At present, the loop in the irq_gen process generates a chain of
comparators and other logic to work out the source number and priority
of the most-favoured (lowest priority number) pending interrupt.
This replaces that chain with (1) logic to generate an array of bits,
one per priority, indicating whether any interrupt is pending at that
priority, (2) a priority encoder to select the most favoured priority
with an interrupt pending, (3) logic to generate an array of bits, one
per source, indicating whether an interrupt is pending at the priority
calculated in step 2, and (4) a priority encoder to work out the
lowest numbered source that has an interrupt pending at the selected
priority. This reduces LUT utilization.
The priority encoder function implemented here uses the optimized
count-leading-zeroes logic from helpers.vhdl.
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
This implements an alternative count-leading-zeroes algorithm which
uses less LUTs to generate the higher-order bits (2..5) of the
result.
By doing (v | -v) rather than (v & -v), we get a value which has ones
from the MSB down to the rightmost 1 bit in v and then zeroes down to
the LSB. This means that we can generate the MSB of the result (the
index of the rightmost 1 bit in v) just by looking at bits 63 and 31
of (v | -v), assuming that v is 64 bits. Bit 4 of the result requires
looking at bits 63, 47, 31 and 15. In contrast, each bit of the
result using (v & -v), which has a single 1, requires ORing together
32 bits.
It turns out that the minimum LUT usage comes from using (v & -v) to
generate bits 0 and 1 of the result, and using (v | -v) to generate
bits 2 to 5. This saves almost 60 6-input LUTs on the Artix-7.
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
This generates a series of io_cycle_* signals which are clean latches
and which become the 'cyc' signals of the wishbone buses going to
various peripherals (syscon, uarts, XICS, GPIO, etc.). Effectively
this is done by moving the address decoding into the slave_io_latch
process. The slave_io_type, which drives the multiplexer which
selects which wishbone to look for a response on, is reduced to just 8
values in the expectation that an 8-way multiplexer will use less
logic than one with more than 8 inputs.
With this timing is considerably better on the A7-100T.
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
"-b ecp5" will select ECP5 interface that talks to a JTAGG
primitive.
For example with a FT232H JTAG board:
./mw_debug -t 'ft2232 vid=0x0403 pid=0x6014' -s 30000000 -b ecp5 mr ff003888 6
Connected to libftdi driver.
Found device ID: 0x41113043
00000000ff003888: 6d6f636c65570a0a ..Welcom
00000000ff003890: 63694d206f742065 e to Mic
00000000ff003898: 2120747461776f72 rowatt !
00000000ff0038a0: 0000000000000a0a ........
00000000ff0038a8: 67697320636f5320 Soc sig
00000000ff0038b0: 203a65727574616e nature:
Core: running
NIA: c0000000000187f8
MSR: 9000000000001033
Signed-off-by: Matt Johnston <matt@codeconstruct.com.au>
This uses the JTAGG primitive which is similar to BSCANE2.
The LUT4 delay approach came from Florian and Greg in
https://github.com/enjoy-digital/litex/pull/1087
Has been tested on an OrangeCrab with 48MHz sysclk
FT232H up to 30MHz (though libusb/urjtag is by far the bottleneck vs
the JTAG clock)
Signed-off-by: Matt Johnston <matt@codeconstruct.com.au>
liburjtag isn't in Debian, so usually we're pointing at a urjtag
build directory when building mw_debug
Signed-off-by: Matt Johnston <matt@codeconstruct.com.au>
This removes logic that I added some time ago with the thought that it
would enable us to do prefetching in the icache. This logic detects
when the fetch address is an odd multiple of 4 and the next address in
sequence from the previous cycle. In that case the instruction we
want is in the output register of the icache RAM already so there is
no need to do another read or any icache tag or TLB lookup.
However, this logic adds complexity, and removing it improves timing,
so this removes it.
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
This moves the calculation of the result for popcnt* into the
countbits unit, renamed from countzero, so that we can take two cycles
to get the result. The motivation for this is that the popcnt*
calculation was showing up as a critical path.
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
Orangecrab missed out on:
Make wishbone addresses be in units of doublewords or words
Author: Paul Mackerras <paulus@ozlabs.org>
Date: Wed Sep 15 18:18:09 2021 +1000
Signed-off-by: Matt Johnston <matt@codeconstruct.com.au>
Modifies litescard generate script to take a clock speed.
Regenerated verilog with latest litesdcard
e52c731 ("Bump year.")
Signed-off-by: Matt Johnston <matt@codeconstruct.com.au>
Reduce litedram NUM_LINES 64->8
This allows us to meet timing. Can probably
be improved in future with better BRAM usage.
Signed-off-by: Matt Johnston <matt@codeconstruct.com.au>
top-orangecrab0.2 is a copy of top-arty with various changes.
USRMCLK is added for the SPI clock
ethernet is removed
Signed-off-by: Matt Johnston <matt@codeconstruct.com.au>
Parameters are based on
https://github.com/gregdavill/OrangeCrab-test-sw/blob/main/hw/OrangeCrab-bitstream.py
and litex-boards orangecrab.py
rtt_nom and cmd_delay are overridden for OrangeCrab, we do the same here.
Generated with litedram and litex
62abf9c ("litedram_gen: Add block_until_ready port parameter to control blocking behaviour.")
add2746a ("tools/litex_cli: Rename wb to bus.")
Signed-off-by: Matt Johnston <matt@codeconstruct.com.au>
Recent litedram gets stuck at memtest unless block_until_ready=False.
(discussion in https://github.com/enjoy-digital/litedram/pull/292)
This change regenerates with latest litedram and litex
62abf9c ("litedram_gen: Add block_until_ready port parameter to control blocking behaviour.")
add2746a ("tools/litex_cli: Rename wb to bus.")
Signed-off-by: Matt Johnston <matt@codeconstruct.com.au>
Yosys changed command line behaviour following the v0.12 release. Work
around this by using read_verilog, which maintains the old behaviour.
This should work fine for current yosys and be compatible with
future releases.
See https://github.com/YosysHQ/yosys/issues/3109
Signed-off-by: Joel Stanley <joel@jms.id.au>
At present, code (such as simple_random) which produces serial port
output during the first few milliseconds of operation produces garbled
output. The reason is that the clock has not yet stabilized and is
running slow, resulting in the bit time of the serial characters being
too long.
The ECP5 data sheet says that the phase detector should be operated
between 10 and 400 MHz. The current code operates it at 2MHz.
Consequently, the PLL lock indication doesn't work, i.e. it is always
zero. The current code works around that by inverting it, i.e. taking
the "not locked" indication to mean "locked".
Instead, we now run it at 12MHz, chosen because the common external
clock inputs on ECP5 boards are 12MHz and 48MHz. Normally this would
mean that the available system clock frequencies would be multiples of
12MHz, but this is a little inconvenient as we use 40MHz on the Orange
Crab v0.21 boards. Instead, by using the secondary clock output for
feedback, we can have any divisor of the PLL frequency as the system
clock frequency.
The ECP5 data sheet says the PLL oscillator can run at 400 to 800
MHz. Here we choose 480MHz since that allows us to generate 40MHz and
48MHz easily and is a multiple of 12MHz.
With this, the lock signal works correctly, and the inversion can be
removed.
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
The existing orange crab target is for an older board with a
LFE5UM5G-85F device. Newer orange crab boards (v0.21) have a
LFE5U-85F device in the -8 speed grade, so make a new target for them
called ORANGE-CRAB-0.21.
Also add flags to ecppack to indicate that the bitstream should be
compressed and can be loaded at 38.8MHz.
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
These convert addresses to/from wishbone addresses, and use them
in parts of the caches, in order to make the code a bit more readable.
Along the way, rename some functions in the caches to make it a bit
clearer what they operate on and fix a bug in the icache STOP_RELOAD state where
the wb address wasn't properly converted.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
This moves REAL_ADDR_BITS out of the caches and defines a real_addr_t
type for a real address, along with a addr_to_real() conversion helper.
It makes the vhdl a bit more readable
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
We have a bug where an store near a dcbz can cause the dcbz to only zero
8 bytes. Add a test case for this.
Signed-off-by: Anton Blanchard <anton@linux.ibm.com>
Note: There are a few patches to upstream to fix an upstream breakage
of litedram standalone generator, and fix some issues with liteeth
in the way it's used on Wukong. All these have pending pull requests.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
For now only the V2 of the board (slightly different pinout)
and only the A100T variant. I also haven't added GPIOs or anything
else on the PMODs really.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Michael Neuling
Paul Mackerras
Anton Blanchard