2018-02-27 18:11 GMT+01:00 Mark Rutland [off-list ref]:

On Tue, Feb 27, 2018 at 03:09:23PM +0100, Benjamin Gaignard wrote:

quoted

On early boot stages STM32MP1 platform is able to dedicate some hardware blocks
to a secure OS running in TrustZone.
We need to avoid using those hardware blocks on non-secure context (i.e. kernel)
because read/write access will all be discarded.

Extended TrustZone Protection driver register itself as listener of
BUS_NOTIFY_BIND_DRIVER and check, given the device address, if the hardware block
could be used in a Linux context. If not it returns NOTIFY_BAD to driver core
to stop driver probing.

Huh?

If these devices are not usable from the non-secure side, why are they
not removed form the DT (or marked disabled)?

In other cases, where resources are carved out for the secure side (e.g.
DRAM carveouts), that's how we handle things.

That true you can parse and disable a device a boot time but if DT doesn't
exactly reflect etzpc status bits we will in trouble when try to get access to
the device.
Changing the DT is a software protection while etzpc is an hardware protection
so we need to check it anyway.

Benjamin

Mark.

quoted

NOTE: patches 2 and 3 should be applied only on
git://git.kernel.org/pub/scm/linux/kernel/git/atorgue/stm32.git stm32-next
but until this patch: https://lkml.org/lkml/2018/2/26/386
find it way to mailine KBuild will complain about them.

Benjamin Gaignard (3):
  driver core: check notifier_call_chain return value
  dt-bindings: stm32: Add bindings for Extended TrustZone Protection
  ARM: mach-stm32: Add Extended TrustZone Protection driver

 .../bindings/arm/stm32/st,stm32mp1-etzpc.txt       |  13 ++
 arch/arm/mach-stm32/Kconfig                        |   7 +
 arch/arm/mach-stm32/Makefile                       |   1 +
 arch/arm/mach-stm32/stm32-etzpc.c                  | 252 +++++++++++++++++++++
 drivers/base/dd.c                                  |   9 +-
 5 files changed, 279 insertions(+), 3 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/arm/stm32/st,stm32mp1-etzpc.txt
 create mode 100644 arch/arm/mach-stm32/stm32-etzpc.c

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