Open/Close, File Operations and IOCTLs
======================================
-Open and Close
---------------
-
-Open and close handlers. None of those methods are mandatory::
-
- int (*firstopen) (struct drm_device *);
- void (*lastclose) (struct drm_device *);
- int (*open) (struct drm_device *, struct drm_file *);
- void (*preclose) (struct drm_device *, struct drm_file *);
- void (*postclose) (struct drm_device *, struct drm_file *);
-
-The firstopen method is called by the DRM core for legacy UMS (User Mode
-Setting) drivers only when an application opens a device that has no
-other opened file handle. UMS drivers can implement it to acquire device
-resources. KMS drivers can't use the method and must acquire resources
-in the load method instead.
-
-Similarly the lastclose method is called when the last application
-holding a file handle opened on the device closes it, for both UMS and
-KMS drivers. Additionally, the method is also called at module unload
-time or, for hot-pluggable devices, when the device is unplugged. The
-firstopen and lastclose calls can thus be unbalanced.
-
-The open method is called every time the device is opened by an
-application. Drivers can allocate per-file private data in this method
-and store them in the struct :c:type:`struct drm_file
-<drm_file>` driver_priv field. Note that the open method is
-called before firstopen.
-
-The close operation is split into preclose and postclose methods.
-Drivers must stop and cleanup all per-file operations in the preclose
-method. For instance pending vertical blanking and page flip events must
-be cancelled. No per-file operation is allowed on the file handle after
-returning from the preclose method.
-
-Finally the postclose method is called as the last step of the close
-operation, right before calling the lastclose method if no other open
-file handle exists for the device. Drivers that have allocated per-file
-private data in the open method should free it here.
-
-The lastclose method should restore CRTC and plane properties to default
-value, so that a subsequent open of the device will not inherit state
-from the previous user. It can also be used to execute delayed power
-switching state changes, e.g. in conjunction with the :ref:`vga_switcheroo`
-infrastructure. Beyond that KMS drivers should not do any
-further cleanup. Only legacy UMS drivers might need to clean up device
-state so that the vga console or an independent fbdev driver could take
-over.
-
File Operations
---------------
.. kernel-doc:: drivers/gpu/drm/drm_file.c
:doc: file operations
+.. kernel-doc:: include/drm/drm_file.h
+ :internal:
+
.. kernel-doc:: drivers/gpu/drm/drm_file.c
:export:
:doc: getunique and setversion story
+.. _drm_primary_node:
+
Primary Nodes, DRM Master and Authentication
============================================
for the same thing co-existing. If we add a few more complete mistakes into the
mix every year it would be entirely unmanageable.
+.. _drm_render_node:
+
Render nodes
============
*
* Drivers must define the file operations structure that forms the DRM
* userspace API entry point, even though most of those operations are
- * implemented in the DRM core. The mandatory functions are drm_open(),
+ * implemented in the DRM core. The resulting &struct file_operations must be
+ * stored in the &drm_driver.fops field. The mandatory functions are drm_open(),
* drm_read(), drm_ioctl() and drm_compat_ioctl() if CONFIG_COMPAT is enabled
- * (note that drm_compat_ioctl will be NULL if CONFIG_COMPAT=n). Drivers which
- * implement private ioctls that require 32/64 bit compatibility support must
- * provide their own .compat_ioctl() handler that processes private ioctls and
- * calls drm_compat_ioctl() for core ioctls.
+ * Note that drm_compat_ioctl will be NULL if CONFIG_COMPAT=n, so there's no
+ * need to sprinkle #ifdef into the code. Drivers which implement private ioctls
+ * that require 32/64 bit compatibility support must provide their own
+ * &file_operations.compat_ioctl handler that processes private ioctls and calls
+ * drm_compat_ioctl() for core ioctls.
*
* In addition drm_read() and drm_poll() provide support for DRM events. DRM
* events are a generic and extensible means to send asynchronous events to
* page flip completions by the KMS API. But drivers can also use it for their
* own needs, e.g. to signal completion of rendering.
*
+ * For the driver-side event interface see drm_event_reserve_init() and
+ * drm_send_event() as the main starting points.
+ *
* The memory mapping implementation will vary depending on how the driver
* manages memory. Legacy drivers will use the deprecated drm_legacy_mmap()
* function, modern drivers should use one of the provided memory-manager
- * specific implementations. For GEM-based drivers this is drm_gem_mmap().
+ * specific implementations. For GEM-based drivers this is drm_gem_mmap(), and
+ * for drivers which use the CMA GEM helpers it's drm_gem_cma_mmap().
*
* No other file operations are supported by the DRM userspace API. Overall the
* following is an example #file_operations structure::
* .llseek = no_llseek,
* .mmap = drm_gem_mmap,
* };
+ *
+ * FIXME: We should have a macro for this (and the CMA version) so that drivers
+ * don't have to repeat it all the time.
*/
static int drm_open_helper(struct file *filp, struct drm_minor *minor);
* @inode: device inode
* @filp: file pointer.
*
- * This function must be used by drivers as their .open() #file_operations
- * method. It looks up the correct DRM device and instantiates all the per-file
- * resources for it.
+ * This function must be used by drivers as their &file_operations.open method.
+ * It looks up the correct DRM device and instantiates all the per-file
+ * resources for it. It also calls the &drm_driver.open driver callback.
*
* RETURNS:
*
spin_unlock_irqrestore(&dev->event_lock, flags);
}
-/*
- * drm_legacy_dev_reinit
- *
- * Reinitializes a legacy/ums drm device in it's lastclose function.
- */
static void drm_legacy_dev_reinit(struct drm_device *dev)
{
if (dev->irq_enabled)
DRM_DEBUG("lastclose completed\n");
}
-/*
- * Take down the DRM device.
- *
- * \param dev DRM device structure.
- *
- * Frees every resource in \p dev.
- *
- * \sa drm_device
- */
void drm_lastclose(struct drm_device * dev)
{
DRM_DEBUG("\n");
* @inode: device inode
* @filp: file pointer.
*
- * This function must be used by drivers as their .release() #file_operations
- * method. It frees any resources associated with the open file, and if this is
- * the last open file for the DRM device also proceeds to call drm_lastclose().
+ * This function must be used by drivers as their &file_operations.release
+ * method. It frees any resources associated with the open file, and calls the
+ * &drm_driver.preclose and &drm_driver.lastclose driver callbacks. If this is
+ * the last open file for the DRM device also proceeds to call the
+ * &drm_driver.lastclose driver callback.
*
* RETURNS:
*
* @count: count in bytes to read
* @offset: offset to read
*
- * This function must be used by drivers as their .read() #file_operations
+ * This function must be used by drivers as their &file_operations.read
* method iff they use DRM events for asynchronous signalling to userspace.
* Since events are used by the KMS API for vblank and page flip completion this
* means all modern display drivers must use it.
*
- * @offset is ignore, DRM events are read like a pipe. Therefore drivers also
- * must set the .llseek() #file_operation to no_llseek(). Polling support is
+ * @offset is ignored, DRM events are read like a pipe. Therefore drivers also
+ * must set the &file_operation.llseek to no_llseek(). Polling support is
* provided by drm_poll().
*
* This function will only ever read a full event. Therefore userspace must
* @filp: file pointer
* @wait: poll waiter table
*
- * This function must be used by drivers as their .read() #file_operations
- * method iff they use DRM events for asynchronous signalling to userspace.
- * Since events are used by the KMS API for vblank and page flip completion this
- * means all modern display drivers must use it.
+ * This function must be used by drivers as their &file_operations.read method
+ * iff they use DRM events for asynchronous signalling to userspace. Since
+ * events are used by the KMS API for vblank and page flip completion this means
+ * all modern display drivers must use it.
*
* See also drm_read().
*
* @p: tracking structure for the pending event
*
* This function frees the event @p initialized with drm_event_reserve_init()
- * and releases any allocated space.
+ * and releases any allocated space. It is used to cancel an event when the
+ * nonblocking operation could not be submitted and needed to be aborted.
*/
void drm_event_cancel_free(struct drm_device *dev,
struct drm_pending_event *p)
* structure for GEM drivers.
*/
struct drm_driver {
-
/**
* @load:
*
* See drm_dev_init() and drm_dev_register() for proper and
* race-free way to set up a &struct drm_device.
*
+ * This is deprecated, do not use!
+ *
* Returns:
*
* Zero on success, non-zero value on failure.
*/
int (*load) (struct drm_device *, unsigned long flags);
+
+ /**
+ * @open:
+ *
+ * Driver callback when a new &struct drm_file is opened. Useful for
+ * setting up driver-private data structures like buffer allocators,
+ * execution contexts or similar things. Such driver-private resources
+ * must be released again in @postclose.
+ *
+ * Since the display/modeset side of DRM can only be owned by exactly
+ * one &struct drm_file (see &drm_file.is_master and &drm_device.master)
+ * there should never be a need to set up any modeset related resources
+ * in this callback. Doing so would be a driver design bug.
+ *
+ * Returns:
+ *
+ * 0 on success, a negative error code on failure, which will be
+ * promoted to userspace as the result of the open() system call.
+ */
int (*open) (struct drm_device *, struct drm_file *);
+
+ /**
+ * @preclose:
+ *
+ * One of the driver callbacks when a new &struct drm_file is closed.
+ * Useful for tearing down driver-private data structures allocated in
+ * @open like buffer allocators, execution contexts or similar things.
+ *
+ * Since the display/modeset side of DRM can only be owned by exactly
+ * one &struct drm_file (see &drm_file.is_master and &drm_device.master)
+ * there should never be a need to tear down any modeset related
+ * resources in this callback. Doing so would be a driver design bug.
+ *
+ * FIXME: It is not really clear why there's both @preclose and
+ * @postclose. Without a really good reason, use @postclose only.
+ */
void (*preclose) (struct drm_device *, struct drm_file *file_priv);
+
+ /**
+ * @postclose:
+ *
+ * One of the driver callbacks when a new &struct drm_file is closed.
+ * Useful for tearing down driver-private data structures allocated in
+ * @open like buffer allocators, execution contexts or similar things.
+ *
+ * Since the display/modeset side of DRM can only be owned by exactly
+ * one &struct drm_file (see &drm_file.is_master and &drm_device.master)
+ * there should never be a need to tear down any modeset related
+ * resources in this callback. Doing so would be a driver design bug.
+ *
+ * FIXME: It is not really clear why there's both @preclose and
+ * @postclose. Without a really good reason, use @postclose only.
+ */
void (*postclose) (struct drm_device *, struct drm_file *);
+
+ /**
+ * @lastclose:
+ *
+ * Called when the last &struct drm_file has been closed and there's
+ * currently no userspace client for the &struct drm_device.
+ *
+ * Modern drivers should only use this to force-restore the fbdev
+ * framebuffer using drm_fb_helper_restore_fbdev_mode_unlocked().
+ * Anything else would indicate there's something seriously wrong.
+ * Modern drivers can also use this to execute delayed power switching
+ * state changes, e.g. in conjunction with the :ref:`vga_switcheroo`
+ * infrastructure.
+ *
+ * This is called after @preclose and @postclose have been called.
+ *
+ * NOTE:
+ *
+ * All legacy drivers use this callback to de-initialize the hardware.
+ * This is purely because of the shadow-attach model, where the DRM
+ * kernel driver does not really own the hardware. Instead ownershipe is
+ * handled with the help of userspace through an inheritedly racy dance
+ * to set/unset the VT into raw mode.
+ *
+ * Legacy drivers initialize the hardware in the @firstopen callback,
+ * which isn't even called for modern drivers.
+ */
void (*lastclose) (struct drm_device *);
/**
* FIXME: Not sure we want to have drm_minor here in the end, but to avoid
* header include loops we need it here for now.
*/
+
enum drm_minor_type {
DRM_MINOR_PRIMARY,
DRM_MINOR_CONTROL,
};
/**
- * DRM minor structure. This structure represents a drm minor number.
+ * struct drm_minor - DRM device minor structure
+ *
+ * This structure represents a DRM minor number for device nodes in /dev.
+ * Entirely opaque to drivers and should never be inspected directly by drivers.
+ * Drivers instead should only interact with &struct drm_file and of course
+ * &struct drm_device, which is also where driver-private data and resources can
+ * be attached to.
*/
struct drm_minor {
- int index; /**< Minor device number */
- int type; /**< Control or render */
- struct device *kdev; /**< Linux device */
+ /* private: */
+ int index; /* Minor device number */
+ int type; /* Control or render */
+ struct device *kdev; /* Linux device */
struct drm_device *dev;
struct dentry *debugfs_root;
struct mutex debugfs_lock; /* Protects debugfs_list. */
};
-/* Event queued up for userspace to read */
+/**
+ * struct drm_pending_event - Event queued up for userspace to read
+ *
+ * This represents a DRM event. Drivers can use this as a generic completion
+ * mechanism, which supports kernel-internal &struct completion, &struct dma_fence
+ * and also the DRM-specific &struct drm_event delivery mechanism.
+ */
struct drm_pending_event {
+ /**
+ * @completion:
+ *
+ * Optional pointer to a kernel internal completion signalled when
+ * drm_send_event() is called, useful to internally synchronize with
+ * nonblocking operations.
+ */
struct completion *completion;
+
+ /**
+ * @completion_release:
+ *
+ * Optional callback currently only used by the atomic modeset helpers
+ * to clean up the reference count for the structure @completion is
+ * stored in.
+ */
void (*completion_release)(struct completion *completion);
+
+ /**
+ * @event:
+ *
+ * Pointer to the actual event that should be sent to userspace to be
+ * read using drm_read(). Can be optional, since nowadays events are
+ * also used to signal kernel internal threads with @completion or DMA
+ * transactions using @fence.
+ */
struct drm_event *event;
+
+ /**
+ * @fence:
+ *
+ * Optional DMA fence to unblock other hardware transactions which
+ * depend upon the nonblocking DRM operation this event represents.
+ */
struct dma_fence *fence;
+
+ /**
+ * @file_priv:
+ *
+ * &struct drm_file where @event should be delivered to. Only set when
+ * @event is set.
+ */
+ struct drm_file *file_priv;
+
+ /**
+ * @link:
+ *
+ * Double-linked list to keep track of this event. Can be used by the
+ * driver up to the point when it calls drm_send_event(), after that
+ * this list entry is owned by the core for its own book-keeping.
+ */
struct list_head link;
+
+ /**
+ * @pending_link:
+ *
+ * Entry on &drm_file.pending_event_list, to keep track of all pending
+ * events for @file_priv, to allow correct unwinding of them when
+ * userspace closes the file before the event is delivered.
+ */
struct list_head pending_link;
- struct drm_file *file_priv;
};
-/** File private data */
+/**
+ * struct drm_file - DRM file private data
+ *
+ * This structure tracks DRM state per open file descriptor.
+ */
struct drm_file {
+ /**
+ * @authenticated:
+ *
+ * Whether the client is allowed to submit rendering, which for legacy
+ * nodes means it must be authenticated.
+ *
+ * See also the :ref:`section on primary nodes and authentication
+ * <drm_primary_node>`.
+ */
unsigned authenticated :1;
- /* true when the client has asked us to expose stereo 3D mode flags */
+
+ /**
+ * @stereo_allowed:
+ *
+ * True when the client has asked us to expose stereo 3D mode flags.
+ */
unsigned stereo_allowed :1;
- /*
- * true if client understands CRTC primary planes and cursor planes
- * in the plane list
+
+ /**
+ * @universal_planes:
+ *
+ * True if client understands CRTC primary planes and cursor planes
+ * in the plane list. Automatically set when @atomic is set.
*/
unsigned universal_planes:1;
- /* true if client understands atomic properties */
+
+ /** @atomic: True if client understands atomic properties. */
unsigned atomic:1;
- /*
- * This client is the creator of @master.
- * Protected by struct drm_device::master_mutex.
+
+ /**
+ * @is_master:
+ *
+ * This client is the creator of @master. Protected by struct
+ * &drm_device.master_mutex.
+ *
+ * See also the :ref:`section on primary nodes and authentication
+ * <drm_primary_node>`.
*/
unsigned is_master:1;
+ /**
+ * @master:
+ *
+ * Master this node is currently associated with. Only relevant if
+ * drm_is_primary_client() returns true. Note that this only
+ * matches &drm_device.master if the master is the currently active one.
+ *
+ * See also @authentication and @is_master and the :ref:`section on
+ * primary nodes and authentication <drm_primary_node>`.
+ */
+ struct drm_master *master;
+
+ /** @pid: Process that opened this file. */
struct pid *pid;
+
+ /** @magic: Authentication magic, see @authenticated. */
drm_magic_t magic;
+
+ /**
+ * @lhead:
+ *
+ * List of all open files of a DRM device, linked into
+ * &drm_device.filelist. Protected by &drm_device.filelist_mutex.
+ */
struct list_head lhead;
+
+ /** @minor: &struct drm_minor for this file. */
struct drm_minor *minor;
- unsigned long lock_count;
- /** Mapping of mm object handles to object pointers. */
+ /**
+ * @object_idr:
+ *
+ * Mapping of mm object handles to object pointers. Used by the GEM
+ * subsystem. Protected by @table_lock.
+ */
struct idr object_idr;
- /** Lock for synchronization of access to object_idr. */
+
+ /** @table_lock: Protects @object_idr. */
spinlock_t table_lock;
+ /** @filp: Pointer to the core file structure. */
struct file *filp;
+
+ /**
+ * @driver_priv:
+ *
+ * Optional pointer for driver private data. Can be allocated in
+ * &drm_driver.open and should be freed in &drm_driver.postclose.
+ */
void *driver_priv;
- struct drm_master *master; /* master this node is currently associated with
- N.B. not always dev->master */
/**
- * fbs - List of framebuffers associated with this file.
+ * @fbs:
+ *
+ * List of &struct drm_framebuffer associated with this file, using the
+ * &drm_framebuffer.filp_head entry.
*
- * Protected by fbs_lock. Note that the fbs list holds a reference on
- * the fb object to prevent it from untimely disappearing.
+ * Protected by @fbs_lock. Note that the @fbs list holds a reference on
+ * the framebuffer object to prevent it from untimely disappearing.
*/
struct list_head fbs;
+
+ /** @fbs_lock: Protects @fbs. */
struct mutex fbs_lock;
- /** User-created blob properties; this retains a reference on the
- * property. */
+ /**
+ * @blobs:
+ *
+ * User-created blob properties; this retains a reference on the
+ * property.
+ *
+ * Protected by @drm_mode_config.blob_lock;
+ */
struct list_head blobs;
+ /** @event_wait: Waitqueue for new events added to @event_list. */
wait_queue_head_t event_wait;
+
+ /**
+ * @pending_event_list:
+ *
+ * List of pending &struct drm_pending_event, used to clean up pending
+ * events in case this file gets closed before the event is signalled.
+ * Uses the &drm_pending_event.pending_link entry.
+ *
+ * Protect by &drm_device.event_lock.
+ */
struct list_head pending_event_list;
+
+ /**
+ * @event_list:
+ *
+ * List of &struct drm_pending_event, ready for delivery to userspace
+ * through drm_read(). Uses the &drm_pending_event.link entry.
+ *
+ * Protect by &drm_device.event_lock.
+ */
struct list_head event_list;
+
+ /**
+ * @event_space:
+ *
+ * Available event space to prevent userspace from
+ * exhausting kernel memory. Currently limited to the fairly arbitrary
+ * value of 4KB.
+ */
int event_space;
+ /** @event_read_lock: Serializes drm_read(). */
struct mutex event_read_lock;
+ /**
+ * @prime:
+ *
+ * Per-file buffer caches used by the PRIME buffer sharing code.
+ */
struct drm_prime_file_private prime;
+
+ /* private: */
+ unsigned long lock_count; /* DRI1 legacy lock count */
};
+/**
+ * drm_is_primary_client - is this an open file of the primary node
+ * @file_priv: DRM file
+ *
+ * Returns true if this is an open file of the primary node, i.e.
+ * &drm_file.minor of @file_priv is a primary minor.
+ *
+ * See also the :ref:`section on primary nodes and authentication
+ * <drm_primary_node>`.
+ */
+static inline bool drm_is_primary_client(const struct drm_file *file_priv)
+{
+ return file_priv->minor->type == DRM_MINOR_PRIMARY;
+}
+
+/**
+ * drm_is_render_client - is this an open file of the render node
+ * @file_priv: DRM file
+ *
+ * Returns true if this is an open file of the render node, i.e.
+ * &drm_file.minor of @file_priv is a render minor.
+ *
+ * See also the :ref:`section on render nodes <drm_render_node>`.
+ */
static inline bool drm_is_render_client(const struct drm_file *file_priv)
{
return file_priv->minor->type == DRM_MINOR_RENDER;
}
+/**
+ * drm_is_control_client - is this an open file of the control node
+ * @file_priv: DRM file
+ *
+ * Control nodes are deprecated and in the process of getting removed from the
+ * DRM userspace API. Do not ever use!
+ */
static inline bool drm_is_control_client(const struct drm_file *file_priv)
{
return file_priv->minor->type == DRM_MINOR_CONTROL;
}
-static inline bool drm_is_primary_client(const struct drm_file *file_priv)
-{
- return file_priv->minor->type == DRM_MINOR_PRIMARY;
-}
-
int drm_open(struct inode *inode, struct file *filp);
ssize_t drm_read(struct file *filp, char __user *buffer,
size_t count, loff_t *offset);
projects / GitHub / LineageOS / android_kernel_motorola_exynos9610.git / commitdiff