Le lun. 18 mars 2019 à 12:05, Benjamin Gaignard <benjamin.gaign...@linaro.org> a écrit : > > Le lun. 18 mars 2019 à 11:43, Sudeep Holla <sudeep.ho...@arm.com> a écrit : > > > > 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. > > We use ETZPC to define if hardware blocks can be used by Cortex A7 or Cortex > M4 > (both non-secure) on STM32MP1 SoC, this new framework allow to change hardware > block split at runtime. This could be done even on non-secure world > because their is > nothing critical to change hardware blocks users. > For example you can do "complex" tasks like display pipe configuration > on Cortex A7 > where linux is running and handover the control of this hardware block > to Cortex M4 to > offload drawing on framebuffer. >
Gentle ping to get more feedback on this series Benjamin > Benjamin > > > > > -- > > Regards, > > Sudeep