[PATCH v7 4/4] i2c: Add i2c_device_get_match_data() callback

[Biju Das <biju.das.jz@xxxxxxxxxxxxxx>]

Add i2c_device_get_match_data() callback to struct bus_type.

While at it, introduced i2c_get_match_data_helper() to avoid code
duplication with i2c_get_match_data().

Suggested-by: Dmitry Torokhov <dmitry.torokhov@xxxxxxxxx>
Suggested-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
Signed-off-by: Biju Das <biju.das.jz@xxxxxxxxxxxxxx>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
---
v6->v7:
 * Updated typo in commit description struct bus_type()->struct bus_type.
 * Added Rb tag from Andy.
v5->v6:
 * Merged with patch#3 from v5.
 * Separate patch#3 to prepare for better difference for
   i2c_match_id() changes.
v4->v5:
 * Added const struct device_driver variable 'drv' in i2c_device_get_match
   _data().
 * For code readability and maintenance perspective, added separate NULL
   check for drv and client variable and added comment for NULL check for
   drv variable.
v3->v4:
 * Dropped struct i2c_driver parameter from i2c_get_match_data_helper()
 * Split I2C sysfs handling in separate patch.
v2->v3:
 * Extended to support i2c_of_match_device() as suggested by Andy.
 * Changed i2c_of_match_device_sysfs() as non-static function as it is
   needed for i2c_device_get_match_data().
 * Added a TODO comment to use i2c_verify_client() when it accepts const
   pointer.
 * Added multiple returns to make code path for device_get_match_data()
   faster in i2c_get_match_data().
RFC v1->v2:
 * Replaced "Signed-off-by"->"Suggested-by" tag for Dmitry.
 * Fixed build warnings reported by kernel test robot <lkp@xxxxxxxxx>
 * Added const qualifier to return type and parameter struct i2c_driver
   in i2c_get_match_data_helper().
 * Added const qualifier to struct i2c_driver in i2c_get_match_data()
 * Dropped driver variable from i2c_device_get_match_data()
 * Replaced to_i2c_client with logic for assigning verify_client as it
   returns non const pointer.
---
 drivers/i2c/i2c-core-base.c | 53 ++++++++++++++++++++++++++++++++-----
 1 file changed, 47 insertions(+), 6 deletions(-)

diff --git a/drivers/i2c/i2c-core-base.c b/drivers/i2c/i2c-core-base.c
index 7005dfe64066..d543460e47c2 100644
--- a/drivers/i2c/i2c-core-base.c
+++ b/drivers/i2c/i2c-core-base.c
@@ -114,15 +114,10 @@ const struct i2c_device_id *i2c_match_id(const struct i2c_device_id *id,
 }
 EXPORT_SYMBOL_GPL(i2c_match_id);
 
-const void *i2c_get_match_data(const struct i2c_client *client)
+static const void *i2c_get_match_data_helper(const struct i2c_client *client)
 {
 	const struct i2c_driver *driver = to_i2c_driver(client->dev.driver);
 	const struct i2c_device_id *match;
-	const void *data;
-
-	data = device_get_match_data(&client->dev);
-	if (data)
-		return data;
 
 	match = i2c_match_id(driver->id_table, client);
 	if (!match)
@@ -130,6 +125,51 @@ const void *i2c_get_match_data(const struct i2c_client *client)
 
 	return (const void *)match->driver_data;
 }
+
+static const void *i2c_device_get_match_data(const struct device *dev)
+{
+	const struct device_driver *drv = dev->driver;
+	const struct i2c_client *client;
+	const void *data;
+
+	/*
+	 * It is not guaranteed that the function is always called on a device
+	 * bound to a driver (even though we normally expect this to be the
+	 * case).
+	 */
+	if (!drv)
+		return NULL;
+
+	/* TODO: use i2c_verify_client() when it accepts const pointer */
+	client = (dev->type == &i2c_client_type) ? to_i2c_client(dev) : NULL;
+	if (!client)
+		return NULL;
+
+	data = i2c_get_match_data_helper(client);
+	if (data)
+		return data;
+
+	if (drv->of_match_table) {
+		const struct of_device_id *match;
+
+		match = i2c_of_match_device_sysfs(drv->of_match_table, client);
+		if (match)
+			return match->data;
+	}
+
+	return NULL;
+}
+
+const void *i2c_get_match_data(const struct i2c_client *client)
+{
+	const void *data;
+
+	data = device_get_match_data(&client->dev);
+	if (data)
+		return data;
+
+	return i2c_get_match_data_helper(client);
+}
 EXPORT_SYMBOL(i2c_get_match_data);
 
 static int i2c_device_match(struct device *dev, struct device_driver *drv)
@@ -694,6 +734,7 @@ struct bus_type i2c_bus_type = {
 	.probe		= i2c_device_probe,
 	.remove		= i2c_device_remove,
 	.shutdown	= i2c_device_shutdown,
+	.get_match_data	= i2c_device_get_match_data,
 };
 EXPORT_SYMBOL_GPL(i2c_bus_type);
 
-- 
2.25.1