feat(nxp-drivers): add Linflex flush callback

Implement a flush callback for the Linflex UART driver to avoid cases
where the BL31 stage reinitializes the console while there is ongoing TX
initiated

feat(nxp-drivers): add Linflex flush callback

Implement a flush callback for the Linflex UART driver to avoid cases
where the BL31 stage reinitializes the console while there is ongoing TX
initiated by the BL2.

Change-Id: Ic49852f809198362de1f993474c7c45f1439dc98
Signed-off-by: Ghennadi Procopciuc <ghennadi.procopciuc@nxp.com>

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feat(nxp-drivers): add Linflex driver

This is a UART controller found on NXP automotive parts.
For instance: S32V, S32G and S32R.

Change-Id: Iff0dd0c379633ac0651e5db287537c87666b57d2
Signed-off-by:

feat(nxp-drivers): add Linflex driver

This is a UART controller found on NXP automotive parts.
For instance: S32V, S32G and S32R.

Change-Id: Iff0dd0c379633ac0651e5db287537c87666b57d2
Signed-off-by: Bogdan Hamciuc <bogdan.hamciuc@nxp.com>
Signed-off-by: Ghennadi Procopciuc <ghennadi.procopciuc@nxp.com>

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refactor(console): disable getc() by default

The ability to read a character from the console constitutes an attack
vector into TF-A, as it gives attackers a means to inject arbitrary
data into TF-A

refactor(console): disable getc() by default

The ability to read a character from the console constitutes an attack
vector into TF-A, as it gives attackers a means to inject arbitrary
data into TF-A. It is dangerous to keep that feature enabled if not
strictly necessary, especially in production firmware builds.

Thus, we need a way to disable this feature. Moreover, when it is
disabled, all related code should be eliminated from the firmware
binaries, such that no remnant/dead getc() code remains in memory,
which could otherwise be used as a gadget as part of a bigger security
attack.

This patch disables getc() feature by default. For legitimate getc()
use cases [1], it can be explicitly enabled by building TF-A with
ENABLE_CONSOLE_GETC=1.

The following changes are introduced when getc() is disabled:

- The multi-console framework no longer provides the console_getc()
function.

- If the console driver selected by the platform attempts to register
a getc() callback into the multi-console framework then TF-A will
now fail to build.

If registered through the assembly function finish_console_register():
- On AArch64, you'll get:
Error: undefined symbol CONSOLE_T_GETC used as an immediate value.
- On AArch32, you'll get:
Error: internal_relocation (type: OFFSET_IMM) not fixed up

If registered through the C function console_register(), this requires
populating a struct console with a getc field, which will trigger:
error: 'console_t' {aka 'struct console'} has no member named 'getc'

- All console drivers which previously registered a getc() callback
have been modified to do so only when ENABLE_CONSOLE_GETC=1.

[1] Example of such use cases would be:
- Firmware recovery: retrieving a golden BL2 image over the console in
order to repair a broken firmware on a bricked board.
- Factory CLI tool: Drive some soak tests through the console.

Discussed on TF-A mailing list here:
https://lists.trustedfirmware.org/archives/list/tf-a@lists.trustedfirmware.org/thread/YS7F6RCNTWBTEOBLAXIRTXWIOYINVRW7/

Change-Id: Icb412304cd23dbdd7662df7cf8992267b7975cc5
Signed-off-by: Sandrine Bailleux <sandrine.bailleux@arm.com>
Acked-by: Baruch Siach <baruch@tkos.co.il>

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