(adding some more arm64 folks) On Fri, 29 Nov 2019 at 11:30, Neal Liu <neal.liu@xxxxxxxxxxxx> wrote: > > On Fri, 2019-11-29 at 18:02 +0800, Lars Persson wrote: > > Hi Neal, > > > > On Wed, Nov 27, 2019 at 3:23 PM Neal Liu <neal.liu@xxxxxxxxxxxx> wrote: > > > > > > For MediaTek SoCs on ARMv8 with TrustZone enabled, peripherals like > > > entropy sources is not accessible from normal world (linux) and > > > rather accessible from secure world (ATF/TEE) only. This driver aims > > > to provide a generic interface to ATF rng service. > > > > > > > I am working on several SoCs that also will need this kind of driver > > to get entropy from Arm trusted firmware. > > If you intend to make this a generic interface, please clean up the > > references to MediaTek and give it a more generic name. For example > > "Arm Trusted Firmware random number driver". > > > > It will also be helpful if the SMC call number is configurable. > > > > - Lars > > Yes, I'm trying to make this to a generic interface. I'll try to make > HW/platform related dependency to be configurable and let it more > generic. > Thanks for your suggestion. > I don't think it makes sense for each arm64 platform to expose an entropy source via SMC calls in a slightly different way, and model it as a h/w driver. Instead, we should try to standardize this, and perhaps expose it via the architectural helpers that already exist (get_random_seed_long() and friends), so they get plugged into the kernel random pool driver directly. Note that in addition to drivers based on vendor SMC calls, we already have a RNG h/w driver based on OP-TEE as well, where the driver attaches to a standardized trusted OS interface identified by a UUID, and which also gets invoked via SMC calls into secure firmware.
