blk: Add bounce buffer support to read/write operations

Some devices have limited DMA capabilities and require that the
buffers passed to them fit specific properties. Add new optional
callback which can be used at driver level to indicate whether a
buffer alignment is suitable for the device DMA or not, and
trigger use of generic bounce buffer implementation to help use
of unsuitable buffers at the expense of performance degradation.

Signed-off-by: Marek Vasut <marek.vasut+renesas@mailbox.org>

1 files changed, 19 insertions, 0 deletions

diff --git a/include/blk.h b/include/blk.h
index 8986e953e5..b819f97c2f 100644
--- a/include/blk.h
+++ b/include/blk.h
@@ -7,6 +7,7 @@
 #ifndef BLK_H
 #define BLK_H
 
+#include <bouncebuf.h>
 #include <dm/uclass-id.h>
 #include <efi.h>
 
@@ -260,6 +261,24 @@ struct blk_ops {
 	 * @return 0 if OK, -ve on error
 	 */
 	int (*select_hwpart)(struct udevice *dev, int hwpart);
+
+#if IS_ENABLED(CONFIG_BOUNCE_BUFFER)
+	/**
+	 * buffer_aligned() - test memory alignment of block operation buffer
+	 *
+	 * Some devices have limited DMA capabilities and require that the
+	 * buffers passed to them fit specific properties. This optional
+	 * callback can be used to indicate whether a buffer alignment is
+	 * suitable for the device DMA or not, and trigger use of generic
+	 * bounce buffer implementation to help use of unsuitable buffers
+	 * at the expense of performance degradation.
+	 *
+	 * @dev:	Block device associated with the request
+	 * @state:	Bounce buffer state
+	 * @return 1 if OK, 0 if unaligned
+	 */
+	int (*buffer_aligned)(struct udevice *dev, struct bounce_buffer *state);
+#endif	/* CONFIG_BOUNCE_BUFFER */
 };
 
 /*