blob: b112406f19961932f1505aeafa09d402a2ca45b1 [file] [log] [blame]
Andi Kleen312df5f2005-05-16 21:53:28 -07001/* Ported over from i386 by AK, original copyright was:
2 *
3 * (C) Dominik Brodowski <linux@brodo.de> 2003
4 *
5 * Driver to use the Power Management Timer (PMTMR) available in some
6 * southbridges as primary timing source for the Linux kernel.
7 *
8 * Based on parts of linux/drivers/acpi/hardware/hwtimer.c, timer_pit.c,
9 * timer_hpet.c, and on Arjan van de Ven's implementation for 2.4.
10 *
11 * This file is licensed under the GPL v2.
12 *
13 * Dropped all the hardware bug workarounds for now. Hopefully they
14 * are not needed on 64bit chipsets.
15 */
16
17#include <linux/jiffies.h>
18#include <linux/kernel.h>
19#include <linux/time.h>
20#include <linux/init.h>
21#include <linux/cpumask.h>
Thomas Gleixner70a20022008-01-30 13:30:18 +010022#include <linux/acpi_pmtmr.h>
23
Andi Kleen312df5f2005-05-16 21:53:28 -070024#include <asm/io.h>
25#include <asm/proto.h>
26#include <asm/msr.h>
27#include <asm/vsyscall.h>
28
Andi Kleen312df5f2005-05-16 21:53:28 -070029static inline u32 cyc2us(u32 cycles)
30{
31 /* The Power Management Timer ticks at 3.579545 ticks per microsecond.
32 * 1 / PM_TIMER_FREQUENCY == 0.27936511 =~ 286/1024 [error: 0.024%]
33 *
34 * Even with HZ = 100, delta is at maximum 35796 ticks, so it can
35 * easily be multiplied with 286 (=0x11E) without having to fear
36 * u32 overflows.
37 */
38 cycles *= 286;
39 return (cycles >> 10);
40}
41
Andi Kleen0c3749c2006-02-03 21:51:41 +010042static unsigned pmtimer_wait_tick(void)
43{
44 u32 a, b;
45 for (a = b = inl(pmtmr_ioport) & ACPI_PM_MASK;
46 a == b;
47 b = inl(pmtmr_ioport) & ACPI_PM_MASK)
Andi Kleenc36cd162006-03-25 16:32:04 +010048 cpu_relax();
Andi Kleen0c3749c2006-02-03 21:51:41 +010049 return b;
50}
51
52/* note: wait time is rounded up to one tick */
53void pmtimer_wait(unsigned us)
54{
55 u32 a, b;
56 a = pmtimer_wait_tick();
57 do {
58 b = inl(pmtmr_ioport);
Andi Kleenc36cd162006-03-25 16:32:04 +010059 cpu_relax();
Andi Kleen0c3749c2006-02-03 21:51:41 +010060 } while (cyc2us(b - a) < us);
61}
62
Andi Kleen312df5f2005-05-16 21:53:28 -070063static int __init nopmtimer_setup(char *s)
64{
65 pmtmr_ioport = 0;
OGAWA Hirofumi9b410462006-03-31 02:30:33 -080066 return 1;
Andi Kleen312df5f2005-05-16 21:53:28 -070067}
68
69__setup("nopmtimer", nopmtimer_setup);