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[v3,0/2] hwrng: Add Arm SMCCC TRNG based driver

Message ID 20210726175610.3311-1-andre.przywara@arm.com
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Series hwrng: Add Arm SMCCC TRNG based driver | expand

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Andre Przywara July 26, 2021, 5:56 p.m. UTC 
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 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 | 134 ++++++++++++++++++++++++
 drivers/firmware/smccc/smccc.c          |  17 +++
 4 files changed, 166 insertions(+)
 create mode 100644 drivers/char/hw_random/arm_smccc_trng.c