drivers/gpu/drm/exynos/exynos_drm_gem.c - kernel/msm-4.9 - Gitiles

 /* exynos_drm_gem.c
  *
  * Copyright (c) 2011 Samsung Electronics Co., Ltd.
  * Author: Inki Dae <inki.dae@samsung.com>
  *
  * Permission is hereby granted, free of charge, to any person obtaining a
  * copy of this software and associated documentation files (the "Software"),
  * to deal in the Software without restriction, including without limitation
  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
  * and/or sell copies of the Software, and to permit persons to whom the
  * Software is furnished to do so, subject to the following conditions:
  *
  * The above copyright notice and this permission notice (including the next
  * paragraph) shall be included in all copies or substantial portions of the
  * Software.
  *
  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  * VA LINUX SYSTEMS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
  * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
  * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
  * OTHER DEALINGS IN THE SOFTWARE.
  */

 #include "drmP.h"
 #include "drm.h"

 #include <drm/exynos_drm.h>

 #include "exynos_drm_drv.h"
 #include "exynos_drm_gem.h"
 #include "exynos_drm_buf.h"

 static unsigned int convert_to_vm_err_msg(int msg)
 {
 	unsigned int out_msg;

 	switch (msg) {
 	case 0:
 	case -ERESTARTSYS:
 	case -EINTR:
 		out_msg = VM_FAULT_NOPAGE;
 		break;

 	case -ENOMEM:
 		out_msg = VM_FAULT_OOM;
 		break;

 	default:
 		out_msg = VM_FAULT_SIGBUS;
 		break;
 	}

 	return out_msg;
 }

 static unsigned int get_gem_mmap_offset(struct drm_gem_object *obj)
 {
 	DRM_DEBUG_KMS("%s\n", __FILE__);

 	return (unsigned int)obj->map_list.hash.key << PAGE_SHIFT;
 }

 struct exynos_drm_gem_obj *exynos_drm_gem_create(struct drm_file *file_priv,
 		struct drm_device *dev, unsigned int size,
 		unsigned int *handle)
 {
 	struct exynos_drm_gem_obj *exynos_gem_obj;
 	struct exynos_drm_buf_entry *entry;
 	struct drm_gem_object *obj;
 	int ret;

 	DRM_DEBUG_KMS("%s\n", __FILE__);

 	size = roundup(size, PAGE_SIZE);

 	exynos_gem_obj = kzalloc(sizeof(*exynos_gem_obj), GFP_KERNEL);
 	if (!exynos_gem_obj) {
 		DRM_ERROR("failed to allocate exynos gem object.\n");
 		return ERR_PTR(-ENOMEM);
 	}

 	/* allocate the new buffer object and memory region. */
 	entry = exynos_drm_buf_create(dev, size);
 	if (!entry) {
 		kfree(exynos_gem_obj);
 		return ERR_PTR(-ENOMEM);
 	}

 	exynos_gem_obj->entry = entry;

 	obj = &exynos_gem_obj->base;

 	ret = drm_gem_object_init(dev, obj, size);
 	if (ret < 0) {
 		DRM_ERROR("failed to initailize gem object.\n");
 		goto err_obj_init;
 	}

 	DRM_DEBUG_KMS("created file object = 0x%x\n", (unsigned int)obj->filp);

 	ret = drm_gem_create_mmap_offset(obj);
 	if (ret < 0) {
 		DRM_ERROR("failed to allocate mmap offset.\n");
 		goto err_create_mmap_offset;
 	}

 	/*
 	 * allocate a id of idr table where the obj is registered
 	 * and handle has the id what user can see.
 	 */
 	ret = drm_gem_handle_create(file_priv, obj, handle);
 	if (ret)
 		goto err_handle_create;

 	DRM_DEBUG_KMS("gem handle = 0x%x\n", *handle);

 	/* drop reference from allocate - handle holds it now. */
 	drm_gem_object_unreference_unlocked(obj);

 	return exynos_gem_obj;

 err_handle_create:
 	drm_gem_free_mmap_offset(obj);

 err_create_mmap_offset:
 	drm_gem_object_release(obj);

 err_obj_init:
 	exynos_drm_buf_destroy(dev, exynos_gem_obj->entry);

 	kfree(exynos_gem_obj);

 	return ERR_PTR(ret);
 }

 int exynos_drm_gem_create_ioctl(struct drm_device *dev, void *data,
 		struct drm_file *file_priv)
 {
 	struct drm_exynos_gem_create *args = data;
 	struct exynos_drm_gem_obj *exynos_gem_obj;

 	DRM_DEBUG_KMS("%s : size = 0x%x\n", __FILE__, args->size);

 	exynos_gem_obj = exynos_drm_gem_create(file_priv, dev, args->size,
 			&args->handle);
 	if (IS_ERR(exynos_gem_obj))
 		return PTR_ERR(exynos_gem_obj);

 	return 0;
 }

 int exynos_drm_gem_map_offset_ioctl(struct drm_device *dev, void *data,
 		struct drm_file *file_priv)
 {
 	struct drm_exynos_gem_map_off *args = data;

 	DRM_DEBUG_KMS("%s\n", __FILE__);

 	DRM_DEBUG_KMS("handle = 0x%x, offset = 0x%lx\n",
 			args->handle, (unsigned long)args->offset);

 	if (!(dev->driver->driver_features & DRIVER_GEM)) {
 		DRM_ERROR("does not support GEM.\n");
 		return -ENODEV;
 	}

 	return exynos_drm_gem_dumb_map_offset(file_priv, dev, args->handle,
 			&args->offset);
 }

 static int exynos_drm_gem_mmap_buffer(struct file *filp,
 		struct vm_area_struct *vma)
 {
 	struct drm_gem_object *obj = filp->private_data;
 	struct exynos_drm_gem_obj *exynos_gem_obj = to_exynos_gem_obj(obj);
 	struct exynos_drm_buf_entry *entry;
 	unsigned long pfn, vm_size;

 	DRM_DEBUG_KMS("%s\n", __FILE__);

 	vma->vm_flags |= (VM_IO | VM_RESERVED);

 	vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
 	vma->vm_file = filp;

 	vm_size = vma->vm_end - vma->vm_start;
 	/*
 	 * a entry contains information to physically continuous memory
 	 * allocated by user request or at framebuffer creation.
 	 */
 	entry = exynos_gem_obj->entry;

 	/* check if user-requested size is valid. */
 	if (vm_size > entry->size)
 		return -EINVAL;

 	/*
 	 * get page frame number to physical memory to be mapped
 	 * to user space.
 	 */
 	pfn = exynos_gem_obj->entry->paddr >> PAGE_SHIFT;

 	DRM_DEBUG_KMS("pfn = 0x%lx\n", pfn);

 	if (remap_pfn_range(vma, vma->vm_start, pfn, vm_size,
 				vma->vm_page_prot)) {
 		DRM_ERROR("failed to remap pfn range.\n");
 		return -EAGAIN;
 	}

 	return 0;
 }

 static const struct file_operations exynos_drm_gem_fops = {
 	.mmap = exynos_drm_gem_mmap_buffer,
 };

 int exynos_drm_gem_mmap_ioctl(struct drm_device *dev, void *data,
 		struct drm_file *file_priv)
 {
 	struct drm_exynos_gem_mmap *args = data;
 	struct drm_gem_object *obj;
 	unsigned int addr;

 	DRM_DEBUG_KMS("%s\n", __FILE__);

 	if (!(dev->driver->driver_features & DRIVER_GEM)) {
 		DRM_ERROR("does not support GEM.\n");
 		return -ENODEV;
 	}

 	obj = drm_gem_object_lookup(dev, file_priv, args->handle);
 	if (!obj) {
 		DRM_ERROR("failed to lookup gem object.\n");
 		return -EINVAL;
 	}

 	obj->filp->f_op = &exynos_drm_gem_fops;
 	obj->filp->private_data = obj;

 	down_write(&current->mm->mmap_sem);
 	addr = do_mmap(obj->filp, 0, args->size,
 			PROT_READ | PROT_WRITE, MAP_SHARED, 0);
 	up_write(&current->mm->mmap_sem);

 	drm_gem_object_unreference_unlocked(obj);

 	if (IS_ERR((void *)addr))
 		return PTR_ERR((void *)addr);

 	args->mapped = addr;

 	DRM_DEBUG_KMS("mapped = 0x%lx\n", (unsigned long)args->mapped);

 	return 0;
 }

 int exynos_drm_gem_init_object(struct drm_gem_object *obj)
 {
 	DRM_DEBUG_KMS("%s\n", __FILE__);

 	return 0;
 }

 void exynos_drm_gem_free_object(struct drm_gem_object *gem_obj)
 {
 	struct exynos_drm_gem_obj *exynos_gem_obj;

 	DRM_DEBUG_KMS("%s\n", __FILE__);

 	DRM_DEBUG_KMS("handle count = %d\n",
 			atomic_read(&gem_obj->handle_count));

 	if (gem_obj->map_list.map)
 		drm_gem_free_mmap_offset(gem_obj);

 	/* release file pointer to gem object. */
 	drm_gem_object_release(gem_obj);

 	exynos_gem_obj = to_exynos_gem_obj(gem_obj);

 	exynos_drm_buf_destroy(gem_obj->dev, exynos_gem_obj->entry);

 	kfree(exynos_gem_obj);
 }

 int exynos_drm_gem_dumb_create(struct drm_file *file_priv,
 		struct drm_device *dev, struct drm_mode_create_dumb *args)
 {
 	struct exynos_drm_gem_obj *exynos_gem_obj;

 	DRM_DEBUG_KMS("%s\n", __FILE__);

 	/*
 	 * alocate memory to be used for framebuffer.
 	 * - this callback would be called by user application
 	 *	with DRM_IOCTL_MODE_CREATE_DUMB command.
 	 */

 	args->pitch = args->width * args->bpp >> 3;
 	args->size = args->pitch * args->height;

 	exynos_gem_obj = exynos_drm_gem_create(file_priv, dev, args->size,
 							&args->handle);
 	if (IS_ERR(exynos_gem_obj))
 		return PTR_ERR(exynos_gem_obj);

 	return 0;
 }

 int exynos_drm_gem_dumb_map_offset(struct drm_file *file_priv,
 		struct drm_device *dev, uint32_t handle, uint64_t *offset)
 {
 	struct exynos_drm_gem_obj *exynos_gem_obj;
 	struct drm_gem_object *obj;

 	DRM_DEBUG_KMS("%s\n", __FILE__);

 	mutex_lock(&dev->struct_mutex);

 	/*
 	 * get offset of memory allocated for drm framebuffer.
 	 * - this callback would be called by user application
 	 *	with DRM_IOCTL_MODE_MAP_DUMB command.
 	 */

 	obj = drm_gem_object_lookup(dev, file_priv, handle);
 	if (!obj) {
 		DRM_ERROR("failed to lookup gem object.\n");
 		mutex_unlock(&dev->struct_mutex);
 		return -EINVAL;
 	}

 	exynos_gem_obj = to_exynos_gem_obj(obj);

 	*offset = get_gem_mmap_offset(&exynos_gem_obj->base);

 	drm_gem_object_unreference(obj);

 	DRM_DEBUG_KMS("offset = 0x%lx\n", (unsigned long)*offset);

 	mutex_unlock(&dev->struct_mutex);

 	return 0;
 }

 int exynos_drm_gem_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
 {
 	struct drm_gem_object *obj = vma->vm_private_data;
 	struct exynos_drm_gem_obj *exynos_gem_obj = to_exynos_gem_obj(obj);
 	struct drm_device *dev = obj->dev;
 	unsigned long pfn;
 	pgoff_t page_offset;
 	int ret;

 	page_offset = ((unsigned long)vmf->virtual_address -
 			vma->vm_start) >> PAGE_SHIFT;

 	mutex_lock(&dev->struct_mutex);

 	pfn = (exynos_gem_obj->entry->paddr >> PAGE_SHIFT) + page_offset;

 	ret = vm_insert_mixed(vma, (unsigned long)vmf->virtual_address, pfn);

 	mutex_unlock(&dev->struct_mutex);

 	return convert_to_vm_err_msg(ret);
 }

 int exynos_drm_gem_mmap(struct file *filp, struct vm_area_struct *vma)
 {
 	int ret;

 	DRM_DEBUG_KMS("%s\n", __FILE__);

 	/* set vm_area_struct. */
 	ret = drm_gem_mmap(filp, vma);
 	if (ret < 0) {
 		DRM_ERROR("failed to mmap.\n");
 		return ret;
 	}

 	vma->vm_flags &= ~VM_PFNMAP;
 	vma->vm_flags |= VM_MIXEDMAP;

 	return ret;
 }


 int exynos_drm_gem_dumb_destroy(struct drm_file *file_priv,
 		struct drm_device *dev, unsigned int handle)
 {
 	int ret;

 	DRM_DEBUG_KMS("%s\n", __FILE__);

 	/*
 	 * obj->refcount and obj->handle_count are decreased and
 	 * if both them are 0 then exynos_drm_gem_free_object()
 	 * would be called by callback to release resources.
 	 */
 	ret = drm_gem_handle_delete(file_priv, handle);
 	if (ret < 0) {
 		DRM_ERROR("failed to delete drm_gem_handle.\n");
 		return ret;
 	}

 	return 0;
 }

 MODULE_AUTHOR("Inki Dae <inki.dae@samsung.com>");
 MODULE_DESCRIPTION("Samsung SoC DRM GEM Module");
 MODULE_LICENSE("GPL");
	/* exynos_drm_gem.c
	*
	* Copyright (c) 2011 Samsung Electronics Co., Ltd.
	* Author: Inki Dae <inki.dae@samsung.com>
	*
	* Permission is hereby granted, free of charge, to any person obtaining a
	* copy of this software and associated documentation files (the "Software"),
	* to deal in the Software without restriction, including without limitation
	* the rights to use, copy, modify, merge, publish, distribute, sublicense,
	* and/or sell copies of the Software, and to permit persons to whom the
	* Software is furnished to do so, subject to the following conditions:
	*
	* The above copyright notice and this permission notice (including the next
	* paragraph) shall be included in all copies or substantial portions of the
	* Software.
	*
	* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
	* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
	* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
	* VA LINUX SYSTEMS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
	* OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
	* ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
	* OTHER DEALINGS IN THE SOFTWARE.
	*/

	#include "drmP.h"
	#include "drm.h"

	#include <drm/exynos_drm.h>

	#include "exynos_drm_drv.h"
	#include "exynos_drm_gem.h"
	#include "exynos_drm_buf.h"

	static unsigned int convert_to_vm_err_msg(int msg)
	{
	unsigned int out_msg;

	switch (msg) {
	case 0:
	case -ERESTARTSYS:
	case -EINTR:
	out_msg = VM_FAULT_NOPAGE;
	break;

	case -ENOMEM:
	out_msg = VM_FAULT_OOM;
	break;

	default:
	out_msg = VM_FAULT_SIGBUS;
	break;
	}

	return out_msg;
	}

	static unsigned int get_gem_mmap_offset(struct drm_gem_object *obj)
	{
	DRM_DEBUG_KMS("%s\n", __FILE__);

	return (unsigned int)obj->map_list.hash.key << PAGE_SHIFT;
	}

	struct exynos_drm_gem_obj exynos_drm_gem_create(struct drm_file file_priv,
	struct drm_device *dev, unsigned int size,
	unsigned int *handle)
	{
	struct exynos_drm_gem_obj *exynos_gem_obj;
	struct exynos_drm_buf_entry *entry;
	struct drm_gem_object *obj;
	int ret;

	DRM_DEBUG_KMS("%s\n", __FILE__);

	size = roundup(size, PAGE_SIZE);

	exynos_gem_obj = kzalloc(sizeof(*exynos_gem_obj), GFP_KERNEL);
	if (!exynos_gem_obj) {
	DRM_ERROR("failed to allocate exynos gem object.\n");
	return ERR_PTR(-ENOMEM);
	}

	/* allocate the new buffer object and memory region. */
	entry = exynos_drm_buf_create(dev, size);
	if (!entry) {
	kfree(exynos_gem_obj);
	return ERR_PTR(-ENOMEM);
	}

	exynos_gem_obj->entry = entry;

	obj = &exynos_gem_obj->base;

	ret = drm_gem_object_init(dev, obj, size);
	if (ret < 0) {
	DRM_ERROR("failed to initailize gem object.\n");
	goto err_obj_init;
	}

	DRM_DEBUG_KMS("created file object = 0x%x\n", (unsigned int)obj->filp);

	ret = drm_gem_create_mmap_offset(obj);
	if (ret < 0) {
	DRM_ERROR("failed to allocate mmap offset.\n");
	goto err_create_mmap_offset;
	}

	/*
	* allocate a id of idr table where the obj is registered
	* and handle has the id what user can see.
	*/
	ret = drm_gem_handle_create(file_priv, obj, handle);
	if (ret)
	goto err_handle_create;

	DRM_DEBUG_KMS("gem handle = 0x%x\n", *handle);

	/* drop reference from allocate - handle holds it now. */
	drm_gem_object_unreference_unlocked(obj);

	return exynos_gem_obj;

	err_handle_create:
	drm_gem_free_mmap_offset(obj);

	err_create_mmap_offset:
	drm_gem_object_release(obj);

	err_obj_init:
	exynos_drm_buf_destroy(dev, exynos_gem_obj->entry);

	kfree(exynos_gem_obj);

	return ERR_PTR(ret);
	}

	int exynos_drm_gem_create_ioctl(struct drm_device dev, void data,
	struct drm_file *file_priv)
	{
	struct drm_exynos_gem_create *args = data;
	struct exynos_drm_gem_obj *exynos_gem_obj;

	DRM_DEBUG_KMS("%s : size = 0x%x\n", __FILE__, args->size);

	exynos_gem_obj = exynos_drm_gem_create(file_priv, dev, args->size,
	&args->handle);
	if (IS_ERR(exynos_gem_obj))
	return PTR_ERR(exynos_gem_obj);

	return 0;
	}

	int exynos_drm_gem_map_offset_ioctl(struct drm_device dev, void data,
	struct drm_file *file_priv)
	{
	struct drm_exynos_gem_map_off *args = data;

	DRM_DEBUG_KMS("%s\n", __FILE__);

	DRM_DEBUG_KMS("handle = 0x%x, offset = 0x%lx\n",
	args->handle, (unsigned long)args->offset);

	if (!(dev->driver->driver_features & DRIVER_GEM)) {
	DRM_ERROR("does not support GEM.\n");
	return -ENODEV;
	}

	return exynos_drm_gem_dumb_map_offset(file_priv, dev, args->handle,
	&args->offset);
	}

	static int exynos_drm_gem_mmap_buffer(struct file *filp,
	struct vm_area_struct *vma)
	{
	struct drm_gem_object *obj = filp->private_data;
	struct exynos_drm_gem_obj *exynos_gem_obj = to_exynos_gem_obj(obj);
	struct exynos_drm_buf_entry *entry;
	unsigned long pfn, vm_size;

	DRM_DEBUG_KMS("%s\n", __FILE__);

	vma->vm_flags \|= (VM_IO \| VM_RESERVED);

	vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
	vma->vm_file = filp;

	vm_size = vma->vm_end - vma->vm_start;
	/*
	* a entry contains information to physically continuous memory
	* allocated by user request or at framebuffer creation.
	*/
	entry = exynos_gem_obj->entry;

	/* check if user-requested size is valid. */
	if (vm_size > entry->size)
	return -EINVAL;

	/*
	* get page frame number to physical memory to be mapped
	* to user space.
	*/
	pfn = exynos_gem_obj->entry->paddr >> PAGE_SHIFT;

	DRM_DEBUG_KMS("pfn = 0x%lx\n", pfn);

	if (remap_pfn_range(vma, vma->vm_start, pfn, vm_size,
	vma->vm_page_prot)) {
	DRM_ERROR("failed to remap pfn range.\n");
	return -EAGAIN;
	}

	return 0;
	}

	static const struct file_operations exynos_drm_gem_fops = {
	.mmap = exynos_drm_gem_mmap_buffer,
	};

	int exynos_drm_gem_mmap_ioctl(struct drm_device dev, void data,
	struct drm_file *file_priv)
	{
	struct drm_exynos_gem_mmap *args = data;
	struct drm_gem_object *obj;
	unsigned int addr;

	DRM_DEBUG_KMS("%s\n", __FILE__);

	if (!(dev->driver->driver_features & DRIVER_GEM)) {
	DRM_ERROR("does not support GEM.\n");
	return -ENODEV;
	}

	obj = drm_gem_object_lookup(dev, file_priv, args->handle);
	if (!obj) {
	DRM_ERROR("failed to lookup gem object.\n");
	return -EINVAL;
	}

	obj->filp->f_op = &exynos_drm_gem_fops;
	obj->filp->private_data = obj;

	down_write(&current->mm->mmap_sem);
	addr = do_mmap(obj->filp, 0, args->size,
	PROT_READ \| PROT_WRITE, MAP_SHARED, 0);
	up_write(&current->mm->mmap_sem);

	drm_gem_object_unreference_unlocked(obj);

	if (IS_ERR((void *)addr))
	return PTR_ERR((void *)addr);

	args->mapped = addr;

	DRM_DEBUG_KMS("mapped = 0x%lx\n", (unsigned long)args->mapped);

	return 0;
	}

	int exynos_drm_gem_init_object(struct drm_gem_object *obj)
	{
	DRM_DEBUG_KMS("%s\n", __FILE__);

	return 0;
	}

	void exynos_drm_gem_free_object(struct drm_gem_object *gem_obj)
	{
	struct exynos_drm_gem_obj *exynos_gem_obj;

	DRM_DEBUG_KMS("%s\n", __FILE__);

	DRM_DEBUG_KMS("handle count = %d\n",
	atomic_read(&gem_obj->handle_count));

	if (gem_obj->map_list.map)
	drm_gem_free_mmap_offset(gem_obj);

	/* release file pointer to gem object. */
	drm_gem_object_release(gem_obj);

	exynos_gem_obj = to_exynos_gem_obj(gem_obj);

	exynos_drm_buf_destroy(gem_obj->dev, exynos_gem_obj->entry);

	kfree(exynos_gem_obj);
	}

	int exynos_drm_gem_dumb_create(struct drm_file *file_priv,
	struct drm_device dev, struct drm_mode_create_dumb args)
	{
	struct exynos_drm_gem_obj *exynos_gem_obj;

	DRM_DEBUG_KMS("%s\n", __FILE__);

	/*
	* alocate memory to be used for framebuffer.
	* - this callback would be called by user application
	* with DRM_IOCTL_MODE_CREATE_DUMB command.
	*/

	args->pitch = args->width * args->bpp >> 3;
	args->size = args->pitch * args->height;

	exynos_gem_obj = exynos_drm_gem_create(file_priv, dev, args->size,
	&args->handle);
	if (IS_ERR(exynos_gem_obj))
	return PTR_ERR(exynos_gem_obj);

	return 0;
	}

	int exynos_drm_gem_dumb_map_offset(struct drm_file *file_priv,
	struct drm_device dev, uint32_t handle, uint64_t offset)
	{
	struct exynos_drm_gem_obj *exynos_gem_obj;
	struct drm_gem_object *obj;

	DRM_DEBUG_KMS("%s\n", __FILE__);

	mutex_lock(&dev->struct_mutex);

	/*
	* get offset of memory allocated for drm framebuffer.
	* - this callback would be called by user application
	* with DRM_IOCTL_MODE_MAP_DUMB command.
	*/

	obj = drm_gem_object_lookup(dev, file_priv, handle);
	if (!obj) {
	DRM_ERROR("failed to lookup gem object.\n");
	mutex_unlock(&dev->struct_mutex);
	return -EINVAL;
	}

	exynos_gem_obj = to_exynos_gem_obj(obj);

	*offset = get_gem_mmap_offset(&exynos_gem_obj->base);

	drm_gem_object_unreference(obj);

	DRM_DEBUG_KMS("offset = 0x%lx\n", (unsigned long)*offset);

	mutex_unlock(&dev->struct_mutex);

	return 0;
	}

	int exynos_drm_gem_fault(struct vm_area_struct vma, struct vm_fault vmf)
	{
	struct drm_gem_object *obj = vma->vm_private_data;
	struct exynos_drm_gem_obj *exynos_gem_obj = to_exynos_gem_obj(obj);
	struct drm_device *dev = obj->dev;
	unsigned long pfn;
	pgoff_t page_offset;
	int ret;

	page_offset = ((unsigned long)vmf->virtual_address -
	vma->vm_start) >> PAGE_SHIFT;

	mutex_lock(&dev->struct_mutex);

	pfn = (exynos_gem_obj->entry->paddr >> PAGE_SHIFT) + page_offset;

	ret = vm_insert_mixed(vma, (unsigned long)vmf->virtual_address, pfn);

	mutex_unlock(&dev->struct_mutex);

	return convert_to_vm_err_msg(ret);
	}

	int exynos_drm_gem_mmap(struct file filp, struct vm_area_struct vma)
	{
	int ret;

	DRM_DEBUG_KMS("%s\n", __FILE__);

	/* set vm_area_struct. */
	ret = drm_gem_mmap(filp, vma);
	if (ret < 0) {
	DRM_ERROR("failed to mmap.\n");
	return ret;
	}

	vma->vm_flags &= ~VM_PFNMAP;
	vma->vm_flags \|= VM_MIXEDMAP;

	return ret;
	}


	int exynos_drm_gem_dumb_destroy(struct drm_file *file_priv,
	struct drm_device *dev, unsigned int handle)
	{
	int ret;

	DRM_DEBUG_KMS("%s\n", __FILE__);

	/*
	* obj->refcount and obj->handle_count are decreased and
	* if both them are 0 then exynos_drm_gem_free_object()
	* would be called by callback to release resources.
	*/
	ret = drm_gem_handle_delete(file_priv, handle);
	if (ret < 0) {
	DRM_ERROR("failed to delete drm_gem_handle.\n");
	return ret;
	}

	return 0;
	}

	MODULE_AUTHOR("Inki Dae <inki.dae@samsung.com>");
	MODULE_DESCRIPTION("Samsung SoC DRM GEM Module");
	MODULE_LICENSE("GPL");