[PATCH 1/3] dmaengine: add new dma API for max_segment_number

[shawn.guo@linaro.org (Shawn Guo)]

Like dma_set(get)_max_seg_size for max_segment_size, the patch adds
max_segment_number into device_dma_parameters and creates the
corresponding dmaengine API dma_set(get)_max_seg_number for it.

Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
---
 include/linux/device.h      |    1 +
 include/linux/dma-mapping.h |   15 +++++++++++++++
 2 files changed, 16 insertions(+), 0 deletions(-)

diff --git a/include/linux/device.h b/include/linux/device.h
index c66111a..44cb2528 100644
--- a/include/linux/device.h
+++ b/include/linux/device.h
@@ -487,6 +487,7 @@ struct device_dma_parameters {
 	 * sg limitations.
 	 */
 	unsigned int max_segment_size;
+	unsigned int max_segment_number;
 	unsigned long segment_boundary_mask;
 };
 
diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h
index ba8319a..fd314f4 100644
--- a/include/linux/dma-mapping.h
+++ b/include/linux/dma-mapping.h
@@ -131,6 +131,21 @@ static inline unsigned int dma_set_max_seg_size(struct device *dev,
 		return -EIO;
 }
 
+static inline unsigned int dma_get_max_seg_number(struct device *dev)
+{
+	return dev->dma_parms ? dev->dma_parms->max_segment_number : 1;
+}
+
+static inline unsigned int dma_set_max_seg_number(struct device *dev,
+						  unsigned int number)
+{
+	if (dev->dma_parms) {
+		dev->dma_parms->max_segment_number = number;
+		return 0;
+	} else
+		return -EIO;
+}
+
 static inline unsigned long dma_get_seg_boundary(struct device *dev)
 {
 	return dev->dma_parms ?
-- 
1.7.4.1