[PATCH] gem: RFC: add support for private objects

[Alan Cox]

These small changes should allow GEM to be used with non shmem objects as
well as shmem objects. In the GMA500 case it allows the base framebuffer to
appear as a GEM object and thus acquire a handle and work with KMS.

For i915 it ought to be trivial to get back the wasted memory but putting the
system fb back into stolen RAM and in general I can imagine it allowing the
use of GEM and thus KMS with all the older cards that have their framebuffer
firmly placed in video RAM.

Signed-off-by: Alan Cox <alan at linux.intel.com>
---

 drivers/gpu/drm/drm_gem.c |   26 ++++++++++++++++++++++++--
 include/drm/drmP.h        |    2 ++
 2 files changed, 26 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/drm_gem.c b/drivers/gpu/drm/drm_gem.c
index 74e4ff5..d3ae55e 100644
--- a/drivers/gpu/drm/drm_gem.c
+++ b/drivers/gpu/drm/drm_gem.c
@@ -128,7 +128,7 @@ drm_gem_destroy(struct drm_device *dev)
 }
 
 /**
- * Initialize an already allocate GEM object of the specified size with
+ * Initialize an already allocated GEM object of the specified size with
  * shmfs backing store.
  */
 int drm_gem_object_init(struct drm_device *dev,
@@ -150,6 +150,27 @@ int drm_gem_object_init(struct drm_device *dev,
 EXPORT_SYMBOL(drm_gem_object_init);
 
 /**
+ * Initialize an already allocated GEM object of the specified size with
+ * no GEM provided backing store. Instead the caller is responsible for
+ * backing the object and handling it.
+ */
+int drm_gem_private_object_init(struct drm_device *dev,
+			struct drm_gem_object *obj, size_t size)
+{
+	BUG_ON((size & (PAGE_SIZE - 1)) != 0);
+
+	obj->dev = dev;
+	obj->filp = NULL;
+
+	kref_init(&obj->refcount);
+	atomic_set(&obj->handle_count, 0);
+	obj->size = size;
+
+	return 0;
+}
+EXPORT_SYMBOL(drm_gem_private_object_init);
+
+/**
  * Allocate a GEM object of the specified size with shmfs backing store
  */
 struct drm_gem_object *
@@ -426,7 +447,8 @@ drm_gem_release(struct drm_device *dev, struct drm_file *file_private)
 void
 drm_gem_object_release(struct drm_gem_object *obj)
 {
-	fput(obj->filp);
+	if (obj->filp)
+	    fput(obj->filp);
 }
 EXPORT_SYMBOL(drm_gem_object_release);
 
diff --git a/include/drm/drmP.h b/include/drm/drmP.h
index 738b3a5..111e98f 100644
--- a/include/drm/drmP.h
+++ b/include/drm/drmP.h
@@ -1539,6 +1539,8 @@ struct drm_gem_object *drm_gem_object_alloc(struct drm_device *dev,
 					    size_t size);
 int drm_gem_object_init(struct drm_device *dev,
 			struct drm_gem_object *obj, size_t size);
+int drm_gem_private_object_init(struct drm_device *dev,
+			struct drm_gem_object *obj, size_t size);
 void drm_gem_object_handle_free(struct drm_gem_object *obj);
 void drm_gem_vm_open(struct vm_area_struct *vma);
 void drm_gem_vm_close(struct vm_area_struct *vma);