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// SPDX-License-Identifier: GPL-2.0
/*
* (C) COPYRIGHT 2016 ARM Limited. All rights reserved.
* Author: Brian Starkey <brian.starkey@arm.com>
*
* This program is free software and is provided to you under the terms of the
* GNU General Public License version 2 as published by the Free Software
* Foundation, and any use by you of this program is subject to the terms
* of such GNU licence.
*/
#include <drm/drm_crtc.h>
#include <drm/drm_modeset_helper_vtables.h>
#include <drm/drm_property.h>
#include <drm/drm_writeback.h>
#include <drm/drmP.h>
/**
* DOC: overview
*
* Writeback connectors are used to expose hardware which can write the output
* from a CRTC to a memory buffer. They are used and act similarly to other
* types of connectors, with some important differences:
* - Writeback connectors don't provide a way to output visually to the user.
* - Writeback connectors should always report as "disconnected" (so that
* clients which don't understand them will ignore them).
* - Writeback connectors don't have EDID.
*
* A framebuffer may only be attached to a writeback connector when the
* connector is attached to a CRTC. The WRITEBACK_FB_ID property which sets the
* framebuffer applies only to a single commit (see below). A framebuffer may
* not be attached while the CRTC is off.
*
* Writeback connectors have some additional properties, which userspace
* can use to query and control them:
*
* "WRITEBACK_FB_ID":
* Write-only object property storing a DRM_MODE_OBJECT_FB: it stores the
* framebuffer to be written by the writeback connector. This property is
* similar to the FB_ID property on planes, but will always read as zero
* and is not preserved across commits.
* Userspace must set this property to an output buffer every time it
* wishes the buffer to get filled.
*
* "WRITEBACK_PIXEL_FORMATS":
* Immutable blob property to store the supported pixel formats table. The
* data is an array of u32 DRM_FORMAT_* fourcc values.
* Userspace can use this blob to find out what pixel formats are supported
* by the connector's writeback engine.
*/
static int create_writeback_properties(struct drm_device *dev)
{
struct drm_property *prop;
if (!dev->mode_config.writeback_fb_id_property) {
prop = drm_property_create_object(dev, DRM_MODE_PROP_ATOMIC,
"WRITEBACK_FB_ID",
DRM_MODE_OBJECT_FB);
if (!prop)
return -ENOMEM;
dev->mode_config.writeback_fb_id_property = prop;
}
if (!dev->mode_config.writeback_pixel_formats_property) {
prop = drm_property_create(dev, DRM_MODE_PROP_BLOB |
DRM_MODE_PROP_ATOMIC |
DRM_MODE_PROP_IMMUTABLE,
"WRITEBACK_PIXEL_FORMATS", 0);
if (!prop)
return -ENOMEM;
dev->mode_config.writeback_pixel_formats_property = prop;
}
return 0;
}
static const struct drm_encoder_funcs drm_writeback_encoder_funcs = {
.destroy = drm_encoder_cleanup,
};
/**
* drm_writeback_connector_init - Initialize a writeback connector and its properties
* @dev: DRM device
* @wb_connector: Writeback connector to initialize
* @con_funcs: Connector funcs vtable
* @enc_helper_funcs: Encoder helper funcs vtable to be used by the internal encoder
* @formats: Array of supported pixel formats for the writeback engine
* @n_formats: Length of the formats array
*
* This function creates the writeback-connector-specific properties if they
* have not been already created, initializes the connector as
* type DRM_MODE_CONNECTOR_WRITEBACK, and correctly initializes the property
* values. It will also create an internal encoder associated with the
* drm_writeback_connector and set it to use the @enc_helper_funcs vtable for
* the encoder helper.
*
* Drivers should always use this function instead of drm_connector_init() to
* set up writeback connectors.
*
* Returns: 0 on success, or a negative error code
*/
int drm_writeback_connector_init(struct drm_device *dev,
struct drm_writeback_connector *wb_connector,
const struct drm_connector_funcs *con_funcs,
const struct drm_encoder_helper_funcs *enc_helper_funcs,
const u32 *formats, int n_formats)
{
struct drm_property_blob *blob;
struct drm_connector *connector = &wb_connector->base;
struct drm_mode_config *config = &dev->mode_config;
int ret = create_writeback_properties(dev);
if (ret != 0)
return ret;
blob = drm_property_create_blob(dev, n_formats * sizeof(*formats),
formats);
if (IS_ERR(blob))
return PTR_ERR(blob);
drm_encoder_helper_add(&wb_connector->encoder, enc_helper_funcs);
ret = drm_encoder_init(dev, &wb_connector->encoder,
&drm_writeback_encoder_funcs,
DRM_MODE_ENCODER_VIRTUAL, NULL);
if (ret)
goto fail;
connector->interlace_allowed = 0;
ret = drm_connector_init(dev, connector, con_funcs,
DRM_MODE_CONNECTOR_WRITEBACK);
if (ret)
goto connector_fail;
ret = drm_mode_connector_attach_encoder(connector,
&wb_connector->encoder);
if (ret)
goto attach_fail;
INIT_LIST_HEAD(&wb_connector->job_queue);
spin_lock_init(&wb_connector->job_lock);
drm_object_attach_property(&connector->base,
config->writeback_fb_id_property, 0);
drm_object_attach_property(&connector->base,
config->writeback_pixel_formats_property,
blob->base.id);
wb_connector->pixel_formats_blob_ptr = blob;
return 0;
attach_fail:
drm_connector_cleanup(connector);
connector_fail:
drm_encoder_cleanup(&wb_connector->encoder);
fail:
drm_property_blob_put(blob);
return ret;
}
EXPORT_SYMBOL(drm_writeback_connector_init);
/**
* drm_writeback_queue_job - Queue a writeback job for later signalling
* @wb_connector: The writeback connector to queue a job on
* @job: The job to queue
*
* This function adds a job to the job_queue for a writeback connector. It
* should be considered to take ownership of the writeback job, and so any other
* references to the job must be cleared after calling this function.
*
* Drivers must ensure that for a given writeback connector, jobs are queued in
* exactly the same order as they will be completed by the hardware (and
* signaled via drm_writeback_signal_completion).
*
* For every call to drm_writeback_queue_job() there must be exactly one call to
* drm_writeback_signal_completion()
*
* See also: drm_writeback_signal_completion()
*/
void drm_writeback_queue_job(struct drm_writeback_connector *wb_connector,
struct drm_writeback_job *job)
{
unsigned long flags;
spin_lock_irqsave(&wb_connector->job_lock, flags);
list_add_tail(&job->list_entry, &wb_connector->job_queue);
spin_unlock_irqrestore(&wb_connector->job_lock, flags);
}
EXPORT_SYMBOL(drm_writeback_queue_job);
/*
* @cleanup_work: deferred cleanup of a writeback job
*
* The job cannot be cleaned up directly in drm_writeback_signal_completion,
* because it may be called in interrupt context. Dropping the framebuffer
* reference can sleep, and so the cleanup is deferred to a workqueue.
*/
static void cleanup_work(struct work_struct *work)
{
struct drm_writeback_job *job = container_of(work,
struct drm_writeback_job,
cleanup_work);
drm_framebuffer_put(job->fb);
kfree(job);
}
/**
* drm_writeback_signal_completion - Signal the completion of a writeback job
* @wb_connector: The writeback connector whose job is complete
*
* Drivers should call this to signal the completion of a previously queued
* writeback job. It should be called as soon as possible after the hardware
* has finished writing, and may be called from interrupt context.
* It is the driver's responsibility to ensure that for a given connector, the
* hardware completes writeback jobs in the same order as they are queued.
*
* Unless the driver is holding its own reference to the framebuffer, it must
* not be accessed after calling this function.
*
* See also: drm_writeback_queue_job()
*/
void
drm_writeback_signal_completion(struct drm_writeback_connector *wb_connector)
{
unsigned long flags;
struct drm_writeback_job *job;
spin_lock_irqsave(&wb_connector->job_lock, flags);
job = list_first_entry_or_null(&wb_connector->job_queue,
struct drm_writeback_job,
list_entry);
if (job)
list_del(&job->list_entry);
spin_unlock_irqrestore(&wb_connector->job_lock, flags);
if (WARN_ON(!job))
return;
INIT_WORK(&job->cleanup_work, cleanup_work);
queue_work(system_long_wq, &job->cleanup_work);
}
EXPORT_SYMBOL(drm_writeback_signal_completion);
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