diff options
author | Marc Zyngier <Marc.Zyngier@arm.com> | 2011-12-15 06:19:23 -0500 |
---|---|---|
committer | Russell King <rmk+kernel@arm.linux.org.uk> | 2011-12-18 18:00:26 -0500 |
commit | 2f0778afac79bd8d226225556858a636931eeabc (patch) | |
tree | e00cea674f3d6cc8c5584aa5b75239f11f6d229d /arch/arm/mach-ixp4xx | |
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/mach-ixp4xx')
-rw-r--r-- | arch/arm/mach-ixp4xx/common.c | 16 |
1 files changed, 3 insertions, 13 deletions
diff --git a/arch/arm/mach-ixp4xx/common.c b/arch/arm/mach-ixp4xx/common.c index b86a0055ab96..c1b12f945fc9 100644 --- a/arch/arm/mach-ixp4xx/common.c +++ b/arch/arm/mach-ixp4xx/common.c | |||
@@ -17,7 +17,6 @@ | |||
17 | #include <linux/mm.h> | 17 | #include <linux/mm.h> |
18 | #include <linux/init.h> | 18 | #include <linux/init.h> |
19 | #include <linux/serial.h> | 19 | #include <linux/serial.h> |
20 | #include <linux/sched.h> | ||
21 | #include <linux/tty.h> | 20 | #include <linux/tty.h> |
22 | #include <linux/platform_device.h> | 21 | #include <linux/platform_device.h> |
23 | #include <linux/serial_core.h> | 22 | #include <linux/serial_core.h> |
@@ -403,18 +402,9 @@ void __init ixp4xx_sys_init(void) | |||
403 | /* | 402 | /* |
404 | * sched_clock() | 403 | * sched_clock() |
405 | */ | 404 | */ |
406 | static DEFINE_CLOCK_DATA(cd); | 405 | static u32 notrace ixp4xx_read_sched_clock(void) |
407 | |||
408 | unsigned long long notrace sched_clock(void) | ||
409 | { | 406 | { |
410 | u32 cyc = *IXP4XX_OSTS; | 407 | return *IXP4XX_OSTS; |
411 | return cyc_to_sched_clock(&cd, cyc, (u32)~0); | ||
412 | } | ||
413 | |||
414 | static void notrace ixp4xx_update_sched_clock(void) | ||
415 | { | ||
416 | u32 cyc = *IXP4XX_OSTS; | ||
417 | update_sched_clock(&cd, cyc, (u32)~0); | ||
418 | } | 408 | } |
419 | 409 | ||
420 | /* | 410 | /* |
@@ -430,7 +420,7 @@ unsigned long ixp4xx_timer_freq = IXP4XX_TIMER_FREQ; | |||
430 | EXPORT_SYMBOL(ixp4xx_timer_freq); | 420 | EXPORT_SYMBOL(ixp4xx_timer_freq); |
431 | static void __init ixp4xx_clocksource_init(void) | 421 | static void __init ixp4xx_clocksource_init(void) |
432 | { | 422 | { |
433 | init_sched_clock(&cd, ixp4xx_update_sched_clock, 32, ixp4xx_timer_freq); | 423 | setup_sched_clock(ixp4xx_read_sched_clock, 32, ixp4xx_timer_freq); |
434 | 424 | ||
435 | clocksource_mmio_init(NULL, "OSTS", ixp4xx_timer_freq, 200, 32, | 425 | clocksource_mmio_init(NULL, "OSTS", ixp4xx_timer_freq, 200, 32, |
436 | ixp4xx_clocksource_read); | 426 | ixp4xx_clocksource_read); |