drm/i915: Move ringbuffer-related code to intel_ringbuffer.c.

This is preparation for supporting multiple ringbuffers on Ironlake.
The non-copy-and-paste changes are:
- de-staticing functions
- I915_GEM_GPU_DOMAINS moving to i915_drv.h to be used by both files.
- i915_gem_add_request had only half its implementation
  copy-and-pasted out of the middle of it.
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 7f797ef..114653a 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -31,6 +31,7 @@
 #define _I915_DRV_H_
 
 #include "i915_reg.h"
+#include "i915_drm.h"
 #include "intel_bios.h"
 #include <linux/io-mapping.h>
 
@@ -55,6 +56,8 @@
 
 #define I915_NUM_PIPE	2
 
+#define I915_GEM_GPU_DOMAINS	(~(I915_GEM_DOMAIN_CPU | I915_GEM_DOMAIN_GTT))
+
 /* Interface history:
  *
  * 1.1: Original.
@@ -849,6 +852,9 @@
 extern int i915_vblank_swap(struct drm_device *dev, void *data,
 			    struct drm_file *file_priv);
 extern void i915_enable_irq(drm_i915_private_t *dev_priv, u32 mask);
+extern void i915_disable_irq(drm_i915_private_t *dev_priv, u32 mask);
+void ironlake_enable_graphics_irq(drm_i915_private_t *dev_priv, u32 mask);
+void ironlake_disable_graphics_irq(drm_i915_private_t *dev_priv, u32 mask);
 
 void
 i915_enable_pipestat(drm_i915_private_t *dev_priv, int pipe, u32 mask);
@@ -956,6 +962,8 @@
 
 void i915_gem_shrinker_init(void);
 void i915_gem_shrinker_exit(void);
+int i915_gem_init_pipe_control(struct drm_device *dev);
+void i915_gem_cleanup_pipe_control(struct drm_device *dev);
 
 /* i915_gem_tiling.c */
 void i915_gem_detect_bit_6_swizzle(struct drm_device *dev);
@@ -1006,6 +1014,16 @@
 static inline void opregion_enable_asle(struct drm_device *dev) { return; }
 #endif
 
+/* intel_ringbuffer.c */
+extern void i915_gem_flush(struct drm_device *dev,
+			   uint32_t invalidate_domains,
+			   uint32_t flush_domains);
+extern int i915_dispatch_gem_execbuffer(struct drm_device *dev,
+					struct drm_i915_gem_execbuffer2 *exec,
+					struct drm_clip_rect *cliprects,
+					uint64_t exec_offset);
+extern uint32_t i915_ring_add_request(struct drm_device *dev);
+
 /* modesetting */
 extern void intel_modeset_init(struct drm_device *dev);
 extern void intel_modeset_cleanup(struct drm_device *dev);