| /* 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> |
| |
| /* The I/O port the PMTMR resides at. |
| * The location is detected during setup_arch(), |
| * in arch/i386/kernel/acpi/boot.c */ |
| u32 pmtmr_ioport; |
| |
| /* value of the Power timer at last timer interrupt */ |
| static u32 offset_delay; |
| static u32 last_pmtmr_tick; |
| |
| #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); |
| } |
| |
| int pmtimer_mark_offset(void) |
| { |
| static int first_run = 1; |
| unsigned long tsc; |
| u32 lost; |
| |
| u32 tick = inl(pmtmr_ioport); |
| u32 delta; |
| |
| delta = cyc2us((tick - last_pmtmr_tick) & ACPI_PM_MASK); |
| |
| last_pmtmr_tick = tick; |
| monotonic_base += delta * NSEC_PER_USEC; |
| |
| delta += offset_delay; |
| |
| lost = delta / (USEC_PER_SEC / HZ); |
| offset_delay = delta % (USEC_PER_SEC / HZ); |
| |
| rdtscll(tsc); |
| vxtime.last_tsc = tsc - offset_delay * cpu_khz; |
| |
| /* don't calculate delay for first run, |
| or if we've got less then a tick */ |
| if (first_run || (lost < 1)) { |
| first_run = 0; |
| offset_delay = 0; |
| } |
| |
| return lost - 1; |
| } |
| |
| unsigned int do_gettimeoffset_pm(void) |
| { |
| u32 now, offset, delta = 0; |
| |
| offset = last_pmtmr_tick; |
| now = inl(pmtmr_ioport); |
| delta = (now - offset) & ACPI_PM_MASK; |
| |
| return offset_delay + cyc2us(delta); |
| } |
| |
| |
| static int __init nopmtimer_setup(char *s) |
| { |
| pmtmr_ioport = 0; |
| return 0; |
| } |
| |
| __setup("nopmtimer", nopmtimer_setup); |