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Merge #19035

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19035: cpu/nrf5x_common: implement timer_set() r=maribu a=maribu

### Contribution description

The fallback implementation of timer_set() in `drivers/periph_common` is known to fail on short relative sets. This adds a robust implementation.

### Testing procedure

Run `tests/periph_timer_short_relative_set` at least a few dozen times (or use https://github.com/RIOT-OS/RIOT/pull/19030 to have a few dozen repetitions of the test case in a single run of the test application). It should now succeed.

### Issues/PRs references

None

Co-authored-by: Marian Buschsieweke <marian.buschsieweke@ovgu.de>
This commit is contained in:
bors[bot] 2022-12-23 18:20:09 +00:00 committed by GitHub
commit abc66dce73
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2 changed files with 60 additions and 0 deletions
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5
cpu/nrf5x_common/include/periph_cpu_common.h
View File

@ -199,6 +199,11 @@ typedef struct {
uint8_t irqn; /**< IRQ number of the timer device */
} timer_conf_t;
/**
* @brief The nRF5x periph_timer implements timer_set()
*/
#define PERIPH_TIMER_PROVIDES_SET 1
#ifndef DOXYGEN
/**
* @brief Override SPI mode values

55
cpu/nrf5x_common/periph/timer.c
View File

@ -23,6 +23,7 @@
* @}
*/
#include "irq.h"
#include "periph/timer.h"
#define F_TIMER (16000000U) /* the timer is clocked at 16MHz */
@ -100,7 +101,10 @@ int timer_set_absolute(tim_t tim, int chan, unsigned int value)
return -1;
}
unsigned irq_state = irq_disable();
ctx[tim].flags |= (1 << chan);
ctx[tim].is_periodic &= ~(1 << chan);
irq_restore(irq_state);
dev(tim)->CC[chan] = value;
/* clear spurious IRQs */
@ -113,6 +117,55 @@ int timer_set_absolute(tim_t tim, int chan, unsigned int value)
return 0;
}
int timer_set(tim_t tim, int chan, unsigned int timeout)
{
static const uint32_t max_mask[] = {
[TIMER_BITMODE_BITMODE_08Bit] = 0x000000ff,
[TIMER_BITMODE_BITMODE_16Bit] = 0x0000ffff,
[TIMER_BITMODE_BITMODE_24Bit] = 0x00ffffff,
[TIMER_BITMODE_BITMODE_32Bit] = 0xffffffff,
};
/* see if channel is valid */
if (chan >= timer_config[tim].channels) {
return -1;
}
unsigned value = timer_read(tim) + timeout;
unsigned irq_state = irq_disable();
ctx[tim].flags |= (1 << chan);
ctx[tim].is_periodic &= ~(1 << chan);
dev(tim)->CC[chan] = value;
/* clear spurious IRQs */
dev(tim)->EVENTS_COMPARE[chan] = 0;
(void)dev(tim)->EVENTS_COMPARE[chan];
/* enable IRQ */
dev(tim)->INTENSET = (TIMER_INTENSET_COMPARE0_Msk << chan);
unsigned expires = value - timer_read(tim);
expires &= max_mask[timer_config[tim].bitmode];
if (expires > timeout) {
/* timer already expired, check if IRQ flag is set */
if (!dev(tim)->EVENTS_COMPARE[chan]) {
/* timer has expired but IRQ flag is not set. The only way to not
* wait *a full period* is now to set a new target to the next tick.
* (Setting it to the current timer value will not trigger the IRQ
* flag.) We briefly stop the timer to avoid a race, losing one
* timer tick in accuracy. But that is better than a timer firing
* a whole period too late */
dev(tim)->TASKS_STOP = 1;
dev(tim)->CC[chan] = timer_read(tim) + 1;
dev(tim)->TASKS_START = 1;
}
}
irq_restore(irq_state);
return 0;
}
int timer_set_periodic(tim_t tim, int chan, unsigned int value, uint8_t flags)
{
/* see if channel is valid */
@ -123,8 +176,10 @@ int timer_set_periodic(tim_t tim, int chan, unsigned int value, uint8_t flags)
/* stop timer to avoid race condition */
dev(tim)->TASKS_STOP = 1;
unsigned irq_state = irq_disable();
ctx[tim].flags |= (1 << chan);
ctx[tim].is_periodic |= (1 << chan);
irq_restore(irq_state);
dev(tim)->CC[chan] = value;
if (flags & TIM_FLAG_RESET_ON_MATCH) {
dev(tim)->SHORTS |= (1 << chan);