New ConnectX firmware introduces FW command interface revision 2,
which requires that for each QP, a chunk of send queue entries (the
"headroom") is kept marked as invalid, so that the HCA doesn't get
confused if it prefetches entries that haven't been posted yet.  Add
code to the driver to do this, and also update the user ABI so that
userspace can request that the prefetcher be turned off for userspace
QPs (we just leave the prefetcher on for all kernel QPs).

Unfortunately, marking send queue entries this way is confuses older
firmware, so we change the driver to allow only FW command interface
revisions 2.  This means that users will have to update their firmware
to work with the new driver, but the firmware is changing quickly and
the old firmware has lots of other bugs anyway, so this shouldn't be too
big a deal.

Based on a patch from Jack Morgenstein <jackm@dev.mellanox.co.il>.
Signed-off-by: NRoland Dreier <rolandd@cisco.com>

HCA firmware with incompatible changes to the FW commmand interface is
coming soon.  Add a check of the interface revision during
initialization and bail out if the firmware advertises a revision that
the driver doesn't know about.  This will avoid strange failures later
if the driver goes on using the wrong interface revision. 
Signed-off-by: NRoland Dreier <rolandd@cisco.com>

s/signifant/significant/
Signed-off-by: NRoland Dreier <rolandd@cisco.com>

Don't overrun fname[] array when decoding device flags.

This was spotted by the Coverity checker (CID 1642).
Signed-off-by: NRoland Dreier <rolandd@cisco.com>

Add an InfiniBand driver for Mellanox ConnectX adapters.  Because
these adapters can also be used as ethernet NICs and Fibre Channel 
HBAs, the driver is split into two modules: 
 
  mlx4_core: Handles low-level things like device initialization and 
    processing firmware commands.  Also controls resource allocation 
    so that the InfiniBand, ethernet and FC functions can share a 
    device without stepping on each other. 
 
  mlx4_ib: Handles InfiniBand-specific things; plugs into the 
    InfiniBand midlayer. 
Signed-off-by: NRoland Dreier <rolandd@cisco.com>