[RFCv3][PATCH 5/5] staging: ion: Add support for syncing with DMA_BUF_IOCTL_SYNC

[Laura Abbott]

dma_buf added support for a userspace syncing ioctl. It is implemented
by calling dma_buf_begin_cpu_access and dma_buf_end_cpu_access. Ion
currently lacks cache operations on this code path. Add them for
compatibility with the dma_buf ioctl.

Signed-off-by: Laura Abbott <labb...@redhat.com>
---
 drivers/staging/android/ion/ion.c | 31 +++++++++++++++++++++++++++++++
 1 file changed, 31 insertions(+)

diff --git a/drivers/staging/android/ion/ion.c 
b/drivers/staging/android/ion/ion.c
index c2125de..1ad8e8a 100644
--- a/drivers/staging/android/ion/ion.c
+++ b/drivers/staging/android/ion/ion.c
@@ -969,6 +969,24 @@ static void ion_dma_buf_kunmap(struct dma_buf *dmabuf, 
unsigned long offset,
 {
 }
 
+static void ion_clean_buffer(struct ion_buffer *buffer)
+{
+       struct scatterlist *sg;
+       int i;
+
+       for_each_sg(buffer->sg_table->sgl, sg, buffer->sg_table->orig_nents, i)
+               kernel_force_cache_clean(sg_page(sg), sg->length);
+}
+
+static void ion_invalidate_buffer(struct ion_buffer *buffer)
+{
+       struct scatterlist *sg;
+       int i;
+
+       for_each_sg(buffer->sg_table->sgl, sg, buffer->sg_table->orig_nents, i)
+               kernel_force_cache_invalidate(sg_page(sg), sg->length);
+}
+
 static int ion_dma_buf_begin_cpu_access(struct dma_buf *dmabuf,
                                        enum dma_data_direction direction)
 {
@@ -984,6 +1002,11 @@ static int ion_dma_buf_begin_cpu_access(struct dma_buf 
*dmabuf,
        mutex_lock(&buffer->lock);
        vaddr = ion_buffer_kmap_get(buffer);
        mutex_unlock(&buffer->lock);
+
+       if (direction != DMA_TO_DEVICE) {
+               ion_invalidate_buffer(buffer);
+       }
+
        return PTR_ERR_OR_ZERO(vaddr);
 }
 
@@ -996,6 +1019,12 @@ static int ion_dma_buf_end_cpu_access(struct dma_buf 
*dmabuf,
        ion_buffer_kmap_put(buffer);
        mutex_unlock(&buffer->lock);
 
+       if (direction == DMA_FROM_DEVICE) {
+               ion_invalidate_buffer(buffer);
+       } else {
+               ion_clean_buffer(buffer);
+       }
+
        return 0;
 }
 
@@ -1126,6 +1155,8 @@ int ion_sync_for_device(struct ion_client *client, int fd)
        struct dma_buf *dmabuf;
        struct ion_buffer *buffer;
 
+       WARN_ONCE(1, "This API is deprecated in favor of the dma_buf ioctl\n");
+
        dmabuf = dma_buf_get(fd);
        if (IS_ERR(dmabuf))
                return PTR_ERR(dmabuf);
-- 
2.7.4