[PATCH 2/4] i2c: addition of client reg/unreg callbacks

[Alain Volmat <alain.volmat@st.com>]

Addition of two callbacks reg_client and unreg_client that can be
implemented by adapter drivers in order to take action whenever a
client is being registered to it.

Signed-off-by: Alain Volmat <alain.volmat@st.com>
---
 drivers/i2c/i2c-core-base.c | 11 +++++++++++
 include/linux/i2c.h         |  6 ++++++
 2 files changed, 17 insertions(+)

diff --git a/drivers/i2c/i2c-core-base.c b/drivers/i2c/i2c-core-base.c
index 2e4560671183..4c84c6264314 100644
--- a/drivers/i2c/i2c-core-base.c
+++ b/drivers/i2c/i2c-core-base.c
@@ -319,6 +319,12 @@ static int i2c_device_probe(struct device *dev)
 	if (!client)
 		return 0;
 
+	if (client->adapter->algo->reg_client) {
+		status = client->adapter->algo->reg_client(client);
+		if (status)
+			return status;
+	}
+
 	driver = to_i2c_driver(dev->driver);
 
 	client->irq = client->init_irq;
@@ -417,6 +423,8 @@ static int i2c_device_probe(struct device *dev)
 put_sync_adapter:
 	if (client->flags & I2C_CLIENT_HOST_NOTIFY)
 		pm_runtime_put_sync(&client->adapter->dev);
+	if (client->adapter->algo->reg_client)
+		client->adapter->algo->unreg_client(client);
 
 	return status;
 }
@@ -445,6 +453,9 @@ static int i2c_device_remove(struct device *dev)
 	if (client->flags & I2C_CLIENT_HOST_NOTIFY)
 		pm_runtime_put(&client->adapter->dev);
 
+	if (client->adapter->algo->unreg_client)
+		client->adapter->algo->unreg_client(client);
+
 	return status;
 }
 
diff --git a/include/linux/i2c.h b/include/linux/i2c.h
index 45d36ba4826b..61b838caf454 100644
--- a/include/linux/i2c.h
+++ b/include/linux/i2c.h
@@ -509,6 +509,8 @@ i2c_register_board_info(int busnum, struct i2c_board_info const *info,
  *   so e.g. PMICs can be accessed very late before shutdown. Optional.
  * @functionality: Return the flags that this algorithm/adapter pair supports
  *   from the ``I2C_FUNC_*`` flags.
+ * @reg_client: Callback informing that a new client is being registered
+ * @unreg_client: Callback informing that a client is being removed
  * @reg_slave: Register given client to I2C slave mode of this adapter
  * @unreg_slave: Unregister given client from I2C slave mode of this adapter
  *
@@ -545,6 +547,10 @@ struct i2c_algorithm {
 	/* To determine what the adapter supports */
 	u32 (*functionality)(struct i2c_adapter *adap);
 
+	/* To inform the adapter of the probe/remove of a client */
+	int (*reg_client)(struct i2c_client *client);
+	void (*unreg_client)(struct i2c_client *client);
+
 #if IS_ENABLED(CONFIG_I2C_SLAVE)
 	int (*reg_slave)(struct i2c_client *client);
 	int (*unreg_slave)(struct i2c_client *client);
-- 
2.17.1