[PATCH v5 6/9] dma-buf: heaps: restricted_heap: Add dma_ops

[Yong Wu <yong.wu@xxxxxxxxxxxx>]

Add the dma_ops for this restricted heap. For restricted buffer,
1) cache_ops/mmap are not allowed, thus return EPERM for them.
2) In map_dma_buf, use DMA_ATTR_SKIP_CPU_SYNC to skip cache sync since
   the buffer is protected.
This type buffers are marked by sg_dma_mark_restricted, the user could
check if this is a restricted buffer by sg_dma_is_restricted.

Signed-off-by: Yong Wu <yong.wu@xxxxxxxxxxxx>
---
 drivers/dma-buf/heaps/restricted_heap.c | 102 ++++++++++++++++++++++++
 drivers/dma-buf/heaps/restricted_heap.h |   2 +
 2 files changed, 104 insertions(+)

diff --git a/drivers/dma-buf/heaps/restricted_heap.c b/drivers/dma-buf/heaps/restricted_heap.c
index 8bb3c1876a69..4e45d46a6467 100644
--- a/drivers/dma-buf/heaps/restricted_heap.c
+++ b/drivers/dma-buf/heaps/restricted_heap.c
@@ -8,10 +8,16 @@
 #include <linux/dma-buf.h>
 #include <linux/dma-heap.h>
 #include <linux/err.h>
+#include <linux/scatterlist.h>
 #include <linux/slab.h>
 
 #include "restricted_heap.h"
 
+struct restricted_heap_attachment {
+	struct sg_table			*table;
+	struct device			*dev;
+};
+
 static int
 restricted_heap_memory_allocate(struct restricted_heap *rheap, struct restricted_buffer *buf)
 {
@@ -45,6 +51,101 @@ restricted_heap_memory_free(struct restricted_heap *rheap, struct restricted_buf
 	ops->free(rheap, buf);
 }
 
+static int restricted_heap_attach(struct dma_buf *dmabuf, struct dma_buf_attachment *attachment)
+{
+	struct restricted_buffer *restricted_buf = dmabuf->priv;
+	struct restricted_heap_attachment *a;
+	struct sg_table *table;
+
+	a = kzalloc(sizeof(*a), GFP_KERNEL);
+	if (!a)
+		return -ENOMEM;
+
+	table = sg_dup_table(&restricted_buf->sg_table);
+	if (!table) {
+		kfree(a);
+		return -ENOMEM;
+	}
+
+	sg_dma_mark_restricted(table->sgl);
+	a->table = table;
+	a->dev = attachment->dev;
+	attachment->priv = a;
+
+	return 0;
+}
+
+static void restricted_heap_detach(struct dma_buf *dmabuf, struct dma_buf_attachment *attachment)
+{
+	struct restricted_heap_attachment *a = attachment->priv;
+
+	sg_free_table(a->table);
+	kfree(a->table);
+	kfree(a);
+}
+
+static struct sg_table *
+restricted_heap_map_dma_buf(struct dma_buf_attachment *attachment,
+			    enum dma_data_direction direction)
+{
+	struct restricted_heap_attachment *a = attachment->priv;
+	struct sg_table *table = a->table;
+	int ret;
+
+	ret = dma_map_sgtable(attachment->dev, table, direction, DMA_ATTR_SKIP_CPU_SYNC);
+	if (ret)
+		return ERR_PTR(ret);
+	return table;
+}
+
+static void
+restricted_heap_unmap_dma_buf(struct dma_buf_attachment *attachment, struct sg_table *table,
+			      enum dma_data_direction direction)
+{
+	struct restricted_heap_attachment *a = attachment->priv;
+
+	WARN_ON(a->table != table);
+
+	dma_unmap_sgtable(attachment->dev, table, direction, DMA_ATTR_SKIP_CPU_SYNC);
+}
+
+static int
+restricted_heap_dma_buf_begin_cpu_access(struct dma_buf *dmabuf, enum dma_data_direction direction)
+{
+	return -EPERM;
+}
+
+static int
+restricted_heap_dma_buf_end_cpu_access(struct dma_buf *dmabuf, enum dma_data_direction direction)
+{
+	return -EPERM;
+}
+
+static int restricted_heap_dma_buf_mmap(struct dma_buf *dmabuf, struct vm_area_struct *vma)
+{
+	return -EPERM;
+}
+
+static void restricted_heap_free(struct dma_buf *dmabuf)
+{
+	struct restricted_buffer *restricted_buf = dmabuf->priv;
+	struct restricted_heap *rheap = dma_heap_get_drvdata(restricted_buf->heap);
+
+	restricted_heap_memory_free(rheap, restricted_buf);
+	kfree(restricted_buf);
+}
+
+static const struct dma_buf_ops restricted_heap_buf_ops = {
+	.attach		= restricted_heap_attach,
+	.detach		= restricted_heap_detach,
+	.map_dma_buf	= restricted_heap_map_dma_buf,
+	.unmap_dma_buf	= restricted_heap_unmap_dma_buf,
+	.begin_cpu_access = restricted_heap_dma_buf_begin_cpu_access,
+	.end_cpu_access	= restricted_heap_dma_buf_end_cpu_access,
+	.mmap		= restricted_heap_dma_buf_mmap,
+	.release	= restricted_heap_free,
+};
+
 static struct dma_buf *
 restricted_heap_allocate(struct dma_heap *heap, unsigned long size,
 			 unsigned long fd_flags, unsigned long heap_flags)
@@ -66,6 +167,7 @@ restricted_heap_allocate(struct dma_heap *heap, unsigned long size,
 	if (ret)
 		goto err_free_buf;
 	exp_info.exp_name = dma_heap_get_name(heap);
+	exp_info.ops = &restricted_heap_buf_ops;
 	exp_info.size = restricted_buf->size;
 	exp_info.flags = fd_flags;
 	exp_info.priv = restricted_buf;
diff --git a/drivers/dma-buf/heaps/restricted_heap.h b/drivers/dma-buf/heaps/restricted_heap.h
index 5783275d5714..6d9599a4a34e 100644
--- a/drivers/dma-buf/heaps/restricted_heap.h
+++ b/drivers/dma-buf/heaps/restricted_heap.h
@@ -11,6 +11,8 @@
 struct restricted_buffer {
 	struct dma_heap		*heap;
 	size_t			size;
+
+	struct sg_table		sg_table;
 };
 
 struct restricted_heap {
-- 
2.25.1