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drivers: entropy: stm32: Add power management constraints

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Add power management constraints to the entropy driver.
This prevents the hardware block to lose it's clock when
going into any stop mode of the cpu, which would cause the
clock error flag to be set while filling the pool.

Signed-off-by: Wouter Cappelle <wouter.cappelle@crodeon.com>
This commit is contained in:
Wouter Cappelle 2022-02-02 09:37:55 +01:00 • committed by Anas Nashif
commit 13faa9aa71
1 changed files with 11 additions and 1 deletions
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12
drivers/entropy/entropy_stm32.c
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@ -18,6 +18,7 @@
#include <sys/util.h>
#include <errno.h>
#include <soc.h>
#include <pm/pm.h>
#include <stm32_ll_bus.h>
#include <stm32_ll_rcc.h>
#include <stm32_ll_rng.h>
@ -243,7 +244,9 @@ static uint16_t rng_pool_get(struct rng_pool *rngp, uint8_t *buf, uint16_t len)
len = dst - buf;
available = available - len;
if (available <= rngp->threshold) {
if ((available <= rngp->threshold)
&& !LL_RNG_IsEnabledIT(entropy_stm32_rng_data.rng)) {
pm_constraint_set(PM_STATE_SUSPEND_TO_IDLE);
LL_RNG_EnableIT(entropy_stm32_rng_data.rng);
}
@ -297,6 +300,7 @@ static void stm32_rng_isr(const void *arg)
byte);
if (ret < 0) {
LL_RNG_DisableIT(entropy_stm32_rng_data.rng);
pm_constraint_release(PM_STATE_SUSPEND_TO_IDLE);
}
k_sem_give(&entropy_stm32_rng_data.sem_sync);
@ -492,6 +496,12 @@ static int entropy_stm32_rng_init(const struct device *dev)
LL_RNG_SetHealthConfig(dev_data->rng, DT_INST_PROP(0, health_test_config));
#endif
/* Prevent the clocks to be stopped during the duration the
* rng pool is being populated. The ISR will release the constraint again
* when the rng pool is filled.
*/
pm_constraint_set(PM_STATE_SUSPEND_TO_IDLE);
LL_RNG_EnableIT(dev_data->rng);
LL_RNG_Enable(dev_data->rng);