[RFC 2/3] drm: Register drmfs filesystem from drm init

[swati.dhingra@intel.com]

From: Swati Dhingra <swati.dhingra@intel.com>

During drm module initialization, drm_core_init initializes the drmfs
filesystem and register this with kernel. A driver specific directory is created
inside drmfs root, and dentry of this directory is saved for subsequent use
by the driver (e.g. i915). The driver can then create files/directories inside
this root directory directly.
In case of i915 driver, the top directory is created at '/sys/kernel/drm/i915'.

Signed-off-by: Sourab Gupta <sourab.gupta@intel.com>
Signed-off-by: Swati Dhingra <swati.dhingra@intel.com>
---
 drivers/gpu/drm/drm_drv.c | 22 ++++++++++++++++++++++
 include/drm/drm_drv.h     |  3 +++
 2 files changed, 25 insertions(+)

diff --git a/drivers/gpu/drm/drm_drv.c b/drivers/gpu/drm/drm_drv.c
index 84fcfcb..ead360bd 100644
--- a/drivers/gpu/drm/drm_drv.c
+++ b/drivers/gpu/drm/drm_drv.c
@@ -688,6 +688,14 @@ int drm_dev_register(struct drm_device *dev, unsigned long flags)
 {
 	int ret;
 
+#ifdef CONFIG_DRMFS
+	dev->driver->drmfs_root = drmfs_create_dir(dev->driver->name, NULL);
+	if (IS_ERR(dev->driver->drmfs_root)) {
+		DRM_ERROR("Failed to get drmfs root dentry\n");
+		return PTR_ERR(dev->driver->drmfs_root);
+	}
+#endif
+
 	mutex_lock(&drm_global_mutex);
 
 	ret = drm_minor_register(dev, DRM_MINOR_CONTROL);
@@ -758,6 +766,9 @@ void drm_dev_unregister(struct drm_device *dev)
 	drm_minor_unregister(dev, DRM_MINOR_PRIMARY);
 	drm_minor_unregister(dev, DRM_MINOR_RENDER);
 	drm_minor_unregister(dev, DRM_MINOR_CONTROL);
+#ifdef CONFIG_DRMFS
+	drmfs_remove(dev->driver->drmfs_root);
+#endif
 }
 EXPORT_SYMBOL(drm_dev_unregister);
 
@@ -825,6 +836,9 @@ static void drm_core_exit(void)
 {
 	unregister_chrdev(DRM_MAJOR, "drm");
 	debugfs_remove(drm_debugfs_root);
+#ifdef CONFIG_DRMFS
+	drmfs_fini();
+#endif
 	drm_sysfs_destroy();
 	idr_destroy(&drm_minors_idr);
 	drm_connector_ida_destroy();
@@ -845,6 +859,14 @@ static int __init drm_core_init(void)
 		goto error;
 	}
 
+#ifdef CONFIG_DRMFS
+	ret = drmfs_init();
+	if (ret < 0) {
+		DRM_ERROR("Cannot create DRM FS: %d\n", ret);
+		goto error;
+	}
+#endif
+
 	drm_debugfs_root = debugfs_create_dir("dri", NULL);
 	if (!drm_debugfs_root) {
 		ret = -ENOMEM;
diff --git a/include/drm/drm_drv.h b/include/drm/drm_drv.h
index aad8bba..34804de 100644
--- a/include/drm/drm_drv.h
+++ b/include/drm/drm_drv.h
@@ -403,6 +403,9 @@ struct drm_driver {
 
 	/* List of devices hanging off this driver with stealth attach. */
 	struct list_head legacy_dev_list;
+
+	/* drmfs parent directory dentry for this driver */
+	struct dentry *drmfs_root;
 };
 
 extern __printf(6, 7)
-- 
2.7.4

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