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提交 61743fe4 编写于 作者: J john stultz 提交者： Linus Torvalds
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[PATCH] Time: i386 Conversion - part 4: Remove Old timer_opts Code 

Remove the old timers/timer_opts infrastructure which has been disabled.  It
is a fairly straightforward set of deletions

Note that this does not provide any i386 clocksources, so you will only have
the jiffies clocksource.  To get full replacements for the code being removed
here, the timeofday-clocks-i386 patch will be needed.
Signed-off-by: NJohn Stultz <johnstul@us.ibm.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
上级 6f84fa2f
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arch/i386/kernel/timers/Makefile 已删除 100644 → 0
浏览文件 @ 6f84fa2f
#
# Makefile for x86 timers
#
obj-y := timer.o timer_none.o timer_tsc.o timer_pit.o common.o
obj-$(CONFIG_X86_CYCLONE_TIMER) += timer_cyclone.o
obj-$(CONFIG_HPET_TIMER) += timer_hpet.o
obj-$(CONFIG_X86_PM_TIMER) += timer_pm.o
arch/i386/kernel/timers/common.c 已删除 100644 → 0
浏览文件 @ 6f84fa2f
/*
* Common functions used across the timers go here
*/
#include <linux/init.h>
#include <linux/timex.h>
#include <linux/errno.h>
#include <linux/jiffies.h>
#include <linux/module.h>
#include <asm/io.h>
#include <asm/timer.h>
#include <asm/hpet.h>
#include "mach_timer.h"
/* ------ Calibrate the TSC -------
* Return 2^32 * (1 / (TSC clocks per usec)) for do_fast_gettimeoffset().
* Too much 64-bit arithmetic here to do this cleanly in C, and for
* accuracy's sake we want to keep the overhead on the CTC speaker (channel 2)
* output busy loop as low as possible. We avoid reading the CTC registers
* directly because of the awkward 8-bit access mechanism of the 82C54
* device.
*/
#define CALIBRATE_TIME (5 * 1000020/HZ)
unsigned long calibrate_tsc(void)
{
mach_prepare_counter();
{
unsigned long startlow, starthigh;
unsigned long endlow, endhigh;
unsigned long count;
rdtsc(startlow,starthigh);
mach_countup(&count);
rdtsc(endlow,endhigh);
/* Error: ECTCNEVERSET */
if (count <= 1)
goto bad_ctc;
/* 64-bit subtract - gcc just messes up with long longs */
__asm__("subl %2,%0\n\t"
"sbbl %3,%1"
:"=a" (endlow), "=d" (endhigh)
:"g" (startlow), "g" (starthigh),
"0" (endlow), "1" (endhigh));
/* Error: ECPUTOOFAST */
if (endhigh)
goto bad_ctc;
/* Error: ECPUTOOSLOW */
if (endlow <= CALIBRATE_TIME)
goto bad_ctc;
__asm__("divl %2"
:"=a" (endlow), "=d" (endhigh)
:"r" (endlow), "0" (0), "1" (CALIBRATE_TIME));
return endlow;
}
/*
* The CTC wasn't reliable: we got a hit on the very first read,
* or the CPU was so fast/slow that the quotient wouldn't fit in
* 32 bits..
*/
bad_ctc:
return 0;
}
#ifdef CONFIG_HPET_TIMER
/* ------ Calibrate the TSC using HPET -------
* Return 2^32 * (1 / (TSC clocks per usec)) for getting the CPU freq.
* Second output is parameter 1 (when non NULL)
* Set 2^32 * (1 / (tsc per HPET clk)) for delay_hpet().
* calibrate_tsc() calibrates the processor TSC by comparing
* it to the HPET timer of known frequency.
* Too much 64-bit arithmetic here to do this cleanly in C
*/
#define CALIBRATE_CNT_HPET (5 * hpet_tick)
#define CALIBRATE_TIME_HPET (5 * KERNEL_TICK_USEC)
unsigned long __devinit calibrate_tsc_hpet(unsigned long *tsc_hpet_quotient_ptr)
{
unsigned long tsc_startlow, tsc_starthigh;
unsigned long tsc_endlow, tsc_endhigh;
unsigned long hpet_start, hpet_end;
unsigned long result, remain;
hpet_start = hpet_readl(HPET_COUNTER);
rdtsc(tsc_startlow, tsc_starthigh);
do {
hpet_end = hpet_readl(HPET_COUNTER);
} while ((hpet_end - hpet_start) < CALIBRATE_CNT_HPET);
rdtsc(tsc_endlow, tsc_endhigh);
/* 64-bit subtract - gcc just messes up with long longs */
__asm__("subl %2,%0\n\t"
"sbbl %3,%1"
:"=a" (tsc_endlow), "=d" (tsc_endhigh)
:"g" (tsc_startlow), "g" (tsc_starthigh),
"0" (tsc_endlow), "1" (tsc_endhigh));
/* Error: ECPUTOOFAST */
if (tsc_endhigh)
goto bad_calibration;
/* Error: ECPUTOOSLOW */
if (tsc_endlow <= CALIBRATE_TIME_HPET)
goto bad_calibration;
ASM_DIV64_REG(result, remain, tsc_endlow, 0, CALIBRATE_TIME_HPET);
if (remain > (tsc_endlow >> 1))
result++; /* rounding the result */
if (tsc_hpet_quotient_ptr) {
unsigned long tsc_hpet_quotient;
ASM_DIV64_REG(tsc_hpet_quotient, remain, tsc_endlow, 0,
CALIBRATE_CNT_HPET);
if (remain > (tsc_endlow >> 1))
tsc_hpet_quotient++; /* rounding the result */
*tsc_hpet_quotient_ptr = tsc_hpet_quotient;
}
return result;
bad_calibration:
/*
* the CPU was so fast/slow that the quotient wouldn't fit in
* 32 bits..
*/
return 0;
}
#endif
unsigned long read_timer_tsc(void)
{
unsigned long retval;
rdtscl(retval);
return retval;
}
/* calculate cpu_khz */
void init_cpu_khz(void)
{
if (cpu_has_tsc) {
unsigned long tsc_quotient = calibrate_tsc();
if (tsc_quotient) {
/* report CPU clock rate in Hz.
* The formula is (10^6 * 2^32) / (2^32 * 1 / (clocks/us)) =
* clock/second. Our precision is about 100 ppm.
*/
{ unsigned long eax=0, edx=1000;
__asm__("divl %2"
:"=a" (cpu_khz), "=d" (edx)
:"r" (tsc_quotient),
"0" (eax), "1" (edx));
printk("Detected %u.%03u MHz processor.\n",
cpu_khz / 1000, cpu_khz % 1000);
}
}
}
}
arch/i386/kernel/timers/timer.c 已删除 100644 → 0
浏览文件 @ 6f84fa2f
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/string.h>
#include <asm/timer.h>
#ifdef CONFIG_HPET_TIMER
/*
* HPET memory read is slower than tsc reads, but is more dependable as it
* always runs at constant frequency and reduces complexity due to
* cpufreq. So, we prefer HPET timer to tsc based one. Also, we cannot use
* timer_pit when HPET is active. So, we default to timer_tsc.
*/
#endif
/* list of timers, ordered by preference, NULL terminated */
static struct init_timer_opts* __initdata timers[] = {
#ifdef CONFIG_X86_CYCLONE_TIMER
&timer_cyclone_init,
#endif
#ifdef CONFIG_HPET_TIMER
&timer_hpet_init,
#endif
#ifdef CONFIG_X86_PM_TIMER
&timer_pmtmr_init,
#endif
&timer_tsc_init,
&timer_pit_init,
NULL,
};
static char clock_override[10] __initdata;
static int __init clock_setup(char* str)
{
if (str)
strlcpy(clock_override, str, sizeof(clock_override));
return 1;
}
__setup("clock=", clock_setup);
/* The chosen timesource has been found to be bad.
* Fall back to a known good timesource (the PIT)
*/
void clock_fallback(void)
{
cur_timer = &timer_pit;
}
/* iterates through the list of timers, returning the first
* one that initializes successfully.
*/
struct timer_opts* __init select_timer(void)
{
int i = 0;
/* find most preferred working timer */
while (timers[i]) {
if (timers[i]->init)
if (timers[i]->init(clock_override) == 0)
return timers[i]->opts;
++i;
}
panic("select_timer: Cannot find a suitable timer\n");
return NULL;
}
int read_current_timer(unsigned long *timer_val)
{
if (cur_timer->read_timer) {
*timer_val = cur_timer->read_timer();
return 0;
}
return -1;
}
arch/i386/kernel/timers/timer_cyclone.c 已删除 100644 → 0
浏览文件 @ 6f84fa2f
/* Cyclone-timer:
* This code implements timer_ops for the cyclone counter found
* on IBM x440, x360, and other Summit based systems.
*
* Copyright (C) 2002 IBM, John Stultz (johnstul@us.ibm.com)
*/
#include <linux/spinlock.h>
#include <linux/init.h>
#include <linux/timex.h>
#include <linux/errno.h>
#include <linux/string.h>
#include <linux/jiffies.h>
#include <asm/timer.h>
#include <asm/io.h>
#include <asm/pgtable.h>
#include <asm/fixmap.h>
#include <asm/i8253.h>
#include "io_ports.h"
/* Number of usecs that the last interrupt was delayed */
static int delay_at_last_interrupt;
#define CYCLONE_CBAR_ADDR 0xFEB00CD0
#define CYCLONE_PMCC_OFFSET 0x51A0
#define CYCLONE_MPMC_OFFSET 0x51D0
#define CYCLONE_MPCS_OFFSET 0x51A8
#define CYCLONE_TIMER_FREQ 100000000
#define CYCLONE_TIMER_MASK (((u64)1<<40)-1) /* 40 bit mask */
int use_cyclone = 0;
static u32* volatile cyclone_timer; /* Cyclone MPMC0 register */
static u32 last_cyclone_low;
static u32 last_cyclone_high;
static unsigned long long monotonic_base;
static seqlock_t monotonic_lock = SEQLOCK_UNLOCKED;
/* helper macro to atomically read both cyclone counter registers */
#define read_cyclone_counter(low,high) \
do{ \
high = cyclone_timer[1]; low = cyclone_timer[0]; \
} while (high != cyclone_timer[1]);
static void mark_offset_cyclone(void)
{
unsigned long lost, delay;
unsigned long delta = last_cyclone_low;
int count;
unsigned long long this_offset, last_offset;
write_seqlock(&monotonic_lock);
last_offset = ((unsigned long long)last_cyclone_high<<32)|last_cyclone_low;
spin_lock(&i8253_lock);
read_cyclone_counter(last_cyclone_low,last_cyclone_high);
/* read values for delay_at_last_interrupt */
outb_p(0x00, 0x43); /* latch the count ASAP */
count = inb_p(0x40); /* read the latched count */
count |= inb(0x40) << 8;
/*
* VIA686a test code... reset the latch if count > max + 1
* from timer_pit.c - cjb
*/
if (count > LATCH) {
outb_p(0x34, PIT_MODE);
outb_p(LATCH & 0xff, PIT_CH0);
outb(LATCH >> 8, PIT_CH0);
count = LATCH - 1;
}
spin_unlock(&i8253_lock);
/* lost tick compensation */
delta = last_cyclone_low - delta;
delta /= (CYCLONE_TIMER_FREQ/1000000);
delta += delay_at_last_interrupt;
lost = delta/(1000000/HZ);
delay = delta%(1000000/HZ);
if (lost >= 2)
jiffies_64 += lost-1;
/* update the monotonic base value */
this_offset = ((unsigned long long)last_cyclone_high<<32)|last_cyclone_low;
monotonic_base += (this_offset - last_offset) & CYCLONE_TIMER_MASK;
write_sequnlock(&monotonic_lock);
/* calculate delay_at_last_interrupt */
count = ((LATCH-1) - count) * TICK_SIZE;
delay_at_last_interrupt = (count + LATCH/2) / LATCH;
/* catch corner case where tick rollover occured
* between cyclone and pit reads (as noted when
* usec delta is > 90% # of usecs/tick)
*/
if (lost && abs(delay - delay_at_last_interrupt) > (900000/HZ))
jiffies_64++;
}
static unsigned long get_offset_cyclone(void)
{
u32 offset;
if(!cyclone_timer)
return delay_at_last_interrupt;
/* Read the cyclone timer */
offset = cyclone_timer[0];
/* .. relative to previous jiffy */
offset = offset - last_cyclone_low;
/* convert cyclone ticks to microseconds */
/* XXX slow, can we speed this up? */
offset = offset/(CYCLONE_TIMER_FREQ/1000000);
/* our adjusted time offset in microseconds */
return delay_at_last_interrupt + offset;
}
static unsigned long long monotonic_clock_cyclone(void)
{
u32 now_low, now_high;
unsigned long long last_offset, this_offset, base;
unsigned long long ret;
unsigned seq;
/* atomically read monotonic base & last_offset */
do {
seq = read_seqbegin(&monotonic_lock);
last_offset = ((unsigned long long)last_cyclone_high<<32)|last_cyclone_low;
base = monotonic_base;
} while (read_seqretry(&monotonic_lock, seq));
/* Read the cyclone counter */
read_cyclone_counter(now_low,now_high);
this_offset = ((unsigned long long)now_high<<32)|now_low;
/* convert to nanoseconds */
ret = base + ((this_offset - last_offset)&CYCLONE_TIMER_MASK);
return ret * (1000000000 / CYCLONE_TIMER_FREQ);
}
static int __init init_cyclone(char* override)
{
u32* reg;
u32 base; /* saved cyclone base address */
u32 pageaddr; /* page that contains cyclone_timer register */
u32 offset; /* offset from pageaddr to cyclone_timer register */
int i;
/* check clock override */
if (override[0] && strncmp(override,"cyclone",7))
return -ENODEV;
/*make sure we're on a summit box*/
if(!use_cyclone) return -ENODEV;
printk(KERN_INFO "Summit chipset: Starting Cyclone Counter.\n");
/* find base address */
pageaddr = (CYCLONE_CBAR_ADDR)&PAGE_MASK;
offset = (CYCLONE_CBAR_ADDR)&(~PAGE_MASK);
set_fixmap_nocache(FIX_CYCLONE_TIMER, pageaddr);
reg = (u32*)(fix_to_virt(FIX_CYCLONE_TIMER) + offset);
if(!reg){
printk(KERN_ERR "Summit chipset: Could not find valid CBAR register.\n");
return -ENODEV;
}
base = *reg;
if(!base){
printk(KERN_ERR "Summit chipset: Could not find valid CBAR value.\n");
return -ENODEV;
}
/* setup PMCC */
pageaddr = (base + CYCLONE_PMCC_OFFSET)&PAGE_MASK;
offset = (base + CYCLONE_PMCC_OFFSET)&(~PAGE_MASK);
set_fixmap_nocache(FIX_CYCLONE_TIMER, pageaddr);
reg = (u32*)(fix_to_virt(FIX_CYCLONE_TIMER) + offset);
if(!reg){
printk(KERN_ERR "Summit chipset: Could not find valid PMCC register.\n");
return -ENODEV;
}
reg[0] = 0x00000001;
/* setup MPCS */
pageaddr = (base + CYCLONE_MPCS_OFFSET)&PAGE_MASK;
offset = (base + CYCLONE_MPCS_OFFSET)&(~PAGE_MASK);
set_fixmap_nocache(FIX_CYCLONE_TIMER, pageaddr);
reg = (u32*)(fix_to_virt(FIX_CYCLONE_TIMER) + offset);
if(!reg){
printk(KERN_ERR "Summit chipset: Could not find valid MPCS register.\n");
return -ENODEV;
}
reg[0] = 0x00000001;
/* map in cyclone_timer */
pageaddr = (base + CYCLONE_MPMC_OFFSET)&PAGE_MASK;
offset = (base + CYCLONE_MPMC_OFFSET)&(~PAGE_MASK);
set_fixmap_nocache(FIX_CYCLONE_TIMER, pageaddr);
cyclone_timer = (u32*)(fix_to_virt(FIX_CYCLONE_TIMER) + offset);
if(!cyclone_timer){
printk(KERN_ERR "Summit chipset: Could not find valid MPMC register.\n");
return -ENODEV;
}
/*quick test to make sure its ticking*/
for(i=0; i<3; i++){
u32 old = cyclone_timer[0];
int stall = 100;
while(stall--) barrier();
if(cyclone_timer[0] == old){
printk(KERN_ERR "Summit chipset: Counter not counting! DISABLED\n");
cyclone_timer = 0;
return -ENODEV;
}
}
init_cpu_khz();
/* Everything looks good! */
return 0;
}
static void delay_cyclone(unsigned long loops)
{
unsigned long bclock, now;
if(!cyclone_timer)
return;
bclock = cyclone_timer[0];
do {
rep_nop();
now = cyclone_timer[0];
} while ((now-bclock) < loops);
}
/************************************************************/
/* cyclone timer_opts struct */
static struct timer_opts timer_cyclone = {
.name = "cyclone",
.mark_offset = mark_offset_cyclone,
.get_offset = get_offset_cyclone,
.monotonic_clock = monotonic_clock_cyclone,
.delay = delay_cyclone,
};
struct init_timer_opts __initdata timer_cyclone_init = {
.init = init_cyclone,
.opts = &timer_cyclone,
};
arch/i386/kernel/timers/timer_hpet.c 已删除 100644 → 0
浏览文件 @ 6f84fa2f
/*
* This code largely moved from arch/i386/kernel/time.c.
* See comments there for proper credits.
*/
#include <linux/spinlock.h>
#include <linux/init.h>
#include <linux/timex.h>
#include <linux/errno.h>
#include <linux/string.h>
#include <linux/jiffies.h>
#include <asm/timer.h>
#include <asm/io.h>
#include <asm/processor.h>
#include "io_ports.h"
#include "mach_timer.h"
#include <asm/hpet.h>
static unsigned long hpet_usec_quotient __read_mostly; /* convert hpet clks to usec */
static unsigned long tsc_hpet_quotient __read_mostly; /* convert tsc to hpet clks */
static unsigned long hpet_last; /* hpet counter value at last tick*/
static unsigned long last_tsc_low; /* lsb 32 bits of Time Stamp Counter */
static unsigned long last_tsc_high; /* msb 32 bits of Time Stamp Counter */
static unsigned long long monotonic_base;
static seqlock_t monotonic_lock = SEQLOCK_UNLOCKED;
/* convert from cycles(64bits) => nanoseconds (64bits)
* basic equation:
* ns = cycles / (freq / ns_per_sec)
* ns = cycles * (ns_per_sec / freq)
* ns = cycles * (10^9 / (cpu_khz * 10^3))
* ns = cycles * (10^6 / cpu_khz)
*
* Then we use scaling math (suggested by george@mvista.com) to get:
* ns = cycles * (10^6 * SC / cpu_khz) / SC
* ns = cycles * cyc2ns_scale / SC
*
* And since SC is a constant power of two, we can convert the div
* into a shift.
*
* We can use khz divisor instead of mhz to keep a better percision, since
* cyc2ns_scale is limited to 10^6 * 2^10, which fits in 32 bits.
* (mathieu.desnoyers@polymtl.ca)
*
* -johnstul@us.ibm.com "math is hard, lets go shopping!"
*/
static unsigned long cyc2ns_scale __read_mostly;
#define CYC2NS_SCALE_FACTOR 10 /* 2^10, carefully chosen */
static inline void set_cyc2ns_scale(unsigned long cpu_khz)
{
cyc2ns_scale = (1000000 << CYC2NS_SCALE_FACTOR)/cpu_khz;
}
static inline unsigned long long cycles_2_ns(unsigned long long cyc)
{
return (cyc * cyc2ns_scale) >> CYC2NS_SCALE_FACTOR;
}
static unsigned long long monotonic_clock_hpet(void)
{
unsigned long long last_offset, this_offset, base;
unsigned seq;
/* atomically read monotonic base & last_offset */
do {
seq = read_seqbegin(&monotonic_lock);
last_offset = ((unsigned long long)last_tsc_high<<32)|last_tsc_low;
base = monotonic_base;
} while (read_seqretry(&monotonic_lock, seq));
/* Read the Time Stamp Counter */
rdtscll(this_offset);
/* return the value in ns */
return base + cycles_2_ns(this_offset - last_offset);
}
static unsigned long get_offset_hpet(void)
{
register unsigned long eax, edx;
eax = hpet_readl(HPET_COUNTER);
eax -= hpet_last; /* hpet delta */
eax = min(hpet_tick, eax);
/*
* Time offset = (hpet delta) * ( usecs per HPET clock )
* = (hpet delta) * ( usecs per tick / HPET clocks per tick)
* = (hpet delta) * ( hpet_usec_quotient ) / (2^32)
*
* Where,
* hpet_usec_quotient = (2^32 * usecs per tick)/HPET clocks per tick
*
* Using a mull instead of a divl saves some cycles in critical path.
*/
ASM_MUL64_REG(eax, edx, hpet_usec_quotient, eax);
/* our adjusted time offset in microseconds */
return edx;
}
static void mark_offset_hpet(void)
{
unsigned long long this_offset, last_offset;
unsigned long offset;
write_seqlock(&monotonic_lock);
last_offset = ((unsigned long long)last_tsc_high<<32)|last_tsc_low;
rdtsc(last_tsc_low, last_tsc_high);
if (hpet_use_timer)
offset = hpet_readl(HPET_T0_CMP) - hpet_tick;
else
offset = hpet_readl(HPET_COUNTER);
if (unlikely(((offset - hpet_last) >= (2*hpet_tick)) && (hpet_last != 0))) {
int lost_ticks = ((offset - hpet_last) / hpet_tick) - 1;
jiffies_64 += lost_ticks;
}
hpet_last = offset;
/* update the monotonic base value */
this_offset = ((unsigned long long)last_tsc_high<<32)|last_tsc_low;
monotonic_base += cycles_2_ns(this_offset - last_offset);
write_sequnlock(&monotonic_lock);
}
static void delay_hpet(unsigned long loops)
{
unsigned long hpet_start, hpet_end;
unsigned long eax;
/* loops is the number of cpu cycles. Convert it to hpet clocks */
ASM_MUL64_REG(eax, loops, tsc_hpet_quotient, loops);
hpet_start = hpet_readl(HPET_COUNTER);
do {
rep_nop();
hpet_end = hpet_readl(HPET_COUNTER);
} while ((hpet_end - hpet_start) < (loops));
}
static struct timer_opts timer_hpet;
static int __init init_hpet(char* override)
{
unsigned long result, remain;
/* check clock override */
if (override[0] && strncmp(override,"hpet",4))
return -ENODEV;
if (!is_hpet_enabled())
return -ENODEV;
printk("Using HPET for gettimeofday\n");
if (cpu_has_tsc) {
unsigned long tsc_quotient = calibrate_tsc_hpet(&tsc_hpet_quotient);
if (tsc_quotient) {
/* report CPU clock rate in Hz.
* The formula is (10^6 * 2^32) / (2^32 * 1 / (clocks/us)) =
* clock/second. Our precision is about 100 ppm.
*/
{ unsigned long eax=0, edx=1000;
ASM_DIV64_REG(cpu_khz, edx, tsc_quotient,
eax, edx);
printk("Detected %u.%03u MHz processor.\n",
cpu_khz / 1000, cpu_khz % 1000);
}
set_cyc2ns_scale(cpu_khz);
}
/* set this only when cpu_has_tsc */
timer_hpet.read_timer = read_timer_tsc;
}
/*
* Math to calculate hpet to usec multiplier
* Look for the comments at get_offset_hpet()
*/
ASM_DIV64_REG(result, remain, hpet_tick, 0, KERNEL_TICK_USEC);
if (remain > (hpet_tick >> 1))
result++; /* rounding the result */
hpet_usec_quotient = result;
return 0;
}
static int hpet_resume(void)
{
write_seqlock(&monotonic_lock);
/* Assume this is the last mark offset time */
rdtsc(last_tsc_low, last_tsc_high);
if (hpet_use_timer)
hpet_last = hpet_readl(HPET_T0_CMP) - hpet_tick;
else
hpet_last = hpet_readl(HPET_COUNTER);
write_sequnlock(&monotonic_lock);
return 0;
}
/************************************************************/
/* tsc timer_opts struct */
static struct timer_opts timer_hpet __read_mostly = {
.name = "hpet",
.mark_offset = mark_offset_hpet,
.get_offset = get_offset_hpet,
.monotonic_clock = monotonic_clock_hpet,
.delay = delay_hpet,
.resume = hpet_resume,
};
struct init_timer_opts __initdata timer_hpet_init = {
.init = init_hpet,
.opts = &timer_hpet,
};
arch/i386/kernel/timers/timer_none.c 已删除 100644 → 0
浏览文件 @ 6f84fa2f
#include <linux/init.h>
#include <asm/timer.h>
static void mark_offset_none(void)
{
/* nothing needed */
}
static unsigned long get_offset_none(void)
{
return 0;
}
static unsigned long long monotonic_clock_none(void)
{
return 0;
}
static void delay_none(unsigned long loops)
{
int d0;
__asm__ __volatile__(
"\tjmp 1f\n"
".align 16\n"
"1:\tjmp 2f\n"
".align 16\n"
"2:\tdecl %0\n\tjns 2b"
:"=&a" (d0)
:"0" (loops));
}
/* none timer_opts struct */
struct timer_opts timer_none = {
.name = "none",
.mark_offset = mark_offset_none,
.get_offset = get_offset_none,
.monotonic_clock = monotonic_clock_none,
.delay = delay_none,
};
arch/i386/kernel/timers/timer_pit.c 已删除 100644 → 0
浏览文件 @ 6f84fa2f
/*
* This code largely moved from arch/i386/kernel/time.c.
* See comments there for proper credits.
*/
#include <linux/spinlock.h>
#include <linux/module.h>
#include <linux/device.h>
#include <linux/sysdev.h>
#include <linux/timex.h>
#include <asm/delay.h>
#include <asm/mpspec.h>
#include <asm/timer.h>
#include <asm/smp.h>
#include <asm/io.h>
#include <asm/arch_hooks.h>
#include <asm/i8253.h>
#include "do_timer.h"
#include "io_ports.h"
static int count_p; /* counter in get_offset_pit() */
static int __init init_pit(char* override)
{
/* check clock override */
if (override[0] && strncmp(override,"pit",3))
printk(KERN_ERR "Warning: clock= override failed. Defaulting "
"to PIT\n");
init_cpu_khz();
count_p = LATCH;
return 0;
}
static void mark_offset_pit(void)
{
/* nothing needed */
}
static unsigned long long monotonic_clock_pit(void)
{
return 0;
}
static void delay_pit(unsigned long loops)
{
int d0;
__asm__ __volatile__(
"\tjmp 1f\n"
".align 16\n"
"1:\tjmp 2f\n"
".align 16\n"
"2:\tdecl %0\n\tjns 2b"
:"=&a" (d0)
:"0" (loops));
}
/* This function must be called with xtime_lock held.
* It was inspired by Steve McCanne's microtime-i386 for BSD. -- jrs
*
* However, the pc-audio speaker driver changes the divisor so that
* it gets interrupted rather more often - it loads 64 into the
* counter rather than 11932! This has an adverse impact on
* do_gettimeoffset() -- it stops working! What is also not
* good is that the interval that our timer function gets called
* is no longer 10.0002 ms, but 9.9767 ms. To get around this
* would require using a different timing source. Maybe someone
* could use the RTC - I know that this can interrupt at frequencies
* ranging from 8192Hz to 2Hz. If I had the energy, I'd somehow fix
* it so that at startup, the timer code in sched.c would select
* using either the RTC or the 8253 timer. The decision would be
* based on whether there was any other device around that needed
* to trample on the 8253. I'd set up the RTC to interrupt at 1024 Hz,
* and then do some jiggery to have a version of do_timer that
* advanced the clock by 1/1024 s. Every time that reached over 1/100
* of a second, then do all the old code. If the time was kept correct
* then do_gettimeoffset could just return 0 - there is no low order
* divider that can be accessed.
*
* Ideally, you would be able to use the RTC for the speaker driver,
* but it appears that the speaker driver really needs interrupt more
* often than every 120 us or so.
*
* Anyway, this needs more thought.... pjsg (1993-08-28)
*
* If you are really that interested, you should be reading
* comp.protocols.time.ntp!
*/
static unsigned long get_offset_pit(void)
{
int count;
unsigned long flags;
static unsigned long jiffies_p = 0;
/*
* cache volatile jiffies temporarily; we have xtime_lock.
*/
unsigned long jiffies_t;
spin_lock_irqsave(&i8253_lock, flags);
/* timer count may underflow right here */
outb_p(0x00, PIT_MODE); /* latch the count ASAP */
count = inb_p(PIT_CH0); /* read the latched count */
/*
* We do this guaranteed double memory access instead of a _p
* postfix in the previous port access. Wheee, hackady hack
*/
jiffies_t = jiffies;
count |= inb_p(PIT_CH0) << 8;
/* VIA686a test code... reset the latch if count > max + 1 */
if (count > LATCH) {
outb_p(0x34, PIT_MODE);
outb_p(LATCH & 0xff, PIT_CH0);
outb(LATCH >> 8, PIT_CH0);
count = LATCH - 1;
}
/*
* avoiding timer inconsistencies (they are rare, but they happen)...
* there are two kinds of problems that must be avoided here:
* 1. the timer counter underflows
* 2. hardware problem with the timer, not giving us continuous time,
* the counter does small "jumps" upwards on some Pentium systems,
* (see c't 95/10 page 335 for Neptun bug.)
*/
if( jiffies_t == jiffies_p ) {
if( count > count_p ) {
/* the nutcase */
count = do_timer_overflow(count);
}
} else
jiffies_p = jiffies_t;
count_p = count;
spin_unlock_irqrestore(&i8253_lock, flags);
count = ((LATCH-1) - count) * TICK_SIZE;
count = (count + LATCH/2) / LATCH;
return count;
}
/* tsc timer_opts struct */
struct timer_opts timer_pit = {
.name = "pit",
.mark_offset = mark_offset_pit,
.get_offset = get_offset_pit,
.monotonic_clock = monotonic_clock_pit,
.delay = delay_pit,
};
struct init_timer_opts __initdata timer_pit_init = {
.init = init_pit,
.opts = &timer_pit,
};
arch/i386/kernel/timers/timer_pm.c 已删除 100644 → 0
浏览文件 @ 6f84fa2f
/*
* (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.
*/
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/device.h>
#include <linux/init.h>
#include <linux/pci.h>
#include <asm/types.h>
#include <asm/timer.h>
#include <asm/smp.h>
#include <asm/io.h>
#include <asm/arch_hooks.h>
#include <linux/timex.h>
#include "mach_timer.h"
/* Number of PMTMR ticks expected during calibration run */
#define PMTMR_TICKS_PER_SEC 3579545
#define PMTMR_EXPECTED_RATE \
((CALIBRATE_LATCH * (PMTMR_TICKS_PER_SEC >> 10)) / (CLOCK_TICK_RATE>>10))
/* The I/O port the PMTMR resides at.
* The location is detected during setup_arch(),
* in arch/i386/acpi/boot.c */
u32 pmtmr_ioport = 0;
/* value of the Power timer at last timer interrupt */
static u32 offset_tick;
static u32 offset_delay;
static unsigned long long monotonic_base;
static seqlock_t monotonic_lock = SEQLOCK_UNLOCKED;
#define ACPI_PM_MASK 0xFFFFFF /* limit it to 24 bits */
static int pmtmr_need_workaround __read_mostly = 1;
/*helper function to safely read acpi pm timesource*/
static inline u32 read_pmtmr(void)
{
if (pmtmr_need_workaround) {
u32 v1, v2, v3;
/* It has been reported that because of various broken
* chipsets (ICH4, PIIX4 and PIIX4E) where the ACPI PM time
* source is not latched, so you must read it multiple
* times to insure a safe value is read.
*/
do {
v1 = inl(pmtmr_ioport);
v2 = inl(pmtmr_ioport);
v3 = inl(pmtmr_ioport);
} while ((v1 > v2 && v1 < v3) || (v2 > v3 && v2 < v1)
|| (v3 > v1 && v3 < v2));
/* mask the output to 24 bits */
return v2 & ACPI_PM_MASK;
}
return inl(pmtmr_ioport) & ACPI_PM_MASK;
}
/*
* Some boards have the PMTMR running way too fast. We check
* the PMTMR rate against PIT channel 2 to catch these cases.
*/
static int verify_pmtmr_rate(void)
{
u32 value1, value2;
unsigned long count, delta;
mach_prepare_counter();
value1 = read_pmtmr();
mach_countup(&count);
value2 = read_pmtmr();
delta = (value2 - value1) & ACPI_PM_MASK;
/* Check that the PMTMR delta is within 5% of what we expect */
if (delta < (PMTMR_EXPECTED_RATE * 19) / 20 ||
delta > (PMTMR_EXPECTED_RATE * 21) / 20) {
printk(KERN_INFO "PM-Timer running at invalid rate: %lu%% of normal - aborting.\n", 100UL * delta / PMTMR_EXPECTED_RATE);
return -1;
}
return 0;
}
static int init_pmtmr(char* override)
{
u32 value1, value2;
unsigned int i;
if (override[0] && strncmp(override,"pmtmr",5))
return -ENODEV;
if (!pmtmr_ioport)
return -ENODEV;
/* we use the TSC for delay_pmtmr, so make sure it exists */
if (!cpu_has_tsc)
return -ENODEV;
/* "verify" this timing source */
value1 = read_pmtmr();
for (i = 0; i < 10000; i++) {
value2 = read_pmtmr();
if (value2 == value1)
continue;
if (value2 > value1)
goto pm_good;
if ((value2 < value1) && ((value2) < 0xFFF))
goto pm_good;
printk(KERN_INFO "PM-Timer had inconsistent results: 0x%#x, 0x%#x - aborting.\n", value1, value2);
return -EINVAL;
}
printk(KERN_INFO "PM-Timer had no reasonable result: 0x%#x - aborting.\n", value1);
return -ENODEV;
pm_good:
if (verify_pmtmr_rate() != 0)
return -ENODEV;
init_cpu_khz();
return 0;
}
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);
}
/*
* this gets called during each timer interrupt
* - Called while holding the writer xtime_lock
*/
static void mark_offset_pmtmr(void)
{
u32 lost, delta, last_offset;
static int first_run = 1;
last_offset = offset_tick;
write_seqlock(&monotonic_lock);
offset_tick = read_pmtmr();
/* calculate tick interval */
delta = (offset_tick - last_offset) & ACPI_PM_MASK;
/* convert to usecs */
delta = cyc2us(delta);
/* update the monotonic base value */
monotonic_base += delta * NSEC_PER_USEC;
write_sequnlock(&monotonic_lock);
/* convert to ticks */
delta += offset_delay;
lost = delta / (USEC_PER_SEC / HZ);
offset_delay = delta % (USEC_PER_SEC / HZ);
/* compensate for lost ticks */
if (lost >= 2)
jiffies_64 += lost - 1;
/* 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;
}
}
static int pmtmr_resume(void)
{
write_seqlock(&monotonic_lock);
/* Assume this is the last mark offset time */
offset_tick = read_pmtmr();
write_sequnlock(&monotonic_lock);
return 0;
}
static unsigned long long monotonic_clock_pmtmr(void)
{
u32 last_offset, this_offset;
unsigned long long base, ret;
unsigned seq;
/* atomically read monotonic base & last_offset */
do {
seq = read_seqbegin(&monotonic_lock);
last_offset = offset_tick;
base = monotonic_base;
} while (read_seqretry(&monotonic_lock, seq));
/* Read the pmtmr */
this_offset = read_pmtmr();
/* convert to nanoseconds */
ret = (this_offset - last_offset) & ACPI_PM_MASK;
ret = base + (cyc2us(ret) * NSEC_PER_USEC);
return ret;
}
static void delay_pmtmr(unsigned long loops)
{
unsigned long bclock, now;
rdtscl(bclock);
do
{
rep_nop();
rdtscl(now);
} while ((now-bclock) < loops);
}
/*
* get the offset (in microseconds) from the last call to mark_offset()
* - Called holding a reader xtime_lock
*/
static unsigned long get_offset_pmtmr(void)
{
u32 now, offset, delta = 0;
offset = offset_tick;
now = read_pmtmr();
delta = (now - offset)&ACPI_PM_MASK;
return (unsigned long) offset_delay + cyc2us(delta);
}
/* acpi timer_opts struct */
static struct timer_opts timer_pmtmr = {
.name = "pmtmr",
.mark_offset = mark_offset_pmtmr,
.get_offset = get_offset_pmtmr,
.monotonic_clock = monotonic_clock_pmtmr,
.delay = delay_pmtmr,
.read_timer = read_timer_tsc,
.resume = pmtmr_resume,
};
struct init_timer_opts __initdata timer_pmtmr_init = {
.init = init_pmtmr,
.opts = &timer_pmtmr,
};
#ifdef CONFIG_PCI
/*
* PIIX4 Errata:
*
* The power management timer may return improper results when read.
* Although the timer value settles properly after incrementing,
* while incrementing there is a 3 ns window every 69.8 ns where the
* timer value is indeterminate (a 4.2% chance that the data will be
* incorrect when read). As a result, the ACPI free running count up
* timer specification is violated due to erroneous reads.
*/
static int __init pmtmr_bug_check(void)
{
static struct pci_device_id gray_list[] __initdata = {
/* these chipsets may have bug. */
{ PCI_DEVICE(PCI_VENDOR_ID_INTEL,
PCI_DEVICE_ID_INTEL_82801DB_0) },
{ },
};
struct pci_dev *dev;
int pmtmr_has_bug = 0;
u8 rev;
if (cur_timer != &timer_pmtmr || !pmtmr_need_workaround)
return 0;
dev = pci_get_device(PCI_VENDOR_ID_INTEL,
PCI_DEVICE_ID_INTEL_82371AB_3, NULL);
if (dev) {
pci_read_config_byte(dev, PCI_REVISION_ID, &rev);
/* the bug has been fixed in PIIX4M */
if (rev < 3) {
printk(KERN_WARNING "* Found PM-Timer Bug on this "
"chipset. Due to workarounds for a bug,\n"
"* this time source is slow. Consider trying "
"other time sources (clock=)\n");
pmtmr_has_bug = 1;
}
pci_dev_put(dev);
}
if (pci_dev_present(gray_list)) {
printk(KERN_WARNING "* This chipset may have PM-Timer Bug. Due"
" to workarounds for a bug,\n"
"* this time source is slow. If you are sure your timer"
" does not have\n"
"* this bug, please use \"pmtmr_good\" to disable the "
"workaround\n");
pmtmr_has_bug = 1;
}
if (!pmtmr_has_bug)
pmtmr_need_workaround = 0;
return 0;
}
device_initcall(pmtmr_bug_check);
#endif
static int __init pmtr_good_setup(char *__str)
{
pmtmr_need_workaround = 0;
return 1;
}
__setup("pmtmr_good", pmtr_good_setup);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Dominik Brodowski <linux@brodo.de>");
MODULE_DESCRIPTION("Power Management Timer (PMTMR) as primary timing source for x86");
arch/i386/kernel/timers/timer_tsc.c 已删除 100644 → 0
浏览文件 @ 6f84fa2f
/*
* This code largely moved from arch/i386/kernel/time.c.
* See comments there for proper credits.
*
* 2004-06-25 Jesper Juhl
* moved mark_offset_tsc below cpufreq_delayed_get to avoid gcc 3.4
* failing to inline.
*/
#include <linux/spinlock.h>
#include <linux/init.h>
#include <linux/timex.h>
#include <linux/errno.h>
#include <linux/cpufreq.h>
#include <linux/string.h>
#include <linux/jiffies.h>
#include <asm/timer.h>
#include <asm/io.h>
/* processor.h for distable_tsc flag */
#include <asm/processor.h>
#include "io_ports.h"
#include "mach_timer.h"
#include <asm/hpet.h>
#include <asm/i8253.h>
#ifdef CONFIG_HPET_TIMER
static unsigned long hpet_usec_quotient;
static unsigned long hpet_last;
static struct timer_opts timer_tsc;
#endif
static int use_tsc;
/* Number of usecs that the last interrupt was delayed */
static int delay_at_last_interrupt;
static unsigned long last_tsc_low; /* lsb 32 bits of Time Stamp Counter */
static unsigned long last_tsc_high; /* msb 32 bits of Time Stamp Counter */
static unsigned long long monotonic_base;
static seqlock_t monotonic_lock = SEQLOCK_UNLOCKED;
/* Avoid compensating for lost ticks before TSCs are synched */
static int detect_lost_ticks;
static int __init start_lost_tick_compensation(void)
{
detect_lost_ticks = 1;
return 0;
}
late_initcall(start_lost_tick_compensation);
/* convert from cycles(64bits) => nanoseconds (64bits)
* basic equation:
* ns = cycles / (freq / ns_per_sec)
* ns = cycles * (ns_per_sec / freq)
* ns = cycles * (10^9 / (cpu_khz * 10^3))
* ns = cycles * (10^6 / cpu_khz)
*
* Then we use scaling math (suggested by george@mvista.com) to get:
* ns = cycles * (10^6 * SC / cpu_khz) / SC
* ns = cycles * cyc2ns_scale / SC
*
* And since SC is a constant power of two, we can convert the div
* into a shift.
*
* We can use khz divisor instead of mhz to keep a better percision, since
* cyc2ns_scale is limited to 10^6 * 2^10, which fits in 32 bits.
* (mathieu.desnoyers@polymtl.ca)
*
* -johnstul@us.ibm.com "math is hard, lets go shopping!"
*/
static unsigned long cyc2ns_scale __read_mostly;
#define CYC2NS_SCALE_FACTOR 10 /* 2^10, carefully chosen */
static inline void set_cyc2ns_scale(unsigned long cpu_khz)
{
cyc2ns_scale = (1000000 << CYC2NS_SCALE_FACTOR)/cpu_khz;
}
static inline unsigned long long cycles_2_ns(unsigned long long cyc)
{
return (cyc * cyc2ns_scale) >> CYC2NS_SCALE_FACTOR;
}
static int count2; /* counter for mark_offset_tsc() */
/* Cached *multiplier* to convert TSC counts to microseconds.
* (see the equation below).
* Equal to 2^32 * (1 / (clocks per usec) ).
* Initialized in time_init.
*/
static unsigned long fast_gettimeoffset_quotient;
static unsigned long get_offset_tsc(void)
{
register unsigned long eax, edx;
/* Read the Time Stamp Counter */
rdtsc(eax,edx);
/* .. relative to previous jiffy (32 bits is enough) */
eax -= last_tsc_low; /* tsc_low delta */
/*
* Time offset = (tsc_low delta) * fast_gettimeoffset_quotient
* = (tsc_low delta) * (usecs_per_clock)
* = (tsc_low delta) * (usecs_per_jiffy / clocks_per_jiffy)
*
* Using a mull instead of a divl saves up to 31 clock cycles
* in the critical path.
*/
__asm__("mull %2"
:"=a" (eax), "=d" (edx)
:"rm" (fast_gettimeoffset_quotient),
"0" (eax));
/* our adjusted time offset in microseconds */
return delay_at_last_interrupt + edx;
}
static unsigned long long monotonic_clock_tsc(void)
{
unsigned long long last_offset, this_offset, base;
unsigned seq;
/* atomically read monotonic base & last_offset */
do {
seq = read_seqbegin(&monotonic_lock);
last_offset = ((unsigned long long)last_tsc_high<<32)|last_tsc_low;
base = monotonic_base;
} while (read_seqretry(&monotonic_lock, seq));
/* Read the Time Stamp Counter */
rdtscll(this_offset);
/* return the value in ns */
return base + cycles_2_ns(this_offset - last_offset);
}
static void delay_tsc(unsigned long loops)
{
unsigned long bclock, now;
rdtscl(bclock);
do
{
rep_nop();
rdtscl(now);
} while ((now-bclock) < loops);
}
#ifdef CONFIG_HPET_TIMER
static void mark_offset_tsc_hpet(void)
{
unsigned long long this_offset, last_offset;
unsigned long offset, temp, hpet_current;
write_seqlock(&monotonic_lock);
last_offset = ((unsigned long long)last_tsc_high<<32)|last_tsc_low;
/*
* It is important that these two operations happen almost at
* the same time. We do the RDTSC stuff first, since it's
* faster. To avoid any inconsistencies, we need interrupts
* disabled locally.
*/
/*
* Interrupts are just disabled locally since the timer irq
* has the SA_INTERRUPT flag set. -arca
*/
/* read Pentium cycle counter */
hpet_current = hpet_readl(HPET_COUNTER);
rdtsc(last_tsc_low, last_tsc_high);
/* lost tick compensation */
offset = hpet_readl(HPET_T0_CMP) - hpet_tick;
if (unlikely(((offset - hpet_last) > hpet_tick) && (hpet_last != 0))
&& detect_lost_ticks) {
int lost_ticks = (offset - hpet_last) / hpet_tick;
jiffies_64 += lost_ticks;
}
hpet_last = hpet_current;
/* update the monotonic base value */
this_offset = ((unsigned long long)last_tsc_high<<32)|last_tsc_low;
monotonic_base += cycles_2_ns(this_offset - last_offset);
write_sequnlock(&monotonic_lock);
/* calculate delay_at_last_interrupt */
/*
* Time offset = (hpet delta) * ( usecs per HPET clock )
* = (hpet delta) * ( usecs per tick / HPET clocks per tick)
* = (hpet delta) * ( hpet_usec_quotient ) / (2^32)
* Where,
* hpet_usec_quotient = (2^32 * usecs per tick)/HPET clocks per tick
*/
delay_at_last_interrupt = hpet_current - offset;
ASM_MUL64_REG(temp, delay_at_last_interrupt,
hpet_usec_quotient, delay_at_last_interrupt);
}
#endif
static void mark_offset_tsc(void)
{
unsigned long lost,delay;
unsigned long delta = last_tsc_low;
int count;
int countmp;
static int count1 = 0;
unsigned long long this_offset, last_offset;
static int lost_count = 0;
write_seqlock(&monotonic_lock);
last_offset = ((unsigned long long)last_tsc_high<<32)|last_tsc_low;
/*
* It is important that these two operations happen almost at
* the same time. We do the RDTSC stuff first, since it's
* faster. To avoid any inconsistencies, we need interrupts
* disabled locally.
*/
/*
* Interrupts are just disabled locally since the timer irq
* has the SA_INTERRUPT flag set. -arca
*/
/* read Pentium cycle counter */
rdtsc(last_tsc_low, last_tsc_high);
spin_lock(&i8253_lock);
outb_p(0x00, PIT_MODE); /* latch the count ASAP */
count = inb_p(PIT_CH0); /* read the latched count */
count |= inb(PIT_CH0) << 8;
/*
* VIA686a test code... reset the latch if count > max + 1
* from timer_pit.c - cjb
*/
if (count > LATCH) {
outb_p(0x34, PIT_MODE);
outb_p(LATCH & 0xff, PIT_CH0);
outb(LATCH >> 8, PIT_CH0);
count = LATCH - 1;
}
spin_unlock(&i8253_lock);
if (pit_latch_buggy) {
/* get center value of last 3 time lutch */
if ((count2 >= count && count >= count1)
|| (count1 >= count && count >= count2)) {
count2 = count1; count1 = count;
} else if ((count1 >= count2 && count2 >= count)
|| (count >= count2 && count2 >= count1)) {
countmp = count;count = count2;
count2 = count1;count1 = countmp;
} else {
count2 = count1; count1 = count; count = count1;
}
}
/* lost tick compensation */
delta = last_tsc_low - delta;
{
register unsigned long eax, edx;
eax = delta;
__asm__("mull %2"
:"=a" (eax), "=d" (edx)
:"rm" (fast_gettimeoffset_quotient),
"0" (eax));
delta = edx;
}
delta += delay_at_last_interrupt;
lost = delta/(1000000/HZ);
delay = delta%(1000000/HZ);
if (lost >= 2 && detect_lost_ticks) {
jiffies_64 += lost-1;
/* sanity check to ensure we're not always losing ticks */
if (lost_count++ > 100) {
printk(KERN_WARNING "Losing too many ticks!\n");
printk(KERN_WARNING "TSC cannot be used as a timesource. \n");
printk(KERN_WARNING "Possible reasons for this are:\n");
printk(KERN_WARNING " You're running with Speedstep,\n");
printk(KERN_WARNING " You don't have DMA enabled for your hard disk (see hdparm),\n");
printk(KERN_WARNING " Incorrect TSC synchronization on an SMP system (see dmesg).\n");
printk(KERN_WARNING "Falling back to a sane timesource now.\n");
clock_fallback();
}
} else
lost_count = 0;
/* update the monotonic base value */
this_offset = ((unsigned long long)last_tsc_high<<32)|last_tsc_low;
monotonic_base += cycles_2_ns(this_offset - last_offset);
write_sequnlock(&monotonic_lock);
/* calculate delay_at_last_interrupt */
count = ((LATCH-1) - count) * TICK_SIZE;
delay_at_last_interrupt = (count + LATCH/2) / LATCH;
/* catch corner case where tick rollover occured
* between tsc and pit reads (as noted when
* usec delta is > 90% # of usecs/tick)
*/
if (lost && abs(delay - delay_at_last_interrupt) > (900000/HZ))
jiffies_64++;
}
static int __init init_tsc(char* override)
{
/* check clock override */
if (override[0] && strncmp(override,"tsc",3)) {
#ifdef CONFIG_HPET_TIMER
if (is_hpet_enabled()) {
printk(KERN_ERR "Warning: clock= override failed. Defaulting to tsc\n");
} else
#endif
{
return -ENODEV;
}
}
/*
* If we have APM enabled or the CPU clock speed is variable
* (CPU stops clock on HLT or slows clock to save power)
* then the TSC timestamps may diverge by up to 1 jiffy from
* 'real time' but nothing will break.
* The most frequent case is that the CPU is "woken" from a halt
* state by the timer interrupt itself, so we get 0 error. In the
* rare cases where a driver would "wake" the CPU and request a
* timestamp, the maximum error is < 1 jiffy. But timestamps are
* still perfectly ordered.
* Note that the TSC counter will be reset if APM suspends
* to disk; this won't break the kernel, though, 'cuz we're
* smart. See arch/i386/kernel/apm.c.
*/
/*
* Firstly we have to do a CPU check for chips with
* a potentially buggy TSC. At this point we haven't run
* the ident/bugs checks so we must run this hook as it
* may turn off the TSC flag.
*
* NOTE: this doesn't yet handle SMP 486 machines where only
* some CPU's have a TSC. Thats never worked and nobody has
* moaned if you have the only one in the world - you fix it!
*/
count2 = LATCH; /* initialize counter for mark_offset_tsc() */
if (cpu_has_tsc) {
unsigned long tsc_quotient;
#ifdef CONFIG_HPET_TIMER
if (is_hpet_enabled() && hpet_use_timer) {
unsigned long result, remain;
printk("Using TSC for gettimeofday\n");
tsc_quotient = calibrate_tsc_hpet(NULL);
timer_tsc.mark_offset = &mark_offset_tsc_hpet;
/*
* Math to calculate hpet to usec multiplier
* Look for the comments at get_offset_tsc_hpet()
*/
ASM_DIV64_REG(result, remain, hpet_tick,
0, KERNEL_TICK_USEC);
if (remain > (hpet_tick >> 1))
result++; /* rounding the result */
hpet_usec_quotient = result;
} else
#endif
{
tsc_quotient = calibrate_tsc();
}
if (tsc_quotient) {
fast_gettimeoffset_quotient = tsc_quotient;
use_tsc = 1;
/*
* We could be more selective here I suspect
* and just enable this for the next intel chips ?
*/
/* report CPU clock rate in Hz.
* The formula is (10^6 * 2^32) / (2^32 * 1 / (clocks/us)) =
* clock/second. Our precision is about 100 ppm.
*/
{ unsigned long eax=0, edx=1000;
__asm__("divl %2"
:"=a" (cpu_khz), "=d" (edx)
:"r" (tsc_quotient),
"0" (eax), "1" (edx));
printk("Detected %u.%03u MHz processor.\n",
cpu_khz / 1000, cpu_khz % 1000);
}
set_cyc2ns_scale(cpu_khz);
return 0;
}
}
return -ENODEV;
}
static int tsc_resume(void)
{
write_seqlock(&monotonic_lock);
/* Assume this is the last mark offset time */
rdtsc(last_tsc_low, last_tsc_high);
#ifdef CONFIG_HPET_TIMER
if (is_hpet_enabled() && hpet_use_timer)
hpet_last = hpet_readl(HPET_COUNTER);
#endif
write_sequnlock(&monotonic_lock);
return 0;
}
/************************************************************/
/* tsc timer_opts struct */
static struct timer_opts timer_tsc = {
.name = "tsc",
.mark_offset = mark_offset_tsc,
.get_offset = get_offset_tsc,
.monotonic_clock = monotonic_clock_tsc,
.delay = delay_tsc,
.read_timer = read_timer_tsc,
.resume = tsc_resume,
};
struct init_timer_opts __initdata timer_tsc_init = {
.init = init_tsc,
.opts = &timer_tsc,
};
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