ioat(4): Add ioat_get_max_io_size() KPI

Consumers need to know the permitted IO size to send maximally sized
chunks to the hardware.

Sponsored by:	EMC / Isilon Storage Division

2 files changed, 10 insertions, 0 deletions

diff --git a/sys/dev/ioat/ioat.c b/sys/dev/ioat/ioat.c
index 4b6d7df..c93d1b5 100644
--- a/sys/dev/ioat/ioat.c
+++ b/sys/dev/ioat/ioat.c
@@ -744,6 +744,15 @@ ioat_get_hwversion(bus_dmaengine_t dmaengine)
 	return (ioat->version);
 }
 
+size_t
+ioat_get_max_io_size(bus_dmaengine_t dmaengine)
+{
+	struct ioat_softc *ioat;
+
+	ioat = to_ioat_softc(dmaengine);
+	return (ioat->max_xfer_size);
+}
+
 int
 ioat_set_interrupt_coalesce(bus_dmaengine_t dmaengine, uint16_t delay)
 {
diff --git a/sys/dev/ioat/ioat.h b/sys/dev/ioat/ioat.h
index e8f47ae..f5d5fad 100644
--- a/sys/dev/ioat/ioat.h
+++ b/sys/dev/ioat/ioat.h
@@ -70,6 +70,7 @@ void ioat_put_dmaengine(bus_dmaengine_t dmaengine);
 
 /* Check the DMA engine's HW version */
 int ioat_get_hwversion(bus_dmaengine_t dmaengine);
+size_t ioat_get_max_io_size(bus_dmaengine_t dmaengine);
 
 /*
  * Set interrupt coalescing on a DMA channel.