staging: vc04_services: Re-add dependency on HAS_DMA to BCM2835_VCHIQ

Thanks to stubs for the NO_DMA=y case, drivers that use the DMA API can
be compile-tested on systems that do not support DMA. Hence the
dependency of BCM2835_VCHIQ on HAS_DMA was dropped to increase compile
coverage.

Unfortunately compilers became smarter, leading to new failures.
E.g. for a CONFIG_SUN3=y allmodconfig kernel with gcc 9.4.0:

drivers/staging/vc04_services/interface/vchiq_arm/vchiq_2835_arm.c: In function ‘free_pagelist’:
arch/m68k/include/asm/string.h:72:25: warning: argument 2 null where non-null expected [-Wnonnull]
72 | #define memcpy(d, s, n) __builtin_memcpy(d, s, n)
| ^~~~~~~~~~~~~~~~~~~~~~~~~
drivers/staging/vc04_services/interface/vchiq_arm/vchiq_2835_arm.c:614:4: note: in expansion of macro ‘memcpy’
614 | memcpy((char *)kmap(pages[0]) +
| ^~~~~~
arch/m68k/include/asm/string.h:72:25: note: in a call to built-in function ‘__builtin_memcpy’
72 | #define memcpy(d, s, n) __builtin_memcpy(d, s, n)
| ^~~~~~~~~~~~~~~~~~~~~~~~~
drivers/staging/vc04_services/interface/vchiq_arm/vchiq_2835_arm.c:614:4: note: in expansion of macro ‘memcpy’
614 | memcpy((char *)kmap(pages[0]) +
| ^~~~~~

This happens because the compiler can trace back the source pointer to a
allocation by dma_alloc_attrs(), which always returns NULL if NO_DMA=y.

Avoid this reinstating the dependency of the BCM2835_VCHIQ symbol on
HAS_DMA, and by restricting the selection of BCM2835_VCHIQ.

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Link: https://lore.kernel.org/r/da55bd87eebf1a969dc8ccd807843319833f6c40.1650888813.git.geert@linux-m68k.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

staging: bcm2835-audio: fully describe config symbol

Explain SND_BCM2835 config option in more detail to fix checkpatch
warning:

WARNING: please write a help paragraph that fully describes the config
symbol
FILE: drivers/staging/vc04_services/bcm2835-audio/Kconfig:2

Signed-off-by: Adrien Thierry <athierry@redhat.com>
Link: https://lore.kernel.org/r/20220414181622.102049-2-athierry@redhat.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

staging: vc04: Fix Kconfig indentation

Adjust indentation from spaces to tab (+optional two spaces) as in
coding style with command like:
$ sed -e 's/^ /\t/' -i */Kconfig

Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
Link: https://lore.kernel.org/r/20191120133848.13250-1-krzk@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

staging: add missing SPDX lines to Kconfig files

There are a few remaining drivers/staging/*/Kconfig files that do not
have SPDX identifiers in them. Add the correct GPL-2.0 identifier to
them to make scanning tools happy.

Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

staging: bcm2835-audio: Enable compile test

Enable the compilation test for bcm2835-audio to gain more build coverage.

Signed-off-by: Stefan Wahren <stefan.wahren@i2se.com>
Reviewed-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
Reviewed-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

staging: bcm2835-audio: select BCM2835_VCHIQ rather then depending on it.

Change the audio's dependency on BCM2835_VCHIQ to a select
since audio support is typically more important to people
then base VCHIQ(which they may not even know what it's for).

Also, with a dependency the audio support would not be
visiable until VCHIQ is selected first, and that may
not be what most people would expect.

Signed-off-by: Michael Zoran <mzoran@crowfest.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

staging: bcm2835-audio: Update driver description

The audio driver description contains a reference to a card.
Since this is for built in audio, drop the card reference
from the description.

Signed-off-by: Michael Zoran <mzoran@crowfest.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

staging: bcm2835-audio: Move driver under vc04_services

The bcm2835-audio driver is part of v04_services, so it makes
sense for it to be located under vc04_services to make
configuration clearer.

Signed-off-by: Michael Zoran <mzoran@crowfest.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>