gma500: GEM and GEM glue

The driver uses GEM along with a couple of small bits of wrapping of its
own. The only real oddity here is the support for using the 'stolen' memory
rather than wasting several MB.

We use a simple resource manager as we don't need to manage our space
intensively at all as we only do 2D work. We also have a GTT which is
entirely GPU facing so in the Cedarview case are not even allocating from
host address space.
Signed-off-by: Alan Cox <alan@linux.intel.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Dave Airlie <airlied@redhat.com>

drivers/gpu/drm/gma500/gem.c

+/*
+ *  psb GEM interface
+ *
+ * Copyright (c) 2011, Intel Corporation.
+ *
+ * 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.
+ *
+ * Authors: Alan Cox
+ *
+ * TODO:
+ *	-	we need to work out if the MMU is relevant (eg for
+ *		accelerated operations on a GEM object)
+ */
+
+#include <drm/drmP.h>
+#include <drm/drm.h>
+#include "psb_drm.h"
+#include "psb_drv.h"
+
+int psb_gem_init_object(struct drm_gem_object *obj)
+{
+	return -EINVAL;
+}
+
+void psb_gem_free_object(struct drm_gem_object *obj)
+{
+	struct gtt_range *gtt = container_of(obj, struct gtt_range, gem);
+	drm_gem_object_release_wrap(obj);
+	/* This must occur last as it frees up the memory of the GEM object */
+	psb_gtt_free_range(obj->dev, gtt);
+}
+
+int psb_gem_get_aperture(struct drm_device *dev, void *data,
+				struct drm_file *file)
+{
+	return -EINVAL;
+}
+
+/**
+ *	psb_gem_dumb_map_gtt	-	buffer mapping for dumb interface
+ *	@file: our drm client file
+ *	@dev: drm device
+ *	@handle: GEM handle to the object (from dumb_create)
+ *
+ *	Do the necessary setup to allow the mapping of the frame buffer
+ *	into user memory. We don't have to do much here at the moment.
+ */
+int psb_gem_dumb_map_gtt(struct drm_file *file, struct drm_device *dev,
+			 uint32_t handle, uint64_t *offset)
+{
+	int ret = 0;
+	struct drm_gem_object *obj;
+
+	if (!(dev->driver->driver_features & DRIVER_GEM))
+		return -ENODEV;
+
+	mutex_lock(&dev->struct_mutex);
+
+	/* GEM does all our handle to object mapping */
+	obj = drm_gem_object_lookup(dev, file, handle);
+	if (obj == NULL) {
+		ret = -ENOENT;
+		goto unlock;
+	}
+	/* What validation is needed here ? */
+
+	/* Make it mmapable */
+	if (!obj->map_list.map) {
+		ret = gem_create_mmap_offset(obj);
+		if (ret)
+			goto out;
+	}
+	/* GEM should really work out the hash offsets for us */
+	*offset = (u64)obj->map_list.hash.key << PAGE_SHIFT;
+out:
+	drm_gem_object_unreference(obj);
+unlock:
+	mutex_unlock(&dev->struct_mutex);
+	return ret;
+}
+
+/**
+ *	psb_gem_create		-	create a mappable object
+ *	@file: the DRM file of the client
+ *	@dev: our device
+ *	@size: the size requested
+ *	@handlep: returned handle (opaque number)
+ *
+ *	Create a GEM object, fill in the boilerplate and attach a handle to
+ *	it so that userspace can speak about it. This does the core work
+ *	for the various methods that do/will create GEM objects for things
+ */
+static int psb_gem_create(struct drm_file *file,
+	struct drm_device *dev, uint64_t size, uint32_t *handlep)
+{
+	struct gtt_range *r;
+	int ret;
+	u32 handle;
+
+	size = roundup(size, PAGE_SIZE);
+
+	/* Allocate our object - for now a direct gtt range which is not
+	   stolen memory backed */
+	r = psb_gtt_alloc_range(dev, size, "gem", 0);
+	if (r == NULL) {
+		dev_err(dev->dev, "no memory for %lld byte GEM object\n", size);
+		return -ENOSPC;
+	}
+	/* Initialize the extra goodies GEM needs to do all the hard work */
+	if (drm_gem_object_init(dev, &r->gem, size) != 0) {
+		psb_gtt_free_range(dev, r);
+		/* GEM doesn't give an error code and we don't have an
+		   EGEMSUCKS so make something up for now - FIXME */
+		dev_err(dev->dev, "GEM init failed for %lld\n", size);
+		return -ENOMEM;
+	}
+	/* Give the object a handle so we can carry it more easily */
+	ret = drm_gem_handle_create(file, &r->gem, &handle);
+	if (ret) {
+		dev_err(dev->dev, "GEM handle failed for %p, %lld\n",
+							&r->gem, size);
+		drm_gem_object_release(&r->gem);
+		psb_gtt_free_range(dev, r);
+		return ret;
+	}
+	/* We have the initial and handle reference but need only one now */
+	drm_gem_object_unreference(&r->gem);
+	*handlep = handle;
+	return 0;
+}
+
+/**
+ *	psb_gem_dumb_create	-	create a dumb buffer
+ *	@drm_file: our client file
+ *	@dev: our device
+ *	@args: the requested arguments copied from userspace
+ *
+ *	Allocate a buffer suitable for use for a frame buffer of the
+ *	form described by user space. Give userspace a handle by which
+ *	to reference it.
+ */
+int psb_gem_dumb_create(struct drm_file *file, struct drm_device *dev,
+			struct drm_mode_create_dumb *args)
+{
+	args->pitch = ALIGN(args->width * ((args->bpp + 7) / 8), 64);
+	args->size = args->pitch * args->height;
+	return psb_gem_create(file, dev, args->size, &args->handle);
+}
+
+/**
+ *	psb_gem_dumb_destroy	-	destroy a dumb buffer
+ *	@file: client file
+ *	@dev: our DRM device
+ *	@handle: the object handle
+ *
+ *	Destroy a handle that was created via psb_gem_dumb_create, at least
+ *	we hope it was created that way. i915 seems to assume the caller
+ *	does the checking but that might be worth review ! FIXME
+ */
+int psb_gem_dumb_destroy(struct drm_file *file, struct drm_device *dev,
+			uint32_t handle)
+{
+	/* No special work needed, drop the reference and see what falls out */
+	return drm_gem_handle_delete(file, handle);
+}
+
+/**
+ *	psb_gem_fault		-	pagefault handler for GEM objects
+ *	@vma: the VMA of the GEM object
+ *	@vmf: fault detail
+ *
+ *	Invoked when a fault occurs on an mmap of a GEM managed area. GEM
+ *	does most of the work for us including the actual map/unmap calls
+ *	but we need to do the actual page work.
+ *
+ *	This code eventually needs to handle faulting objects in and out
+ *	of the GTT and repacking it when we run out of space. We can put
+ *	that off for now and for our simple uses
+ *
+ *	The VMA was set up by GEM. In doing so it also ensured that the
+ *	vma->vm_private_data points to the GEM object that is backing this
+ *	mapping.
+ *
+ *	FIXME
+ */
+int psb_gem_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
+{
+	struct drm_gem_object *obj;
+	struct gtt_range *r;
+	int ret;
+	unsigned long pfn;
+	pgoff_t page_offset;
+	struct drm_device *dev;
+	struct drm_psb_private *dev_priv;
+
+	obj = vma->vm_private_data;	/* GEM object */
+	dev = obj->dev;
+	dev_priv = dev->dev_private;
+
+	r = container_of(obj, struct gtt_range, gem);	/* Get the gtt range */
+
+	/* Make sure we don't parallel update on a fault, nor move or remove
+	   something from beneath our feet */
+	mutex_lock(&dev->struct_mutex);
+
+	/* For now the mmap pins the object and it stays pinned. As things
+	   stand that will do us no harm */
+	if (r->mmapping == 0) {
+		ret = psb_gtt_pin(r);
+		if (ret < 0) {
+			dev_err(dev->dev, "gma500: pin failed: %d\n", ret);
+			goto fail;
+		}
+		r->mmapping = 1;
+	}
+
+	/* Page relative to the VMA start - we must calculate this ourselves
+	   because vmf->pgoff is the fake GEM offset */
+	page_offset = ((unsigned long) vmf->virtual_address - vma->vm_start)
+				>> PAGE_SHIFT;
+
+	/* CPU view of the page, don't go via the GART for CPU writes */
+	if (r->stolen)
+		pfn = (dev_priv->stolen_base + r->offset) >> PAGE_SHIFT;
+	else
+		pfn = page_to_pfn(r->pages[page_offset]);
+	ret = vm_insert_pfn(vma, (unsigned long)vmf->virtual_address, pfn);
+
+fail:
+	mutex_unlock(&dev->struct_mutex);
+	switch (ret) {
+	case 0:
+	case -ERESTARTSYS:
+	case -EINTR:
+		return VM_FAULT_NOPAGE;
+	case -ENOMEM:
+		return VM_FAULT_OOM;
+	default:
+		return VM_FAULT_SIGBUS;
+	}
+}
+
+static int psb_gem_create_stolen(struct drm_file *file, struct drm_device *dev,
+						int size, u32 *handle)
+{
+	struct gtt_range *gtt = psb_gtt_alloc_range(dev, size, "gem", 1);
+	if (gtt == NULL)
+		return -ENOMEM;
+	if (drm_gem_private_object_init(dev, &gtt->gem, size) != 0)
+		goto free_gtt;
+	if (drm_gem_handle_create(file, &gtt->gem, handle) == 0)
+		return 0;
+free_gtt:
+	psb_gtt_free_range(dev, gtt);
+	return -ENOMEM;
+}
+
+/*
+ *	GEM interfaces for our specific client
+ */
+int psb_gem_create_ioctl(struct drm_device *dev, void *data,
+					struct drm_file *file)
+{
+	struct drm_psb_gem_create *args = data;
+	int ret;
+	if (args->flags & PSB_GEM_CREATE_STOLEN) {
+		ret = psb_gem_create_stolen(file, dev, args->size,
+							&args->handle);
+		if (ret == 0)
+			return 0;
+		/* Fall throguh */
+		args->flags &= ~PSB_GEM_CREATE_STOLEN;
+	}
+	return psb_gem_create(file, dev, args->size, &args->handle);
+}
+
+int psb_gem_mmap_ioctl(struct drm_device *dev, void *data,
+					struct drm_file *file)
+{
+	struct drm_psb_gem_mmap *args = data;
+	return dev->driver->dumb_map_offset(file, dev,
+						args->handle, &args->offset);
+}
+

drivers/gpu/drm/gma500/gem_glue.c

+/**************************************************************************
+ * Copyright (c) 2011, 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.
+ *
+ **************************************************************************/
+
+#include <drm/drmP.h>
+#include <drm/drm.h>
+
+void drm_gem_object_release_wrap(struct drm_gem_object *obj)
+{
+	/* Remove the list map if one is present */
+	if (obj->map_list.map) {
+		struct drm_gem_mm *mm = obj->dev->mm_private;
+		struct drm_map_list *list = &obj->map_list;
+		drm_ht_remove_item(&mm->offset_hash, &list->hash);
+		drm_mm_put_block(list->file_offset_node);
+		kfree(list->map);
+		list->map = NULL;
+	}
+	drm_gem_object_release(obj);
+}
+
+/**
+ *	gem_create_mmap_offset		-	invent an mmap offset
+ *	@obj: our object
+ *
+ *	Standard implementation of offset generation for mmap as is
+ *	duplicated in several drivers. This belongs in GEM.
+ */
+int gem_create_mmap_offset(struct drm_gem_object *obj)
+{
+	struct drm_device *dev = obj->dev;
+	struct drm_gem_mm *mm = dev->mm_private;
+	struct drm_map_list *list;
+	struct drm_local_map *map;
+	int ret;
+
+	list = &obj->map_list;
+	list->map = kzalloc(sizeof(struct drm_map_list), GFP_KERNEL);
+	if (list->map == NULL)
+		return -ENOMEM;
+	map = list->map;
+	map->type = _DRM_GEM;
+	map->size = obj->size;
+	map->handle = obj;
+
+	list->file_offset_node = drm_mm_search_free(&mm->offset_manager,
+					obj->size / PAGE_SIZE, 0, 0);
+	if (!list->file_offset_node) {
+		dev_err(dev->dev, "failed to allocate offset for bo %d\n",
+								obj->name);
+		ret = -ENOSPC;
+		goto free_it;
+	}
+	list->file_offset_node = drm_mm_get_block(list->file_offset_node,
+					obj->size / PAGE_SIZE, 0);
+	if (!list->file_offset_node) {
+		ret = -ENOMEM;
+		goto free_it;
+	}
+	list->hash.key = list->file_offset_node->start;
+	ret = drm_ht_insert_item(&mm->offset_hash, &list->hash);
+	if (ret) {
+		dev_err(dev->dev, "failed to add to map hash\n");
+		goto free_mm;
+	}
+	return 0;
+
+free_mm:
+	drm_mm_put_block(list->file_offset_node);
+free_it:
+	kfree(list->map);
+	list->map = NULL;
+	return ret;
+}

drivers/gpu/drm/gma500/gem_glue.h

+extern void drm_gem_object_release_wrap(struct drm_gem_object *obj);
+extern int gem_create_mmap_offset(struct drm_gem_object *obj);