From 35e60bfdbc14ce31bba55cc82144f8a2a82ede68 Mon Sep 17 00:00:00 2001 From: Peter Crosthwaite Date: Tue, 16 Apr 2013 10:27:16 +1000 Subject: stream: Add flow control API Add basic flow control to stream. A stream slave may return short, indicating that it is not capable of accepting any more data at the present time. Polling or a callback can be used via the can_push() function to determine when the slave can receive again. Signed-off-by: Peter Crosthwaite Signed-off-by: Edgar E. Iglesias --- include/hw/stream.h | 33 ++++++++++++++++++++++++++++++--- 1 file changed, 30 insertions(+), 3 deletions(-) (limited to 'include/hw/stream.h') diff --git a/include/hw/stream.h b/include/hw/stream.h index f6137d6e25..5bc47a93fe 100644 --- a/include/hw/stream.h +++ b/include/hw/stream.h @@ -18,14 +18,41 @@ typedef struct StreamSlave { Object Parent; } StreamSlave; +typedef void (*StreamCanPushNotifyFn)(void *opaque); + typedef struct StreamSlaveClass { InterfaceClass parent; - - void (*push)(StreamSlave *obj, unsigned char *buf, size_t len, + /** + * can push - determine if a stream slave is capable of accepting at least + * one byte of data. Returns false if cannot accept. If not implemented, the + * slave is assumed to always be capable of recieveing. + * @notify: Optional callback that the slave will call when the slave is + * capable of recieving again. Only called if false is returned. + * @notify_opaque: opaque data to pass to notify call. + */ + bool (*can_push)(StreamSlave *obj, StreamCanPushNotifyFn notify, + void *notify_opaque); + /** + * push - push data to a Stream slave. The number of bytes pushed is + * returned. If the slave short returns, the master must wait before trying + * again, the slave may continue to just return 0 waiting for the vm time to + * advance. The can_push() function can be used to trap the point in time + * where the slave is ready to recieve again, otherwise polling on a QEMU + * timer will work. + * @obj: Stream slave to push to + * @buf: Data to write + * @len: Maximum number of bytes to write + */ + size_t (*push)(StreamSlave *obj, unsigned char *buf, size_t len, uint32_t *app); } StreamSlaveClass; -void +size_t stream_push(StreamSlave *sink, uint8_t *buf, size_t len, uint32_t *app); +bool +stream_can_push(StreamSlave *sink, StreamCanPushNotifyFn notify, + void *notify_opaque); + + #endif /* STREAM_H */ -- cgit v1.2.3