1 files changed, 200 insertions, 6 deletions

diff --git a/drivers/gpu/drm/drm_drv.c b/drivers/gpu/drm/drm_drv.c
index 381581b01d48..50d849d1bc6e 100644
--- a/drivers/gpu/drm/drm_drv.c
+++ b/drivers/gpu/drm/drm_drv.c
@@ -286,6 +286,138 @@ void drm_minor_release(struct drm_minor *minor)
  * Note that the lifetime rules for &drm_device instance has still a lot of
  * historical baggage. Hence use the reference counting provided by
  * drm_dev_get() and drm_dev_put() only carefully.
+ *
+ * Display driver example
+ * ~~~~~~~~~~~~~~~~~~~~~~
+ *
+ * The following example shows a typical structure of a DRM display driver.
+ * The example focus on the probe() function and the other functions that is
+ * almost always present and serves as a demonstration of devm_drm_dev_init()
+ * usage with its accompanying drm_driver->release callback.
+ *
+ * .. code-block:: c
+ *
+ *	struct driver_device {
+ *		struct drm_device drm;
+ *		void *userspace_facing;
+ *		struct clk *pclk;
+ *	};
+ *
+ *	static void driver_drm_release(struct drm_device *drm)
+ *	{
+ *		struct driver_device *priv = container_of(...);
+ *
+ *		drm_mode_config_cleanup(drm);
+ *		drm_dev_fini(drm);
+ *		kfree(priv->userspace_facing);
+ *		kfree(priv);
+ *	}
+ *
+ *	static struct drm_driver driver_drm_driver = {
+ *		[...]
+ *		.release = driver_drm_release,
+ *	};
+ *
+ *	static int driver_probe(struct platform_device *pdev)
+ *	{
+ *		struct driver_device *priv;
+ *		struct drm_device *drm;
+ *		int ret;
+ *
+ *		[
+ *		  devm_kzalloc() can't be used here because the drm_device
+ *		  lifetime can exceed the device lifetime if driver unbind
+ *		  happens when userspace still has open file descriptors.
+ *		]
+ *		priv = kzalloc(sizeof(*priv), GFP_KERNEL);
+ *		if (!priv)
+ *			return -ENOMEM;
+ *
+ *		drm = &priv->drm;
+ *
+ *		ret = devm_drm_dev_init(&pdev->dev, drm, &driver_drm_driver);
+ *		if (ret) {
+ *			kfree(drm);
+ *			return ret;
+ *		}
+ *
+ *		drm_mode_config_init(drm);
+ *
+ *		priv->userspace_facing = kzalloc(..., GFP_KERNEL);
+ *		if (!priv->userspace_facing)
+ *			return -ENOMEM;
+ *
+ *		priv->pclk = devm_clk_get(dev, "PCLK");
+ *		if (IS_ERR(priv->pclk))
+ *			return PTR_ERR(priv->pclk);
+ *
+ *		[ Further setup, display pipeline etc ]
+ *
+ *		platform_set_drvdata(pdev, drm);
+ *
+ *		drm_mode_config_reset(drm);
+ *
+ *		ret = drm_dev_register(drm);
+ *		if (ret)
+ *			return ret;
+ *
+ *		drm_fbdev_generic_setup(drm, 32);
+ *
+ *		return 0;
+ *	}
+ *
+ *	[ This function is called before the devm_ resources are released ]
+ *	static int driver_remove(struct platform_device *pdev)
+ *	{
+ *		struct drm_device *drm = platform_get_drvdata(pdev);
+ *
+ *		drm_dev_unregister(drm);
+ *		drm_atomic_helper_shutdown(drm)
+ *
+ *		return 0;
+ *	}
+ *
+ *	[ This function is called on kernel restart and shutdown ]
+ *	static void driver_shutdown(struct platform_device *pdev)
+ *	{
+ *		drm_atomic_helper_shutdown(platform_get_drvdata(pdev));
+ *	}
+ *
+ *	static int __maybe_unused driver_pm_suspend(struct device *dev)
+ *	{
+ *		return drm_mode_config_helper_suspend(dev_get_drvdata(dev));
+ *	}
+ *
+ *	static int __maybe_unused driver_pm_resume(struct device *dev)
+ *	{
+ *		drm_mode_config_helper_resume(dev_get_drvdata(dev));
+ *
+ *		return 0;
+ *	}
+ *
+ *	static const struct dev_pm_ops driver_pm_ops = {
+ *		SET_SYSTEM_SLEEP_PM_OPS(driver_pm_suspend, driver_pm_resume)
+ *	};
+ *
+ *	static struct platform_driver driver_driver = {
+ *		.driver = {
+ *			[...]
+ *			.pm = &driver_pm_ops,
+ *		},
+ *		.probe = driver_probe,
+ *		.remove = driver_remove,
+ *		.shutdown = driver_shutdown,
+ *	};
+ *	module_platform_driver(driver_driver);
+ *
+ * Drivers that want to support device unplugging (USB, DT overlay unload) should
+ * use drm_dev_unplug() instead of drm_dev_unregister(). The driver must protect
+ * regions that is accessing device resources to prevent use after they're
+ * released. This is done using drm_dev_enter() and drm_dev_exit(). There is one
+ * shortcoming however, drm_dev_unplug() marks the drm_device as unplugged before
+ * drm_atomic_helper_shutdown() is called. This means that if the disable code
+ * paths are protected, they will not run on regular driver module unload,
+ * possibily leaving the hardware enabled.
  */
 
 /**
@@ -376,11 +508,6 @@ void drm_dev_unplug(struct drm_device *dev)
 	synchronize_srcu(&drm_unplug_srcu);
 
 	drm_dev_unregister(dev);
-
-	mutex_lock(&drm_global_mutex);
-	if (dev->open_count == 0)
-		drm_dev_put(dev);
-	mutex_unlock(&drm_global_mutex);
 }
 EXPORT_SYMBOL(drm_dev_unplug);
 
@@ -457,6 +584,31 @@ static void drm_fs_inode_free(struct inode *inode)
 }
 
 /**
+ * DOC: component helper usage recommendations
+ *
+ * DRM drivers that drive hardware where a logical device consists of a pile of
+ * independent hardware blocks are recommended to use the :ref:`component helper
+ * library<component>`. For consistency and better options for code reuse the
+ * following guidelines apply:
+ *
+ *  - The entire device initialization procedure should be run from the
+ *    &component_master_ops.master_bind callback, starting with drm_dev_init(),
+ *    then binding all components with component_bind_all() and finishing with
+ *    drm_dev_register().
+ *
+ *  - The opaque pointer passed to all components through component_bind_all()
+ *    should point at &struct drm_device of the device instance, not some driver
+ *    specific private structure.
+ *
+ *  - The component helper fills the niche where further standardization of
+ *    interfaces is not practical. When there already is, or will be, a
+ *    standardized interface like &drm_bridge or &drm_panel, providing its own
+ *    functions to find such components at driver load time, like
+ *    drm_of_find_panel_or_bridge(), then the component helper should not be
+ *    used.
+ */
+
+/**
  * drm_dev_init - Initialise new DRM device
  * @dev: DRM device
  * @driver: DRM driver
@@ -501,7 +653,7 @@ int drm_dev_init(struct drm_device *dev,
 	BUG_ON(!parent);
 
 	kref_init(&dev->ref);
-	dev->dev = parent;
+	dev->dev = get_device(parent);
 	dev->driver = driver;
 
 	/* no per-device feature limits by default */
@@ -571,6 +723,7 @@ err_minors:
 	drm_minor_free(dev, DRM_MINOR_RENDER);
 	drm_fs_inode_free(dev->anon_inode);
 err_free:
+	put_device(dev->dev);
 	mutex_destroy(&dev->master_mutex);
 	mutex_destroy(&dev->ctxlist_mutex);
 	mutex_destroy(&dev->clientlist_mutex);
@@ -580,6 +733,45 @@ err_free:
 }
 EXPORT_SYMBOL(drm_dev_init);
 
+static void devm_drm_dev_init_release(void *data)
+{
+	drm_dev_put(data);
+}
+
+/**
+ * devm_drm_dev_init - Resource managed drm_dev_init()
+ * @parent: Parent device object
+ * @dev: DRM device
+ * @driver: DRM driver
+ *
+ * Managed drm_dev_init(). The DRM device initialized with this function is
+ * automatically put on driver detach using drm_dev_put(). You must supply a
+ * &drm_driver.release callback to control the finalization explicitly.
+ *
+ * RETURNS:
+ * 0 on success, or error code on failure.
+ */
+int devm_drm_dev_init(struct device *parent,
+		      struct drm_device *dev,
+		      struct drm_driver *driver)
+{
+	int ret;
+
+	if (WARN_ON(!parent || !driver->release))
+		return -EINVAL;
+
+	ret = drm_dev_init(dev, driver, parent);
+	if (ret)
+		return ret;
+
+	ret = devm_add_action(parent, devm_drm_dev_init_release, dev);
+	if (ret)
+		devm_drm_dev_init_release(dev);
+
+	return ret;
+}
+EXPORT_SYMBOL(devm_drm_dev_init);
+
 /**
  * drm_dev_fini - Finalize a dead DRM device
  * @dev: DRM device
@@ -606,6 +798,8 @@ void drm_dev_fini(struct drm_device *dev)
 	drm_minor_free(dev, DRM_MINOR_PRIMARY);
 	drm_minor_free(dev, DRM_MINOR_RENDER);
 
+	put_device(dev->dev);
+
 	mutex_destroy(&dev->master_mutex);
 	mutex_destroy(&dev->ctxlist_mutex);
 	mutex_destroy(&dev->clientlist_mutex);