The driver model supports two ways for passing device parameters;
Device Tree and platform_data (board file).
Each driver should generally support both of them because some
popular IPs are used on various platforms.
Assume the following scenario:
- The driver Foo is used on SoC Bar and SoC Baz
- The SoC Bar uses Device Tree control (CONFIG_OF_CONTROL=y)
- The SoC Baz does not support Device Tree; uses a board file
In this situation, the device driver Foo should work with/without
the device tree control. The driver should have .of_match and
.ofdata_to_platdata members for SoC Bar, while they are meaningless
for SoC Baz; therefore those device-tree control code should go
inside #ifdef CONFIG_OF_CONTROL.