Commit Graph

1213 Commits (caravel-mpw7-20220822)
 

Author SHA1 Message Date
Paul Mackerras 6427cab46f loadstore1/dcache: Send store data one cycle later
This makes timing easier and also means that store floating-point
single precision instructions no longer need to take an extra cycle.

Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
Paul Mackerras 4b2c23703c core: Implement quadword loads and stores
This implements the lq, stq, lqarx and stqcx. instructions.

These instructions all access two consecutive GPRs; for example the
"lq %r6,0(%r3)" instruction will load the doubleword at the address
in R3 into R7 and the doubleword at address R3 + 8 into R6.  To cope
with having two GPR sources or destinations, the instruction gets
repeated at the decode2 stage, that is, for each lq/stq/lqarx/stqcx.
coming in from decode1, two instructions get sent out to execute1.

For these instructions, the RS or RT register gets modified on one
of the iterations by setting the LSB of the register number.  In LE
mode, the first iteration uses RS|1 or RT|1 and the second iteration
uses RS or RT.  In BE mode, this is done the other way around.  In
order for decode2 to know what endianness is currently in use, we
pass the big_endian flag down from icache through decode1 to decode2.
This is always in sync with what execute1 is using because only rfid
or an interrupt can change MSR[LE], and those operations all cause
a flush and redirect.

There is now an extra column in the decode tables in decode1 to
indicate whether the instruction needs to be repeated.  Decode1 also
enforces the rule that lq with RT = RT and lqarx with RA = RT or
RB = RT are illegal.

Decode2 now passes a 'repeat' flag and a 'second' flag to execute1,
and execute1 passes them on to loadstore1.  The 'repeat' flag is set
for both iterations of a repeated instruction, and 'second' is set
on the second iteration.  Execute1 does not take asynchronous or
trace interrupts on the second iteration of a repeated instruction.

Loadstore1 uses 'next_addr' for the second iteration of a repeated
load/store so that we access the second doubleword of the memory
operand.  Thus loadstore1 accesses the doublewords in increasing
memory order.  For 16-byte loads this means that the first iteration
writes GPR RT|1.  It is possible that RA = RT|1 (this is a legal
but non-preferred form), meaning that if the memory operand was
misaligned, the first iteration would overwrite RA but then the
second iteration might take a page fault, leading to corrupted state.
To avoid that possibility, 16-byte loads in LE mode take an
alignment interrupt if the operand is not 16-byte aligned.  (This
is the case anyway for lqarx, and we enforce it for lq as well.)

Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
Paul Mackerras d1f35705c0 loadstore1: Improve timing of data path from cache RAM to writeback
Work out select inputs for writeback mux a cycle earlier.

Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
Paul Mackerras 784d409999 dcache: Add more commentary, no code change
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
Paul Mackerras 54f89afab7 loadstore1: Decide on load formatting controls a cycle earlier
This helps timing.

Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
Paul Mackerras 55f7d99376 decode1: Fix decoding of recommended NOP instruction
We were decoding nop with the wrong major opcode.  Fix it.

Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
Paul Mackerras 3361c460b8 core_debug: Stop logging 256 cycles after trigger
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
Paul Mackerras 470f1b2140 core_debug: Add an address trigger to stop logging at a given address
This compares the address being fetched with the contents of a
register that can be set via DMI, and if they match, stops the
logging.  Since this works on the address being fetched rather than
executed, it is subject to false positives.

Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
Paul Mackerras 5535257c71 FPU: Don't use mask generator for rounding
Instead of using the mask generator in the rounding process, this uses
simpler logic to add in a 1 at the appropriate position (bit 2 or bit
31, depending on precision) and mask off the low-order bits.  Since
there are only two positions at which the masking and incrementing
need to be done, we don't need the full generality of the mask
generator.  This reduces the amount of logic and improves timing.

Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
Paul Mackerras 45c5236700 FPU: Relax timing around multiplier output
At present there is a state transition in the handling of the fmadd
instructions where the next state depends on the sign bit of the
multiplier result.  This creates a critical path which doesn't make
timing on the A7-100.  To fix this, we make the state transition
independent of the sign of the multiplier result, which improves
timing, but means we take one more cycle to do a fmadd-family
instruction in some cases.

Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
Paul Mackerras f14e731ec6 mw_debug: Display terminated status when stopping
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
Paul Mackerras 6baf3b519f mw_debug: Extend to handle FPRs
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
Paul Mackerras 2be2440734 Arty A7: Document pin connections for on-board headers
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>
Paul Mackerras d5cf4acfdb execute1: Update comments about XER forwarding
This deletes some commentary that is now out of date and replaces it
with a simple statement about the XER common bits being forwarded from
the output of execute1 to the input.

The comment being deleted talked about a hazard if an instruction that
modifies XER[SO] is immediately followed by a store conditional.  That
is no longer a problem because the operands for loadstore1 are sent
from execute1 (and therefore have the forwarded value) rather than
decode2.  This was in fact fixed in 5422007f83 ("Plumb loadstore1
input from execute1 not decode2", 2020-01-14).

Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
Paul Mackerras 5f8279a14a
Merge pull request from antonblanchard/reset-pid
Initialize PID register
Paul Mackerras 45b7312e89
Merge pull request from antonblanchard/reset-tb-decr
Reset TB and DECR
Paul Mackerras 00446a9169
Merge pull request from antonblanchard/dmi-reset
Reset JTAG/DMI
Anton Blanchard 3f1e2b3a4f
Merge pull request from antonblanchard/another-spi-rxtx-reset-issu
Fix another reset issue in spi_rxtx
Anton Blanchard 75be7803b2
Merge pull request from antonblanchard/reset-spi-txrx
Reset cmd_ready_o in spi_txrx
Anton Blanchard 740f013284 Initialize PID register
If the PID register is read before it is written we'll consume
X state data.

Signed-off-by: Anton Blanchard <anton@linux.ibm.com>
Anton Blanchard a0eb4eec17 Fix another reset issue in spi_rxtx
counter was X state after reset, initialize it.

Signed-off-by: Anton Blanchard <anton@linux.ibm.com>
Anton Blanchard bf9a446e3f Reset cmd_ready_o in spi_txrx
Initialize bit_count so that cmd_ready_o isn't X state immediately
after reset.

Signed-off-by: Anton Blanchard <anton@linux.ibm.com>
Anton Blanchard e1bac4d6e7 Reset TB and DECR
We don't care what the values of TB and DECR are after reset, but we
don't want the X state to propagate to other parts of the chip.

Signed-off-by: Anton Blanchard <anton@linux.ibm.com>
Anton Blanchard 39c826aa46
Merge pull request from antonblanchard/wishbone_layout
Make wishbone_master_out and wb_io_master_out match
Anton Blanchard ebe696affc
Merge pull request from paulusmack/misc
soc: Drive uart1_irq to 0 when we don't have UART1
Anton Blanchard c6dfc19d89 Make wishbone_master_out and wb_io_master_out match
This makes it easier to parse the records in verilog because they
are getting flattened into an array of bits by ghdl/yosys.

Signed-off-by: Anton Blanchard <anton@linux.ibm.com>
Paul Mackerras e41cb01bca fetch1: Fix debug stop
The ability to stop the core using the debug interface has been broken
since commit bb4332b7e6b5 ("Remove fetch2 pipeline stage"), which
removed a statement that cleared the valid bit on instructions when
their stop_mark was 1.

Fix this by clearing r.req coming out of fetch1 when r.stop_mark = 1.
This has the effect of making i_out.valid be 0 from the icache.  We
also fix a bug in icache.vhdl where it was not honouring i_in.req when
use_previous = 1.

It turns out that the logic in fetch1.vhdl to handle stopping and
restarting was not correct, with the effect that stopping the core
would leave NIA pointing to the last instruction executed, not the
next instruction to be executed.  In fact the state machine is
unnecessary and the whole thing can be simplified enormously - we
need to increment NIA whenever stop_in = 0 in the previous cycle.

Fixes: bb4332b7e6b5 ("Remove fetch2 pipeline stage")
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
Paul Mackerras 97586e7e99 soc: Drive uart1_irq to 0 when we don't have UART1
The tools complain about uart1_irq not being driven and not having a
default when HAS_UART1 is false.  This sets it to 0 in that case.

Fixes: 7575b1e0c2 ("uart: Import and hook up opencore 16550 compatible UART")
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
Anton Blanchard 5eb351b4be Reset JTAG/DMI
request is never initialized and we leak X state control signals to other
parts of the core (eg dmi_wr). Add a reset.

Signed-off-by: Anton Blanchard <anton@linux.ibm.com>
Michael Neuling d96ee21c39
Merge pull request from antonblanchard/flash-reset
Fix a few reset issues in flash controller
Paul Mackerras f4831507b3
Merge pull request from antonblanchard/nofpu-fix
Fully initialize FPU buses when FPU is disabled
Anton Blanchard c870040a20 Fix an issue in flash controller when BOOT_CLOCKS is false
If BOOT_CLOCKS is false we currently get stuck in the flash
state machine. This patch from Ben fixes it.

Also fix an x state issue I see in icarus verilog where we need
to reset auto_state.

Signed-off-by: Anton Blanchard <anton@linux.ibm.com>
Anton Blanchard 659be2780f Fully initialize FPU buses when FPU is disabled
Some of the bits in the FPU buses end up as z state. Yosys
flags them, so we may as well clean it up.

Signed-off-by: Anton Blanchard <anton@linux.ibm.com>
Anton Blanchard 7c8bc85e44 Fix a few reset issues in flash controller
Our flash controller fails when simulating with iverilog. Looking
closer, both wb_stash and auto_last_addr are X state, and things
fall apart after they get used.

Initialise them both fixes the iverilog issue.

Signed-off-by: Anton Blanchard <anton@linux.ibm.com>
Anton Blanchard 081dc64d39
Merge pull request from antonblanchard/log-length
Add LOG_LENGTH to top-generic.vhdl
Anton Blanchard 86bdfe6fd4
Merge pull request from antonblanchard/fix-verilator
Add verilator FPGA target
Anton Blanchard 80cf489e96 Add LOG_LENGTH to top-generic.vhdl
The other top level files allow LOG_LENGTH to be configured.

Signed-off-by: Anton Blanchard <anton@linux.ibm.com>
Anton Blanchard df8e1ca2a7 Add verilator FPGA target
Our Makefiles need some work, but for now create an FPGA target:

make FPGA_TARGET=verilator microwatt-verilator

ghdl and yosys can use containers using PODMAN=1 or DOCKER=1
options.

Signed-off-by: Anton Blanchard <anton@linux.ibm.com>
Anton Blanchard 62d5b16c66
Merge pull request from antonblanchard/fix-verilator
Fix verilator build
Anton Blanchard 4bc5169f78 Fix verilator build
yosys and verilator did not like us passing in the verilog and
exporting it again. Pass the source directly to verilator instead.

Signed-off-by: Anton Blanchard <anton@linux.ibm.com>
Michael Neuling 77c03e5d42
Merge pull request from antonblanchard/hello-world-in-8k
Reduce hello_world footprint to fit in 8kB
Anton Blanchard 605010e33d Fix ghdl warning due to variable shadowing in icache
Fix a couple of ghdl warnings:

icache.vhdl:387:21⚠️ declaration of "i" hides constant "i" [-Whide]
icache.vhdl:400:17⚠️ declaration of "i" hides constant "i" [-Whide]

Signed-off-by: Anton Blanchard <anton@linux.ibm.com>
Anton Blanchard bc4e6b7efe Reduce hello_world footprint to fit in 8kB
When building with yosys we assume hello_world fits in 8kB. There's
enough free space that we can adjust the linker script to make it fit.

Signed-off-by: Anton Blanchard <anton@linux.ibm.com>
Michael Neuling 16da9b5ba7
Merge pull request from paulusmack/master
Sundry bug fixes, plus implement mtmsr
Michael Neuling b60026e7c1
Merge pull request from umarcor/containers
makefile: update synthesis containers
Michael Neuling d839037f0b
Merge pull request from umarcor/ci/containers
ci: use job.container
umarcor 93b2987b19 ci: use job.container
Signed-off-by: umarcor <unai.martinezcorral@ehu.eus>
umarcor de808d7a6a makefile: update synthesis containers
Signed-off-by: umarcor <unai.martinezcorral@ehu.eus>
umarcor d05737833e makefile: whitespace cleanup
Signed-off-by: umarcor <unai.martinezcorral@ehu.eus>
Paul Mackerras 29fabeb12e tests/misc: Add a test for correct CTR and LR updating by branches
This adds a test with a bdnzl followed immediately by a bdnz, to check
that CTR and LR both get evaluated and written back correctly in this
situation.

Signed-off-by: Paul Mackerras <paulus@ozlabs.org>