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-nomadik | |
| 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-nomadik')
| -rw-r--r-- | arch/arm/plat-nomadik/timer.c | 20 |
1 files changed, 5 insertions, 15 deletions
diff --git a/arch/arm/plat-nomadik/timer.c b/arch/arm/plat-nomadik/timer.c index 30b6433d910d..ad1b45b605a4 100644 --- a/arch/arm/plat-nomadik/timer.c +++ b/arch/arm/plat-nomadik/timer.c @@ -17,7 +17,6 @@ #include <linux/clk.h> #include <linux/jiffies.h> #include <linux/err.h> -#include <linux/sched.h> #include <asm/mach/time.h> #include <asm/sched_clock.h> @@ -79,23 +78,12 @@ void __iomem *mtu_base; /* Assigned by machine code */ * local implementation which uses the clocksource to get some * better resolution when scheduling the kernel. */ -static DEFINE_CLOCK_DATA(cd); - -unsigned long long notrace sched_clock(void) +static u32 notrace nomadik_read_sched_clock(void) { - u32 cyc; - if (unlikely(!mtu_base)) return 0; - cyc = -readl(mtu_base + MTU_VAL(0)); - return cyc_to_sched_clock(&cd, cyc, (u32)~0); -} - -static void notrace nomadik_update_sched_clock(void) -{ - u32 cyc = -readl(mtu_base + MTU_VAL(0)); - update_sched_clock(&cd, cyc, (u32)~0); + return -readl(mtu_base + MTU_VAL(0)); } #endif @@ -231,9 +219,11 @@ void __init nmdk_timer_init(void) rate, 200, 32, clocksource_mmio_readl_down)) pr_err("timer: failed to initialize clock source %s\n", "mtu_0"); + #ifdef CONFIG_NOMADIK_MTU_SCHED_CLOCK - init_sched_clock(&cd, nomadik_update_sched_clock, 32, rate); + setup_sched_clock(nomadik_read_sched_clock, 32, rate); #endif + /* Timer 1 is used for events */ clockevents_calc_mult_shift(&nmdk_clkevt, rate, MTU_MIN_RANGE); |