1 files changed, 16 insertions, 2 deletions

diff --git a/include/linux/i2c.h b/include/linux/i2c.h
index eff50e062be8..deddeb8c337c 100644
--- a/include/linux/i2c.h
+++ b/include/linux/i2c.h
@@ -342,11 +342,25 @@ i2c_register_board_info(int busnum, struct i2c_board_info const *info,
 }
 #endif /* I2C_BOARDINFO */
 
-/*
+/**
+ * struct i2c_algorithm - represent I2C transfer method
+ * @master_xfer: Issue a set of i2c transactions to the given I2C adapter
+ *   defined by the msgs array, with num messages available to transfer via
+ *   the adapter specified by adap.
+ * @smbus_xfer: Issue smbus transactions to the given I2C adapter. If this
+ *   is not present, then the bus layer will try and convert the SMBus calls
+ *   into I2C transfers instead.
+ * @functionality: Return the flags that this algorithm/adapter pair supports
+ *   from the I2C_FUNC_* flags.
+ *
  * The following structs are for those who like to implement new bus drivers:
  * i2c_algorithm is the interface to a class of hardware solutions which can
  * be addressed using the same bus algorithms - i.e. bit-banging or the PCF8584
  * to name two of the most common.
+ *
+ * The return codes from the @master_xfer field should indicate the type of
+ * error code that occured during the transfer, as documented in the kernel
+ * Documentation file Documentation/i2c/fault-codes.
  */
 struct i2c_algorithm {
         /* If an adapter algorithm can't do I2C-level access, set master_xfer
@@ -445,7 +459,7 @@ static inline void i2c_set_adapdata(struct i2c_adapter *dev, void *data)
 static inline struct i2c_adapter *
 i2c_parent_is_i2c_adapter(const struct i2c_adapter *adapter)
 {
-#if IS_ENABLED(I2C_MUX)
+#if IS_ENABLED(CONFIG_I2C_MUX)
         struct device *parent = adapter->dev.parent;
 
         if (parent != NULL && parent->type == &i2c_adapter_type)