[1/8] lib/scatterlist: add sg_set_dma_addr() helper

Commit Message

Christian König March 25, 2018, 10:59 a.m. UTC

Use this function to set an sg entry to point to device resources mapped
using dma_map_resource(). The page pointer is set to NULL and only the DMA
address, length and offset values are valid.

Signed-off-by: Christian König <[e-mail]>
---
 include/linux/scatterlist.h | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

Comments

Christoph Hellwig March 28, 2018, 12:37 p.m. UTC | #1

On Sun, Mar 25, 2018 at 12:59:53PM +0200, Christian König wrote:
> Use this function to set an sg entry to point to device resources mapped
> using dma_map_resource(). The page pointer is set to NULL and only the DMA
> address, length and offset values are valid.

NAK.  Please provide a higher level primitive.

Btw, you series seems to miss a cover letter.

Patch

diff --git a/include/linux/scatterlist.h b/include/linux/scatterlist.h
index 22b2131bcdcd..f944ee4e482c 100644
--- a/include/linux/scatterlist.h
+++ b/include/linux/scatterlist.h
@@ -149,6 +149,29 @@  static inline void sg_set_buf(struct scatterlist *sg, const void *buf,
 	sg_set_page(sg, virt_to_page(buf), buflen, offset_in_page(buf));
 }
 
+/**
+ * sg_set_dma_addr - Set sg entry to point at specified dma address
+ * @sg:		 SG entry
+ * @address:	 DMA address to set
+ * @len:	 Length of data
+ * @offset:	 Offset into page
+ *
+ * Description:
+ *   Use this function to set an sg entry to point to device resources mapped
+ *   using dma_map_resource(). The page pointer is set to NULL and only the DMA
+ *   address, length and offset values are valid.
+ *
+ **/
+static inline void sg_set_dma_addr(struct scatterlist *sg, dma_addr_t address,
+				   unsigned int len, unsigned int offset)
+{
+	sg_set_page(sg, NULL, len, offset);
+	sg->dma_address = address;
+#ifdef CONFIG_NEED_SG_DMA_LENGTH
+	sg->dma_length = len;
+#endif
+}
+
 /*
  * Loop over each sg element, following the pointer to a new list if necessary
  */