BACKPORT: drm/fence: add fence timeline to drm_crtc

Create one timeline context for each CRTC to be able to handle out-fences
and signal them. It adds a few members to struct drm_crtc: fence_context,
where we store the context we get from fence_context_alloc(), the
fence seqno and the fence lock, that we pass in fence_init() to be
used by the fence.

v2: Comment by Daniel Stone:
	- add BUG_ON() to fence_to_crtc() macro

v3: Comment by Ville Syrjälä
	- Use more meaningful name as crtc timeline name

v4: Comments by Brian Starkey
	- Use even more meaninful name for the crtc timeline
	- add doc for timeline_name
    Comment by Daniel Vetter
	- use in-line style for comments

	- rebase after fence -> dma_fence rename [removed in
	  backport to Android common kernel 4.9]

v5: Comment by Daniel Vetter
	- Add doc for drm_crtc_fence_ops

v6: Comment by Chris Wilson
	- Move fence_to_crtc to drm_crtc.c
	- Move export of drm_crtc_fence_ops to drm_crtc_internal.h

    - rebase against latest drm-misc

Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.co.uk>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch> (v5)
Reviewed-by: Sean Paul <seanpaul@chromium.org> (v5)
Tested-by: Robert Foss <robert.foss@collabora.com> (v5)
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1479220628-10204-1-git-send-email-gustavo@padovan.org
(cherry picked from commit 6d6003c4b613c93973e4e870d83f4bed2ad9ac34)
Signed-off-by: Marissa Wall <marissaw@google.com>

Change-Id: Id1722e5611757509ec311b56c70fa985a2d5035a
diff --git a/include/drm/drm_crtc.h b/include/drm/drm_crtc.h
index 3851b68..8d636c6 100644
--- a/include/drm/drm_crtc.h
+++ b/include/drm/drm_crtc.h
@@ -680,6 +680,35 @@
 	 * context.
 	 */
 	struct drm_modeset_acquire_ctx *acquire_ctx;
+
+	/**
+	 * @fence_context:
+	 *
+	 * timeline context used for fence operations.
+	 */
+	unsigned int fence_context;
+
+	/**
+	 * @fence_lock:
+	 *
+	 * spinlock to protect the fences in the fence_context.
+	 */
+
+	spinlock_t fence_lock;
+	/**
+	 * @fence_seqno:
+	 *
+	 * Seqno variable used as monotonic counter for the fences
+	 * created on the CRTC's timeline.
+	 */
+	unsigned long fence_seqno;
+
+	/**
+	 * @timeline_name:
+	 *
+	 * The name of the CRTC's fence timeline.
+	 */
+	char timeline_name[32];
 };
 
 /**