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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) 2012 MIPS Technologies, Inc. All rights reserved.
*/
#include <linux/init.h>
#include <linux/irqchip/mips-gic.h>
#include <asm/cpu.h>
#include <asm/setup.h>
#include <asm/time.h>
#include <asm/irq.h>
#include <asm/mips-boards/generic.h>
static void __iomem *status_reg = (void __iomem *)0xbf000410;
/*
* Estimate CPU frequency. Sets mips_hpt_frequency as a side-effect.
*/
static unsigned int __init estimate_cpu_frequency(void)
{
unsigned int prid = read_c0_prid() & (PRID_COMP_MASK | PRID_IMP_MASK);
unsigned int tick = 0;
unsigned int freq;
unsigned int orig;
unsigned long flags;
local_irq_save(flags);
orig = readl(status_reg) & 0x2; /* get original sample */
/* wait for transition */
while ((readl(status_reg) & 0x2) == orig)
;
orig = orig ^ 0x2; /* flip the bit */
write_c0_count(0);
/* wait 1 second (the sampling clock transitions every 10ms) */
while (tick < 100) {
/* wait for transition */
while ((readl(status_reg) & 0x2) == orig)
;
orig = orig ^ 0x2; /* flip the bit */
tick++;
}
freq = read_c0_count();
local_irq_restore(flags);
mips_hpt_frequency = freq;
/* Adjust for processor */
if ((prid != (PRID_COMP_MIPS | PRID_IMP_20KC)) &&
(prid != (PRID_COMP_MIPS | PRID_IMP_25KF)))
freq *= 2;
freq += 5000; /* rounding */
freq -= freq%10000;
return freq ;
}
int get_c0_perfcount_int(void)
{
if (gic_present)
return gic_get_c0_perfcount_int();
if (cp0_perfcount_irq >= 0)
return MIPS_CPU_IRQ_BASE + cp0_perfcount_irq;
return -1;
}
EXPORT_SYMBOL_GPL(get_c0_perfcount_int);
unsigned int get_c0_compare_int(void)
{
if (gic_present)
return gic_get_c0_compare_int();
return MIPS_CPU_IRQ_BASE + cp0_compare_irq;
}
void __init plat_time_init(void)
{
unsigned int est_freq;
est_freq = estimate_cpu_frequency();
pr_debug("CPU frequency %d.%02d MHz\n", (est_freq / 1000000),
(est_freq % 1000000) * 100 / 1000000);
}
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