drm/i915/display: start a buffer object abstraction layer

The display code needs to deal with gem objects, and mostly uses struct
drm_i915_gem_object. That's not great, because for xe we need to
redefine it struct xe_bo during build.

Start a common interface using struct drm_gem_object, with separate
implementations for i915 and xe. For starters, convert i9xx_wm.c to use
it.

Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Acked-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/df6867523a0b5fdd4eb63f657f545603ae6f6e0b.1726589119.git.jani.nikula@intel.com

drivers/gpu/drm/i915/Makefile

@@ -225,6 +225,7 @@ i915-y += \
 	display/intel_atomic_plane.o \
 	display/intel_audio.o \
 	display/intel_bios.o \
+	display/intel_bo.o \
 	display/intel_bw.o \
 	display/intel_cdclk.o \
 	display/intel_color.o \

drivers/gpu/drm/i915/display/i9xx_wm.c

@@ -7,6 +7,7 @@
 #include "i915_reg.h"
 #include "i9xx_wm.h"
 #include "intel_atomic.h"
+#include "intel_bo.h"
 #include "intel_display.h"
 #include "intel_display_trace.h"
 #include "intel_fb.h"
@@ -2185,12 +2186,12 @@ static void i9xx_update_wm(struct drm_i915_private *dev_priv)
 
 	crtc = single_enabled_crtc(dev_priv);
 	if (IS_I915GM(dev_priv) && crtc) {
-		struct drm_i915_gem_object *obj;
+		struct drm_gem_object *obj;
 
-		obj = intel_fb_obj(crtc->base.primary->state->fb);
+		obj = intel_fb_bo(crtc->base.primary->state->fb);
 
 		/* self-refresh seems busted with untiled */
-		if (!i915_gem_object_is_tiled(obj))
+		if (!intel_bo_is_tiled(obj))
 			crtc = NULL;
 	}
 

drivers/gpu/drm/i915/display/intel_bo.c

@@ -0,0 +1,10 @@
+// SPDX-License-Identifier: MIT
+/* Copyright © 2024 Intel Corporation */
+
+#include "gem/i915_gem_object.h"
+#include "intel_bo.h"
+
+bool intel_bo_is_tiled(struct drm_gem_object *obj)
+{
+	return i915_gem_object_is_tiled(to_intel_bo(obj));
+}

drivers/gpu/drm/i915/display/intel_bo.h

@@ -0,0 +1,13 @@
+/* SPDX-License-Identifier: MIT */
+/* Copyright © 2024 Intel Corporation */
+
+#ifndef __INTEL_BO__
+#define __INTEL_BO__
+
+#include <linux/types.h>
+
+struct drm_gem_object;
+
+bool intel_bo_is_tiled(struct drm_gem_object *obj);
+
+#endif /* __INTEL_BO__ */

drivers/gpu/drm/i915/display/intel_fb.c

@@ -2125,3 +2125,8 @@ struct drm_i915_gem_object *intel_fb_obj(const struct drm_framebuffer *fb)
 {
 	return fb ? to_intel_bo(fb->obj[0]) : NULL;
 }
+
+struct drm_gem_object *intel_fb_bo(const struct drm_framebuffer *fb)
+{
+	return fb ? fb->obj[0] : NULL;
+}

drivers/gpu/drm/i915/display/intel_fb.h

@@ -12,6 +12,7 @@
 struct drm_device;
 struct drm_file;
 struct drm_framebuffer;
+struct drm_gem_object;
 struct drm_i915_gem_object;
 struct drm_i915_private;
 struct drm_mode_fb_cmd2;
@@ -98,4 +99,6 @@ unsigned int intel_fb_modifier_to_tiling(u64 fb_modifier);
 
 struct drm_i915_gem_object *intel_fb_obj(const struct drm_framebuffer *fb);
 
+struct drm_gem_object *intel_fb_bo(const struct drm_framebuffer *fb);
+
 #endif /* __INTEL_FB_H__ */

drivers/gpu/drm/xe/Makefile

@@ -165,6 +165,7 @@ $(obj)/i915-display/%.o: $(srctree)/drivers/gpu/drm/i915/display/%.c FORCE
 xe-$(CONFIG_DRM_XE_DISPLAY) += \
 	display/ext/i915_irq.o \
 	display/ext/i915_utils.o \
+	display/intel_bo.o \
 	display/intel_fb_bo.o \
 	display/intel_fbdev_fb.o \
 	display/xe_display.o \

drivers/gpu/drm/xe/display/intel_bo.c

@@ -0,0 +1,12 @@
+// SPDX-License-Identifier: MIT
+/* Copyright © 2024 Intel Corporation */
+
+#include <drm/drm_gem.h>
+
+#include "intel_bo.h"
+
+bool intel_bo_is_tiled(struct drm_gem_object *obj)
+{
+	/* legacy tiling is unused */
+	return false;
+}