drm/i915: Use i915_global_register()

Rather than manually add every new global into each hook, use
i915_global_register() function and keep a list of registered globals to
invoke instead.

However, I haven't found a way for random drivers to add an .init table
to avoid having to manually add ourselves to i915_globals_init() each
time.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20190305213830.18094-1-chris@chris-wilson.co.uk
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>

drivers/gpu/drm/i915/i915_globals.h

@@ -7,9 +7,28 @@
 #ifndef _I915_GLOBALS_H_
 #define _I915_GLOBALS_H_
 
+typedef void (*i915_global_func_t)(void);
+
+struct i915_global {
+	struct list_head link;
+
+	i915_global_func_t shrink;
+	i915_global_func_t exit;
+};
+
+void i915_global_register(struct i915_global *global);
+
 int i915_globals_init(void);
 void i915_globals_park(void);
 void i915_globals_unpark(void);
 void i915_globals_exit(void);
 
+/* constructors */
+int i915_global_active_init(void);
+int i915_global_context_init(void);
+int i915_global_objects_init(void);
+int i915_global_request_init(void);
+int i915_global_scheduler_init(void);
+int i915_global_vma_init(void);
+
 #endif /* _I915_GLOBALS_H_ */