From 2f0778afac79bd8d226225556858a636931eeabc Mon Sep 17 00:00:00 2001 From: Marc Zyngier Date: Thu, 15 Dec 2011 12:19:23 +0100 Subject: 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 Cc: Eric Miao Cc: Colin Cross Cc: Erik Gilling Cc: Olof Johansson Cc: Sascha Hauer Cc: Alessandro Rubini Cc: STEricsson Cc: Lennert Buytenhek Cc: Ben Dooks Tested-by: Jamie Iles Tested-by: Tony Lindgren Tested-by: Kyungmin Park Acked-by: Linus Walleij Acked-by: Nicolas Pitre Acked-by: Krzysztof Halasa Acked-by: Kukjin Kim Signed-off-by: Marc Zyngier Signed-off-by: Russell King --- arch/arm/mach-sa1100/time.c | 28 +++------------------------- 1 file changed, 3 insertions(+), 25 deletions(-) (limited to 'arch/arm/mach-sa1100') diff --git a/arch/arm/mach-sa1100/time.c b/arch/arm/mach-sa1100/time.c index fa6602491d54..1ee6d4ca8dd7 100644 --- a/arch/arm/mach-sa1100/time.c +++ b/arch/arm/mach-sa1100/time.c @@ -12,7 +12,6 @@ #include #include #include -#include /* just for sched_clock() - funny that */ #include #include @@ -20,29 +19,9 @@ #include #include -/* - * This is the SA11x0 sched_clock implementation. - */ -static DEFINE_CLOCK_DATA(cd); - -/* - * Constants generated by clocks_calc_mult_shift(m, s, 3.6864MHz, - * NSEC_PER_SEC, 60). - * This gives a resolution of about 271ns and a wrap period of about 19min. - */ -#define SC_MULT 2275555556u -#define SC_SHIFT 23 - -unsigned long long notrace sched_clock(void) -{ - u32 cyc = OSCR; - return cyc_to_fixed_sched_clock(&cd, cyc, (u32)~0, SC_MULT, SC_SHIFT); -} - -static void notrace sa1100_update_sched_clock(void) +static u32 notrace sa100_read_sched_clock(void) { - u32 cyc = OSCR; - update_sched_clock(&cd, cyc, (u32)~0); + return OSCR; } #define MIN_OSCR_DELTA 2 @@ -109,8 +88,7 @@ static void __init sa1100_timer_init(void) OIER = 0; OSSR = OSSR_M0 | OSSR_M1 | OSSR_M2 | OSSR_M3; - init_fixed_sched_clock(&cd, sa1100_update_sched_clock, 32, - 3686400, SC_MULT, SC_SHIFT); + setup_sched_clock(sa1100_read_sched_clock, 32, 3686400); clockevents_calc_mult_shift(&ckevt_sa1100_osmr0, 3686400, 4); ckevt_sa1100_osmr0.max_delta_ns = -- cgit v1.2.3