Commit 2decb12e authored by Aaro Koskinen's avatar Aaro Koskinen Committed by Tony Lindgren
Browse files

omap: fix clocksource_32k to start from zero 



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: default avatarAaro Koskinen <aaro.koskinen@nokia.com>
Acked-by: default avatarKevin Hilman <khilman@deeprootsystems.com>
Signed-off-by: default avatarTony Lindgren <tony@atomide.com>
parent e2bca7c7

arch/arm/plat-omap/common.c

+14 −5
Original line number Diff line number Diff line
@@ -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);

	}

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