i2c: Multiplexed I2C bus core support

Add multiplexed bus core support. I2C multiplexer and switches
like pca954x get instantiated as new adapters per port.

Signed-off-by: Michael Lawnick <ml.lawnick@gmx.de>
Acked-by: Rodolfo Giometti <giometti@linux.it>
Signed-off-by: Jean Delvare <khali@linux-fr.org>

1 files changed, 8 insertions, 0 deletions

diff --git a/include/linux/i2c.h b/include/linux/i2c.h
index 798bad8741e4..4bae0b72ed3c 100644
--- a/include/linux/i2c.h
+++ b/include/linux/i2c.h
@@ -37,6 +37,7 @@
 #include <linux/of.h>           /* for struct device_node */
 
 extern struct bus_type i2c_bus_type;
+extern struct device_type i2c_adapter_type;
 
 /* --- General options ------------------------------------------------ */
 
@@ -383,6 +384,13 @@ static inline void i2c_set_adapdata(struct i2c_adapter *dev, void *data)
         dev_set_drvdata(&dev->dev, data);
 }
 
+static inline int i2c_parent_is_i2c_adapter(const struct i2c_adapter *adapter)
+{
+        return adapter->dev.parent != NULL
+                && adapter->dev.parent->bus == &i2c_bus_type
+                && adapter->dev.parent->type == &i2c_adapter_type;
+}
+
 /* Adapter locking functions, exported for shared pin cases */
 void i2c_lock_adapter(struct i2c_adapter *);
 void i2c_unlock_adapter(struct i2c_adapter *);