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/*
* (C) Copyright 2008 - 2013 Tensilica Inc.
*
* SPDX-License-Identifier: GPL-2.0+
*/
#include <common.h>
#include <asm/global_data.h>
#include <linux/stringify.h>
DECLARE_GLOBAL_DATA_PTR;
#if XCHAL_HAVE_CCOUNT
static ulong get_ccount(void)
{
ulong ccount;
asm volatile ("rsr %0,"__stringify(CCOUNT) : "=a" (ccount));
return ccount;
}
#else
static ulong fake_ccount;
#define get_ccount() fake_ccount
#endif
static void delay_cycles(unsigned cycles)
{
#if XCHAL_HAVE_CCOUNT
unsigned expiry = get_ccount() + cycles;
while ((signed)(expiry - get_ccount()) > 0)
;
#else
#warning "Without Xtensa timer option, timing will not be accurate."
/*
* Approximate the cycle count by a loop iteration count.
* This is highly dependent on config and optimization.
*/
volatile unsigned i;
for (i = cycles >> 4U; i > 0; --i)
;
fake_ccount += cycles;
#endif
}
/*
* Delay (busy-wait) for a number of microseconds.
*/
void __udelay(unsigned long usec)
{
ulong lo, hi, i;
ulong mhz = CONFIG_SYS_CLK_FREQ / 1000000;
/* Scale to support full 32-bit usec range */
lo = usec & ((1<<22)-1);
hi = usec >> 22UL;
for (i = 0; i < hi; ++i)
delay_cycles(mhz << 22);
delay_cycles(mhz * lo);
}
/*
* Return the elapsed time (ticks) since 'base'.
*/
ulong get_timer(ulong base)
{
/* Don't tie up a timer; use cycle counter if available (or fake it) */
#if XCHAL_HAVE_CCOUNT
register ulong ccount;
__asm__ volatile ("rsr %0, CCOUNT" : "=a"(ccount));
return ccount / (CONFIG_SYS_CLK_FREQ / CONFIG_SYS_HZ) - base;
#else
/*
* Add at least the overhead of this call (in cycles).
* Avoids hanging in case caller doesn't use udelay().
* Note that functions that don't call udelay() (such as
* the "sleep" command) will not get a significant delay
* because there is no time reference.
*/
fake_ccount += 20;
return fake_ccount / (CONFIG_SYS_CLK_FREQ / CONFIG_SYS_HZ) - base;
#endif
}
/*
* This function is derived from ARM/PowerPC code (read timebase as long long).
* On Xtensa it just returns the timer value.
*/
unsigned long long get_ticks(void)
{
return get_timer(0);
}
/*
* This function is derived from ARM/PowerPC code (timebase clock frequency).
* On Xtensa it returns the number of timer ticks per second.
*/
ulong get_tbclk(void)
{
return CONFIG_SYS_HZ;
}
#if XCHAL_HAVE_CCOUNT
unsigned long timer_get_us(void)
{
unsigned long ccount;
__asm__ volatile ("rsr %0, CCOUNT" : "=a"(ccount));
return ccount / (CONFIG_SYS_CLK_FREQ / 1000000);
}
#endif
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