The pp_fifo decides whether top = bottom means empty or full based
on whether the previous operation was a push or a pop.
If the fifo performs both in one cycle, it sets the previous op to
pop. That means that a full fifo being added a character and removed
one at the same time becomes empty.
Instead, just leave the previous op alone. If the fifo was empty, it
remains so, if it was full ditto.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
console.c goes to a new lib/ where we'll store other general utilities
and console.h goes to include/
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
It makes things a bit more standard and a bit nicer to read
without all those strlen(). Also console.c takes care of adding
the carriage returns before the linefeeds.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Make putchar() match a standard prototype and add puts()
Also make puts() add carriage returns before linefeeds so the
users don't have to do it all over the place.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
This adds support for initializing the memory controller from microwatt
rather than using a built-in RiscV processor. This might require some
fixes to LiteX and LiteDRAM (they haven't been merged as of this commit
yet).
This is enabled in the shipped generated files and can be changed via
modifying the generator script to pass False to "mw_init"
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
This uses the new header files for register definitions and
extracts the core frequency from syscon rather than hard coding it.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
This contains C definitions for various Microwatt internal MMIOs
and a set of accessors.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
These provides some info about the SoC (though it's still somewhat
incomplete and needs more work, see comments).
There's also a control register for selecting DRAM vs. BRAM at 0
(and for soft-resetting the SoC but that isn't wired up yet).
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
The old toplevel.vhdl becomes top-generic.vhdl, which is to be used
by platforms that do not have a litedram option.
Arty has its own top-arty.vhdl which supports litedram and is now
hooked up
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
An external signal can control whether the core will start
executing at the standard or the alternate reset address.
This will be used when litedram is initialized by microwatt
itself, to route the reset to the built-in init code secondary
block RAM.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
This comes in two parts:
- A generator script which uses LiteX to generate litedram cores
along with their init files for various boards (currently Arty and
Nexys-video). This comes with configs for arty and nexys_video.
- A fusesoc "generator" which uses pre-generated litedram cores
The generation process is manual on purpose. This include pre-generated
cores for the two above boards.
This is done so that one doesn't have to install LiteX to build
microwatt. In addition, the generator script or wrapper vhdl tend to
break when LiteX changes significantly which happens.
This is still rather standalone and hasn't been plumbed into the SoC
or the FPGA toplevel files yet.
At this point LiteDRAM self-initializes using a built-in VexRiscv
"Minimum" core obtained from LiteX and included in this commit. There
is some plumbing to generate and cores that are initialized by Microwatt
directly but this isn't working yet and so isn't enabled yet.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
The icache would still spit out an instruction which could
cause a 0x700 instead of a reset.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
LiteDRAM at the moment pretty much enforces 100Mhz, and our software
isn't quite yet adaptable, so switch out default to 100Mhz accross
the board. Recent timing improvements should make it a non-issue.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
During slow instructions such as multiply or divide, if a decrementer
(or other asynchronous) interrupt becomes pending, it disrupts the
logic that keeps stall asserted until the end of the slow
instruction, and the interrupt logic starts trying to deliver the
interrupt before the slow instruction has finished.
To fix that, make the interrupt logic wait until it sees e_in.valid
set before setting exception to 1.
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
We can hit the assert for req_op = OP_STORE_HIT and reloading in the
case of dcbz, since it looks like a store. Therefore we need to
exclude that case from the assert.
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
This adds a test that tries to execute various privileged instructions
with MSR[PR] = 1. This also incidentally tests some of the MSR bit
manipulations.
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
This adds logic to dcache and loadstore1 to implement dcbz. For now
it zeroes a single cache line (by default 64 bytes), not 128 bytes
like IBM Power processors do.
The dcbz operation is performed much like a load miss, except that
we are writing zeroes to memory instead of reading. As each ack
comes back, we write zeroes to the BRAM instead of data from memory.
In this way we zero the line in memory and also zero the line of
cache memory, establishing the line in the cache if it wasn't already
resident. If it was already resident then we overwrite the existing
line in the cache.
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
In preparation for adding a TLB to the dcache, this plumbs the
insn_type from execute1 through to loadstore1, so that we can have
other operations besides loads and stores (e.g. tlbie) going to
loadstore1 and thence to the dcache. This also plumbs the unit field
of the decode ROM from decode2 through to execute1 to simplify the
logic around which ops need to go to loadstore1.
The load and store data formatting are now not conditional on the
op being OP_LOAD or OP_STORE. This eliminates the inferred latches
clocked by each of the bits of r.op that we were getting previously.
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
This adds logic to execute1 to check, when MSR[PR] = 1, whether each
instruction arriving to be executed is a privileged instruction.
If it is, a privileged-instruction type program interrupt is generated.
For the mtspr and mfspr instructions, we need to look at bit 20 of the
instruction (bit 4 of the SPR number) to determine if the SPR is
privileged.
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
This makes our treatment of the MSR conform better with the ISA.
- On reset, initialize the MSR to have the SF and LE bits set and
all the others reset. For good measure initialize r properly too.
- Fix the bit numbering in msr_copy (the code was using big-endian
bit numbers, not little-endian).
- Use constants like MSR_EE to index MSR bits instead of expressions
like '63 - 48', for readability.
- Set MSR[SF, LE] and clear MSR[PR, IR, DR, RI] on interrupts.
- Copy the relevant fields for rfid instead of using msr_copy, because
the partial function fields of the MSR should be left unchanged,
not zeroed. Our implementation of rfid is like the architecture
description of hrfid, because we don't implement hypervisor mode.
- Return the whole MSR for mfmsr.
- Implement the L field for mtmsrd (L=1 copies just EE and RI).
- For mtmsrd with L=0, leave out the HV, ME and LE bits as per the arch.
- For mtmsrd and rfid, if PR ends up set, then also set EE, IR and DR
as per the arch.
- A few other minor tidyups (no semantic change).
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
Checks interrupt masking and priorities.
Adds to `make test_xics` which is run in `make check` also.
Signed-off-by: Michael Neuling <mikey@neuling.org>
New unified ICP and ICS XICS compliant interrupt controller.
Configurable number of hardware sources.
Fixed hardware source number based on hardware line taken. All
hardware interrupts are a fixed priority. Level interrupts supported
only.
Hardwired to 0xc0004000 in SOC (UART is kept at 0xc0002000).
Signed-off-by: Michael Neuling <mikey@neuling.org>
This fixes a bug in the logic where we would still send a load
or store instruction to loadstore1 even though we have decided
to take an asynchronous interrupt.
Reported-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
Benjamin Herrenschmidt
Paul Mackerras
Michael Neuling