PPC: dbdma: Introduce kick function

The DBDMA engine really is running all the time, waiting for input. However
we don't want to waste cycles constantly polling.

So introduce a kick function that data providers can call to notify the
DBDMA controller of new input.

Signed-off-by: Alexander Graf <agraf@suse.de>

hw/misc/macio/mac_dbdma.c

diff --git a/hw/misc/macio/mac_dbdma.c b/hw/misc/macio/mac_dbdma.c
index c55c75c..d1506ce 100644
--- a/hw/misc/macio/mac_dbdma.c
+++ b/hw/misc/macio/mac_dbdma.c
@@ -536,6 +536,11 @@
     DBDMA_run(s);
 }
 
+void DBDMA_kick(DBDMAState *dbdma)
+{
+    qemu_bh_schedule(dbdma_bh);
+}
+
 void DBDMA_register_channel(void *dbdma, int nchan, qemu_irq irq,
                             DBDMA_rw rw, DBDMA_flush flush,
                             void *opaque)

include/hw/ppc/mac_dbdma.h

diff --git a/include/hw/ppc/mac_dbdma.h b/include/hw/ppc/mac_dbdma.h
index 90be5d9..aaeab10 100644
--- a/include/hw/ppc/mac_dbdma.h
+++ b/include/hw/ppc/mac_dbdma.h
@@ -161,6 +161,7 @@
 void DBDMA_register_channel(void *dbdma, int nchan, qemu_irq irq,
                             DBDMA_rw rw, DBDMA_flush flush,
                             void *opaque);
+void DBDMA_kick(DBDMAState *dbdma);
 void* DBDMA_init (MemoryRegion **dbdma_mem);
 
 #endif