diff options
| author | Marc Zyngier <Marc.Zyngier@arm.com> | 2011-12-15 12:19:23 +0100 |
|---|---|---|
| committer | Russell King <rmk+kernel@arm.linux.org.uk> | 2011-12-18 23:00:26 +0000 |
| commit | 2f0778afac79bd8d226225556858a636931eeabc (patch) | |
| tree | e00cea674f3d6cc8c5584aa5b75239f11f6d229d /arch/arm/plat-s5p | |
| parent | 3bdc3484e8f2b1b219ad0397d81ce4601fbaf76d (diff) | |
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 <kaloz@openwrt.org>
Cc: Eric Miao <eric.y.miao@gmail.com>
Cc: Colin Cross <ccross@android.com>
Cc: Erik Gilling <konkers@android.com>
Cc: Olof Johansson <olof@lixom.net>
Cc: Sascha Hauer <kernel@pengutronix.de>
Cc: Alessandro Rubini <rubini@unipv.it>
Cc: STEricsson <STEricsson_nomadik_linux@list.st.com>
Cc: Lennert Buytenhek <kernel@wantstofly.org>
Cc: Ben Dooks <ben-linux@fluff.org>
Tested-by: Jamie Iles <jamie@jamieiles.com>
Tested-by: Tony Lindgren <tony@atomide.com>
Tested-by: Kyungmin Park <kyungmin.park@samsung.com>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Nicolas Pitre <nico@linaro.org>
Acked-by: Krzysztof Halasa <khc@pm.waw.pl>
Acked-by: Kukjin Kim <kgene.kim@samsung.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Diffstat (limited to 'arch/arm/plat-s5p')
| -rw-r--r-- | arch/arm/plat-s5p/s5p-time.c | 19 |
1 files changed, 3 insertions, 16 deletions
diff --git a/arch/arm/plat-s5p/s5p-time.c b/arch/arm/plat-s5p/s5p-time.c index c833e7b5759..17c0a2c58df 100644 --- a/arch/arm/plat-s5p/s5p-time.c +++ b/arch/arm/plat-s5p/s5p-time.c @@ -10,7 +10,6 @@ * published by the Free Software Foundation. */ -#include <linux/sched.h> #include <linux/interrupt.h> #include <linux/irq.h> #include <linux/err.h> @@ -321,26 +320,14 @@ static void __iomem *s5p_timer_reg(void) * this wraps around for now, since it is just a relative time * stamp. (Inspired by U300 implementation.) */ -static DEFINE_CLOCK_DATA(cd); - -unsigned long long notrace sched_clock(void) +static u32 notrace s5p_read_sched_clock(void) { void __iomem *reg = s5p_timer_reg(); if (!reg) return 0; - return cyc_to_sched_clock(&cd, ~__raw_readl(reg), (u32)~0); -} - -static void notrace s5p_update_sched_clock(void) -{ - void __iomem *reg = s5p_timer_reg(); - - if (!reg) - return; - - update_sched_clock(&cd, ~__raw_readl(reg), (u32)~0); + return ~__raw_readl(reg); } static void __init s5p_clocksource_init(void) @@ -358,7 +345,7 @@ static void __init s5p_clocksource_init(void) s5p_time_setup(timer_source.source_id, TCNT_MAX); s5p_time_start(timer_source.source_id, PERIODIC); - init_sched_clock(&cd, s5p_update_sched_clock, 32, clock_rate); + setup_sched_clock(s5p_read_sched_clock, 32, clock_rate); if (clocksource_mmio_init(s5p_timer_reg(), "s5p_clocksource_timer", clock_rate, 250, 32, clocksource_mmio_readl_down)) |