reservation: add support for fences to enable cross-device synchronisation

Signed-off-by: Maarten Lankhorst <maarten.lankhorst@canonical.com>
Acked-by: Sumit Semwal <sumit.semwal@linaro.org>
Acked-by: Daniel Vetter <daniel@ffwll.ch>
Reviewed-by: Rob Clark <robdclark@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

include/linux/reservation.h

@@ -6,7 +6,7 @@
  * Copyright (C) 2012 Texas Instruments
  *
  * Authors:
- * Rob Clark <rob.clark@linaro.org>
+ * Rob Clark <robdclark@gmail.com>
  * Maarten Lankhorst <maarten.lankhorst@canonical.com>
  * Thomas Hellstrom <thellstrom-at-vmware-dot-com>
  *
@@ -40,22 +40,40 @@
 #define _LINUX_RESERVATION_H
 
 #include <linux/ww_mutex.h>
+#include <linux/fence.h>
+#include <linux/slab.h>
 
 extern struct ww_class reservation_ww_class;
 
 struct reservation_object {
 	struct ww_mutex lock;
+
+	struct fence *fence_excl;
+	struct fence **fence_shared;
+	u32 fence_shared_count, fence_shared_max;
 };
 
 static inline void
 reservation_object_init(struct reservation_object *obj)
 {
 	ww_mutex_init(&obj->lock, &reservation_ww_class);
+
+	obj->fence_shared_count = obj->fence_shared_max = 0;
+	obj->fence_shared = NULL;
+	obj->fence_excl = NULL;
 }
 
 static inline void
 reservation_object_fini(struct reservation_object *obj)
 {
+	int i;
+
+	if (obj->fence_excl)
+		fence_put(obj->fence_excl);
+	for (i = 0; i < obj->fence_shared_count; ++i)
+		fence_put(obj->fence_shared[i]);
+	kfree(obj->fence_shared);
+
 	ww_mutex_destroy(&obj->lock);
 }