1 files changed, 176 insertions, 0 deletions

diff --git a/include/linux/dma-buf.h b/include/linux/dma-buf.h
new file mode 100644
index 000000000000..f8ac076afa52
--- /dev/null
+++ b/include/linux/dma-buf.h
@@ -0,0 +1,176 @@
+/*
+ * Header file for dma buffer sharing framework.
+ *
+ * Copyright(C) 2011 Linaro Limited. All rights reserved.
+ * Author: Sumit Semwal <sumit.semwal@ti.com>
+ *
+ * Many thanks to linaro-mm-sig list, and specially
+ * Arnd Bergmann <arnd@arndb.de>, Rob Clark <rob@ti.com> and
+ * Daniel Vetter <daniel@ffwll.ch> for their support in creation and
+ * refining of this idea.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published by
+ * the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+#ifndef __DMA_BUF_H__
+#define __DMA_BUF_H__
+
+#include <linux/file.h>
+#include <linux/err.h>
+#include <linux/device.h>
+#include <linux/scatterlist.h>
+#include <linux/list.h>
+#include <linux/dma-mapping.h>
+
+struct dma_buf;
+struct dma_buf_attachment;
+
+/**
+ * struct dma_buf_ops - operations possible on struct dma_buf
+ * @attach: [optional] allows different devices to 'attach' themselves to the
+ *          given buffer. It might return -EBUSY to signal that backing storage
+ *          is already allocated and incompatible with the requirements
+ *          of requesting device.
+ * @detach: [optional] detach a given device from this buffer.
+ * @map_dma_buf: returns list of scatter pages allocated, increases usecount
+ *               of the buffer. Requires atleast one attach to be called
+ *               before. Returned sg list should already be mapped into
+ *               _device_ address space. This call may sleep. May also return
+ *               -EINTR. Should return -EINVAL if attach hasn't been called yet.
+ * @unmap_dma_buf: decreases usecount of buffer, might deallocate scatter
+ *                 pages.
+ * @release: release this buffer; to be called after the last dma_buf_put.
+ */
+struct dma_buf_ops {
+        int (*attach)(struct dma_buf *, struct device *,
+                        struct dma_buf_attachment *);
+
+        void (*detach)(struct dma_buf *, struct dma_buf_attachment *);
+
+        /* For {map,unmap}_dma_buf below, any specific buffer attributes
+         * required should get added to device_dma_parameters accessible
+         * via dev->dma_params.
+         */
+        struct sg_table * (*map_dma_buf)(struct dma_buf_attachment *,
+                                                enum dma_data_direction);
+        void (*unmap_dma_buf)(struct dma_buf_attachment *,
+                                                struct sg_table *);
+        /* TODO: Add try_map_dma_buf version, to return immed with -EBUSY
+         * if the call would block.
+         */
+
+        /* after final dma_buf_put() */
+        void (*release)(struct dma_buf *);
+
+};
+
+/**
+ * struct dma_buf - shared buffer object
+ * @size: size of the buffer
+ * @file: file pointer used for sharing buffers across, and for refcounting.
+ * @attachments: list of dma_buf_attachment that denotes all devices attached.
+ * @ops: dma_buf_ops associated with this buffer object.
+ * @priv: exporter specific private data for this buffer object.
+ */
+struct dma_buf {
+        size_t size;
+        struct file *file;
+        struct list_head attachments;
+        const struct dma_buf_ops *ops;
+        /* mutex to serialize list manipulation and other ops */
+        struct mutex lock;
+        void *priv;
+};
+
+/**
+ * struct dma_buf_attachment - holds device-buffer attachment data
+ * @dmabuf: buffer for this attachment.
+ * @dev: device attached to the buffer.
+ * @node: list of dma_buf_attachment.
+ * @priv: exporter specific attachment data.
+ *
+ * This structure holds the attachment information between the dma_buf buffer
+ * and its user device(s). The list contains one attachment struct per device
+ * attached to the buffer.
+ */
+struct dma_buf_attachment {
+        struct dma_buf *dmabuf;
+        struct device *dev;
+        struct list_head node;
+        void *priv;
+};
+
+#ifdef CONFIG_DMA_SHARED_BUFFER
+struct dma_buf_attachment *dma_buf_attach(struct dma_buf *dmabuf,
+                                                        struct device *dev);
+void dma_buf_detach(struct dma_buf *dmabuf,
+                                struct dma_buf_attachment *dmabuf_attach);
+struct dma_buf *dma_buf_export(void *priv, struct dma_buf_ops *ops,
+                        size_t size, int flags);
+int dma_buf_fd(struct dma_buf *dmabuf);
+struct dma_buf *dma_buf_get(int fd);
+void dma_buf_put(struct dma_buf *dmabuf);
+
+struct sg_table *dma_buf_map_attachment(struct dma_buf_attachment *,
+                                        enum dma_data_direction);
+void dma_buf_unmap_attachment(struct dma_buf_attachment *, struct sg_table *);
+#else
+
+static inline struct dma_buf_attachment *dma_buf_attach(struct dma_buf *dmabuf,
+                                                        struct device *dev)
+{
+        return ERR_PTR(-ENODEV);
+}
+
+static inline void dma_buf_detach(struct dma_buf *dmabuf,
+                                  struct dma_buf_attachment *dmabuf_attach)
+{
+        return;
+}
+
+static inline struct dma_buf *dma_buf_export(void *priv,
+                                                struct dma_buf_ops *ops,
+                                                size_t size, int flags)
+{
+        return ERR_PTR(-ENODEV);
+}
+
+static inline int dma_buf_fd(struct dma_buf *dmabuf)
+{
+        return -ENODEV;
+}
+
+static inline struct dma_buf *dma_buf_get(int fd)
+{
+        return ERR_PTR(-ENODEV);
+}
+
+static inline void dma_buf_put(struct dma_buf *dmabuf)
+{
+        return;
+}
+
+static inline struct sg_table *dma_buf_map_attachment(
+        struct dma_buf_attachment *attach, enum dma_data_direction write)
+{
+        return ERR_PTR(-ENODEV);
+}
+
+static inline void dma_buf_unmap_attachment(struct dma_buf_attachment *attach,
+                                                struct sg_table *sg)
+{
+        return;
+}
+
+#endif /* CONFIG_DMA_SHARED_BUFFER */
+
+#endif /* __DMA_BUF_H__ */