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[PATCH/RFC,116/390] dma-buf: add vmap interface

Message ID 1364525119-31791-117-git-send-email-horms+renesas@verge.net.au (mailing list archive)
State New, archived
Headers show

Commit Message

Simon Horman March 29, 2013, 2:40 a.m. UTC
From: Dave Airlie <airlied@redhat.com>

The main requirement I have for this interface is for scanning out
using the USB gpu devices. Since these devices have to read the
framebuffer on updates and linearly compress it, using kmaps
is a major overhead for every update.

v2: fix warn issues pointed out by Sylwester Nawrocki.

v3: fix compile !CONFIG_DMA_SHARED_BUFFER and add _GPL for now

Signed-off-by: Dave Airlie <airlied@redhat.com>
Reviewed-by: Rob Clark <rob.clark@linaro.org>
Signed-off-by: Sumit Semwal <sumit.semwal@linaro.org>
(cherry picked from commit 98f86c9e4ae3205e4c85c535691a5d36426360ee)

Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
---
 drivers/base/dma-buf.c  |   34 ++++++++++++++++++++++++++++++++++
 include/linux/dma-buf.h |   14 ++++++++++++++
 2 files changed, 48 insertions(+)
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Patch

diff --git a/drivers/base/dma-buf.c b/drivers/base/dma-buf.c
index 7cfb405..d43d802 100644
--- a/drivers/base/dma-buf.c
+++ b/drivers/base/dma-buf.c
@@ -468,3 +468,37 @@  int dma_buf_mmap(struct dma_buf *dmabuf, struct vm_area_struct *vma,
 	return dmabuf->ops->mmap(dmabuf, vma);
 }
 EXPORT_SYMBOL_GPL(dma_buf_mmap);
+
+/**
+ * dma_buf_vmap - Create virtual mapping for the buffer object into kernel address space. Same restrictions as for vmap and friends apply.
+ * @dma_buf:	[in]	buffer to vmap
+ *
+ * This call may fail due to lack of virtual mapping address space.
+ * These calls are optional in drivers. The intended use for them
+ * is for mapping objects linear in kernel space for high use objects.
+ * Please attempt to use kmap/kunmap before thinking about these interfaces.
+ */
+void *dma_buf_vmap(struct dma_buf *dmabuf)
+{
+	if (WARN_ON(!dmabuf))
+		return NULL;
+
+	if (dmabuf->ops->vmap)
+		return dmabuf->ops->vmap(dmabuf);
+	return NULL;
+}
+EXPORT_SYMBOL_GPL(dma_buf_vmap);
+
+/**
+ * dma_buf_vunmap - Unmap a vmap obtained by dma_buf_vmap.
+ * @dma_buf:	[in]	buffer to vmap
+ */
+void dma_buf_vunmap(struct dma_buf *dmabuf, void *vaddr)
+{
+	if (WARN_ON(!dmabuf))
+		return;
+
+	if (dmabuf->ops->vunmap)
+		dmabuf->ops->vunmap(dmabuf, vaddr);
+}
+EXPORT_SYMBOL_GPL(dma_buf_vunmap);
diff --git a/include/linux/dma-buf.h b/include/linux/dma-buf.h
index 1f78d15..a02b1ff 100644
--- a/include/linux/dma-buf.h
+++ b/include/linux/dma-buf.h
@@ -98,6 +98,9 @@  struct dma_buf_ops {
 	void (*kunmap)(struct dma_buf *, unsigned long, void *);
 
 	int (*mmap)(struct dma_buf *, struct vm_area_struct *vma);
+
+	void *(*vmap)(struct dma_buf *);
+	void (*vunmap)(struct dma_buf *, void *vaddr);
 };
 
 /**
@@ -176,6 +179,8 @@  void dma_buf_kunmap(struct dma_buf *, unsigned long, void *);
 
 int dma_buf_mmap(struct dma_buf *, struct vm_area_struct *,
 		 unsigned long);
+void *dma_buf_vmap(struct dma_buf *);
+void dma_buf_vunmap(struct dma_buf *, void *vaddr);
 #else
 
 static inline struct dma_buf_attachment *dma_buf_attach(struct dma_buf *dmabuf,
@@ -264,6 +269,15 @@  static inline int dma_buf_mmap(struct dma_buf *dmabuf,
 {
 	return -ENODEV;
 }
+
+static inline void *dma_buf_vmap(struct dma_buf *dmabuf)
+{
+	return NULL;
+}
+
+static inline void dma_buf_vunmap(struct dma_buf *dmabuf, void *vaddr)
+{
+}
 #endif /* CONFIG_DMA_SHARED_BUFFER */
 
 #endif /* __DMA_BUF_H__ */