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/*
* This file is subject to the terms and conditions of the GNU General Public
* License. See the file "COPYING" in the main directory of this archive
* for more details.
*
* Copyright (C) 2007 by Ralf Baechle
*/
#include <linux/clocksource.h>
#include <linux/init.h>
#include <asm/time.h>
#include <asm/octeon/octeon.h>
#include <asm/octeon/cvmx-ipd-defs.h>
/*
* Set the current core's cvmcount counter to the value of the
* IPD_CLK_COUNT. We do this on all cores as they are brought
* on-line. This allows for a read from a local cpu register to
* access a synchronized counter.
*
*/
void octeon_init_cvmcount(void)
{
unsigned long flags;
unsigned loops = 2;
/* Clobber loops so GCC will not unroll the following while loop. */
asm("" : "+r" (loops));
local_irq_save(flags);
/*
* Loop several times so we are executing from the cache,
* which should give more deterministic timing.
*/
while (loops--)
write_c0_cvmcount(cvmx_read_csr(CVMX_IPD_CLK_COUNT));
local_irq_restore(flags);
}
static cycle_t octeon_cvmcount_read(struct clocksource *cs)
{
return read_c0_cvmcount();
}
static struct clocksource clocksource_mips = {
.name = "OCTEON_CVMCOUNT",
.read = octeon_cvmcount_read,
.mask = CLOCKSOURCE_MASK(64),
.flags = CLOCK_SOURCE_IS_CONTINUOUS,
};
unsigned long long notrace sched_clock(void)
{
/* 64-bit arithmatic can overflow, so use 128-bit. */
#if (__GNUC__ < 4) || ((__GNUC__ == 4) && (__GNUC_MINOR__ <= 3))
u64 t1, t2, t3;
unsigned long long rv;
u64 mult = clocksource_mips.mult;
u64 shift = clocksource_mips.shift;
u64 cnt = read_c0_cvmcount();
asm (
"dmultu\t%[cnt],%[mult]\n\t"
"nor\t%[t1],$0,%[shift]\n\t"
"mfhi\t%[t2]\n\t"
"mflo\t%[t3]\n\t"
"dsll\t%[t2],%[t2],1\n\t"
"dsrlv\t%[rv],%[t3],%[shift]\n\t"
"dsllv\t%[t1],%[t2],%[t1]\n\t"
"or\t%[rv],%[t1],%[rv]\n\t"
: [rv] "=&r" (rv), [t1] "=&r" (t1), [t2] "=&r" (t2), [t3] "=&r" (t3)
: [cnt] "r" (cnt), [mult] "r" (mult), [shift] "r" (shift)
: "hi", "lo");
return rv;
#else
/* GCC > 4.3 do it the easy way. */
unsigned int __attribute__((mode(TI))) t;
t = read_c0_cvmcount();
t = t * clocksource_mips.mult;
return (unsigned long long)(t >> clocksource_mips.shift);
#endif
}
void __init plat_time_init(void)
{
clocksource_mips.rating = 300;
clocksource_set_clock(&clocksource_mips, mips_hpt_frequency);
clocksource_register(&clocksource_mips);
}
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