Intel has created RST and many laptops from vendors like Lenovo and Asus. It's a
mechanism for creating multiple boot devices under windows. It effectively hides
the nvme drive inside of the ahci controller. The details are supposed to be a
trade secret. However, there's a reverse engineered Linux driver, and this
implements similar operations to allow nvme drives to attach. The ahci driver
attaches nvme children that proxy the remapped resources to the child. nvme_ahci
is just like nvme_pci, except it doesn't do the PCI specific things. That's
moved into ahci where appropriate.
When the nvme drive is remapped, MSI-x interrupts aren't forwarded (the linux
driver doesn't know how to use this either). INTx interrupts are used
instead. This is suboptimal, but usually sufficient for the laptops these parts
are in.
This is based loosely on https://www.spinics.net/lists/linux-ide/msg53364.html
submitted, but not accepted by, Linux. It was written by Dan Williams. These
changes were written from scratch by Olivier Houchard.
Submitted by: cognet@ (Olivier Houchard)
Nvme drives can be attached in a number of different ways. Separate out the PCI
attachment so that we can have other attachment types, like ahci and various
types of NVMeoF.
Submitted by: cognet@
As part of this commit, add an nvme_strvis() function which borrows
heavily from cam_strvis(). This will allow stripping of
leading/trailing whitespace and also handle unprintable characters
in model/serial numbers. This function goes into a new nvme_util.c
file which is used by both the driver and nvmecontrol.
Sponsored by: Intel
Reviewed by: carl
MFC after: 3 days
