Hi, On 21/03/2017 at 13:08:54 -0500, Tracy Smith wrote: > Hi, not sure if this is the correct venue to post a question, so > please forgive and direct me to the correct board or list if not. >
Lee is probably not the one to ask :) > A custom board implementation using a ARM-8 Cortex A53 NXP LS1043ardb > is considering moving the RTC from the control board to an FPGA. > Reason is for accuracy of time/date and efficiency for their FPGA/DSP > application. > > 1) What kernel changes would be required to support such an > implementation and these would need to be pushed to the community > under the GPL? > You'll have to write a proper driver. It will have to be licensed under the GPLv2 but you don't necessarily have to push it anywhere (that is not how the GPL is working). > 2) Is it a trivial task to make such changes in the kernel to support > an RTC not located on the control board/SoC itself? > RTC drivers are not so complicated. I'd say that the difficulty mainly depends on how the SoC can access the FPGA. > 3) What is the expected behavior of the kernel with no changes added > to accommodate such an architecture? > The kernel will work, the RTC is not required. > 4) Is there a configurable kernel option to allow for such a change, > or have these or similar changes already been added to the kernel? > More details are needed to answer that but basically if your FPGa emulates an RTC that is already supported, you don't need to write much. -- Alexandre Belloni, Free Electrons Embedded Linux and Kernel engineering http://free-electrons.com
