[PATCH 2/3] dma-buf: Add ioctls to allow userspace to flush

[Tiago Vignatti]

From: Daniel Vetter <daniel.vetter at ffwll.ch>

FIXME: Update kerneldoc for begin/end to make it clear that those are
for mmap too.

Open: Do we need a special indication that the begin/end is from
userspace mmap and not from kernel mmap?

There's also the question already about kernel internal users - vmap
and kmap interfaces are much different ... We might need to add a
mapping enum to the begin/end dma-buf functions.

v2 (Tiago): Fix header file type names (u64 -> __u64)

Signed-off-by: Daniel Vetter <daniel.vetter at intel.com>
Signed-off-by: Tiago Vignatti <tiago.vignatti at intel.com>
---
 drivers/dma-buf/dma-buf.c    | 47 ++++++++++++++++++++++++++++++++++++++++++++
 include/uapi/linux/dma-buf.h | 39 ++++++++++++++++++++++++++++++++++++
 2 files changed, 86 insertions(+)
 create mode 100644 include/uapi/linux/dma-buf.h

diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
index 155c146..4820d61 100644
--- a/drivers/dma-buf/dma-buf.c
+++ b/drivers/dma-buf/dma-buf.c
@@ -34,6 +34,8 @@
 #include <linux/poll.h>
 #include <linux/reservation.h>
 
+#include <uapi/linux/dma-buf.h>
+
 static inline int is_dma_buf_file(struct file *);
 
 struct dma_buf_list {
@@ -251,11 +253,56 @@ out:
 	return events;
 }
 
+static long dma_buf_ioctl(struct file *file,
+			  unsigned int cmd, unsigned long arg)
+{
+	struct dma_buf *dmabuf;
+	struct dma_buf_sync sync;
+	enum dma_data_direction direction;
+
+	dmabuf = file->private_data;
+
+	if (!is_dma_buf_file(file))
+		return -EINVAL;
+
+	switch (cmd) {
+	case DMA_BUF_IOCTL_SYNC:
+		if (copy_from_user(&sync, (void __user *) arg, sizeof(sync)))
+			return -EFAULT;
+
+		if (sync.flags & DMA_BUF_SYNC_RW)
+			direction = DMA_BIDIRECTIONAL;
+		else if (sync.flags & DMA_BUF_SYNC_READ)
+			direction = DMA_FROM_DEVICE;
+		else if (sync.flags & DMA_BUF_SYNC_WRITE)
+			direction = DMA_TO_DEVICE;
+		else
+			return -EINVAL;
+
+		if (sync.flags & ~DMA_BUF_SYNC_VALID_FLAGS_MASK)
+			return -EINVAL;
+
+		/* FIXME: Check for overflows in start/length. */
+
+		if (sync.flags & DMA_BUF_SYNC_END)
+			dma_buf_end_cpu_access(dmabuf, sync.start,
+					       sync.length, direction);
+		else
+			dma_buf_begin_cpu_access(dmabuf, sync.start,
+						 sync.length, direction);
+
+		return 0;
+	default:
+		return -ENOTTY;
+	}
+}
+
 static const struct file_operations dma_buf_fops = {
 	.release	= dma_buf_release,
 	.mmap		= dma_buf_mmap_internal,
 	.llseek		= dma_buf_llseek,
 	.poll		= dma_buf_poll,
+	.unlocked_ioctl	= dma_buf_ioctl,
 };
 
 /*
diff --git a/include/uapi/linux/dma-buf.h b/include/uapi/linux/dma-buf.h
new file mode 100644
index 0000000..e5327df
--- /dev/null
+++ b/include/uapi/linux/dma-buf.h
@@ -0,0 +1,39 @@
+/*
+ * Framework for buffer objects that can be shared across devices/subsystems.
+ *
+ * Copyright(C) 2015 Intel Ltd
+ *
+ * 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_UAPI_H_
+#define _DMA_BUF_UAPI_H_
+
+struct dma_buf_sync {
+	__u64 flags;
+	__u64 start;
+	__u64 length;
+};
+
+#define DMA_BUF_SYNC_READ	(1 << 0)
+#define DMA_BUF_SYNC_WRITE	(2 << 0)
+#define DMA_BUF_SYNC_RW		(3 << 0)
+#define DMA_BUF_SYNC_START	(0 << 2)
+#define DMA_BUF_SYNC_END	(1 << 2)
+#define DMA_BUF_SYNC_VALID_FLAGS_MASK \
+	(DMA_BUF_SYNC_RW | DMA_BUF_SYNC_END)
+
+#define DMA_BUF_BASE		'b'
+#define DMA_BUF_IOCTL_SYNC	_IOWR(DMA_BUF_BASE, 0, struct dma_buf_sync)
+
+#endif
-- 
2.1.0