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rtc: Add settimeofday() #795

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38 changes: 38 additions & 0 deletions teensy3/pins_teensy.c
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Original file line number Diff line number Diff line change
Expand Up @@ -404,6 +404,38 @@ int _gettimeofday(struct timeval *tv, void *ignore)
}
}

__attribute__((weak))
int settimeofday(const struct timeval *const tv,
const struct timezone *const tz __attribute__((unused))) {
// Notes:
// * The type of tv_usec is suseconds_t, range is [-1, 1000000]
// * There are 32768 ticks per 1,000,000 microseconds; that's where 512/15625
// comes from, it's 32768/1000000 in lowest terms
// Refs:
// * https://pubs.opengroup.org/onlinepubs/007904975/basedefs/sys/time.h.html
// * https://pubs.opengroup.org/onlinepubs/007904975/basedefs/sys/types.h.html
uint32_t sec = (uint32_t)tv->tv_sec;
uint32_t usec = (uint32_t)tv->tv_usec;
if (usec == 1000000) {
sec++;
usec = 0;
} else if (usec == UINT32_MAX) {
sec--;
usec = 999999;
}
const uint32_t lo = ((usec << 9) / 15625) & 0x7fff;

// Disable time counter
RTC_SR = 0;

RTC_TPR = lo;
RTC_TSR = sec;

// Enable time counter
RTC_SR = RTC_SR_TCE;
return 0;
}

#else

unsigned long rtc_get(void) { return 0; }
Expand All @@ -413,6 +445,12 @@ void rtc_compensate(int adjust) { }
__attribute__((weak))
int _gettimeofday(struct timeval *tv, void *ignore) { return -1; }

__attribute__((weak))
int settimeofday(const struct timeval *const tv __attribute__((unused)),
const struct timezone *const tz __attribute__((unused))) {
return -1;
}

#endif


Expand Down
52 changes: 51 additions & 1 deletion teensy4/rtc.c
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Original file line number Diff line number Diff line change
Expand Up @@ -30,7 +30,7 @@

#include "imxrt.h"
#include "debug/printf.h"
#include <sys/time.h> // for struct timeval
#include <sys/time.h> // for struct timeval and struct timezone

unsigned long rtc_get(void)
{
Expand Down Expand Up @@ -88,3 +88,53 @@ int _gettimeofday(struct timeval *tv, void *ignore __attribute__((unused)))
lo1 = lo2;
}
}

__attribute__((weak))
int settimeofday(const struct timeval *const tv,
const struct timezone *const tz __attribute__((unused))) {
// Notes:
// * The type of tv_usec is suseconds_t, range is [-1, 1000000]
// * There are 32768 ticks per 1,000,000 microseconds; that's where 512/15625
// comes from, it's 32768/1000000 in lowest terms
// Refs:
// * https://pubs.opengroup.org/onlinepubs/007904975/basedefs/sys/time.h.html
// * https://pubs.opengroup.org/onlinepubs/007904975/basedefs/sys/types.h.html
uint32_t sec = (uint32_t)tv->tv_sec;
uint32_t usec = (uint32_t)tv->tv_usec;
if (usec == 1000000) {
sec++;
usec = 0;
} else if (usec == UINT32_MAX) {
sec--;
usec = 999999;
}
const uint32_t hi = (sec >> 17) & 0x7fff;
const uint32_t lo = (sec << 15) | (((usec << 9) / 15625) & 0x7fff);

// Stop the RTC
SNVS_HPCR &= ~(SNVS_HPCR_RTC_EN | SNVS_HPCR_HP_TS);
while (SNVS_HPCR & SNVS_HPCR_RTC_EN) {
// Wait
}

// Stop the SRTC
SNVS_LPCR &= ~SNVS_LPCR_SRTC_ENV;
while (SNVS_LPCR & SNVS_LPCR_SRTC_ENV) {
// Wait
}

// Set the SRTC
SNVS_LPSRTCLR = lo;
SNVS_LPSRTCMR = hi;

// Start the SRTC
SNVS_LPCR |= SNVS_LPCR_SRTC_ENV;
while (!(SNVS_LPCR & SNVS_LPCR_SRTC_ENV)) {
// Wait
}

// Start the RTC and sync it to the SRTC
SNVS_HPCR |= SNVS_HPCR_RTC_EN | SNVS_HPCR_HP_TS;

return 0;
}