This implements fmadd, fmsub, fnmadd, fnmsub and their
single-precision counterparts. The single-precision versions operate
the same as the double-precision versions until the final rounding and
overflow/underflow steps.
This adds an S register to store the low bits of the product. S
shifts into R on left shifts, and can be negated, but doesn't do any
other arithmetic.
This adds a test for the double-precision versions of these
instructions.
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
This implements the floating square-root calculation using a table
lookup of the inverse square root approximation, followed by three
iterations of Goldschmidt's algorithm, which gives estimates of both
sqrt(FRB) and 1/sqrt(FRB). Then the residual is calculated as
FRB - R * R and that is multiplied by the 1/sqrt(FRB) estimate to get
an adjustment to R. The residual and the adjustment can be negative,
and since we have an unsigned multiplier, the upper bits can be wrong.
In practice the adjustment fits into an 8-bit signed value, and the
bottom 8 bits of the adjustment product are correct, so we sign-extend
them, divide by 4 (because R is in 10.54 format) and add them to R.
Finally the residual is calculated again and compared to 2*R+1 to see
if a final increment is needed. Then the result is rounded and
written back.
This implements fsqrts as fsqrt, but with rounding to single precision
and underflow/overflow calculation using the single-precision exponent
range. This could be optimized later.
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
This implements frsqrte by table lookup. We first normalize the input
if necessary and adjust so that the exponent is even, giving us a
mantissa value in the range [1.0, 4.0), which is then used to look up
an entry in a 768-entry table. The 768 entries are appended to the
table for reciprocal estimates, giving a table of 1024 entries in
total. frsqrtes is implemented identically to frsqrte.
The estimate supplied is accurate to 1 part in 1024 or better.
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
This just returns the value from the inverse lookup table. The result
is accurate to better than one part in 512 (the architecture requires
1/256).
This also adds a simple test, which relies on the particular values in
the inverse lookup table, so it is not a general test.
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
This implements floating-point division A/B by a process that starts
with normalizing both inputs if necessary. Then an estimate of 1/B
from a lookup table is refined by 3 Newton-Raphson iterations and then
multiplied by A to get a quotient. The remainder is calculated as
A - R * B (where R is the result, i.e. the quotient) and the remainder
is compared to 0 and to B to see whether the quotient needs to be
incremented by 1. The calculations of 1 / B are done with 56 fraction
bits and intermediate results are truncated rather than rounded,
meaning that the final estimate of 1 / B is always correct or a little
bit low, never too high, and thus the calculated quotient is correct
or 1 unit too low. Doing the estimate of 1 / B with sufficient
precision that the quotient is always correct to the last bit without
needing any adjustment would require many more bits of precision.
This implements fdivs by computing a double-precision quotient and
then rounding it to single precision. It would be possible to
optimize this by e.g. doing only 2 iterations of Newton-Raphson and
then doing the remainder calculation and adjustment at single
precision rather than double precision.
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
This implements the fmul and fmuls instructions.
For fmul[s] with denormalized operands we normalize the inputs
before doing the multiplication, to eliminate the need for doing
count-leading-zeroes on P. This adds 3 or 5 cycles to the
execution time when one or both operands are denormalized.
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
This implements fctiw, fctiwz, fctiwu, fctiwuz, fctid, fctidz, fctidu
and fctiduz, and adds tests for them.
There are some subtleties around the setting of the inexact (XX) and
invalid conversion (VXCVI) flags in the FPSCR. If the rounded value
ends up being out of range, we need to set VXCVI and not XX. For a
conversion to unsigned word or doubleword of a negative value that
rounds to zero, we need to set XX and not VXCVI.
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
This implements fcfid, fcfidu, fcfids and fcfidus, which convert
64-bit integer values in an FPR into a floating-point value.
This brings in a lot of the datapath that will be needed in
future, including the shifter, adder, mask generator and
count-leading-zeroes logic, along with the machinery for rounding
to single-precision or double-precision, detecting inexact results,
signalling inexact-result exceptions, and updating result flags
in the FPSCR.
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
This implements fmr, fneg, fabs, fnabs and fcpsgn and adds tests
for them.
This adds logic to unpack and repack floating-point data from the
64-bit packed form (as stored in memory and the register file) into
the unpacked form in the fpr_reg_type record. This is not strictly
necessary for fmr et al., but will be useful for when we do actual
arithmetic.
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
This tests mffs, mtfsf and the generation of floating-point type
program interrupts that occur as a result of mtfsf.
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
This tests that floating-point unavailable exceptions occur as expected
on FP loads and stores, and that the simple FP loads and stores appear
to give reasonable results.
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
This checks that the instructions seem to update memory as expected,
and also that they generate alignment interrupts when necessary.
We don't check whether the memory update is atomic as we don't have
SMP yet.
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
The tests were using MSR values that did not have MSR_SF or MSR_LE
set. Fix this so that the test still works when 32-bit and BE modes
are implemented.
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
The PVR is a privileged read-only SPR. Test reading and writing in both
supervisor and problem state. In supervisor state reading returns
microwatt's assigned PVR number and writing is a noop. In problem state
both reading and writing cause privileged instruction interrupts.
Signed-off-by: Jordan Niethe <jniethe5@gmail.com>
Use a more generic console_init() instead of potato_uart_init(),
and do the same for interrupt control. There should be no
change in behaviour.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
This makes the ICS support less than the 8 architected bits
and sets the soc to use 3 bits by default.
All the supported bits set translates to "masked" (and will read
back at 0xff), any small value is used as-is.
Linux doesn't use priorities above 5, so this is a way to save
silicon. The number of supported priority bits is exposed to the
OS via the config register.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Move the external interrupt generation to a separate module
"ICS" (source controller) which a register per source containing
currently only the priority control.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
That's how Linux expects it. This also simplifies the
register access implementation since the bit fields now
align properly regardless of the access size.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Currently the test writes to the XICS and then checks that the
expected interrupt has happened. This turns into a stbcix
instruction followed immediately by a load from the variable that
indicates whether an interrupt has happened. It is possible for
it to take a few cycles for the store to reach the XICS and the
interrupt request signal to come back to the core, particularly
with improvements to the load/store unit and dcache.
This therefore adds a delay between storing to the XICS and
checking for the occurrence of an interrupt, so as to give the
signals time to propagate. The delay loop does an arbitrary 10
iterations, and each iteration does two loads and one store to
(cacheable) memory.
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
The two tests obtain NIA with bl+mflr+addi and then compare it
against addpcis with the minimum and maximum immediate operand values.
They were also tested on a real POWER9 system (in userspace) for good
measure.
Signed-off-by: Shawn Anastasio <shawn@anastas.io>
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>
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>
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 adds the PID register and repurposes SPR 720 as the PRTBL
register, which points to the base of the process table. There
doesn't seem to be any point to implementing the partition table given
that we don't have hypervisor mode.
The MMU caches entry 0 of the process table internally (in pgtbl3)
plus the entry indexed by the value in the PID register (pgtbl0).
Both caches are invalidated by a tlbie[l] with RIC=2 or by a move to
PRTBL. The pgtbl0 cache is invalidated by a move to PID. The dTLB
and iTLB are cleared by a move to either PRTBL or PID.
Which of the two page table root pointers is used (pgtbl0 or pgtbl3)
depends on the MSB of the address being translated. Since the segment
checking ensures that address(63) = address(62), this is sufficient to
map quadrants 0 and 3.
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
Since setting MSR[PR] = 1 forces instruction translation on, we need
to set up translations for the problem state code to use.
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
This adds tests of instruction translation to the mmu test.
This also clears the BSS and improves the linker script.
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
This adds tests to check that the MMU and dTLB are translating
addresses and checking permissions correctly.
We use a simple 2-level radix tree. The radix tree maps 2GB of
address space and has a 1024-entry page directory pointing to
512-entry page table pages.
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>
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>
Paul Mackerras
Jordan Niethe
Michael Neuling