treewide, serdev: change receive_buf() return type to size_t

receive_buf() is called from ttyport_receive_buf() that expects values
">= 0" from serdev_controller_receive_buf(), change its return type from
ssize_t to size_t.

The need for this clean-up was noticed while fixing a warning, see
commit 94d053942544 ("Bluetooth: btnxpuart: fix recv_buf() return value").
Changing the callback prototype to return an unsigned seems the best way
to document the API and ensure that is properly used.

GNSS drivers implementation of serdev receive_buf() callback return
directly the return value of gnss_insert_raw(). gnss_insert_raw()
returns a signed int, however this is not an issue since the value
returned is always positive, because of the kfifo_in() implementation.
gnss_insert_raw() could be changed to return also an unsigned, however
this is not implemented here as request by the GNSS maintainer Johan
Hovold.

Suggested-by: Jiri Slaby <[email protected]>
Link: https://lore.kernel.org/all/[email protected]/
Signed-off-by: Francesco Dolcini <[email protected]>
Acked-by: Jonathan Cameron <[email protected]> #for-iio
Reviewed-by: Johan Hovold <[email protected]>
Reviewed-by: Rob Herring <[email protected]>
Reviewed-by: Alex Elder <[email protected]>
Acked-by: Maximilian Luz <[email protected]>  # for platform/surface
Acked-by: Lee Jones <[email protected]>
Acked-by: Ilpo Järvinen <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

0 files changed, 0 insertions, 0 deletions