X-Git-Url: https://git.karo-electronics.de/?a=blobdiff_plain;f=sound%2Fcore%2Fsgbuf.c;h=0a418503ec412c61e22da5ac31ddac96e6e436a4;hb=7455c7f4ac0e99e6c2af6b5387616c985814ee89;hp=d0f00356fc115a32db23bc8475f08a6aad178c47;hpb=1c4cf1d5845b59cdcbfad8e67272cf5b219ab062;p=karo-tx-linux.git

diff --git a/sound/core/sgbuf.c b/sound/core/sgbuf.c
index d0f00356fc11..0a418503ec41 100644
--- a/sound/core/sgbuf.c
+++ b/sound/core/sgbuf.c
@@ -22,6 +22,7 @@
 #include <linux/slab.h>
 #include <linux/mm.h>
 #include <linux/vmalloc.h>
+#include <linux/export.h>
 #include <sound/memalloc.h>
 
 
@@ -136,3 +137,29 @@ void *snd_malloc_sgbuf_pages(struct device *device,
 	snd_free_sgbuf_pages(dmab); /* free the table */
 	return NULL;
 }
+
+/*
+ * compute the max chunk size with continuous pages on sg-buffer
+ */
+unsigned int snd_sgbuf_get_chunk_size(struct snd_dma_buffer *dmab,
+				      unsigned int ofs, unsigned int size)
+{
+	struct snd_sg_buf *sg = dmab->private_data;
+	unsigned int start, end, pg;
+
+	start = ofs >> PAGE_SHIFT;
+	end = (ofs + size - 1) >> PAGE_SHIFT;
+	/* check page continuity */
+	pg = sg->table[start].addr >> PAGE_SHIFT;
+	for (;;) {
+		start++;
+		if (start > end)
+			break;
+		pg++;
+		if ((sg->table[start].addr >> PAGE_SHIFT) != pg)
+			return (start << PAGE_SHIFT) - ofs;
+	}
+	/* ok, all on continuous pages */
+	return size;
+}
+EXPORT_SYMBOL(snd_sgbuf_get_chunk_size);