ARM: 7205/2: sched_clock: allow sched_clock to be selected at runtime

sched_clock() is yet another blocker on the road to the single
image. This patch implements an idea by Russell King:

http://www.spinics.net/lists/linux-omap/msg49561.html

Instead of asking the platform to implement both sched_clock()
itself and the rollover callback, simply register a read()
function, and let the ARM code care about sched_clock() itself,
the conversion to ns and the rollover. sched_clock() uses
this read() function as an indirection to the platform code.
If the platform doesn't provide a read(), the code falls back
to the jiffy counter (just like the default sched_clock).

This allow some simplifications and possibly some footprint gain
when multiple platforms are compiled in. Among the drawbacks,
the removal of the *_fixed_sched_clock optimization which could
negatively impact some platforms (sa1100, tegra, versatile
and omap).

Tested on 11MPCore, OMAP4 and Tegra.

Cc: Imre Kaloz <[email protected]>
Cc: Eric Miao <[email protected]>
Cc: Colin Cross <[email protected]>
Cc: Erik Gilling <[email protected]>
Cc: Olof Johansson <[email protected]>
Cc: Sascha Hauer <[email protected]>
Cc: Alessandro Rubini <[email protected]>
Cc: STEricsson <[email protected]>
Cc: Lennert Buytenhek <[email protected]>
Cc: Ben Dooks <[email protected]>
Tested-by: Jamie Iles <[email protected]>
Tested-by: Tony Lindgren <[email protected]>
Tested-by: Kyungmin Park <[email protected]>
Acked-by: Linus Walleij <[email protected]>
Acked-by: Nicolas Pitre <[email protected]>
Acked-by: Krzysztof Halasa <[email protected]>
Acked-by: Kukjin Kim <[email protected]>
Signed-off-by: Marc Zyngier <[email protected]>
Signed-off-by: Russell King <[email protected]>

0 files changed, 0 insertions, 0 deletions