sead3-time.c
2.42 KB
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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 <asm/cpu.h>
#include <asm/setup.h>
#include <asm/time.h>
#include <asm/irq.h>
#include <asm/mips-boards/generic.h>
static int mips_cpu_timer_irq;
static int mips_cpu_perf_irq;
static void mips_timer_dispatch(void)
{
do_IRQ(mips_cpu_timer_irq);
}
static void mips_perf_dispatch(void)
{
do_IRQ(mips_cpu_perf_irq);
}
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 ;
}
void read_persistent_clock(struct timespec *ts)
{
ts->tv_sec = 0;
ts->tv_nsec = 0;
}
static void __init plat_perf_setup(void)
{
if (cp0_perfcount_irq >= 0) {
if (cpu_has_vint)
set_vi_handler(cp0_perfcount_irq, mips_perf_dispatch);
mips_cpu_perf_irq = MIPS_CPU_IRQ_BASE + cp0_perfcount_irq;
}
}
unsigned int get_c0_compare_int(void)
{
if (cpu_has_vint)
set_vi_handler(cp0_compare_irq, mips_timer_dispatch);
mips_cpu_timer_irq = MIPS_CPU_IRQ_BASE + cp0_compare_irq;
return mips_cpu_timer_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);
mips_scroll_message();
plat_perf_setup();
}