phy: core: add debugfs files

Add a debugfs root for phy class, and create a debugfs directory under
the root when create phy, then phy drivers can add debugfs files.

Signed-off-by: Chunfeng Yun <chunfeng.yun@mediatek.com>
Link: https://lore.kernel.org/r/20230513092218.21139-1-chunfeng.yun@mediatek.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>

Author: Chunfeng Yun

drivers/phy/phy-core.c

@@ -11,6 +11,7 @@
 #include <linux/export.h>
 #include <linux/module.h>
 #include <linux/err.h>
+#include <linux/debugfs.h>
 #include <linux/device.h>
 #include <linux/slab.h>
 #include <linux/of.h>
@@ -20,6 +21,7 @@
 #include <linux/regulator/consumer.h>
 
 static struct class *phy_class;
+static struct dentry *phy_debugfs_root;
 static DEFINE_MUTEX(phy_provider_mutex);
 static LIST_HEAD(phy_provider_list);
 static LIST_HEAD(phys);
@@ -996,6 +998,8 @@ struct phy *phy_create(struct device *dev, struct device_node *node,
 		pm_runtime_no_callbacks(&phy->dev);
 	}
 
+	phy->debugfs = debugfs_create_dir(dev_name(&phy->dev), phy_debugfs_root);
+
 	return phy;
 
 put_dev:
@@ -1226,6 +1230,7 @@ static void phy_release(struct device *dev)
 
 	phy = to_phy(dev);
 	dev_vdbg(dev, "releasing '%s'\n", dev_name(dev));
+	debugfs_remove_recursive(phy->debugfs);
 	regulator_put(phy->pwr);
 	ida_simple_remove(&phy_ida, phy->id);
 	kfree(phy);
@@ -1242,6 +1247,15 @@ static int __init phy_core_init(void)
 
 	phy_class->dev_release = phy_release;
 
+	phy_debugfs_root = debugfs_create_dir("phy", NULL);
+
 	return 0;
 }
 device_initcall(phy_core_init);
+
+static void __exit phy_core_exit(void)
+{
+	debugfs_remove_recursive(phy_debugfs_root);
+	class_destroy(phy_class);
+}
+module_exit(phy_core_exit);

include/linux/phy/phy.h

@@ -148,6 +148,7 @@ struct phy_attrs {
  * @power_count: used to protect when the PHY is used by multiple consumers
  * @attrs: used to specify PHY specific attributes
  * @pwr: power regulator associated with the phy
+ * @debugfs: debugfs directory
  */
 struct phy {
 	struct device		dev;
@@ -158,6 +159,7 @@ struct phy {
 	int			power_count;
 	struct phy_attrs	attrs;
 	struct regulator	*pwr;
+	struct dentry		*debugfs;
 };
 
 /**