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omap: fix clocksource_32k to start from zero

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When the 32k sync timer is used for sched_clock(), it should count
time from the kernel boot (clocksource init) instead of the last HW
reset. Otherwise printk.time values will jump suddenly during the boot:

	[    0.000000] calling  omap2_clk_arch_init+0x0/0x138 @ 1
	[    0.000000] initcall omap2_clk_arch_init+0x0/0x138 returned -22 after 0 usecs
	[    0.000000] initcall omap2_clk_arch_init+0x0/0x138 returned with error code -22
	[    0.000000] calling  omap_init_clocksource_32k+0x0/0x98 @ 1
	[  508.697937] initcall omap_init_clocksource_32k+0x0/0x98 returned 0 after 0 usecs
	[  508.697967] calling  omap_init_devices+0x0/0x38 @ 1
	[  508.698425] initcall omap_init_devices+0x0/0x38 returned 0 after 0 usecs

This will confuse tools such as scripts/bootgraph.pl.

Signed-off-by: Aaro Koskinen <aaro.koskinen@nokia.com>
Acked-by: Kevin Hilman <khilman@deeprootsystems.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>
This commit is contained in:
Aaro Koskinen 2010-04-07 09:57:22 +00:00 committed by Tony Lindgren
parent e2bca7c76a
commit 2decb12e3e
1 changed files with 14 additions and 5 deletions
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19
arch/arm/plat-omap/common.c
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@ -100,10 +100,17 @@ EXPORT_SYMBOL(omap_get_var_config);
#include <linux/clocksource.h>
/*
* offset_32k holds the init time counter value. It is then subtracted
* from every counter read to achieve a counter that counts time from the
* kernel boot (needed for sched_clock()).
*/
static u32 offset_32k __read_mostly;
#ifdef CONFIG_ARCH_OMAP16XX
static cycle_t omap16xx_32k_read(struct clocksource *cs)
{
return omap_readl(OMAP16XX_TIMER_32K_SYNCHRONIZED);
return omap_readl(OMAP16XX_TIMER_32K_SYNCHRONIZED) - offset_32k;
}
#else
#define omap16xx_32k_read NULL
@ -112,7 +119,7 @@ static cycle_t omap16xx_32k_read(struct clocksource *cs)
#ifdef CONFIG_ARCH_OMAP2420
static cycle_t omap2420_32k_read(struct clocksource *cs)
{
return omap_readl(OMAP2420_32KSYNCT_BASE + 0x10);
return omap_readl(OMAP2420_32KSYNCT_BASE + 0x10) - offset_32k;
}
#else
#define omap2420_32k_read NULL
@ -121,7 +128,7 @@ static cycle_t omap2420_32k_read(struct clocksource *cs)
#ifdef CONFIG_ARCH_OMAP2430
static cycle_t omap2430_32k_read(struct clocksource *cs)
{
return omap_readl(OMAP2430_32KSYNCT_BASE + 0x10);
return omap_readl(OMAP2430_32KSYNCT_BASE + 0x10) - offset_32k;
}
#else
#define omap2430_32k_read NULL
@ -130,7 +137,7 @@ static cycle_t omap2430_32k_read(struct clocksource *cs)
#ifdef CONFIG_ARCH_OMAP3
static cycle_t omap34xx_32k_read(struct clocksource *cs)
{
return omap_readl(OMAP3430_32KSYNCT_BASE + 0x10);
return omap_readl(OMAP3430_32KSYNCT_BASE + 0x10) - offset_32k;
}
#else
#define omap34xx_32k_read NULL
@ -139,7 +146,7 @@ static cycle_t omap34xx_32k_read(struct clocksource *cs)
#ifdef CONFIG_ARCH_OMAP4
static cycle_t omap44xx_32k_read(struct clocksource *cs)
{
return omap_readl(OMAP4430_32KSYNCT_BASE + 0x10);
return omap_readl(OMAP4430_32KSYNCT_BASE + 0x10) - offset_32k;
}
#else
#define omap44xx_32k_read NULL
@ -227,6 +234,8 @@ static int __init omap_init_clocksource_32k(void)
clocksource_32k.mult = clocksource_hz2mult(32768,
clocksource_32k.shift);
offset_32k = clocksource_32k.read(&clocksource_32k);
if (clocksource_register(&clocksource_32k))
printk(err, clocksource_32k.name);
}