linux.git/arch/powerpc/platforms/microwatt, branch vsnprintf

powerpc: Make generic_calibrate_decr() the default

2023-03-15T21:56:48+00:00

ppc_md.calibrate_decr() is a mandatory item. Its nullity is never
checked so it must be non null on all platforms.

Most platforms define generic_calibrate_decr() as their
ppc_md.calibrate_decr(). Have time_init() call
generic_calibrate_decr() when ppc_md.calibrate_decr() is NULL,
and remove default assignment from all machines.

Signed-off-by: Christophe Leroy 
Signed-off-by: Michael Ellerman 
Link: https://msgid.link/6cb9865d916231c38401ba34ad1a98c249fae135.1676711562.git.christophe.leroy@csgroup.eu

powerpc/platforms: Use 'compatible' property for simple cases

2023-03-14T13:52:10+00:00

Use the new 'compatible' property for simple cases.

checkpatch complains about the new compatible being undocumented
but in reality nothing is new so just ignore it for the time
being.

Signed-off-by: Christophe Leroy 
Signed-off-by: Michael Ellerman 
Link: https://msgid.link/6cb9865d916231c38401ba34ad1a98c249fae135.1676711562.git.christophe.leroy@csgroup.eu

random: remove CONFIG_ARCH_RANDOM

2022-07-18T13:03:37+00:00

When RDRAND was introduced, there was much discussion on whether it
should be trusted and how the kernel should handle that. Initially, two
mechanisms cropped up, CONFIG_ARCH_RANDOM, a compile time switch, and
"nordrand", a boot-time switch.

Later the thinking evolved. With a properly designed RNG, using RDRAND
values alone won't harm anything, even if the outputs are malicious.
Rather, the issue is whether those values are being *trusted* to be good
or not. And so a new set of options were introduced as the real
ones that people use -- CONFIG_RANDOM_TRUST_CPU and "random.trust_cpu".
With these options, RDRAND is used, but it's not always credited. So in
the worst case, it does nothing, and in the best case, maybe it helps.

Along the way, CONFIG_ARCH_RANDOM's meaning got sort of pulled into the
center and became something certain platforms force-select.

The old options don't really help with much, and it's a bit odd to have
special handling for these instructions when the kernel can deal fine
with the existence or untrusted existence or broken existence or
non-existence of that CPU capability.

Simplify the situation by removing CONFIG_ARCH_RANDOM and using the
ordinary asm-generic fallback pattern instead, keeping the two options
that are actually used. For now it leaves "nordrand" for now, as the
removal of that will take a different route.

Acked-by: Michael Ellerman 
Acked-by: Catalin Marinas 
Acked-by: Borislav Petkov 
Acked-by: Heiko Carstens 
Acked-by: Greg Kroah-Hartman 
Signed-off-by: Jason A. Donenfeld

powerpc/microwatt: wire up rng during setup_arch()

2022-06-18T00:19:10+00:00

The platform's RNG must be available before random_init() in order to be
useful for initial seeding, which in turn means that it needs to be
called from setup_arch(), rather than from an init call. Fortunately,
each platform already has a setup_arch function pointer, which means
it's easy to wire this up. This commit also removes some noisy log
messages that don't add much.

Fixes: c25769fddaec ("powerpc/microwatt: Add support for hardware random number generator")
Cc: stable@vger.kernel.org # v5.14+
Signed-off-by: Jason A. Donenfeld 
Reviewed-by: Christophe Leroy 
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/20220611151015.548325-2-Jason@zx2c4.com

powerpc/microwatt: add POWER9_CPU, clear PPC_64S_HASH_MMU

2021-12-09T11:41:16+00:00

Microwatt implements a subset of ISA v3.0 (which is equivalent to
the POWER9_CPU option). It is radix-only, so does not require hash
MMU support.

This saves 20kB compressed dtbImage and 56kB vmlinux size.

Signed-off-by: Nicholas Piggin 
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/20211201144153.2456614-19-npiggin@gmail.com

powerpc/64s: Make hash MMU support configurable

2021-12-09T11:40:24+00:00

This adds Kconfig selection which allows 64s hash MMU support to be
disabled. It can be disabled if radix support is enabled, the minimum
supported CPU type is POWER9 (or higher), and KVM is not selected.

Signed-off-by: Nicholas Piggin 
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/20211201144153.2456614-17-npiggin@gmail.com

powerpc: Rename PPC_NATIVE to PPC_HASH_MMU_NATIVE

2021-12-02T11:57:22+00:00

PPC_NATIVE now only controls the native HPT code, so rename it to be
more descriptive. Restrict it to Book3S only.

Signed-off-by: Nicholas Piggin 
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/20211201144153.2456614-3-npiggin@gmail.com

powerpc/microwatt: Make microwatt_get_random_darn() static

2021-11-25T00:25:34+00:00

Make microwatt_get_random_darn() static, because it can be.

Reported-by: kernel test robot 
Signed-off-by: Michael Ellerman 
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/20211118004415.1706863-1-mpe@ellerman.id.au

powerpc/microwatt: Add support for hardware random number generator

2021-06-21T11:16:32+00:00

Microwatt's hardware RNG is accessed using the DARN instruction.

Signed-off-by: Paul Mackerras 
Reviewed-by: Nicholas Piggin 
Reviewed-by: Segher Boessenkool 
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/YMwXPHlV/ZleiQUY@thinks.paulus.ozlabs.org

powerpc/microwatt: Use standard 16550 UART for console

2021-06-21T11:16:31+00:00

This adds support to the Microwatt platform to use the standard
16550-style UART which available in the standalone Microwatt FPGA.

Signed-off-by: Benjamin Herrenschmidt 
Signed-off-by: Paul Mackerras 
Reviewed-by: Segher Boessenkool 
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/YMwXGCTzedpQje7r@thinks.paulus.ozlabs.org