Where can I find the kernel sources for Altera SoCs?

I’d like to build the Linux kernel on my own, but I can’t find the kernel sources. Where can I download the source files?

The sources are available on [GitHub][1]. [1]: http://www.github.com/altera-opensource

Note that each GSRD release also includes complete instructions on how to build everything, including getting the sources. Here is [an example][2]. [2]: http://www.rocketboards.org/foswiki/view/Documentation/A10GSRDV1501CompilingLinuxKernel

please can you tell me how can i boot the FreeRTOS on SD card for DE1 Soc cyclone V board??