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Commit c76f0f7c authored by Noralf Trønnes's avatar Noralf Trønnes
Browse files

drm: Begin an API for in-kernel clients 



This the beginning of an API for in-kernel clients.
First out is a way to get a framebuffer backed by a dumb buffer.

Only GEM drivers are supported.
The original idea of using an exported dma-buf was dropped because it
also creates an anonomous file descriptor which doesn't work when the
buffer is created from a kernel thread. The easy way out is to use
drm_driver.gem_prime_vmap to get the virtual address, which requires a
GEM object. This excludes the vmwgfx driver which is the only non-GEM
driver apart from the legacy ones. A solution for vmwgfx will have to be
worked out later if it wants to support the client API which it probably
will when we have a bootsplash client.

Suggested-by: default avatarDaniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: default avatarNoralf Trønnes <noralf@tronnes.org>
Reviewed-by: default avatarDaniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20180703160354.59955-2-noralf@tronnes.org
parent 5ba57bab

Documentation/gpu/drm-client.rst

0 → 100644
+12 −0
Original line number Diff line number Diff line 
=================

Kernel clients

=================



.. kernel-doc:: drivers/gpu/drm/drm_client.c

   :doc: overview



.. kernel-doc:: include/drm/drm_client.h

   :internal:



.. kernel-doc:: drivers/gpu/drm/drm_client.c

   :export:

Documentation/gpu/index.rst

+1 −0
Original line number Diff line number Diff line
@@ -10,6 +10,7 @@ Linux GPU Driver Developer's Guide 
   drm-kms

   drm-kms-helpers

   drm-uapi

   drm-client

   drivers

   vga-switcheroo

   vgaarbiter

drivers/gpu/drm/Makefile

+1 −1
Original line number Diff line number Diff line
@@ -18,7 +18,7 @@ drm-y := drm_auth.o drm_bufs.o drm_cache.o \ 
		drm_encoder.o drm_mode_object.o drm_property.o \

		drm_plane.o drm_color_mgmt.o drm_print.o \

		drm_dumb_buffers.o drm_mode_config.o drm_vblank.o \

		drm_syncobj.o drm_lease.o drm_writeback.o

		drm_syncobj.o drm_lease.o drm_writeback.o drm_client.o



drm-$(CONFIG_DRM_LIB_RANDOM) += lib/drm_random.o

drm-$(CONFIG_DRM_VM) += drm_vm.o

drivers/gpu/drm/drm_client.c

0 → 100644
+387 −0
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0

/*

 * Copyright 2018 Noralf Trønnes

 */



#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_gem.h>

#include <drm/drm_mode.h>

#include <drm/drm_print.h>

#include <drm/drmP.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.

 * Currently it's only partially implemented, just enough to support fbdev.

 *

 * 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);

}

EXPORT_SYMBOL(drm_client_close);



/**

 * drm_client_new - Create a DRM client

 * @dev: DRM device

 * @client: DRM client

 * @name: Client name

 * @funcs: DRM client functions (optional)

 *

 * 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_new(struct drm_device *dev, struct drm_client_dev *client,

		   const char *name, const struct drm_client_funcs *funcs)

{

	bool registered;

	int ret;



	if (!drm_core_check_feature(dev, DRIVER_MODESET) ||

	    !dev->driver->dumb_create || !dev->driver->gem_prime_vmap)

		return -ENOTSUPP;



	if (funcs && !try_module_get(funcs->owner))

		return -ENODEV;



	client->dev = dev;

	client->name = name;

	client->funcs = funcs;



	ret = drm_client_open(client);

	if (ret)

		goto err_put_module;



	mutex_lock(&dev->clientlist_mutex);

	registered = dev->registered;

	if (registered)

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

	mutex_unlock(&dev->clientlist_mutex);

	if (!registered) {

		ret = -ENODEV;

		goto err_close;

	}



	drm_dev_get(dev);



	return 0;



err_close:

	drm_client_close(client);

err_put_module:

	if (funcs)

		module_put(funcs->owner);



	return ret;

}

EXPORT_SYMBOL(drm_client_new);



/**

 * drm_client_release - Release DRM client resources

 * @client: DRM client

 *

 * Releases resources by closing the &drm_file that was opened by drm_client_new().

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



	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_DEV_DEBUG_KMS(dev->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_DEV_DEBUG_KMS(dev->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;



	if (buffer->vaddr && dev->driver->gem_prime_vunmap)

		dev->driver->gem_prime_vunmap(buffer->gem, buffer->vaddr);



	if (buffer->gem)

		drm_gem_object_put_unlocked(buffer->gem);



	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)

{

	struct drm_mode_create_dumb dumb_args = { };

	struct drm_device *dev = client->dev;

	struct drm_client_buffer *buffer;

	struct drm_gem_object *obj;

	void *vaddr;

	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_plane_cpp(format, 0) * 8;

	ret = drm_mode_create_dumb(dev, &dumb_args, client->file);

	if (ret)

		goto err_free;



	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;



	/*

	 * 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.

	 */

	vaddr = dev->driver->gem_prime_vmap(obj);

	if (!vaddr) {

		ret = -ENOMEM;

		goto err_delete;

	}



	buffer->vaddr = vaddr;



	return buffer;



err_delete:

	drm_client_buffer_delete(buffer);

err_free:

	kfree(buffer);



	return ERR_PTR(ret);

}



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_DEV_ERROR(buffer->client->dev->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 = info->cpp[0] * 8;

	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);

drivers/gpu/drm/drm_drv.c

+8 −0
Original line number Diff line number Diff line
@@ -34,6 +34,7 @@ 
#include <linux/slab.h>

#include <linux/srcu.h>



#include <drm/drm_client.h>

#include <drm/drm_drv.h>

#include <drm/drmP.h>
@@ -505,6 +506,8 @@ int drm_dev_init(struct drm_device *dev, 
	dev->driver = driver;



	INIT_LIST_HEAD(&dev->filelist);

	INIT_LIST_HEAD(&dev->filelist_internal);

	INIT_LIST_HEAD(&dev->clientlist);

	INIT_LIST_HEAD(&dev->ctxlist);

	INIT_LIST_HEAD(&dev->vmalist);

	INIT_LIST_HEAD(&dev->maplist);
@@ -514,6 +517,7 @@ int drm_dev_init(struct drm_device *dev, 
	spin_lock_init(&dev->event_lock);

	mutex_init(&dev->struct_mutex);

	mutex_init(&dev->filelist_mutex);

	mutex_init(&dev->clientlist_mutex);

	mutex_init(&dev->ctxlist_mutex);

	mutex_init(&dev->master_mutex);
@@ -569,6 +573,7 @@ int drm_dev_init(struct drm_device *dev, 
err_free:

	mutex_destroy(&dev->master_mutex);

	mutex_destroy(&dev->ctxlist_mutex);

	mutex_destroy(&dev->clientlist_mutex);

	mutex_destroy(&dev->filelist_mutex);

	mutex_destroy(&dev->struct_mutex);

	return ret;
@@ -603,6 +608,7 @@ void drm_dev_fini(struct drm_device *dev) 


	mutex_destroy(&dev->master_mutex);

	mutex_destroy(&dev->ctxlist_mutex);

	mutex_destroy(&dev->clientlist_mutex);

	mutex_destroy(&dev->filelist_mutex);

	mutex_destroy(&dev->struct_mutex);

	kfree(dev->unique);
@@ -858,6 +864,8 @@ void drm_dev_unregister(struct drm_device *dev) 


	dev->registered = false;



	drm_client_dev_unregister(dev);



	if (drm_core_check_feature(dev, DRIVER_MODESET))

		drm_modeset_unregister_all(dev);