry for the current NIA + 8 is read. This
means that after a redirect (from decode1 or execute1), only the third
and subsequent sequentially-fetched instructions will be able to be
predicted.
This improves the coremark value on the Arty A7-100 from about 180 to
about 190 (more than 5%).
The BTC is optional. Builds for the Artix 7 35-T part have it off by
default because the extra ~1420 LUTs it takes mean that the design
doesn't fit on the Arty A7-35 board.
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
This adds, as comments, lines which would if uncommented define
properties which associate the pins of the headers on the Arty A7
board with FPGA pins. It also adds properties for LEDs 1--3, also
commented out for now.
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
This extends the register file so it can hold FPR values, and
implements the FP loads and stores that do not require conversion
between single and double precision.
We now have the FP, FE0 and FE1 bits in MSR. FP loads and stores
cause a FP unavailable interrupt if MSR[FP] = 0.
The FPU facilities are optional and their presence is controlled by
the HAS_FPU generic passed down from the top-level board file. It
defaults to true for all except the A7-35 boards.
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
This is a NiteFury based PCIe M2 form-factor board originally
used for mining. It contains a speed grade 2 Artix 7 200T,
1GB of DDR3 and 32MB of flash.
The serial port is routed to pin 2 (RX) and 3 (TX) of the P2
connector (pin 1 is GND).
Note: Only 16MB of flash is currently usable until code is added
to configure the flash controller to use 4-bytes address commands
on that part.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
This adds a true random number generator for the Xilinx FPGAs which
uses a set of chaotic ring oscillators to generate random bits and
then passes them through a Linear Hybrid Cellular Automaton (LHCA) to
remove bias, as described in "High Speed True Random Number Generators
in Xilinx FPGAs" by Catalin Baetoniu of Xilinx Inc., in:
https://pdfs.semanticscholar.org/83ac/9e9c1bb3dad5180654984604c8d5d8137412.pdf
This requires adding a .xdc file to tell vivado that the combinatorial
loops that form the ring oscillators are intentional. The same
code should work on other FPGAs as well if their tools can be told to
accept the combinatorial loops.
For simulation, the random.vhdl module gets compiled in, which uses
the pseudorand() function to generate random numbers.
Synthesis using yosys uses nonrandom.vhdl, which always signals an
error, causing darn to return 0xffff_ffff_ffff_ffff.
This adds an implementation of the darn instruction. Darn can return
either raw or conditioned random numbers. On Xilinx FPGAs, reading a
raw random number gives the output of the ring oscillators, and
reading a conditioned random number gives the output of the LHCA.
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
Make the DRAM data lines and user port width configurable, also
don't hard wire dependency on the wishbone data width.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
This fixes up a few issues with parameters:
Only arty has "has_uart1" since we haven't added plumbing for a second UART
anywhere else. Also "uart_is_16550" was mixing on one of the nexys_video
targets, and nexys_video toplevel was missing LOG_LENGTH.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Means we can synthesize at 40Mhz (where we currently make timing) and
our UART still works at 115200 baud.
Tested working hello world unmodified with ECP5 eval board. Orange
Crab is updated but is untested.
Signed-off-by: Michael Neuling <mikey@neuling.org>
This imports via fusesoc a 16550 compatible (ie "standard") UART,
and wires it up optionally in the SoC instead of the potato one.
This also adds support for a second UART (which is always a
16550) to Arty, wired to JC "bottom" port.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
No cells matched 'get_cells -hierarchical -filter {NAME =~*/spi_rxtx/dat_i_l*}'. [build/microwatt_0/src/microwatt_0/fpga/arty_a7.xdc:42]
The signal is in it's own process so the net name ends up being
spi_rxtx/input_delay_1.dat_i_l_reg.
After this change the log shows:
Applied set_property IOB = TRUE for soc0/\spiflash_gen.spiflash /spi_rxtx/\input_delay_1.dat_i_l_reg . (constraint file fpga/arty_a7.xdc, line 42).
Applied set_property IOB = TRUE for soc0/\spiflash_gen.spiflash /spi_rxtx/\input_delay_1.dat_i_l_reg . (constraint file fpga/arty_a7.xdc, line 42).
Applied set_property IOB = TRUE for soc0/\spiflash_gen.spiflash /spi_rxtx/\input_delay_1.dat_i_l_reg . (constraint file fpga/arty_a7.xdc, line 42).
Applied set_property IOB = TRUE for soc0/\spiflash_gen.spiflash /spi_rxtx/\input_delay_1.dat_i_l_reg . (constraint file fpga/arty_a7.xdc, line 42).
Signed-off-by: Joel Stanley <joel@jms.id.au>
Make the core go faster
Several major improvements in here:
- Simple branch predictor
- Reduced latency for mispredicted branches and interrupts by removing fetch2 stage
- Cache improvements
o Request critical dword first on refill
o Handle hits while refilling, including on line being refilled
o Sizes doubled for both D and I
- Loadstore improvements: can now do one load or store every two cycles in most cases
- Optimized 2-cycle multiplier for Xilinx 7-series parts using DSP slices
- Timing improvements, including:
o Stash buffer in decode1
o Reduced width of execute1 result mux
o Improved SPR decode in decode1
o Some non-critical operation take a cycle longer so we can break some long combinatorial chains
- Core logging: logs 256 bits of info every cycle into a ring buffer, to help with debugging and performance analysis
This increases the LUT usage for the "synth" + A35 target from 9182 to 10297 = 12%.
This plumbs the LOG_LENGTH parameter (which controls how many entries
the core log RAM has) up to the top level so that it can be set on
the fusesoc command line and have different default values on
different FPGAs.
It now defaults to 512 entries generally and on the Artix-7 35 parts,
and 2048 on the larger Artix-7 FPGAs. It can be set to 0 if desired.
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
This makes the control bus currently going out of "soc" towards
litedram more generic for external IO devices added by the
top-level rather than inside the SoC proper.
This is mostly renaming of signals and a small change on how the
address decoder operates, using a separate "cascaded" decode for
the external IOs.
We make the region 0xc8nn_nnnn be the "external IO" region for
now.
This will make it easier / cleaner to add more external devices.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Currently, when not using litedram, the top level still has to hook
up "dummy" wishbones to the main dram and control dram busses coming
out of the SoC and provide ack signals.
Instead, make the SoC generate the acks internally when not using
litedram and use defaults to make the wiring entirely optional.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
That way the top-level's don't need to assign them
Also remove generics that are set to the default anyways
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
They hurt timing forcing signals to come from the master and back
again in one cycle. Stall isn't sampled by the master unless there
is an active cycle so masking it with cyc is pointless. Masking acks
is somewhat pointless too as we don't handle early dropping of cyc
in any of our slaves properly anyways.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
This adds an SPI flash controller which supports direct
memory-mapped access to the flash along with a manual
mode to send commands.
The direct mode can be set via generic to default to single
wire or quad mode. The controller supports normal, dual and quad
accesses with configurable commands, clock divider, dummy clocks
etc...
The SPI clock can be an even divider of sys_clk starting at 2
(so max 50Mhz with our typical Arty designs).
A flash offset is carried via generics to syscon to tell SW about
which portion of the flash is reserved for the FPGA bitfile. There
is currently no plumbing to make the CPU reset past that address (TBD).
Note: Operating at 50Mhz has proven unreliable without adding some
delay to the sampling of the input data. I'm working in improving
this, in the meantime, I'm leaving the default set at 25 Mhz.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
The DRAM related pins have some small changes in LiteX, so resync
and add the false path information as well.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
We still had some wires bringing an extra serial port out of
litedram for the built-in riscv processor. This is all gone now
so take them out.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
This adds an option to disable the main BRAM and instead copy a
payload stashed along with the init code in the secondary BRAM
into DRAM and boot from there
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
This changes the SoC interconnect such that the main 64-bit wishbone out
of the processor is first split between only 3 slaves (BRAM, DRAM and a
general "IO" bus) instead of all the slaves in the SoC.
The IO bus leg is then latched and down-converted to 32 bits data width,
before going through a second address decoder for the various IO devices.
This significantly reduces routing and timing pressure on the main bus,
allowing to get rid of frequent timing violations when synthetizing on
small'ish FPGAs such as the Artix-7 35T found on the original Arty board.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
When using litedram, request a much longer PLL reset. This seems to
help get rid of all the grabled output after config.
Also use the clean system_rst out of litedram as our source of reset
for the rest of the SoC (it is synchronized with system_clk and takes
pll_locked into account already)
In some cases we need to keep the reset held for much longer,
so use counters rather than shift registers.
Additionally, some signals such as ext_rst and pll_locked
or signals going from the ext_clk domain to the pll_clk
domain need to be treated as async, and testing them without
synchronizers is asking for trouble.
Finally, make the external reset also reset the PLL.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Things have changed a bit in upstream LiteX. LiteDRAM now exposes a
wishbone for the CSRs for example.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Paul Mackerras
Anton Blanchard
Michael Neuling