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bsps/arm: Remove DWT based clock.

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It seems that the DWT CYCCNT does not advance when the CPU waits on a
WFI instruction.

That leads to the effect that for example on the atsamv BSP a sleep(1)
needs something in the range of a few minutes (depending on the
configured systick). A debugger might disables some deep sleep modes so
that the problem only appears if the application is executed without a
debugger.
This commit is contained in:
Christian Mauderer
2017-10-17 11:46:15 +02:00
committed by Sebastian Huber
parent 205d8d71a6
commit 248f8679a7
1 changed files with 7 additions and 30 deletions
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37
c/src/lib/libbsp/arm/shared/armv7m/clock/armv7m-clock-config.c
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@@ -88,18 +88,6 @@ static void _ARMV7M_TC_systick_tick(void)
);
}
static uint32_t _ARMV7M_TC_dwt_get_timecount(struct timecounter *tc)
{
volatile ARMV7M_DWT *dwt = _ARMV7M_DWT;
return dwt->cyccnt;
}
static void _ARMV7M_TC_dwt_tick(void)
{
rtems_timecounter_tick();
}
static void _ARMV7M_TC_tick(void)
{
(*_ARMV7M_TC.tick)();
@@ -131,7 +119,6 @@ static void _ARMV7M_Systick_initialize(void)
#endif
uint64_t us_per_tick = rtems_configuration_get_microseconds_per_tick();
uint64_t interval = (freq * us_per_tick) / 1000000ULL;
bool cyccnt_enabled;
systick->rvr = (uint32_t) interval;
systick->cvr = 0;
@@ -139,23 +126,13 @@ static void _ARMV7M_Systick_initialize(void)
| ARMV7M_SYSTICK_CSR_TICKINT
| ARMV7M_SYSTICK_CSR_CLKSOURCE;
cyccnt_enabled = _ARMV7M_DWT_Enable_CYCCNT();
if (cyccnt_enabled) {
_ARMV7M_TC.base.tc.tc_get_timecount = _ARMV7M_TC_dwt_get_timecount;
_ARMV7M_TC.base.tc.tc_counter_mask = 0xffffffff;
_ARMV7M_TC.base.tc.tc_frequency = freq;
_ARMV7M_TC.base.tc.tc_quality = RTEMS_TIMECOUNTER_QUALITY_CLOCK_DRIVER;
_ARMV7M_TC.tick = _ARMV7M_TC_dwt_tick;
rtems_timecounter_install(&_ARMV7M_TC.base.tc);
} else {
_ARMV7M_TC.tick = _ARMV7M_TC_systick_tick;
rtems_timecounter_simple_install(
&_ARMV7M_TC.base,
freq,
interval,
_ARMV7M_TC_systick_get_timecount
);
}
_ARMV7M_TC.tick = _ARMV7M_TC_systick_tick;
rtems_timecounter_simple_install(
&_ARMV7M_TC.base,
freq,
interval,
_ARMV7M_TC_systick_get_timecount
);
}
static void _ARMV7M_Systick_cleanup(void)