drm/i915: extract gem/i915_gem_stolen.h from i915_drv.h

It used to be handy that we only had a couple of headers, but over time
i915_drv.h has become unwieldy. Extract declarations to a separate
header file corresponding to the implementation module, clarifying the
modularity of the driver.

Ensure the new header is self-contained, and do so with minimal further
includes, using forward declarations as needed. Include the new header
from i915_drv.h to avoid sprinkling includes all over the place; this
can be changed as a follow-up if necessary.

No functional changes.

Reviewed-by: Chris Wilson <[e-mail]>
Signed-off-by: Jani Nikula <[e-mail]>
Link: https://patchwork.freedesktop.org/patch/msgid/014[e-mail]

drivers/gpu/drm/i915/gem/i915_gem_stolen.c

···
 #include <drm/i915_drm.h>
 
 #include "i915_drv.h"
+#include "i915_gem_stolen.h"
 
 /*
  * The BIOS typically reserves some of the system's memory for the exclusive

drivers/gpu/drm/i915/gem/i915_gem_stolen.h

···
+/* SPDX-License-Identifier: MIT */
+/*
+ * Copyright © 2019 Intel Corporation
+ */
+
+#ifndef __I915_GEM_STOLEN_H__
+#define __I915_GEM_STOLEN_H__
+
+#include <linux/types.h>
+
+struct drm_i915_private;
+struct drm_mm_node;
+struct drm_i915_gem_object;
+
+int i915_gem_stolen_insert_node(struct drm_i915_private *dev_priv,
+				struct drm_mm_node *node, u64 size,
+				unsigned alignment);
+int i915_gem_stolen_insert_node_in_range(struct drm_i915_private *dev_priv,
+					 struct drm_mm_node *node, u64 size,
+					 unsigned alignment, u64 start,
+					 u64 end);
+void i915_gem_stolen_remove_node(struct drm_i915_private *dev_priv,
+				 struct drm_mm_node *node);
+int i915_gem_init_stolen(struct drm_i915_private *dev_priv);
+void i915_gem_cleanup_stolen(struct drm_i915_private *dev_priv);
+struct drm_i915_gem_object *
+i915_gem_object_create_stolen(struct drm_i915_private *dev_priv,
+			      resource_size_t size);
+struct drm_i915_gem_object *
+i915_gem_object_create_stolen_for_preallocated(struct drm_i915_private *dev_priv,
+					       resource_size_t stolen_offset,
+					       resource_size_t gtt_offset,
+					       resource_size_t size);
+
+#endif /* __I915_GEM_STOLEN_H__ */

drivers/gpu/drm/i915/gt/intel_gt.c

···
  */
 
 #include "i915_drv.h"
-
 #include "intel_gt.h"
 #include "intel_gt_pm.h"
 #include "intel_uncore.h"

drivers/gpu/drm/i915/i915_drv.h

···
 #include "display/intel_frontbuffer.h"
 #include "display/intel_opregion.h"
 
+#include "gem/i915_gem_context_types.h"
+#include "gem/i915_gem_stolen.h"
+
 #include "gt/intel_lrc.h"
 #include "gt/intel_engine.h"
 #include "gt/intel_gt_types.h"
···
 #include "intel_wopcm.h"
 
 #include "i915_gem.h"
-#include "gem/i915_gem_context_types.h"
 #include "i915_gem_fence_reg.h"
 #include "i915_gem_gtt.h"
 #include "i915_gpu_error.h"
···
 					 struct drm_mm_node *node,
 					 unsigned int flags);
 int i915_gem_evict_vm(struct i915_address_space *vm);
-
-/* i915_gem_stolen.c */
-int i915_gem_stolen_insert_node(struct drm_i915_private *dev_priv,
-				struct drm_mm_node *node, u64 size,
-				unsigned alignment);
-int i915_gem_stolen_insert_node_in_range(struct drm_i915_private *dev_priv,
-					 struct drm_mm_node *node, u64 size,
-					 unsigned alignment, u64 start,
-					 u64 end);
-void i915_gem_stolen_remove_node(struct drm_i915_private *dev_priv,
-				 struct drm_mm_node *node);
-int i915_gem_init_stolen(struct drm_i915_private *dev_priv);
-void i915_gem_cleanup_stolen(struct drm_i915_private *dev_priv);
-struct drm_i915_gem_object *
-i915_gem_object_create_stolen(struct drm_i915_private *dev_priv,
-			      resource_size_t size);
-struct drm_i915_gem_object *
-i915_gem_object_create_stolen_for_preallocated(struct drm_i915_private *dev_priv,
-					       resource_size_t stolen_offset,
-					       resource_size_t gtt_offset,
-					       resource_size_t size);
 
 /* i915_gem_internal.c */
 struct drm_i915_gem_object *