• Mark A. Greer's avatar
    [PATCH] serial: MPSC driver · ab0ef3e9
    Mark A. Greer authored
    Patch for the Marvell MultiProtocol Serial Controller (MPSC).  This ctlr is
    on a series of host bridges (and other things) for PPC and MIPS processors.
    
    The ctlr operates similar to a typical network controller with send and
    receive rings.  Unfortunately there are many errata so you will see some
    "unusual" things in the code.  For example: a) An erratum prevents the
    reading of several registers on the ctlr (writing is okay).  To work around
    that, a local copy of what the registers are is kept and special macros are
    used to access those mirrored values.  b) Another erratum says that the
    MPSC cannot be used to access cache coherent memory (and many of the
    systems I use are cache coherent).  However, it seems to work okay as long
    as there are no snoop hits so there are macros in the code to manually
    manage the caches to prevent snoop hits.  Each macro checks a flag to see
    if the manual cache mgmt is necessary as not all versions have the erratum.
    
    The driver seems to work well but more testing is needed and it is lacking
    KGDB support.  I will get to both of those in time.
    Signed-off-by: default avatarMark A. Greer <mgreer@mvista.com>
    Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
    ab0ef3e9
mpsc.c 40.8 KB