/*
 * 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"
#include "drm_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
 * and &drm_driver.dumb_map_offset operations (the latter defaults to
 * drm_gem_dumb_map_offset() if not set). Drivers that don't use GEM handles
 * additionally need to implement the &drm_driver.dumb_destroy operation. 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;

        return drm_gem_handle_delete(file_priv, 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);
}