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soc: arm: nordic_nrf: nrf52: Add workaround for anomaly 132

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Added delay before starting low frequency clock for the first time to
ensure that anomaly conditions are not met. Delay is configurable and
might be disabled.

Signed-off-by: Krzysztof Chruscinski <krzysztof.chruscinski@nordicsemi.no>
This commit is contained in:
Krzysztof Chruscinski 2020-01-28 08:05:50 +01:00 • committed by Ioannis Glaropoulos
commit 510102dd71
5 changed files with 48 additions and 0 deletions
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18
drivers/clock_control/nrf_power_clock.c
View file

@ -228,6 +228,18 @@ static struct clock_control_async_data *list_get(sys_slist_t *list)
return async_data;
}
static inline void anomaly_132_workaround(void)
{
#if (CONFIG_NRF52_ANOMALY_132_DELAY_US - 0)
static bool once;
if (!once) {
k_busy_wait(CONFIG_NRF52_ANOMALY_132_DELAY_US);
once = true;
}
#endif
}
static int clock_async_start(struct device *dev,
clock_control_subsys_t subsys,
struct clock_control_async_data *data)
@ -280,6 +292,12 @@ static int clock_async_start(struct device *dev,
config->start_handler(dev) : true;
if (do_start) {
DBG(dev, subsys, "Triggering start task");
if (IS_ENABLED(CONFIG_NRF52_ANOMALY_132_WORKAROUND) &&
(subsys == CLOCK_CONTROL_NRF_SUBSYS_LF)) {
anomaly_132_workaround();
}
nrf_clock_task_trigger(NRF_CLOCK,
config->start_tsk);
} else {

4
soc/arm/nordic_nrf/nrf52/Kconfig.defconfig.nrf52832_CIAA
View file

@ -11,4 +11,8 @@ config SOC
config NUM_IRQS
default 39
config NRF52_ANOMALY_132_WORKAROUND
bool
default y
endif # SOC_NRF52832_CIAA

4
soc/arm/nordic_nrf/nrf52/Kconfig.defconfig.nrf52832_QFAA
View file

@ -11,4 +11,8 @@ config SOC
config NUM_IRQS
default 39
config NRF52_ANOMALY_132_WORKAROUND
bool
default y
endif # SOC_NRF52832_QFAA

4
soc/arm/nordic_nrf/nrf52/Kconfig.defconfig.nrf52832_QFAB
View file

@ -11,4 +11,8 @@ config SOC
config NUM_IRQS
default 39
config NRF52_ANOMALY_132_WORKAROUND
bool
default y
endif # SOC_NRF52832_QFAB

18
soc/arm/nordic_nrf/nrf52/Kconfig.soc
View file

@ -361,3 +361,21 @@ config NRF_ENABLE_ICACHE
bool "Enable the instruction cache (I-Cache)"
depends on SOC_NRF52832 || SOC_NRF52833 || SOC_NRF52840
default y
config NRF52_ANOMALY_132_DELAY_US
int "Anomaly 132 workaround delay (microseconds)"
default 330
range 0 330
depends on NRF52_ANOMALY_132_WORKAROUND
help
Due to Anomaly 132 LF RC source may not start if restarted in certain
window after stopping (230 us to 330 us). Software reset also stops the
clock so if clock is initiated in certain window, the clock may also fail
to start at reboot. A delay is added before starting LF clock to ensure
that anomaly conditions are not met. Delay should be long enough to ensure
that clock is started later than 330 us after reset. If crystal oscillator
(XO) is used then low frequency clock initially starts with RC and then
seamlessly switches to XO which has much longer startup time thus,
depending on application, workaround may also need to be applied.
Additional drivers initialization increases initialization time and delay
may be shortened. Workaround is disabled by setting delay to 0.