soc: apple: rtkit: Port to the internal mailbox driver

Now that we have a mailbox driver in drivers/soc/apple, port the RTKit
code to it. This mostly just entails replacing calls through the mailbox
subsystem with direct calls into the driver.

Acked-by: Eric Curtin <ecurtin@redhat.com>
Acked-by: Neal Gompa <neal@gompa.dev>
Acked-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
Signed-off-by: Hector Martin <marcan@marcan.st>

soc: apple: rtkit: Get rid of apple_rtkit_send_message_wait

It is fundamentally broken and has no users. Just remove it.

Acked-by: Eric Curtin <ecurtin@redhat.com>
Acked-by: Neal Gompa <neal@gompa.dev>
Acked-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
Signed-off-by: Hector Martin <marcan@marcan.st>

soc: apple: rtkit: Crop syslog messages

Crop trailing whitespace, null, and newline characters in syslog
messages received from coprocessors. Notably DCP sends its messages
including a trailing newline, so prior to this change we would end up
cluttering the kernel log by repeated newlines at the end of messages.

Signed-off-by: Martin Povišer <povik+lin@cutebit.org>
Reviewed-by: Hector Martin <marcan@marcan.st>
Signed-off-by: Hector Martin <marcan@marcan.st>

soc: apple: rtkit: Fix buffer address field width

The buffer address field is missing two bits. This matters for the GPU,
which uses upper-half 64-bit addresses on the ASC and those get sign
extended from the mailbox message field, so the right number of high
bits need to be set.

Signed-off-by: Asahi Lina <lina@asahilina.net>
Reviewed-by: Sven Peter <sven@svenpeter.dev>
Signed-off-by: Hector Martin <marcan@marcan.st>

soc: apple: rtkit: Export non-devm init/free functions

While we normally encourage devm usage by drivers, some consumers (and
in particular the upcoming Rust abstractions) might want to manually
manage memory. Export the raw functions to make this possible.

Signed-off-by: Asahi Lina <lina@asahilina.net>
Reviewed-by: Sven Peter <sven@svenpeter.dev>
Reviewed-by: Eric Curtin <ecurtin@redhat.com>
Signed-off-by: Hector Martin <marcan@marcan.st>

soc: apple: rtkit: Add apple_rtkit_idle() function

This is yet another low power mode, used by DCP.

Reviewed-by: Eric Curtin <ecurtin@redhat.com>
Reviewed-by: Sven Peter <sven@svenpeter.dev>
Signed-off-by: Hector Martin <marcan@marcan.st>

soc: apple: rtkit: Stop casting function pointer signatures

Fixes: 9bd1d9a0d8bb ("soc: apple: Add RTKit IPC library")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Sven Peter <sven@svenpeter.dev>
Signed-off-by: Hector Martin <marcan@marcan.st>

soc: apple: rtkit: Add apple_rtkit_poll

This allows a client to receive messages in atomic context, by polling.

Signed-off-by: Hector Martin <marcan@marcan.st>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Reviewed-by: Sven Peter <sven@svenpeter.dev>
Reviewed-by: Eric Curtin <ecurtin@redhat.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

soc: apple: Add RTKit IPC library

Apple SoCs such as the M1 come with multiple embedded co-processors
running proprietary firmware. Communication with those is established
over a simple mailbox using the RTKit IPC protocol.

This cannot be implemented inside the mailbox subsystem since on top
of communication over channels we also need support for starting,
hibernating and resetting these co-processors. We also need to
handle shared memory allocations differently depending on the
co-processor and don't want to split that across multiple drivers.

Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Sven Peter <sven@svenpeter.dev>