hwmon: (pmbus/core) Use the new i2c_client debugfs directory

The I2C core now manages a debugfs directory per I2C client. PMBus has
its own debugfs hierarchy. Link the two, so a user will be pointed to
the I2C domain from the PMBus domain.

Suggested-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Reviewed-by: Tzung-Bi Shih <tzungbi@kernel.org>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

diff --git a/drivers/hwmon/pmbus/pmbus_core.c b/drivers/hwmon/pmbus/pmbus_core.c
index c0e657c36f24fe6b0d41ffa5bafcb925d07d88e6..c38072b6ee9884a20eae7007b0f0b2e5c6bf3e05 100644 (file)
--- a/drivers/hwmon/pmbus/pmbus_core.c
+++ b/drivers/hwmon/pmbus/pmbus_core.c
@@ -8,6 +8,7 @@
 
 #include <linux/debugfs.h>
 #include <linux/delay.h>
+#include <linux/dcache.h>
 #include <linux/kernel.h>
 #include <linux/math64.h>
 #include <linux/module.h>
@@ -99,7 +100,6 @@ struct pmbus_data {
        int num_attributes;
        struct attribute_group group;
        const struct attribute_group **groups;
-       struct dentry *debugfs;         /* debugfs device directory */
 
        struct pmbus_sensor *sensors;
 
@@ -3496,34 +3496,49 @@ static const struct file_operations pmbus_debugfs_ops_mfr = {
        .open = simple_open,
 };
 
-static void pmbus_remove_debugfs(void *data)
+static void pmbus_remove_symlink(void *symlink)
 {
-       struct dentry *entry = data;
-
-       debugfs_remove_recursive(entry);
+       debugfs_remove(symlink);
 }
 
 static int pmbus_init_debugfs(struct i2c_client *client,
                              struct pmbus_data *data)
 {
-       struct dentry *debugfs;
-       int i, idx = 0;
-       char name[PMBUS_NAME_SIZE];
+       struct dentry *symlink_d, *debugfs = client->debugfs;
        struct pmbus_debugfs_entry *entries;
+       const char *pathname, *symlink;
+       char name[PMBUS_NAME_SIZE];
+       int i, idx = 0;
 
-       if (!pmbus_debugfs_dir)
+       /*
+        * client->debugfs may be NULL or an ERR_PTR(). dentry_path_raw()
+        * does not check if its parameters are valid, so validate
+        * client->debugfs before using it.
+        */
+       if (!pmbus_debugfs_dir || IS_ERR_OR_NULL(debugfs))
                return -ENODEV;
 
        /*
-        * Create the debugfs directory for this device. Use the hwmon device
-        * name to avoid conflicts (hwmon numbers are globally unique).
+        * Backwards compatibility: Create symlink from /pmbus/<hwmon_device>
+        * to i2c debugfs directory.
         */
-       debugfs = debugfs_create_dir(dev_name(data->hwmon_dev),
-                                    pmbus_debugfs_dir);
-       if (IS_ERR_OR_NULL(debugfs))
-               return -ENODEV;
+       pathname = dentry_path_raw(debugfs, name, sizeof(name));
+       if (IS_ERR(pathname))
+               return PTR_ERR(pathname);
+
+       /*
+        * The path returned by dentry_path_raw() starts with '/'. Prepend it
+        * with ".." to get the symlink relative to the pmbus root directory.
+        */
+       symlink = kasprintf(GFP_KERNEL, "..%s", pathname);
+       if (!symlink)
+               return -ENOMEM;
+
+       symlink_d = debugfs_create_symlink(dev_name(data->hwmon_dev),
+                                          pmbus_debugfs_dir, symlink);
+       kfree(symlink);
 
-       data->debugfs = debugfs;
+       devm_add_action_or_reset(data->dev, pmbus_remove_symlink, symlink_d);
 
        /*
         * Allocate the max possible entries we need.
@@ -3711,9 +3726,7 @@ static int pmbus_init_debugfs(struct i2c_client *client,
                                            &pmbus_debugfs_ops);
                }
        }
-
-       return devm_add_action_or_reset(data->dev, pmbus_remove_debugfs,
-                                       debugfs);
+       return 0;
 }
 #else
 static int pmbus_init_debugfs(struct i2c_client *client,
@@ -3818,9 +3831,15 @@ EXPORT_SYMBOL_NS_GPL(pmbus_do_probe, "PMBUS");
 
 struct dentry *pmbus_get_debugfs_dir(struct i2c_client *client)
 {
-       struct pmbus_data *data = i2c_get_clientdata(client);
-
-       return data->debugfs;
+       /*
+        * client->debugfs may be an ERR_PTR(). Returning that to
+        * the calling code would potentially require additional
+        * complexity in the calling code and otherwise add no
+        * value. Return NULL in that case.
+        */
+       if (IS_ERR_OR_NULL(client->debugfs))
+               return NULL;
+       return client->debugfs;
 }
 EXPORT_SYMBOL_NS_GPL(pmbus_get_debugfs_dir, "PMBUS");