</sect2>
<sect2>
<title>File Operations</title>
- <synopsis>const struct file_operations *fops</synopsis>
- <abstract>File operations for the DRM device node.</abstract>
- <para>
- 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 <methodname>open</methodname>,
- <methodname>release</methodname> and <methodname>ioctl</methodname>
- operations are handled by
- <programlisting>
- .owner = THIS_MODULE,
- .open = drm_open,
- .release = drm_release,
- .unlocked_ioctl = drm_ioctl,
- #ifdef CONFIG_COMPAT
- .compat_ioctl = drm_compat_ioctl,
- #endif
- </programlisting>
- </para>
- <para>
- Drivers that implement private ioctls that requires 32/64bit
- compatibility support must provide their own
- <methodname>compat_ioctl</methodname> handler that processes private
- ioctls and calls <function>drm_compat_ioctl</function> for core ioctls.
- </para>
- <para>
- The <methodname>read</methodname> and <methodname>poll</methodname>
- operations provide support for reading DRM events and polling them. They
- are implemented by
- <programlisting>
- .poll = drm_poll,
- .read = drm_read,
- .llseek = no_llseek,
- </programlisting>
- </para>
- <para>
- The memory mapping implementation varies depending on how the driver
- manages memory. Pre-GEM drivers will use <function>drm_mmap</function>,
- while GEM-aware drivers will use <function>drm_gem_mmap</function>. See
- <xref linkend="drm-gem"/>.
- <programlisting>
- .mmap = drm_gem_mmap,
- </programlisting>
- </para>
- <para>
- No other file operation is supported by the DRM API.
- </para>
+!Pdrivers/gpu/drm/drm_fops.c file operations
+!Edrivers/gpu/drm/drm_fops.c
</sect2>
<sect2>
<title>IOCTLs</title>
-/**
+/*
* \file drm_fops.c
* File operations for DRM
*
/* from BKL pushdown */
DEFINE_MUTEX(drm_global_mutex);
+/**
+ * DOC: file operations
+ *
+ * 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(),
+ * drm_read(), drm_ioctl() and drm_compat_ioctl if CONFIG_COMPAT is enabled.
+ * Drivers which implement private ioctls that require 32/64 bit compatibility
+ * support must provided their onw .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
+ * userspace through the file descriptor. They are used to send vblank event and
+ * page flip completions by the KMS API. But drivers can also use it for their
+ * own needs, e.g. to signal completion of rendering.
+ *
+ * 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().
+ *
+ * No other file operations are supported by the DRM userspace API. Overall the
+ * following is an example #file_operations structure:
+ *
+ * static const example_drm_fops = {
+ * .owner = THIS_MODULE,
+ * .open = drm_open,
+ * .release = drm_release,
+ * .unlocked_ioctl = drm_ioctl,
+ * #ifdef CONFIG_COMPAT
+ * .compat_ioctl = drm_compat_ioctl,
+ * #endif
+ * .poll = drm_poll,
+ * .read = drm_read,
+ * .llseek = no_llseek,
+ * .mmap = drm_gem_mmap,
+ * };
+ */
+
static int drm_open_helper(struct file *filp, struct drm_minor *minor);
static int drm_setup(struct drm_device * dev)
}
/**
- * Open file.
+ * drm_open - open method for DRM file
+ * @inode: device inode
+ * @filp: file pointer.
*
- * \param inode device inode
- * \param filp file pointer.
- * \return zero on success or a negative number on failure.
+ * 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.
+ *
+ * RETURNS:
*
- * Searches the DRM device with the same minor number, calls open_helper(), and
- * increments the device open count. If the open count was previous at zero,
- * i.e., it's the first that the device is open, then calls setup().
+ * 0 on success or negative errno value on falure.
*/
int drm_open(struct inode *inode, struct file *filp)
{
}
EXPORT_SYMBOL(drm_open);
-/**
+/*
* Check whether DRI will run on this CPU.
*
* \return non-zero if the DRI will run on this CPU, or zero otherwise.
return 1;
}
-/**
+/*
* drm_new_set_master - Allocate a new master object and become master for the
* associated master realm.
*
return ret;
}
-/**
+/*
* Called whenever a process opens /dev/drm.
*
* \param filp file pointer.
spin_unlock_irqrestore(&dev->event_lock, flags);
}
-/**
+/*
* drm_legacy_dev_reinit
*
* Reinitializes a legacy/ums drm device in it's lastclose function.
dev->if_version = 0;
}
-/**
+/*
* Take down the DRM device.
*
* \param dev DRM device structure.
}
/**
- * Release file.
+ * drm_release - release method for DRM file
+ * @inode: device inode
+ * @filp: file pointer.
*
- * \param inode device inode
- * \param file_priv DRM file private.
- * \return zero on success or a negative number on failure.
+ * 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().
*
- * If the hardware lock is held then free it, and take it again for the kernel
- * context since it's necessary to reclaim buffers. Unlink the file private
- * data from its list and free it. Decreases the open count and if it reaches
- * zero calls drm_lastclose().
+ * RETURNS:
+ *
+ * Always succeeds and returns 0.
*/
int drm_release(struct inode *inode, struct file *filp)
{
if (file_priv->is_master) {
struct drm_master *master = file_priv->master;
- /**
+ /*
* Since the master is disappearing, so is the
* possibility to lock.
*/
}
EXPORT_SYMBOL(drm_release);
+/**
+ * drm_read - read method for DRM file
+ * @filp: file pointer
+ * @buffer: userspace destination pointer for the read
+ * @count: count in bytes to read
+ * @offset: offset to read
+ *
+ * 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.
+ *
+ * @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
+ * provided by drm_poll().
+ *
+ * This function will only ever read a full event. Therefore userspace must
+ * supply a big enough buffer to fit any event to ensure forward progress. Since
+ * the maximum event space is currently 4K it's recommended to just use that for
+ * safety.
+ *
+ * RETURNS:
+ *
+ * Number of bytes read (always aligned to full events, and can be 0) or a
+ * negative error code on failure.
+ */
ssize_t drm_read(struct file *filp, char __user *buffer,
size_t count, loff_t *offset)
{
}
EXPORT_SYMBOL(drm_read);
+/**
+ * drm_poll - poll method for DRM file
+ * @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.
+ *
+ * See also drm_read().
+ *
+ * RETURNS:
+ *
+ * Mask of POLL flags indicating the current status of the file.
+ */
unsigned int drm_poll(struct file *filp, struct poll_table_struct *wait)
{
struct drm_file *file_priv = filp->private_data;
unsigned int cmd, unsigned long arg);
extern bool drm_ioctl_flags(unsigned int nr, unsigned int *flags);
- /* Device support (drm_fops.h) */
-extern int drm_open(struct inode *inode, struct file *filp);
-extern ssize_t drm_read(struct file *filp, char __user *buffer,
- size_t count, loff_t *offset);
-extern int drm_release(struct inode *inode, struct file *filp);
-extern int drm_new_set_master(struct drm_device *dev, struct drm_file *fpriv);
-
- /* Mapping support (drm_vm.h) */
-extern unsigned int drm_poll(struct file *filp, struct poll_table_struct *wait);
+/* File Operations (drm_fops.c) */
+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);
+int drm_release(struct inode *inode, struct file *filp);
+int drm_new_set_master(struct drm_device *dev, struct drm_file *fpriv);
+
+unsigned int drm_poll(struct file *filp, struct poll_table_struct *wait);
/* Misc. IOCTL support (drm_ioctl.c) */
int drm_noop(struct drm_device *dev, void *data,
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