android_kernel_xiaomi_sm8350/arch/x86_64/kernel/pmtimer.c
john stultz 1489939f0a [PATCH] time: x86_64: convert x86_64 to use GENERIC_TIME
This patch converts x86_64 to use the GENERIC_TIME infrastructure and adds
clocksource structures for both TSC and HPET (ACPI PM is shared w/ i386).

[akpm@osdl.org: fix printk timestamps]
[akpm@osdl.org: fix printk ckeanups]
[akpm@osdl.org: hpet build fix]
Signed-off-by: John Stultz <johnstul@us.ibm.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Andi Kleen <ak@muc.de>
Cc: Roman Zippel <zippel@linux-m68k.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-02-16 08:14:00 -08:00

70 lines
1.7 KiB
C

/* Ported over from i386 by AK, original copyright was:
*
* (C) Dominik Brodowski <linux@brodo.de> 2003
*
* Driver to use the Power Management Timer (PMTMR) available in some
* southbridges as primary timing source for the Linux kernel.
*
* Based on parts of linux/drivers/acpi/hardware/hwtimer.c, timer_pit.c,
* timer_hpet.c, and on Arjan van de Ven's implementation for 2.4.
*
* This file is licensed under the GPL v2.
*
* Dropped all the hardware bug workarounds for now. Hopefully they
* are not needed on 64bit chipsets.
*/
#include <linux/jiffies.h>
#include <linux/kernel.h>
#include <linux/time.h>
#include <linux/init.h>
#include <linux/cpumask.h>
#include <asm/io.h>
#include <asm/proto.h>
#include <asm/msr.h>
#include <asm/vsyscall.h>
#define ACPI_PM_MASK 0xFFFFFF /* limit it to 24 bits */
static inline u32 cyc2us(u32 cycles)
{
/* The Power Management Timer ticks at 3.579545 ticks per microsecond.
* 1 / PM_TIMER_FREQUENCY == 0.27936511 =~ 286/1024 [error: 0.024%]
*
* Even with HZ = 100, delta is at maximum 35796 ticks, so it can
* easily be multiplied with 286 (=0x11E) without having to fear
* u32 overflows.
*/
cycles *= 286;
return (cycles >> 10);
}
static unsigned pmtimer_wait_tick(void)
{
u32 a, b;
for (a = b = inl(pmtmr_ioport) & ACPI_PM_MASK;
a == b;
b = inl(pmtmr_ioport) & ACPI_PM_MASK)
cpu_relax();
return b;
}
/* note: wait time is rounded up to one tick */
void pmtimer_wait(unsigned us)
{
u32 a, b;
a = pmtimer_wait_tick();
do {
b = inl(pmtmr_ioport);
cpu_relax();
} while (cyc2us(b - a) < us);
}
static int __init nopmtimer_setup(char *s)
{
pmtmr_ioport = 0;
return 1;
}
__setup("nopmtimer", nopmtimer_setup);