mpi3mr: Adding FreeBSD OS Type to Fault/Reset Reason Code

[chandrakanth.patil_broadcom.com]

Summary

The driver is modified to add FreeBSD OS type in the upper nibble of the
fault/reset reason code for appropriate qualification of the reason code.

[mav]

sys/dev/mpi3mr/mpi3mr.c

1182–1185

As I see, ioc_num is 8 bit, so I worry that shifting it by 20 bits may result in undefined behavior. BTW why 20 if reset_reason is 16 bit?

[chandrakanth.patil_broadcom.com]

sys/dev/mpi3mr/mpi3mr.c

1182–1185

If the LHS is 8 bits variable or if the value of ioc_num itself is assigned after shifting its value by 20 bits, then there would be an
undefined value. Here, ioc_num variable is RHS so shifting its value by 20 bits and assigning it to scratchpad_0, which is 32 bits is
fine right (the compiler will take care of typecasting it internally so no need to typecast it explicitly). The firmware requirement specifies
that bits 28-31 are reserved for the OS type (supporting up to 16 OSes), bits 20-27 are reserved for ioc_num (8 bits), bits 0-15 are reserved
for reset_reason, and bits 16-19 may be reserved for future use.