delay.c
1.04 KB
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/*
* Precise Delay Loops for SuperH
*
* Copyright (C) 1999 Niibe Yutaka & Kaz Kojima
*/
#include <linux/sched.h>
#include <linux/delay.h>
void __delay(unsigned long loops)
{
__asm__ __volatile__(
/*
* ST40-300 appears to have an issue with this code,
* normally taking two cycles each loop, as with all
* other SH variants. If however the branch and the
* delay slot straddle an 8 byte boundary, this increases
* to 3 cycles.
* This align directive ensures this doesn't occur.
*/
".balign 8\n\t"
"tst %0, %0\n\t"
"1:\t"
"bf/s 1b\n\t"
" dt %0"
: "=r" (loops)
: "0" (loops)
: "t");
}
inline void __const_udelay(unsigned long xloops)
{
xloops *= 4;
__asm__("dmulu.l %0, %2\n\t"
"sts mach, %0"
: "=r" (xloops)
: "0" (xloops),
"r" (cpu_data[raw_smp_processor_id()].loops_per_jiffy * (HZ/4))
: "macl", "mach");
__delay(++xloops);
}
void __udelay(unsigned long usecs)
{
__const_udelay(usecs * 0x000010c6); /* 2**32 / 1000000 */
}
void __ndelay(unsigned long nsecs)
{
__const_udelay(nsecs * 0x00000005);
}