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drivers: timer: stm32 lptim minor fix and optimization

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Avoid reading LPTIM counter four times instead of three when second
read doesn't give same value. Use common code, avoid volatile for
local vars.

Signed-off-by: Giancarlo Stasi <giancarlo.stasi.co@gmail.com>
This commit is contained in:
Giancarlo Stasi 2020-06-18 16:34:28 +02:00 • committed by Carles Cufí
commit 259b30016b
1 changed files with 20 additions and 29 deletions
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49
drivers/timer/stm32_lptim_timer.c
View file

@ -166,6 +166,23 @@ int z_clock_driver_init(struct device *device)
return 0;
}
static inline uint32_t z_clock_lptim_getcounter(void)
{
uint32_t lp_time;
uint32_t lp_time_prev_read;
/* It should be noted that to read reliably the content
* of the LPTIM_CNT register, two successive read accesses
* must be performed and compared
*/
lp_time = LL_LPTIM_GetCounter(LPTIM1);
do {
lp_time_prev_read = lp_time;
lp_time = LL_LPTIM_GetCounter(LPTIM1);
} while (lp_time != lp_time_prev_read);
return lp_time;
}
void z_clock_set_timeout(int32_t ticks, bool idle)
{
/* new LPTIM1 AutoReload value to set (aligned on Kernel ticks) */
@ -199,16 +216,7 @@ void z_clock_set_timeout(int32_t ticks, bool idle)
/* read current counter value (cannot exceed 16bit) */
volatile uint32_t lp_time = LL_LPTIM_GetCounter(LPTIM1);
/* It should be noted that to read reliably the content
* of the LPTIM_CNT register, two successive read accesses
* must be performed and compared
*/
while (lp_time != LL_LPTIM_GetCounter(LPTIM1)) {
lp_time = LL_LPTIM_GetCounter(LPTIM1);
}
uint32_t lp_time = z_clock_lptim_getcounter();
uint32_t autoreload = LL_LPTIM_GetAutoReload(LPTIM1);
@ -263,16 +271,7 @@ uint32_t z_clock_elapsed(void)
k_spinlock_key_t key = k_spin_lock(&lock);
volatile uint32_t lp_time = LL_LPTIM_GetCounter(LPTIM1);
/* It should be noted that to read reliably the content
* of the LPTIM_CNT register, two successive read accesses
* must be performed and compared
*/
while (lp_time != LL_LPTIM_GetCounter(LPTIM1)) {
lp_time = LL_LPTIM_GetCounter(LPTIM1);
}
uint32_t lp_time = z_clock_lptim_getcounter();
/* In case of counter roll-over, add this value,
* even if the irq has not yet been handled
@ -298,15 +297,7 @@ uint32_t z_timer_cycle_get_32(void)
k_spinlock_key_t key = k_spin_lock(&lock);
volatile uint32_t lp_time = LL_LPTIM_GetCounter(LPTIM1);
/* It should be noted that to read reliably the content
* of the LPTIM_CNT register, two successive read accesses
* must be performed and compared
*/
while (lp_time != LL_LPTIM_GetCounter(LPTIM1)) {
lp_time = LL_LPTIM_GetCounter(LPTIM1);
}
uint32_t lp_time = z_clock_lptim_getcounter();
/* In case of counter roll-over, add this value,
* even if the irq has not yet been handled