dma-buf: add vmap interface

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>

diff --git a/drivers/base/dma-buf.c b/drivers/base/dma-buf.c
index 7cfb405b1ad5d7d5787a50ebe6f85fffd768820b..d43d80256fdae130f2216527e805fef8a8ead812 100644 (file)
--- 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 1f78d1594cc7a2400bf7f383439c88dcdd1e53c5..a02b1ff6488ef8c672c5f1dff17cf0a15fdc49d6 100644 (file)
--- 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__ */