On Mon, Mar 18, 2019 at 11:05:58AM +0100, Benjamin Gaignard wrote:

Bus domains controllers allow to divided system on chip into multiple domains
that can be used to select by who hardware blocks could be accessed.
A domain could be a cluster of CPUs (or coprocessors), a range of addresses or
a group of hardware blocks.

Framework architecture is inspirated by pinctrl framework:
- a default configuration could be applied before bind the driver
- configurations could be apllied dynamically by drivers
- device node provides the bus domains configurations

An example of bus domains controller is STM32 ETZPC hardware block
which got 3 domains:
- secure: hardware blocks are only accessible by software running on trust
  zone.
- non-secure: hardware blocks are accessible by non-secure software (i.e.
  linux kernel).
- coprocessor: hardware blocks are only accessible by the corpocessor.
Up to 94 hardware blocks of the soc could be managed by ETZPC and
assigned to one of the three domains.

You fail to explain why do we need this in non-secure Linux ?
You need to have solid reasons as why this can't be done in secure
firmware. And yes I mean even on arm32. On platforms with such hardware
capabilities you will need some secure firmware to be running and these
things can be done there. I don't want this enabled for ARM64 at all,
firmware *has to deal* with this.

--
Regards,
Sudeep

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