V4L/DVB (11242): allow v4l2 drivers to provide a get_unmapped_area handler

Shared memory mappings on nommu machines require a get_unmapped_area
file operation that suggests an address for the mapping. This patch
adds a way for v4l2 drivers to provide this callback.

Signed-off-by: Daniel Glöckner <dg@emlix.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

2 files changed, 21 insertions, 0 deletions

diff --git a/drivers/media/video/v4l2-dev.c b/drivers/media/video/v4l2-dev.c
index cdc8ce3c4e56..91228b3df07d 100644
--- a/drivers/media/video/v4l2-dev.c
+++ b/drivers/media/video/v4l2-dev.c
@@ -198,6 +198,23 @@ static long v4l2_unlocked_ioctl(struct file *filp,
         return vdev->fops->unlocked_ioctl(filp, cmd, arg);
 }
 
+#ifdef CONFIG_MMU
+#define v4l2_get_unmapped_area NULL
+#else
+static unsigned long v4l2_get_unmapped_area(struct file *filp,
+                unsigned long addr, unsigned long len, unsigned long pgoff,
+                unsigned long flags)
+{
+        struct video_device *vdev = video_devdata(filp);
+
+        if (!vdev->fops->get_unmapped_area)
+                return -ENOSYS;
+        if (video_is_unregistered(vdev))
+                return -ENODEV;
+        return vdev->fops->get_unmapped_area(filp, addr, len, pgoff, flags);
+}
+#endif
+
 static int v4l2_mmap(struct file *filp, struct vm_area_struct *vm)
 {
         struct video_device *vdev = video_devdata(filp);
@@ -250,6 +267,7 @@ static const struct file_operations v4l2_unlocked_fops = {
         .read = v4l2_read,
         .write = v4l2_write,
         .open = v4l2_open,
+        .get_unmapped_area = v4l2_get_unmapped_area,
         .mmap = v4l2_mmap,
         .unlocked_ioctl = v4l2_unlocked_ioctl,
 #ifdef CONFIG_COMPAT
@@ -265,6 +283,7 @@ static const struct file_operations v4l2_fops = {
         .read = v4l2_read,
         .write = v4l2_write,
         .open = v4l2_open,
+        .get_unmapped_area = v4l2_get_unmapped_area,
         .mmap = v4l2_mmap,
         .ioctl = v4l2_ioctl,
 #ifdef CONFIG_COMPAT
diff --git a/include/media/v4l2-dev.h b/include/media/v4l2-dev.h
index e36faab8459b..2058dd45e915 100644
--- a/include/media/v4l2-dev.h
+++ b/include/media/v4l2-dev.h
@@ -40,6 +40,8 @@ struct v4l2_file_operations {
         unsigned int (*poll) (struct file *, struct poll_table_struct *);
         long (*ioctl) (struct file *, unsigned int, unsigned long);
         long (*unlocked_ioctl) (struct file *, unsigned int, unsigned long);
+        unsigned long (*get_unmapped_area) (struct file *, unsigned long,
+                                unsigned long, unsigned long, unsigned long);
         int (*mmap) (struct file *, struct vm_area_struct *);
         int (*open) (struct file *);
         int (*release) (struct file *);