The hardware does not support keeping CS asserted after sending one
FIFO buffer worth of data, so reject transfers requiring CS being kept
asserted, either between transers or for a certain time after it,
or exceeding the FIFO size.
Signed-off-by: NJonas Gorski <jogo@openwrt.org>
Acked-by: NFlorian Fainelli <florian@openwrt.org>
Signed-off-by: NGrant Likely <grant.likely@secretlab.ca>