xref: /netbsd/src/sys/external/bsd/drm2/dist/drm/drm_prime.c

/*        $NetBSD: drm_prime.c,v 1.20 2022/07/06 01:12:45 riastradh Exp $       */

/*
 * Copyright © 2012 Red Hat
 *
 * 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
 * THE AUTHORS OR COPYRIGHT HOLDERS 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.
 *
 * Authors:
 *      Dave Airlie <airlied@redhat.com>
 *      Rob Clark <rob.clark@linaro.org>
 *
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: drm_prime.c,v 1.20 2022/07/06 01:12:45 riastradh Exp $");

#include <linux/export.h>
#include <linux/dma-buf.h>
#include <linux/rbtree.h>

#include <drm/drm.h>
#include <drm/drm_drv.h>
#include <drm/drm_file.h>
#include <drm/drm_framebuffer.h>
#include <drm/drm_gem.h>
#include <drm/drm_prime.h>

#include "drm_internal.h"

#ifdef __NetBSD__

#include <sys/file.h>

#include <drm/bus_dma_hacks.h>

#include <linux/nbsd-namespace.h>

#endif    /* __NetBSD__ */

/**
 * DOC: overview and lifetime rules
 *
 * Similar to GEM global names, PRIME file descriptors are also used to share
 * buffer objects across processes. They offer additional security: as file
 * descriptors must be explicitly sent over UNIX domain sockets to be shared
 * between applications, they can't be guessed like the globally unique GEM
 * names.
 *
 * Drivers that support the PRIME API implement the
 * &drm_driver.prime_handle_to_fd and &drm_driver.prime_fd_to_handle operations.
 * GEM based drivers must use drm_gem_prime_handle_to_fd() and
 * drm_gem_prime_fd_to_handle() to implement these. For GEM based drivers the
 * actual driver interfaces is provided through the &drm_gem_object_funcs.export
 * and &drm_driver.gem_prime_import hooks.
 *
 * &dma_buf_ops implementations for GEM drivers are all individually exported
 * for drivers which need to overwrite or reimplement some of them.
 *
 * Reference Counting for GEM Drivers
 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 *
 * On the export the &dma_buf holds a reference to the exported buffer object,
 * usually a &drm_gem_object. It takes this reference in the PRIME_HANDLE_TO_FD
 * IOCTL, when it first calls &drm_gem_object_funcs.export
 * and stores the exporting GEM object in the &dma_buf.priv field. This
 * reference needs to be released when the final reference to the &dma_buf
 * itself is dropped and its &dma_buf_ops.release function is called.  For
 * GEM-based drivers, the &dma_buf should be exported using
 * drm_gem_dmabuf_export() and then released by drm_gem_dmabuf_release().
 *
 * Thus the chain of references always flows in one direction, avoiding loops:
 * importing GEM object -> dma-buf -> exported GEM bo. A further complication
 * are the lookup caches for import and export. These are required to guarantee
 * that any given object will always have only one uniqe userspace handle. This
 * is required to allow userspace to detect duplicated imports, since some GEM
 * drivers do fail command submissions if a given buffer object is listed more
 * than once. These import and export caches in &drm_prime_file_private only
 * retain a weak reference, which is cleaned up when the corresponding object is
 * released.
 *
 * Self-importing: If userspace is using PRIME as a replacement for flink then
 * it will get a fd->handle request for a GEM object that it created.  Drivers
 * should detect this situation and return back the underlying object from the
 * dma-buf private. For GEM based drivers this is handled in
 * drm_gem_prime_import() already.
 */

struct drm_prime_member {
          struct dma_buf *dma_buf;
          uint32_t handle;

          struct rb_node dmabuf_rb;
          struct rb_node handle_rb;
};

#ifdef __NetBSD__
static int
compare_dmabufs(void *cookie, const void *va, const void *vb)
{
          const struct drm_prime_member *ma = va;
          const struct drm_prime_member *mb = vb;

          if (ma->dma_buf < mb->dma_buf)
                    return -1;
          if (ma->dma_buf > mb->dma_buf)
                    return +1;
          return 0;
}

static int
compare_dmabuf_key(void *cookie, const void *vm, const void *vk)
{
          const struct drm_prime_member *m = vm;
          const struct dma_buf *const *kp = vk;

          if (m->dma_buf < *kp)
                    return -1;
          if (m->dma_buf > *kp)
                    return +1;
          return 0;
}

static int
compare_handles(void *cookie, const void *va, const void *vb)
{
          const struct drm_prime_member *ma = va;
          const struct drm_prime_member *mb = vb;

          if (ma->handle < mb->handle)
                    return -1;
          if (ma->handle > mb->handle)
                    return +1;
          return 0;
}

static int
compare_handle_key(void *cookie, const void *vm, const void *vk)
{
          const struct drm_prime_member *m = vm;
          const uint32_t *kp = vk;

          if (m->handle < *kp)
                    return -1;
          if (m->handle > *kp)
                    return +1;
          return 0;
}

static const rb_tree_ops_t dmabuf_ops = {
          .rbto_compare_nodes = compare_dmabufs,
          .rbto_compare_key = compare_dmabuf_key,
          .rbto_node_offset = offsetof(struct drm_prime_member, dmabuf_rb),
};

static const rb_tree_ops_t handle_ops = {
          .rbto_compare_nodes = compare_handles,
          .rbto_compare_key = compare_handle_key,
          .rbto_node_offset = offsetof(struct drm_prime_member, handle_rb),
};
#endif

static int drm_prime_add_buf_handle(struct drm_prime_file_private *prime_fpriv,
                                            struct dma_buf *dma_buf, uint32_t handle)
{
          struct drm_prime_member *member;
#ifdef __NetBSD__
          struct drm_prime_member *collision __diagused;
#else
          struct rb_node **p, *rb;
#endif

          member = kmalloc(sizeof(*member), GFP_KERNEL);
          if (!member)
                    return -ENOMEM;

          get_dma_buf(dma_buf);
          member->dma_buf = dma_buf;
          member->handle = handle;

#ifdef __NetBSD__
          collision = rb_tree_insert_node(&prime_fpriv->dmabufs.rbr_tree,
              member);
          KASSERT(collision == member);
#else
          rb = NULL;
          p = &prime_fpriv->dmabufs.rb_node;
          while (*p) {
                    struct drm_prime_member *pos;

                    rb = *p;
                    pos = rb_entry(rb, struct drm_prime_member, dmabuf_rb);
                    if (dma_buf > pos->dma_buf)
                              p = &rb->rb_right;
                    else
                              p = &rb->rb_left;
          }
          rb_link_node(&member->dmabuf_rb, rb, p);
          rb_insert_color(&member->dmabuf_rb, &prime_fpriv->dmabufs);
#endif

#ifdef __NetBSD__
          collision = rb_tree_insert_node(&prime_fpriv->handles.rbr_tree,
              member);
          KASSERT(collision == member);
#else
          rb = NULL;
          p = &prime_fpriv->handles.rb_node;
          while (*p) {
                    struct drm_prime_member *pos;

                    rb = *p;
                    pos = rb_entry(rb, struct drm_prime_member, handle_rb);
                    if (handle > pos->handle)
                              p = &rb->rb_right;
                    else
                              p = &rb->rb_left;
          }
          rb_link_node(&member->handle_rb, rb, p);
          rb_insert_color(&member->handle_rb, &prime_fpriv->handles);
#endif

          return 0;
}

static struct dma_buf *drm_prime_lookup_buf_by_handle(struct drm_prime_file_private *prime_fpriv,
                                                                  uint32_t handle)
{
#ifdef __NetBSD__
          struct drm_prime_member *member;

          member = rb_tree_find_node(&prime_fpriv->handles.rbr_tree, &handle);
          if (member == NULL)
                    return NULL;
          return member->dma_buf;
#else
          struct rb_node *rb;

          rb = prime_fpriv->handles.rb_node;
          while (rb) {
                    struct drm_prime_member *member;

                    member = rb_entry(rb, struct drm_prime_member, handle_rb);
                    if (member->handle == handle)
                              return member->dma_buf;
                    else if (member->handle < handle)
                              rb = rb->rb_right;
                    else
                              rb = rb->rb_left;
          }

          return NULL;
#endif
}

static int drm_prime_lookup_buf_handle(struct drm_prime_file_private *prime_fpriv,
                                               struct dma_buf *dma_buf,
                                               uint32_t *handle)
{
#ifdef __NetBSD__
          struct drm_prime_member *member;

          member = rb_tree_find_node(&prime_fpriv->dmabufs.rbr_tree, &dma_buf);
          if (member == NULL)
                    return -ENOENT;
          *handle = member->handle;
          return 0;
#else
          struct rb_node *rb;

          rb = prime_fpriv->dmabufs.rb_node;
          while (rb) {
                    struct drm_prime_member *member;

                    member = rb_entry(rb, struct drm_prime_member, dmabuf_rb);
                    if (member->dma_buf == dma_buf) {
                              *handle = member->handle;
                              return 0;
                    } else if (member->dma_buf < dma_buf) {
                              rb = rb->rb_right;
                    } else {
                              rb = rb->rb_left;
                    }
          }

          return -ENOENT;
#endif
}

void drm_prime_remove_buf_handle_locked(struct drm_prime_file_private *prime_fpriv,
                                                  struct dma_buf *dma_buf)
{
#ifdef __NetBSD__
          struct drm_prime_member *member;

          member = rb_tree_find_node(&prime_fpriv->dmabufs.rbr_tree, &dma_buf);
          if (member != NULL) {
                    rb_tree_remove_node(&prime_fpriv->handles.rbr_tree, member);
                    rb_tree_remove_node(&prime_fpriv->dmabufs.rbr_tree, member);
                    dma_buf_put(dma_buf);
                    kfree(member);
          }
#else
          struct rb_node *rb;

          rb = prime_fpriv->dmabufs.rb_node;
          while (rb) {
                    struct drm_prime_member *member;

                    member = rb_entry(rb, struct drm_prime_member, dmabuf_rb);
                    if (member->dma_buf == dma_buf) {
                              rb_erase(&member->handle_rb, &prime_fpriv->handles);
                              rb_erase(&member->dmabuf_rb, &prime_fpriv->dmabufs);

                              dma_buf_put(dma_buf);
                              kfree(member);
                              return;
                    } else if (member->dma_buf < dma_buf) {
                              rb = rb->rb_right;
                    } else {
                              rb = rb->rb_left;
                    }
          }
#endif
}

void drm_prime_init_file_private(struct drm_prime_file_private *prime_fpriv)
{
          mutex_init(&prime_fpriv->lock);
#ifdef __NetBSD__
          rb_tree_init(&prime_fpriv->dmabufs.rbr_tree, &dmabuf_ops);
          rb_tree_init(&prime_fpriv->handles.rbr_tree, &handle_ops);
#else
          prime_fpriv->dmabufs = RB_ROOT;
          prime_fpriv->handles = RB_ROOT;
#endif
}

void drm_prime_destroy_file_private(struct drm_prime_file_private *prime_fpriv)
{
          mutex_destroy(&prime_fpriv->lock);
          /* by now drm_gem_release should've made sure the list is empty */
          WARN_ON(!RB_EMPTY_ROOT(&prime_fpriv->dmabufs));
          WARN_ON(!RB_EMPTY_ROOT(&prime_fpriv->handles));
}

/**
 * drm_gem_dmabuf_export - &dma_buf export implementation for GEM
 * @dev: parent device for the exported dmabuf
 * @exp_info: the export information used by dma_buf_export()
 *
 * This wraps dma_buf_export() for use by generic GEM drivers that are using
 * drm_gem_dmabuf_release(). In addition to calling dma_buf_export(), we take
 * a reference to the &drm_device and the exported &drm_gem_object (stored in
 * &dma_buf_export_info.priv) which is released by drm_gem_dmabuf_release().
 *
 * Returns the new dmabuf.
 */
struct dma_buf *drm_gem_dmabuf_export(struct drm_device *dev,
                                              struct dma_buf_export_info *exp_info)
{
          struct drm_gem_object *obj = exp_info->priv;
          struct dma_buf *dma_buf;

          dma_buf = dma_buf_export(exp_info);
          if (IS_ERR(dma_buf))
                    return dma_buf;

          drm_dev_get(dev);
          drm_gem_object_get(obj);
#ifndef __NetBSD__            /* XXX dmabuf share */
          dma_buf->file->f_mapping = obj->dev->anon_inode->i_mapping;
#endif

          return dma_buf;
}
EXPORT_SYMBOL(drm_gem_dmabuf_export);

/**
 * drm_gem_dmabuf_release - &dma_buf release implementation for GEM
 * @dma_buf: buffer to be released
 *
 * Generic release function for dma_bufs exported as PRIME buffers. GEM drivers
 * must use this in their &dma_buf_ops structure as the release callback.
 * drm_gem_dmabuf_release() should be used in conjunction with
 * drm_gem_dmabuf_export().
 */
void drm_gem_dmabuf_release(struct dma_buf *dma_buf)
{
          struct drm_gem_object *obj = dma_buf->priv;
          struct drm_device *dev = obj->dev;

          /* drop the reference on the export fd holds */
          drm_gem_object_put_unlocked(obj);

          drm_dev_put(dev);
}
EXPORT_SYMBOL(drm_gem_dmabuf_release);

/**
 * drm_gem_prime_fd_to_handle - PRIME import function for GEM drivers
 * @dev: dev to export the buffer from
 * @file_priv: drm file-private structure
 * @prime_fd: fd id of the dma-buf which should be imported
 * @handle: pointer to storage for the handle of the imported buffer object
 *
 * This is the PRIME import function which must be used mandatorily by GEM
 * drivers to ensure correct lifetime management of the underlying GEM object.
 * The actual importing of GEM object from the dma-buf is done through the
 * &drm_driver.gem_prime_import driver callback.
 *
 * Returns 0 on success or a negative error code on failure.
 */
int drm_gem_prime_fd_to_handle(struct drm_device *dev,
                                     struct drm_file *file_priv, int prime_fd,
                                     uint32_t *handle)
{
          struct dma_buf *dma_buf;
          struct drm_gem_object *obj;
          int ret;

          dma_buf = dma_buf_get(prime_fd);
          if (IS_ERR(dma_buf))
                    return PTR_ERR(dma_buf);

          mutex_lock(&file_priv->prime.lock);

          ret = drm_prime_lookup_buf_handle(&file_priv->prime,
                              dma_buf, handle);
          if (ret == 0)
                    goto out_put;

          /* never seen this one, need to import */
          mutex_lock(&dev->object_name_lock);
          if (dev->driver->gem_prime_import)
                    obj = dev->driver->gem_prime_import(dev, dma_buf);
          else
                    obj = drm_gem_prime_import(dev, dma_buf);
          if (IS_ERR(obj)) {
                    ret = PTR_ERR(obj);
                    goto out_unlock;
          }

          if (obj->dma_buf) {
                    WARN_ON(obj->dma_buf != dma_buf);
          } else {
                    obj->dma_buf = dma_buf;
                    get_dma_buf(dma_buf);
          }

          /* _handle_create_tail unconditionally unlocks dev->object_name_lock. */
          ret = drm_gem_handle_create_tail(file_priv, obj, handle);
          drm_gem_object_put_unlocked(obj);
          if (ret)
                    goto out_put;

          ret = drm_prime_add_buf_handle(&file_priv->prime,
                              dma_buf, *handle);
          mutex_unlock(&file_priv->prime.lock);
          if (ret)
                    goto fail;

          dma_buf_put(dma_buf);

          return 0;

fail:
          /* hmm, if driver attached, we are relying on the free-object path
           * to detach.. which seems ok..
           */
          drm_gem_handle_delete(file_priv, *handle);
          dma_buf_put(dma_buf);
          return ret;

out_unlock:
          mutex_unlock(&dev->object_name_lock);
out_put:
          mutex_unlock(&file_priv->prime.lock);
          dma_buf_put(dma_buf);
          return ret;
}
EXPORT_SYMBOL(drm_gem_prime_fd_to_handle);

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

          if (!dev->driver->prime_fd_to_handle)
                    return -ENOSYS;

          return dev->driver->prime_fd_to_handle(dev, file_priv,
                              args->fd, &args->handle);
}

static struct dma_buf *export_and_register_object(struct drm_device *dev,
                                                              struct drm_gem_object *obj,
                                                              uint32_t flags)
{
          struct dma_buf *dmabuf;

          /* prevent races with concurrent gem_close. */
          if (obj->handle_count == 0) {
                    dmabuf = ERR_PTR(-ENOENT);
                    return dmabuf;
          }

          if (obj->funcs && obj->funcs->export)
                    dmabuf = obj->funcs->export(obj, flags);
          else if (dev->driver->gem_prime_export)
                    dmabuf = dev->driver->gem_prime_export(obj, flags);
          else
                    dmabuf = drm_gem_prime_export(obj, flags);
          if (IS_ERR(dmabuf)) {
                    /* normally the created dma-buf takes ownership of the ref,
                     * but if that fails then drop the ref
                     */
                    return dmabuf;
          }

          /*
           * Note that callers do not need to clean up the export cache
           * since the check for obj->handle_count guarantees that someone
           * will clean it up.
           */
          obj->dma_buf = dmabuf;
          get_dma_buf(obj->dma_buf);

          return dmabuf;
}

/**
 * drm_gem_prime_handle_to_fd - PRIME export function for GEM drivers
 * @dev: dev to export the buffer from
 * @file_priv: drm file-private structure
 * @handle: buffer handle to export
 * @flags: flags like DRM_CLOEXEC
 * @prime_fd: pointer to storage for the fd id of the create dma-buf
 *
 * This is the PRIME export function which must be used mandatorily by GEM
 * drivers to ensure correct lifetime management of the underlying GEM object.
 * The actual exporting from GEM object to a dma-buf is done through the
 * &drm_driver.gem_prime_export driver callback.
 */
int drm_gem_prime_handle_to_fd(struct drm_device *dev,
                                     struct drm_file *file_priv, uint32_t handle,
                                     uint32_t flags,
                                     int *prime_fd)
{
          struct drm_gem_object *obj;
          int ret = 0;
          struct dma_buf *dmabuf;

          mutex_lock(&file_priv->prime.lock);
          obj = drm_gem_object_lookup(file_priv, handle);
          if (!obj)  {
                    ret = -ENOENT;
                    goto out_unlock;
          }

          dmabuf = drm_prime_lookup_buf_by_handle(&file_priv->prime, handle);
          if (dmabuf) {
                    get_dma_buf(dmabuf);
                    goto out_have_handle;
          }

          mutex_lock(&dev->object_name_lock);
          /* re-export the original imported object */
          if (obj->import_attach) {
                    dmabuf = obj->import_attach->dmabuf;
                    get_dma_buf(dmabuf);
                    goto out_have_obj;
          }

          if (obj->dma_buf) {
                    get_dma_buf(obj->dma_buf);
                    dmabuf = obj->dma_buf;
                    goto out_have_obj;
          }

          dmabuf = export_and_register_object(dev, obj, flags);
          if (IS_ERR(dmabuf)) {
                    /* normally the created dma-buf takes ownership of the ref,
                     * but if that fails then drop the ref
                     */
                    ret = PTR_ERR(dmabuf);
                    mutex_unlock(&dev->object_name_lock);
                    goto out;
          }

out_have_obj:
          /*
           * If we've exported this buffer then cheat and add it to the import list
           * so we get the correct handle back. We must do this under the
           * protection of dev->object_name_lock to ensure that a racing gem close
           * ioctl doesn't miss to remove this buffer handle from the cache.
           */
          ret = drm_prime_add_buf_handle(&file_priv->prime,
                                               dmabuf, handle);
          mutex_unlock(&dev->object_name_lock);
          if (ret)
                    goto fail_put_dmabuf;

out_have_handle:
          ret = dma_buf_fd(dmabuf, flags);
          /*
           * We must _not_ remove the buffer from the handle cache since the newly
           * created dma buf is already linked in the global obj->dma_buf pointer,
           * and that is invariant as long as a userspace gem handle exists.
           * Closing the handle will clean out the cache anyway, so we don't leak.
           */
          if (ret < 0) {
                    goto fail_put_dmabuf;
          } else {
                    *prime_fd = ret;
                    ret = 0;
          }

          goto out;

fail_put_dmabuf:
          dma_buf_put(dmabuf);
out:
          drm_gem_object_put_unlocked(obj);
out_unlock:
          mutex_unlock(&file_priv->prime.lock);

          return ret;
}
EXPORT_SYMBOL(drm_gem_prime_handle_to_fd);

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

          if (!dev->driver->prime_handle_to_fd)
                    return -ENOSYS;

          /* check flags are valid */
          if (args->flags & ~(DRM_CLOEXEC | DRM_RDWR))
                    return -EINVAL;

          return dev->driver->prime_handle_to_fd(dev, file_priv,
                              args->handle, args->flags, &args->fd);
}

/**
 * DOC: PRIME Helpers
 *
 * Drivers can implement &drm_gem_object_funcs.export and
 * &drm_driver.gem_prime_import in terms of simpler APIs by using the helper
 * functions drm_gem_prime_export() and drm_gem_prime_import(). These functions
 * implement dma-buf support in terms of some lower-level helpers, which are
 * again exported for drivers to use individually:
 *
 * Exporting buffers
 * ~~~~~~~~~~~~~~~~~
 *
 * Optional pinning of buffers is handled at dma-buf attach and detach time in
 * drm_gem_map_attach() and drm_gem_map_detach(). Backing storage itself is
 * handled by drm_gem_map_dma_buf() and drm_gem_unmap_dma_buf(), which relies on
 * &drm_gem_object_funcs.get_sg_table.
 *
 * For kernel-internal access there's drm_gem_dmabuf_vmap() and
 * drm_gem_dmabuf_vunmap(). Userspace mmap support is provided by
 * drm_gem_dmabuf_mmap().
 *
 * Note that these export helpers can only be used if the underlying backing
 * storage is fully coherent and either permanently pinned, or it is safe to pin
 * it indefinitely.
 *
 * FIXME: The underlying helper functions are named rather inconsistently.
 *
 * Exporting buffers
 * ~~~~~~~~~~~~~~~~~
 *
 * Importing dma-bufs using drm_gem_prime_import() relies on
 * &drm_driver.gem_prime_import_sg_table.
 *
 * Note that similarly to the export helpers this permanently pins the
 * underlying backing storage. Which is ok for scanout, but is not the best
 * option for sharing lots of buffers for rendering.
 */

/**
 * drm_gem_map_attach - dma_buf attach implementation for GEM
 * @dma_buf: buffer to attach device to
 * @attach: buffer attachment data
 *
 * Calls &drm_gem_object_funcs.pin for device specific handling. This can be
 * used as the &dma_buf_ops.attach callback. Must be used together with
 * drm_gem_map_detach().
 *
 * Returns 0 on success, negative error code on failure.
 */
int drm_gem_map_attach(struct dma_buf *dma_buf,
                           struct dma_buf_attachment *attach)
{
          struct drm_gem_object *obj = dma_buf->priv;

          return drm_gem_pin(obj);
}
EXPORT_SYMBOL(drm_gem_map_attach);

/**
 * drm_gem_map_detach - dma_buf detach implementation for GEM
 * @dma_buf: buffer to detach from
 * @attach: attachment to be detached
 *
 * Calls &drm_gem_object_funcs.pin for device specific handling.  Cleans up
 * &dma_buf_attachment from drm_gem_map_attach(). This can be used as the
 * &dma_buf_ops.detach callback.
 */
void drm_gem_map_detach(struct dma_buf *dma_buf,
                              struct dma_buf_attachment *attach)
{
          struct drm_gem_object *obj = dma_buf->priv;

          drm_gem_unpin(obj);
}
EXPORT_SYMBOL(drm_gem_map_detach);

/**
 * drm_gem_map_dma_buf - map_dma_buf implementation for GEM
 * @attach: attachment whose scatterlist is to be returned
 * @dir: direction of DMA transfer
 *
 * Calls &drm_gem_object_funcs.get_sg_table and then maps the scatterlist. This
 * can be used as the &dma_buf_ops.map_dma_buf callback. Should be used together
 * with drm_gem_unmap_dma_buf().
 *
 * Returns:sg_table containing the scatterlist to be returned; returns ERR_PTR
 * on error. May return -EINTR if it is interrupted by a signal.
 */
struct sg_table *drm_gem_map_dma_buf(struct dma_buf_attachment *attach,
                                             enum dma_data_direction dir)
{
          struct drm_gem_object *obj = attach->dmabuf->priv;
          struct sg_table *sgt;

          if (WARN_ON(dir == DMA_NONE))
                    return ERR_PTR(-EINVAL);

          if (obj->funcs)
                    sgt = obj->funcs->get_sg_table(obj);
          else
                    sgt = obj->dev->driver->gem_prime_get_sg_table(obj);

          if (!dma_map_sg_attrs(attach->dev, sgt->sgl, sgt->nents, dir,
                                    DMA_ATTR_SKIP_CPU_SYNC)) {
                    sg_free_table(sgt);
                    kfree(sgt);
                    sgt = ERR_PTR(-ENOMEM);
          }

          return sgt;
}
EXPORT_SYMBOL(drm_gem_map_dma_buf);

/**
 * drm_gem_unmap_dma_buf - unmap_dma_buf implementation for GEM
 * @attach: attachment to unmap buffer from
 * @sgt: scatterlist info of the buffer to unmap
 * @dir: direction of DMA transfer
 *
 * This can be used as the &dma_buf_ops.unmap_dma_buf callback.
 */
void drm_gem_unmap_dma_buf(struct dma_buf_attachment *attach,
                                 struct sg_table *sgt,
                                 enum dma_data_direction dir)
{
          if (!sgt)
                    return;

          dma_unmap_sg_attrs(attach->dev, sgt->sgl, sgt->nents, dir,
                                 DMA_ATTR_SKIP_CPU_SYNC);
          sg_free_table(sgt);
          kfree(sgt);
}
EXPORT_SYMBOL(drm_gem_unmap_dma_buf);

/**
 * drm_gem_dmabuf_vmap - dma_buf vmap implementation for GEM
 * @dma_buf: buffer to be mapped
 *
 * Sets up a kernel virtual mapping. This can be used as the &dma_buf_ops.vmap
 * callback. Calls into &drm_gem_object_funcs.vmap for device specific handling.
 *
 * Returns the kernel virtual address or NULL on failure.
 */
void *drm_gem_dmabuf_vmap(struct dma_buf *dma_buf)
{
          struct drm_gem_object *obj = dma_buf->priv;
          void *vaddr;

          vaddr = drm_gem_vmap(obj);
          if (IS_ERR(vaddr))
                    vaddr = NULL;

          return vaddr;
}
EXPORT_SYMBOL(drm_gem_dmabuf_vmap);

/**
 * drm_gem_dmabuf_vunmap - dma_buf vunmap implementation for GEM
 * @dma_buf: buffer to be unmapped
 * @vaddr: the virtual address of the buffer
 *
 * Releases a kernel virtual mapping. This can be used as the
 * &dma_buf_ops.vunmap callback. Calls into &drm_gem_object_funcs.vunmap for device specific handling.
 */
void drm_gem_dmabuf_vunmap(struct dma_buf *dma_buf, void *vaddr)
{
          struct drm_gem_object *obj = dma_buf->priv;

          drm_gem_vunmap(obj, vaddr);
}
EXPORT_SYMBOL(drm_gem_dmabuf_vunmap);

/**
 * drm_gem_prime_mmap - PRIME mmap function for GEM drivers
 * @obj: GEM object
 * @vma: Virtual address range
 *
 * This function sets up a userspace mapping for PRIME exported buffers using
 * the same codepath that is used for regular GEM buffer mapping on the DRM fd.
 * The fake GEM offset is added to vma->vm_pgoff and &drm_driver->fops->mmap is
 * called to set up the mapping.
 *
 * Drivers can use this as their &drm_driver.gem_prime_mmap callback.
 */
#ifdef __NetBSD__
int drm_gem_prime_mmap(struct drm_gem_object *obj, off_t *offp, size_t size,
    int prot, int *flagsp, int *advicep, struct uvm_object **uobjp,
    int *maxprotp)
#else
int drm_gem_prime_mmap(struct drm_gem_object *obj, struct vm_area_struct *vma)
#endif
{
          struct drm_file *priv;
          struct file *fil;
          int ret;

          /* Add the fake offset */
#ifdef __NetBSD__
          *offp += drm_vma_node_start(&obj->vma_node);
#else
          vma->vm_pgoff += drm_vma_node_start(&obj->vma_node);
#endif

          if (obj->funcs && obj->funcs->mmap) {
#ifdef __NetBSD__
                    ret = obj->funcs->mmap(obj, offp, size, prot, flagsp, advicep,
                        uobjp, maxprotp);
#else
                    ret = obj->funcs->mmap(obj, vma);
#endif
                    if (ret)
                              return ret;
#ifndef __NetBSD__
                    vma->vm_private_data = obj;
#endif
                    drm_gem_object_get(obj);
                    return 0;
          }

          priv = kzalloc(sizeof(*priv), GFP_KERNEL);
          fil = kzalloc(sizeof(*fil), GFP_KERNEL);
          if (!priv || !fil) {
                    ret = -ENOMEM;
                    goto out;
          }

          /* Used by drm_gem_mmap() to lookup the GEM object */
          priv->minor = obj->dev->primary;
#ifdef __NetBSD__
          fil->f_data = priv;
#else
          fil->private_data = priv;
#endif

          ret = drm_vma_node_allow(&obj->vma_node, priv);
          if (ret)
                    goto out;

#ifdef __NetBSD__
          KASSERT(size > 0);
          ret = obj->dev->driver->mmap_object(obj->dev, *offp, size, prot, uobjp,
              offp, fil);
#else
          ret = obj->dev->driver->fops->mmap(fil, vma);
#endif

          drm_vma_node_revoke(&obj->vma_node, priv);
out:
          kfree(priv);
          kfree(fil);

          return ret;
}
EXPORT_SYMBOL(drm_gem_prime_mmap);

/**
 * drm_gem_dmabuf_mmap - dma_buf mmap implementation for GEM
 * @dma_buf: buffer to be mapped
 * @vma: virtual address range
 *
 * Provides memory mapping for the buffer. This can be used as the
 * &dma_buf_ops.mmap callback. It just forwards to &drm_driver.gem_prime_mmap,
 * which should be set to drm_gem_prime_mmap().
 *
 * FIXME: There's really no point to this wrapper, drivers which need anything
 * else but drm_gem_prime_mmap can roll their own &dma_buf_ops.mmap callback.
 *
 * Returns 0 on success or a negative error code on failure.
 */
#ifdef __NetBSD__
int
drm_gem_dmabuf_mmap(struct dma_buf *dma_buf, off_t *offp, size_t size,
    int prot, int *flagsp, int *advicep, struct uvm_object **uobjp,
    int *maxprotp)
#else
int drm_gem_dmabuf_mmap(struct dma_buf *dma_buf, struct vm_area_struct *vma)
#endif
{
          struct drm_gem_object *obj = dma_buf->priv;
          struct drm_device *dev = obj->dev;

          if (!dev->driver->gem_prime_mmap)
                    return -ENOSYS;

#ifdef __NetBSD__
          KASSERT(size > 0);
          return dev->driver->gem_prime_mmap(obj, offp, size, prot, flagsp,
              advicep, uobjp, maxprotp);
#else
          return dev->driver->gem_prime_mmap(obj, vma);
#endif
}
EXPORT_SYMBOL(drm_gem_dmabuf_mmap);

static const struct dma_buf_ops drm_gem_prime_dmabuf_ops =  {
          .cache_sgt_mapping = true,
          .attach = drm_gem_map_attach,
          .detach = drm_gem_map_detach,
          .map_dma_buf = drm_gem_map_dma_buf,
          .unmap_dma_buf = drm_gem_unmap_dma_buf,
          .release = drm_gem_dmabuf_release,
          .mmap = drm_gem_dmabuf_mmap,
          .vmap = drm_gem_dmabuf_vmap,
          .vunmap = drm_gem_dmabuf_vunmap,
};

/**
 * drm_prime_pages_to_sg - converts a page array into an sg list
 * @pages: pointer to the array of page pointers to convert
 * @nr_pages: length of the page vector
 *
 * This helper creates an sg table object from a set of pages
 * the driver is responsible for mapping the pages into the
 * importers address space for use with dma_buf itself.
 *
 * This is useful for implementing &drm_gem_object_funcs.get_sg_table.
 */
struct sg_table *drm_prime_pages_to_sg(struct page **pages, unsigned int nr_pages)
{
          struct sg_table *sg = NULL;
          int ret;

          sg = kmalloc(sizeof(struct sg_table), GFP_KERNEL);
          if (!sg) {
                    ret = -ENOMEM;
                    goto out;
          }

          ret = sg_alloc_table_from_pages(sg, pages, nr_pages, 0,
                                        nr_pages << PAGE_SHIFT, GFP_KERNEL);
          if (ret)
                    goto out;

          return sg;
out:
          kfree(sg);
          return ERR_PTR(ret);
}
EXPORT_SYMBOL(drm_prime_pages_to_sg);

/**
 * drm_gem_prime_export - helper library implementation of the export callback
 * @obj: GEM object to export
 * @flags: flags like DRM_CLOEXEC and DRM_RDWR
 *
 * This is the implementation of the &drm_gem_object_funcs.export functions for GEM drivers
 * using the PRIME helpers. It is used as the default in
 * drm_gem_prime_handle_to_fd().
 */
struct dma_buf *drm_gem_prime_export(struct drm_gem_object *obj,
                                             int flags)
{
          struct drm_device *dev = obj->dev;
          struct dma_buf_export_info exp_info = {
#ifndef __NetBSD__
                    .exp_name = KBUILD_MODNAME, /* white lie for debug */
                    .owner = dev->driver->fops->owner,
#endif
                    .ops = &drm_gem_prime_dmabuf_ops,
                    .size = obj->size,
                    .flags = flags,
                    .priv = obj,
                    .resv = obj->resv,
          };

          return drm_gem_dmabuf_export(dev, &exp_info);
}
EXPORT_SYMBOL(drm_gem_prime_export);

/**
 * drm_gem_prime_import_dev - core implementation of the import callback
 * @dev: drm_device to import into
 * @dma_buf: dma-buf object to import
 * @attach_dev: struct device to dma_buf attach
 *
 * This is the core of drm_gem_prime_import(). It's designed to be called by
 * drivers who want to use a different device structure than &drm_device.dev for
 * attaching via dma_buf. This function calls
 * &drm_driver.gem_prime_import_sg_table internally.
 *
 * Drivers must arrange to call drm_prime_gem_destroy() from their
 * &drm_gem_object_funcs.free hook when using this function.
 */
#ifdef __NetBSD__
struct drm_gem_object *drm_gem_prime_import_dev(struct drm_device *dev,
                                                      struct dma_buf *dma_buf,
                                                      bus_dma_tag_t attach_dev)
#else
struct drm_gem_object *drm_gem_prime_import_dev(struct drm_device *dev,
                                                      struct dma_buf *dma_buf,
                                                      struct device *attach_dev)
#endif
{
          struct dma_buf_attachment *attach;
          struct sg_table *sgt;
          struct drm_gem_object *obj;
          int ret;

          if (dma_buf->ops == &drm_gem_prime_dmabuf_ops) {
                    obj = dma_buf->priv;
                    if (obj->dev == dev) {
                              /*
                               * Importing dmabuf exported from out own gem increases
                               * refcount on gem itself instead of f_count of dmabuf.
                               */
                              drm_gem_object_get(obj);
                              return obj;
                    }
          }

          if (!dev->driver->gem_prime_import_sg_table)
                    return ERR_PTR(-EINVAL);

          attach = dma_buf_attach(dma_buf, attach_dev);
          if (IS_ERR(attach))
                    return ERR_CAST(attach);

          get_dma_buf(dma_buf);

          sgt = dma_buf_map_attachment(attach, DMA_BIDIRECTIONAL);
          if (IS_ERR(sgt)) {
                    ret = PTR_ERR(sgt);
                    goto fail_detach;
          }

          obj = dev->driver->gem_prime_import_sg_table(dev, attach, sgt);
          if (IS_ERR(obj)) {
                    ret = PTR_ERR(obj);
                    goto fail_unmap;
          }

          obj->import_attach = attach;
          obj->resv = dma_buf->resv;

          return obj;

fail_unmap:
          dma_buf_unmap_attachment(attach, sgt, DMA_BIDIRECTIONAL);
fail_detach:
          dma_buf_detach(dma_buf, attach);
          dma_buf_put(dma_buf);

          return ERR_PTR(ret);
}
EXPORT_SYMBOL(drm_gem_prime_import_dev);

/**
 * drm_gem_prime_import - helper library implementation of the import callback
 * @dev: drm_device to import into
 * @dma_buf: dma-buf object to import
 *
 * This is the implementation of the gem_prime_import functions for GEM drivers
 * using the PRIME helpers. Drivers can use this as their
 * &drm_driver.gem_prime_import implementation. It is used as the default
 * implementation in drm_gem_prime_fd_to_handle().
 *
 * Drivers must arrange to call drm_prime_gem_destroy() from their
 * &drm_gem_object_funcs.free hook when using this function.
 */
struct drm_gem_object *drm_gem_prime_import(struct drm_device *dev,
                                                      struct dma_buf *dma_buf)
{
#ifdef __NetBSD__
          return drm_gem_prime_import_dev(dev, dma_buf, dev->dmat);
#else
          return drm_gem_prime_import_dev(dev, dma_buf, dev->dev);
#endif
}
EXPORT_SYMBOL(drm_gem_prime_import);

#ifdef __NetBSD__

struct sg_table *
drm_prime_bus_dmamem_to_sg(bus_dma_tag_t dmat, const bus_dma_segment_t *segs,
    int nsegs)
{
          struct sg_table *sg;
          int ret;

          sg = kmalloc(sizeof(*sg), GFP_KERNEL);
          if (sg == NULL) {
                    ret = -ENOMEM;
                    goto out;
          }

          ret = sg_alloc_table_from_bus_dmamem(sg, dmat, segs, nsegs,
              GFP_KERNEL);
          if (ret)
                    goto out;

          return sg;
out:
          kfree(sg);
          return ERR_PTR(ret);
}

bus_size_t
drm_prime_sg_size(struct sg_table *sg)
{

          return sg->sgl->sg_npgs << PAGE_SHIFT;
}

void
drm_prime_sg_free(struct sg_table *sg)
{

          sg_free_table(sg);
          kfree(sg);
}

int
drm_prime_sg_to_bus_dmamem(bus_dma_tag_t dmat, bus_dma_segment_t *segs,
    int nsegs, int *rsegs, const struct sg_table *sgt)
{

          /* XXX errno NetBSD->Linux */
          return -bus_dmamem_import_pages(dmat, segs, nsegs, rsegs,
              sgt->sgl->sg_pgs, sgt->sgl->sg_npgs);
}

int
drm_prime_bus_dmamap_load_sgt(bus_dma_tag_t dmat, bus_dmamap_t map,
    struct sg_table *sgt)
{
          bus_dma_segment_t *segs;
          bus_size_t size = drm_prime_sg_size(sgt);
          int nsegs = sgt->sgl->sg_npgs;
          int ret;

          segs = kcalloc(sgt->sgl->sg_npgs, sizeof(segs[0]), GFP_KERNEL);
          if (segs == NULL) {
                    ret = -ENOMEM;
                    goto out0;
          }

          ret = drm_prime_sg_to_bus_dmamem(dmat, segs, nsegs, &nsegs, sgt);
          if (ret)
                    goto out1;
          KASSERT(nsegs <= sgt->sgl->sg_npgs);

          /* XXX errno NetBSD->Linux */
          ret = -bus_dmamap_load_raw(dmat, map, segs, nsegs, size,
              BUS_DMA_NOWAIT);
          if (ret)
                    goto out1;

out1:     kfree(segs);
out0:     return ret;
}

bool
drm_prime_sg_importable(bus_dma_tag_t dmat, struct sg_table *sgt)
{
          unsigned i;

          for (i = 0; i < sgt->sgl->sg_npgs; i++) {
                    if (bus_dmatag_bounces_paddr(dmat,
                              VM_PAGE_TO_PHYS(&sgt->sgl->sg_pgs[i]->p_vmp)))
                              return false;
          }
          return true;
}

#else  /* !__NetBSD__ */

/**
 * drm_prime_sg_to_page_addr_arrays - convert an sg table into a page array
 * @sgt: scatter-gather table to convert
 * @pages: optional array of page pointers to store the page array in
 * @addrs: optional array to store the dma bus address of each page
 * @max_entries: size of both the passed-in arrays
 *
 * Exports an sg table into an array of pages and addresses. This is currently
 * required by the TTM driver in order to do correct fault handling.
 *
 * Drivers can use this in their &drm_driver.gem_prime_import_sg_table
 * implementation.
 */
int drm_prime_sg_to_page_addr_arrays(struct sg_table *sgt, struct page **pages,
                                             dma_addr_t *addrs, int max_entries)
{
          unsigned count;
          struct scatterlist *sg;
          struct page *page;
          u32 len, index;
          dma_addr_t addr;

          index = 0;
          for_each_sg(sgt->sgl, sg, sgt->nents, count) {
                    len = sg->length;
                    page = sg_page(sg);
                    addr = sg_dma_address(sg);

                    while (len > 0) {
                              if (WARN_ON(index >= max_entries))
                                        return -1;
                              if (pages)
                                        pages[index] = page;
                              if (addrs)
                                        addrs[index] = addr;

                              page++;
                              addr += PAGE_SIZE;
                              len -= PAGE_SIZE;
                              index++;
                    }
          }
          return 0;
}
EXPORT_SYMBOL(drm_prime_sg_to_page_addr_arrays);

#endif    /* __NetBSD__ */

/**
 * drm_prime_gem_destroy - helper to clean up a PRIME-imported GEM object
 * @obj: GEM object which was created from a dma-buf
 * @sg: the sg-table which was pinned at import time
 *
 * This is the cleanup functions which GEM drivers need to call when they use
 * drm_gem_prime_import() or drm_gem_prime_import_dev() to import dma-bufs.
 */
void drm_prime_gem_destroy(struct drm_gem_object *obj, struct sg_table *sg)
{
          struct dma_buf_attachment *attach;
          struct dma_buf *dma_buf;
          attach = obj->import_attach;
          if (sg)
                    dma_buf_unmap_attachment(attach, sg, DMA_BIDIRECTIONAL);
          dma_buf = attach->dmabuf;
          dma_buf_detach(attach->dmabuf, attach);
          /* remove the reference */
          dma_buf_put(dma_buf);
}
EXPORT_SYMBOL(drm_prime_gem_destroy);