• David Brownell's avatar
    spi: add spi_master flag word · 70d6027f
    David Brownell authored
    
    
    Add a new spi_master.flags word listing constraints relevant to that
    controller.  Define the first constraint bit: a half duplex restriction.
    Include that constraint in the OMAP1 MicroWire controller driver.
    
    Have the mmc_spi host be the first customer of this flag.  Its coding
    relies heavily on full duplex transfers, so it must fail when the
    underlying controller driver won't perform them.
    
    (The spi_write_then_read routine could use it too: use the
    temporarily-withdrawn full-duplex speedup unless this flag is set, in
    which case the existing code applies.  Similarly, any spi_master
    implementing only SPI_3WIRE should set the flag.)
    Signed-off-by: default avatarDavid Brownell <dbrownell@users.sourceforge.net>
    Cc: Marek Szyprowski <m.szyprowski@samsung.com>
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    70d6027f
mmc_spi.c 42 KB