usb: gadget/uvc: Add support for 'get_unmapped_area' for MMUless architectures

This patch adds the support for 'get_unmapped_area' in UVC gadget
which is called when the 'mmap' system call is executed on MMUless
architectures.
Signed-off-by: Bhupesh Sharma <bhupesh.sharma@st.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

drivers/usb/gadget/uvc_queue.c

@@ -232,6 +232,24 @@ static int uvc_queue_mmap(struct uvc_video_queue *queue,
 	return ret;
 }
 
+#ifndef CONFIG_MMU
+/*
+ * Get unmapped area.
+ *
+ * NO-MMU arch need this function to make mmap() work correctly.
+ */
+static unsigned long uvc_queue_get_unmapped_area(struct uvc_video_queue *queue,
+		unsigned long pgoff)
+{
+	unsigned long ret;
+
+	mutex_lock(&queue->mutex);
+	ret = vb2_get_unmapped_area(&queue->queue, 0, 0, pgoff, 0);
+	mutex_unlock(&queue->mutex);
+	return ret;
+}
+#endif
+
 /*
  * Cancel the video buffers queue.
  *

drivers/usb/gadget/uvc_v4l2.c

@@ -339,6 +339,18 @@ uvc_v4l2_poll(struct file *file, poll_table *wait)
 	return uvc_queue_poll(&uvc->video.queue, file, wait);
 }
 
+#ifndef CONFIG_MMU
+static unsigned long uvc_v4l2_get_unmapped_area(struct file *file,
+		unsigned long addr, unsigned long len, unsigned long pgoff,
+		unsigned long flags)
+{
+	struct video_device *vdev = video_devdata(file);
+	struct uvc_device *uvc = video_get_drvdata(vdev);
+
+	return uvc_queue_get_unmapped_area(&uvc->video.queue, pgoff);
+}
+#endif
+
 static struct v4l2_file_operations uvc_v4l2_fops = {
 	.owner		= THIS_MODULE,
 	.open		= uvc_v4l2_open,
@@ -346,5 +358,8 @@ static struct v4l2_file_operations uvc_v4l2_fops = {
 	.ioctl		= uvc_v4l2_ioctl,
 	.mmap		= uvc_v4l2_mmap,
 	.poll		= uvc_v4l2_poll,
+#ifndef CONFIG_MMU
+	.get_unmapped_area = uvc_v4l2_get_unmapped_area,
+#endif
 };