gma500: introduce the GTT and MMU handling logic

This fits alongside the GEM support to manage our resources on the card
itself. It's not actually clear we need to configure the MMU at all.
Further research is needed before removing it entirely. For now we suck it
in (slightly abused) from the old semi-free driver.
Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

drivers/gpu/drm/gma500/gtt.h

+/**************************************************************************
+ * Copyright (c) 2007-2008, Intel Corporation.
+ * All Rights Reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ **************************************************************************/
+
+#ifndef _PSB_GTT_H_
+#define _PSB_GTT_H_
+
+#include <drm/drmP.h>
+
+/* This wants cleaning up with respect to the psb_dev and un-needed stuff */
+struct psb_gtt {
+	uint32_t gatt_start;
+	uint32_t mmu_gatt_start;
+	uint32_t gtt_start;
+	uint32_t gtt_phys_start;
+	unsigned gtt_pages;
+	unsigned gatt_pages;
+	unsigned long stolen_size;
+	unsigned long vram_stolen_size;
+	struct rw_semaphore sem;
+};
+
+/* Exported functions */
+extern int psb_gtt_init(struct drm_device *dev, int resume);
+extern void psb_gtt_takedown(struct drm_device *dev);
+
+/* Each gtt_range describes an allocation in the GTT area */
+struct gtt_range {
+	struct resource resource;	/* Resource for our allocation */
+	u32 offset;			/* GTT offset of our object */
+	struct drm_gem_object gem;	/* GEM high level stuff */
+	int in_gart;			/* Currently in the GART (ref ct) */
+	bool stolen;			/* Backed from stolen RAM */
+	bool mmapping;			/* Is mmappable */
+	struct page **pages;		/* Backing pages if present */
+	int npage;			/* Number of backing pages */
+};
+
+extern struct gtt_range *psb_gtt_alloc_range(struct drm_device *dev, int len,
+						const char *name, int backed);
+extern void psb_gtt_kref_put(struct gtt_range *gt);
+extern void psb_gtt_free_range(struct drm_device *dev, struct gtt_range *gt);
+extern int psb_gtt_pin(struct gtt_range *gt);
+extern void psb_gtt_unpin(struct gtt_range *gt);
+
+#endif