drivers: meson: sm: correct meson_sm_* API retval handling

1. Following the ARM SMC32 calling convention, the return value
from secure monitor is a 32-bit signed integer. This patch changes
the type of the return value of the function meson_sm_call().

2. Now, when meson_sm_call() returns a 32-bit signed integer, we need
to ensure that this value is not negative. It is important to check
that the return value is not negative in both the meson_sm_call_read()
and meson_sm_call_write() functions.

3. Add a comment explaining why it is necessary to check if the SMC
return value is equal to 0 in the function meson_sm_call_read().
It is not obvious when reading this code.

Signed-off-by: Alexey Romanov <avromanov@salutedevices.com>
Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>
Link: https://lore.kernel.org/r/20230830140850.17130-1-avromanov@salutedevices.com
Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>

firmware: meson_sm: Add secure power domain support

The Amlogic Meson A1/C1 Secure Monitor implements calls to control power
domain.

Signed-off-by: Jianxin Pan <jianxin.pan@amlogic.com>
Signed-off-by: Kevin Hilman <khilman@baylibre.com>
Link: https://lore.kernel.org/r/1579087831-94965-2-git-send-email-jianxin.pan@amlogic.com

firmware: meson_sm: Rework driver as a proper platform driver

The secure monitor driver is currently a frankenstein driver which is
registered as a platform driver but its functionality goes through a
global struct accessed by the consumer drivers using exported helper
functions.

Try to tidy up the driver moving the firmware struct into the driver
data and make the consumer drivers referencing the secure-monitor using
a new property in the DT.

Currently only the nvmem driver is using this API so we can fix it in
the same commit.

Reviewed-by: Jerome Brunet <jbrunet@baylibre.com>
Signed-off-by: Carlo Caione <ccaione@baylibre.com>
Signed-off-by: Kevin Hilman <khilman@baylibre.com>

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 446

Based on 1 normalized pattern(s):

this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license version 2 as
published by the free software foundation you should have received a
copy of the gnu general public license along with this program if
not see http www gnu org licenses

extracted by the scancode license scanner the SPDX license identifier

GPL-2.0-only

has been chosen to replace the boilerplate/reference in 30 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Allison Randal <allison@lohutok.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190531190115.962665879@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

firmware: meson_sm: Add serial number sysfs entry

The Amlogic Meson SoC Secure Monitor implements a call to retrieve an unique
SoC ID starting from the GX Family and all new families.

The serial number is simply exposed as a sysfs entry under the firmware
sysfs directory.

Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Signed-off-by: Kevin Hilman <khilman@baylibre.com>

firmware: meson-sm: Check for buffer output size

After the data is read by the secure monitor driver it is being copied
in the output buffer checking only the size of the bounce buffer but not
the size of the output buffer.

Fix this in the secure monitor driver slightly changing the API. Fix
also the efuse driver that it is the only driver using this API to not
break bisectability.

Signed-off-by: Carlo Caione <carlo@endlessm.com>
Acked-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org> # for nvmem
Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Kevin Hilman <khilman@baylibre.com>

firmware: Amlogic: Add secure monitor driver

Introduce a driver to provide calls into secure monitor mode.

In the Amlogic SoCs these calls are used for multiple reasons: access to
NVMEM, set USB boot, enable JTAG, etc...

Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Carlo Caione <carlo@endlessm.com>
[khilman: add in SZ_4K cleanup]
Signed-off-by: Kevin Hilman <khilman@baylibre.com>