Clock framework implementation for TI H4 OMAP2420 development board

["Juha Keski-Saari" <juha.keski-saari%teleca.com@localhost>]

Hello everyone

We'd like to publish a clock framework implementation which we have
been using in development for more than half a year, so you can
consider it tested R&D grade code even though coverage hasn't been a
full 100%.

We began the implementation to satisfy a need for centralized
peripheral clock state control on the TI H4 OMAP2420 board we were
using. We found a reference implementation from Linux Maemo code for
the same hardware platform, yet what exists today is barely
recognisable as having similar roots. Most of the remaining
similarities spur from the technical reference manual instructions of
the HW and are thus unavoidable. Later on we extended the
implementation to also support clock operating point transitions, which
we used to fulfill basic Frequency Scaling functions on the hardware.
DPLL and SDRC reprogramming was not in our scope but could be easily
implemented inside this framework. We believe this can be helpful to
anyone involved with arm-based hardware, to accelerate development of
features that require manipulation or information on system clocks for
operation.

We wish to publish this code under the copyright of the NetBSD
foundation, so it can be useful in any way is seen fit. We welcome all
nature of discussion regarding this component. Below you can find a
link to the patch formatted on top of netbsd-current dated Sep 9th.

http://koowaldah.org/people/ash/netbsd/clock_framework.patch

Regards,
Juha Keski-Saari