The "Arm True Random Number Generator Firmware Interface"[1] provides an SMCCC based interface to a true hardware random number generator. So far we are using that in arch_get_random_seed(), but it might be useful to expose the entropy through the /dev/hwrng device as well. This allows to assess the quality of the implementation, by using "rngtest" from the rng-tools package, for example. Patch 1 creates a platform device, triggered by the previous discovery of the SMCCC TRNG service. Patch 2 implements a hw_random platform driver, which is instantiated through this said platform device. The driver can be loaded as module, or built into the kernel. [1] https://developer.arm.com/documentation/den0098/latest/ Changelog v3 ... v4: - drop pointless driver loading message - drop unneeded init() routine Changelog v2 ... v3: - split platform device and driver Changelog v1 ... v2: - fix building as a module - de-register device upon exit - mention module name in Kconfig Andre Przywara (2): firmware: smccc: Register smccc_trng platform device hwrng: Add Arm SMCCC TRNG based driver drivers/char/hw_random/Kconfig | 14 +++ drivers/char/hw_random/Makefile | 1 + drivers/char/hw_random/arm_smccc_trng.c | 123 ++++++++++++++++++++++++ drivers/firmware/smccc/smccc.c | 17 ++++ 4 files changed, 155 insertions(+) create mode 100644 drivers/char/hw_random/arm_smccc_trng.c -- 2.17.6
