Anton Blanchard [Sun, 13 Oct 2019 01:59:14 +0000 (12:59 +1100)]
decode: Handle icbi
We will need a proper handler for icbi, but in the meantime treat it
as a nop.
Signed-off-by: Anton Blanchard <anton@linux.ibm.com>
Anton Blanchard [Sat, 12 Oct 2019 11:23:10 +0000 (22:23 +1100)]
Merge pull request #92 from paulusmack/divider
Divider
Anton Blanchard [Sat, 12 Oct 2019 11:18:37 +0000 (22:18 +1100)]
Merge pull request #91 from tgingold/gpr-file-fix
Fix register file size (there are 32 gprs).
Paul Mackerras [Fri, 11 Oct 2019 04:16:47 +0000 (15:16 +1100)]
divider: Return 0 for invalid and overflow cases, like P9 does
This adds logic to detect the cases where the quotient of the
division overflows the range of the output representation, and
return all zeroes in those cases, which is what POWER9 does.
To do this, we extend the dividend register by 1 bit and we do
an extra step in the division process to get a 2^64 bit of the
quotient, which ends up in the 'overflow' signal. This catches all
the cases where dividend >= 2^64 * divisor, including the case
where divisor = 0, and the divde/divdeu cases where |RA| >= |RB|.
Then, in the output stage, we also check that the result fits in
the representable range, which depends on whether the division is
a signed division or not, and whether it is a 32-bit or 64-bit
division. If dividend >= 2^64 or the result doesn't fit in the
representable range, write_data is set to 0 and write_cr_data to
0x20000000 (i.e. cr0.eq = 1).
POWER9 sets the top 32 bits of the result to zero for 32-bit signed
divisions, and sets CR0 when RC=1 according to the 64-bit value
(i.e. CR0.LT is always 0 for 32-bit signed divisions, even if the
32-bit result is negative). However, modsw with a negative result
sets the top 32 bits to all 1s. We follow suit.
This updates divider_tb to check the invalid cases as well as the
valid case.
This also fixes a small bug where the reset signal for the divider
was driven from rst when it should have been driven from core_rst.
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
Paul Mackerras [Sat, 12 Oct 2019 05:15:20 +0000 (16:15 +1100)]
decode2: Fix 32-bit flag passed to divider
Previously the 32-bit flag passed to the divider was always wrong;
this fixes it.
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
Tristan Gingold [Sat, 12 Oct 2019 04:56:32 +0000 (06:56 +0200)]
Fix register file size (there are 32 gprs).
Anton Blanchard [Fri, 11 Oct 2019 05:47:37 +0000 (16:47 +1100)]
Merge pull request #84 from classilla/master
Add logo
Anton Blanchard [Fri, 11 Oct 2019 05:46:03 +0000 (16:46 +1100)]
Merge pull request #89 from mikey/gitignore
Update gitignore for new test bench build files
Anton Blanchard [Fri, 11 Oct 2019 05:45:45 +0000 (16:45 +1100)]
Merge pull request #90 from antonblanchard/newcrf-inferred-latch
Don't infer latch for newcrf
Anton Blanchard [Fri, 11 Oct 2019 05:31:14 +0000 (16:31 +1100)]
Don't infer latch for newcrf
Always initialize newcrf to avoid inferring a latch.
Signed-off-by: Anton Blanchard <anton@linux.ibm.com>
Michael Neuling [Fri, 11 Oct 2019 05:02:04 +0000 (16:02 +1100)]
Update gitignore for new test bench build files
Just ignore all *_tb files
Signed-off-by: Michael Neuling <mikey@neuling.org>
Anton Blanchard [Thu, 10 Oct 2019 10:29:06 +0000 (21:29 +1100)]
Merge pull request #87 from antonblanchard/cmod-a7-freq
Fix cmod-a7 frequency
Anton Blanchard [Thu, 10 Oct 2019 09:59:49 +0000 (20:59 +1100)]
Fix cmod-a7 frequency
The cmod-a7 is ignoring the clk_frequency parameter and running at
100 MHz. Fix it.
Signed-off-by: Anton Blanchard <anton@linux.ibm.com>
Anton Blanchard [Thu, 10 Oct 2019 09:32:47 +0000 (20:32 +1100)]
Merge pull request #86 from antonblanchard/outstanding-range
Limit outstanding range
Anton Blanchard [Thu, 10 Oct 2019 06:56:55 +0000 (17:56 +1100)]
Merge pull request #85 from antonblanchard/leadingzeroes-fix
Fix count-leading/trailing-zeroes
Anton Blanchard [Thu, 10 Oct 2019 06:47:15 +0000 (17:47 +1100)]
Merge pull request #79 from deece/uart_address
Tighten UART address
Anton Blanchard [Thu, 10 Oct 2019 06:14:55 +0000 (17:14 +1100)]
Limit outstanding range
outstanding can only ever be -1 to 2 at the moment (0 or 1 on a
rising clock edge). Vivado is synthesizing a much wider adder
which is silly. Constrain it with a range statement. This should
be good for timing and saves us about 85 LUTs.
This will get relaxed when we add more pipelining, but only by a
few bits.
Signed-off-by: Anton Blanchard <anton@linux.ibm.com>
Anton Blanchard [Thu, 10 Oct 2019 03:36:23 +0000 (14:36 +1100)]
Fix count-leading/trailing-zeroes
The current code simulates correctly, but produces miscompares when synthesized
onto an FPGA. On closer inspection GHDL synthesis complains about inferred
latches and there does seem to be issues.
Convert it to variables that are always initialized to zero at the start of the
process.
Fixes: 24a4a796ce1e ("execute: Consolidate count-leading/trailing-zeroes implementations")
Signed-off-by: Anton Blanchard <anton@linux.ibm.com>
Cameron Kaiser [Wed, 9 Oct 2019 04:00:00 +0000 (21:00 -0700)]
Add logo to README.md
Signed-off-by: Cameron Kaiser <classilla@floodgap.com>
Cameron Kaiser [Wed, 9 Oct 2019 03:57:20 +0000 (20:57 -0700)]
Add title image
Signed-off-by: Cameron Kaiser <classilla@floodgap.com>
Anton Blanchard [Wed, 9 Oct 2019 01:33:17 +0000 (12:33 +1100)]
Merge pull request #83 from paulusmack/logical
execute: Consolidate count-leading/trailing-zeroes implementations
Anton Blanchard [Wed, 9 Oct 2019 00:49:24 +0000 (11:49 +1100)]
Merge pull request #81 from antonblanchard/logical
Consolidate logical instructions
Anton Blanchard [Wed, 9 Oct 2019 00:47:30 +0000 (11:47 +1100)]
Merge pull request #82 from antonblanchard/icache-set-assoc
A new set associative icache from Ben
Paul Mackerras [Tue, 8 Oct 2019 21:55:43 +0000 (08:55 +1100)]
execute: Consolidate count-leading/trailing-zeroes implementations
This adds combinatorial logic that does 32-bit and 64-bit count
leading and trailing zeroes in one unit, and consolidates the
four instructions under a single OP_CNTZ opcode.
This saves 84 slice LUTs on the Arty A7-100.
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
Anton Blanchard [Tue, 8 Oct 2019 07:46:01 +0000 (18:46 +1100)]
Consolidate logical instructions
Consolidate and/andc/nand, or/orc/nor and xor/eqv, using a common
invert on the input and output. This saves us about 200 LUTs.
Signed-off-by: Anton Blanchard <anton@linux.ibm.com>
Alastair D'Silva [Thu, 3 Oct 2019 00:16:53 +0000 (10:16 +1000)]
Tighten UART address
The current scheme has UART0 repeating throughout the UART address range.
This patch tightens the address checking so that it only occurs once.
Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
Benjamin Herrenschmidt [Wed, 2 Oct 2019 12:17:31 +0000 (22:17 +1000)]
icache: Set associative icache
This adds support for set associativity to the icache. It can still
be direct mapped by setting NUM_WAYS to 1.
The replacement policy uses a simple tree-PLRU for each set.
This is only lightly tested, tests pass but I have to double check
that we are using the ways effectively and not creating duplicates.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Benjamin Herrenschmidt [Wed, 2 Oct 2019 09:06:53 +0000 (19:06 +1000)]
plru: Add a simple PLRU module
Tested in sim only for now
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Benjamin Herrenschmidt [Wed, 2 Oct 2019 06:17:42 +0000 (16:17 +1000)]
fetch2: Remove blank line
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Benjamin Herrenschmidt [Mon, 30 Sep 2019 08:17:10 +0000 (18:17 +1000)]
icache: Use narrower block RAMs
We only ever access the cache memory for at most the wishbone bus
width at a time. So having the BRAMs organized as a cache-line-wide
port is a waste of resources.
Instead, use a wishbone-wide memory and store a line as consecutive
rows in the BRAM.
This significantly improves BRAM usage in the FPGA as we can now use
more rows in the BRAM blocks. It also saves a few LUTs and muxes.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Benjamin Herrenschmidt [Fri, 27 Sep 2019 03:23:56 +0000 (13:23 +1000)]
fetch/icache: Fit icache in BRAM
The goal is to have the icache fit in BRAM by latching the output
into a register. In order to avoid timing issues , we need to give
the BRAM a full cycle on reads, and thus we souce the BRAM address
directly from fetch1 latched NIA.
(Note: This will be problematic if/when we want to hash the address,
we'll probably be better off having fetch1 latch a fully hashed address
along with the normal one, so the icache can use the former to address
the BRAM and pass the latter along)
One difficulty is that we cannot really stall the icache without adding
more combo logic that would break the "one full cycle" BRAM model. This
means that on stalls from decode, by the time we stall fetch1, it has
already gone to the next address, which the icache is already latching.
We work around this by having a "stash" buffer in fetch2 that will stash
away the icache output on a stall, and override the output of the icache
with the content of the stash buffer when unstalling.
This requires a rewrite of the stop/step debug logic as well. We now
do most of the hard work in fetch1 which makes more sense.
Note: Vivado is still not inferring an built-in output register for the
BRAMs. I don't want to add another cycle... I don't fully understand why
it wouldn't be able to treat current_row as such but clearly it won't. At
least the timing seems good enough now for 100Mhz, possibly more.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Benjamin Herrenschmidt [Tue, 1 Oct 2019 04:24:07 +0000 (14:24 +1000)]
fetch1: Simplify a bit
There is no need to have two different state records
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Benjamin Herrenschmidt [Wed, 25 Sep 2019 06:50:24 +0000 (16:50 +1000)]
icache: Reformat icache
No code change
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Anton Blanchard [Mon, 7 Oct 2019 23:20:22 +0000 (10:20 +1100)]
Merge pull request #78 from paulusmack/new-decode
New decode
Paul Mackerras [Mon, 7 Oct 2019 07:26:11 +0000 (18:26 +1100)]
Add a rotate/mask/shift unit and use it in execute1
This adds a new entity 'rotator' which contains combinatorial logic
for rotating and masking 64-bit values. It implements the operations
of the rlwinm, rlwnm, rlwimi, rldicl, rldicr, rldic, rldimi, rldcl,
rldcr, sld, slw, srd, srw, srad, sradi, sraw and srawi instructions.
It consists of a 3-stage 64-bit rotator using 4:1 multiplexors at
each stage, two mask generators, output logic and control logic.
The insn_type_t values used for these instructions have been reduced
to just 5: OP_RLC, OP_RLCL and OP_RLCR for the rotate and mask
instructions (clear both left and right, clear left, clear right
variants), OP_SHL for left shifts, and OP_SHR for right shifts.
The control signals for the rotator are derived from the opcode
and from the is_32bit and is_signed fields of the decode_rom_t.
The rotator is instantiated as an entity in execute1 so that we can
be sure we only have one of it.
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
Paul Mackerras [Sun, 6 Oct 2019 04:21:27 +0000 (15:21 +1100)]
Generalize the mul_32bit and mul_signed fields of decode_rom_t
This changes the names of the mul_32bit and mul_signed fields of
decode_rom_t to is_32bit and is_signed, so they can be used with
other types of operations besides multiplies.
This plumbs the is_32bit and is_signed flags down into execute1,
though they are not used at this point.
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
Paul Mackerras [Fri, 4 Oct 2019 09:26:37 +0000 (19:26 +1000)]
decode: Avoid multiplexing from instruction reg fields to regfile address ports
This aims to simplify the logic between the instruction image and
the register file read address ports and reduce the size of the decode
tables. With this patch, the input_reg_a column of the decode tables
can only select RA or zeroes, the input_reg_b column can only select
RB or a constant (0, -1, or an immediate value from the instruction),
and the input_reg_c columns can only select RS or zeroes.
That means that the rotate/shift/logical ops now have their first
input coming in via the input_reg_c column. That means we need to
add a read_data3 field to the Decode2ToExecuteType record, but that
will go away again when we split out the rotate/mask/logical ops to
their own unit.
As a related but not tightly connected change, this patch also sets
the read1_enable signal to the register file be 0 when RA=0 and the
input_reg_a for the instruction is RA_OR_ZERO (previously it was 1).
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
Paul Mackerras [Fri, 4 Oct 2019 06:11:21 +0000 (16:11 +1000)]
Consolidate add/subtract instructions into a single op
All of the PPC add and subtract instructions, including carrying
and extended versions, do much the same arithmetic operation:
result = (I xor A) + B + C
where A is the value from RA, I provides a logical inversion of A
(i.e. I is 0 or -1), B is either from RB or is a constant 0 or -1,
and C is 0, 1 or the carry bit from XER (CA).
To consolidate all the add/subtract instructions into a single
OP_ADD, we add a column to decode_rom_t to indicate when A should
be inverted, and change the input_carry field to a 3-state selector
to select C in the equation above.
This also adds a new "CONST_M1" value for input_reg_b_t to indicate
that B is a constant -1. This allows us to implement addme and
subfme.
The addex instruction appears not to exist, so the comments referring
to it are removed.
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
Anton Blanchard [Fri, 4 Oct 2019 00:32:13 +0000 (10:32 +1000)]
Merge pull request #80 from antonblanchard/misc
Reduce register file footprint
Paul Mackerras [Thu, 3 Oct 2019 22:25:53 +0000 (08:25 +1000)]
decode: Make all update-form indexed loads and stores use RA_OR_ZERO
Experimentation on POWER9 indicates that the invalid form of lbzux
with RA=0 uses just RB as the address, not R0 + RB. Extrapolating
this to all update-form loads and stores with RA=0, change all the
update-form loads and stores to use RA_OR_ZERO rather than RA.
This then means that all decode ROM entries with insn_type = LDST
have input_reg_a = RA_OR_ZERO.
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
Benjamin Herrenschmidt [Thu, 3 Oct 2019 02:38:49 +0000 (12:38 +1000)]
register_file: Move GPRs into distributed RAM
The register file is currently implemented as a whole pile of individual
1-bit registers instead of LUT memory which is a huge waste of FPGA
space.
This is caused by the output signal exposing the register file to the
outside world for simulation debug.
This removes that output, and moves the dumping of the register file
to the register file module itself. This saves about 8% of fpga on
the little Arty A7-35T.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Paul Mackerras [Wed, 2 Oct 2019 12:21:09 +0000 (22:21 +1000)]
decode: Remove const fields from decode_rom_t
The const* fields of decode_rom_t drove multiplexers in decode2 that
picked out various instruction fields and put them into the const*
fields of the Decode2ToExecute1Type record, from where they were
used in execute1. However, the code in execute1 can just as easily
use the appropriate fields of the original instruction word, since
that is now available in execute1. This therefore changes the
code to do that, resulting in smaller decode tables.
Suggested-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
Benjamin Herrenschmidt [Tue, 1 Oct 2019 23:58:44 +0000 (09:58 +1000)]
debug/sim: Make connect/disconnect messages quieter
Those don't need to go to stderr, send them to stdout instead
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Paul Mackerras [Tue, 1 Oct 2019 05:49:07 +0000 (15:49 +1000)]
decode: Fix larx/stcx instructions to use RA_OR_ZERO not RA
The l?arx and st?cx. instructions are defined to use the normal indexed
mode address calculations, i.e. (RA|0) + RB. Fix their entries in the
decode table to say RA_OR_ZERO rather than RA.
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
Paul Mackerras [Mon, 30 Sep 2019 05:03:06 +0000 (15:03 +1000)]
decode: Index minor op table with insn bits for opcode 31
This changes decode_op_31_array from being indexed by a ppc_insn_t
(which is derived from the instruction word by a whole series of
if/elsif statements) to being indexed directly by bits 10...1 of
the instruction word. With this we no longer need ppc_insn.
This then means that the decode1 stage doesn't distinguish between
mfcr and mfocrf, or between mtcrf and mtocrf, since those are
distinguished by the value in bit 20 of the instruction. To
accommodate that, execute1 changes so that the one op value (OP_MFCR)
does either the mfcr or the mfocrf behaviour depending on bit 20
of the instruction word; and similarly for mtcrf/mtocrf.
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
Paul Mackerras [Sun, 29 Sep 2019 06:41:52 +0000 (16:41 +1000)]
decode: Index minor op table with insn bits for opcode 30
This comprises the 64-bit rotate and mask instructions. In order to
reduce the table index to 3 bits, we combine rldcl and rdlcr into a
single op (OP_RLDCX), and choose the right mask at execute time based
on bit 1 of the instruction word.
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
Paul Mackerras [Sun, 29 Sep 2019 06:26:07 +0000 (16:26 +1000)]
decode: Index minor op table with insn bits for opcode 19
This changes the decoding of major opcode 19 from using the ppc_insn_t
index to using bits of the instruction word directly. Opcode 19 has
a 10-bit minor opcode field (bits 10..1) but the space is sparsely
filled. Therefore we index a table of single-bit entries with the
10-bit minor opcode to filter out the illegal minor opcodes, and
index a table using just 3 bits -- 5, 3 and 2 -- of the instruction
to get the decode entry. This groups together all the instructions
in 4 columns of the opcode map as a single entry. That means that
mcrf and all the CR logical ops get grouped together, and bcctr, bclr
and bctar get grouped together. At present the CR logical ops are not
implemented, so their grouping has no impact.
The code for bclr and bcctr in execute1 is now common, using a single
op, and it now determines the branch address by looking at bit 10 of
the instruction word at execute time.
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
Paul Mackerras [Sat, 28 Sep 2019 23:17:39 +0000 (09:17 +1000)]
decode: Start moving towards decoding by major opcode first
With this, we have a table for most major opcodes and separate
tables for each major opcode that has further decoding required.
These tables are still mostly indexed by the ppc_insn_t values,
however.
A few things are still decoded completely at the top level: nop,
attn and sim_config.
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
Paul Mackerras [Sat, 28 Sep 2019 04:43:46 +0000 (14:43 +1000)]
decode: Push mtspr/mfspr register decoding down into execute1
Instead of doing mfctr, mflr, mftb, mtctr, mtlr as separate ops,
just pass down mfspr and mtspr ops with the spr number and let
execute1 decode which SPR we're addressing. This will help reduce
the number of instruction bits decode1 needs to look at.
In fact we now pass down the whole instruction from decode2 to
execute1. We will need more bits of the instruction in future,
and the tools should just optimize away any that we don't end
up using. Since the 'aa' bit was just a copy of an instruction
bit, we can now remove it from the record.
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
Benjamin Herrenschmidt [Tue, 24 Sep 2019 14:09:35 +0000 (00:09 +1000)]
Add MCRF instruction
Hopefully it's not too timing catastrophic. The variable newcrf will
be handy for the other CR ops when we implement them I suspect.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Benjamin Herrenschmidt [Tue, 24 Sep 2019 05:47:25 +0000 (15:47 +1000)]
Implement absolute branches
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Anton Blanchard [Mon, 30 Sep 2019 08:21:54 +0000 (18:21 +1000)]
Merge pull request #77 from antonblanchard/timing
A number of timing fixes
Anton Blanchard [Mon, 30 Sep 2019 08:00:41 +0000 (18:00 +1000)]
Merge pull request #76 from antonblanchard/misc
Some misc updates
Benjamin Herrenschmidt [Tue, 24 Sep 2019 04:57:34 +0000 (14:57 +1000)]
Improve PLL/MMCM clocks configuration
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>
Benjamin Herrenschmidt [Thu, 26 Sep 2019 01:09:46 +0000 (11:09 +1000)]
Don't reset JTAG request register asynchronously
There's no point and it causes Vivado to spew a pile of warnings
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Benjamin Herrenschmidt [Thu, 26 Sep 2019 00:53:55 +0000 (10:53 +1000)]
Multiply needs to be 16 stages to fix all timing issues
This seems dependent on the FPGA type/size, so we should probably
make it a toplevel generic, but for now this helps on the
Arty A7-35
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Paul Mackerras [Wed, 25 Sep 2019 10:27:08 +0000 (20:27 +1000)]
loadstore2: Do data formatting after a register stage
This moves the data formatting for read data to after a register,
instead of before, in order to improve timing. The data formatting
is now effectively combinational logic on the input side of the
writeback stage.
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
Benjamin Herrenschmidt [Mon, 30 Sep 2019 03:54:04 +0000 (13:54 +1000)]
corefile: Remove duplicate wishbone_debug_master
It's both in core and soc, it should only be in the latter
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Benjamin Herrenschmidt [Mon, 30 Sep 2019 02:56:09 +0000 (12:56 +1000)]
fpga: Arty A7's don't need multiple filesets
the XDC is identical between variants, so is the fileset
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Benjamin Herrenschmidt [Wed, 25 Sep 2019 06:42:44 +0000 (16:42 +1000)]
execute1: simplify flush_out
It's always set when f_out.redirect is set, so may as well set it once
at the end. It's all combo from the register.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Benjamin Herrenschmidt [Wed, 25 Sep 2019 01:28:20 +0000 (11:28 +1000)]
Reformat fetch2
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Benjamin Herrenschmidt [Wed, 25 Sep 2019 01:26:36 +0000 (11:26 +1000)]
Move fetch2 <-> icache definitions
To a more logical place before decode related ones
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Benjamin Herrenschmidt [Wed, 25 Sep 2019 02:48:15 +0000 (12:48 +1000)]
Remove unused pipe_stop in Fetch1ToFetch2Type
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Benjamin Herrenschmidt [Wed, 11 Sep 2019 11:18:22 +0000 (12:18 +0100)]
Fix PLL reset signal name in toplevel
It shouldn't have a _n suffix, it's active positive.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Benjamin Herrenschmidt [Tue, 24 Sep 2019 02:17:42 +0000 (12:17 +1000)]
Simplify fetch1
Do the +4 in a single place. This shouldn't cause any difference
in behaviour as these are sequential variable assignments.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Benjamin Herrenschmidt [Tue, 24 Sep 2019 02:11:24 +0000 (12:11 +1000)]
Reformat fetch1
No code change
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Benjamin Herrenschmidt [Wed, 25 Sep 2019 06:54:25 +0000 (16:54 +1000)]
Update dependency
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Anton Blanchard [Sat, 28 Sep 2019 04:32:31 +0000 (14:32 +1000)]
Merge pull request #75 from paulusmack/master
fpga: Add definitions for Arty A7-100 board
Anton Blanchard [Sat, 28 Sep 2019 04:32:14 +0000 (14:32 +1000)]
Merge pull request #74 from paulusmack/divider
Divider
Paul Mackerras [Fri, 27 Sep 2019 23:08:13 +0000 (09:08 +1000)]
fpga: Add definitions for Arty A7-100 board
These are a copy of the A7-35 definitions with 35 changed to 100.
The A7-100 uses the same .xdc file (arty_a7-35.xdc) as the A7-35
since the only difference between the two is the FPGA part; the
hardware and connections on the two boards are identical.
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
Paul Mackerras [Fri, 27 Sep 2019 22:55:08 +0000 (08:55 +1000)]
divider: Do absolute-value ops in divider instead of decode
This moves the negation of negative operands for signed divide and
modulus operations out of the decode2 stage and into the divider.
If either of the operands for a signed divide or modulus operation
is negative, the divider now takes an extra cycle to negate the
operands that are negative.
The interface to the divider now has an 'is_signed' signal rather
than a 'neg_result' signal, and the dividend and divisor can be
negative, so divider_tb had to be updated for the new interface.
The reason for doing this is that one of the worst timing violations
on the Arty A7-100 at 100MHz involved the carry chain in the adders
that did the negation of the dividend and divisor in the decode stage.
Moving the negations to a separate cycle fixes that and also seems to
reduce the total number of slice LUTs used.
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
Paul Mackerras [Wed, 25 Sep 2019 10:03:46 +0000 (20:03 +1000)]
divider: Always compute result/sresult/d_out.write_reg_data
These are intended to be combinatorial. The previous code was giving
warnings in vivado about registers/latches with no clock defined.
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
Anton Blanchard [Tue, 24 Sep 2019 23:13:18 +0000 (09:13 +1000)]
Merge pull request #73 from antonblanchard/remove-divide-patch
Remove gcc software divide patch
Anton Blanchard [Tue, 24 Sep 2019 22:03:10 +0000 (08:03 +1000)]
Remove gcc software divide patch
We have a divider, thanks to Paul.
Signed-off-by: Anton Blanchard <anton@linux.ibm.com>
Anton Blanchard [Tue, 24 Sep 2019 10:54:28 +0000 (20:54 +1000)]
Merge pull request #72 from antonblanchard/build-error
Fix build issue in dmi_dtm_dummy.vhdl
Anton Blanchard [Tue, 24 Sep 2019 10:34:52 +0000 (20:34 +1000)]
Merge pull request #71 from antonblanchard/dependencies
Update Makefile dependencies
Anton Blanchard [Tue, 24 Sep 2019 10:27:34 +0000 (20:27 +1000)]
Fix build issue in dmi_dtm_dummy.vhdl
Signed-off-by: Anton Blanchard <anton@linux.ibm.com>
Anton Blanchard [Tue, 24 Sep 2019 07:50:17 +0000 (17:50 +1000)]
Update Makefile dependencies
Signed-off-by: Anton Blanchard <anton@linux.ibm.com>
Anton Blanchard [Tue, 24 Sep 2019 07:33:21 +0000 (17:33 +1000)]
Merge branch 'divider' of https://github.com/paulusmack/microwatt
Anton Blanchard [Tue, 24 Sep 2019 07:25:44 +0000 (17:25 +1000)]
Merge pull request #70 from antonblanchard/badly-named-carry
Rename OP_SUBFC -> OP_SUBFE, OP_ADDC -> OP_ADDE
Anton Blanchard [Tue, 24 Sep 2019 06:55:09 +0000 (16:55 +1000)]
Rename OP_SUBFC -> OP_SUBFE, OP_ADDC -> OP_ADDE
These were somewhat badly named.
Signed-off-by: Anton Blanchard <anton@linux.ibm.com>
Anton Blanchard [Tue, 24 Sep 2019 06:51:03 +0000 (16:51 +1000)]
Merge pull request #69 from antonblanchard/debug-module
Merge debug module patches
Anton Blanchard [Mon, 23 Sep 2019 11:22:18 +0000 (21:22 +1000)]
Terminate test on illegal instruction
This gets the CI going again, but we will want to fix the test
harness since it's useful to be able to debug the core after it
executes an illegal instruction.
Signed-off-by: Anton Blanchard <anton@linux.ibm.com>
Anton Blanchard [Mon, 23 Sep 2019 11:20:12 +0000 (21:20 +1000)]
Fix ghdl error
I'm seeing an issue on my version of ghdl:
core.vhdl:137:24:error: actual expression must be globally static
Signed-off-by: Anton Blanchard <anton@linux.ibm.com>
Anton Blanchard [Mon, 23 Sep 2019 10:49:21 +0000 (20:49 +1000)]
Add core_debug.vhdl to fusesoc configs
Signed-off-by: Anton Blanchard <anton@linux.ibm.com>
Paul Mackerras [Mon, 23 Sep 2019 04:39:50 +0000 (14:39 +1000)]
Speed up the divider a little
This looks for cases where the next 8 bits of the quotient are obviously
going to be zero, because the top 72 bits of the 128-bit dividend
register are all zero. In those cases we shift 8 zero bits into the
quotient and increase count by 8. We only do this if count < 56.
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
Paul Mackerras [Sun, 22 Sep 2019 07:24:14 +0000 (17:24 +1000)]
Add a divider unit and a testbench for it
This adds a divider unit, connected to the core in much the same way
that the multiplier unit is connected. The division algorithm is
very simple-minded, taking 64 clock cycles for any division (even
32-bit division instructions).
The decoding is simplified by making use of regularities in the
instruction encoding for div* and mod* instructions. Instead of
having PPC_* encodings from the first-stage decoder for each of the
different div* and mod* instructions, we now just have PPC_DIV and
PPC_MOD, and the inputs to the divider that indicate what sort of
division operation to do are derived from instruction word bits.
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
Benjamin Herrenschmidt [Fri, 20 Sep 2019 06:45:26 +0000 (16:45 +1000)]
Add distclean to Makefile
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Benjamin Herrenschmidt [Mon, 16 Sep 2019 15:29:08 +0000 (16:29 +0100)]
New C based JTAG debug tool
This works with both the sim socket and urjtag, and supports the
new core functions, loading a file in memory etc...
The code still needs a lot of cleanup and a help!
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Benjamin Herrenschmidt [Tue, 10 Sep 2019 16:43:52 +0000 (17:43 +0100)]
Add core debug module
This module adds some simple core controls:
reset, stop, start, step
along with icache clear and reading the NIA and core
status bits
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org
Benjamin Herrenschmidt [Mon, 16 Sep 2019 15:28:48 +0000 (16:28 +0100)]
Add jtag support in simulation via a socket
This adds a local socket that can be used to communicate with
the debug tool (which will be committed separately) and generates
the JTAG signals.
We generate the low level JTAG signals, thus directly driving the
simulated BSCANE2, and the Xilinx DTM
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Benjamin Herrenschmidt [Tue, 10 Sep 2019 16:39:59 +0000 (17:39 +0100)]
Add DMI address decoder
And prepare signals for core DMI support
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Benjamin Herrenschmidt [Tue, 10 Sep 2019 16:31:25 +0000 (17:31 +0100)]
Wishbone debug module
This adds a debug module off the DMI (debug) bus which can act as a
wishbone master to generate read and write cycles.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Benjamin Herrenschmidt [Tue, 10 Sep 2019 16:17:59 +0000 (17:17 +0100)]
Add a debug (DMI) bus and a JTAG interface to it on Xilinx FPGAs
This adds a simple bus that can be mastered from an external
system via JTAG, which will be used to hookup various debug
modules.
It's loosely based on the RiscV model (hence the DMI name).
The module currently only supports hooking up to a Xilinx BSCANE2
but it shouldn't be too hard to adapt it to support different TAPs
if necessary.
The JTAG protocol proper is not exactly the RiscV one at this point,
though I might still change it.
This comes with some sim variants of Xilinx BSCANE2 and BUFG and a
test bench.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Benjamin Herrenschmidt [Tue, 10 Sep 2019 16:03:37 +0000 (17:03 +0100)]
Use a 3 way WB arbiter and cleanup fpga toplevel
The 3rd master is currently unused, it will host the WB debug module.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Anton Blanchard [Thu, 19 Sep 2019 12:49:41 +0000 (22:49 +1000)]
Merge pull request #66 from antonblanchard/reformat-4
More reformatting
Anton Blanchard [Thu, 19 Sep 2019 11:53:27 +0000 (21:53 +1000)]
Reformat crhelpers, and remove some stale code
Signed-off-by: Anton Blanchard <anton@linux.ibm.com>
Anton Blanchard [Thu, 19 Sep 2019 11:53:09 +0000 (21:53 +1000)]
Reformat helpers
Signed-off-by: Anton Blanchard <anton@linux.ibm.com>
Anton Blanchard [Thu, 19 Sep 2019 11:52:07 +0000 (21:52 +1000)]
Reformat insn_helpers
Signed-off-by: Anton Blanchard <anton@linux.ibm.com>
Anton Blanchard [Thu, 19 Sep 2019 11:48:22 +0000 (21:48 +1000)]
Merge pull request #65 from antonblanchard/loadstore-opt
A small loadstore optimisation, and some reformatting