[RFC v2 0/2] rng: Provide a RNG based on the RISC-V Zkr ISA extension

[Heinrich Schuchardt]

The Zkr ISA extension (ratified Nov 2021) introduced the seed CSR. It
provides an interface to a physical entropy source.

A RNG driver based on the seed CSR is provided. It depends on
mseccfg.sseed being set in the SBI firmware.

If the seed CSR readable, is not determinable by S-mode without risking
an exception. For safe driver probing allow to resume via a longjmp
after an exception.

As the driver depends on mseccfg.sseed=1 we should wait with merging the
driver until a decision has been taken in the RISC-V PRS TG on prescribing
this.

Heinrich Schuchardt (2):
  riscv: allow resume after exception
  rng: Provide a RNG based on the RISC-V Zkr ISA extension

 arch/riscv/lib/interrupts.c |  13 ++++
 drivers/rng/Kconfig         |   8 +++
 drivers/rng/Makefile        |   1 +
 drivers/rng/riscv_zkr_rng.c | 116 ++++++++++++++++++++++++++++++++++++
 include/interrupt.h         |  22 +++++++
 5 files changed, 160 insertions(+)
 create mode 100644 drivers/rng/riscv_zkr_rng.c
 create mode 100644 include/interrupt.h

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2.40.1