drm: Document device unplug infrastructure

While at it, also ocd and give them a consistent drm_dev_ prefix, like
the other device instance functionality. Plus move the functions into
the right places.
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20170802115604.12734-3-daniel.vetter@ffwll.ch

drivers/gpu/drm/drm_drv.c

@@ -291,7 +291,7 @@ struct drm_minor *drm_minor_acquire(unsigned int minor_id)
 
 	if (!minor) {
 		return ERR_PTR(-ENODEV);
-	} else if (drm_device_is_unplugged(minor->dev)) {
+	} else if (drm_dev_is_unplugged(minor->dev)) {
 		drm_dev_unref(minor->dev);
 		return ERR_PTR(-ENODEV);
 	}
@@ -364,7 +364,22 @@ void drm_put_dev(struct drm_device *dev)
 }
 EXPORT_SYMBOL(drm_put_dev);
 
-void drm_unplug_dev(struct drm_device *dev)
+static void drm_device_set_unplugged(struct drm_device *dev)
+{
+	smp_wmb();
+	atomic_set(&dev->unplugged, 1);
+}
+
+/**
+ * drm_dev_unplug - unplug a DRM device
+ * @dev: DRM device
+ *
+ * This unplugs a hotpluggable DRM device, which makes it inaccessible to
+ * userspace operations. Entry-points can use drm_dev_is_unplugged(). This
+ * essentially unregisters the device like drm_dev_unregister(), but can be
+ * called while there are still open users of @dev.
+ */
+void drm_dev_unplug(struct drm_device *dev)
 {
 	/* for a USB device */
 	if (drm_core_check_feature(dev, DRIVER_MODESET))
@@ -383,7 +398,7 @@ void drm_unplug_dev(struct drm_device *dev)
 	}
 	mutex_unlock(&drm_global_mutex);
 }
-EXPORT_SYMBOL(drm_unplug_dev);
+EXPORT_SYMBOL(drm_dev_unplug);
 
 /*
  * DRM internal mount
@@ -835,6 +850,9 @@ EXPORT_SYMBOL(drm_dev_register);
  * drm_dev_register() but does not deallocate the device. The caller must call
  * drm_dev_unref() to drop their final reference.
  *
+ * A special form of unregistering for hotpluggable devices is drm_dev_unplug(),
+ * which can be called while there are still open users of @dev.
+ *
  * This should be called first in the device teardown code to make sure
  * userspace can't access the device instance any more.
  */

drivers/gpu/drm/drm_file.c

@@ -436,7 +436,7 @@ int drm_release(struct inode *inode, struct file *filp)
 
 	if (!--dev->open_count) {
 		drm_lastclose(dev);
-		if (drm_device_is_unplugged(dev))
+		if (drm_dev_is_unplugged(dev))
 			drm_put_dev(dev);
 	}
 	mutex_unlock(&drm_global_mutex);

drivers/gpu/drm/drm_gem.c

@@ -1001,7 +1001,7 @@ int drm_gem_mmap(struct file *filp, struct vm_area_struct *vma)
 	struct drm_vma_offset_node *node;
 	int ret;
 
-	if (drm_device_is_unplugged(dev))
+	if (drm_dev_is_unplugged(dev))
 		return -ENODEV;
 
 	drm_vma_offset_lock_lookup(dev->vma_offset_manager);

drivers/gpu/drm/drm_gem_cma_helper.c

@@ -390,7 +390,7 @@ unsigned long drm_gem_cma_get_unmapped_area(struct file *filp,
 	struct drm_device *dev = priv->minor->dev;
 	struct drm_vma_offset_node *node;
 
-	if (drm_device_is_unplugged(dev))
+	if (drm_dev_is_unplugged(dev))
 		return -ENODEV;
 
 	drm_vma_offset_lock_lookup(dev->vma_offset_manager);

drivers/gpu/drm/drm_ioctl.c

@@ -716,7 +716,7 @@ long drm_ioctl_kernel(struct file *file, drm_ioctl_t *func, void *kdata,
 	struct drm_device *dev = file_priv->minor->dev;
 	int retcode;
 
-	if (drm_device_is_unplugged(dev))
+	if (drm_dev_is_unplugged(dev))
 		return -ENODEV;
 
 	retcode = drm_ioctl_permit(flags, file_priv);
@@ -765,7 +765,7 @@ long drm_ioctl(struct file *filp,
 
 	dev = file_priv->minor->dev;
 
-	if (drm_device_is_unplugged(dev))
+	if (drm_dev_is_unplugged(dev))
 		return -ENODEV;
 
 	is_driver_ioctl = nr >= DRM_COMMAND_BASE && nr < DRM_COMMAND_END;

drivers/gpu/drm/drm_vm.c

@@ -631,7 +631,7 @@ int drm_legacy_mmap(struct file *filp, struct vm_area_struct *vma)
 	struct drm_device *dev = priv->minor->dev;
 	int ret;
 
-	if (drm_device_is_unplugged(dev))
+	if (drm_dev_is_unplugged(dev))
 		return -ENODEV;
 
 	mutex_lock(&dev->struct_mutex);

drivers/gpu/drm/tinydrm/core/tinydrm-pipe.c

@@ -56,7 +56,7 @@ static const struct drm_connector_helper_funcs tinydrm_connector_hfuncs = {
 static enum drm_connector_status
 tinydrm_connector_detect(struct drm_connector *connector, bool force)
 {
-	if (drm_device_is_unplugged(connector->dev))
+	if (drm_dev_is_unplugged(connector->dev))
 		return connector_status_disconnected;
 
 	return connector->status;

drivers/gpu/drm/udl/udl_connector.c

@@ -96,7 +96,7 @@ static int udl_mode_valid(struct drm_connector *connector,
 static enum drm_connector_status
 udl_detect(struct drm_connector *connector, bool force)
 {
-	if (drm_device_is_unplugged(connector->dev))
+	if (drm_dev_is_unplugged(connector->dev))
 		return connector_status_disconnected;
 	return connector_status_connected;
 }

drivers/gpu/drm/udl/udl_drv.c

@@ -102,7 +102,7 @@ static void udl_usb_disconnect(struct usb_interface *interface)
 	drm_kms_helper_poll_disable(dev);
 	udl_fbdev_unplug(dev);
 	udl_drop_usb(dev);
-	drm_unplug_dev(dev);
+	drm_dev_unplug(dev);
 }
 
 /*

drivers/gpu/drm/udl/udl_fb.c

@@ -198,7 +198,7 @@ static int udl_fb_open(struct fb_info *info, int user)
 	struct udl_device *udl = dev->dev_private;
 
 	/* If the USB device is gone, we don't accept new opens */
-	if (drm_device_is_unplugged(udl->ddev))
+	if (drm_dev_is_unplugged(udl->ddev))
 		return -ENODEV;
 
 	ufbdev->fb_count++;

include/drm/drmP.h

@@ -320,19 +320,6 @@ static __inline__ int drm_core_check_feature(struct drm_device *dev,
 	return ((dev->driver->driver_features & feature) ? 1 : 0);
 }
 
-static inline void drm_device_set_unplugged(struct drm_device *dev)
-{
-	smp_wmb();
-	atomic_set(&dev->unplugged, 1);
-}
-
-static inline int drm_device_is_unplugged(struct drm_device *dev)
-{
-	int ret = atomic_read(&dev->unplugged);
-	smp_rmb();
-	return ret;
-}
-
 /******************************************************************/
 /** \name Internal function definitions */
 /*@{*/

include/drm/drm_drv.h

@@ -30,7 +30,8 @@
 #include <linux/list.h>
 #include <linux/irqreturn.h>
 
-struct drm_device;
+#include <drm/drm_device.h>
+
 struct drm_file;
 struct drm_gem_object;
 struct drm_master;
@@ -613,7 +614,24 @@ void drm_dev_unregister(struct drm_device *dev);
 void drm_dev_ref(struct drm_device *dev);
 void drm_dev_unref(struct drm_device *dev);
 void drm_put_dev(struct drm_device *dev);
-void drm_unplug_dev(struct drm_device *dev);
+void drm_dev_unplug(struct drm_device *dev);
+
+/**
+ * drm_dev_is_unplugged - is a DRM device unplugged
+ * @dev: DRM device
+ *
+ * This function can be called to check whether a hotpluggable is unplugged.
+ * Unplugging itself is singalled through drm_dev_unplug(). If a device is
+ * unplugged, these two functions guarantee that any store before calling
+ * drm_dev_unplug() is visible to callers of this function after it completes
+ */
+static inline int drm_dev_is_unplugged(struct drm_device *dev)
+{
+	int ret = atomic_read(&dev->unplugged);
+	smp_rmb();
+	return ret;
+}
+
 
 int drm_dev_set_unique(struct drm_device *dev, const char *name);