Many moons ago, support was added to the SMI handlers to log s0ix entry
and exit. Early iterations of firmware on Apollo Lake correctly returned
"unsupported" for this new command they did not recognize, but
unfortunately also contained a quirk where this command would cause them
to power down rather than resume from s0ix.

Fixes for this quirk were pushed out long ago, so all APL devices still
in the field should have updated firmware. As such, we no longer need to
have the s0ix_logging_enable be opt-in, where every new platform has to
add this to their kernel commandline parameters. Change it to be on by
default.

In theory we could remove the parameter altogether: updated versions of
Chrome OS containing a kernel with this change would also be coupled
with firmware that behaves properly with these commands. Eventually we
should probably do that. For now, convert this to an opt-out parameter
so there's an emergency valve for people who are deliberately running
old firmware, or as an escape hatch in case of unforeseen regressions.

Signed-off-by: Evan Green <evgreen@chromium.org>
Link: https://lore.kernel.org/r/20210401140430.1.Ie141e6044d9b0d5aba72cb08857fdb43660c54d3@changeid
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

All coreboot drivers return 0 unconditionally in their remove callback.
Also the device core ignores the return value of the struct
bus_type::remove(), so make the coreboot remove callback return void
instead of giving driver authors the illusion they could return an error
code here.

All drivers are adapted accordingly.

Signed-off-by: Uwe Kleine-König <uwe@kleine-koenig.org>
Link: https://lore.kernel.org/r/20210126215339.706021-1-uwe@kleine-koenig.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

GSMI driver uses dma_pool_* API functions for buffer allocation
because it requires that the SMI buffers are allocated within 32-bit
physical address space. However, this does not work well with IOMMU
since there is no real device and hence no domain associated with the
device.

Since this is not a real device, it does not require any device
address(IOVA) for the buffer allocations. The only requirement is to
ensure that the physical address allocated to the buffer is within
32-bit physical address space. This is because the buffers have
nothing to do with DMA at all. It is required for communication with
firmware executing in SMI mode which has access only to the bottom
4GiB of memory. Hence, this change switches to using a SLAB cache
created with SLAB_CACHE_DMA32 that guarantees that the allocation
happens from the DMA32 memory zone. All calls to dma_pool_* are
replaced with kmem_cache_*.

In addition to that, all the code for managing the dma_pool for GSMI
platform device is dropped.

Signed-off-by: Furquan Shaikh <furquan@google.com>
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20201022071550.1192947-1-furquan@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

The gsmi code does not actually rely on CONFIG_EFI_VARS, since it only
uses the efivars abstraction that is included unconditionally when
CONFIG_EFI is defined. CONFIG_EFI_VARS controls the inclusion of the
code that exposes the sysfs entries, and which has been deprecated for
some time.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>

There is a regular need in the kernel to provide a way to declare having a
dynamically sized set of trailing elements in a structure. Kernel code should
always use “flexible array members”[1] for these cases. The older style of
one-element or zero-length arrays should no longer be used[2].

[1] https://en.wikipedia.org/wiki/Flexible_array_member
[2] https://github.com/KSPP/linux/issues/21

Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>

There is a regular need in the kernel to provide a way to declare having a
dynamically sized set of trailing elements in a structure. Kernel code should
always use “flexible array members”[1] for these cases. The older style of
one-element or zero-length arrays should no longer be used[2].

[1] https://en.wikipedia.org/wiki/Flexible_array_member
[2] https://github.com/KSPP/linux/issues/21

Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>

Currently this driver is loaded if the DMI string matches coreboot
and has a proper smi_command in the ACPI FADT table, but a GSMI handler in
SMM is an optional feature in coreboot.

So probe for a SMM GSMI handler before initializing the driver.
If the smihandler leaves the calling argument in %eax in the SMM save state
untouched that generally means the is no handler for GSMI.

Signed-off-by: Arthur Heymans <arthur@aheymans.xyz>
Signed-off-by: Patrick Rudolph <patrick.rudolph@9elements.com>
Link: https://lore.kernel.org/r/20191118101934.22526-4-patrick.rudolph@9elements.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Fix a bug where the kernel module couldn't be loaded after unloading,
as the platform driver wasn't released on exit.

Signed-off-by: Arthur Heymans <arthur@aheymans.xyz>
Signed-off-by: Patrick Rudolph <patrick.rudolph@9elements.com>
Link: https://lore.kernel.org/r/20191118101934.22526-3-patrick.rudolph@9elements.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Fix a bug where the kernel module can't be loaded after it has been
unloaded as the devices are still present and conflicting with the
to be created coreboot devices.

Signed-off-by: Patrick Rudolph <patrick.rudolph@9elements.com>
Link: https://lore.kernel.org/r/20191118101934.22526-2-patrick.rudolph@9elements.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Commit 4b708b7b1a2c ("firmware: google: check if size is valid when
decoding VPD data") adds length checks, but the new vpd_decode_entry()
function botched the logic -- it adds the key length twice, instead of
adding the key and value lengths separately.

On my local system, this means vpd.c's vpd_section_create_attribs() hits
an error case after the first attribute it parses, since it's no longer
looking at the correct offset. With this patch, I'm back to seeing all
the correct attributes in /sys/firmware/vpd/...

Fixes: 4b708b7b1a2c ("firmware: google: check if size is valid when decoding VPD data")
Cc: <stable@vger.kernel.org>
Cc: Hung-Te Lin <hungte@chromium.org>
Signed-off-by: Brian Norris <briannorris@chromium.org>
Reviewed-by: Stephen Boyd <swboyd@chromium.org>
Reviewed-by: Guenter Roeck <groeck@chromium.org>
Link: https://lore.kernel.org/r/20190930214522.240680-1-briannorris@chromium.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>