3 files changed, 303 insertions, 0 deletions

diff --git a/drivers/base/Kconfig b/drivers/base/Kconfig
index 21cf46f45245..e95c67edb2cb 100644
--- a/drivers/base/Kconfig
+++ b/drivers/base/Kconfig
@@ -174,4 +174,15 @@ config SYS_HYPERVISOR
 
 source "drivers/base/regmap/Kconfig"
 
+config DMA_SHARED_BUFFER
+        bool "Buffer framework to be shared between drivers"
+        default n
+        select ANON_INODES
+        depends on EXPERIMENTAL
+        help
+          This option enables the framework for buffer-sharing between
+          multiple drivers. A buffer is associated with a file using driver
+          APIs extension; the file's descriptor can then be passed on to other
+          driver.
+
 endmenu
diff --git a/drivers/base/Makefile b/drivers/base/Makefile
index 1334d893b560..2c8272dd93c4 100644
--- a/drivers/base/Makefile
+++ b/drivers/base/Makefile
@@ -9,6 +9,7 @@ obj-$(CONFIG_DEVTMPFS)	+= devtmpfs.o
 obj-y                   += power/
 obj-$(CONFIG_HAS_DMA)   += dma-mapping.o
 obj-$(CONFIG_HAVE_GENERIC_DMA_COHERENT) += dma-coherent.o
+obj-$(CONFIG_DMA_SHARED_BUFFER) += dma-buf.o
 obj-$(CONFIG_ISA)       += isa.o
 obj-$(CONFIG_FW_LOADER) += firmware_class.o
 obj-$(CONFIG_NUMA)      += node.o
diff --git a/drivers/base/dma-buf.c b/drivers/base/dma-buf.c
new file mode 100644
index 000000000000..e38ad243b4bb
--- /dev/null
+++ b/drivers/base/dma-buf.c
@@ -0,0 +1,291 @@
+/*
+ * Framework for buffer objects that can be shared across devices/subsystems.
+ *
+ * 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/>.
+ */
+
+#include <linux/fs.h>
+#include <linux/slab.h>
+#include <linux/dma-buf.h>
+#include <linux/anon_inodes.h>
+#include <linux/export.h>
+
+static inline int is_dma_buf_file(struct file *);
+
+static int dma_buf_release(struct inode *inode, struct file *file)
+{
+        struct dma_buf *dmabuf;
+
+        if (!is_dma_buf_file(file))
+                return -EINVAL;
+
+        dmabuf = file->private_data;
+
+        dmabuf->ops->release(dmabuf);
+        kfree(dmabuf);
+        return 0;
+}
+
+static const struct file_operations dma_buf_fops = {
+        .release        = dma_buf_release,
+};
+
+/*
+ * is_dma_buf_file - Check if struct file* is associated with dma_buf
+ */
+static inline int is_dma_buf_file(struct file *file)
+{
+        return file->f_op == &dma_buf_fops;
+}
+
+/**
+ * dma_buf_export - Creates a new dma_buf, and associates an anon file
+ * with this buffer, so it can be exported.
+ * Also connect the allocator specific data and ops to the buffer.
+ *
+ * @priv:       [in]    Attach private data of allocator to this buffer
+ * @ops:        [in]    Attach allocator-defined dma buf ops to the new buffer.
+ * @size:       [in]    Size of the buffer
+ * @flags:      [in]    mode flags for the file.
+ *
+ * Returns, on success, a newly created dma_buf object, which wraps the
+ * supplied private data and operations for dma_buf_ops. On either missing
+ * ops, or error in allocating struct dma_buf, will return negative error.
+ *
+ */
+struct dma_buf *dma_buf_export(void *priv, struct dma_buf_ops *ops,
+                                size_t size, int flags)
+{
+        struct dma_buf *dmabuf;
+        struct file *file;
+
+        if (WARN_ON(!priv || !ops
+                          || !ops->map_dma_buf
+                          || !ops->unmap_dma_buf
+                          || !ops->release)) {
+                return ERR_PTR(-EINVAL);
+        }
+
+        dmabuf = kzalloc(sizeof(struct dma_buf), GFP_KERNEL);
+        if (dmabuf == NULL)
+                return ERR_PTR(-ENOMEM);
+
+        dmabuf->priv = priv;
+        dmabuf->ops = ops;
+        dmabuf->size = size;
+
+        file = anon_inode_getfile("dmabuf", &dma_buf_fops, dmabuf, flags);
+
+        dmabuf->file = file;
+
+        mutex_init(&dmabuf->lock);
+        INIT_LIST_HEAD(&dmabuf->attachments);
+
+        return dmabuf;
+}
+EXPORT_SYMBOL_GPL(dma_buf_export);
+
+
+/**
+ * dma_buf_fd - returns a file descriptor for the given dma_buf
+ * @dmabuf:     [in]    pointer to dma_buf for which fd is required.
+ *
+ * On success, returns an associated 'fd'. Else, returns error.
+ */
+int dma_buf_fd(struct dma_buf *dmabuf)
+{
+        int error, fd;
+
+        if (!dmabuf || !dmabuf->file)
+                return -EINVAL;
+
+        error = get_unused_fd();
+        if (error < 0)
+                return error;
+        fd = error;
+
+        fd_install(fd, dmabuf->file);
+
+        return fd;
+}
+EXPORT_SYMBOL_GPL(dma_buf_fd);
+
+/**
+ * dma_buf_get - returns the dma_buf structure related to an fd
+ * @fd: [in]    fd associated with the dma_buf to be returned
+ *
+ * On success, returns the dma_buf structure associated with an fd; uses
+ * file's refcounting done by fget to increase refcount. returns ERR_PTR
+ * otherwise.
+ */
+struct dma_buf *dma_buf_get(int fd)
+{
+        struct file *file;
+
+        file = fget(fd);
+
+        if (!file)
+                return ERR_PTR(-EBADF);
+
+        if (!is_dma_buf_file(file)) {
+                fput(file);
+                return ERR_PTR(-EINVAL);
+        }
+
+        return file->private_data;
+}
+EXPORT_SYMBOL_GPL(dma_buf_get);
+
+/**
+ * dma_buf_put - decreases refcount of the buffer
+ * @dmabuf:     [in]    buffer to reduce refcount of
+ *
+ * Uses file's refcounting done implicitly by fput()
+ */
+void dma_buf_put(struct dma_buf *dmabuf)
+{
+        if (WARN_ON(!dmabuf || !dmabuf->file))
+                return;
+
+        fput(dmabuf->file);
+}
+EXPORT_SYMBOL_GPL(dma_buf_put);
+
+/**
+ * dma_buf_attach - Add the device to dma_buf's attachments list; optionally,
+ * calls attach() of dma_buf_ops to allow device-specific attach functionality
+ * @dmabuf:     [in]    buffer to attach device to.
+ * @dev:        [in]    device to be attached.
+ *
+ * Returns struct dma_buf_attachment * for this attachment; may return negative
+ * error codes.
+ *
+ */
+struct dma_buf_attachment *dma_buf_attach(struct dma_buf *dmabuf,
+                                          struct device *dev)
+{
+        struct dma_buf_attachment *attach;
+        int ret;
+
+        if (WARN_ON(!dmabuf || !dev || !dmabuf->ops))
+                return ERR_PTR(-EINVAL);
+
+        attach = kzalloc(sizeof(struct dma_buf_attachment), GFP_KERNEL);
+        if (attach == NULL)
+                goto err_alloc;
+
+        mutex_lock(&dmabuf->lock);
+
+        attach->dev = dev;
+        attach->dmabuf = dmabuf;
+        if (dmabuf->ops->attach) {
+                ret = dmabuf->ops->attach(dmabuf, dev, attach);
+                if (ret)
+                        goto err_attach;
+        }
+        list_add(&attach->node, &dmabuf->attachments);
+
+        mutex_unlock(&dmabuf->lock);
+        return attach;
+
+err_alloc:
+        return ERR_PTR(-ENOMEM);
+err_attach:
+        kfree(attach);
+        mutex_unlock(&dmabuf->lock);
+        return ERR_PTR(ret);
+}
+EXPORT_SYMBOL_GPL(dma_buf_attach);
+
+/**
+ * dma_buf_detach - Remove the given attachment from dmabuf's attachments list;
+ * optionally calls detach() of dma_buf_ops for device-specific detach
+ * @dmabuf:     [in]    buffer to detach from.
+ * @attach:     [in]    attachment to be detached; is free'd after this call.
+ *
+ */
+void dma_buf_detach(struct dma_buf *dmabuf, struct dma_buf_attachment *attach)
+{
+        if (WARN_ON(!dmabuf || !attach || !dmabuf->ops))
+                return;
+
+        mutex_lock(&dmabuf->lock);
+        list_del(&attach->node);
+        if (dmabuf->ops->detach)
+                dmabuf->ops->detach(dmabuf, attach);
+
+        mutex_unlock(&dmabuf->lock);
+        kfree(attach);
+}
+EXPORT_SYMBOL_GPL(dma_buf_detach);
+
+/**
+ * dma_buf_map_attachment - Returns the scatterlist table of the attachment;
+ * mapped into _device_ address space. Is a wrapper for map_dma_buf() of the
+ * dma_buf_ops.
+ * @attach:     [in]    attachment whose scatterlist is to be returned
+ * @direction:  [in]    direction of DMA transfer
+ *
+ * Returns sg_table containing the scatterlist to be returned; may return NULL
+ * or ERR_PTR.
+ *
+ */
+struct sg_table *dma_buf_map_attachment(struct dma_buf_attachment *attach,
+                                        enum dma_data_direction direction)
+{
+        struct sg_table *sg_table = ERR_PTR(-EINVAL);
+
+        might_sleep();
+
+        if (WARN_ON(!attach || !attach->dmabuf || !attach->dmabuf->ops))
+                return ERR_PTR(-EINVAL);
+
+        mutex_lock(&attach->dmabuf->lock);
+        if (attach->dmabuf->ops->map_dma_buf)
+                sg_table = attach->dmabuf->ops->map_dma_buf(attach, direction);
+        mutex_unlock(&attach->dmabuf->lock);
+
+        return sg_table;
+}
+EXPORT_SYMBOL_GPL(dma_buf_map_attachment);
+
+/**
+ * dma_buf_unmap_attachment - unmaps and decreases usecount of the buffer;might
+ * deallocate the scatterlist associated. Is a wrapper for unmap_dma_buf() of
+ * dma_buf_ops.
+ * @attach:     [in]    attachment to unmap buffer from
+ * @sg_table:   [in]    scatterlist info of the buffer to unmap
+ *
+ */
+void dma_buf_unmap_attachment(struct dma_buf_attachment *attach,
+                                struct sg_table *sg_table)
+{
+        if (WARN_ON(!attach || !attach->dmabuf || !sg_table
+                            || !attach->dmabuf->ops))
+                return;
+
+        mutex_lock(&attach->dmabuf->lock);
+        if (attach->dmabuf->ops->unmap_dma_buf)
+                attach->dmabuf->ops->unmap_dma_buf(attach, sg_table);
+        mutex_unlock(&attach->dmabuf->lock);
+
+}
+EXPORT_SYMBOL_GPL(dma_buf_unmap_attachment);