Add 64 bit support to vchiq:
* update fields to the appropriate fixed bit-size variants
(everywhere [cf. e.g., ref:sizes and ref:sizes2])
* refer to event semaphores (that go into the very 32 bit VC) by
offset instead of pointers [ref:sems]
* dsb() is dsb(sy) in arm64 (vchiq_{core.c,core.h,kmod.c}) [ref:dsb]
* comment out some unneeded code in parse_rx_slots around
VCHIQ_MSG_BULK_RX (cf. [ref:deadcode])
* adapt remote_event_signal to arm64 caching behaviours (vchiq_kmod.c)
* refactor synchronization around remote_event_signal, forcing a
wmb to be on the safe side; thereby make it look more like what linux
does [ref:sync] (vchiq_{core,kmod}.c); and make a comment in
vchiq_core.c true (wasn't before)
* add a few more syncs to be on the safe side (vchiq_2835_arm.c)
* use arm64 dcache invalidation mechanisms (vchiq_2835_arm.c)
* explicitly invalidate pages on arm64 post bulk-read (vchiq_2835_arm.c)
* support bulk transfers on rpi-4 (aka "long address space"
transfers), by hard-coding their vc offset (0) and different
bit-shift [ref:longbulk] (vchiq_2835_arm.c)
* refactor a loop-of-constant-test (vchiq_2835_arm.c)
* use the correct (hard-coded) cache-line size on arm64
* rework the handling of chipset "features" to account for the
extra behaviours with 64 bit chipsets. (vchiq_kmod.c)
* add sysctl-s (log, arm_log) to control debug (vchiq_kmod.c)
* add example kernel config (GENERIC-VCHIQ)
Fixes:
* Rework error handling in create_pagelist, avoiding a potential
panic when freeing memory that had been dmamem_alloc, a potential
null dereference, and a leak when having problems pinning pages
(vchiq_2835_arm.c)
* fix a confusion about the behaviour cv_wait_sig that lead to
uninterruptible looping (vchiq_bsd.c)
* implement detection of fatal signals (vchiq_bsd.c)
* fix a confusion with the name of a variable introduced by
#a0b8746 that could lead to a panic when closing the cdev file
(vchiq_arm.c)
* release user connection when destructing cdevpriv and avoid
user processes sharing connection data, which lead to stalls
and data corruption. (vchiq_arm.c)
Update bcm2835_audio to work on 64bit systems:
* update VC audio fields (vc_vchi_audioserv_defs.h, bcm2835_audio.c)
* repurpose the hitherto unused `callback` field to help push a 64 bit
pointer in (bcm2835_audio.c)
* increase (hopefully) the robustness of the code that shifts data to
VC (bcm2835_audio.c)
* add a sysctl to control the amount of debugging info output by
bcm2835_audio.c
Tested on zero, zero2 and 4+ with ping, functional, bulk
and control vchiq_test-s, and omxplayer
[ref:dsb]: https://github.com/raspberrypi/linux/commit/35b7ebda57affcfd3616d39d5a727a4495b31123
[ref:sems]: https://github.com/raspberrypi/linux/commit/24a4262afb10907fce3cdbc3ae336fcf4cdaece5
[ref:sizes]: https://github.com/raspberrypi/linux/commit/e64568b8ea6c04e747e432c17ce2452652075216
[ref:sizes2]: https://github.com/raspberrypi/linux/commit/f9bee6dd24addfa00c2c8d50c25b73efbfbb28ba
[ref:deadcode]: https://github.com/raspberrypi/linux/commit/14f4d72fb799a9b3170a45ab80d4a3ddad541960
[ref:sync]: https://github.com/raspberrypi/linux/commit/51c071265079319583e4c6e8c61e09660300d0bf
[ref:longbulk]: https://github.com/raspberrypi/linux/commit/37f6f19a83722c9b866cecb5e455b2e16e5bbc6b