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>
diff --git a/arch/arm/plat-omap/counter_32k.c b/arch/arm/plat-omap/counter_32k.c
index a6cbb71..5f0f229 100644
--- a/arch/arm/plat-omap/counter_32k.c
+++ b/arch/arm/plat-omap/counter_32k.c
@@ -17,7 +17,6 @@
#include <linux/clk.h>
#include <linux/err.h>
#include <linux/io.h>
-#include <linux/sched.h>
#include <linux/clocksource.h>
#include <asm/sched_clock.h>
@@ -37,41 +36,9 @@
#define OMAP16XX_TIMER_32K_SYNCHRONIZED 0xfffbc410
-/*
- * Returns current time from boot in nsecs. It's OK for this to wrap
- * around for now, as it's just a relative time stamp.
- */
-static DEFINE_CLOCK_DATA(cd);
-
-/*
- * Constants generated by clocks_calc_mult_shift(m, s, 32768, NSEC_PER_SEC, 60).
- * This gives a resolution of about 30us and a wrap period of about 36hrs.
- */
-#define SC_MULT 4000000000u
-#define SC_SHIFT 17
-
-static inline unsigned long long notrace _omap_32k_sched_clock(void)
+static u32 notrace omap_32k_read_sched_clock(void)
{
- u32 cyc = timer_32k_base ? __raw_readl(timer_32k_base) : 0;
- return cyc_to_fixed_sched_clock(&cd, cyc, (u32)~0, SC_MULT, SC_SHIFT);
-}
-
-#if defined(CONFIG_OMAP_32K_TIMER) && !defined(CONFIG_OMAP_MPU_TIMER)
-unsigned long long notrace sched_clock(void)
-{
- return _omap_32k_sched_clock();
-}
-#else
-unsigned long long notrace omap_32k_sched_clock(void)
-{
- return _omap_32k_sched_clock();
-}
-#endif
-
-static void notrace omap_update_sched_clock(void)
-{
- u32 cyc = timer_32k_base ? __raw_readl(timer_32k_base) : 0;
- update_sched_clock(&cd, cyc, (u32)~0);
+ return timer_32k_base ? __raw_readl(timer_32k_base) : 0;
}
/**
@@ -147,8 +114,7 @@
clocksource_mmio_readl_up))
printk(err, "32k_counter");
- init_fixed_sched_clock(&cd, omap_update_sched_clock, 32,
- 32768, SC_MULT, SC_SHIFT);
+ setup_sched_clock(omap_32k_read_sched_clock, 32, 32768);
}
return 0;
}