[RFC PATCH v5 0/2] Add file-backed and write-once features to OTP

[Green Wan]

Based RFC v4 to fix:
 - Change the patch order
 - Add write operation to update pdin to fuse[] bit by bit 
 - Fix wrong protection for offset 0x0~0x38
 - Add SIFIVE_U_OTP_PWE_EN definition
 - Refine access macro for fuse[] and fuse_wo[]

Summary of Patches 
 - First patch is to add write opertion to update pdin data to fuse[] bit
   by bit. Add 'write-once' feature to block second write to same bit of
   the OTP memory.

 - Second patch is to add file-backed implementation to allow users to use
   '-drive' to assign an OTP raw image file. OTP image file must be bigger
   than 16K.

       For example, '-drive if=none,format=raw,file=otp.img'

Testing
 - Tested on sifive_u for both qemu and u-boot.

Green Wan (2):
  hw/riscv: sifive_u: Add write operation and write-once protection
  hw/riscv: sifive_u: Add backend drive support

 hw/riscv/sifive_u_otp.c         | 80 ++++++++++++++++++++++++++++++++-
 include/hw/riscv/sifive_u_otp.h |  5 +++
 2 files changed, 84 insertions(+), 1 deletion(-)

-- 
2.17.1