projects / deliverable / linux.git / blame
| Commit | Line | Data |
|---|---|---|
| 312df5f1 AK |
1 | /* 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> | |
| 70a20025 TG |
22 | #include <linux/acpi_pmtmr.h> |
| 23 | ||
| 312df5f1 AK |
24 | #include <asm/io.h> |
| 25 | #include <asm/proto.h> | |
| 26 | #include <asm/msr.h> | |
| 27 | #include <asm/vsyscall.h> | |
| 28 | ||
| 312df5f1 AK |
29 | static 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 | ||
| 0c3749c4 AK |
42 | static 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) | |
| c36cd16f | 48 | cpu_relax(); |
| 0c3749c4 AK |
49 | return b; |
| 50 | } | |
| 51 | ||
| 52 | /* note: wait time is rounded up to one tick */ | |
| 53 | void pmtimer_wait(unsigned us) | |
| 54 | { | |
| 55 | u32 a, b; | |
| 56 | a = pmtimer_wait_tick(); | |
| 57 | do { | |
| 58 | b = inl(pmtmr_ioport); | |
| c36cd16f | 59 | cpu_relax(); |
| 0c3749c4 AK |
60 | } while (cyc2us(b - a) < us); |
| 61 | } | |
| 62 | ||
| 312df5f1 AK |
63 | static int __init nopmtimer_setup(char *s) |
| 64 | { | |
| 65 | pmtmr_ioport = 0; | |
| 9b41046c | 66 | return 1; |
| 312df5f1 AK |
67 | } |
| 68 | ||
| 69 | __setup("nopmtimer", nopmtimer_setup); |