CVSROOT: /cvs
Module name: src
Changes by: [email protected] 2021/05/27 22:36:33
Modified files:
sys/arch/arm64/conf: files.arm64
Added files:
sys/arch/arm64/dev: aplns.c
Log message:
start working on support for Apple NVME Storage as found in apple M1 devs
the Apple NVME Storage (aka ans) controller is almost but not quite
a vanilla nvme controller. one difference is that it doesnt attach
to a pci bus, so it needs this custom bus glue. this custom bus
glue also provides us with a nice way to provide a different set
of functions to handle other things that ans does differently to
vanilla nvme controllers.
this is different to how linux deals with ans. the linux support
fakes a pci controller for ans to attach to. i assumed that at some
point a vendor would include nvme in an soc directly and made it a
bus independent driver from day 1. turns out i was right, but i
would never have guessed that the vendor would be apple.
some of the other differences between vanilla nvme and ans are
around command submission and completion. ans nvme command submission
is done via an array of command slots where the host picks a slot
and then posts every slot number it fills in to a doorbell. this
is different to vanilla nvme controllers which use a ring, and post
the producer index in that ring to a doorbell. ans also includes
some weird iommu, the handling of which we wrap up into the command
submission and completion functions.
this code is not yet enabled because it is incomplete. i'm getting
what i've done in so people with actual hardware can start poking
it more seriously.
this implementation is based on information figured out by the guys
porting linux to apple hardware.
