drivers/gpu/drm/drm_client.c - kernel/common - Git at Google

 // SPDX-License-Identifier: GPL-2.0 or MIT
 /*
  * Copyright 2018 Noralf Trønnes
  */

 #include <linux/iosys-map.h>
 #include <linux/list.h>
 #include <linux/module.h>
 #include <linux/mutex.h>
 #include <linux/seq_file.h>
 #include <linux/slab.h>

 #include <drm/drm_client.h>
 #include <drm/drm_debugfs.h>
 #include <drm/drm_device.h>
 #include <drm/drm_drv.h>
 #include <drm/drm_file.h>
 #include <drm/drm_fourcc.h>
 #include <drm/drm_framebuffer.h>
 #include <drm/drm_gem.h>
 #include <drm/drm_mode.h>
 #include <drm/drm_print.h>

 #include "drm_crtc_internal.h"
 #include "drm_internal.h"

 /**
  * DOC: overview
  *
  * This library provides support for clients running in the kernel like fbdev and bootsplash.
  *
  * GEM drivers which provide a GEM based dumb buffer with a virtual address are supported.
  */

 static int drm_client_open(struct drm_client_dev *client)
 {
 	struct drm_device *dev = client->dev;
 	struct drm_file *file;

 	file = drm_file_alloc(dev->primary);
 	if (IS_ERR(file))
 		return PTR_ERR(file);

 	mutex_lock(&dev->filelist_mutex);
 	list_add(&file->lhead, &dev->filelist_internal);
 	mutex_unlock(&dev->filelist_mutex);

 	client->file = file;

 	return 0;
 }

 static void drm_client_close(struct drm_client_dev *client)
 {
 	struct drm_device *dev = client->dev;

 	mutex_lock(&dev->filelist_mutex);
 	list_del(&client->file->lhead);
 	mutex_unlock(&dev->filelist_mutex);

 	drm_file_free(client->file);
 }

 /**
  * drm_client_init - Initialise a DRM client
  * @dev: DRM device
  * @client: DRM client
  * @name: Client name
  * @funcs: DRM client functions (optional)
  *
  * This initialises the client and opens a &drm_file.
  * Use drm_client_register() to complete the process.
  * The caller needs to hold a reference on @dev before calling this function.
  * The client is freed when the &drm_device is unregistered. See drm_client_release().
  *
  * Returns:
  * Zero on success or negative error code on failure.
  */
 int drm_client_init(struct drm_device *dev, struct drm_client_dev *client,
 		    const char *name, const struct drm_client_funcs *funcs)
 {
 	int ret;

 	if (!drm_core_check_feature(dev, DRIVER_MODESET) || !dev->driver->dumb_create)
 		return -EOPNOTSUPP;

 	if (funcs && !try_module_get(funcs->owner))
 		return -ENODEV;

 	client->dev = dev;
 	client->name = name;
 	client->funcs = funcs;

 	ret = drm_client_modeset_create(client);
 	if (ret)
 		goto err_put_module;

 	ret = drm_client_open(client);
 	if (ret)
 		goto err_free;

 	drm_dev_get(dev);

 	return 0;

 err_free:
 	drm_client_modeset_free(client);
 err_put_module:
 	if (funcs)
 		module_put(funcs->owner);

 	return ret;
 }
 EXPORT_SYMBOL(drm_client_init);

 /**
  * drm_client_register - Register client
  * @client: DRM client
  *
  * Add the client to the &drm_device client list to activate its callbacks.
  * @client must be initialized by a call to drm_client_init(). After
  * drm_client_register() it is no longer permissible to call drm_client_release()
  * directly (outside the unregister callback), instead cleanup will happen
  * automatically on driver unload.
  *
  * Registering a client generates a hotplug event that allows the client
  * to set up its display from pre-existing outputs. The client must have
  * initialized its state to able to handle the hotplug event successfully.
  */
 void drm_client_register(struct drm_client_dev *client)
 {
 	struct drm_device *dev = client->dev;
 	int ret;

 	mutex_lock(&dev->clientlist_mutex);
 	list_add(&client->list, &dev->clientlist);

 	if (client->funcs && client->funcs->hotplug) {
 		/*
 		 * Perform an initial hotplug event to pick up the
 		 * display configuration for the client. This step
 		 * has to be performed *after* registering the client
 		 * in the list of clients, or a concurrent hotplug
 		 * event might be lost; leaving the display off.
 		 *
 		 * Hold the clientlist_mutex as for a regular hotplug
 		 * event.
 		 */
 		ret = client->funcs->hotplug(client);
 		if (ret)
 			drm_dbg_kms(dev, "client hotplug ret=%d\n", ret);
 	}
 	mutex_unlock(&dev->clientlist_mutex);
 }
 EXPORT_SYMBOL(drm_client_register);

 /**
  * drm_client_release - Release DRM client resources
  * @client: DRM client
  *
  * Releases resources by closing the &drm_file that was opened by drm_client_init().
  * It is called automatically if the &drm_client_funcs.unregister callback is _not_ set.
  *
  * This function should only be called from the unregister callback. An exception
  * is fbdev which cannot free the buffer if userspace has open file descriptors.
  *
  * Note:
  * Clients cannot initiate a release by themselves. This is done to keep the code simple.
  * The driver has to be unloaded before the client can be unloaded.
  */
 void drm_client_release(struct drm_client_dev *client)
 {
 	struct drm_device *dev = client->dev;

 	drm_dbg_kms(dev, "%s\n", client->name);

 	drm_client_modeset_free(client);
 	drm_client_close(client);
 	drm_dev_put(dev);
 	if (client->funcs)
 		module_put(client->funcs->owner);
 }
 EXPORT_SYMBOL(drm_client_release);

 void drm_client_dev_unregister(struct drm_device *dev)
 {
 	struct drm_client_dev *client, *tmp;

 	if (!drm_core_check_feature(dev, DRIVER_MODESET))
 		return;

 	mutex_lock(&dev->clientlist_mutex);
 	list_for_each_entry_safe(client, tmp, &dev->clientlist, list) {
 		list_del(&client->list);
 		if (client->funcs && client->funcs->unregister) {
 			client->funcs->unregister(client);
 		} else {
 			drm_client_release(client);
 			kfree(client);
 		}
 	}
 	mutex_unlock(&dev->clientlist_mutex);
 }

 /**
  * drm_client_dev_hotplug - Send hotplug event to clients
  * @dev: DRM device
  *
  * This function calls the &drm_client_funcs.hotplug callback on the attached clients.
  *
  * drm_kms_helper_hotplug_event() calls this function, so drivers that use it
  * don't need to call this function themselves.
  */
 void drm_client_dev_hotplug(struct drm_device *dev)
 {
 	struct drm_client_dev *client;
 	int ret;

 	if (!drm_core_check_feature(dev, DRIVER_MODESET))
 		return;

 	mutex_lock(&dev->clientlist_mutex);
 	list_for_each_entry(client, &dev->clientlist, list) {
 		if (!client->funcs || !client->funcs->hotplug)
 			continue;

 		ret = client->funcs->hotplug(client);
 		drm_dbg_kms(dev, "%s: ret=%d\n", client->name, ret);
 	}
 	mutex_unlock(&dev->clientlist_mutex);
 }
 EXPORT_SYMBOL(drm_client_dev_hotplug);

 void drm_client_dev_restore(struct drm_device *dev)
 {
 	struct drm_client_dev *client;
 	int ret;

 	if (!drm_core_check_feature(dev, DRIVER_MODESET))
 		return;

 	mutex_lock(&dev->clientlist_mutex);
 	list_for_each_entry(client, &dev->clientlist, list) {
 		if (!client->funcs || !client->funcs->restore)
 			continue;

 		ret = client->funcs->restore(client);
 		drm_dbg_kms(dev, "%s: ret=%d\n", client->name, ret);
 		if (!ret) /* The first one to return zero gets the privilege to restore */
 			break;
 	}
 	mutex_unlock(&dev->clientlist_mutex);
 }

 static void drm_client_buffer_delete(struct drm_client_buffer *buffer)
 {
 	struct drm_device *dev = buffer->client->dev;

 	drm_gem_vunmap(buffer->gem, &buffer->map);

 	if (buffer->gem)
 		drm_gem_object_put(buffer->gem);

 	if (buffer->handle)
 		drm_mode_destroy_dumb(dev, buffer->handle, buffer->client->file);

 	kfree(buffer);
 }

 static struct drm_client_buffer *
 drm_client_buffer_create(struct drm_client_dev *client, u32 width, u32 height, u32 format)
 {
 	const struct drm_format_info *info = drm_format_info(format);
 	struct drm_mode_create_dumb dumb_args = { };
 	struct drm_device *dev = client->dev;
 	struct drm_client_buffer *buffer;
 	struct drm_gem_object *obj;
 	int ret;

 	buffer = kzalloc(sizeof(*buffer), GFP_KERNEL);
 	if (!buffer)
 		return ERR_PTR(-ENOMEM);

 	buffer->client = client;

 	dumb_args.width = width;
 	dumb_args.height = height;
 	dumb_args.bpp = drm_format_info_bpp(info, 0);
 	ret = drm_mode_create_dumb(dev, &dumb_args, client->file);
 	if (ret)
 		goto err_delete;

 	buffer->handle = dumb_args.handle;
 	buffer->pitch = dumb_args.pitch;

 	obj = drm_gem_object_lookup(client->file, dumb_args.handle);
 	if (!obj)  {
 		ret = -ENOENT;
 		goto err_delete;
 	}

 	buffer->gem = obj;

 	return buffer;

 err_delete:
 	drm_client_buffer_delete(buffer);

 	return ERR_PTR(ret);
 }

 /**
  * drm_client_buffer_vmap - Map DRM client buffer into address space
  * @buffer: DRM client buffer
  * @map_copy: Returns the mapped memory's address
  *
  * This function maps a client buffer into kernel address space. If the
  * buffer is already mapped, it returns the existing mapping's address.
  *
  * Client buffer mappings are not ref'counted. Each call to
  * drm_client_buffer_vmap() should be followed by a call to
  * drm_client_buffer_vunmap(); or the client buffer should be mapped
  * throughout its lifetime.
  *
  * The returned address is a copy of the internal value. In contrast to
  * other vmap interfaces, you don't need it for the client's vunmap
  * function. So you can modify it at will during blit and draw operations.
  *
  * Returns:
  *	0 on success, or a negative errno code otherwise.
  */
 int
 drm_client_buffer_vmap(struct drm_client_buffer *buffer,
 		       struct iosys_map *map_copy)
 {
 	struct iosys_map *map = &buffer->map;
 	int ret;

 	/*
 	 * FIXME: The dependency on GEM here isn't required, we could
 	 * convert the driver handle to a dma-buf instead and use the
 	 * backend-agnostic dma-buf vmap support instead. This would
 	 * require that the handle2fd prime ioctl is reworked to pull the
 	 * fd_install step out of the driver backend hooks, to make that
 	 * final step optional for internal users.
 	 */
 	ret = drm_gem_vmap(buffer->gem, map);
 	if (ret)
 		return ret;

 	*map_copy = *map;

 	return 0;
 }
 EXPORT_SYMBOL(drm_client_buffer_vmap);

 /**
  * drm_client_buffer_vunmap - Unmap DRM client buffer
  * @buffer: DRM client buffer
  *
  * This function removes a client buffer's memory mapping. Calling this
  * function is only required by clients that manage their buffer mappings
  * by themselves.
  */
 void drm_client_buffer_vunmap(struct drm_client_buffer *buffer)
 {
 	struct iosys_map *map = &buffer->map;

 	drm_gem_vunmap(buffer->gem, map);
 }
 EXPORT_SYMBOL(drm_client_buffer_vunmap);

 static void drm_client_buffer_rmfb(struct drm_client_buffer *buffer)
 {
 	int ret;

 	if (!buffer->fb)
 		return;

 	ret = drm_mode_rmfb(buffer->client->dev, buffer->fb->base.id, buffer->client->file);
 	if (ret)
 		drm_err(buffer->client->dev,
 			"Error removing FB:%u (%d)\n", buffer->fb->base.id, ret);

 	buffer->fb = NULL;
 }

 static int drm_client_buffer_addfb(struct drm_client_buffer *buffer,
 				   u32 width, u32 height, u32 format)
 {
 	struct drm_client_dev *client = buffer->client;
 	struct drm_mode_fb_cmd fb_req = { };
 	const struct drm_format_info *info;
 	int ret;

 	info = drm_format_info(format);
 	fb_req.bpp = drm_format_info_bpp(info, 0);
 	fb_req.depth = info->depth;
 	fb_req.width = width;
 	fb_req.height = height;
 	fb_req.handle = buffer->handle;
 	fb_req.pitch = buffer->pitch;

 	ret = drm_mode_addfb(client->dev, &fb_req, client->file);
 	if (ret)
 		return ret;

 	buffer->fb = drm_framebuffer_lookup(client->dev, buffer->client->file, fb_req.fb_id);
 	if (WARN_ON(!buffer->fb))
 		return -ENOENT;

 	/* drop the reference we picked up in framebuffer lookup */
 	drm_framebuffer_put(buffer->fb);

 	strscpy(buffer->fb->comm, client->name, TASK_COMM_LEN);

 	return 0;
 }

 /**
  * drm_client_framebuffer_create - Create a client framebuffer
  * @client: DRM client
  * @width: Framebuffer width
  * @height: Framebuffer height
  * @format: Buffer format
  *
  * This function creates a &drm_client_buffer which consists of a
  * &drm_framebuffer backed by a dumb buffer.
  * Call drm_client_framebuffer_delete() to free the buffer.
  *
  * Returns:
  * Pointer to a client buffer or an error pointer on failure.
  */
 struct drm_client_buffer *
 drm_client_framebuffer_create(struct drm_client_dev *client, u32 width, u32 height, u32 format)
 {
 	struct drm_client_buffer *buffer;
 	int ret;

 	buffer = drm_client_buffer_create(client, width, height, format);
 	if (IS_ERR(buffer))
 		return buffer;

 	ret = drm_client_buffer_addfb(buffer, width, height, format);
 	if (ret) {
 		drm_client_buffer_delete(buffer);
 		return ERR_PTR(ret);
 	}

 	return buffer;
 }
 EXPORT_SYMBOL(drm_client_framebuffer_create);

 /**
  * drm_client_framebuffer_delete - Delete a client framebuffer
  * @buffer: DRM client buffer (can be NULL)
  */
 void drm_client_framebuffer_delete(struct drm_client_buffer *buffer)
 {
 	if (!buffer)
 		return;

 	drm_client_buffer_rmfb(buffer);
 	drm_client_buffer_delete(buffer);
 }
 EXPORT_SYMBOL(drm_client_framebuffer_delete);

 /**
  * drm_client_framebuffer_flush - Manually flush client framebuffer
  * @buffer: DRM client buffer (can be NULL)
  * @rect: Damage rectangle (if NULL flushes all)
  *
  * This calls &drm_framebuffer_funcs->dirty (if present) to flush buffer changes
  * for drivers that need it.
  *
  * Returns:
  * Zero on success or negative error code on failure.
  */
 int drm_client_framebuffer_flush(struct drm_client_buffer *buffer, struct drm_rect *rect)
 {
 	if (!buffer || !buffer->fb || !buffer->fb->funcs->dirty)
 		return 0;

 	if (rect) {
 		struct drm_clip_rect clip = {
 			.x1 = rect->x1,
 			.y1 = rect->y1,
 			.x2 = rect->x2,
 			.y2 = rect->y2,
 		};

 		return buffer->fb->funcs->dirty(buffer->fb, buffer->client->file,
 						0, 0, &clip, 1);
 	}

 	return buffer->fb->funcs->dirty(buffer->fb, buffer->client->file,
 					0, 0, NULL, 0);
 }
 EXPORT_SYMBOL(drm_client_framebuffer_flush);

 #ifdef CONFIG_DEBUG_FS
 static int drm_client_debugfs_internal_clients(struct seq_file *m, void *data)
 {
 	struct drm_info_node *node = m->private;
 	struct drm_device *dev = node->minor->dev;
 	struct drm_printer p = drm_seq_file_printer(m);
 	struct drm_client_dev *client;

 	mutex_lock(&dev->clientlist_mutex);
 	list_for_each_entry(client, &dev->clientlist, list)
 		drm_printf(&p, "%s\n", client->name);
 	mutex_unlock(&dev->clientlist_mutex);

 	return 0;
 }

 static const struct drm_info_list drm_client_debugfs_list[] = {
 	{ "internal_clients", drm_client_debugfs_internal_clients, 0 },
 };

 void drm_client_debugfs_init(struct drm_minor *minor)
 {
 	drm_debugfs_create_files(drm_client_debugfs_list,
 				 ARRAY_SIZE(drm_client_debugfs_list),
 				 minor->debugfs_root, minor);
 }
 #endif
	// SPDX-License-Identifier: GPL-2.0 or MIT
	/*
	* Copyright 2018 Noralf Trønnes
	*/

	#include <linux/iosys-map.h>
	#include <linux/list.h>
	#include <linux/module.h>
	#include <linux/mutex.h>
	#include <linux/seq_file.h>
	#include <linux/slab.h>

	#include <drm/drm_client.h>
	#include <drm/drm_debugfs.h>
	#include <drm/drm_device.h>
	#include <drm/drm_drv.h>
	#include <drm/drm_file.h>
	#include <drm/drm_fourcc.h>
	#include <drm/drm_framebuffer.h>
	#include <drm/drm_gem.h>
	#include <drm/drm_mode.h>
	#include <drm/drm_print.h>

	#include "drm_crtc_internal.h"
	#include "drm_internal.h"

	/**
	* DOC: overview
	*
	* This library provides support for clients running in the kernel like fbdev and bootsplash.
	*
	* GEM drivers which provide a GEM based dumb buffer with a virtual address are supported.
	*/

	static int drm_client_open(struct drm_client_dev *client)
	{
	struct drm_device *dev = client->dev;
	struct drm_file *file;

	file = drm_file_alloc(dev->primary);
	if (IS_ERR(file))
	return PTR_ERR(file);

	mutex_lock(&dev->filelist_mutex);
	list_add(&file->lhead, &dev->filelist_internal);
	mutex_unlock(&dev->filelist_mutex);

	client->file = file;

	return 0;
	}

	static void drm_client_close(struct drm_client_dev *client)
	{
	struct drm_device *dev = client->dev;

	mutex_lock(&dev->filelist_mutex);
	list_del(&client->file->lhead);
	mutex_unlock(&dev->filelist_mutex);

	drm_file_free(client->file);
	}

	/**
	* drm_client_init - Initialise a DRM client
	* @dev: DRM device
	* @client: DRM client
	* @name: Client name
	* @funcs: DRM client functions (optional)
	*
	* This initialises the client and opens a &drm_file.
	* Use drm_client_register() to complete the process.
	* The caller needs to hold a reference on @dev before calling this function.
	* The client is freed when the &drm_device is unregistered. See drm_client_release().
	*
	* Returns:
	* Zero on success or negative error code on failure.
	*/
	int drm_client_init(struct drm_device dev, struct drm_client_dev client,
	const char name, const struct drm_client_funcs funcs)
	{
	int ret;

	if (!drm_core_check_feature(dev, DRIVER_MODESET) \|\| !dev->driver->dumb_create)
	return -EOPNOTSUPP;

	if (funcs && !try_module_get(funcs->owner))
	return -ENODEV;

	client->dev = dev;
	client->name = name;
	client->funcs = funcs;

	ret = drm_client_modeset_create(client);
	if (ret)
	goto err_put_module;

	ret = drm_client_open(client);
	if (ret)
	goto err_free;

	drm_dev_get(dev);

	return 0;

	err_free:
	drm_client_modeset_free(client);
	err_put_module:
	if (funcs)
	module_put(funcs->owner);

	return ret;
	}
	EXPORT_SYMBOL(drm_client_init);

	/**
	* drm_client_register - Register client
	* @client: DRM client
	*
	* Add the client to the &drm_device client list to activate its callbacks.
	* @client must be initialized by a call to drm_client_init(). After
	* drm_client_register() it is no longer permissible to call drm_client_release()
	* directly (outside the unregister callback), instead cleanup will happen
	* automatically on driver unload.
	*
	* Registering a client generates a hotplug event that allows the client
	* to set up its display from pre-existing outputs. The client must have
	* initialized its state to able to handle the hotplug event successfully.
	*/
	void drm_client_register(struct drm_client_dev *client)
	{
	struct drm_device *dev = client->dev;
	int ret;

	mutex_lock(&dev->clientlist_mutex);
	list_add(&client->list, &dev->clientlist);

	if (client->funcs && client->funcs->hotplug) {
	/*
	* Perform an initial hotplug event to pick up the
	* display configuration for the client. This step
	* has to be performed after registering the client
	* in the list of clients, or a concurrent hotplug
	* event might be lost; leaving the display off.
	*
	* Hold the clientlist_mutex as for a regular hotplug
	* event.
	*/
	ret = client->funcs->hotplug(client);
	if (ret)
	drm_dbg_kms(dev, "client hotplug ret=%d\n", ret);
	}
	mutex_unlock(&dev->clientlist_mutex);
	}
	EXPORT_SYMBOL(drm_client_register);

	/**
	* drm_client_release - Release DRM client resources
	* @client: DRM client
	*
	* Releases resources by closing the &drm_file that was opened by drm_client_init().
	* It is called automatically if the &drm_client_funcs.unregister callback is _not_ set.
	*
	* This function should only be called from the unregister callback. An exception
	* is fbdev which cannot free the buffer if userspace has open file descriptors.
	*
	* Note:
	* Clients cannot initiate a release by themselves. This is done to keep the code simple.
	* The driver has to be unloaded before the client can be unloaded.
	*/
	void drm_client_release(struct drm_client_dev *client)
	{
	struct drm_device *dev = client->dev;

	drm_dbg_kms(dev, "%s\n", client->name);

	drm_client_modeset_free(client);
	drm_client_close(client);
	drm_dev_put(dev);
	if (client->funcs)
	module_put(client->funcs->owner);
	}
	EXPORT_SYMBOL(drm_client_release);

	void drm_client_dev_unregister(struct drm_device *dev)
	{
	struct drm_client_dev client, tmp;

	if (!drm_core_check_feature(dev, DRIVER_MODESET))
	return;

	mutex_lock(&dev->clientlist_mutex);
	list_for_each_entry_safe(client, tmp, &dev->clientlist, list) {
	list_del(&client->list);
	if (client->funcs && client->funcs->unregister) {
	client->funcs->unregister(client);
	} else {
	drm_client_release(client);
	kfree(client);
	}
	}
	mutex_unlock(&dev->clientlist_mutex);
	}

	/**
	* drm_client_dev_hotplug - Send hotplug event to clients
	* @dev: DRM device
	*
	* This function calls the &drm_client_funcs.hotplug callback on the attached clients.
	*
	* drm_kms_helper_hotplug_event() calls this function, so drivers that use it
	* don't need to call this function themselves.
	*/
	void drm_client_dev_hotplug(struct drm_device *dev)
	{
	struct drm_client_dev *client;
	int ret;

	if (!drm_core_check_feature(dev, DRIVER_MODESET))
	return;

	mutex_lock(&dev->clientlist_mutex);
	list_for_each_entry(client, &dev->clientlist, list) {
	if (!client->funcs \|\| !client->funcs->hotplug)
	continue;

	ret = client->funcs->hotplug(client);
	drm_dbg_kms(dev, "%s: ret=%d\n", client->name, ret);
	}
	mutex_unlock(&dev->clientlist_mutex);
	}
	EXPORT_SYMBOL(drm_client_dev_hotplug);

	void drm_client_dev_restore(struct drm_device *dev)
	{
	struct drm_client_dev *client;
	int ret;

	if (!drm_core_check_feature(dev, DRIVER_MODESET))
	return;

	mutex_lock(&dev->clientlist_mutex);
	list_for_each_entry(client, &dev->clientlist, list) {
	if (!client->funcs \|\| !client->funcs->restore)
	continue;

	ret = client->funcs->restore(client);
	drm_dbg_kms(dev, "%s: ret=%d\n", client->name, ret);
	if (!ret) /* The first one to return zero gets the privilege to restore */
	break;
	}
	mutex_unlock(&dev->clientlist_mutex);
	}

	static void drm_client_buffer_delete(struct drm_client_buffer *buffer)
	{
	struct drm_device *dev = buffer->client->dev;

	drm_gem_vunmap(buffer->gem, &buffer->map);

	if (buffer->gem)
	drm_gem_object_put(buffer->gem);

	if (buffer->handle)
	drm_mode_destroy_dumb(dev, buffer->handle, buffer->client->file);

	kfree(buffer);
	}

	static struct drm_client_buffer *
	drm_client_buffer_create(struct drm_client_dev *client, u32 width, u32 height, u32 format)
	{
	const struct drm_format_info *info = drm_format_info(format);
	struct drm_mode_create_dumb dumb_args = { };
	struct drm_device *dev = client->dev;
	struct drm_client_buffer *buffer;
	struct drm_gem_object *obj;
	int ret;

	buffer = kzalloc(sizeof(*buffer), GFP_KERNEL);
	if (!buffer)
	return ERR_PTR(-ENOMEM);

	buffer->client = client;

	dumb_args.width = width;
	dumb_args.height = height;
	dumb_args.bpp = drm_format_info_bpp(info, 0);
	ret = drm_mode_create_dumb(dev, &dumb_args, client->file);
	if (ret)
	goto err_delete;

	buffer->handle = dumb_args.handle;
	buffer->pitch = dumb_args.pitch;

	obj = drm_gem_object_lookup(client->file, dumb_args.handle);
	if (!obj) {
	ret = -ENOENT;
	goto err_delete;
	}

	buffer->gem = obj;

	return buffer;

	err_delete:
	drm_client_buffer_delete(buffer);

	return ERR_PTR(ret);
	}

	/**
	* drm_client_buffer_vmap - Map DRM client buffer into address space
	* @buffer: DRM client buffer
	* @map_copy: Returns the mapped memory's address
	*
	* This function maps a client buffer into kernel address space. If the
	* buffer is already mapped, it returns the existing mapping's address.
	*
	* Client buffer mappings are not ref'counted. Each call to
	* drm_client_buffer_vmap() should be followed by a call to
	* drm_client_buffer_vunmap(); or the client buffer should be mapped
	* throughout its lifetime.
	*
	* The returned address is a copy of the internal value. In contrast to
	* other vmap interfaces, you don't need it for the client's vunmap
	* function. So you can modify it at will during blit and draw operations.
	*
	* Returns:
	* 0 on success, or a negative errno code otherwise.
	*/
	int
	drm_client_buffer_vmap(struct drm_client_buffer *buffer,
	struct iosys_map *map_copy)
	{
	struct iosys_map *map = &buffer->map;
	int ret;

	/*
	* FIXME: The dependency on GEM here isn't required, we could
	* convert the driver handle to a dma-buf instead and use the
	* backend-agnostic dma-buf vmap support instead. This would
	* require that the handle2fd prime ioctl is reworked to pull the
	* fd_install step out of the driver backend hooks, to make that
	* final step optional for internal users.
	*/
	ret = drm_gem_vmap(buffer->gem, map);
	if (ret)
	return ret;

	map_copy = map;

	return 0;
	}
	EXPORT_SYMBOL(drm_client_buffer_vmap);

	/**
	* drm_client_buffer_vunmap - Unmap DRM client buffer
	* @buffer: DRM client buffer
	*
	* This function removes a client buffer's memory mapping. Calling this
	* function is only required by clients that manage their buffer mappings
	* by themselves.
	*/
	void drm_client_buffer_vunmap(struct drm_client_buffer *buffer)
	{
	struct iosys_map *map = &buffer->map;

	drm_gem_vunmap(buffer->gem, map);
	}
	EXPORT_SYMBOL(drm_client_buffer_vunmap);

	static void drm_client_buffer_rmfb(struct drm_client_buffer *buffer)
	{
	int ret;

	if (!buffer->fb)
	return;

	ret = drm_mode_rmfb(buffer->client->dev, buffer->fb->base.id, buffer->client->file);
	if (ret)
	drm_err(buffer->client->dev,
	"Error removing FB:%u (%d)\n", buffer->fb->base.id, ret);

	buffer->fb = NULL;
	}

	static int drm_client_buffer_addfb(struct drm_client_buffer *buffer,
	u32 width, u32 height, u32 format)
	{
	struct drm_client_dev *client = buffer->client;
	struct drm_mode_fb_cmd fb_req = { };
	const struct drm_format_info *info;
	int ret;

	info = drm_format_info(format);
	fb_req.bpp = drm_format_info_bpp(info, 0);
	fb_req.depth = info->depth;
	fb_req.width = width;
	fb_req.height = height;
	fb_req.handle = buffer->handle;
	fb_req.pitch = buffer->pitch;

	ret = drm_mode_addfb(client->dev, &fb_req, client->file);
	if (ret)
	return ret;

	buffer->fb = drm_framebuffer_lookup(client->dev, buffer->client->file, fb_req.fb_id);
	if (WARN_ON(!buffer->fb))
	return -ENOENT;

	/* drop the reference we picked up in framebuffer lookup */
	drm_framebuffer_put(buffer->fb);

	strscpy(buffer->fb->comm, client->name, TASK_COMM_LEN);

	return 0;
	}

	/**
	* drm_client_framebuffer_create - Create a client framebuffer
	* @client: DRM client
	* @width: Framebuffer width
	* @height: Framebuffer height
	* @format: Buffer format
	*
	* This function creates a &drm_client_buffer which consists of a
	* &drm_framebuffer backed by a dumb buffer.
	* Call drm_client_framebuffer_delete() to free the buffer.
	*
	* Returns:
	* Pointer to a client buffer or an error pointer on failure.
	*/
	struct drm_client_buffer *
	drm_client_framebuffer_create(struct drm_client_dev *client, u32 width, u32 height, u32 format)
	{
	struct drm_client_buffer *buffer;
	int ret;

	buffer = drm_client_buffer_create(client, width, height, format);
	if (IS_ERR(buffer))
	return buffer;

	ret = drm_client_buffer_addfb(buffer, width, height, format);
	if (ret) {
	drm_client_buffer_delete(buffer);
	return ERR_PTR(ret);
	}

	return buffer;
	}
	EXPORT_SYMBOL(drm_client_framebuffer_create);

	/**
	* drm_client_framebuffer_delete - Delete a client framebuffer
	* @buffer: DRM client buffer (can be NULL)
	*/
	void drm_client_framebuffer_delete(struct drm_client_buffer *buffer)
	{
	if (!buffer)
	return;

	drm_client_buffer_rmfb(buffer);
	drm_client_buffer_delete(buffer);
	}
	EXPORT_SYMBOL(drm_client_framebuffer_delete);

	/**
	* drm_client_framebuffer_flush - Manually flush client framebuffer
	* @buffer: DRM client buffer (can be NULL)
	* @rect: Damage rectangle (if NULL flushes all)
	*
	* This calls &drm_framebuffer_funcs->dirty (if present) to flush buffer changes
	* for drivers that need it.
	*
	* Returns:
	* Zero on success or negative error code on failure.
	*/
	int drm_client_framebuffer_flush(struct drm_client_buffer buffer, struct drm_rect rect)
	{
	if (!buffer \|\| !buffer->fb \|\| !buffer->fb->funcs->dirty)
	return 0;

	if (rect) {
	struct drm_clip_rect clip = {
	.x1 = rect->x1,
	.y1 = rect->y1,
	.x2 = rect->x2,
	.y2 = rect->y2,
	};

	return buffer->fb->funcs->dirty(buffer->fb, buffer->client->file,
	0, 0, &clip, 1);
	}

	return buffer->fb->funcs->dirty(buffer->fb, buffer->client->file,
	0, 0, NULL, 0);
	}
	EXPORT_SYMBOL(drm_client_framebuffer_flush);

	#ifdef CONFIG_DEBUG_FS
	static int drm_client_debugfs_internal_clients(struct seq_file m, void data)
	{
	struct drm_info_node *node = m->private;
	struct drm_device *dev = node->minor->dev;
	struct drm_printer p = drm_seq_file_printer(m);
	struct drm_client_dev *client;

	mutex_lock(&dev->clientlist_mutex);
	list_for_each_entry(client, &dev->clientlist, list)
	drm_printf(&p, "%s\n", client->name);
	mutex_unlock(&dev->clientlist_mutex);

	return 0;
	}

	static const struct drm_info_list drm_client_debugfs_list[] = {
	{ "internal_clients", drm_client_debugfs_internal_clients, 0 },
	};

	void drm_client_debugfs_init(struct drm_minor *minor)
	{
	drm_debugfs_create_files(drm_client_debugfs_list,
	ARRAY_SIZE(drm_client_debugfs_list),
	minor->debugfs_root, minor);
	}
	#endif