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-omap2/timer.c | 20 ++++---------------- 1 file changed, 4 insertions(+), 16 deletions(-) (limited to 'arch/arm/mach-omap2/timer.c') diff --git a/arch/arm/mach-omap2/timer.c b/arch/arm/mach-omap2/timer.c index 9edcd520510f..6eeff0e0ae01 100644 --- a/arch/arm/mach-omap2/timer.c +++ b/arch/arm/mach-omap2/timer.c @@ -254,7 +254,6 @@ static struct omap_dm_timer clksrc; /* * clocksource */ -static DEFINE_CLOCK_DATA(cd); static cycle_t clocksource_read_cycles(struct clocksource *cs) { return (cycle_t)__omap_dm_timer_read_counter(&clksrc, 1); @@ -268,23 +267,12 @@ static struct clocksource clocksource_gpt = { .flags = CLOCK_SOURCE_IS_CONTINUOUS, }; -static void notrace dmtimer_update_sched_clock(void) +static u32 notrace dmtimer_read_sched_clock(void) { - u32 cyc; - - cyc = __omap_dm_timer_read_counter(&clksrc, 1); - - update_sched_clock(&cd, cyc, (u32)~0); -} - -unsigned long long notrace sched_clock(void) -{ - u32 cyc = 0; - if (clksrc.reserved) - cyc = __omap_dm_timer_read_counter(&clksrc, 1); + return __omap_dm_timer_read_counter(clksrc.io_base, 1); - return cyc_to_sched_clock(&cd, cyc, (u32)~0); + return 0; } /* Setup free-running counter for clocksource */ @@ -301,7 +289,7 @@ static void __init omap2_gp_clocksource_init(int gptimer_id, __omap_dm_timer_load_start(&clksrc, OMAP_TIMER_CTRL_ST | OMAP_TIMER_CTRL_AR, 0, 1); - init_sched_clock(&cd, dmtimer_update_sched_clock, 32, clksrc.rate); + setup_sched_clock(dmtimer_read_sched_clock, 32, clksrc.rate); if (clocksource_register_hz(&clocksource_gpt, clksrc.rate)) pr_err("Could not register clocksource %s\n", -- cgit v1.2.3