serdev: document driver callbacks
Amend the driver-callback kerneldoc with calling context and expected
return values.
Note that this is based on the requirements and characteristics of the
tty-port controller implementation which receives data in workqueue
context and whose write_wakeup callback must not sleep.
Also note that while the receive_buf callback returns an integer, the
returned value is still expected to be non-negative (and no greater than
the buffer-size argument).
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/include/linux/serdev.h b/include/linux/serdev.h
index 9929063..d7a9713 100644
--- a/include/linux/serdev.h
+++ b/include/linux/serdev.h
@@ -27,8 +27,10 @@
/**
* struct serdev_device_ops - Callback operations for a serdev device
- * @receive_buf: Function called with data received from device.
- * @write_wakeup: Function called when ready to transmit more data.
+ * @receive_buf: Function called with data received from device;
+ * returns number of bytes accepted; may sleep.
+ * @write_wakeup: Function called when ready to transmit more data; must
+ * not sleep.
*/
struct serdev_device_ops {
int (*receive_buf)(struct serdev_device *, const unsigned char *, size_t);