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-tegra/timer.c | 24 +++--------------------- 1 file changed, 3 insertions(+), 21 deletions(-) (limited to 'arch/arm/mach-tegra/timer.c') diff --git a/arch/arm/mach-tegra/timer.c b/arch/arm/mach-tegra/timer.c index e2272d263a83..732c724008b1 100644 --- a/arch/arm/mach-tegra/timer.c +++ b/arch/arm/mach-tegra/timer.c @@ -19,7 +19,6 @@ #include #include -#include #include #include #include @@ -106,25 +105,9 @@ static struct clock_event_device tegra_clockevent = { .set_mode = tegra_timer_set_mode, }; -static DEFINE_CLOCK_DATA(cd); - -/* - * Constants generated by clocks_calc_mult_shift(m, s, 1MHz, NSEC_PER_SEC, 60). - * This gives a resolution of about 1us and a wrap period of about 1h11min. - */ -#define SC_MULT 4194304000u -#define SC_SHIFT 22 - -unsigned long long notrace sched_clock(void) -{ - u32 cyc = timer_readl(TIMERUS_CNTR_1US); - return cyc_to_fixed_sched_clock(&cd, cyc, (u32)~0, SC_MULT, SC_SHIFT); -} - -static void notrace tegra_update_sched_clock(void) +static u32 notrace tegra_read_sched_clock(void) { - u32 cyc = timer_readl(TIMERUS_CNTR_1US); - update_sched_clock(&cd, cyc, (u32)~0); + return timer_readl(TIMERUS_CNTR_1US); } /* @@ -218,8 +201,7 @@ static void __init tegra_init_timer(void) WARN(1, "Unknown clock rate"); } - init_fixed_sched_clock(&cd, tegra_update_sched_clock, 32, - 1000000, SC_MULT, SC_SHIFT); + setup_sched_clock(tegra_read_sched_clock, 32, 1000000); if (clocksource_mmio_init(timer_reg_base + TIMERUS_CNTR_1US, "timer_us", 1000000, 300, 32, clocksource_mmio_readl_up)) { -- cgit v1.2.3