Contributors: 19
| Author |
Tokens |
Token Proportion |
Commits |
Commit Proportion |
| Huang Rui |
110 |
25.23% |
1 |
3.23% |
| John Stultz |
97 |
22.25% |
2 |
6.45% |
| Linus Torvalds (pre-git) |
60 |
13.76% |
4 |
12.90% |
| Steven Rostedt |
55 |
12.61% |
1 |
3.23% |
| Glauber de Oliveira Costa |
18 |
4.13% |
2 |
6.45% |
| Alan Cox |
17 |
3.90% |
1 |
3.23% |
| Andrew Lutomirski |
15 |
3.44% |
5 |
16.13% |
| Jiri Slaby |
15 |
3.44% |
1 |
3.23% |
| Andrew Morton |
12 |
2.75% |
2 |
6.45% |
| Janakarajan Natarajan |
8 |
1.83% |
1 |
3.23% |
| Dominik Brodowski |
7 |
1.61% |
3 |
9.68% |
| Alexey Dobriyan |
7 |
1.61% |
1 |
3.23% |
| Thomas Gleixner |
5 |
1.15% |
1 |
3.23% |
| Jiri Hladky |
3 |
0.69% |
1 |
3.23% |
| Linus Torvalds |
3 |
0.69% |
1 |
3.23% |
| Paul Gortmaker |
1 |
0.23% |
1 |
3.23% |
| Andi Kleen |
1 |
0.23% |
1 |
3.23% |
| Greg Kroah-Hartman |
1 |
0.23% |
1 |
3.23% |
| Borislav Petkov |
1 |
0.23% |
1 |
3.23% |
| Total |
436 |
|
31 |
|
// SPDX-License-Identifier: GPL-2.0
/*
* Precise Delay Loops for i386
*
* Copyright (C) 1993 Linus Torvalds
* Copyright (C) 1997 Martin Mares <mj@atrey.karlin.mff.cuni.cz>
* Copyright (C) 2008 Jiri Hladky <hladky _dot_ jiri _at_ gmail _dot_ com>
*
* The __delay function must _NOT_ be inlined as its execution time
* depends wildly on alignment on many x86 processors. The additional
* jump magic is needed to get the timing stable on all the CPU's
* we have to worry about.
*/
#include <linux/export.h>
#include <linux/sched.h>
#include <linux/timex.h>
#include <linux/preempt.h>
#include <linux/delay.h>
#include <asm/processor.h>
#include <asm/delay.h>
#include <asm/timer.h>
#include <asm/mwait.h>
#ifdef CONFIG_SMP
# include <asm/smp.h>
#endif
/* simple loop based delay: */
static void delay_loop(unsigned long loops)
{
asm volatile(
" test %0,%0 \n"
" jz 3f \n"
" jmp 1f \n"
".align 16 \n"
"1: jmp 2f \n"
".align 16 \n"
"2: dec %0 \n"
" jnz 2b \n"
"3: dec %0 \n"
: /* we don't need output */
:"a" (loops)
);
}
/* TSC based delay: */
static void delay_tsc(unsigned long __loops)
{
u64 bclock, now, loops = __loops;
int cpu;
preempt_disable();
cpu = smp_processor_id();
bclock = rdtsc_ordered();
for (;;) {
now = rdtsc_ordered();
if ((now - bclock) >= loops)
break;
/* Allow RT tasks to run */
preempt_enable();
rep_nop();
preempt_disable();
/*
* It is possible that we moved to another CPU, and
* since TSC's are per-cpu we need to calculate
* that. The delay must guarantee that we wait "at
* least" the amount of time. Being moved to another
* CPU could make the wait longer but we just need to
* make sure we waited long enough. Rebalance the
* counter for this CPU.
*/
if (unlikely(cpu != smp_processor_id())) {
loops -= (now - bclock);
cpu = smp_processor_id();
bclock = rdtsc_ordered();
}
}
preempt_enable();
}
/*
* On some AMD platforms, MWAITX has a configurable 32-bit timer, that
* counts with TSC frequency. The input value is the loop of the
* counter, it will exit when the timer expires.
*/
static void delay_mwaitx(unsigned long __loops)
{
u64 start, end, delay, loops = __loops;
/*
* Timer value of 0 causes MWAITX to wait indefinitely, unless there
* is a store on the memory monitored by MONITORX.
*/
if (loops == 0)
return;
start = rdtsc_ordered();
for (;;) {
delay = min_t(u64, MWAITX_MAX_LOOPS, loops);
/*
* Use cpu_tss_rw as a cacheline-aligned, seldomly
* accessed per-cpu variable as the monitor target.
*/
__monitorx(raw_cpu_ptr(&cpu_tss_rw), 0, 0);
/*
* AMD, like Intel, supports the EAX hint and EAX=0xf
* means, do not enter any deep C-state and we use it
* here in delay() to minimize wakeup latency.
*/
__mwaitx(MWAITX_DISABLE_CSTATES, delay, MWAITX_ECX_TIMER_ENABLE);
end = rdtsc_ordered();
if (loops <= end - start)
break;
loops -= end - start;
start = end;
}
}
/*
* Since we calibrate only once at boot, this
* function should be set once at boot and not changed
*/
static void (*delay_fn)(unsigned long) = delay_loop;
void use_tsc_delay(void)
{
if (delay_fn == delay_loop)
delay_fn = delay_tsc;
}
void use_mwaitx_delay(void)
{
delay_fn = delay_mwaitx;
}
int read_current_timer(unsigned long *timer_val)
{
if (delay_fn == delay_tsc) {
*timer_val = rdtsc();
return 0;
}
return -1;
}
void __delay(unsigned long loops)
{
delay_fn(loops);
}
EXPORT_SYMBOL(__delay);
noinline void __const_udelay(unsigned long xloops)
{
unsigned long lpj = this_cpu_read(cpu_info.loops_per_jiffy) ? : loops_per_jiffy;
int d0;
xloops *= 4;
asm("mull %%edx"
:"=d" (xloops), "=&a" (d0)
:"1" (xloops), "0" (lpj * (HZ / 4)));
__delay(++xloops);
}
EXPORT_SYMBOL(__const_udelay);
void __udelay(unsigned long usecs)
{
__const_udelay(usecs * 0x000010c7); /* 2**32 / 1000000 (rounded up) */
}
EXPORT_SYMBOL(__udelay);
void __ndelay(unsigned long nsecs)
{
__const_udelay(nsecs * 0x00005); /* 2**32 / 1000000000 (rounded up) */
}
EXPORT_SYMBOL(__ndelay);