text: /*
   * Copyright (c) 2006-2008 Intel Corporation
   * Copyright (c) 2007 Dave Airlie <airlied@linux.ie>
   * Copyright (c) 2008 Red Hat Inc.
   * Copyright (c) 2016 Intel Corporation
   *
   * Permission to use, copy, modify, distribute, and sell this software and its
   * documentation for any purpose is hereby granted without fee, provided that
   * the above copyright notice appear in all copies and that both that copyright
   * notice and this permission notice appear in supporting documentation, and
   * that the name of the copyright holders not be used in advertising or
   * publicity pertaining to distribution of the software without specific,
   * written prior permission.  The copyright holders make no representations
   * about the suitability of this software for any purpose.  It is provided "as
   * is" without express or implied warranty.
   *
   * THE COPYRIGHT HOLDERS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
   * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
   * EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY SPECIAL, INDIRECT OR
   * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE,
   * DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
   * TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
   * OF THIS SOFTWARE.
   */
  
  #include <drm/drm_device.h>
  #include <drm/drm_drv.h>
  #include <drm/drm_gem.h>
  #include <drm/drm_mode.h>
  
  #include "drm_crtc_internal.h"
  
  /**
   * DOC: overview
   *
   * The KMS API doesn't standardize backing storage object creation and leaves it
   * to driver-specific ioctls. Furthermore actually creating a buffer object even
   * for GEM-based drivers is done through a driver-specific ioctl - GEM only has
   * a common userspace interface for sharing and destroying objects. While not an
   * issue for full-fledged graphics stacks that include device-specific userspace
   * components (in libdrm for instance), this limit makes DRM-based early boot
   * graphics unnecessarily complex.
   *
   * Dumb objects partly alleviate the problem by providing a standard API to
   * create dumb buffers suitable for scanout, which can then be used to create
   * KMS frame buffers.
   *
   * To support dumb objects drivers must implement the &drm_driver.dumb_create
   * operation. &drm_driver.dumb_destroy defaults to drm_gem_dumb_destroy() if
   * not set and &drm_driver.dumb_map_offset defaults to
   * drm_gem_dumb_map_offset(). See the callbacks for further details.
   *
   * Note that dumb objects may not be used for gpu acceleration, as has been
   * attempted on some ARM embedded platforms. Such drivers really must have
   * a hardware-specific ioctl to allocate suitable buffer objects.
   */
  
  int drm_mode_create_dumb(struct drm_device *dev,
  			 struct drm_mode_create_dumb *args,
  			 struct drm_file *file_priv)
  {
  	u32 cpp, stride, size;
  
  	if (!dev->driver->dumb_create)
  		return -ENOSYS;
  	if (!args->width || !args->height || !args->bpp)
  		return -EINVAL;
  
  	/* overflow checks for 32bit size calculations */
  	if (args->bpp > U32_MAX - 8)
  		return -EINVAL;
  	cpp = DIV_ROUND_UP(args->bpp, 8);
  	if (cpp > U32_MAX / args->width)
  		return -EINVAL;
  	stride = cpp * args->width;
  	if (args->height > U32_MAX / stride)
  		return -EINVAL;
  
  	/* test for wrap-around */
  	size = args->height * stride;
  	if (PAGE_ALIGN(size) == 0)
  		return -EINVAL;
  
  	/*
  	 * handle, pitch and size are output parameters. Zero them out to
  	 * prevent drivers from accidentally using uninitialized data. Since
  	 * not all existing userspace is clearing these fields properly we
  	 * cannot reject IOCTL with garbage in them.
  	 */
  	args->handle = 0;
  	args->pitch = 0;
  	args->size = 0;
  
  	return dev->driver->dumb_create(file_priv, dev, args);
  }
  
  int drm_mode_create_dumb_ioctl(struct drm_device *dev,
  			       void *data, struct drm_file *file_priv)
  {
  	return drm_mode_create_dumb(dev, data, file_priv);
  }
  
  /**
   * drm_mode_mmap_dumb_ioctl - create an mmap offset for a dumb backing storage buffer
   * @dev: DRM device
   * @data: ioctl data
   * @file_priv: DRM file info
   *
   * Allocate an offset in the drm device node's address space to be able to
   * memory map a dumb buffer.
   *
   * Called by the user via ioctl.
   *
   * Returns:
   * Zero on success, negative errno on failure.
   */
  int drm_mode_mmap_dumb_ioctl(struct drm_device *dev,
  			     void *data, struct drm_file *file_priv)
  {
  	struct drm_mode_map_dumb *args = data;
  
  	if (!dev->driver->dumb_create)
  		return -ENOSYS;
  
  	if (dev->driver->dumb_map_offset)
  		return dev->driver->dumb_map_offset(file_priv, dev,
  						    args->handle,
  						    &args->offset);
  	else
  		return drm_gem_dumb_map_offset(file_priv, dev, args->handle,
  					       &args->offset);
  }
  
  int drm_mode_destroy_dumb(struct drm_device *dev, u32 handle,
  			  struct drm_file *file_priv)
  {
  	if (!dev->driver->dumb_create)
  		return -ENOSYS;
  
  	if (dev->driver->dumb_destroy)
  		return dev->driver->dumb_destroy(file_priv, dev, handle);
  	else
  		return drm_gem_dumb_destroy(file_priv, dev, handle);
  }
  
  int drm_mode_destroy_dumb_ioctl(struct drm_device *dev,
  				void *data, struct drm_file *file_priv)
  {
  	struct drm_mode_destroy_dumb *args = data;
  
  	return drm_mode_destroy_dumb(dev, args->handle, file_priv);
  }
  