Using Mini UART on RPI CM

Martin Sperl kernel at
Wed Sep 30 23:59:45 PDT 2015

> On 30.09.2015, at 22:18, Eric Anholt <eric at> wrote:
>> Did i miss something in my board dts file to enable the aux uart clock?
> That branch looks like it needs the submitted version of "Add a driver
> for the auxiliary peripheral clock gates" instead, which I think would
> fix this problem.

That is my guess as well - and yes, that patch requires the clock-patch
of Eric to be installed - I wish it was there already!

If you need a hacky solution have a user-space program to set registers
0x20215004 directly (via mmap) to 0x1 and then it should also work...

As for the official driver - as per Stephen, I will need to write a wrapper
driver around 8250 instantiating the driver with the “patched” clocks.
But I am waiting for the clocks and spiaux to go in first...


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