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authorMarc Zyngier <Marc.Zyngier@arm.com>2011-12-15 15:19:23 +0400
committerRussell King <rmk+kernel@arm.linux.org.uk>2011-12-19 03:00:26 +0400
commit2f0778afac79bd8d226225556858a636931eeabc (patch)
treee00cea674f3d6cc8c5584aa5b75239f11f6d229d /arch/arm/plat-nomadik
parent3bdc3484e8f2b1b219ad0397d81ce4601fbaf76d (diff)
downloadlinux-2f0778afac79bd8d226225556858a636931eeabc.tar.xz
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.c20
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);